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Suzanne
Treister THUTOAH - The Holographic Universe Theory Of Art History Interview with Thomas Hertog and Stephen Hawking Thomas Hertog is a Belgian cosmologist at KU Leuven university and a key collaborator of Professor Stephen Hawking. This interview includes passages by Stephen Hawking from a lecture given at the Pontifical Academy of Sciences at the Vatican on 25 November 2016, used with permission and at the suggestion of Thomas Hertog.
Thomas Hertog: So yes, I am interested in questions to do with the Big Bang. The Big Bang was conceived first incidentally here in Leuven by Georges Lemaître, who figured out on the basis of Einstein’s theory that the universe must have had a beginning in time, which is a shocking finding really, time just doesn't go on indefinitely but thirteen billion years ago there was a genuine beginning. But Lemaître didn't say very much about what that beginning was about, and so we investigated it. Suzanne Treister: So, in relation to the project I've been doing for CERN would you be able to describe your conception of the holographic principle and would you say it's different from the way theorists at CERN might describe or conceptualise it? Thomas Hertog: The general idea of holography is that the reality of our perceptions, space and time, is to some extent emergent from something fundamental, in other words that there is an underlying hidden description of reality which is not anchored so to speak onto our usual perceptions of three space dimensions and one time dimension, but is somehow holographic, meaning, it's playing out on a surface. But there is a discussion as to what that surface should be, where this should be, what the bits of information are which then encode our familiar reality and there is a debate among scientists how holography really works. Some scientists are saying that it's a dimension of space which emerges holographically, which is holographically projected out of a hologram let's say. If one of the dimensions of space is holographically emergent then you would think that the hologram lives on some distant surface around our universe so to speak. But that is very strange because you might ask, well how did that surface get there? The data we have about our universe are here and not there? The idea of a dimension of space that is emergent works I would say, in the mathematical laboratory of theorists you can conceive of universes which are nothing like ours, but which are boxed in and which have a clear boundary around them and then you might think that is the way holography works, everything is happening on the boundary and you reconstruct what's happening inside, but our universe doesn't have an obvious boundary and so I'm a little skeptical that this is really the way we should think of holography. Stephen Hawking: It was at a conference in the Vatican, in 1981, that I first put forward the suggestion, that maybe time and space together, formed a surface that was finite in size, but did not have any boundary or edge. Together with James Hartle from the University of California, I worked out what physical conditions the early universe must have, if space time had no boundary in the past. Thomas Hertog: I tend to think of holography in a different way. I tend to think that it's rather the dimension of time which is holographically projected and that the hologram, that the holographic world, is really a kind of representation of our spatial reality, based on the bits of information that we have here and now, and that holography, the idea of projecting an extra dimension, comes about on the basis of our data here and now when we try to reconstruct our past, all the way back to the big bang. That is really also the kind of realisation so to speak of holography that comes out of my work with Hawking quite clearly in the model of the universe that we've developed, the dimension that we see holographically emerging from something fundamental is the time dimension and not so much any of the space dimension. Stephen Hawking: Hertog and I, have recently studied eternal inflation, from a different viewpoint. Our approach is based on the concept of holography, in string theory. Holography says that Einstein’s theory of gravity and space time, is equivalent, or dual, to a theory without gravity, that is defined on the boundary of space time. We have used holography, to excise the phase of eternal inflation in our past, and replace it by a dual theory, defined on the global exit surface from eternal inflation. This amounts to a refinement of the no boundary proposal, in which our universe does have a boundary in the past, that is at the threshold for eternal inflation. The dual theory defined on this past boundary, provides an approximate description, of the transition from the quantum dynamics of eternal inflation, to a universe with classical notions of space and time. Suzanne Treister: So, in terms of this, how do you feel about my theory, the holographic universe theory of art history. Do you think that artists might have always sensed the potentially holographic nature of reality and do you think the whole of art history might have been on one level an attempt to describe the holographic reality of our existence. Thomas Hertog: When I saw your work, purely intuitively, at a qualitative intuitive visual level, it struck me that in contrast to what the scientists were saying in the background, it struck me that you were rather trying to invoke a notion of holographic history rather than an extra spatial dimension, so at the intuitive level you could say it resonates. Of course as with many ideas in science, many ideas in science have these predecessors in the world of arts, in the world of philosophy, literature and so forth, so we can go back to Plato's allegory of the cave which also has some notion of holography and the idea that there is a kind of more perfect world out there of course has featured in the arts for centuries. Suzanne Treister: So it's like you're always looking at a landscape into the distance. So you can't see behind it then. Thomas Hertog: Yes. Suzanne Treister: No. Thomas Hertog: Yes. Suzanne Treister: If you can't fly like a bird and go over, zoom into that landscape then in fact you're just kind of seeing a landscape like you'd be seeing it in let's say an old master painting where the mountains in the way distance are those pale blue things, like in one of those Flemish paintings... Thomas Hertog: Yes. Suzanne Treister: Probably in a museum around the corner from you, where there are those nice pale blue mountains with just a haze at the back, and you can't... get there. Thomas Hertog: Exactly, and a big part of that is precisely because we are kind of evidently looking out at the universe from within. We don't have this bird's eye view as you were saying, from outside the universe. I think most people would agree we are somewhere within the universe. But you see it's a bit of a challenge to properly take into account our perspective as observers within the universe, to take that into account in the form of a physical theory which you write down with mathematical symbols. You see the mathematics easily leads you to believe that you can do away with that sort of nasty detail and look for some absolute truth behind the Big Bang. I think this has been a bit of a misguiding assumption. Suzanne Treister: Is there something beyond that? You know, there's the issue then there's the fact the observer is involved in it, and is there a third thing do you think, as well? Maybe that might be a way of getting around it? Because you know how like you had cybernetics and then you had second order cybernetics which included the observer, so what if it was third generation, what would be that third thing, angle? Thomas Hertog: Well maybe holography is the way. If I get rid of the time dimension, using holography, maybe that helps? Suzanne Treister: You were mentioning that before, that maybe time should be just taken away. Thomas Hertog: When I say this as a physicist, what we mean is that of course you could use it for all practical purposes. What we mean is that in the fundamental description of physical theory it would not feature, it would rather come out from other entities, I mean in the case of the way our current moulds of holography work, we have these extra dimensions emerging from the correlations, the entanglement between different parts of the system, between different bits of information so to speak, and so that's a curious way to look at time evolution, right. When we go further and further back in time it's as if we sort of reconstruct this dimension from bits of information which are somehow present here and now. It's kind of strange. Suzanne Treister: That is strange, because they don't exist, do they? Thomas Hertog: What does not exist? Suzanne Treister: Those things in the past. Thomas Hertog: They, well exist becomes a bit strange, yes. Suzanne Treister: I know, but just using the english language momentarily, as you've just said, you're constructing things from only the bits in the present. Thomas Hertog: Yes. Suzanne Treister: So that's all that there is on one level. Thomas Hertog: Well yes indeed at some level. It would be a totally different, unfamiliar, strange representation of reality. Not in terms of the usual space and time which we are familiar with and which is very practical, but in terms of something completely impracticable, unfamiliar, bizarre collection of particles and fields which are entangled in various different ways. However when we go back to the Big Bang, our usual way of thinking about reality in terms of space and time becomes very unpractical, in fact that's the problem with the Big Bang, it's the origin of time, it's saying that the way we usually think about reality is not going to work very well, it's breaking down, there's a limit to that. Suzanne Treister: Can you just extrapolate a bit about how holography might become more relevant when you're thinking about the Big Bang? Thomas Hertog: In a way the Big Bang is a problem of the origin of time, we go back and Lemaître and Hawking and Penrose, they're all telling us that if you go back and you keep thinking in terms of space and time physical theory just blows up, it explodes, it doesn't have anything to say. That's been regarded as a problem in physics because if that's the case we will never be able to explain the nature of the Big Bang, we will never be able to explain or to understand why our universe is the way it is. That's the Big Bang singularity, and out of a singularity any kind of universe can emerge, it would be just a limit of science so to speak. Suzanne Treister: And that's a holographic way of thinking about it. Thomas Hertog: Yes, because one dimension is gone. Suzanne Treister: Ok. Thomas Hertog: So the hologram is a kind of timeless, purely spatial representation of reality, very abstract, very unfamiliar but very useful when you go to the Big Bang. Just like a normal hologram would be a projection of a volume of space onto its surface, here I am projecting a time evolution on a surface too. Suzanne Treister: And do think any of the things that you've been describing have a kind of parallel in this video which people are watching as they hear you speak? Thomas Hertog: Well qualitatively yes, because in the video you are trying to evoke a history projected onto a surface. I'm looking at that disc as a kind of timeless representation of a whole history which flashes by, which is kind of different moments in time, different periods, are kind of superimposed onto each other, so to speak. That's what came to mind while I was watching that, that the disc is also precisely the kind of geometry which features in our work on holography. Stephen always liked to think about physical theory in a timeless manner, even going back all the way to his work in the 1980s, he has always been very keen on getting rid of that time dimension, so that's an idea which has been lurking in his mind for decades. And when you do so, geometrically, you are led to think about the universe and its history in terms of everything playing out on a disc and so this was very very, this resonated, the fact that I saw that disc in your work very much resonated with the way he and I for years thought about the universe. Many conversations started by drawing a disc. It's as if the entire history of the arts is compressed onto this purely spatial disc, but still it takes a while, it takes like 16, 17 minutes, and in a way this is a tension in my work with Hawking too. We are trying to get rid of this dimension of time but of course you don't quite fully succeed because whenever you relate the physical theory to our observations the time dimension pops up again, creeps out. It's only when we reach the Big Bang, in a way, that we truly succeed. There, it is as if you reach some sort of timeless, but also informationless state, it's more like an epistemic horizon, I don't know whether you see that in your.... Suzanne Treister: The problem is, that if I reduced the time to zero, well would it still be there? Thomas Hertog: Well, ok so now this is precisely the same sort of state that sort of emerges from our mathematics when you reach the Big Bang, the dimension of time disappears, but also all the information goes out, in a way there is nothing to say anymore. Suzanne Treister: No and let's say with this video, let's say that I worked on it for a longer period of time and I gradually reduced it down and reduced it down and then let's say I gradually took the final frame out and saved it, and somewhere, somewhere there would be a record of the history of the making of it, even though it didn't have any time left in it. Thomas Hertog: That is correct. Suzanne Treister: It's correct isn't it. Well what would that mean? Thomas Hertog: I don't know.
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