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Brian Greene: String Theory, Faster Than Light, and Death
January 16, 2023
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I've opened up about certain experiences that at the time were absolutely terrifying. Anything that takes your mind into a different place that ultimately you learn something from,
fits within the genre of exploration
Today we talk about consciousness, time travel, string theory, quantum gravity, and wormholes. Brian Green is a theoretical physicist, a mathematician, and a string theorist, who is best known for his work on mirror symmetry and flop transitions. Brian's also a professor at Columbia University, as well as the chairman of the World Science Festival, and the author of several popular books on physics, including The Elegant Universe.
This was a purposefully desultory interview which brought us both to uncomfortable ground comfortably. You'll see what I mean. My name is Kurt Jaimungal. I have a background in mathematical physics. This podcast is called Theories of Everything. It's dedicated to the exploration of theories of everything from a theoretical physics perspective, but as well as exploring the role consciousness has to the fundamental laws of nature.
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Professor Brian Green, it's an honor to speak with you. I've been researching you since I was young and also as I've gotten older, it's an honor. Thank you for coming on. Thank you. Thank you so much. What have you been working on in the past year and what do you hope to accomplish in the next year and this year? Well, I've been working on some strange things of late, which I'm almost afraid to talk about, but since they've been published, I guess I shouldn't at all hold back. But it sounds a little kooky.
It sounds like the kind of things that I received in emails and crank letters for the past 30 years. It has to do with questioning whether the speed of light really is the limit for signal transmission. And we all know that as anyone who's taken basic physics, that is special relativity, that it's an absolutely well established fact that locally,
The speed of light is the limit for signal transmission, obviously going back to Einstein and a gazillion experiments since. But there are some unusual contexts that theories like string theory suggest. And those contexts suggest that the overall shape of space might be non-trivial in the sense that it might not just sort of go on forever. Space might curve back on itself and
You can ask yourself, what if the universe is in the shape of a loop, or at least are dimensions that are looped? That is, you go out in one direction, you go far enough, you'll come back to your starting point. And so we began to study signal transmission in universes where the signal could go all the way around the universe and route to its destination. And we found in certain circumstances that I'd be happy to elaborate that you could have signals
going in that unusual trajectory that would get to their destination faster than the signal that would seemingly be the quicker one moving right through the space time without traversing these closed curves. And so we found that there are signals that can go from here to there faster than the speed of light. This is related to the topology of the universe and not the variable speed of light? Yeah, this is not a variable speed of light.
type of contribution as you know as you're making reference to there's been a whole industry that various physicists pursued over the course of many years wondering about whether the speed of light might vary through time a temporal dependence to the speed of light very interesting idea i really don't know that there's much evidence for it nor is there much evidence for what i'm talking about either so this is like throwing stones in a glass house but be that as it may
You're right. It all has to do with the topology of space. And if that topology is non-trivial, if there are non-contractable loops in that space, then that allows for qualitatively different trajectories for signals. And when you take those into account, you find that the signals can have a net speed that's faster than the speed of light. And moreover, it starts to sound a little bit kooky, but
When you take special relativity, you learn that if signal can go faster than the speed of light, then there are observers according to whom that signal may arrive at its destination prior to the time at which it was emitted. And indeed, we find examples of that. In other words, we find examples where you can send a signal into the past.
And again, I hesitate saying this, but you asked me the question, what I've been working on lately, so I feel I need to answer fully and truthfully. I hesitate to say this because this has sort of been the playground of kind of
A closed timeline curve doesn't go against general relativity. Gödel had a solution
Are you suggesting some amendment to general relativity or are you just saying the actual structure of space-time or the shape of it is different so you're not proposing new laws? No laws. The whole notion of closed timelike curves is a tricky one. That's one where there's a full trajectory that gets back to its starting point prior to when it departed.
exactly find those kind of structures in these theories. So if I send a signal out into space and send it somehow into the past, and then someone in the past gets that signal and fires back toward me, the return signal will always get to me in at least no time. In other words, it won't be that I get the signal prior to the moment when I emitted it. So
This would allow for interesting things such as, you know, we've always worried. Well, worried is probably too strong a word. We've always noted that if we discover intelligent life out there in the cosmos and it's very far away, how are we going to have a conversation, right? We send out a signal. Hey, how you guys doing? And what do we do? We wait like a hundred thousand years or a million years for the return signal. And by that point, we've forgotten that we were in a conversation at all.
But in the theories that I'm describing now with these universes, with these non-trivial topologies, you can send a signal out into space and the person can get it and respond and you will receive it in virtually no time, in as little time as one can imagine. And so you can have a real time conversation with someone who's in an arbitrary distance. So I think that's pretty startling and mind boggling and kind of wonderful.
And who knows if any of these ideas happen to be true, it would allow for conversations that in the more usual setting would just be impossible. But no, it's no amendment to general relativity. It's no change at all to the fundamental laws. That's the kind of fun thing about this approach. You know, if you come along and say, well, let's now bend the laws of physics as we knew it in the past, change it in some way. Sure, obviously, you're going to get some new effects, but then it all
depends on, the utility of it depends on, was that amendment, was that change at all reasonable? So we're not changing the laws of physics at all, we're just considering shapes of space that are very natural in certain unified theories like string theory, you know, Kaluza-Klein type theories that people studied in the past, and just examining conventional physics in a new setting.
As opposed to new physics in either conventional or new setting. Is any of this related to wormholes or is this separate? It is definitely separate from wormholes in the conventional way that people think about wormholes, but there is a deep association in the following sense. If you
are looking at a signal that's traversing say you know a circular dimension of space. One of the most profitable ways scientifically of studying that is to imagine cutting that circle and opening it up into a line say an infinite line and then just having global identifications.
point zero identified with two pi r, identified with four pi i, with six pi r and so forth. And in that way you effectively have a circle because of those identifications but you've unraveled it into a more conventional shape, a line. And then when a signal goes from zero say to two pi r, what's really in some sense happening is the signal is then in essence jumping through a wormhole and going back to its starting point.
And so you can reframe everything that I'm talking about using the language of wormholes, but wormholes are not as essential to the story as it might be in certain other applications where you start to worry about things like, well, is the wormhole traversable? Will it stay open long enough for someone to actually go through or for a signal to go through? In this case, a wormhole is really more of a technique, a mathematical technique for analyzing
the situation as opposed to being fundamental to the whole idea. So this year, your plans are what? To work on this theory some more or? Yeah, we're going to definitely pursue, you know, look. And what is this called, by the way? Sorry, is there a name for this? Or a paper that people can look up? Yeah, we've written a couple of papers on it. The most recent one has the title Back to the Future, which
The editors at Physical Review D initially sent the paper back and said we like the paper but you got to change the title because it's like we just don't have titles like that and I have to say I kind of took a little bit offence is too strong a word but you know we wrote back to them and said sure there's a cultural reference it's kind of fun but it's not just a cultural reference for a cultural references sake we truly are talking about
a signal that can travel from us back to the past and then into the future because as I said before the return signal always gets to us in a non-negative amount of time so it's it's back to the future it's like a perfect description of what we're talking about and to their credit
the editors at Physical Review D finally said, yeah, okay, you're right, it works. So the paper was accepted with that somewhat perhaps loose sounding title, but one that really does have a descriptive approach to what we're talking about that's spot on. And so yeah, if people want to see the technical details, that would be a paper to look at.
And you have an event coming up at least here in Toronto on January 26th, if I'm not mistaken. So that's about a week from now when this is being published, when you're seeing this. Can you tell myself a little bit about that in the audience as well? Yeah, absolutely. So it's a talk at Roy Thompson Hall. I've never been there before, but at least the pictures look like it's a quite beautiful venue. And it's a journey that I'm going to take the audience on from
the beginning of time up to the present and out toward the farthest that science can take us toward the end toward eternity. And my point in taking the audience on this journey will be partly to illuminate some of the key scientific ideas that guide the cosmological unfolding on the largest of scales and the largest of time scales.
But I also want to give people a sense of what science says about how we fit in to this cosmic order from this broadest, this largest perspective. And so we will be covering the formation of stars and galaxies, a little discussion about how entropy and life interplay and play off of one another and then
Once we get to the present, we'll turn our attention toward the future and see how it all comes crashing down when you look at sufficiently large time scales as entropy gains the upper hand. And I'll conclude the evening with some remarks on how one might interpret this large scale understanding of the cosmos in more human terms.
and how it is that perhaps this perspective can shed light on the age-old questions of meaning and purpose, which occupy all of us in one way or another. So how does it shed light on those, on meaning and purpose? Well, objectively. Well, you should come to the evening, but I'm more than happy to discuss it now in broad strokes.
Look, you said objectively and I would say I don't know that objectively there is an answer. I think it is ultimately the subject of search that each human being is ultimately on to try to make sense of their life, make sense of their existence. But what this perspective does for me, and I found that it resonates with many people, it shows us how unbelievably astoundingly unlikely our own existence is.
against the spectrum of possible combinations of base pairs of DNA, against the spectrum of possible molecular configurations, against the spectrum of possible outcome of quantum processes that stretch from the beginning until today, that each of them could have turned out one way versus the way they did, yielding a universe in which we wouldn't be here, against these astounding odds we're here.
And to me, that's the beginning of the most fruitful, compelling and satisfying approach to finding some sense of purpose or meaning. Because rather than looking out to the universe, which we see in many philosophies and frankly, many religions, looking out to the cosmos to bestow upon us some ultimate answer, some ultimate meaning, some ultimate purpose,
This understanding of the cosmological timeline and the astounding unlikeliness of our own existence turns the spotlight inward. It turns the spotlight to a recognition of how astounding it is not only that we exist, but we have the powers that our particulate arrangement endows us with. Look what we can do. We can have this conversation.
We can
To me, that is where a deep kind of gratitude emerges. And that gratitude is for the mere existence of human beings. And it's not dependent upon whether we're going to have some lasting legacy. It rather is just focused on the fact that we're here at all and that we can do the things that we can do. And with that comes an appreciation, which
For me is deeply compelling and satisfying, regardless of my understanding of how evanescent it all is. Do you fear death? I do. And I think that the fear of death is one of the major driving forces of the human species, both as a species as a whole and as individuals. And this is not an original thought.
When I was, I guess, way back in college, I encountered a book called The Denial of Death by Ernest Becker, who himself was channeling and developing ideas of Otto Ronck, one of the great early psychologists who was in the Freudian school to begin with, and then really plowed his own path. And this idea that we humans are
A rare life form that not only can we imagine the future, as I mentioned before, but we recognize that if we look far enough into that future, we're not there. We recognize that we are mortal. And that recognition of mortality fights against the urge for influence, legacy, a lasting part of us
We urge that we don't get washed away by the relentless winds of time, and yet that is not the way the universe is constructed. And so the fear of everything we love, everything we care about, everything we develop, everything that we worry about and spend energy and time on, that it all goes away,
To me is one of the deep insights and the deep motivators for how we humans behave. Have you ever inhabited a dark state of mind for a prolonged period of time? So, for instance, contemplation of suicide or ideation on the supposed objective meaninglessness of the world and that you have to find it subjectively, but maybe it was fringed to your sanity? Yeah, well, I would say that I've never gotten, thankfully,
to the place of sort of suicidal ideation and again you know anybody who has uh you know seek out help and guidance because there there are ways to get to a better place but i have certainly inhabited dark places and some of it has come from the things that we're talking about when you think about the cosmos and the laws of physics and our little tiny planet earth just
floating in this vast, perhaps infinitely vast darkness, there is a way that if you take that in emotionally as opposed to just purely intellectually, it can take you to a place of darkness and fear, foreboding. And I have explored that.
So how have you gotten out of that? Well, one solution may be to separate the intellect and the emotion and just explore the vastness of the cosmos intellectually rather than emotionally because you may feel daunting. Or you could say, hey, look, maybe the fact that we're finite and temporally bound isn't what matters most because it's like going to a suffering child and saying, oh, that doesn't matter that the child's being tortured by some serial killer. It's finite.
Without going into great detail, there certainly have been periods of my life, luckily they've not been incredibly long, but there have certainly been periods when I wasn't exactly sure how to find my way out of the dark space.
Ultimately, what really helped me was, along the lines of what you're saying, to blend the human emotion, which can be terror of mortality, that can be a sense of insignificance against the cosmic order, but to blend that with a recognition that, sure, we may be insignificant, but we
As a species may have figured out how the universe.
began and how it evolved and we may have figured out what laws of physics are in operation both here but also throughout the entirety of an infinite cosmos. We may have figured out laws that are relevant not just today and yesterday but perhaps relevant all the way 13.8 billion years ago and may continue to be relevant a hundred billion or a trillion or who knows how many years into the future.
And so if you allow yourself to feel part of that human journey and that human achievement, I have found that that can assuage some of the darkness and make one feel a connection to a larger cosmos.
And that connection to that larger cosmos for me has certainly helped to pull me from a place of smallness and feeling of darkness and insignificance to at least a connection that ameliorated those qualities and those feelings. Approximately how old were you when you were going through this period, if you don't mind me asking? You know, it's a good question, you know,
Certainly there was a time in my 40s that I can point to. There were episodes earlier, like right after college. I went through kind of a rough spell there, but it was thankfully relatively short-lived. And so it's been periodic, but it hasn't been debilitating.
And when I look at the things that I've done that I value most, I can't help but think that those periods were pretty vital toward being able to do the things that I did. So life is a whole package, right? And that whole package, for some, will involve periods that are less comfortable than others from this perspective.
Was it mainly the paltriness of existence or did you feel worthless as a result or for some other reason? And apologies if it's getting personal, but it's just that many people, including myself, like it's super helpful to see people that you look up to as a hero intellectually, especially going through what is common and emotional. Yeah, you know, it was definitely wasn't feelings of worthlessness. In a sense, it wasn't quite
that personal. I mean, obviously it was a very personal sensation and a personal challenge to overcome certain things that made it difficult to feel happy and to feel alive. But it was never a sense of, I, Brian Green, am worthless. It was more a sense of, oh my God, like, how does one live with the understanding
of the fact that apparently we are just the random output of random conditions being guided by a particular set of rigid mathematical rules. And if you think about that cognitively, it's kind of interesting and quirky. But if you think about it emotionally, it can really take you to a different place.
And for me, as I was saying before, I think the key to going forward was to not be terrorized by those realizations, but find a way within those realizations to feel a deep gratification. And that's a place that I've been able to get to, but it's relatively recent getting to that place. It's not as though it's a
19 year old or a 20 year old, this was something that was right there. And so it really is tying together the emotional and the cognitive into a narrative, a story that at least for me as an individual leads me feeling deeply connected to a wider reality and no longer feeling that sense of foreboding at the apparent
Is it possible to find meaning in disconnectedness? I often hear that connectedness is associated with meaning, but is it possible? Do you see a way that you could be too connected and you feel like, okay, let me just back off a bit. Well, it's a funny thing that you frame it that way because anybody who knows me personally would not consider me connected in the usual sense. I don't spend an enormous amount of time
with human beings outside of my most immediate family. My kids and wife like to joke of the lack of human contact that I have beyond a fairly small group. So I'm not talking about connection in that sense, although for some people that connection is utterly vital and utterly central to their being.
I'm talking more of a kind of cosmic connection, a feeling of being integrated into a wider reality because we're made of the very same stuff as everything else in reality. We're guided by the very same laws as everything else in reality. We emerged by processes that stretch from the beginning until today as every other structure in the cosmos has as well.
And so if you take that in fully enough and in the right light, it makes you feel part of the fabric of reality. And I think that's the connection that to me is the one that has proven to be the most important. Have psychedelics informed either your physics or your metaphysics? I can't really say. In fact, it's not completely clear to me whether or not I've actually ever had a psychedelic experience. No doubt you're referring
to the fact that in some more recent interviews I've opened up about certain experiences that at the time were absolutely terrifying. And in conversation with people who know far more about this arena than I do,
Their view is, you know, anything that takes your mind to a different place that ultimately you learn something from fits within the genre of exploration of altered states of consciousness. So framing it in that way, yeah, I would say that I have not had many such experiences, but the few that I have had, I guess gave me the deepest sense of how fragile
Ordinary cognition and ordinary experiences you introduce a few little molecules into the mind and these molecules radically change your experience.
I mean, that's mind blowing, isn't it? I mean, you know, cognitively, we all know that what's happening inside of our head is just the cascading motion particles going through our brains, neurons firing, it's all describable at the level of particulate motion inside of our heads. Okay, good. I got that cognitively. Now let me just throw in a few more molecules. And all of a sudden, the experience changes radically. And so everything that that we
usually think of as defining reality, which is our experience in an intuitive level, can be not completely off kilter through some molecules. And that's a beautiful recognition. And it opens you up to the realization that our experience is not tapping into V reality. Our experience is taking a reality
and interpreting it and molding it and shaping it in a manner that our brains do because of how they form through evolution by natural selection across the eons. Our brains are the way they are because our forebears survived and they survived because their brains were in a particular configuration that allowed them to better navigate the environment than their competitors. And that brain interprets the world.
We can change that interpretation by introducing new molecules and that is a deeply profound and eye-opening experience. If you could solve one problem, an academic one, so not let's take off the table world hunger or peace and so on, which one, and so this includes the hard problem of consciousness or philosophical problems as well as physics ones, which one do you most want solved by you?
Well, it's interesting and part of my answer will depend on what the answer is. So I think that the solution to the hard problem of consciousness, I suspect it's not going to be very interesting. I suspect that the solution to the hard problem of consciousness will be consciousness just is.
It's a quality that emerges when matter takes on a particular organized form and undergoes certain very orderly and organized procedures and phenomena. And if that's the answer, and I think that is likely to be the answer, then count me out in terms of wanting to solve it. I think that may be the solution. If it's more interesting than that, if there's some consciousness field that
you know, various religions talk about or, or something that we can't even imagine. And that's the root of consciousness. Yes, then I'd love to be part of the journey to solve it that way. But assuming that it's the more boring, but nevertheless, you know, profoundly important solution on what the heart problem is, then the other questions that I would really love to be part of finding the solution of is, what is time?
Is it just a secondary feature of the world that we human beings find useful in order to organize our perceptions of the world? Or is time more fundamentally woven into the fabric of reality? Is there a realm of reality in which there's no conception of time?
because the conditions simply have not gelled to the point where a conception of time can even emerge, or is there always a notion of time because it's just fundamentally part of how reality is constructed? I'd say that would be the one big one. And then, allied with that, you know, look, I'd love to know what the unified theory is, right? I'd love to know what
A thousand years from now, kindergarteners are going to learn in their course on Unified Field Theory, if that's the answer, you know, what is it and where does it come from? We can have a final theory, whatever it is, general relativity plus quantum, or maybe it's radically different, but whatever that ultimate theory is, where did it come from? Did someone in some
super simulation dream it up and we are just living out or where in the world do these fundamental laws and regularities and patterns come from in essence really why is there something rather than nothing i mean can't really get deeper than that and by nothing i don't mean you know empty space i don't mean nothing in the sense of a void i mean truly nothing
Do you think that a true toe or a good toe is one that explains itself?
Whenever you talk about a theory of everything, and I will frame it that way, I never use the word toe myself, but whenever you talk about a theory of everything, you have to say to yourself, what is embraced by everything? Usually when we physicists throw away, throw around, not throw away, when we throw around the term theory of everything, we usually mean a very limited everything. We usually mean the particles and the laws.
You know, the ingredients and the rules, that's what we mean by everything. But given that one can say, but why are there any particles? Why are there any rules? And so yeah, your way of framing it that if that theory of everything could somehow establish its own inevitability, if that theory of everything somehow has built within it,
That the lack of existence of that theory of everything would somehow be itself a logical inconsistency. So that reality could not have this theory of everything because reality is, we believe, in some sense, consistent. That would be deeply compelling.
Dyson conjectured that the Gödel incompleteness theorem or one of them applied to physics and so we may never know a toe. I don't recall his argument but I'm sure you've heard an argument akin to this. Can you spell it out for the audience and then where do you stand on it? You know, I have to say I have struggled myself for a long time to really know or at least have a feel for the relevance of Gödel's ideas.
when it comes to the laws of physics. And there was a time when I tried to convince myself that because Gödel's theorem itself relies upon assumptions, could we modify the assumptions in such a way that
the new assumptions could be relevant to the universe but the conclusion that girdle came to would no longer be relevant because the assumptions had changed and there are a handful of relatively straightforward ways to do that and frankly i don't even haven't thought about it in detail in quite some time but i i remember going through and say aha all we have to do is
Imagine a universe in which this is not true, and that universe could be our universe, like paracompact logic. I mean, there are ways in which you can go beyond the limited set of assumptions that Gödel had. And so I more or less have convinced myself
that Gödel's ideas need not imply that we will somehow fundamentally be in an undecidable situation when it comes to understanding the deep laws of the universe. It doesn't mean that Gödel's ideas might not apply. They could, but they don't have to. And with that realization, I became less interested
in and really puzzling because now we're in a realm that's so esoteric and abstract relative to the kind of concrete problems like what's the dark matter and what's the dark energy and you know is there just a unified theory of the particles of matter that we have discovered it just felt
20 steps removed from those kind of deep but really hands-on questions that I haven't spent a whole lot of time thinking about since. Speaking of time, do you believe time to be, well maybe you don't, let's not say believe. When you were playing with some ideas earlier and you're saying well time may be emergent, do you also believe space to be emergent? Do you believe space time itself is emergent?
Yeah, I mean, if time is emergent, it's hard for me to imagine that space is not emergent, too. Again, anybody who's spent a little time thinking about the insights from Einstein on recognizes that space and time are so deeply and intricately interwoven into the fabric of space-time, that sort of
Pulling one apart and imagining it has different properties, space and time have different properties, it's not impossible, but it does fly in the face of pretty much everything we've learned in the last hundred years. So I certainly do envision that if there's a realm of reality in which time does not apply, because as we were saying before, the conditions haven't yet allowed for a conception of time to emerge, the same would almost certainly be true of space.
So the real way of saying it is, is there a realm of reality in which there's no conception of space time? And it's hard for me to imagine what that is, but that's because I've got this brain that is constrained by what my ancestors did. And that brain is one that is so tied to a conception of reality.
in which space and time are the architecture within which events take place, that it's really hard for us to think about a reality in which there isn't space-time. And so I wish I could give some really good example or insight into what that would be like, but it would be some kind of reality in which the language that we use would not talk about when things are happening,
And the language that we use would not talk about where things are happening. The language would somehow be beneath that, more fundamental than that. And it's not that scientists don't have some ideas for what this might be like, but I'd say that we do lack the deep picture and the deep story of how we would really articulate and navigate a reality absent space-time.
Have you had a chance to go through Wolfram's theory, his project on physics? I wish I had. Steve's a great guy and he's a friend and we talk about things on occasion and I wish I had more time to spend with him because it's always illuminating when we do spend some time together. But I've not
I don't feel like I fully grasp the approach that he's taking. Why? I can absolutely throw this on myself. It could well be limitations in my own thinking and limitations in the amount of energy and effort that I've expended to understand his approach more fully.
I get stuck on trying to really understand whether the formalism, as he envisions it, is it actually fundamentally different from the more traditional formalism? He would say, yes, as far as I can tell. But as I have looked at it on occasion, it has struck me that it's not obvious to me that it is as different as he suggests. And again, I could be wrong on this.
And it could be that I just haven't put enough effort or energy into it. I'm glad that he's pursuing his approach. It's not within the confines of the traditional established environment is not doing it inside of the physics department or math department.
You know, he has the resources and the creative energies to make his own environment and to find his own collaborators and more power to anybody who has the capacity to do that. Whether it's going to bear the fruit that he envisions, I don't know, but I'd say the same thing about what we're doing here. Like we've been beating down on string theory, you know, since
You know 1984 at least you know the the big first revolution but since 1968 if you want to go further back to the first glimmers of string theory and where are we now 2023 that's a lot of years right so you can say the same thing you know so so i don't feel qualified to really judge the approach but i i just feel that i haven't fully wrapped my head around whether or not it's
What progress has been made in string theory in the past two decades?
a connection between gravity and quantum mechanics that I don't think would be sufficiently appreciated 20, 25 years ago. I mean, take my book just as one moment in time, a snapshot in the elegant universe. I was published in 1999. And in that book, I very clearly lay out there's this theory called general relativity describing gravity, the big stuff,
I lay out how there is this other theory called quantum mechanics, describing the small stuff, and we want to put them all together, have a unified theory of the big and the small, but we're having trouble doing that. And then I go into the book and how string theory seems to be making progress in putting the big and the small together. If I was writing that book today, and in some sense I am, because I'm adding a chapter for the 25th anniversary of the elegant universe,
And one of the things that I'm emphasizing is there's now a lot of evidence that gravity and quantum mechanics in some sense are kind of the same theory. They are already in some strange sense combined. And this was completely unexpected based on anything that we knew 20 or so, 20 plus years ago.
So within, for instance, general relativity, there are these structures you made reference to one of them earlier called wormholes, which are tunnels in the fabric of space going from one space-time location to another through a kind of shortcut. That's general relativity. In quantum mechanics, there's this weird thing called quantum entanglement.
where two widely separated particles can act as though they're right next to each other, even though they can be on opposite ends of the universe. And really nobody thought there was a connection between these two ideas until people like Lenny Susskind and Juan Maldacena and a variety of other influential scientists, too many to name them all,
gave evidence that in some sense wormholes and entanglement are kind of the same thing. They kind of feel the same if you think about it. Wormhole, it's connecting one point in space time with another through a shortcut. Entanglement is connecting one particle in space time with another particle in some sense through a shortcut because they're acting as though they're right next to each other. And so this is the beginning, the tip of an iceberg of a deep and very powerful story.
which is showing that structures in general relativity and structures in quantum mechanics are already deeply connected and deeply entwined. And so the unification program may ultimately not be described
in terms of putting gravity and quantum mechanics together, the way I described it, and many did, of course, in the earlier days. But it may be more deeply understanding general relativity, more deeply understanding quantum mechanics, and more deeply understanding how they are part and parcel of the same theoretical structure. So the recent results by Google of the ER equals EPR, is that overhyped? Is that underhyped?
I also can you explain the results to the audience? Yeah, so this is a little bit controversial. There have been some feathers ruffled by some recent activity. And what the idea is that if, for instance, what I said a moment ago is true, that there's this deep connection between wormholes and general relativity and entanglement in quantum physics,
Then a number of influential physicists pointed out that by doing certain calculations on a quantum computer, you would in some sense be simulating a wormhole in general relativity, because quantum computing is all about leveraging quantum entanglement between qubits. And so
There was a recent paper and it was making use of the quantum computational capacities at Google and I think the kerfuffle is more about language than anything else because some of the folks who were carrying out this work, this is like Maria Sparoppolu and Joe Licken and Daniel Jefferson and so on, there was at least some
Part of the
they were modeling a wormhole or kind of simulating a wormhole as opposed to actually creating a wormhole. You know, one comment I saw by the, the really deeply insightful quantum computational physicist, Scott Aronson was saying to say that you created a wormhole in, in undertaking this quantum computer simulation,
We'd be tantamount to saying that every time you drew a wormhole on a piece of paper, you created a wormhole. It's like, how do you distinguish between modeling something and the something? And I think that distinction, perhaps according to some, was lost in some of the
ways in which the results were articulated. But putting the controversy or the bit of kerfuffle to the side, it's a very, very interesting piece of work in which doing a quantum computation and appropriately interpreting it, you could see within that computation the kinds of phenomenon that you would associate with a wormhole.
And that's a beautiful thing because it now is a very concrete realization of what I was saying before in answer to your question of what's new in the last 20 years. What's new is here you're doing something that's purely quantum mechanical. You're carrying out a quantum computation on a quantum computer. And then by analyzing it appropriately, you're saying, oh my God, look in there. We're seeing exactly what we'd expect in a particular kind of wormhole.
And so the connection between general relativity and quantum mechanics becomes that much more apparent. The uncontroversial statement is that they've simulated a wormhole or modeled a wormhole. I don't want to speak at a turn because I don't want to speak for either side of this debate. But I would say that I think that's the linchpin of some of the controversy. And so it feels less important to me
When thought of in that light, I'm just interested in how curious and wonderful it is that general relativity and quantum mechanics are rushing up against each other in a manner that we really wouldn't have anticipated with the level of our understanding 20-25 years ago. Okay, now speaking about what's overhyped or potentially underhyped, what are some of the applications of category theory to high energy physics?
Oh goodness gracious, wrong person to talk about. You know, I've read some of the papers on this stuff, but I don't feel sufficiently expert to weigh in on that at all. So, sorry. All right, no problem. So, there are different toes like Garrett Leesey's, like Eric Weinstein's, and Peter Wojt, and I'm curious
Have you had a chance to look into any of those, like Lisey's E8 or Eric Weinstein's Geometric Unity or Peter White's Euclidean Twister? I didn't even know that Peter White had put forward a particular idea, so again, I'll have to claim ignorance on that front. But the Garrett-Lisey stuff, unless there's something radically new in recent years, certainly when he first gained a little bit of attention for the ideas he was putting forward,
I have to say I relied upon a good friend who I've known for 40 years, perhaps Jacques Dissler at the University of Texas who did a wonderful series of blog posts
that
Again, in any detail, so I can't comment. But I guess, you know, I've not I've not encountered anything beyond quantum gravity, which I don't work on. I don't I don't study. But I certainly respect the results that that community has put forward. And, you know, while some people take exception with certain things that Lee Smolin, one of the leaders of that field has
said about string theory. I sort of don't take those things personally and I focus more on the ideas and I think they've done some some wonderful work.
in understanding connections between general activity and quantum mechanics. But one would say that I'm biased. I don't see anything that's achieved the level of refinement and sophistication and insight that string theory has provided.
Nothing that I've seen remotely holds a candle to the kinds of insights, especially the ones that we were just talking about a moment ago, which are both deep and surprising. But even before that, the capacity to have a theory that is quantum mechanical and has general relativity embedded and is able to have within it the symmetries
the standard model of particle physics and the particles in the standard model and naturally is within their theory that's able to give us insight into things like the entropy of black holes which again you know loop quantum gravity has its own insights but I think the string theoretic ones are deeply impressive and so there have been so many small achievements
along the way. Yeah, we haven't gotten the big one, which would be an experiment that somehow reveals that this approach to nature is the right approach. But there have been so many achievements over the course of the last 50 years that I haven't felt compelled to look for another approach because we've got a rich, wondrous, deep, compelling theory that we're in the midst of unraveling.
And so that feels to me a very strong pull relative to, you know, somebody comes up with some idea, raises their hand and said, now look at what I've got. And that to me, I'm glad there are people who are doing it, but it's typically not the thing will grab my attention away from the focus work that I'm doing and that we're doing as a community.
What would be the other people in the ring that you see as competent boxers that are opponents to string theory? Or perhaps it's not a competition. They're all claring for the same. They're all fighting toward the same goal. So what else is there? So there's loop. But again, that's not a toe per se. It's quantum gravity approach, unless there's some other development I'm unaware of. Do you mind listing some? No, I wouldn't. I guess first of all, like I said before, I typically don't use the language.
It's not because of the abbreviation of the acronym. I think that the whole conception of everything is an odd one. So when you talk about loop quantum gravity, you know, if you have a theory that is able to embrace general relativity and quantum mechanics in some calculable and coherent mathematical form,
That's huge, right? I wouldn't say that it somehow is subordinate to string theory because within string theory, you know, perhaps you can also put the standard model particle physics most direct, you know, if loop quantum gravity works, you will be able to use it as an overarching framework and then put in quote unquote, everything else put in matter, I have no doubt that that this is a
a potential future if indeed loop quantum gravity is the right way to go. So I wouldn't somehow diminish it and say, well, string theory is a theory of everything and loop quantum gravity is not. I don't think that way at all. I mean, to me, the big question is, you know, what do we do about general relativity and quantum mechanics? And what's becoming clear, as I mentioned before, is that the idea of trying to meld them together may itself have been somewhat wrongheaded.
that may already be melded together and it's up to us to understand how that melding actually works. I mean, as you know well, once quantum mechanics came on the scene in the 1920s, there was this approach developed called quantization, where you took ideas from the pre-quantum world, classical physics, and you found a kind of algorithm
For making them quantum mechanical, that algorithm was called quantization. Take Newton's ideas, make them quantum mechanical. And that was the rhythm. That was the approach that we took for a long time. That may not be the right approach. It may not be you take Einstein's ideas of general relativity and you quantize them.
They may already have quantum mechanics within them. And that that's the deep, new and exciting insight. So he asked me sort of what are the sort of competitors or candidates? You know, well, certainly I consider, as I mentioned before, the loop quantum gravity community. Many colleagues, many friends in that world, and I respect what they are doing.
I think as I mentioned that the string theoretic approach has achieved more and it feels like it's giving us more surprising and detailed insights but no doubt people would say partly your view is colored by the fact that you know since I was a graduate student that's been more or less the domain within which I've walked. None of the other ideas that I've
scene described and again I full well say I do not investigate them all because I don't have the time but I've not seen anything else that rises to that level of achievement or sophistication. The reason behind my question is that I'm working on a paper with a colleague Carlos Zapata where we're going to do an inventory of the candidates for unification attempts between gravity and quantum mechanics so maybe you don't want to call it toes, whatever.
Let's just call it a toast for the sake of this. And then also some desiderata on the side, like does it explain so and so on? And there's some uncontroversial list on Wikipedia of the outstanding problems in physics and putting a checkmark like a matrix with one on the X axis, one on the Y axis. And so I wanted to know, well, I'm asking different physicists and also mathematicians who work in physics, what are the different candidates that should go there?
And I know that you mentioned that there are several people who raise their hand as difficulty can't follow every single one who says I have a toe. The toe by Lisey and and Weinstein and Eric Wolfram. They're of a different quality than the average person who emails and says that they have a toe. That is in mathematical sophistication, maybe not rigor. But hey, the elements of a toe, even quantum field theory is not entirely rigorous. But the point is in terms of mathematical sophistication, they're in a different league.
So I'm curious what else goes there. And then I wanted to do a waiting, like, it's a bit unfair to say, so 32 solves seven out of the 15. But Wolfram's only solves five out of the 15. However, Wolfram's working on it in a basement, maybe a basement in a lovely house, but like an abasement. And, and there's, let's say 1000 people working on SL 32 across decades or a heterotic eight or whatever it may be. So then I was like, how do I do that waiting? And then, but anyway, so it's a fun project.
And I just wanted some help with it and I wanted to hear what your thoughts were and what else you think I should consider putting in it or not putting in it. Look, I mean, it sounds like fun and I'm sure I enjoy reading it when it comes out. But the interesting thing is to most researchers in the field, the work is all about the details.
And you're right that we all receive these letters in the mail and sometimes they're actually kind of heartbreaking. I've gotten letters from people who've been in that basement that you just made reference to, not a particularly nice one, I would imagine, working out the final theory of everything. I remember one gentleman wrote to me and I think he was on the level. He was saying how he's been working on this for 20, 25 years.
His wife left him, his kids left him because the only thing he cared about was working out this theory and he finally had the theory and it sent it to me. And it looked like every other theory that I get through that particular idiom. All sorts of graphs and lines and interconnected shapes and you're like, oh my God, you know,
This is probably insane. I mean, not insane in some medically verifiable sense, but it's deeply sad that someone who has the same urge that we have, right, wants to figure it all out, is somehow likely being misled by certain kinds of patterns or certain kinds of geometrical shapes that really have no bearing on the final answer. And the number of times you get
communications of the sort where it's all about working out ratios of like pi to the ninth divided by e to the seventh you know time you know and and and they work out to like 12 or 15 decimal places and they find some pattern in the numbers and yeah it hurts inside to imagine someone spending their life doing something like that which is meaningless and so yes that category of work is quite different
from any of the other ideas that you've put forward. But in the end of the day, people vote with what they work on. And string theory has attracted a great deal of people to work on it. And by string theory, I mean now something broader than what I would have meant, say, in 1990 or 2000. String theory now is
any work that uses the ingredients or the insights or the mathematical formalism that was part of the early development of string theory. So now, you know, people who are working on connections between gravity, general relativity and quantum mechanics and tangleman as we described before, would I call that string theory per se? I don't know. It would have been
very unfamiliar to a string theorist, say from 1980, but that's what progress is. It's wherever the ideas lead you. So as a community, it's hard for me to compare anything to the string theory community for the level of insight and the level of achievement. So sure, I mean, it's nice to lay out like in a matrix in a chart, you know, the various approaches that that serious
scientists as opposed to perhaps untrained folks in basements what serious scientists have been focused their attention on but I really don't think anything comes close to what the string theory community broadly defined has achieved and again I do have great respect as I mentioned for the loop quantum gravity community but none of the others for me really are developed to a point that are worthy
of exploration and attention, at least not yet. What advice do you have for people who are interested in physics, like seriously interested in physics, but aren't able to go to university for whatever reason? Maybe they're older now and they feel like they don't want to go back, they have not enough time, or they just don't have the money or whatever life circumstance. Yeah, well, look, you know, I never want to discourage people. There may be a Ramanujan in our midst.
You know, someone whose level of perspicacity is so off-scale that they don't need the traditional training and they don't need the traditional environment and then they can produce things that, you know, I forget exactly the quote, but mathematician G. H. Hardy, when looking at some of the theorems that Ramanujan had sent him, said something like, you know, if these are true, he's the greatest mathematician.
If these are not true, he's an even greater mathematician for having thought them up when they're not actually true. I mean, you know, so if there's somebody like that, wow, more power to them and they can pursue these kinds of ideas on their own or maybe through brief communications. But for the vast majority of people of the sort that you're describing, it is really tough to do this outside of a community of coworkers.
I mean, the way we physicists typically work, you know, in my office at Columbia, students and grad students and postdocs and seminars and informal conversations. And you read this paper and you hear that idea, you talk to that person, you start to develop this collaboration, that collaboration. It's just really hard to do physics without that. And so if one is not in that world and one is somewhat older, it's really tough to break in.
And for most people, they don't have the financial resources to just give up their life and go back to school, especially with the fact that, I mean, you know, maybe things are changing, but, you know, it's tough to get a faculty job if you get your PhD at like 70. It's just unlikely. I'm using extreme numbers to avoid anybody like jumping down on my throat and some ageism, you know, but you know what I'm saying? The typical route,
The typical route is someone gets their PhD at a relatively young and society views it as more energetic, fertile age, and then they get a faculty job and they're often running as part of the community. And when you, when you delay that, it's really, really hard. I mean, I have known, and you know, individuals who loved, I remember I'm thinking of one guy in particular loved mathematics.
And he went back and got his PhD at a relatively advanced age, which wasn't old, but relatively advanced age compared to the norm, and got himself a really nice teaching job at a university. And as far as I can tell, I haven't spoken to him. I was quite happy because he's spending time in the community of ideas that he finds most exciting. But it's tough. That's rare. That's really tough.
So, you know, I guess the advice would be maybe you can find enough gratification from reading about the ideas and maybe going to a local university when they have a seminar series. Maybe you can, you know, and maybe through that you can find inroads into your local community at a local university and maybe even begin some collaboration on some kind of project. But it's not an easy path.
and certainly not if one wants to make it their sort of career and for them to make a living from it. That's really tough if you're not in a traditional trajectory. What an analogy be if someone wants to learn martial arts? Sure, you could do so on your own. You can watch YouTube videos, but there is something about grappling with other people using your body with someone who is living rather than a wooden machine. There's something about the group dynamic or does that analogy fail?
You know, I think it's a really good analogy, and I think I may use it going forward. So thank you on that one. But because, look, the number of times, you know, I'm reasonably well-accomplished, right? The number of times when I've been working on something, I'm completely stuck. I try this, I try that, it's just not happening, right? Then I'll meet with a few people, you know, here at Columbia, we do chit-chat, talk, oh, boom, now we know where to go. Where did the idea come from?
None of us had the idea of going in to that exchange, but yet somehow in the midst of that grappling, if I go back to your metaphor, the potential idea emerged. And so without that, it's very hard to make progress. Have you ever collaborated with Ed Whitten? Collaborated, no, but worked
Right next to him, yes, in the sense of back in the 1990s, I was at the Institute for Advanced Study and we had an idea. I had a particular idea of something I wanted to prove that the fabric of space could rip and Ed is at the Institute for Advanced Study. I told him about this idea, thought it was exciting. I was working with a couple other people, Paul Asimov, Dave Morrison.
Edward started to work on his own version. Didn't take anything from us. He just went a completely different direction, but yet converged on exactly the same question. And it was among the most exciting times that I've had in physics because like we knew he was closing in on it. We were closing in on it. We knew that he's a million times smarter than we are. So we had to work a million times harder and faster to try to get there and not be completely scooped.
And basically at the same time, late in the fall, I guess, of 1992, it was, within days came to the same conclusion from completely different approaches. And so we were right, right there, you know, head to head. It was an incredibly exciting time. But yeah, he's again, you know, one of those figures whose intellect is just hard to fathom.
I was speaking to Richard Borchards and he said, Ed Whitten is terrifying. And I said, well, why? And he said that he puts out as side effects whole other fields like the Whitten invariance, like sideburns. You have to tell you, it's funny, a friend of mine was at the Institute for Revenge study over a summer.
And the place that kind of cleared out and I think Edward was there and this friend of mine was there. I won't give his name in case he wouldn't want me to share it, but they were kind of sharing a wall. Their offices were right next to each other.
And so my friend was slogging away doing his calculations, you know, hitting dead ends. And all through the summer, he kept hearing tap, tap, tap, tap, tap, tap as Ed was typing out paper after paper after paper as if he was just sort of sitting there. And the ideas were sufficiently formed that he didn't even have to write anything out. He could go right from brain to finished paper. And my friend was like, you sit there and you're like, what am I doing? Why am I in this field?
You know, I can't, I can't, but that's actually an important thing. There is a place where so many people can contribute, sort of back to the question we had before. While it's harder for the person who's not gone to graduate school or is working in the basement to really make that contribution, kids who go to undergraduate then go to graduate, there's so many ways for so many different people with so many different
levels of intellectual capacity and level of insight to contribute and to contribute in vital ways. And so you don't have to only be an Edward Witten in order that you advance the field. And so it's absolutely the case. How do you not feel demoralized if you're working on the same problem as Ed Witten or synonym for Ed Witten? So you work on a different problem or what? Or you try to collaborate? Look, I mean,
So I gave you one example where we were working on the same problem in a sense as Edward Witten and the fact that we got to the finish line at the same time is again one of those great achievements that I will always remember. For Edward, it was just another day at the office. But having said that, I think it's very important that you pick your problems carefully.
You don't want to take, I don't like to take a problem that every other physicist deems as the most important and they're all working on it. That's never been my approach. My approach has always been, I'm going to find that corner that appeals to me, that corner that I feel like I can, at my own pace, I'll work hard, but at my own pace, I can make headway and make progress.
and contribute something, bring it out to the world, and then maybe excite people to work on that. I mean, that's, you know, one of the big things that I did some years ago is called mirror symmetry, which was developing certain properties of higher dimensional spaces that are relevant for string theory. And when we were working on this, it was a really small community that was working. It was really us and one other group in Texas, Philip Kandelos and his group down in Texas,
And so it was really exciting. We were competing against each other, but we were in close communication. But it wasn't like a thousand other groups around the world were all battered and it's just us. And so, you know, we got ours, he got his results, our group got our results, he put it, people got excited. And then the field took off. And now like mirror symmetry has become a whole field of mathematics that has developed over decades.
I no longer even recognize the things that happen in this field because it got so mathematical and so beyond my particular interest, which is really from the physics standpoint, but that's a great place to be. Work in your own corner, come up with something, put it out there, start a field and then the field takes off and God bless everybody who works on it. Your current interest is time or one of them, the emergence of time? Yeah, I mean that is a big question though. It's not as though
You sit down at your desk and you're like, OK, where does time begin? It's not a question you hit head on. I think it's the kind of question that you hit obliquely. And for instance, I would imagine that this work being done on wormholes and quantum entanglement, taking general relativity and understanding its inherent quantum mechanical aspects, I anticipate that insight into a deep question such as the origin of time will ultimately emerge from that.
But not from a head-on approach, but rather from a more indirect approach. Do you agree with or find interesting Carlo Rovelli's views on time? He has this book, The Order of Time, and Lee Smolin has his own views too, which I believe is a realist, and then Carlo believes it's more relational or an emergent. And then Julian Barber. Yeah, so I think they're all interesting. Yeah, I think they're all interesting ideas. You know, I think that
Ultimately, the question of the fundamental nature of time is going to require scientific insights beyond those that we currently have. So I'm always interested to hear
thoughts on the nature of time and so rebellion the relational quality of space-time that resonates with me. I think there's definite powerful truth in there. I've seen papers of Lee's talking about the way in which time can emerge from an earlier temporal quality, a kind of way in which
The future is built from the present as opposed to already in some sense a temporal dimension being out there. I think it's quite interesting. Julian Barber. I remember being very excited about the initial ideas and then I read his book and there was one paragraph where I felt the heart of the idea was put forward.
And it felt to me that he'd redefined the problem for me in a way that didn't feel as interesting any longer. I don't know if there's been developments since then. So it's all just to say that, yeah, time is a big mystery. Always interested to hear people's take on it. But in the end of the day, I think it's going to take deeper scientific insight. And what's happening now in string theory, broadly defined,
Before we wrap, I have a choice for you. We can have a couple physics questions or a couple more philosophical questions. Do you have a preference?
You can do a blend, whatever you think is good. Alright, so I know that you haven't explored category theory much but have you explored geometric algebra or geometric calculus? You know, I have dabbled but not enough to feel like I can provide any insight compared to the people who really know the subject so I probably would save those questions for subsequent guests who are more in that space. Sure, sure. What is the
Swampland conjectures. The swampland conjectures have to do with the following question. When you have a theory that does a really good job at describing say the physics that we can see, low energy physics is the physics that we can see.
Does that theoretical description have what's known as an ultraviolet completion? That is, can that low energy physics be augmented into a theory that will agree with that low energy physics but work at arbitrarily high energies? Or is this just kind of an approximate theory that works at low energies but doesn't admit
an ultraviolet completion, ultraviolet high energy, doesn't admit a high energy completion. That is, it cannot be extended to arbitrarily high energies. And the Swampland idea is to delineate theories that may have a low energy incarnation, but don't admit a full completion to the entire energy spectrum. And the thought, according to some of the Swampland ideas, is that
The Swamp Plan is pretty big. Many, many of the theories that perhaps look like they may be candidates for theories that could be extended to arbitrarily high energies, they can't. They are fundamentally inconsistent. And that would be a potentially powerful idea, because after all, our goal is to winnow down the number of
candidate theories for the final theory and a final theory would work at any energy scale and if you can establish that a great many theories that look like they were contenders at low energies that they don't admit an extension to arbitrarily high energies then they get eliminated from the competition and so you get to winnow out a whole class of theories that don't
So what's meant by, you can take a low effect, sorry, a low energy theory and it works at the low energy, but then for some you may be able to augment them and then they're UV complete. What's meant by augment? What's a valid augmenting? So that what I mean is you can augment Newtonian theory to get special relativity. I don't know if like, does that mean Newtonian? Like, I don't know what augment means. Yeah. So, so usually
These ideas are formulated where you've actually got a mathematical formulation of a given theory, say perhaps even within string theory itself, and then you can simply ask, is this a self-consistent theory in the sense that you can use it, that very mathematical formulation, at arbitrarily high energies? And if you can't, then it properly should be
Consigned to the swampland because it doesn't admit an extension to or an application perhaps would be a better way of saying to arbitrarily high energies. And so, you know, this is an idea that Kumram Vafa and collaborators was, you know, instrumental in developing. And it, you know, I would say that it has flattened all of the
open questions when it comes to the theories like string theory but it has sharpened them because anytime you have a test in some sense for whether or not a theory is fully consistent works at arbitrarily high energies and I should say high energies mean short distances so does the theory work at arbitrarily short distances if it somehow is inconsistent at sufficiently short distances
That's a good thing for the project because now you can throw that theory away. Is consistency the same as self-consistency? Or are those separate? Usually. Well, usually. So unfortunately, our ability to probe the real physics of the real world at arbitrarily short distances is highly constrained by the equipment that we have. And so we'd love it.
if consistency meant short internal consistency but also consistency with observations that we might make of you know physics down to 10 to the minus 25 or 10 to the minus 30 centimeters you know that would be beautiful but but because our ability to probe such realms is limited by our technology for the most part yeah we're talking about internal self-consistency
Okay, firstly, is internal consistency the same as self-consistency, just so I can get the terminology clear? Yeah, I mean, it's just a statement of as a mathematical structure, do you find any divergences? Do you find any incurable infinities or other mathematical maladies? Do they emerge
When you try to apply this theory to arbitrarily short distance or arbitrarily high energies. And yeah, you're not talking about observation at this point because you don't have the observations.
Sorry, a self-consistent theory would be UV-complete and a UV-complete theory would be self-consistent or no? If you have a true UV-complete theory, almost by definition, it's consistent because the completion means that you've been able to formulate the theory in a way that you can apply to arbitrarily short distances, arbitrarily high energies, but UV-complete is. Let's end with your thoughts on simulation theory.
It's certainly the case that as computational systems have become more and more sophisticated, their ability to simulate the real world seemingly is getting better and better.
We see this with going from video games to the most sophisticated virtual reality. And so certainly one can imagine that at some point in the future we will have computational systems that are so sophisticated that they are able to have within them collections of bits and bytes running around that
May themselves have self-awareness. Now, that's the big unknown. Can you have a computational system that is itself self-aware, that it has some sort of consciousness? That goes back to the question that we started with early on. I don't know the answer to that, but let's assume the answer is yes. Big assumption. Let's assume the answer is yes. Well, then you're in an interesting circumstance because you can ask yourself,
How many real universes in the sense of solid tables and chairs are there? Well, we're kind of aware of one, and it's very hard to create new ones. If I challenge you to create a new real universe, you don't know how to do it. Create a new Big Bang, nobody really knows how to do that. But if I ask you how many of these
Simulated universes are there. Again, assuming that we've gotten to the point, say in the future, when we're able to simulate worlds of the conscious beings, there could be a gazillion simulated universes. You know, some kid just comes home late at night and flips on the computer and says, let me just simulate one more universe with these and these parameters, just flips it up and the computer just simulates it. And within that simulation are further conscious beings. So then the question to ask yourself is what's the likelihood
that right now we are in a simulation. And if you sort of play the odds in the most naive way, you say, well, there's only one real universe, but there are gazillion, gazillion, gazillion of these simulated worlds. And so the odds would seem to suggest that we are in a simulated world just by sheer force of the numbers and probabilities.
So do I believe that? Do I think that we are in a simulation right now? I can't say that I do. If you're to really challenge me why I don't, I don't really have a good response beyond the fact that I've never seen a simulation that can do this. But, you know, that may simply be that the simulator is so good that the simulator is hidden from me. The fact that I'm in a simulation
And I agree that if I extrapolate from where computation was 40 years ago to where it is today, sort of exponential growth in its ability to do things that seem real, then, you know, don't go 40 years hence, assuming we don't blow ourselves up, go up a thousand years hence. And now you can really imagine that there are these simulations and we could well be in one of them. So
i don't feel like i have a strong reputation of the possibility that i'm in a simulation but
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Thank you so much for your time. It's been a pleasure. I do have a last question from Charlie from the Institute for Arts and Ideas. He sent this to me and he's like, Kurt, can you please, you're speaking to Brian, I would love if you could mention this. So I'll chat it here and I can say it aloud. If that's alright? Yeah, sure. I'll say it aloud just so that you can read it.
Charlie Barnett from the Institute of Arts and Ideas says, hi Brian, almost a year ago to this day you were featured on a panel at the IAI, so the Institute for Arts and Ideas with Michael Shermer, Sabine Hassenfelder and Eric Weinstein. Eric Weinstein who was a mathematical physicist at Harvard said that string theory had a terrible culture in the 1980s that was in the process of resolving itself
In response to this, you sympathized and said that there was a sense of unreasonable exuberance that many thought string theory was the final theory, but it also seemed that Eric was slightly exaggerating how bad the culture was. What do you think he was referring to, and could you maybe comment more broadly about how one can ensure that bias doesn't creep into scientific theories? Yeah, I mean, you know, briefly put, there
was a sentiment in the eighties. I mean, I was there as in thick of it as a graduate student, mostly, not as a faculty member. And there was a sentiment that we were approaching the end of physics. It was naive, but it was genuine. It wasn't as though people were making it up. I mean, you can imagine, well, you can, but if you weren't actually part of it, perhaps one can't really feel
the visceral excitement that had taken hold of a segment of the physics community. I mean, there I was a graduate student at Oxford in 1984, 1985, and every Wednesday or something like that, when the preprints were finally delivered to the physics department, the graduate students, two others and myself in particular,
We would like tear open the envelopes to see the next result. And we take that paper and compare it to what we were doing. We'd go up and we were working like, you know, 15 hours a day. You know, I go to sleep at two in the morning. I'd wake up at seven. I'd ride my bike to the physics because it was just like, oh, my God, like it was all coming together, which is all just to say it was genuine.
The excitement was genuine, but the downside of that kind of excitement is if someone's not working on string theory at that time, I can well imagine they feel like a complete outsider, that they're completely excluded, that nobody cares about what they're working on or what they are doing. And I know people
who have described that experience to me. And I don't know if that was Eric's experience or if there was something particular that happened. I just don't know. I don't know him personally. Sure, I've done that event and so forth. But I do know people who, from a more personal perspective, have described how alienated the excitement in the string theory community made them feel back in those days. And so I get it.
And I wish it wasn't that way. But I guess the point that I was making last year and the point that I make again here, it wasn't malicious. It wasn't like folks said, let's exclude everybody else who's not working on this sacred meeting. It wasn't like that. It was just that people were so wrapped up in what they were doing and so excited by what they were doing that there wasn't a lot of the energy or time left in the community to pay attention
to things that were happening in the surrounding. And when it came to jobs, there were real implications for this. You know, in those days, more string theorists got the postdocs and got the faculty jobs because of the excitement. And you can well imagine that somebody who was working hard and doing really good work, but outside of string theory, maybe said, let me in. I want a job. Like I want a postdoc. I want to get it. And I totally
empathize with that. But it's just that when it's framed as those string theorists were like a malicious community that were sort of barring the doors against it, it wasn't like that at all. It was just coming from whatever Alan Green's, you know, irrational exuberance, you know, it was exuberant. And was it irrational? Not irrational, but it was perhaps a little too much. Because the more
seasoned researchers and physicists at that time knew that ultimately the excitement would die down and the theory would need to mature and be developed. And that's what we've been doing. So I think that's sort of my best answer that it was coming from a good place. It wasn't coming from a place of exclusion.
Yeah, I need to be a little bit more active in that realm.
Sometimes I use Twitter. My kids tell me I should use Instagram. Maybe I'll start doing that. I don't know, TikTok. Maybe I think I'm too old for that. But, you know, the World Science Festival is probably the best place. We are creating all sorts of, I think, really interesting content. And so people should sign up for the World Science Festival newsletter. And that's certainly where a lot of my focus has been in terms of bringing science to the public. And yeah, if you happen to be in the Toronto area on the 26th,
And you said next week is relative to when this goes out. Yeah, come by to the program at Roy Thompson Hall. I think you'll enjoy it. It's sort of an evening exploration of the universe from sort of soup to nuts. Great. And just to be clear, that's January 26th, 2023. Evening time, I'm assuming. Whatever it is, I'll put it on screen. Yeah. Is that being repeated? That talk being repeated at a different city that you can promote?
I'm just trying it out in Toronto to see how it goes. If the reception is good, then I can imagine doing it elsewhere. If you find yourself in New York at the end of May, we're going to do our first live World Science Festival since 2019.
Because of everything, you know, we've gone fully digital, but we're going to go live again in the end of May of 2023. And that's coming up in, you know, five or six months. So it'll be a fun time in New York. And I'm going to do this program in New York as well. OK, I see. I see. OK, yeah, well, it's definitely keep me apprised about the World Science Festival because as Toh grows, sorry, the theories of everything channel grows, maybe there's something I could do to help promote it. And it was a pleasure, man.
The podcast is now concluded. Thank you for watching. If you haven't subscribed or clicked on that like button now would be a great time to do so as each subscribe and like helps YouTube push this content to more people. Also, I recently found out that external links count plenty toward the algorithm, which means that when you share on Twitter, on Facebook, on Reddit, etc.
It shows YouTube that people are talking about this outside of YouTube, which in turn greatly aids the distribution on YouTube as well. If you'd like to support more conversations like this, then do consider visiting theories of everything dot org. Again, it's support from the sponsors and you that allow me to work on toe full time. You get early access to ad free audio episodes there as well. Every dollar helps far more than you may think. Either way, your viewership is generosity enough. Thank you.
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"text": " The Economist covers math, physics, philosophy, and AI in a manner that shows how different countries perceive developments and how they impact markets. They recently published a piece on China's new neutrino detector. They cover extending life via mitochondrial transplants, creating an entirely new field of medicine. But it's also not just science they analyze."
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"text": " Think Verizon, the best 5G network is expensive? Think again. Bring in your AT&T or T-Mobile bill to a Verizon store today and we'll give you a better deal. Now what to do with your unwanted bills? Ever seen an origami version of the Miami Bull?"
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"text": " Today we talk about consciousness, time travel, string theory, quantum gravity, and wormholes. Brian Green is a theoretical physicist, a mathematician, and a string theorist, who is best known for his work on mirror symmetry and flop transitions. Brian's also a professor at Columbia University, as well as the chairman of the World Science Festival, and the author of several popular books on physics, including The Elegant Universe."
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"text": " This was a purposefully desultory interview which brought us both to uncomfortable ground comfortably. You'll see what I mean. My name is Kurt Jaimungal. I have a background in mathematical physics. This podcast is called Theories of Everything. It's dedicated to the exploration of theories of everything from a theoretical physics perspective, but as well as exploring the role consciousness has to the fundamental laws of nature."
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"text": " Each sponsor, as well as the patrons, improves the quality of the videos drastically, it improves the depth, it improves the frequency, and it goes toward paying the staff, for instance, someone who's editing this full time right now, and then we have an operations manager. In that vein, I want to thank today's sponsor, Brilliant. If you're familiar with Toe, you're familiar with Brilliant, but for those who don't know, Brilliant is a place where you go to learn math, science, and engineering"
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"text": " Through these bite sized interactive learning experiences, for example, and I keep saying this, I would like to do a podcast on information theory, particularly Chiara Marletal, which is David Deutsch's student has a theory of everything that she puts forward called constructor theory, which is heavily contingent on information theory. So I took their course on random variable distributions and knowledge and uncertainty."
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"text": " Professor Brian Green, it's an honor to speak with you. I've been researching you since I was young and also as I've gotten older, it's an honor. Thank you for coming on. Thank you. Thank you so much. What have you been working on in the past year and what do you hope to accomplish in the next year and this year? Well, I've been working on some strange things of late, which I'm almost afraid to talk about, but since they've been published, I guess I shouldn't at all hold back. But it sounds a little kooky."
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"text": " It sounds like the kind of things that I received in emails and crank letters for the past 30 years. It has to do with questioning whether the speed of light really is the limit for signal transmission. And we all know that as anyone who's taken basic physics, that is special relativity, that it's an absolutely well established fact that locally,"
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"text": " The speed of light is the limit for signal transmission, obviously going back to Einstein and a gazillion experiments since. But there are some unusual contexts that theories like string theory suggest. And those contexts suggest that the overall shape of space might be non-trivial in the sense that it might not just sort of go on forever. Space might curve back on itself and"
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"text": " You can ask yourself, what if the universe is in the shape of a loop, or at least are dimensions that are looped? That is, you go out in one direction, you go far enough, you'll come back to your starting point. And so we began to study signal transmission in universes where the signal could go all the way around the universe and route to its destination. And we found in certain circumstances that I'd be happy to elaborate that you could have signals"
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"text": " going in that unusual trajectory that would get to their destination faster than the signal that would seemingly be the quicker one moving right through the space time without traversing these closed curves. And so we found that there are signals that can go from here to there faster than the speed of light. This is related to the topology of the universe and not the variable speed of light? Yeah, this is not a variable speed of light."
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"text": " type of contribution as you know as you're making reference to there's been a whole industry that various physicists pursued over the course of many years wondering about whether the speed of light might vary through time a temporal dependence to the speed of light very interesting idea i really don't know that there's much evidence for it nor is there much evidence for what i'm talking about either so this is like throwing stones in a glass house but be that as it may"
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"text": " You're right. It all has to do with the topology of space. And if that topology is non-trivial, if there are non-contractable loops in that space, then that allows for qualitatively different trajectories for signals. And when you take those into account, you find that the signals can have a net speed that's faster than the speed of light. And moreover, it starts to sound a little bit kooky, but"
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"text": " When you take special relativity, you learn that if signal can go faster than the speed of light, then there are observers according to whom that signal may arrive at its destination prior to the time at which it was emitted. And indeed, we find examples of that. In other words, we find examples where you can send a signal into the past."
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"text": " And again, I hesitate saying this, but you asked me the question, what I've been working on lately, so I feel I need to answer fully and truthfully. I hesitate to say this because this has sort of been the playground of kind of"
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"text": " A closed timeline curve doesn't go against general relativity. Gödel had a solution"
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"text": " Are you suggesting some amendment to general relativity or are you just saying the actual structure of space-time or the shape of it is different so you're not proposing new laws? No laws. The whole notion of closed timelike curves is a tricky one. That's one where there's a full trajectory that gets back to its starting point prior to when it departed."
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"text": " exactly find those kind of structures in these theories. So if I send a signal out into space and send it somehow into the past, and then someone in the past gets that signal and fires back toward me, the return signal will always get to me in at least no time. In other words, it won't be that I get the signal prior to the moment when I emitted it. So"
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"text": " This would allow for interesting things such as, you know, we've always worried. Well, worried is probably too strong a word. We've always noted that if we discover intelligent life out there in the cosmos and it's very far away, how are we going to have a conversation, right? We send out a signal. Hey, how you guys doing? And what do we do? We wait like a hundred thousand years or a million years for the return signal. And by that point, we've forgotten that we were in a conversation at all."
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"text": " But in the theories that I'm describing now with these universes, with these non-trivial topologies, you can send a signal out into space and the person can get it and respond and you will receive it in virtually no time, in as little time as one can imagine. And so you can have a real time conversation with someone who's in an arbitrary distance. So I think that's pretty startling and mind boggling and kind of wonderful."
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"text": " And who knows if any of these ideas happen to be true, it would allow for conversations that in the more usual setting would just be impossible. But no, it's no amendment to general relativity. It's no change at all to the fundamental laws. That's the kind of fun thing about this approach. You know, if you come along and say, well, let's now bend the laws of physics as we knew it in the past, change it in some way. Sure, obviously, you're going to get some new effects, but then it all"
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"text": " depends on, the utility of it depends on, was that amendment, was that change at all reasonable? So we're not changing the laws of physics at all, we're just considering shapes of space that are very natural in certain unified theories like string theory, you know, Kaluza-Klein type theories that people studied in the past, and just examining conventional physics in a new setting."
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"text": " As opposed to new physics in either conventional or new setting. Is any of this related to wormholes or is this separate? It is definitely separate from wormholes in the conventional way that people think about wormholes, but there is a deep association in the following sense. If you"
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"text": " are looking at a signal that's traversing say you know a circular dimension of space. One of the most profitable ways scientifically of studying that is to imagine cutting that circle and opening it up into a line say an infinite line and then just having global identifications."
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"text": " point zero identified with two pi r, identified with four pi i, with six pi r and so forth. And in that way you effectively have a circle because of those identifications but you've unraveled it into a more conventional shape, a line. And then when a signal goes from zero say to two pi r, what's really in some sense happening is the signal is then in essence jumping through a wormhole and going back to its starting point."
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"text": " And so you can reframe everything that I'm talking about using the language of wormholes, but wormholes are not as essential to the story as it might be in certain other applications where you start to worry about things like, well, is the wormhole traversable? Will it stay open long enough for someone to actually go through or for a signal to go through? In this case, a wormhole is really more of a technique, a mathematical technique for analyzing"
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"text": " the situation as opposed to being fundamental to the whole idea. So this year, your plans are what? To work on this theory some more or? Yeah, we're going to definitely pursue, you know, look. And what is this called, by the way? Sorry, is there a name for this? Or a paper that people can look up? Yeah, we've written a couple of papers on it. The most recent one has the title Back to the Future, which"
},
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"start_time": 835.981,
"text": " The editors at Physical Review D initially sent the paper back and said we like the paper but you got to change the title because it's like we just don't have titles like that and I have to say I kind of took a little bit offence is too strong a word but you know we wrote back to them and said sure there's a cultural reference it's kind of fun but it's not just a cultural reference for a cultural references sake we truly are talking about"
},
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"text": " a signal that can travel from us back to the past and then into the future because as I said before the return signal always gets to us in a non-negative amount of time so it's it's back to the future it's like a perfect description of what we're talking about and to their credit"
},
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"text": " the editors at Physical Review D finally said, yeah, okay, you're right, it works. So the paper was accepted with that somewhat perhaps loose sounding title, but one that really does have a descriptive approach to what we're talking about that's spot on. And so yeah, if people want to see the technical details, that would be a paper to look at."
},
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"text": " And you have an event coming up at least here in Toronto on January 26th, if I'm not mistaken. So that's about a week from now when this is being published, when you're seeing this. Can you tell myself a little bit about that in the audience as well? Yeah, absolutely. So it's a talk at Roy Thompson Hall. I've never been there before, but at least the pictures look like it's a quite beautiful venue. And it's a journey that I'm going to take the audience on from"
},
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"end_time": 967.278,
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"start_time": 942.381,
"text": " the beginning of time up to the present and out toward the farthest that science can take us toward the end toward eternity. And my point in taking the audience on this journey will be partly to illuminate some of the key scientific ideas that guide the cosmological unfolding on the largest of scales and the largest of time scales."
},
{
"end_time": 992.398,
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"text": " But I also want to give people a sense of what science says about how we fit in to this cosmic order from this broadest, this largest perspective. And so we will be covering the formation of stars and galaxies, a little discussion about how entropy and life interplay and play off of one another and then"
},
{
"end_time": 1018.541,
"index": 40,
"start_time": 992.91,
"text": " Once we get to the present, we'll turn our attention toward the future and see how it all comes crashing down when you look at sufficiently large time scales as entropy gains the upper hand. And I'll conclude the evening with some remarks on how one might interpret this large scale understanding of the cosmos in more human terms."
},
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"start_time": 1018.865,
"text": " and how it is that perhaps this perspective can shed light on the age-old questions of meaning and purpose, which occupy all of us in one way or another. So how does it shed light on those, on meaning and purpose? Well, objectively. Well, you should come to the evening, but I'm more than happy to discuss it now in broad strokes."
},
{
"end_time": 1073.012,
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"start_time": 1044.411,
"text": " Look, you said objectively and I would say I don't know that objectively there is an answer. I think it is ultimately the subject of search that each human being is ultimately on to try to make sense of their life, make sense of their existence. But what this perspective does for me, and I found that it resonates with many people, it shows us how unbelievably astoundingly unlikely our own existence is."
},
{
"end_time": 1102.944,
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"start_time": 1074.172,
"text": " against the spectrum of possible combinations of base pairs of DNA, against the spectrum of possible molecular configurations, against the spectrum of possible outcome of quantum processes that stretch from the beginning until today, that each of them could have turned out one way versus the way they did, yielding a universe in which we wouldn't be here, against these astounding odds we're here."
},
{
"end_time": 1131.681,
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"start_time": 1103.695,
"text": " And to me, that's the beginning of the most fruitful, compelling and satisfying approach to finding some sense of purpose or meaning. Because rather than looking out to the universe, which we see in many philosophies and frankly, many religions, looking out to the cosmos to bestow upon us some ultimate answer, some ultimate meaning, some ultimate purpose,"
},
{
"end_time": 1157.073,
"index": 45,
"start_time": 1132.381,
"text": " This understanding of the cosmological timeline and the astounding unlikeliness of our own existence turns the spotlight inward. It turns the spotlight to a recognition of how astounding it is not only that we exist, but we have the powers that our particulate arrangement endows us with. Look what we can do. We can have this conversation."
},
{
"end_time": 1187.227,
"index": 46,
"start_time": 1157.654,
"text": " We can"
},
{
"end_time": 1215.06,
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"start_time": 1188.063,
"text": " To me, that is where a deep kind of gratitude emerges. And that gratitude is for the mere existence of human beings. And it's not dependent upon whether we're going to have some lasting legacy. It rather is just focused on the fact that we're here at all and that we can do the things that we can do. And with that comes an appreciation, which"
},
{
"end_time": 1244.326,
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"start_time": 1215.52,
"text": " For me is deeply compelling and satisfying, regardless of my understanding of how evanescent it all is. Do you fear death? I do. And I think that the fear of death is one of the major driving forces of the human species, both as a species as a whole and as individuals. And this is not an original thought."
},
{
"end_time": 1274.974,
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"start_time": 1245.162,
"text": " When I was, I guess, way back in college, I encountered a book called The Denial of Death by Ernest Becker, who himself was channeling and developing ideas of Otto Ronck, one of the great early psychologists who was in the Freudian school to begin with, and then really plowed his own path. And this idea that we humans are"
},
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"end_time": 1304.94,
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"text": " A rare life form that not only can we imagine the future, as I mentioned before, but we recognize that if we look far enough into that future, we're not there. We recognize that we are mortal. And that recognition of mortality fights against the urge for influence, legacy, a lasting part of us"
},
{
"end_time": 1329.616,
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"start_time": 1305.418,
"text": " We urge that we don't get washed away by the relentless winds of time, and yet that is not the way the universe is constructed. And so the fear of everything we love, everything we care about, everything we develop, everything that we worry about and spend energy and time on, that it all goes away,"
},
{
"end_time": 1359.155,
"index": 52,
"start_time": 1330.196,
"text": " To me is one of the deep insights and the deep motivators for how we humans behave. Have you ever inhabited a dark state of mind for a prolonged period of time? So, for instance, contemplation of suicide or ideation on the supposed objective meaninglessness of the world and that you have to find it subjectively, but maybe it was fringed to your sanity? Yeah, well, I would say that I've never gotten, thankfully,"
},
{
"end_time": 1389.036,
"index": 53,
"start_time": 1359.497,
"text": " to the place of sort of suicidal ideation and again you know anybody who has uh you know seek out help and guidance because there there are ways to get to a better place but i have certainly inhabited dark places and some of it has come from the things that we're talking about when you think about the cosmos and the laws of physics and our little tiny planet earth just"
},
{
"end_time": 1409.428,
"index": 54,
"start_time": 1389.531,
"text": " floating in this vast, perhaps infinitely vast darkness, there is a way that if you take that in emotionally as opposed to just purely intellectually, it can take you to a place of darkness and fear, foreboding. And I have explored that."
},
{
"end_time": 1439.923,
"index": 55,
"start_time": 1409.991,
"text": " So how have you gotten out of that? Well, one solution may be to separate the intellect and the emotion and just explore the vastness of the cosmos intellectually rather than emotionally because you may feel daunting. Or you could say, hey, look, maybe the fact that we're finite and temporally bound isn't what matters most because it's like going to a suffering child and saying, oh, that doesn't matter that the child's being tortured by some serial killer. It's finite."
},
{
"end_time": 1469.804,
"index": 56,
"start_time": 1440.35,
"text": " Without going into great detail, there certainly have been periods of my life, luckily they've not been incredibly long, but there have certainly been periods when I wasn't exactly sure how to find my way out of the dark space."
},
{
"end_time": 1499.753,
"index": 57,
"start_time": 1470.009,
"text": " Ultimately, what really helped me was, along the lines of what you're saying, to blend the human emotion, which can be terror of mortality, that can be a sense of insignificance against the cosmic order, but to blend that with a recognition that, sure, we may be insignificant, but we"
},
{
"end_time": 1504.019,
"index": 58,
"start_time": 1500.043,
"text": " As a species may have figured out how the universe."
},
{
"end_time": 1531.374,
"index": 59,
"start_time": 1504.241,
"text": " began and how it evolved and we may have figured out what laws of physics are in operation both here but also throughout the entirety of an infinite cosmos. We may have figured out laws that are relevant not just today and yesterday but perhaps relevant all the way 13.8 billion years ago and may continue to be relevant a hundred billion or a trillion or who knows how many years into the future."
},
{
"end_time": 1549.445,
"index": 60,
"start_time": 1531.459,
"text": " And so if you allow yourself to feel part of that human journey and that human achievement, I have found that that can assuage some of the darkness and make one feel a connection to a larger cosmos."
},
{
"end_time": 1576.237,
"index": 61,
"start_time": 1549.804,
"text": " And that connection to that larger cosmos for me has certainly helped to pull me from a place of smallness and feeling of darkness and insignificance to at least a connection that ameliorated those qualities and those feelings. Approximately how old were you when you were going through this period, if you don't mind me asking? You know, it's a good question, you know,"
},
{
"end_time": 1601.647,
"index": 62,
"start_time": 1576.681,
"text": " Certainly there was a time in my 40s that I can point to. There were episodes earlier, like right after college. I went through kind of a rough spell there, but it was thankfully relatively short-lived. And so it's been periodic, but it hasn't been debilitating."
},
{
"end_time": 1626.903,
"index": 63,
"start_time": 1602.329,
"text": " And when I look at the things that I've done that I value most, I can't help but think that those periods were pretty vital toward being able to do the things that I did. So life is a whole package, right? And that whole package, for some, will involve periods that are less comfortable than others from this perspective."
},
{
"end_time": 1655.708,
"index": 64,
"start_time": 1627.176,
"text": " Was it mainly the paltriness of existence or did you feel worthless as a result or for some other reason? And apologies if it's getting personal, but it's just that many people, including myself, like it's super helpful to see people that you look up to as a hero intellectually, especially going through what is common and emotional. Yeah, you know, it was definitely wasn't feelings of worthlessness. In a sense, it wasn't quite"
},
{
"end_time": 1685.64,
"index": 65,
"start_time": 1656.084,
"text": " that personal. I mean, obviously it was a very personal sensation and a personal challenge to overcome certain things that made it difficult to feel happy and to feel alive. But it was never a sense of, I, Brian Green, am worthless. It was more a sense of, oh my God, like, how does one live with the understanding"
},
{
"end_time": 1714.991,
"index": 66,
"start_time": 1686.186,
"text": " of the fact that apparently we are just the random output of random conditions being guided by a particular set of rigid mathematical rules. And if you think about that cognitively, it's kind of interesting and quirky. But if you think about it emotionally, it can really take you to a different place."
},
{
"end_time": 1742.432,
"index": 67,
"start_time": 1715.503,
"text": " And for me, as I was saying before, I think the key to going forward was to not be terrorized by those realizations, but find a way within those realizations to feel a deep gratification. And that's a place that I've been able to get to, but it's relatively recent getting to that place. It's not as though it's a"
},
{
"end_time": 1772.227,
"index": 68,
"start_time": 1742.875,
"text": " 19 year old or a 20 year old, this was something that was right there. And so it really is tying together the emotional and the cognitive into a narrative, a story that at least for me as an individual leads me feeling deeply connected to a wider reality and no longer feeling that sense of foreboding at the apparent"
},
{
"end_time": 1801.34,
"index": 69,
"start_time": 1773.592,
"text": " Is it possible to find meaning in disconnectedness? I often hear that connectedness is associated with meaning, but is it possible? Do you see a way that you could be too connected and you feel like, okay, let me just back off a bit. Well, it's a funny thing that you frame it that way because anybody who knows me personally would not consider me connected in the usual sense. I don't spend an enormous amount of time"
},
{
"end_time": 1830.009,
"index": 70,
"start_time": 1801.783,
"text": " with human beings outside of my most immediate family. My kids and wife like to joke of the lack of human contact that I have beyond a fairly small group. So I'm not talking about connection in that sense, although for some people that connection is utterly vital and utterly central to their being."
},
{
"end_time": 1860.179,
"index": 71,
"start_time": 1830.691,
"text": " I'm talking more of a kind of cosmic connection, a feeling of being integrated into a wider reality because we're made of the very same stuff as everything else in reality. We're guided by the very same laws as everything else in reality. We emerged by processes that stretch from the beginning until today as every other structure in the cosmos has as well."
},
{
"end_time": 1890.589,
"index": 72,
"start_time": 1860.862,
"text": " And so if you take that in fully enough and in the right light, it makes you feel part of the fabric of reality. And I think that's the connection that to me is the one that has proven to be the most important. Have psychedelics informed either your physics or your metaphysics? I can't really say. In fact, it's not completely clear to me whether or not I've actually ever had a psychedelic experience. No doubt you're referring"
},
{
"end_time": 1910.486,
"index": 73,
"start_time": 1891.049,
"text": " to the fact that in some more recent interviews I've opened up about certain experiences that at the time were absolutely terrifying. And in conversation with people who know far more about this arena than I do,"
},
{
"end_time": 1940.725,
"index": 74,
"start_time": 1910.998,
"text": " Their view is, you know, anything that takes your mind to a different place that ultimately you learn something from fits within the genre of exploration of altered states of consciousness. So framing it in that way, yeah, I would say that I have not had many such experiences, but the few that I have had, I guess gave me the deepest sense of how fragile"
},
{
"end_time": 1954.838,
"index": 75,
"start_time": 1941.135,
"text": " Ordinary cognition and ordinary experiences you introduce a few little molecules into the mind and these molecules radically change your experience."
},
{
"end_time": 1984.667,
"index": 76,
"start_time": 1955.333,
"text": " I mean, that's mind blowing, isn't it? I mean, you know, cognitively, we all know that what's happening inside of our head is just the cascading motion particles going through our brains, neurons firing, it's all describable at the level of particulate motion inside of our heads. Okay, good. I got that cognitively. Now let me just throw in a few more molecules. And all of a sudden, the experience changes radically. And so everything that that we"
},
{
"end_time": 2012.637,
"index": 77,
"start_time": 1985.111,
"text": " usually think of as defining reality, which is our experience in an intuitive level, can be not completely off kilter through some molecules. And that's a beautiful recognition. And it opens you up to the realization that our experience is not tapping into V reality. Our experience is taking a reality"
},
{
"end_time": 2041.459,
"index": 78,
"start_time": 2012.91,
"text": " and interpreting it and molding it and shaping it in a manner that our brains do because of how they form through evolution by natural selection across the eons. Our brains are the way they are because our forebears survived and they survived because their brains were in a particular configuration that allowed them to better navigate the environment than their competitors. And that brain interprets the world."
},
{
"end_time": 2070.23,
"index": 79,
"start_time": 2042.568,
"text": " We can change that interpretation by introducing new molecules and that is a deeply profound and eye-opening experience. If you could solve one problem, an academic one, so not let's take off the table world hunger or peace and so on, which one, and so this includes the hard problem of consciousness or philosophical problems as well as physics ones, which one do you most want solved by you?"
},
{
"end_time": 2093.387,
"index": 80,
"start_time": 2071.749,
"text": " Well, it's interesting and part of my answer will depend on what the answer is. So I think that the solution to the hard problem of consciousness, I suspect it's not going to be very interesting. I suspect that the solution to the hard problem of consciousness will be consciousness just is."
},
{
"end_time": 2119.667,
"index": 81,
"start_time": 2093.865,
"text": " It's a quality that emerges when matter takes on a particular organized form and undergoes certain very orderly and organized procedures and phenomena. And if that's the answer, and I think that is likely to be the answer, then count me out in terms of wanting to solve it. I think that may be the solution. If it's more interesting than that, if there's some consciousness field that"
},
{
"end_time": 2148.558,
"index": 82,
"start_time": 2119.923,
"text": " you know, various religions talk about or, or something that we can't even imagine. And that's the root of consciousness. Yes, then I'd love to be part of the journey to solve it that way. But assuming that it's the more boring, but nevertheless, you know, profoundly important solution on what the heart problem is, then the other questions that I would really love to be part of finding the solution of is, what is time?"
},
{
"end_time": 2168.097,
"index": 83,
"start_time": 2149.582,
"text": " Is it just a secondary feature of the world that we human beings find useful in order to organize our perceptions of the world? Or is time more fundamentally woven into the fabric of reality? Is there a realm of reality in which there's no conception of time?"
},
{
"end_time": 2196.749,
"index": 84,
"start_time": 2168.541,
"text": " because the conditions simply have not gelled to the point where a conception of time can even emerge, or is there always a notion of time because it's just fundamentally part of how reality is constructed? I'd say that would be the one big one. And then, allied with that, you know, look, I'd love to know what the unified theory is, right? I'd love to know what"
},
{
"end_time": 2226.032,
"index": 85,
"start_time": 2198.558,
"text": " A thousand years from now, kindergarteners are going to learn in their course on Unified Field Theory, if that's the answer, you know, what is it and where does it come from? We can have a final theory, whatever it is, general relativity plus quantum, or maybe it's radically different, but whatever that ultimate theory is, where did it come from? Did someone in some"
},
{
"end_time": 2252.466,
"index": 86,
"start_time": 2226.34,
"text": " super simulation dream it up and we are just living out or where in the world do these fundamental laws and regularities and patterns come from in essence really why is there something rather than nothing i mean can't really get deeper than that and by nothing i don't mean you know empty space i don't mean nothing in the sense of a void i mean truly nothing"
},
{
"end_time": 2278.439,
"index": 87,
"start_time": 2252.79,
"text": " Do you think that a true toe or a good toe is one that explains itself?"
},
{
"end_time": 2309.07,
"index": 88,
"start_time": 2279.667,
"text": " Whenever you talk about a theory of everything, and I will frame it that way, I never use the word toe myself, but whenever you talk about a theory of everything, you have to say to yourself, what is embraced by everything? Usually when we physicists throw away, throw around, not throw away, when we throw around the term theory of everything, we usually mean a very limited everything. We usually mean the particles and the laws."
},
{
"end_time": 2333.643,
"index": 89,
"start_time": 2309.394,
"text": " You know, the ingredients and the rules, that's what we mean by everything. But given that one can say, but why are there any particles? Why are there any rules? And so yeah, your way of framing it that if that theory of everything could somehow establish its own inevitability, if that theory of everything somehow has built within it,"
},
{
"end_time": 2354.804,
"index": 90,
"start_time": 2334.224,
"text": " That the lack of existence of that theory of everything would somehow be itself a logical inconsistency. So that reality could not have this theory of everything because reality is, we believe, in some sense, consistent. That would be deeply compelling."
},
{
"end_time": 2384.701,
"index": 91,
"start_time": 2356.408,
"text": " Dyson conjectured that the Gödel incompleteness theorem or one of them applied to physics and so we may never know a toe. I don't recall his argument but I'm sure you've heard an argument akin to this. Can you spell it out for the audience and then where do you stand on it? You know, I have to say I have struggled myself for a long time to really know or at least have a feel for the relevance of Gödel's ideas."
},
{
"end_time": 2406.732,
"index": 92,
"start_time": 2385.435,
"text": " when it comes to the laws of physics. And there was a time when I tried to convince myself that because Gödel's theorem itself relies upon assumptions, could we modify the assumptions in such a way that"
},
{
"end_time": 2434.002,
"index": 93,
"start_time": 2407.585,
"text": " the new assumptions could be relevant to the universe but the conclusion that girdle came to would no longer be relevant because the assumptions had changed and there are a handful of relatively straightforward ways to do that and frankly i don't even haven't thought about it in detail in quite some time but i i remember going through and say aha all we have to do is"
},
{
"end_time": 2455.213,
"index": 94,
"start_time": 2434.275,
"text": " Imagine a universe in which this is not true, and that universe could be our universe, like paracompact logic. I mean, there are ways in which you can go beyond the limited set of assumptions that Gödel had. And so I more or less have convinced myself"
},
{
"end_time": 2481.664,
"index": 95,
"start_time": 2455.64,
"text": " that Gödel's ideas need not imply that we will somehow fundamentally be in an undecidable situation when it comes to understanding the deep laws of the universe. It doesn't mean that Gödel's ideas might not apply. They could, but they don't have to. And with that realization, I became less interested"
},
{
"end_time": 2503.865,
"index": 96,
"start_time": 2482.142,
"text": " in and really puzzling because now we're in a realm that's so esoteric and abstract relative to the kind of concrete problems like what's the dark matter and what's the dark energy and you know is there just a unified theory of the particles of matter that we have discovered it just felt"
},
{
"end_time": 2528.063,
"index": 97,
"start_time": 2504.787,
"text": " 20 steps removed from those kind of deep but really hands-on questions that I haven't spent a whole lot of time thinking about since. Speaking of time, do you believe time to be, well maybe you don't, let's not say believe. When you were playing with some ideas earlier and you're saying well time may be emergent, do you also believe space to be emergent? Do you believe space time itself is emergent?"
},
{
"end_time": 2552.363,
"index": 98,
"start_time": 2529.206,
"text": " Yeah, I mean, if time is emergent, it's hard for me to imagine that space is not emergent, too. Again, anybody who's spent a little time thinking about the insights from Einstein on recognizes that space and time are so deeply and intricately interwoven into the fabric of space-time, that sort of"
},
{
"end_time": 2582.858,
"index": 99,
"start_time": 2553.183,
"text": " Pulling one apart and imagining it has different properties, space and time have different properties, it's not impossible, but it does fly in the face of pretty much everything we've learned in the last hundred years. So I certainly do envision that if there's a realm of reality in which time does not apply, because as we were saying before, the conditions haven't yet allowed for a conception of time to emerge, the same would almost certainly be true of space."
},
{
"end_time": 2608.797,
"index": 100,
"start_time": 2583.268,
"text": " So the real way of saying it is, is there a realm of reality in which there's no conception of space time? And it's hard for me to imagine what that is, but that's because I've got this brain that is constrained by what my ancestors did. And that brain is one that is so tied to a conception of reality."
},
{
"end_time": 2638.046,
"index": 101,
"start_time": 2609.224,
"text": " in which space and time are the architecture within which events take place, that it's really hard for us to think about a reality in which there isn't space-time. And so I wish I could give some really good example or insight into what that would be like, but it would be some kind of reality in which the language that we use would not talk about when things are happening,"
},
{
"end_time": 2666.988,
"index": 102,
"start_time": 2638.268,
"text": " And the language that we use would not talk about where things are happening. The language would somehow be beneath that, more fundamental than that. And it's not that scientists don't have some ideas for what this might be like, but I'd say that we do lack the deep picture and the deep story of how we would really articulate and navigate a reality absent space-time."
},
{
"end_time": 2695.759,
"index": 103,
"start_time": 2668.2,
"text": " Have you had a chance to go through Wolfram's theory, his project on physics? I wish I had. Steve's a great guy and he's a friend and we talk about things on occasion and I wish I had more time to spend with him because it's always illuminating when we do spend some time together. But I've not"
},
{
"end_time": 2723.319,
"index": 104,
"start_time": 2697.073,
"text": " I don't feel like I fully grasp the approach that he's taking. Why? I can absolutely throw this on myself. It could well be limitations in my own thinking and limitations in the amount of energy and effort that I've expended to understand his approach more fully."
},
{
"end_time": 2751.664,
"index": 105,
"start_time": 2723.66,
"text": " I get stuck on trying to really understand whether the formalism, as he envisions it, is it actually fundamentally different from the more traditional formalism? He would say, yes, as far as I can tell. But as I have looked at it on occasion, it has struck me that it's not obvious to me that it is as different as he suggests. And again, I could be wrong on this."
},
{
"end_time": 2771.186,
"index": 106,
"start_time": 2751.817,
"text": " And it could be that I just haven't put enough effort or energy into it. I'm glad that he's pursuing his approach. It's not within the confines of the traditional established environment is not doing it inside of the physics department or math department."
},
{
"end_time": 2801.374,
"index": 107,
"start_time": 2771.698,
"text": " You know, he has the resources and the creative energies to make his own environment and to find his own collaborators and more power to anybody who has the capacity to do that. Whether it's going to bear the fruit that he envisions, I don't know, but I'd say the same thing about what we're doing here. Like we've been beating down on string theory, you know, since"
},
{
"end_time": 2830.776,
"index": 108,
"start_time": 2801.493,
"text": " You know 1984 at least you know the the big first revolution but since 1968 if you want to go further back to the first glimmers of string theory and where are we now 2023 that's a lot of years right so you can say the same thing you know so so i don't feel qualified to really judge the approach but i i just feel that i haven't fully wrapped my head around whether or not it's"
},
{
"end_time": 2859.616,
"index": 109,
"start_time": 2831.254,
"text": " What progress has been made in string theory in the past two decades?"
},
{
"end_time": 2888.422,
"index": 110,
"start_time": 2859.94,
"text": " a connection between gravity and quantum mechanics that I don't think would be sufficiently appreciated 20, 25 years ago. I mean, take my book just as one moment in time, a snapshot in the elegant universe. I was published in 1999. And in that book, I very clearly lay out there's this theory called general relativity describing gravity, the big stuff,"
},
{
"end_time": 2918.729,
"index": 111,
"start_time": 2889.343,
"text": " I lay out how there is this other theory called quantum mechanics, describing the small stuff, and we want to put them all together, have a unified theory of the big and the small, but we're having trouble doing that. And then I go into the book and how string theory seems to be making progress in putting the big and the small together. If I was writing that book today, and in some sense I am, because I'm adding a chapter for the 25th anniversary of the elegant universe,"
},
{
"end_time": 2948.456,
"index": 112,
"start_time": 2919.275,
"text": " And one of the things that I'm emphasizing is there's now a lot of evidence that gravity and quantum mechanics in some sense are kind of the same theory. They are already in some strange sense combined. And this was completely unexpected based on anything that we knew 20 or so, 20 plus years ago."
},
{
"end_time": 2970.998,
"index": 113,
"start_time": 2948.865,
"text": " So within, for instance, general relativity, there are these structures you made reference to one of them earlier called wormholes, which are tunnels in the fabric of space going from one space-time location to another through a kind of shortcut. That's general relativity. In quantum mechanics, there's this weird thing called quantum entanglement."
},
{
"end_time": 2994.616,
"index": 114,
"start_time": 2971.288,
"text": " where two widely separated particles can act as though they're right next to each other, even though they can be on opposite ends of the universe. And really nobody thought there was a connection between these two ideas until people like Lenny Susskind and Juan Maldacena and a variety of other influential scientists, too many to name them all,"
},
{
"end_time": 3023.131,
"index": 115,
"start_time": 2995.538,
"text": " gave evidence that in some sense wormholes and entanglement are kind of the same thing. They kind of feel the same if you think about it. Wormhole, it's connecting one point in space time with another through a shortcut. Entanglement is connecting one particle in space time with another particle in some sense through a shortcut because they're acting as though they're right next to each other. And so this is the beginning, the tip of an iceberg of a deep and very powerful story."
},
{
"end_time": 3037.858,
"index": 116,
"start_time": 3023.473,
"text": " which is showing that structures in general relativity and structures in quantum mechanics are already deeply connected and deeply entwined. And so the unification program may ultimately not be described"
},
{
"end_time": 3065.708,
"index": 117,
"start_time": 3038.387,
"text": " in terms of putting gravity and quantum mechanics together, the way I described it, and many did, of course, in the earlier days. But it may be more deeply understanding general relativity, more deeply understanding quantum mechanics, and more deeply understanding how they are part and parcel of the same theoretical structure. So the recent results by Google of the ER equals EPR, is that overhyped? Is that underhyped?"
},
{
"end_time": 3096.067,
"index": 118,
"start_time": 3066.237,
"text": " I also can you explain the results to the audience? Yeah, so this is a little bit controversial. There have been some feathers ruffled by some recent activity. And what the idea is that if, for instance, what I said a moment ago is true, that there's this deep connection between wormholes and general relativity and entanglement in quantum physics,"
},
{
"end_time": 3122.227,
"index": 119,
"start_time": 3096.493,
"text": " Then a number of influential physicists pointed out that by doing certain calculations on a quantum computer, you would in some sense be simulating a wormhole in general relativity, because quantum computing is all about leveraging quantum entanglement between qubits. And so"
},
{
"end_time": 3152.398,
"index": 120,
"start_time": 3122.858,
"text": " There was a recent paper and it was making use of the quantum computational capacities at Google and I think the kerfuffle is more about language than anything else because some of the folks who were carrying out this work, this is like Maria Sparoppolu and Joe Licken and Daniel Jefferson and so on, there was at least some"
},
{
"end_time": 3173.046,
"index": 121,
"start_time": 3152.619,
"text": " Part of the"
},
{
"end_time": 3200.026,
"index": 122,
"start_time": 3173.524,
"text": " they were modeling a wormhole or kind of simulating a wormhole as opposed to actually creating a wormhole. You know, one comment I saw by the, the really deeply insightful quantum computational physicist, Scott Aronson was saying to say that you created a wormhole in, in undertaking this quantum computer simulation,"
},
{
"end_time": 3217.927,
"index": 123,
"start_time": 3200.503,
"text": " We'd be tantamount to saying that every time you drew a wormhole on a piece of paper, you created a wormhole. It's like, how do you distinguish between modeling something and the something? And I think that distinction, perhaps according to some, was lost in some of the"
},
{
"end_time": 3246.817,
"index": 124,
"start_time": 3218.609,
"text": " ways in which the results were articulated. But putting the controversy or the bit of kerfuffle to the side, it's a very, very interesting piece of work in which doing a quantum computation and appropriately interpreting it, you could see within that computation the kinds of phenomenon that you would associate with a wormhole."
},
{
"end_time": 3276.817,
"index": 125,
"start_time": 3247.961,
"text": " And that's a beautiful thing because it now is a very concrete realization of what I was saying before in answer to your question of what's new in the last 20 years. What's new is here you're doing something that's purely quantum mechanical. You're carrying out a quantum computation on a quantum computer. And then by analyzing it appropriately, you're saying, oh my God, look in there. We're seeing exactly what we'd expect in a particular kind of wormhole."
},
{
"end_time": 3306.596,
"index": 126,
"start_time": 3277.517,
"text": " And so the connection between general relativity and quantum mechanics becomes that much more apparent. The uncontroversial statement is that they've simulated a wormhole or modeled a wormhole. I don't want to speak at a turn because I don't want to speak for either side of this debate. But I would say that I think that's the linchpin of some of the controversy. And so it feels less important to me"
},
{
"end_time": 3334.718,
"index": 127,
"start_time": 3307.108,
"text": " When thought of in that light, I'm just interested in how curious and wonderful it is that general relativity and quantum mechanics are rushing up against each other in a manner that we really wouldn't have anticipated with the level of our understanding 20-25 years ago. Okay, now speaking about what's overhyped or potentially underhyped, what are some of the applications of category theory to high energy physics?"
},
{
"end_time": 3357.039,
"index": 128,
"start_time": 3336.92,
"text": " Oh goodness gracious, wrong person to talk about. You know, I've read some of the papers on this stuff, but I don't feel sufficiently expert to weigh in on that at all. So, sorry. All right, no problem. So, there are different toes like Garrett Leesey's, like Eric Weinstein's, and Peter Wojt, and I'm curious"
},
{
"end_time": 3387.483,
"index": 129,
"start_time": 3357.773,
"text": " Have you had a chance to look into any of those, like Lisey's E8 or Eric Weinstein's Geometric Unity or Peter White's Euclidean Twister? I didn't even know that Peter White had put forward a particular idea, so again, I'll have to claim ignorance on that front. But the Garrett-Lisey stuff, unless there's something radically new in recent years, certainly when he first gained a little bit of attention for the ideas he was putting forward,"
},
{
"end_time": 3404.258,
"index": 130,
"start_time": 3388.046,
"text": " I have to say I relied upon a good friend who I've known for 40 years, perhaps Jacques Dissler at the University of Texas who did a wonderful series of blog posts"
},
{
"end_time": 3434.599,
"index": 131,
"start_time": 3404.616,
"text": " that"
},
{
"end_time": 3463.899,
"index": 132,
"start_time": 3435.009,
"text": " Again, in any detail, so I can't comment. But I guess, you know, I've not I've not encountered anything beyond quantum gravity, which I don't work on. I don't I don't study. But I certainly respect the results that that community has put forward. And, you know, while some people take exception with certain things that Lee Smolin, one of the leaders of that field has"
},
{
"end_time": 3475.742,
"index": 133,
"start_time": 3464.445,
"text": " said about string theory. I sort of don't take those things personally and I focus more on the ideas and I think they've done some some wonderful work."
},
{
"end_time": 3494.906,
"index": 134,
"start_time": 3476.254,
"text": " in understanding connections between general activity and quantum mechanics. But one would say that I'm biased. I don't see anything that's achieved the level of refinement and sophistication and insight that string theory has provided."
},
{
"end_time": 3524.735,
"index": 135,
"start_time": 3495.538,
"text": " Nothing that I've seen remotely holds a candle to the kinds of insights, especially the ones that we were just talking about a moment ago, which are both deep and surprising. But even before that, the capacity to have a theory that is quantum mechanical and has general relativity embedded and is able to have within it the symmetries"
},
{
"end_time": 3552.858,
"index": 136,
"start_time": 3525.162,
"text": " the standard model of particle physics and the particles in the standard model and naturally is within their theory that's able to give us insight into things like the entropy of black holes which again you know loop quantum gravity has its own insights but I think the string theoretic ones are deeply impressive and so there have been so many small achievements"
},
{
"end_time": 3581.63,
"index": 137,
"start_time": 3553.285,
"text": " along the way. Yeah, we haven't gotten the big one, which would be an experiment that somehow reveals that this approach to nature is the right approach. But there have been so many achievements over the course of the last 50 years that I haven't felt compelled to look for another approach because we've got a rich, wondrous, deep, compelling theory that we're in the midst of unraveling."
},
{
"end_time": 3605.316,
"index": 138,
"start_time": 3582.278,
"text": " And so that feels to me a very strong pull relative to, you know, somebody comes up with some idea, raises their hand and said, now look at what I've got. And that to me, I'm glad there are people who are doing it, but it's typically not the thing will grab my attention away from the focus work that I'm doing and that we're doing as a community."
},
{
"end_time": 3634.36,
"index": 139,
"start_time": 3605.879,
"text": " What would be the other people in the ring that you see as competent boxers that are opponents to string theory? Or perhaps it's not a competition. They're all claring for the same. They're all fighting toward the same goal. So what else is there? So there's loop. But again, that's not a toe per se. It's quantum gravity approach, unless there's some other development I'm unaware of. Do you mind listing some? No, I wouldn't. I guess first of all, like I said before, I typically don't use the language."
},
{
"end_time": 3661.067,
"index": 140,
"start_time": 3635.111,
"text": " It's not because of the abbreviation of the acronym. I think that the whole conception of everything is an odd one. So when you talk about loop quantum gravity, you know, if you have a theory that is able to embrace general relativity and quantum mechanics in some calculable and coherent mathematical form,"
},
{
"end_time": 3687.841,
"index": 141,
"start_time": 3661.817,
"text": " That's huge, right? I wouldn't say that it somehow is subordinate to string theory because within string theory, you know, perhaps you can also put the standard model particle physics most direct, you know, if loop quantum gravity works, you will be able to use it as an overarching framework and then put in quote unquote, everything else put in matter, I have no doubt that that this is a"
},
{
"end_time": 3716.34,
"index": 142,
"start_time": 3688.097,
"text": " a potential future if indeed loop quantum gravity is the right way to go. So I wouldn't somehow diminish it and say, well, string theory is a theory of everything and loop quantum gravity is not. I don't think that way at all. I mean, to me, the big question is, you know, what do we do about general relativity and quantum mechanics? And what's becoming clear, as I mentioned before, is that the idea of trying to meld them together may itself have been somewhat wrongheaded."
},
{
"end_time": 3742.892,
"index": 143,
"start_time": 3716.715,
"text": " that may already be melded together and it's up to us to understand how that melding actually works. I mean, as you know well, once quantum mechanics came on the scene in the 1920s, there was this approach developed called quantization, where you took ideas from the pre-quantum world, classical physics, and you found a kind of algorithm"
},
{
"end_time": 3763.66,
"index": 144,
"start_time": 3744.121,
"text": " For making them quantum mechanical, that algorithm was called quantization. Take Newton's ideas, make them quantum mechanical. And that was the rhythm. That was the approach that we took for a long time. That may not be the right approach. It may not be you take Einstein's ideas of general relativity and you quantize them."
},
{
"end_time": 3792.073,
"index": 145,
"start_time": 3764.07,
"text": " They may already have quantum mechanics within them. And that that's the deep, new and exciting insight. So he asked me sort of what are the sort of competitors or candidates? You know, well, certainly I consider, as I mentioned before, the loop quantum gravity community. Many colleagues, many friends in that world, and I respect what they are doing."
},
{
"end_time": 3818.933,
"index": 146,
"start_time": 3792.927,
"text": " I think as I mentioned that the string theoretic approach has achieved more and it feels like it's giving us more surprising and detailed insights but no doubt people would say partly your view is colored by the fact that you know since I was a graduate student that's been more or less the domain within which I've walked. None of the other ideas that I've"
},
{
"end_time": 3847.637,
"index": 147,
"start_time": 3819.616,
"text": " scene described and again I full well say I do not investigate them all because I don't have the time but I've not seen anything else that rises to that level of achievement or sophistication. The reason behind my question is that I'm working on a paper with a colleague Carlos Zapata where we're going to do an inventory of the candidates for unification attempts between gravity and quantum mechanics so maybe you don't want to call it toes, whatever."
},
{
"end_time": 3874.258,
"index": 148,
"start_time": 3848.302,
"text": " Let's just call it a toast for the sake of this. And then also some desiderata on the side, like does it explain so and so on? And there's some uncontroversial list on Wikipedia of the outstanding problems in physics and putting a checkmark like a matrix with one on the X axis, one on the Y axis. And so I wanted to know, well, I'm asking different physicists and also mathematicians who work in physics, what are the different candidates that should go there?"
},
{
"end_time": 3901.049,
"index": 149,
"start_time": 3874.718,
"text": " And I know that you mentioned that there are several people who raise their hand as difficulty can't follow every single one who says I have a toe. The toe by Lisey and and Weinstein and Eric Wolfram. They're of a different quality than the average person who emails and says that they have a toe. That is in mathematical sophistication, maybe not rigor. But hey, the elements of a toe, even quantum field theory is not entirely rigorous. But the point is in terms of mathematical sophistication, they're in a different league."
},
{
"end_time": 3931.357,
"index": 150,
"start_time": 3901.544,
"text": " So I'm curious what else goes there. And then I wanted to do a waiting, like, it's a bit unfair to say, so 32 solves seven out of the 15. But Wolfram's only solves five out of the 15. However, Wolfram's working on it in a basement, maybe a basement in a lovely house, but like an abasement. And, and there's, let's say 1000 people working on SL 32 across decades or a heterotic eight or whatever it may be. So then I was like, how do I do that waiting? And then, but anyway, so it's a fun project."
},
{
"end_time": 3959.565,
"index": 151,
"start_time": 3931.971,
"text": " And I just wanted some help with it and I wanted to hear what your thoughts were and what else you think I should consider putting in it or not putting in it. Look, I mean, it sounds like fun and I'm sure I enjoy reading it when it comes out. But the interesting thing is to most researchers in the field, the work is all about the details."
},
{
"end_time": 3989.804,
"index": 152,
"start_time": 3960.162,
"text": " And you're right that we all receive these letters in the mail and sometimes they're actually kind of heartbreaking. I've gotten letters from people who've been in that basement that you just made reference to, not a particularly nice one, I would imagine, working out the final theory of everything. I remember one gentleman wrote to me and I think he was on the level. He was saying how he's been working on this for 20, 25 years."
},
{
"end_time": 4013.37,
"index": 153,
"start_time": 3990.316,
"text": " His wife left him, his kids left him because the only thing he cared about was working out this theory and he finally had the theory and it sent it to me. And it looked like every other theory that I get through that particular idiom. All sorts of graphs and lines and interconnected shapes and you're like, oh my God, you know,"
},
{
"end_time": 4043.387,
"index": 154,
"start_time": 4013.729,
"text": " This is probably insane. I mean, not insane in some medically verifiable sense, but it's deeply sad that someone who has the same urge that we have, right, wants to figure it all out, is somehow likely being misled by certain kinds of patterns or certain kinds of geometrical shapes that really have no bearing on the final answer. And the number of times you get"
},
{
"end_time": 4073.387,
"index": 155,
"start_time": 4043.985,
"text": " communications of the sort where it's all about working out ratios of like pi to the ninth divided by e to the seventh you know time you know and and and they work out to like 12 or 15 decimal places and they find some pattern in the numbers and yeah it hurts inside to imagine someone spending their life doing something like that which is meaningless and so yes that category of work is quite different"
},
{
"end_time": 4101.237,
"index": 156,
"start_time": 4074.258,
"text": " from any of the other ideas that you've put forward. But in the end of the day, people vote with what they work on. And string theory has attracted a great deal of people to work on it. And by string theory, I mean now something broader than what I would have meant, say, in 1990 or 2000. String theory now is"
},
{
"end_time": 4127.363,
"index": 157,
"start_time": 4101.442,
"text": " any work that uses the ingredients or the insights or the mathematical formalism that was part of the early development of string theory. So now, you know, people who are working on connections between gravity, general relativity and quantum mechanics and tangleman as we described before, would I call that string theory per se? I don't know. It would have been"
},
{
"end_time": 4156.869,
"index": 158,
"start_time": 4127.619,
"text": " very unfamiliar to a string theorist, say from 1980, but that's what progress is. It's wherever the ideas lead you. So as a community, it's hard for me to compare anything to the string theory community for the level of insight and the level of achievement. So sure, I mean, it's nice to lay out like in a matrix in a chart, you know, the various approaches that that serious"
},
{
"end_time": 4185.657,
"index": 159,
"start_time": 4157.073,
"text": " scientists as opposed to perhaps untrained folks in basements what serious scientists have been focused their attention on but I really don't think anything comes close to what the string theory community broadly defined has achieved and again I do have great respect as I mentioned for the loop quantum gravity community but none of the others for me really are developed to a point that are worthy"
},
{
"end_time": 4214.77,
"index": 160,
"start_time": 4185.964,
"text": " of exploration and attention, at least not yet. What advice do you have for people who are interested in physics, like seriously interested in physics, but aren't able to go to university for whatever reason? Maybe they're older now and they feel like they don't want to go back, they have not enough time, or they just don't have the money or whatever life circumstance. Yeah, well, look, you know, I never want to discourage people. There may be a Ramanujan in our midst."
},
{
"end_time": 4244.889,
"index": 161,
"start_time": 4215.179,
"text": " You know, someone whose level of perspicacity is so off-scale that they don't need the traditional training and they don't need the traditional environment and then they can produce things that, you know, I forget exactly the quote, but mathematician G. H. Hardy, when looking at some of the theorems that Ramanujan had sent him, said something like, you know, if these are true, he's the greatest mathematician."
},
{
"end_time": 4275.026,
"index": 162,
"start_time": 4245.35,
"text": " If these are not true, he's an even greater mathematician for having thought them up when they're not actually true. I mean, you know, so if there's somebody like that, wow, more power to them and they can pursue these kinds of ideas on their own or maybe through brief communications. But for the vast majority of people of the sort that you're describing, it is really tough to do this outside of a community of coworkers."
},
{
"end_time": 4305.077,
"index": 163,
"start_time": 4275.469,
"text": " I mean, the way we physicists typically work, you know, in my office at Columbia, students and grad students and postdocs and seminars and informal conversations. And you read this paper and you hear that idea, you talk to that person, you start to develop this collaboration, that collaboration. It's just really hard to do physics without that. And so if one is not in that world and one is somewhat older, it's really tough to break in."
},
{
"end_time": 4334.94,
"index": 164,
"start_time": 4305.725,
"text": " And for most people, they don't have the financial resources to just give up their life and go back to school, especially with the fact that, I mean, you know, maybe things are changing, but, you know, it's tough to get a faculty job if you get your PhD at like 70. It's just unlikely. I'm using extreme numbers to avoid anybody like jumping down on my throat and some ageism, you know, but you know what I'm saying? The typical route,"
},
{
"end_time": 4362.927,
"index": 165,
"start_time": 4335.282,
"text": " The typical route is someone gets their PhD at a relatively young and society views it as more energetic, fertile age, and then they get a faculty job and they're often running as part of the community. And when you, when you delay that, it's really, really hard. I mean, I have known, and you know, individuals who loved, I remember I'm thinking of one guy in particular loved mathematics."
},
{
"end_time": 4392.79,
"index": 166,
"start_time": 4363.387,
"text": " And he went back and got his PhD at a relatively advanced age, which wasn't old, but relatively advanced age compared to the norm, and got himself a really nice teaching job at a university. And as far as I can tell, I haven't spoken to him. I was quite happy because he's spending time in the community of ideas that he finds most exciting. But it's tough. That's rare. That's really tough."
},
{
"end_time": 4420.691,
"index": 167,
"start_time": 4393.029,
"text": " So, you know, I guess the advice would be maybe you can find enough gratification from reading about the ideas and maybe going to a local university when they have a seminar series. Maybe you can, you know, and maybe through that you can find inroads into your local community at a local university and maybe even begin some collaboration on some kind of project. But it's not an easy path."
},
{
"end_time": 4450.64,
"index": 168,
"start_time": 4420.93,
"text": " and certainly not if one wants to make it their sort of career and for them to make a living from it. That's really tough if you're not in a traditional trajectory. What an analogy be if someone wants to learn martial arts? Sure, you could do so on your own. You can watch YouTube videos, but there is something about grappling with other people using your body with someone who is living rather than a wooden machine. There's something about the group dynamic or does that analogy fail?"
},
{
"end_time": 4480.913,
"index": 169,
"start_time": 4451.22,
"text": " You know, I think it's a really good analogy, and I think I may use it going forward. So thank you on that one. But because, look, the number of times, you know, I'm reasonably well-accomplished, right? The number of times when I've been working on something, I'm completely stuck. I try this, I try that, it's just not happening, right? Then I'll meet with a few people, you know, here at Columbia, we do chit-chat, talk, oh, boom, now we know where to go. Where did the idea come from?"
},
{
"end_time": 4510.06,
"index": 170,
"start_time": 4481.647,
"text": " None of us had the idea of going in to that exchange, but yet somehow in the midst of that grappling, if I go back to your metaphor, the potential idea emerged. And so without that, it's very hard to make progress. Have you ever collaborated with Ed Whitten? Collaborated, no, but worked"
},
{
"end_time": 4540.179,
"index": 171,
"start_time": 4510.435,
"text": " Right next to him, yes, in the sense of back in the 1990s, I was at the Institute for Advanced Study and we had an idea. I had a particular idea of something I wanted to prove that the fabric of space could rip and Ed is at the Institute for Advanced Study. I told him about this idea, thought it was exciting. I was working with a couple other people, Paul Asimov, Dave Morrison."
},
{
"end_time": 4569.172,
"index": 172,
"start_time": 4540.538,
"text": " Edward started to work on his own version. Didn't take anything from us. He just went a completely different direction, but yet converged on exactly the same question. And it was among the most exciting times that I've had in physics because like we knew he was closing in on it. We were closing in on it. We knew that he's a million times smarter than we are. So we had to work a million times harder and faster to try to get there and not be completely scooped."
},
{
"end_time": 4595.299,
"index": 173,
"start_time": 4569.497,
"text": " And basically at the same time, late in the fall, I guess, of 1992, it was, within days came to the same conclusion from completely different approaches. And so we were right, right there, you know, head to head. It was an incredibly exciting time. But yeah, he's again, you know, one of those figures whose intellect is just hard to fathom."
},
{
"end_time": 4616.63,
"index": 174,
"start_time": 4595.879,
"text": " I was speaking to Richard Borchards and he said, Ed Whitten is terrifying. And I said, well, why? And he said that he puts out as side effects whole other fields like the Whitten invariance, like sideburns. You have to tell you, it's funny, a friend of mine was at the Institute for Revenge study over a summer."
},
{
"end_time": 4630.708,
"index": 175,
"start_time": 4616.988,
"text": " And the place that kind of cleared out and I think Edward was there and this friend of mine was there. I won't give his name in case he wouldn't want me to share it, but they were kind of sharing a wall. Their offices were right next to each other."
},
{
"end_time": 4658.524,
"index": 176,
"start_time": 4631.049,
"text": " And so my friend was slogging away doing his calculations, you know, hitting dead ends. And all through the summer, he kept hearing tap, tap, tap, tap, tap, tap as Ed was typing out paper after paper after paper as if he was just sort of sitting there. And the ideas were sufficiently formed that he didn't even have to write anything out. He could go right from brain to finished paper. And my friend was like, you sit there and you're like, what am I doing? Why am I in this field?"
},
{
"end_time": 4686.544,
"index": 177,
"start_time": 4659.206,
"text": " You know, I can't, I can't, but that's actually an important thing. There is a place where so many people can contribute, sort of back to the question we had before. While it's harder for the person who's not gone to graduate school or is working in the basement to really make that contribution, kids who go to undergraduate then go to graduate, there's so many ways for so many different people with so many different"
},
{
"end_time": 4715.896,
"index": 178,
"start_time": 4687.585,
"text": " levels of intellectual capacity and level of insight to contribute and to contribute in vital ways. And so you don't have to only be an Edward Witten in order that you advance the field. And so it's absolutely the case. How do you not feel demoralized if you're working on the same problem as Ed Witten or synonym for Ed Witten? So you work on a different problem or what? Or you try to collaborate? Look, I mean,"
},
{
"end_time": 4742.91,
"index": 179,
"start_time": 4716.954,
"text": " So I gave you one example where we were working on the same problem in a sense as Edward Witten and the fact that we got to the finish line at the same time is again one of those great achievements that I will always remember. For Edward, it was just another day at the office. But having said that, I think it's very important that you pick your problems carefully."
},
{
"end_time": 4770.026,
"index": 180,
"start_time": 4744.087,
"text": " You don't want to take, I don't like to take a problem that every other physicist deems as the most important and they're all working on it. That's never been my approach. My approach has always been, I'm going to find that corner that appeals to me, that corner that I feel like I can, at my own pace, I'll work hard, but at my own pace, I can make headway and make progress."
},
{
"end_time": 4799.889,
"index": 181,
"start_time": 4770.23,
"text": " and contribute something, bring it out to the world, and then maybe excite people to work on that. I mean, that's, you know, one of the big things that I did some years ago is called mirror symmetry, which was developing certain properties of higher dimensional spaces that are relevant for string theory. And when we were working on this, it was a really small community that was working. It was really us and one other group in Texas, Philip Kandelos and his group down in Texas,"
},
{
"end_time": 4827.056,
"index": 182,
"start_time": 4800.469,
"text": " And so it was really exciting. We were competing against each other, but we were in close communication. But it wasn't like a thousand other groups around the world were all battered and it's just us. And so, you know, we got ours, he got his results, our group got our results, he put it, people got excited. And then the field took off. And now like mirror symmetry has become a whole field of mathematics that has developed over decades."
},
{
"end_time": 4857.125,
"index": 183,
"start_time": 4827.363,
"text": " I no longer even recognize the things that happen in this field because it got so mathematical and so beyond my particular interest, which is really from the physics standpoint, but that's a great place to be. Work in your own corner, come up with something, put it out there, start a field and then the field takes off and God bless everybody who works on it. Your current interest is time or one of them, the emergence of time? Yeah, I mean that is a big question though. It's not as though"
},
{
"end_time": 4887.534,
"index": 184,
"start_time": 4857.551,
"text": " You sit down at your desk and you're like, OK, where does time begin? It's not a question you hit head on. I think it's the kind of question that you hit obliquely. And for instance, I would imagine that this work being done on wormholes and quantum entanglement, taking general relativity and understanding its inherent quantum mechanical aspects, I anticipate that insight into a deep question such as the origin of time will ultimately emerge from that."
},
{
"end_time": 4917.005,
"index": 185,
"start_time": 4888.029,
"text": " But not from a head-on approach, but rather from a more indirect approach. Do you agree with or find interesting Carlo Rovelli's views on time? He has this book, The Order of Time, and Lee Smolin has his own views too, which I believe is a realist, and then Carlo believes it's more relational or an emergent. And then Julian Barber. Yeah, so I think they're all interesting. Yeah, I think they're all interesting ideas. You know, I think that"
},
{
"end_time": 4931.971,
"index": 186,
"start_time": 4917.602,
"text": " Ultimately, the question of the fundamental nature of time is going to require scientific insights beyond those that we currently have. So I'm always interested to hear"
},
{
"end_time": 4960.265,
"index": 187,
"start_time": 4932.875,
"text": " thoughts on the nature of time and so rebellion the relational quality of space-time that resonates with me. I think there's definite powerful truth in there. I've seen papers of Lee's talking about the way in which time can emerge from an earlier temporal quality, a kind of way in which"
},
{
"end_time": 4982.91,
"index": 188,
"start_time": 4960.452,
"text": " The future is built from the present as opposed to already in some sense a temporal dimension being out there. I think it's quite interesting. Julian Barber. I remember being very excited about the initial ideas and then I read his book and there was one paragraph where I felt the heart of the idea was put forward."
},
{
"end_time": 5011.817,
"index": 189,
"start_time": 4983.575,
"text": " And it felt to me that he'd redefined the problem for me in a way that didn't feel as interesting any longer. I don't know if there's been developments since then. So it's all just to say that, yeah, time is a big mystery. Always interested to hear people's take on it. But in the end of the day, I think it's going to take deeper scientific insight. And what's happening now in string theory, broadly defined,"
},
{
"end_time": 5031.408,
"index": 190,
"start_time": 5012.073,
"text": " Before we wrap, I have a choice for you. We can have a couple physics questions or a couple more philosophical questions. Do you have a preference?"
},
{
"end_time": 5060.213,
"index": 191,
"start_time": 5031.698,
"text": " You can do a blend, whatever you think is good. Alright, so I know that you haven't explored category theory much but have you explored geometric algebra or geometric calculus? You know, I have dabbled but not enough to feel like I can provide any insight compared to the people who really know the subject so I probably would save those questions for subsequent guests who are more in that space. Sure, sure. What is the"
},
{
"end_time": 5082.312,
"index": 192,
"start_time": 5060.589,
"text": " Swampland conjectures. The swampland conjectures have to do with the following question. When you have a theory that does a really good job at describing say the physics that we can see, low energy physics is the physics that we can see."
},
{
"end_time": 5109.514,
"index": 193,
"start_time": 5082.824,
"text": " Does that theoretical description have what's known as an ultraviolet completion? That is, can that low energy physics be augmented into a theory that will agree with that low energy physics but work at arbitrarily high energies? Or is this just kind of an approximate theory that works at low energies but doesn't admit"
},
{
"end_time": 5138.899,
"index": 194,
"start_time": 5110.469,
"text": " an ultraviolet completion, ultraviolet high energy, doesn't admit a high energy completion. That is, it cannot be extended to arbitrarily high energies. And the Swampland idea is to delineate theories that may have a low energy incarnation, but don't admit a full completion to the entire energy spectrum. And the thought, according to some of the Swampland ideas, is that"
},
{
"end_time": 5166.817,
"index": 195,
"start_time": 5139.633,
"text": " The Swamp Plan is pretty big. Many, many of the theories that perhaps look like they may be candidates for theories that could be extended to arbitrarily high energies, they can't. They are fundamentally inconsistent. And that would be a potentially powerful idea, because after all, our goal is to winnow down the number of"
},
{
"end_time": 5192.534,
"index": 196,
"start_time": 5167.278,
"text": " candidate theories for the final theory and a final theory would work at any energy scale and if you can establish that a great many theories that look like they were contenders at low energies that they don't admit an extension to arbitrarily high energies then they get eliminated from the competition and so you get to winnow out a whole class of theories that don't"
},
{
"end_time": 5221.152,
"index": 197,
"start_time": 5193.114,
"text": " So what's meant by, you can take a low effect, sorry, a low energy theory and it works at the low energy, but then for some you may be able to augment them and then they're UV complete. What's meant by augment? What's a valid augmenting? So that what I mean is you can augment Newtonian theory to get special relativity. I don't know if like, does that mean Newtonian? Like, I don't know what augment means. Yeah. So, so usually"
},
{
"end_time": 5250.93,
"index": 198,
"start_time": 5221.357,
"text": " These ideas are formulated where you've actually got a mathematical formulation of a given theory, say perhaps even within string theory itself, and then you can simply ask, is this a self-consistent theory in the sense that you can use it, that very mathematical formulation, at arbitrarily high energies? And if you can't, then it properly should be"
},
{
"end_time": 5280.896,
"index": 199,
"start_time": 5251.442,
"text": " Consigned to the swampland because it doesn't admit an extension to or an application perhaps would be a better way of saying to arbitrarily high energies. And so, you know, this is an idea that Kumram Vafa and collaborators was, you know, instrumental in developing. And it, you know, I would say that it has flattened all of the"
},
{
"end_time": 5310.725,
"index": 200,
"start_time": 5281.544,
"text": " open questions when it comes to the theories like string theory but it has sharpened them because anytime you have a test in some sense for whether or not a theory is fully consistent works at arbitrarily high energies and I should say high energies mean short distances so does the theory work at arbitrarily short distances if it somehow is inconsistent at sufficiently short distances"
},
{
"end_time": 5337.705,
"index": 201,
"start_time": 5311.237,
"text": " That's a good thing for the project because now you can throw that theory away. Is consistency the same as self-consistency? Or are those separate? Usually. Well, usually. So unfortunately, our ability to probe the real physics of the real world at arbitrarily short distances is highly constrained by the equipment that we have. And so we'd love it."
},
{
"end_time": 5363.49,
"index": 202,
"start_time": 5338.473,
"text": " if consistency meant short internal consistency but also consistency with observations that we might make of you know physics down to 10 to the minus 25 or 10 to the minus 30 centimeters you know that would be beautiful but but because our ability to probe such realms is limited by our technology for the most part yeah we're talking about internal self-consistency"
},
{
"end_time": 5387.654,
"index": 203,
"start_time": 5363.865,
"text": " Okay, firstly, is internal consistency the same as self-consistency, just so I can get the terminology clear? Yeah, I mean, it's just a statement of as a mathematical structure, do you find any divergences? Do you find any incurable infinities or other mathematical maladies? Do they emerge"
},
{
"end_time": 5400.538,
"index": 204,
"start_time": 5387.961,
"text": " When you try to apply this theory to arbitrarily short distance or arbitrarily high energies. And yeah, you're not talking about observation at this point because you don't have the observations."
},
{
"end_time": 5429.411,
"index": 205,
"start_time": 5401.067,
"text": " Sorry, a self-consistent theory would be UV-complete and a UV-complete theory would be self-consistent or no? If you have a true UV-complete theory, almost by definition, it's consistent because the completion means that you've been able to formulate the theory in a way that you can apply to arbitrarily short distances, arbitrarily high energies, but UV-complete is. Let's end with your thoughts on simulation theory."
},
{
"end_time": 5454.616,
"index": 206,
"start_time": 5430.589,
"text": " It's certainly the case that as computational systems have become more and more sophisticated, their ability to simulate the real world seemingly is getting better and better."
},
{
"end_time": 5484.565,
"index": 207,
"start_time": 5455.691,
"text": " We see this with going from video games to the most sophisticated virtual reality. And so certainly one can imagine that at some point in the future we will have computational systems that are so sophisticated that they are able to have within them collections of bits and bytes running around that"
},
{
"end_time": 5511.63,
"index": 208,
"start_time": 5484.889,
"text": " May themselves have self-awareness. Now, that's the big unknown. Can you have a computational system that is itself self-aware, that it has some sort of consciousness? That goes back to the question that we started with early on. I don't know the answer to that, but let's assume the answer is yes. Big assumption. Let's assume the answer is yes. Well, then you're in an interesting circumstance because you can ask yourself,"
},
{
"end_time": 5533.439,
"index": 209,
"start_time": 5512.142,
"text": " How many real universes in the sense of solid tables and chairs are there? Well, we're kind of aware of one, and it's very hard to create new ones. If I challenge you to create a new real universe, you don't know how to do it. Create a new Big Bang, nobody really knows how to do that. But if I ask you how many of these"
},
{
"end_time": 5563.746,
"index": 210,
"start_time": 5533.951,
"text": " Simulated universes are there. Again, assuming that we've gotten to the point, say in the future, when we're able to simulate worlds of the conscious beings, there could be a gazillion simulated universes. You know, some kid just comes home late at night and flips on the computer and says, let me just simulate one more universe with these and these parameters, just flips it up and the computer just simulates it. And within that simulation are further conscious beings. So then the question to ask yourself is what's the likelihood"
},
{
"end_time": 5590.418,
"index": 211,
"start_time": 5564.309,
"text": " that right now we are in a simulation. And if you sort of play the odds in the most naive way, you say, well, there's only one real universe, but there are gazillion, gazillion, gazillion of these simulated worlds. And so the odds would seem to suggest that we are in a simulated world just by sheer force of the numbers and probabilities."
},
{
"end_time": 5619.77,
"index": 212,
"start_time": 5590.828,
"text": " So do I believe that? Do I think that we are in a simulation right now? I can't say that I do. If you're to really challenge me why I don't, I don't really have a good response beyond the fact that I've never seen a simulation that can do this. But, you know, that may simply be that the simulator is so good that the simulator is hidden from me. The fact that I'm in a simulation"
},
{
"end_time": 5649.241,
"index": 213,
"start_time": 5620.111,
"text": " And I agree that if I extrapolate from where computation was 40 years ago to where it is today, sort of exponential growth in its ability to do things that seem real, then, you know, don't go 40 years hence, assuming we don't blow ourselves up, go up a thousand years hence. And now you can really imagine that there are these simulations and we could well be in one of them. So"
},
{
"end_time": 5656.971,
"index": 214,
"start_time": 5649.923,
"text": " i don't feel like i have a strong reputation of the possibility that i'm in a simulation but"
},
{
"end_time": 5687.022,
"index": 215,
"start_time": 5657.602,
"text": " B.J.'s Wholesale Club makes holiday hosting so easy, we called in Thanksgiving's original host to talk about it. Pilgrim here. We could have used BJ's back in the day. Imagine stepping off a boat then foraging for your first Thanksgiving. It's a whole new world now. BJ's brings Thanksgiving right to your door with free same-day delivery on your first order of $100 or more. We're talking turkey, squash, pies, all at prices so good they'll knock the buckle right off your hat."
},
{
"end_time": 5715.196,
"index": 216,
"start_time": 5689.309,
"text": " Thank you so much for your time. It's been a pleasure. I do have a last question from Charlie from the Institute for Arts and Ideas. He sent this to me and he's like, Kurt, can you please, you're speaking to Brian, I would love if you could mention this. So I'll chat it here and I can say it aloud. If that's alright? Yeah, sure. I'll say it aloud just so that you can read it."
},
{
"end_time": 5741.049,
"index": 217,
"start_time": 5716.049,
"text": " Charlie Barnett from the Institute of Arts and Ideas says, hi Brian, almost a year ago to this day you were featured on a panel at the IAI, so the Institute for Arts and Ideas with Michael Shermer, Sabine Hassenfelder and Eric Weinstein. Eric Weinstein who was a mathematical physicist at Harvard said that string theory had a terrible culture in the 1980s that was in the process of resolving itself"
},
{
"end_time": 5768.712,
"index": 218,
"start_time": 5742.142,
"text": " In response to this, you sympathized and said that there was a sense of unreasonable exuberance that many thought string theory was the final theory, but it also seemed that Eric was slightly exaggerating how bad the culture was. What do you think he was referring to, and could you maybe comment more broadly about how one can ensure that bias doesn't creep into scientific theories? Yeah, I mean, you know, briefly put, there"
},
{
"end_time": 5798.797,
"index": 219,
"start_time": 5769.002,
"text": " was a sentiment in the eighties. I mean, I was there as in thick of it as a graduate student, mostly, not as a faculty member. And there was a sentiment that we were approaching the end of physics. It was naive, but it was genuine. It wasn't as though people were making it up. I mean, you can imagine, well, you can, but if you weren't actually part of it, perhaps one can't really feel"
},
{
"end_time": 5825.452,
"index": 220,
"start_time": 5799.189,
"text": " the visceral excitement that had taken hold of a segment of the physics community. I mean, there I was a graduate student at Oxford in 1984, 1985, and every Wednesday or something like that, when the preprints were finally delivered to the physics department, the graduate students, two others and myself in particular,"
},
{
"end_time": 5849.684,
"index": 221,
"start_time": 5826.425,
"text": " We would like tear open the envelopes to see the next result. And we take that paper and compare it to what we were doing. We'd go up and we were working like, you know, 15 hours a day. You know, I go to sleep at two in the morning. I'd wake up at seven. I'd ride my bike to the physics because it was just like, oh, my God, like it was all coming together, which is all just to say it was genuine."
},
{
"end_time": 5871.903,
"index": 222,
"start_time": 5850.026,
"text": " The excitement was genuine, but the downside of that kind of excitement is if someone's not working on string theory at that time, I can well imagine they feel like a complete outsider, that they're completely excluded, that nobody cares about what they're working on or what they are doing. And I know people"
},
{
"end_time": 5897.722,
"index": 223,
"start_time": 5872.227,
"text": " who have described that experience to me. And I don't know if that was Eric's experience or if there was something particular that happened. I just don't know. I don't know him personally. Sure, I've done that event and so forth. But I do know people who, from a more personal perspective, have described how alienated the excitement in the string theory community made them feel back in those days. And so I get it."
},
{
"end_time": 5924.855,
"index": 224,
"start_time": 5897.91,
"text": " And I wish it wasn't that way. But I guess the point that I was making last year and the point that I make again here, it wasn't malicious. It wasn't like folks said, let's exclude everybody else who's not working on this sacred meeting. It wasn't like that. It was just that people were so wrapped up in what they were doing and so excited by what they were doing that there wasn't a lot of the energy or time left in the community to pay attention"
},
{
"end_time": 5953.951,
"index": 225,
"start_time": 5925.503,
"text": " to things that were happening in the surrounding. And when it came to jobs, there were real implications for this. You know, in those days, more string theorists got the postdocs and got the faculty jobs because of the excitement. And you can well imagine that somebody who was working hard and doing really good work, but outside of string theory, maybe said, let me in. I want a job. Like I want a postdoc. I want to get it. And I totally"
},
{
"end_time": 5980.094,
"index": 226,
"start_time": 5954.633,
"text": " empathize with that. But it's just that when it's framed as those string theorists were like a malicious community that were sort of barring the doors against it, it wasn't like that at all. It was just coming from whatever Alan Green's, you know, irrational exuberance, you know, it was exuberant. And was it irrational? Not irrational, but it was perhaps a little too much. Because the more"
},
{
"end_time": 6003.507,
"index": 227,
"start_time": 5980.486,
"text": " seasoned researchers and physicists at that time knew that ultimately the excitement would die down and the theory would need to mature and be developed. And that's what we've been doing. So I think that's sort of my best answer that it was coming from a good place. It wasn't coming from a place of exclusion."
},
{
"end_time": 6021.613,
"index": 228,
"start_time": 6004.616,
"text": " Yeah, I need to be a little bit more active in that realm."
},
{
"end_time": 6052.039,
"index": 229,
"start_time": 6022.09,
"text": " Sometimes I use Twitter. My kids tell me I should use Instagram. Maybe I'll start doing that. I don't know, TikTok. Maybe I think I'm too old for that. But, you know, the World Science Festival is probably the best place. We are creating all sorts of, I think, really interesting content. And so people should sign up for the World Science Festival newsletter. And that's certainly where a lot of my focus has been in terms of bringing science to the public. And yeah, if you happen to be in the Toronto area on the 26th,"
},
{
"end_time": 6078.2,
"index": 230,
"start_time": 6052.363,
"text": " And you said next week is relative to when this goes out. Yeah, come by to the program at Roy Thompson Hall. I think you'll enjoy it. It's sort of an evening exploration of the universe from sort of soup to nuts. Great. And just to be clear, that's January 26th, 2023. Evening time, I'm assuming. Whatever it is, I'll put it on screen. Yeah. Is that being repeated? That talk being repeated at a different city that you can promote?"
},
{
"end_time": 6108.951,
"index": 231,
"start_time": 6079.121,
"text": " I'm just trying it out in Toronto to see how it goes. If the reception is good, then I can imagine doing it elsewhere. If you find yourself in New York at the end of May, we're going to do our first live World Science Festival since 2019."
},
{
"end_time": 6137.961,
"index": 232,
"start_time": 6109.241,
"text": " Because of everything, you know, we've gone fully digital, but we're going to go live again in the end of May of 2023. And that's coming up in, you know, five or six months. So it'll be a fun time in New York. And I'm going to do this program in New York as well. OK, I see. I see. OK, yeah, well, it's definitely keep me apprised about the World Science Festival because as Toh grows, sorry, the theories of everything channel grows, maybe there's something I could do to help promote it. And it was a pleasure, man."
},
{
"end_time": 6161.869,
"index": 233,
"start_time": 6138.916,
"text": " The podcast is now concluded. Thank you for watching. If you haven't subscribed or clicked on that like button now would be a great time to do so as each subscribe and like helps YouTube push this content to more people. Also, I recently found out that external links count plenty toward the algorithm, which means that when you share on Twitter, on Facebook, on Reddit, etc."
},
{
"end_time": 6188.797,
"index": 234,
"start_time": 6161.869,
"text": " It shows YouTube that people are talking about this outside of YouTube, which in turn greatly aids the distribution on YouTube as well. If you'd like to support more conversations like this, then do consider visiting theories of everything dot org. Again, it's support from the sponsors and you that allow me to work on toe full time. You get early access to ad free audio episodes there as well. Every dollar helps far more than you may think. Either way, your viewership is generosity enough. Thank you."
}
]
}No transcript available.