Speaker 1: Pushkin from Pushkin Industries. This is Deep Background, the show
Speaker 1: where we explored the stories behind the stories in the news.
Speaker 1: I'm Noah Feldman. The world has recently been gripped by
Speaker 1: the extraordinary and extraordinarily beautiful image of a black hole,
Speaker 1: a thing which we know allows no information or light
Speaker 1: to escape, and of which we therefore, strictly speaking, shouldn't
Speaker 1: have an image at all to make sense of this.
Speaker 1: At the level of logic, at the level of physics,
Speaker 1: and at the level of deeper meaning, we're thrilled to
Speaker 1: have with us today. Andy Strominger one of the leading
Speaker 1: theoretical physicists in the world who's made fundamental contributions to
Speaker 1: quantum gravity theory, to string theory, and has also worked
Speaker 1: extensively on black holes. Don't take my word for it
Speaker 1: that and he's the right person to talk to. He's
Speaker 1: one of every prize there is to win in the
Speaker 1: space of theoretical physics. And Andy is also a director
Speaker 1: of the Center for Fundamental Laws of Nature at Harvard.
Speaker 1: On top of that, he's also one of the co
Speaker 1: directors of the black Hole Initiative here at Harvard University
Speaker 1: where I'm speaking to Andy today. Andy, thank you so
Speaker 1: much for coming and joining great to be here. Ah. So, Andy,
Speaker 1: let's just start with the image, which is a great
Speaker 1: headline grabber and something that is extraordinarily beautiful, but which
Speaker 1: strictly speaking, isn't a classic photographic image, whatever the world
Speaker 1: may imagine. So say a word, if you will, about
Speaker 1: what we are seeing, what it is, and then from
Speaker 1: there we can move on to what it tells us. Okay, well,
Speaker 1: I'd like to back up a little bit. It was
Speaker 1: a hundred years ago that Einstein predicted with his equations
Speaker 1: that there would be black holes, and people have been
Speaker 1: arguing about them for most of the time, not believing
Speaker 1: that they exist. Einstein wrote a paper nineteen thirty eight
Speaker 1: saying black holes don't exist. Most people thought they didn't
Speaker 1: exist until probably the seventies. And how they behave, what's
Speaker 1: inside them, why they're there, has been a central debate
Speaker 1: in physics for the last one hundred years. I have
Speaker 1: spent the majority of my scientific career thinking about them,
Speaker 1: trying to understand them, along with hundreds of other people,
Speaker 1: and then all of a sudden to see it, to
Speaker 1: see a picture of it, like Wow, that thing is real,
Speaker 1: it's really it's really it's not. We're not the only
Speaker 1: ones who have that. You could be the deepest specialist
Speaker 1: and you're moved by it. I promise you that we
Speaker 1: have a bunch bore. It rocked our worlds to like
Speaker 1: see this thing that we've been talking about our whole lives.
Speaker 1: So there it is, you know, even though you knew
Speaker 1: it was there. We knew it was there. But there
Speaker 1: is a big difference between knowing something's there and seeing it.
Speaker 1: You know, maybe there was still that tidy bagging about
Speaker 1: I don't know, but it really is great to see it.
Speaker 1: It's a great thing actually to hear that from a physicist,
Speaker 1: because when non physicists like me, mere lay people, we
Speaker 1: instinctively have the feeling if we don't see something, maybe
Speaker 1: it's not there. And then the physicists tell us it's
Speaker 1: all equations, it's all logic, there are experiments that validate
Speaker 1: these things. Take it on faith, you know, like you'll
Speaker 1: never fully understand those things, but we know. And so
Speaker 1: to hear that you too, or even you like to
Speaker 1: actually see stuff as a kind of I don't know,
Speaker 1: there's like some epistemological relief to me. And hearing that, yeah, yeah,
Speaker 1: so what is it that we are in fact seeing
Speaker 1: a black hole, by definition, is a region of space
Speaker 1: and time from which no light escapes. So we're not
Speaker 1: seeing light from the black hole. What we're really seeing
Speaker 1: is light emitted by gases swirling around the black hole,
Speaker 1: things that we don't understand very well. And we're seeing
Speaker 1: the shadow of the black hole. So that dark spot
Speaker 1: in the middle of that picture, the absence in the
Speaker 1: middle of the breast, the absence in the middle of
Speaker 1: the picture is where the black hole is. One of
Speaker 1: the ways that was central too, or the main thing
Speaker 1: that was central to making this telescope able to see
Speaker 1: something so extraordinarily far away, was to turn the whole
Speaker 1: Earth into a telescope. How does that work? We get
Speaker 1: to the size of the Earth because we take about
Speaker 1: eight different telescopes located at different points around the Earth
Speaker 1: and we synchronize them and so it's of course not
Speaker 1: a complete lens covering the entire Earth, but it's still
Speaker 1: gives you a lot of resolving power if you can
Speaker 1: just grab the light at those separate points. And as
Speaker 1: an accomplishment, the creation of the image with all of
Speaker 1: its coolness is scientifically significant. Why for several reasons. First
Speaker 1: of all, it is in and of itself a spectacular
Speaker 1: technical accomplishment, one that would not have been possible ten
Speaker 1: years ago. It required many things. It required amazing improvements
Speaker 1: in the accuracy of atomic clocks, um, it required uh,
Speaker 1: bigger hard drives, bigger data processing capabilities, it recovered. I
Speaker 1: read at one point that the data was so much
Speaker 1: that it actually had to be flown from one place. Yeah,
Speaker 1: because the Internet couldn't accommodated. Right at Sheep himself, I
Speaker 1: saw lugging around these you know, discs with the you know,
Speaker 1: he would go down to Mexico, go up to the
Speaker 1: top of the mountain and lug lug it back. Of course,
Speaker 1: the whole team was working on it. But Shep is
Speaker 1: the director of is the direct and your your co
Speaker 1: director at the black the director of this event Horizon
Speaker 1: project at a great great scientist and uh, and the
Speaker 1: algorithm has also gotten some attention and deserves some attention.
Speaker 1: I take it produced by Katie Bowman, a recent post doc. Right, Yes,
Speaker 1: there were of course, the whole there's there's a big
Speaker 1: team of one hundred to two hundred people, and you know,
Speaker 1: all this kind of big science is done in a
Speaker 1: big teams and big teams now and it's it's the
Speaker 1: only way it could can be done. But number one
Speaker 1: of the big technical accomplishment. Number Two, there is the
Speaker 1: importance of having seen these objects you know, that should
Speaker 1: be shouldn't be underestimated. Number three, it's only the beginning. Um.
Speaker 1: One of the things that struck me when I saw
Speaker 1: the papers was, which I was not privy too before
Speaker 1: the the general release, was how little actual observing time
Speaker 1: they had when I first met Chapter ten fifteen years ago.
Speaker 1: This project was you know, it was it was a
Speaker 1: dark horse. It was it was not, you know, the
Speaker 1: center of astronomical efforts. Um. And it was a funny idea,
Speaker 1: but one that the more you thought about it, the
Speaker 1: more since it made Why was it Why was that
Speaker 1: just panenthetically? Why why wasn't it at the centerpiece of
Speaker 1: as you say, black hole so crucial, so important and
Speaker 1: seeing it would be a big deal, you know, because
Speaker 1: it wasn't. There many ways it could have failed, right,
Speaker 1: They had to increase their observational precision by many orders
Speaker 1: of magnitude over whatever what anybody had ever seen. What
Speaker 1: they did. It's like standing in Boston and reading the
Speaker 1: data on a quarter in Los Angeles. That is, that
Speaker 1: is the precision that they had to have to image
Speaker 1: this black hole. The general public tends to forget, I
Speaker 1: tend to forget that the funding of scientific projects is
Speaker 1: always a kind of a bet or a gamble. It's
Speaker 1: a beat, and when the odds of the success are
Speaker 1: relatively low, the funders are skeptical about putting too much
Speaker 1: money on that gamble. When people thought about it ten
Speaker 1: or fifteen years ago, did they think, well, if we
Speaker 1: get enough computing power, this is one of the things
Speaker 1: will fix. And it's a question of whether we'll ever
Speaker 1: get enough computing power, or was it rather a question
Speaker 1: of other aspects of the technical difficulty of doing it.
Speaker 1: He wasn't dismissed, and the thing was funded in it
Speaker 1: and it did happen, but it was not obvious. It
Speaker 1: was not obvious. You know, the Earth is just barely
Speaker 1: big enough to image this thing. It's also very important
Speaker 1: that the wavelength that they could access with this large
Speaker 1: collator array is one in which there isn't a lot
Speaker 1: of absorption between us and the black hole. You know
Speaker 1: that there isn't a lot of dust that blocks the
Speaker 1: light at that that wavelength. Right, So there were some
Speaker 1: coincidence that you know, Luck smiled on the project. It
Speaker 1: might not have been possible. I don't I doubt if
Speaker 1: you get cheppy, you could ask him, but I doubt
Speaker 1: he would have been certain you ten fifteen years go
Speaker 1: that it would work. But I was going on to say,
Speaker 1: they didn't get all that much observing time. Now clearly
Speaker 1: they'll get more, right, there will be better resolution, more
Speaker 1: observing time, they'll set one up out in space. So
Speaker 1: there we are entering an era. So this is the
Speaker 1: opening of that era of precision black hole astronomy. So
Speaker 1: let's talk about now what we can see and what
Speaker 1: we will see when we get more time, more observations,
Speaker 1: and the emergence of what you described as a new
Speaker 1: a new science really of precision black hole astronomy. You
Speaker 1: with some collaborators have been actually making predictions the way
Speaker 1: theoretical physicists like to do. You know, a theoretical physicist
Speaker 1: makes predictions and sometimes they can be tested in his
Speaker 1: or her lifetime. Sometimes it takes generations. In this instance,
Speaker 1: you've made a series of observational predictions the things that
Speaker 1: you expect can be picked up, and now that will
Speaker 1: turn to whether they will in fact be be picked up,
Speaker 1: which is dramatic and exciting. What kinds of predictions have
Speaker 1: you already been making and when can we expect to
Speaker 1: see results. I've been working with Alex Sasa, Delilah Gates,
Speaker 1: and Dan Coppetts, and we are very interested in what
Speaker 1: happens very near the horizon of of the black hole,
Speaker 1: right at the edge of that inner shadow, and remind people,
Speaker 1: just because it's never bad, to redefine it the event horizon. Yeah.
Speaker 1: So the event horizon is the boundary of the region
Speaker 1: of space time from which light rays connects escape. So
Speaker 1: in practical terms, it's the edge of that you're inside
Speaker 1: the event horizon, you're in the black holiness of the
Speaker 1: black hole. Yeah. Once you go inside the event horizon,
Speaker 1: you can never come out, and so your predictions relate
Speaker 1: to what's happening at that edge, right. And one of
Speaker 1: the things that we are very interesting in is that
Speaker 1: black holes can spin around like a top and it's
Speaker 1: believed that the M eighty seven, the black hole that
Speaker 1: we've just seen, is spinning at light speed or very
Speaker 1: near light speed. So there has been claims of this
Speaker 1: from other kinds of measurements in the literature, and a
Speaker 1: black hole which spins at light speed does some incredibly
Speaker 1: peculiar things. Is you get near the edge of the
Speaker 1: black hole, a long sort of funnel or wormhole forms.
Speaker 1: It's kind of like a tornado with a long spout.
Speaker 1: And as the black hole spins faster and faster, that's spout.
Speaker 1: It sounds like I'm talking about sub sides fiction stuff.
Speaker 1: But everything with respected black holes though, so go on
Speaker 1: sounds like I'm talking about sizes fiction stuff. But we
Speaker 1: maybe seeing this kind of black hole. Now the spout
Speaker 1: or the wormhole that goes to the horizon, the black
Speaker 1: hole actually becomes an infinitely long tube protruding out of
Speaker 1: the out of space doot, and that will lead to
Speaker 1: about to ask you where where the wormhole leads. But
Speaker 1: if it's infinitely long, the answer is, yeah, it leads
Speaker 1: to infinity. It goes, it leads to infinity. But before
Speaker 1: it gets infinitely long where the wormhole leads it goes
Speaker 1: into the rise of black hole, and once it crosses there,
Speaker 1: we don't know. We don't know what's inside a black hole.
Speaker 1: So the part of the wormhole is in the very
Speaker 1: edge of the wormhole is at the event horizon, right
Speaker 1: as it were, and then it extends infinitely away from
Speaker 1: the black hole and connects on to the space time
Speaker 1: that you and I live in, and that so we're
Speaker 1: seeing into what does sound like science fiction. It does
Speaker 1: sound like science fiction, but we're seeing it, you know,
Speaker 1: And how would that be seen? I mean, what would
Speaker 1: that as it were look like? We in our paper
Speaker 1: gave some very specific predictions about what the polarization of
Speaker 1: the light coming out will be. It's known that it's polarized.
Speaker 1: Not that's coming from the black hole, but the lights, sorry,
Speaker 1: the light and the halo. Yes, it's known that it's
Speaker 1: polar polarized, but the distribution hasn't been extracted from the
Speaker 1: data yet. I think they've already seen it. They have
Speaker 1: these mountains of hard drives the data they need to process,
Speaker 1: and they haven't extracted from that what the polarization is.
Speaker 1: Luck will have to shine on us for Are there
Speaker 1: measurements to be sufficient to prove what you've predicted? Yeah? Right,
Speaker 1: because they weren't there looking for what you predicted. Well,
Speaker 1: that's right, and also might not be this round might
Speaker 1: not be a precise enough measurement for our prediction to
Speaker 1: be verified or not. But I'd stress that our prediction
Speaker 1: is a prediction of the Einstein equation. It's just the
Speaker 1: Einstein equation in a very unusual circumstance, not like the
Speaker 1: predictions that Einstein made, where the effects of general relativity
Speaker 1: on the bending of light or in the Solar system
Speaker 1: they were small effects. Yes here, it's huge effect. Here
Speaker 1: it changes dramatically the nature of space and time, everything
Speaker 1: that we really have to to somebody even reimagine what
Speaker 1: we are, what we mean in ordinary language term. Yeah.
Speaker 1: So we think that if you were to go in
Speaker 1: a spaceship to near the horizon of M eighty seven,
Speaker 1: you would be forced to whirl around it. You couldn't
Speaker 1: just approach it straight on. There would be a force
Speaker 1: by the warping of space time that would drag you
Speaker 1: around like a tornado and pull you down this down
Speaker 1: the drain into the down drain at the speed of
Speaker 1: light through the wormhole. Yeah, bow the wormhole to the Yeah,
Speaker 1: and it would grab you well before you got to
Speaker 1: the event horizon. So, in practical terms, though it's outside
Speaker 1: the event horizon, you're descent into the black hole would
Speaker 1: begin a lot sooner than it. Otherwise it would be
Speaker 1: if it were really spitting all the way at the
Speaker 1: speed of light, it would grab you when you were
Speaker 1: infinitely far away from the event horizon, but suck you
Speaker 1: there in a finite amount of time by pulling you
Speaker 1: up to the speed of light. But when you say
Speaker 1: we grab you when so I'm just trying to get
Speaker 1: my mind around this and not so much succeeding when
Speaker 1: you say would grab you the reason you're infinitely far
Speaker 1: away is that sounds as though, well, we're infinitely we're
Speaker 1: at some distance less than infinitely far away from M
Speaker 1: eighty seven right now. Why doesn't it grab up? Oh,
Speaker 1: we don't know that, because we're not infinitely far away
Speaker 1: from the edge of the wormhole, and the wormhole could
Speaker 1: be infinitely long. I don't think it is. You'd have
Speaker 1: to be going absolutely at the speed of light for
Speaker 1: it to be infinitely long. But it could be very
Speaker 1: very long, and so we could be much farther away
Speaker 1: than it seems. I mean, the rest of the universe exists.
Speaker 1: The rest of the universe is not presently I take
Speaker 1: it currently captured by the wormhole right and spinning at
Speaker 1: some very rapid speed around the black hole, and on
Speaker 1: the way to the event horizon, we're not headed all
Speaker 1: headed that way, I take it right. So my question
Speaker 1: is why, Well, because we're far away week, but when
Speaker 1: you get to some critical point instance, all of a
Speaker 1: sudden it's a spinning black hole is surrounded by a
Speaker 1: science fiction region which was discovered in the sixties called
Speaker 1: the ergosphere. And life inside the ergosphere is very different
Speaker 1: than life in this room, and existence rather than life,
Speaker 1: because nothing's living once you get into the ergosphere. Anyone
Speaker 1: who enters the ergosphere, which is still outside the black holes,
Speaker 1: you you are forced to spin around in the in
Speaker 1: the tornado vortex outside the black hole, and the wormhole
Speaker 1: is a big extension of that. The wormhole is the
Speaker 1: is the vortex going Yeah, it is the vortex going
Speaker 1: down to the black hole. So we what we know
Speaker 1: really is our distance from the mouth of the wormhole,
Speaker 1: not how long the wormhole is. Now nobody thinks it's
Speaker 1: infinitely long, but it could be long enough to be
Speaker 1: in testing and long enough to make a signal. And
Speaker 1: how how will the observation of the polarization of the
Speaker 1: light that presently is visible at the edge of the
Speaker 1: black hole get you to some better understanding of the
Speaker 1: of the wormhole. Well, the worm it will verify the
Speaker 1: existence of of the wormhole, I say. And the polarization
Speaker 1: is not the only thing um. There are other things
Speaker 1: that you might try to to to measure. Now I
Speaker 1: stress it there. We're just one of and not even
Speaker 1: the most important, what of many groups who are in
Speaker 1: the vent Horizon telescope themselves are making predictions. Of course,
Speaker 1: they had to compare their their theory to the theoretical
Speaker 1: predictions to their observation to get their estimate that they
Speaker 1: published of the mass. We are especially interested in some
Speaker 1: of these novel aspects because first of all, because they're
Speaker 1: weird and interesting and they're there and we're seeing them,
Speaker 1: and also because they tie in with ideas about the
Speaker 1: quantum structure of black holes and what's inside a black
Speaker 1: hole in a very intricate way. And that question of
Speaker 1: what's inside is hugely controversial and fascinating. So the question
Speaker 1: of what's inside also philosophical, if I yeah, I venture
Speaker 1: to use that word. There are philosophical aspects to it,
Speaker 1: but there is a very sharp meaning to it because,
Speaker 1: as Stephen Hawking showed, if you wait long enough and
Speaker 1: even the you know, event Horizon team won't have this
Speaker 1: much patience. I'd be like a very very long time,
Speaker 1: the black hole will evaporate and what's inside using quantum
Speaker 1: effects will come out. And then the question is would
Speaker 1: the thing that came out, would what was inside to
Speaker 1: come out and have some information? And then there is
Speaker 1: an inside that we would ultimately see if we could
Speaker 1: wait long enough, which I think, yeah, more than billions
Speaker 1: moves it from philosophy to physics because there would because
Speaker 1: it's not an unanswerable question. Well, it's a question people
Speaker 1: could argue about. That's a separate, interesting question. What makes
Speaker 1: something a physics question as opposed to philosopher ques I
Speaker 1: was using a shorthand of imagining that physicists only like
Speaker 1: questions that, in principle could be answered. It's a question
Speaker 1: which can be answered with a goadoncan experiment when you're
Speaker 1: do in your mind? Yes, I thought, you can't get
Speaker 1: the funding to do it? Okay, right, So some people
Speaker 1: would say infinite time, Well, you don't have infinite time.
Speaker 1: Some people would say that physics is the study of
Speaker 1: questions you could answer with real experiments that could be funded.
Speaker 1: That's a pretty cramp though, view if it wouldn't cover
Speaker 1: a lot of your your earlier work, wouldn't cover wouldn't
Speaker 1: cover a lot of my work, right, And I think,
Speaker 1: to be fair, I don't think that's what most non
Speaker 1: physicists think. I think it's that would be a very
Speaker 1: hard nosed, predictive, pragmatist view, and it's not physics if
Speaker 1: I can't test it, you know, and get funding to
Speaker 1: test it. Yea. The laws of nature presumably should be
Speaker 1: resistant to being cabined by what we can fund. But
Speaker 1: what's exciting to me here is that this observation is
Speaker 1: touching the edge, possibly touching the edge of the things
Speaker 1: that bearing on the issues of people that people think
Speaker 1: about who want to understand what's really inside a black hole.
Speaker 1: So you mentioned your friend Stephen Hawking, also your collaborator
Speaker 1: who died not so long ago and with whom you
Speaker 1: did a lot of work over the years, but most
Speaker 1: recently you had been working on some pretty major projects
Speaker 1: with him, also connected to black holes. Yeah, tell us
Speaker 1: a little bit about that. Yes, Stephen, in his most
Speaker 1: famous work in the Seven Daies, showed that with an
Speaker 1: argument that is so simple and elegant that it has
Speaker 1: never been seriously questioned that when you include quantum effects,
Speaker 1: black holes are not completely black. That quantum effects allow
Speaker 1: a sort of the uncertainty principle about where the horizon
Speaker 1: of the black hole is allows a small amount of
Speaker 1: light and matter to slowly trickle out of the of
Speaker 1: a black hole a very slow rate. So those are
Speaker 1: big things, and let me try a very very lay
Speaker 1: person's attempt to make sense of that. If we imagined
Speaker 1: determinative locations and laws of physics, then nothing escapes the
Speaker 1: black hole. That's what makes it a black hole. But
Speaker 1: one of the key points of quantum theory is it
Speaker 1: precisely you can't pin down the exact location of every
Speaker 1: quantum phenomenon. And since you can't pin it down exactly,
Speaker 1: that puts enough wiggle room, if you will, into the
Speaker 1: equation that there is some information in the black hole
Speaker 1: that might be capable of being discovered. How's that for
Speaker 1: a first order? That's right. So quantum mechanics says that
Speaker 1: the horizon and the black hole must fluctuate around a
Speaker 1: little bit, according must be slightly uncertain, and so that
Speaker 1: gives just enough wiggle room for a few quantum particles
Speaker 1: to escape from inside the black hole at a slow rate,
Speaker 1: so that you began with describing Hawking's famous nineteen seventies
Speaker 1: that was forty years ago, yep. And he gave an
Speaker 1: argument that the information about how the black hole was
Speaker 1: made would not escape, would not come out with this
Speaker 1: leak of energy and particles and so on. Things would
Speaker 1: come out, but not the information about how the black
Speaker 1: black hole came to be made. He claimed, the present
Speaker 1: does not determine the future and cannot, even in principle,
Speaker 1: be used to reconstruct the past. Bad news for historians,
Speaker 1: bad news for hystories for people who like free will
Speaker 1: in the future maybe, but bad news for physicists because
Speaker 1: it's equivalent to saying there aren't absolute laws of physics,
Speaker 1: because a law of physics is supposed to predict the
Speaker 1: future from the present. It was a very simple argument,
Speaker 1: and people didn't like the conclusion. It had been questioned
Speaker 1: in many different ways, but none of the ways in
Speaker 1: which it was questioned really stuck. So a few years
Speaker 1: ago I found, while investigating other problems in physics, I
Speaker 1: came across what seemed to be an error in the
Speaker 1: original flawed assumption in his original reasoning. Moreover, the nature
Speaker 1: of the flaw suggested a research program for understanding what
Speaker 1: really did happen. And I explained this to Stephen and
Speaker 1: he was very excited about it, and I just say,
Speaker 1: this is also it's a great model of what scientific
Speaker 1: collaboration can be and isn't always You find a flaw
Speaker 1: in an important claim by another famous physicist and you
Speaker 1: call him up and you say, hey, there's a problem,
Speaker 1: and that's collegial of you, and then he responds positively,
Speaker 1: and that's collegial of him. This is the way it's
Speaker 1: supposed to work in the textbooks. Yeah, and it really
Speaker 1: does work this way for the for the most part. Yeah,
Speaker 1: it's heartwarming. It's not like this in my end of
Speaker 1: the academy. I promise you that. Well, it may be
Speaker 1: related to the fact that there's no money in my
Speaker 1: branch of science. I know there's a there's a there's
Speaker 1: a money in those prizes. But go on. So he
Speaker 1: and I and his colleague Malcolm Perry, he had some
Speaker 1: ideas about how to proceed on this and to make
Speaker 1: sense of it, and so we began a very active
Speaker 1: and productive collaboration which went on for the last three
Speaker 1: years with life and we're pushing forward in that direction.
Speaker 1: It's looking promising, but we haven't delivered the goods, right.
Speaker 1: We don't know yet that there isn't some reason this
Speaker 1: is a technical issue rather than the fundamental right. When
Speaker 1: you were describing how you came up with the original
Speaker 1: thought that led to this collaboration, my reaction was you
Speaker 1: were describing how you were thinking about something else in physics,
Speaker 1: and then you hit upon reason to think that one
Speaker 1: of Hawking's original assumptions was inaccurate. And it's struck me
Speaker 1: that's a very andy way to go about things. One
Speaker 1: of the key features of your contributions across the whole
Speaker 1: range of areas where you've worked is that you find
Speaker 1: and see correspondences between different areas of thought physics, math
Speaker 1: that other people have never hit upon before. That's like
Speaker 1: the Andy move, as it were, and it's quite a move.
Speaker 1: So well, I don't think I have a pattern on
Speaker 1: this move. But it's the structure of the field the
Speaker 1: physics is. You know, there's many It's interconnected in surprising ways,
Speaker 1: and it often happens. Maybe I'm lucky enough that it
Speaker 1: happens to enough times that I'm not sure it looks
Speaker 1: like a coincidence, but maybe coincidental in nature, but it's
Speaker 1: not coincidental in you. But anyway, go on, and you know,
Speaker 1: maybe one could say, you know, our creator didn't have
Speaker 1: so many ideas that he kept using the same one
Speaker 1: over overget and you solve a problem in one area
Speaker 1: and it has a translation into another area. So that
Speaker 1: hints at a kind of set of structures of unity.
Speaker 1: I mean, you're sort of kidding about reusing the same idea.
Speaker 1: What you really mean is that there is an underlying
Speaker 1: unity and we are describing different parts of reality in
Speaker 1: different ways. We've got these mathematical tools or these physics
Speaker 1: tools to describe something, but we're actually describing a more
Speaker 1: unified underlying phenomenon. Yeah, we have many ideas and we
Speaker 1: often don't realize that they're the same idea. And is
Speaker 1: it your belief that there is some directionality here? I mean,
Speaker 1: now I'm aiming for something bigger, as it were, even
Speaker 1: bigger than you know, than the wormhole and the black hole?
Speaker 1: Are you a believer in direction in physics towards more
Speaker 1: and more unification of our theoretical knowledge? Sometimes people talk
Speaker 1: about a grand unified theory string theory, to which you've
Speaker 1: made fundamental contributions. Is sometimes described as a step in
Speaker 1: the direction of a grand unified theory or an aspiration
Speaker 1: in that direction. I'm asking you to put it along
Speaker 1: the line here. You know, the honest answer to that
Speaker 1: question is, I don't know. People work in different ways.
Speaker 1: Some people have beliefs that they think that that is
Speaker 1: how nature works, and they relentlessly pursue demonstrating the physical
Speaker 1: reality of their beliefs. Others just take the mathematical equations
Speaker 1: and follow them and see where they lead. And you
Speaker 1: see yourself in the latter camp. I'm somewhere in between.
Speaker 1: I have things I believe in, but I pride myself
Speaker 1: in being ready to drop my beliefs when they don't
Speaker 1: measure up to the equation. The equations are the final arbiters.
Speaker 1: The equations and the experiments are the final arbiters of
Speaker 1: truth in our field, and many people have, including you
Speaker 1: know Einstein. Einstein had very strong beliefs about how things
Speaker 1: should be should be, and that got him through special relativity,
Speaker 1: general relativity, and the beginnings of quantum mechanics. But then
Speaker 1: he had beliefs about the way the world should be
Speaker 1: that were being countermanded that we're being own by his
Speaker 1: own equations, and then the experiments that were validating those equations,
Speaker 1: and that reduced his his his productivity. M He did
Speaker 1: pretty well, He did pretty well. Then he did pretty well.
Speaker 1: But at some point he believed things that weren't true.
Speaker 1: He believed that quantum mechanics was wrong. He believed their
Speaker 1: word black holes, he believed their word gravity weight. You know,
Speaker 1: he had some raw beef, wrong beliefs that he got
Speaker 1: stuck on. So it interfered with his being able to
Speaker 1: move on to make the next set of He might
Speaker 1: have come up with even more fundamental things if he
Speaker 1: had been able to keep on pushing. That's right, that's right.
Speaker 1: So that's an argument that you may need some beliefs
Speaker 1: to get you started. Yeah, but there needs to be
Speaker 1: some kind of a reflective equilibrium where at some point
Speaker 1: you have to start believing your equations. Yeah, you know,
Speaker 1: it's always a conflict between sticking with what you believe
Speaker 1: in and not giving up, and being too stubborn and
Speaker 1: not being flexible enough. The real truth is it takes
Speaker 1: all types. You know, there's some people who have an
Speaker 1: idea and pursue it in the face of unreasonable hardship
Speaker 1: and difficulty, and everybody's saying no, and everybody's saying no,
Speaker 1: and some of those people turn out to be right.
Speaker 1: Now people turn out to be right, but most of
Speaker 1: them fall by the way side. Yeah, you need some
Speaker 1: of You need people with unreasonable beliefs. You need people
Speaker 1: who are ready to drop their beliefs. You know, it
Speaker 1: takes a village. Let me ask a final question about
Speaker 1: how these different pathways to understanding the world are going
Speaker 1: to play out in the black hole context. Yea. When
Speaker 1: you started working on black holes, as you said, there
Speaker 1: was still a view among lots of people that there
Speaker 1: were no such things right, and now we're in a
Speaker 1: very different place. We've seen one. Yeah, does that take
Speaker 1: some of the thrill out of it? Does it seem
Speaker 1: you know? I mean, it's nice to be right, But
Speaker 1: there seems like there's a stage of, as you said,
Speaker 1: great observational astronomy in the space of black holes, which
Speaker 1: is important and will expand our knowledge and maybe give
Speaker 1: us radically new ideas about the world. But somehow seems
Speaker 1: to be confirmatory of what you and others predicted and
Speaker 1: what is actually now believed to be true. Is there
Speaker 1: some it takes. I mean it's thrilling now, but ten
Speaker 1: years from now, will some of the thrill will be
Speaker 1: gone in working on something which everyone acknowledges exists. No,
Speaker 1: I think it's only getting more interesting. We can think
Speaker 1: of this. The last few years, or this observation even
Speaker 1: is kind of a historical marker. You know, a hundred
Speaker 1: years ago the existence of black holes was predicted. Now
Speaker 1: they've been seen in the most straightforward way. So going
Speaker 1: forward there will be better and better observations. But we
Speaker 1: still have this huge puzzle. Yeah, the godon Can experient.
Speaker 1: What is the result of the Godonkan experiment? What's coming
Speaker 1: out of the black hole? Or equivalently, what is inside
Speaker 1: the black hole? Then you know there's a fundamental contradiction
Speaker 1: in the laws of physics as we currently understand them.
Speaker 1: So that's what makes it so exciting. Something has to give.
Speaker 1: It's that the thought experiment poses a contradiction between different
Speaker 1: things that we're we are committed to. All the things
Speaker 1: that we believe to be true. Can't all be true.
Speaker 1: Something which we are completely at this moment unwilling to
Speaker 1: give up as a truth about the universe must actually
Speaker 1: be wrong, and the fact that that contradictions was recognized
Speaker 1: forty years ago by Hawking and has sat there. As
Speaker 1: the years have gone by, the longer it's sat there,
Speaker 1: the more that we've realized what central importance it is.
Speaker 1: So somehow the observational astronomy world and the theoretical physics
Speaker 1: worlds have converged on black holes as the most interesting
Speaker 1: and things around and it is. I'm pretty confident that well,
Speaker 1: first of all, I there's no reason we can't ultimately
Speaker 1: solve this problem. And the fact that it has sat
Speaker 1: there for so long, I think there is a consensus
Speaker 1: in the community that we can't solve the problem without
Speaker 1: a fundamental new insight into the structure of the universe
Speaker 1: at the same revolutionary level as quantum mechanics or relativity.
Speaker 1: That it's not a technical problem that we missed a
Speaker 1: factor of two somewhere. So that's the holy grail. That
Speaker 1: is the holy grail. It's an exciting thing that black
Speaker 1: holes have become come to center stage and observational astronomy
Speaker 1: at the same time as in theoretical physics. We don't
Speaker 1: have a roadmap how we're going to talk to each
Speaker 1: other and close that gap. But we're thinking here on
Speaker 1: a hundred year time scale, we might not even have
Speaker 1: found the city where the whole grail is hidden, but
Speaker 1: we've maybe found the continent, and now we're gonna have
Speaker 1: to keep exploring. But it's a pretty big deal to
Speaker 1: have found the continent. That's a big deal to have
Speaker 1: found the kind we know where we're looking and now.
Speaker 1: And I think you know, Although I'm loath to draw
Speaker 1: too many non physics metaphoric conclusion from physics, the idea
Speaker 1: that sometimes we're in the grips of contradictory views and
Speaker 1: something's got to give, we need some new account to
Speaker 1: make it work out is about as good a lesson
Speaker 1: to take away from black Holes as I can imagine. Andy,
Speaker 1: thank you so so much for your for your brilliant
Speaker 1: thoughts in your time. Thank you Eddie, thank you Noah.
Speaker 1: When I see an image like the image of the
Speaker 1: black hole, I'm filled with wonderment. The mere accomplishment of
Speaker 1: human beings, to be able to see something so far away,
Speaker 1: to conceive of it, to make sense of it. That's
Speaker 1: the kind of thing that really hits me where I live.
Speaker 1: It makes me believe that being human is actually worth something.
Speaker 1: After all, we can actually know things and achieve connection.
Speaker 1: But you know what, when I listen to Andy, somebody
Speaker 1: who actually understands at the most profound level what these
Speaker 1: discoveries are, I'm even more struck by the wonderment that
Speaker 1: he feels than the wonderment that I feel. He's not
Speaker 1: jaded at all. He spent a lifetime working on black holes,
Speaker 1: and to him, where at the crossroads of excitement where
Speaker 1: things are only going to keep on getting better. That's
Speaker 1: genuine scientific exploration. That's genuine scientific collegiality and collaboration like
Speaker 1: the kind that Andy has done with Stephen Hawking. And
Speaker 1: it makes you think not just that the universe is
Speaker 1: an amazing place, but maybe we at our best when
Speaker 1: we're not fighting and we're searching for the truth. Are
Speaker 1: in such bad people? After all? Deep Background is brought
Speaker 1: to you by Pushkin Industries. Our producer is Lydia Geane Coott,
Speaker 1: with engineering by Jason Gambrell and Jasonstkowski. Our showrunner is
Speaker 1: Sophie mckibbon. Our theme music is composed by Luis GERA
Speaker 1: special thanks to the Pushkin Brass Malcolm Gladwell, Jacob Weisberg
Speaker 1: and Mia Lobel. I'm Noah Feldman. You can follow me
Speaker 1: on Twitter at Noah R. Feldman. This is deep background