Episode 35: Physics and Relationalism: An Interview with Julian Barbour

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[00:00:10]  Blue: Welcome to the theory of anything podcast We have a special guest here today Julian Barber who? his books the Janice point and the end of time I have not read them, but Saudia keeps telling me about them and they Were a very big part of my interview with Saudia And so we decided we wanted to actually talk with Julian Barber about some of his theories And he has some really very exciting ideas that I had never heard of before So I actually am very excited to have a chance to talk with him and to ask him questions directly So we also have with us. Saudia and cameo here today. So. Hey, everybody say hello

[00:00:51]  Unknown: That’s me

[00:00:53]  Green: Welcome Julian. Yes, welcome. You’re welcome. And thank you very much for your time So

[00:00:59]  Blue: Saudia, I’m going to turn most of this over to you because honestly, you’re just smarter than me when it comes to physics so I

[00:01:08]  Green: Just know more physics

[00:01:10]  Blue: that’s all I don’t know about smarter, but

[00:01:12]  Green: All right, Julian. So this is really exciting for me because you know Your ideas have been a big inspiration for me when I was interested in quantum gravity when I was introduced to general relativity in my student days Just a whole idea of background independence kind of intrigued me and I feel like you your approach It really took me I think it made me appreciate physics at a deeper level to be honest with you Then I had ever gotten from any other books I’ll be honest with you and up till this day I feel like, you know, you make Classical physics general relativity approaching them fun because of the way like the type of questions that you’ve asked and how you address them So I wanted to start by asking you about just an intuition that most physicists seem to have About that there should be some sort of and I’m not saying every physicist believes in that but Most physicists seem to think that there is some sort of an underlying unity in the universe And it seems to me that your work I feel like has taken that more seriously than I ever saw anybody Take could you maybe and Comment on that and particularly I’m kind of referring to your Machian approach To physics What does it mean that there is an underlying unity in the universe? And would you also as you go through it maybe tell us a little bit about how that that comes about in your theory? Maybe even talk about I guess I’ll let you start and then we could ask questions. Maybe as we go along

[00:02:42]  Red: Yes, well certainly Mach has been a great influence for me and Basically, he was reacting very strongly as had Leibniz before him to Newton’s ideas of absolute space and time. So Newton imagined space as The way I like to describe it as as a block of translucent ice in which you could draw lines and then you could imagine that Some object moves along these straight lines Because they’re there in the block of ice and equally he imagined that time flows uniformly and In that case then you can say that the The object is moving in a straight line at a uniform speed But the problem that Mach pointed out is that you can’t see Space it’s invisible and What about time if Newton says it flows uniformly without reference to anything else that’s happening Well, how do you see time? I mean we don’t see time What we see is objects and we see How they change we see things change so Mach has two sayings, which I always repeat slightly shortened perhaps one one which is Is is often quoted which is it is utterly impossible to Measure the changes of things by time Quite the contrary time is an abstraction at which we arrive by means of the changes of things and the other one is He he says the the universe is given once only with its Relative motions alone Determinable, so that’s my starting point and I think That’s not far away from what Leibniz said in a famous Disagreement with Newton’s ideas quite a lot earlier And I think that’s very intuitive. So Then the question is how do you turn that into a theory and

[00:05:11]  Red: That’s really what I’ve spent something in well over 60 years It’s it’s 59 years since I started thinking about these things I’ve worked with very good collaborators and the idea of the unity of the universe I think can I always start with just three particles because then you can really do something of Interest that now what I do assume is that I assume geometry or geometrical relationships Galileo said he did attempts natural philosophy without geometry is lost and I think I think that’s very true. So To give you an idea of how I think about the unity of the universe just imagine that there are three particles in it They’ve they will at any instant. They will form a triangle. So that’s a unity that in many ways a triangle is is the Is the geometrical figure with which we’re very familiar. We can all imagine a triangle now If if those three particles for the entire universe that triangle is is is everything So what can we say about it? We can’t say that it has any size Because there’s no ruler outside that triangle to say how big it is But what we can say is what is the shape of the triangle now? The shape of the triangle is determined by the ratios of the sides So a triangle has three sides so you can form the ratio of those three sides And those determine the internal angles of the triangle which determine the shape of the triangle I’m assuming that it’s in Euclidean space and There you have a deep unity. You you you just can’t get away from that. So How How far does that answer your question?

[00:07:08]  Red: Well, let me just say that if I only had one particle There’s nothing much you can do with that because you can’t form any Ratios so for me, it’s very important that you can always form ratios of things of the same kind so distances the three sides of the triangular all things of the same size so you you form ratios of them and If you had just one particle if you can’t do anything with that if you have two particles Well, you could say there’s a distance between them But you can’t take a ratio of one thing You’d always just get one you would divide the distance by itself and it always have one So nothing could change. So the great thing about three is that things can change so How how do you react to that Sadia?

[00:07:58]  Green: No, I think that is beautiful. This kind of highlights that relational View that you hold and that that you’ve really taken seriously One of the things that I kind of I was wondering ask

[00:08:09]  Blue: a clarifying question Quickly, so you just you just mentioned that there’s no sizes with with three particles There kind of is in that they could have different sizes relative to each other So what you’re really saying? I think is there’s no absolute size But rather you can only real like if you had a triangle that was each side was 10 There’d be no difference between a triangle with each side 10 each side 100 What would matter is that they all have the same ratio between themselves?

[00:08:41]  Red: Yeah, it’s it’s the ratios account and I’m Invisiging an idea idealized situation where the particles are really points. They don’t have any size. They are just literally points one of the really main ideas that we have in shape dynamics is that there is no Ruler outside the universe that that’s I mean tell that to the Marines That there’s something out there that we can measure the size of the universe by so all you can say suppose the universe did just consist of three points that they’re always at the vertices of a triangle All one can objectively say about it is that one side of the triangle is Shorter than a different side and you could say meaningfully by how much it might be exactly one half the length and things like that. So basically You’ve got three sides of a triangle, but there’s only two ratios. Those are pure numbers and shape dynamics is just insisting that everything we say about the whole universe should be expressed in terms of ratios like that.

[00:09:52]  Blue: Interesting. Okay. Thank you. And you also started to mention that there’s an assumption here that the points are infinitesimally Infantly small. Is that also a part of the assumption when we’re talking about there’s no absolute sizes. That’s really as a model.

[00:10:14]  Red: When Newton created dynamics. He talked about bodies and then within a few decades, mathematicians like Euler and others had Idealized that to talk about point sized bodies and point particles and the mathematics is perfectly okay. Now, There’s still a lot of uncertainty really in the physics community to this day about to what extent you can talk about point particles or whether you should talk about Fields, which is just a distribution of intensity. So I wouldn’t say that The point particle that the that the particles are exactly points is truly significant. The really much more important thing is is the ratios that it’s we’re talking about kill numbers.

[00:11:08]  Blue: Okay, thank you. That answers my question. Sorry, go ahead, Salim with whatever your previous question was

[00:11:13]  Green: Well, I had a previous question. But since there is another thing related to that, I’ll just ask now that those so the point particles or whatever the stuff there is how does I mean, correct me if I’m wrong in this that aren’t masses soon to be like aren’t aren’t the assuming that there are actually masses is masses and assume concept. Even though I understand that at the end the ratios are left behind. Does it matter if you have masses that are unequal versus all equal masses, even

[00:11:50]  Red: sure Certainly, you can assume that these point particles have masses and as long as you recognize that all that will count is the ratios of the masses. And in Newtonian theory, you assume that the masses remain constant. So basically, if you have 10, 10 particles, you can, you can, you can give them masses, but then you take the ratios of those masses. So you really only have nine independent ratios and they are all pure numbers. So the One definite guiding principle of shape dynamics is to express everything in pure numbers and it’s so it’s very convenient and easy to construct a model with point particles, which is why at this stage we’re doing that and that already opens up all sorts of interesting possibilities which to my surprise don’t really seem to have been seriously considered in theoretical physics or cosmology up to now.

[00:12:59]  Green: And when you see you’re also assuming a sort of like a shape dynamic form of the Newtonian potential right in there.

[00:13:08]  Red: Yes, that’s quite right. So the the the Newton gravitational potential they the that it exists between two particles so that you have particles that have mass one and mass two. And so you multiply those masses and you divide by the distance between them. So that’s got things that are not ratios, the the the masses are not ratios and the, and the distance is not a ratio, but then you to if you have A large number of particles that the total potential for the whole complete set is is all those products of the masses divided by the separations between the respective particles and you add that all up. And that is the Newton gravitational potential. So what we then do is multiply it by a quantity, which is called that the Center of mass moment of inertia or rather it’s square root, which is equal to what is called the root mean square length. So this is this is a quantity which has the dimension it’s a length. So if you multiply something which is one over a length and you can potentially is one over a length. So if you multiply the whole thing by something which is Which is a length, then you take out the length. So that’s got to rid of the dimensions in in the length and then you do the same with the masses you divide by The something that’s got an appropriate power of the masses. So the the moment of inertia has a mass in it. So you have to divide by an appropriate part of the masses and then you get something which is called the shape potential and that’s been used by people who study Newtonian gravity for a long time.

[00:15:07]  Red: But we’re promoting it to much more significance than than they have, but it’s a well established concept. So, so that’s how we introduce the Newtonian gravitational force in in that manner again as a pure number.

[00:15:25]  Green: I guess the thing that intrigues me is that how big of a part the ontology where You know, like, okay, there are masses, for example, that because we know that there are masses and they are correlated with each other. Using, you know, through the Newtonian potential, but which I understand how the in, you know, how, you know, eventually in shape dynamics, they’re pure ratios, but I was thinking that what if instead of masses, it was something else. You know, which would also impact, say, the type of potential. So I guess in that sense, what I’m wondering is that it to me it feels like there is There seems to be some sort of something prior to just shapes. Please. I mean, correct me if I’m wrong that is that something that You know, I mean, don’t you feel like maybe there is something prior Simply because, like I said here, obviously, we are talking about masses and their correlations are in terms of the Newtonian potential. But what if that was not the ontology. What if he wanted to take shape dynamics to a different theory. I mean, I guess, electromagnetic magnetism wouldn’t be that different if you have electric charges, but but what if there was some other basic elements with their associated potential,

[00:16:45]  Red: but I think there are this. This is something which has got to be developed, but basically Over the history of physics to two sort of precise notions of develop one is is the one of point particles. And as I say that was made firm in in the 18th century, really a few decades after Newton had made his discoveries and then bit by bit, the field notion, the notion of a field developed in in optics light was explained as a wave phenomenon and then Faraday had the idea of fields of force and and lines of force in in in electric and magnetic fields and then Maxwell put that together into his wonderful equations of electrodynamics huge triumph of theoretical physics. And then a few decades later Einstein did something even more remarkable which was create his his field equations in general relativity and in all those cases fields had replaced point particles, but basically you’re dealing with the same sort of things. Instead of having point particles with masses or mass ratios you have field intensities and you have directions of the fields that that they the Faraday lines of force run in a particular direction everybody knows the the famous experiment where you Sprinkle on filings over a magnet and you see the lines of force. So you can do shape dynamics with with those sort of concepts and in the 20th century you’ve had this huge success where physicists have gone beyond Maxwell’s theory of the electromagnetic field, and they’ve made huge progress with understanding the other interactions the above all the strong and the weak interaction, which is added on to the electromagnetic and the magnetic

[00:18:54]  Red: interaction and they’ve shown how to unify them in in it’s not a perfect unification but it’s it’s very impressive how they’ve managed to unify the forces now. In principle, all of those forces are represented by analogs of the new potential but they’re expressed in terms of fields and not point particles but in principle. I think it is possible. We’re a long way from developing shape dynamics to do that, but the possibility is definitely there. And one of the key concepts that we have in in shape dynamics which is what we call the shape potential but it’s also the complexity. I mean we give it two different names. There is an analog of that in in Einstein’s theory it’s related to three dimensional geometry. So, there’s a lot of work to do but I think the possibility of doing it is is definitely there.

[00:19:59]  Green: I guess what I’m wondering is that in taking the form of the potential in the theory, aren’t we admitting something maybe a little bit more than just pure relations. I guess that’s what I’m kind of thinking about that, that even though understand that we have pure ratios, but there is a form of the potential, it is one way rather than some other way. And in in the form of the potential, is it possible that you know we have admitted something which goes maybe beyond relationalism, even though the potential is purely relational. I don’t know if I’m clarifying my question in a good way. I guess it comes down to really what I really wanted to ask you was that would you consider yourself a relational purist, or do you think that there might be something more to the world. Do you think that when we’re talking about masses versus charges, could there be something intrinsic that you think that relationalism might miss out that in some shape or form we’re admitting but but we’re just looking at it in like at the level of just relations.

[00:21:04]  Red: Well, I certainly have a lot of confidence in relations and ratios. What is really the whole story of the universe is because of another matter, and quite why the Newton potential has the form it does is is a big issue. I certainly think that the real if if something is really made all the progress in in physics in understanding the world that has happened. It’s all developed out of the application of geometry. The geometry is not the Euclidean geometry and the facts of Euclidean geometry are not far removed from our everyday experience. And Galileo has this wonderful saying which I always quote heated attempts natural philosophy without geometry is lost. And there are certain very basic facts in geometry about right angles, the shapes of triangles you get then from them you get trigonometry. You can also get spherical trigonometry about how angles and distances on the sky are related to each other, which incidentally was developed before plane trigonometry was because of applications in astronomy that that happened about. 100 150 years before the common era. So that’s, that’s, I think all that physicists theoretical physicists at the moment have been able to work with really. And in fact, really geometry is come to dominate physics more and more as as time passes. So that’s my justification for as, as regards the particular form of the new potential. It’s very, very interesting structure that it has, particularly when you put it as as the shape potential when you when you make it dimensionless, because there are, there are two. So once you’ve got the idea of a set of points, and they needn’t have masses you could say they all have the same mass.

[00:23:24]  Red: There is one number which is called the mean root mean square length. So you, you take, you take all the separations between the particles you square them you add them all up and then you take the square root of that. That is called the root mean square length, and it’s the most obvious thing you would want if you want sort of some average of the diameter of sort of a lot of points in space if the points in space were, were bees and you had a swarm of bees it’s basically the diameter of that swarm of bees. And then there’s another length that you can define, which is sent, which is actually just the Newton potential or rather the inverse of the Newton potential so that’s called the mean harmonic length. So if, if you had a mathematician who knew all about Euclidean geometry, and nothing about gravity at all, but was asked to come up with a mathematical expression which characterizes how much a collection of points is clustered or is uniformly distributed. The most obvious thing it would come up with would be that ratio of the root mean square length divided by the mean harmonic length, and lo and behold, what is it, it’s the Newton potential made scale invariant.

[00:24:48]  Green: And

[00:24:48]  Red: I think that’s very striking indeed.

[00:24:51]  Green: Interesting and I guess you also connected it to this concept of complexity that you talk about right the. Well,

[00:24:58]  Red: that’s right because it is it is exactly the same. It is the quantity that we call the complexity and that behaves in a very interesting way when you actually look at actual Newtonian solutions how they how these point particles interact with each other this. This, it’s, it’s first of all what is really governing the behavior of those particles. If you consider them as a model universe, if you have a finite number of particles and you say that’s my model universe, it is actually that quantity which governs their behavior. And it is also, it’s also the size of that universe because how do you measure the size of something you take a, you take a measuring rod. And you, which you say, six inches long, and you, and you, you measure the, you, you, any object you’ve got the width of your table by seeing how many times that ruler goes across it. So, given those, if you have those particles, just the particles are nothing else. Is there some way in which you could say how big it is well you could imagine that the, if there were two particles close to each other relatively close to each other, you could you could say well they define that that separation of those two particles defines a ruler I’m going to say that is my ruler. And then you can say, well how big is, is, is, is the whole universe.

[00:26:32]  Red: Well, a more sensible way to do that would be to take the average of the short separations and the average of the large separations and law and divide the average of large separations by the average of small separations and you would say that’s the intrinsic size of the universe, and that learn below again is the new potential a scale invariant it’s what we call the complexity. It’s really quite remarkable how much just comes out of that one mathematical expression. Yeah,

[00:27:04]  Green: that is fascinating and it’s also interesting to me that that that you and your collaborators have mentioned that how, when we look at general relativity in its standard formulation that there seems to be could you maybe tell us a little bit about how the scale and versus shape dynamics. Is there some sort of sense in which the, because, because you guys have pointed out that there is the scale seems to be a little bit more absolute in a sense and in the standard formulation of general relativity or

[00:27:47]  Red: Well, the scale is in the standard formulation of general relativity scale is put in in a in a rather unsatisfactory way I have to say I mean I have a one of my collaborators. He says, and he’s a cosmologist and he says that the, the first lecture when students go to their first lecture on cosmology they’re told that size of the universe is is a is a nominal quantity at the given instance so. They’re told that what you say is that the side or the volume of the universe now if it’s if it’s closed up on itself as opposed to an infinite universe but I much prefer to imagine that the universe is is in some sense is a true unity and and closes up on itself in three dimensions like the surface of the earth does in two and that’s a that’s a big that may be wrong. And that’s got to be admitted but if that’s okay then under those circumstances what. Budding cosmologists are taught is that you say the size of the universe now is one and that’s a nominal choice. And then the size of the universe at any other time is some fraction of that it may be larger or smaller. And then my collaborators says, and thereafter the professional astronomers seem to completely forget about that and carry on as if size is absolute and you can see countless examples of that if you read the literature. And in a way, so they they know, they know so to speak in their brains that there is no ruler outside the universe but in their gut they still continue to believe in it, and the same really goes for time.

[00:29:47]  Red: And this is very interesting because Einstein towards the end of his life, about seven years before he died, he wrote some autobiographical notes and he said that he had actually committed a sin when he created general relativity because he said it. The theory introduces two completely unrelated concepts, one is the concept of the space time at metric, which tells you how far apart in space things are two points or how far apart in time they are. And then he said, the theory brings in something completely unrelated without any without coming bringing it out of the theory, which are rods and clocks, and these rods and clocks measure spatial separation and and time separations. And he said that is any calls he says that literally is a sin. And he says that a decent theory should develop a theory of rods and clocks from within the fundamental equations of the theory, and he admits that he wasn’t able to do that. And he said it was a sort of admit that it was a makeshift, and he said that this, this sin should be rectified at some stage, and I just think it hasn’t been properly done. And I think it’s sitting right at the heart of relativity theory and cosmology to this day, when you really look at how general relativity works now this was as a dynamical theory this was shown in the 1950s. This was developed by on a bit days and miss now that’s called the ADM Hamiltonian formalism Hamiltonian dynamics, and simultaneously it was done by Dirac in the 1950s. And Dirac was actually so surprised at what he’d found he said, this result inclines me to believe that four dimensional symmetry is not a fundamental property of the physical world.

[00:31:53]  Red: And that’s actually what brought me started me thinking about well what’s time then. So, and then later on, a method was developed. There’s this very complicated issues in general relativity how you can actually use it. And well, let’s stop at that stage because we might come back to that because you may want to come back and answer some question me about what I’ve just said.

[00:32:21]  Green: Yeah, actually I was wondering that how far do you think shade dynamics has gotten to addressing that question and by the way this is one of the reasons that I’ve thoroughly enjoyed following your work. It’s really made me appreciate physics at a deeper level. And the sort of questions like what you were saying about cosmology it’s one of those things you do come across. And you do wonder what all that means and then somehow, because you’re just bombarded with so much you’re learning so much that you just tend to overload but you actually didn’t let go of it and actually kept asking those questions. So how far would you say that shape dynamics has gone how. Like, what do you feel at this point in time how successfully has shaped dynamics. Address that question that Einstein left and took the operational route. And I think, I think we’ve gone

[00:33:17]  Red: quite far, but not yet within Einstein series we have shown really how the theory comes. What Einstein was calling for actually does come out of Newton series very beautifully. And now, first of all, Newtonian. When you take relational ideas seriously which go back to Leibniz criticism of Newton’s concept of absolute space and time and to ends marks very forceful criticisms in the 19th century. And try and just say that so much said you really got to think about how the whole universe works and he suggested that the inertial motion which is so important in Newtonian theory. And it was to formulate the idea of inertial motion that the body moves. If it’s not affected by the forces that it either stays at rest or it moves uniformly in a straight line at a uniform speed that was why I introduced the notions of absolute space and absolute time to give some mathematical meaning to that statement. And Mark said, there’s something manifestly wrong with this because you can’t see you can’t see absolute space and absolute time, and he conjectured. And this is what Einstein then called Mark’s principle that somehow the universe in its totality all the masses in the universe, somehow or other through and as yet unrecognized mechanism cause is what is actually guiding the particles in their inertial motion that inertial motion is, is the local manifestation of the interconnection of the whole universe. And that’s, I think I can say that is the contribution that my Italian collaborator Bruno batote and myself. I think one can say we definitive definitively showed that that makes sense. And if you have a universal point particles, we showed how you can explicitly implement that idea of Mark’s.

[00:35:33]  Red: And in fact, when you then look at the formalism of general relativity the dynamical structure of general relativity that aren’t of it days and Missner found and Dirac at the more or less at the same time. You see that. And if the universe is spatially closed up on itself, then you see that Newton’s that that the way batote and I showed it for in with point particles, this basically the same structure is realized within general relativity so in if the universe is closed up on itself. And so I think I’m encouraged by that. And so this is, this is shaped dynamics now it’s the really important mathematics that goes behind this was first of all the work of Dirac and an ADM. And then it was followed up another 1012 years later by Jimmy York in, in North Carolina and Nila miracle, the Irish collaborator with whom I worked for 10 years for 10 years. They did some very important mathematics, which is called solving the initial value problem, which literally lays out the mathematics and proves that it works in a very impressive way. In, in much more sophisticated way than batote and I did in 1982, but the, the overall reason why it works is essentially the same. It’s an implementation of Marx principle in that case there.

[00:37:18]  Green: Oh, I’m sorry. I just

[00:37:21]  Red: wanted to say that encourages me.

[00:37:24]  Green: No, you kind of answered actually one of the questions I wanted to ask at the beginning about that mocking unity that you know how in standard physics you you kind of take the inertial frames of reference for granted and you never really get an answer of okay, how does how do the inertial frames of frames of preference come about, or even the question of what, what, what, what equi locality means, for example, or if a bucket is rotating how do we know that it’s, you know, how do we meaningfully say that the if there’s water in the bucket that, you know, clearly we see that there is even acceleration some absolute sense but why can’t be according to relativity say that the universe around it is just rotating around it. Maybe I’m putting too many things here but I guess what I really wanted to ask was, so it seems to me that there seems to be some sort of almost like a non local type connection. I mean, I know non locality is a loaded word and different people mean different sometimes it’s used talked about in different ways, but seems to me like there is some sort of almost like an instantaneous type of a connection that determines our locality or whereby locality seems to be more of an emergent thing than anything, would I be wrong in saying that or No, but let me start off by saying that geometrical relationships are non local just just imagine just suppose.

[00:38:59]  Red: I mean this is this is just a fact about Euclidean geometry so you have. So, first of all, there are things that are measuring rods, and I call these gifts of nature, I mean, you wouldn’t find them anywhere near the big bang in time, but shall we say surveyors in Egypt, three 4000 years ago could take bamboo canes and they could survey fields which they almost certainly did. And with these bamboo canes they might have discovered Pythagoras’s theorem it’s entirely possible. And the great thing about measuring rods is that they they they don’t misbehave unless something is done to them so you could start off putting to bamboo canes next to each other in Alexandria. And then you could take one of them to Luxor and bring it back again and lay it next to the one that had stayed all its time in Alexandria. And you’d find that they were the same length and if it if they weren’t still the same length, then it’s never too difficult to find out what’s gone wrong somebody came along and cut a bit off one of them. You know, or one of them’s got a bit hotter so it’s expanded a little bit. So this is this wonderful thing about measuring rods. Now with measuring rods. You can measure distances between a finite number of points. So if there are, there’s a formula it’s very easy. So if you’re in three dimensions and you’ve got n points. So you take n, then you multiply it by n minus one, and you divide by two and that’s the number of distances there are between those end points. And if there’s only three points,

[00:40:56]  Red: those separation those distances that you found must satisfy the triangle inequality but they don’t satisfy an algebraic equation. But if you have five or more such points. These are these can be as far apart as you like, they satisfy algebraic relations they satisfy equation certain expressions have to be equal to zero and zero is a very special number. That’s telling you something very profound about interconnections in the world. And in Euclidean geometry, these connections, these relationships can be as just as big as you like so to speak they they they can. I mean, the overall size is meaningless but they can hold between any number of particles you can, you can have these relationships holding between 1000 particles. And that is, I would say this is a incredibly tightly knitted so geometry is what holds the world together. I like to quote from the opening scene of Gertus Faust where well and one of the early scenes where Faust is in despair about the universe and the world and what it is and he says, well, I’ll quote the German. And thus, he asks bus in innocent devote to summon health and my translation in doing this is, what is it in its innermost core holds the world together, and my answer inspired by Galileo is geometry. It’s incredibly non local. So, so if if those points, if the if the distances between the points change as they change those relations have got to stay valid, and that’s happening non locally, there’s there’s nothing local about that. So this is why I think you don’t have to be alarmed at all about Mark suggesting that distant parts of the universe are having an effect here, because geometry is already like that.

[00:43:15]  Red: And it’s it’s the, it’s the law. The question that really counts is, what is the law that operates when the distances change, and that’s, there is a natural way to, there’s a rather natural way to say what that law is. And in the case of point particles, that’s the one that Bertotti and I found, and it’s a restriction so you still get Newtonian motions but they’re restricted they say that a very fundamental quantity called the angular momentum of that system of particles treated as the whole universe must be exactly zero and somewhat related but this is to do with time. It’s very, it’s very, I won’t say it’s quite so definite as the vanishing of the angular momentum, but you can also argue that the total energy of the system must be exactly zero. And I don’t think this, once you’ve got used to it and you’ve accepted the fact that geometry is this incredibly tight, knitting together of the whole universe at a given instant that the this Machian fact about how the universe changes its shape should hold. I don’t think that’s at all surprising.

[00:44:32]  Green: Interesting. And then I guess I kind of wanted to, so that would require that the universe is finite right or would that also require, I guess the universe have to be closed as well or Yes,

[00:44:48]  Red: it would, it would certainly. I mean, there is perhaps some possibility that this some sort of approximation to much ideas might work in an infinite universe but I think it’s much more attractive to have one that is is is is a true unity. Now that that doesn’t mean so the particle model is not completely satisfactory because you always have to have a finite number of particles you can make it bigger and bigger and bigger, but you’re still going to hit up against the end and say there’s a variety so as you look out at the as astronomers look back to as far as they possibly can in the universe to whatever it is 300,000 years after the Big Bang, they see what is called the the microwave background. I’m sure you’ve seen that that it’s all over the place this image of the microwave background looking like a rugged ball or an oval with with spots on it. And those are the fluctuations of the temperature that they’re one part in in 100,000 tiny fluctuations in the temperature but there are variations now mathematics is so to speak infinitely deep those fluctuations could actually so they they they spread over a relatively small fraction so that their temperature variations of one part in 100,000, and they have a diameter I’m not quite sure what the diameter is but you’ve seen that thing it it looks like a speckled rug a ball or an egg. You might even go and make it so it looks like one of these beautiful Easter eggs that they paint in in Eastern Europe.

[00:47:00]  Red: And there’s no reason why those that detail should not be infinitely deep because you can go to you can go to infinity in the sort of infinitely deep. And you could sort of sort of use a microscope to look ever closer and you would find that the structure goes on forever it’s mathematically perfectly possible so in that sense when you go to the field ontology you could literally have an infinite universe, even, and it would be a true unity because it would close up on itself. In

[00:47:36]  Green: other words, we’re thinking one way to think of the fields would be you could, you know, to think that there is some sort of almost like there’s no bottom layer that you could keep going deeper and deeper but you’re always going to find relations that, you know, you’re always going to find relational aspects where everything is just kind of related at different levels. Is that what you’re saying. Yes, it is that deep. Yes, it’s perfectly possible if you have, if you have waves.

[00:48:09]  Red: I mean if you have a loop of string. This is like string theory. If you have a loop of straight or an elastic thing. You have waves of different wavelengths they have nodes where the where the fluctuation is zero. I like a violin string. And there’s a longest wave. This is this one, the lowest frequency and the longest wavelength. And then you, you just go all the way up to infinity and then in quantum field theory that’s called, then you’re really getting into the ultraviolet. So when you go to the infrared you come to an end but when you go to the ultraviolet you don’t, you can go on dividing forever. And so I mean that’s just the same you can imagine standing in the middle of a circle and and seeing dots around the circle of equally distributed. First of all there might be just one dot in one place then there would be another dot exactly opposite then there would be four dots or three dots equally spaced with 120 degrees between them, and you could just go on filling dots forever and it’ll never stop.

[00:49:30]  Green: But I guess from our point of view we will always then see the dynamics to be like the universe, the dynamic, the universe to be approximately closed dynamically closed, because there’s always more to it is that would that be the right way of thinking about it, that from our point of view, you know, we will see it as kind of approximately dynamically closed because there’s always more to the universe I don’t know if I’m thinking. Well,

[00:49:58]  Red: we wouldn’t, we wouldn’t, we wouldn’t see if it really is goes down forever, I mean, you know that the structure, the structure never comes to an end. And we would never, there would be a limit to what we could, we could see. And I mean that that’s just a technical practicality, but in principle it could go on down forever.

[00:50:29]  Green: All right, and I guess a related question that I had was, I was listening to David Sloan’s talk on that shape then dynamic workshop I kind of looked at his paper to where he, he basically did a scale free I guess reformulation of the current period of cosmology, where, starting from a scale free action. And there, there was some sort of a friction like term that that he talks about that that we’re seeing here that where, if you give up on the scale if the scale is intrinsic, then you end up getting this friction like term. In the cosmology model so would that be kind of suggestive of this type of openness to the universe.

[00:51:20]  Red: Yes, I guess so yes no I mean, David’s mathematics is is is is very interesting it’s one way of looking at things so. And in fact, actually there’s another way which also introduces a friction type thing which already came in in. That was actually before my tour, so my back in 2015. I, Tim Koslovski in Flavia Mercati had this paper in physical review of letters identification of the gravitational arrow of time. And in that, we said that you could look at the way Newtonian theory behaves as as if there was a friction term so basically the start the great form of dynamics which evolved in the in the 19th century was by this great Irish mathematician Hamilton, and that’s called Hamiltonian dynamics in the late 18th century a beautiful form was was developed by the mathematician Lagrange and that’s called Lagrange and dynamics. And they both derive really from Newtonian dynamics but they’re very elegant ways and very particularly the one that Hamilton devised came up with this is incredibly powerful and very beautiful. And there’s no friction in that so that will describe a pendulum with small oscillations well it will describe a lot with large oscillations and things like that so. But you can have also friction terms in the dynamics but then the dynamics is not Hamiltonian. But the interesting thing is, if you if you take the scale out of Newtonian theory and there are various ways of doing it and David has got one particularly elegant way of doing it, or starting without it even rather.

[00:53:28]  Red: But it was my collaborators who did the mathematics in our paper in 2015, you can take the scale out of new out of Newtonian theory in its Hamiltonian form and when you do that, you get a modified form of dynamics which which seems to have friction in it but it’s friction of a rather interesting form because normally friction will bring motion to a stop. I mean if you roll a ball on a sticky table it will come to an end the motion. But it, this type of friction doesn’t things go on forever but they, it looks as if they’re subject to friction. All right, in other words like an open system right it doesn’t necessarily have to be where it’s just losing energy or, but it’s suggestive of more of an open system right. Well, once you take out energy has energy has is a dimension full quantity so when you take it out it’s, it’s, it’s not really such an appropriate concept. You, you, you see you, if, if you have a Newtonian system for which the energy is non is zero, then the shapes change in a certain way if the energy is is non zero then the shapes change in a different way there’s a different law that governs the way the shapes change.

[00:54:59]  Green: So you’re saying that’s better to think in terms of because like you said that we were saying that the energy of the full if we apply to the whole universe is zero. So we have to think more in terms of how it affects the changing the shape changing right.

[00:55:14]  Red: Yes, well the, the, the thing about the thing about just only looking at the shapes is that it removes all the redundant part of your description if you, if you have the ordinary Newtonian description in essentially, well, nowadays students are taught to, it’s in an inertial frame of reference, but you start off for example with. You say, you say where the center of the mass of the system is that’s not that’s that’s three arbitrary numbers way where you imagine that the center of masses somewhere in space, then you, you say, what is the direct if it’s got angular momentum you say what is the direction of that angular momentum in that space. So that’s another three things. So that’s another two that’s a direction, then you say what the magnitude of that is so you bring in a lot of things which are nominal at the start. So there’s a lot of redundancy in the normal description. So, if you then, but if you then use Newton’s equations to find out to get a solution. Then you can throw away all of the information about where the center of masses what the orientation of your angular momentum is and what the overall size is, and just look at the succession of shapes. And in doing that, you’ve done two things, which I think are very important and should tell you that’s the way to think about the universe as a whole. First of all, you’ve thrown away every single bit of information which is redundant that you, you can get rid of, but you haven’t thrown away one single bit of it, which is essential.

[00:57:07]  Red: So, if I, if you give me a Newtonian solution in the conventional way, I then just take out of it, the successive shapes. And then I give those successive shapes to a different mathematician, that different mathematician can reconstruct a Newtonian solution. It will be one of a whole family of possible reconstructions of the same thing because it will be that it will have the same succession of shapes but it won’t. It won’t have the extra things which come in because of this redundancy, which really goes back to the way Newton formulated dynamics in the first place. Which is fine if you’re talking about something moving relative to the surface of the earth, because the earth provides a frame of reference and you know what it means to say I’m going to start at the top of the world of the Empire State building in New York. And I’m going to do it at a certain time because the time can be defined by the rotation of the earth relative to the stars, sidereal time. But if you’re talking about this in empty space and where the clock which is not realized by actual material things you’re in, you’re just bringing in a whole lot of. Well, they’re not really there I mean this inertial frame of reference is really a swindle it’s bogus and it is actually confusing students who should really be taught really. That’s not the way dynamics was discovered dynamics the law of free fall was discovered by deli layer in his studio in Padua near Venice he was at the University of Padua which was the university that was associated with Venice.

[00:58:55]  Red: And how did he find the law of free fall, he rolled balls down a smooth, gently sloping smooth plane, and he measured how long it took them to travel a certain distance. And I think there were various ways but one way which would certainly have been adequate would be to measure it by water clock how much water flows out of a tank of water, as the ball rolls a certain distance. And that way he found a very beautiful law which he thought was very exciting. It was the odd numbers law he said if in the first unit of time, the ball rolls one unit of distance in the next it will roll three in the next five in the next seven and so on. Now that is absolutely concrete you can imagine Galileo there in Padua doing those experiments and the water coming out of the tank. That is concrete. That’s the way students should be taught.

[00:59:56]  Green: Nothing like what high school physics is like and yeah. Yeah, they don’t even get to know much they studied in a very different way but. So, just to kind of one more thing about it so that friction like term with that dictate a slightly different path in shape dynamics then or how to think of that then.

[01:00:16]  Red: No, no, it’s, it’s just, it’s just a very characteristic way of saying how the shapes evolve in reality.

[01:00:28]  Green: Okay,

[01:00:29]  Red: and that’s really how reality changes. Certainly if the universe is a self contained dynamical system it is actually, it is what David does with that paper. And, and I think we also did it in a slightly different way but in essence it’s the same thing. We actually say this is what the universe really is doing. We are just absolutely pinpointing exactly what the university. Of course this is the classical universe described by classical dynamics not. We’re not talking here about quantum mechanics at all that’s that’s a whole new thing you have to contend with as well.

[01:01:08]  Blue: And

[01:01:08]  Green: then, with this way of looking at things so when we look at say the cosmological redshift when we see the redshift of the galaxies which are attributed to the expansion of the universe. Would it be correct to say that then we interpret them as the change the shapes changing or how do you interpret the cosmological redshift. Ah,

[01:01:29]  Red: well, first of all, the observation is in terms of shapes. So basically, the, what the observation of a redshift is is the following you have in a laboratory on the earth. Where was done. You have atoms which emit radiation and they, they, that radiation is going through a laboratory, or it might even be at the telescope up in the telescope. And, and there are, there’s a wave there, and it has a wavelength, and it’s literally there in Mount Wilson or Mount Palomar. There it is. Well, now it’s in these fabulous observatories in Hawaii, and then in Peru and the Atacama Desert and so forth. So, there is the. So first of all, you have a source, you can imagine you should think of it this way. There’s a source there with atoms that are generating waves of a certain wavelength in that in the observatory you can have it. And then there’s also light coming from distant galaxies, and that too has a wavelength, it’s come from the same atoms, and you actually see them going next to each other. And the one that’s come from the galaxy, it may have left the galaxy an awful long time ago, but the radiation you’re looking at is here is there in the observatory next to the one that’s been generated by the atoms in the observatory, and they have a different wavelength, and it’s all now here. And that’s all you can say that is part of the shape of the universe at that instant at which the observation is being made.

[01:03:16]  Red: And if you’d made the observation would come out the ratio of the wavelengths would come out differently at different times if, if there were telescopes back much closer to that galaxy that admitted the things in the time. The ratio of the wavelengths would have been different. If that had been made, you know, two billion years ago, if it could have been made two billion years ago, and maybe it was maybe there were planets with with astronomers doing those things. But it’s all the observations, the facts are all shapes now in the now. And that’s, and it’s in that sense that we say the shape of the universe is changing. It’s not, it’s not so much really expanding as as its shape is changing.

[01:04:06]  Green: All right, thank you for clarifying that. Maybe Bruce I know you wanted to ask some questions related to thermodynamics. Yeah, maybe I’ll let you do this.

[01:04:15]  Blue: Actually, let me ask, what about you, you just said you stated that very clearly that it’s not so much that the universe is expanding as shape is changing. That like is mind blowing for me I’ve never heard that before I started becoming introduced to your work through Saudi. But what does that mean like is the universe literally not expanding. Can you help me kind of understand the difference between the shape changing and it versus back you know imagine expanding very easily is what I’m trying to say. Whereas I can’t quite get into my head what it would mean to not be expanding, but its shape is changing.

[01:04:48]  Red: Well, that’s, I should say that this this business is is is still, I would say it’s still very mysterious. I mean, there is, there is one sense in which you can say that the universe is expanding. And it, it, it, it, well, it does show up in those in how the shapes change. It’s, let me remind you of the know, I don’t know whether this will help, but there’s a, do you know what you know what a geodesic is, Bruce. I’ve heard the term but not really. Well, so, if you imagine walking in a hilly landscape. And you want to get from a to B. I think you can intuitively grasp the idea that there’s a shortest distance between the two points.

[01:05:42]  Unknown: Yes. Yes.

[01:05:42]  Red: Okay, that’s a that’s a geodesic. Okay. Now, if you and, and how would you. And if if there is a if there’s a law which determines geodesics which there is on the surface of the earth. The geodesic is determined if you go to anywhere on that surface, and then you look in a certain direction, then that defines a geodesic from then on you don’t have to specify anything more than just the initial point and the initial direction. And in a in in two dimensions, the initial point requires two numbers and the initial direction requires only one because you only have to say it’s it’s one. It’s an angle between zero and 360. Sure. Now, what is very, very mysterious, I think, about the expansion of the universe, when you look at it in shape space, although the universe is only at any instant has a shape and that shape is changing. When you want to describe it, you ask, can I describe it, can I describe the change of those shapes as if the universe was following a geodesic as it’s changing its shape. The answer is no, you need one more number. And that number is really what the, it’s really what the cosmologists think of as the rate of expansion of the universe. I see. Okay. And so that I’m not so and in some senses, it’s perfectly all right for the, I did say that earlier when I was talking about how the students are introduced to cosmology. The, the facts in cosmology do give real sense really to saying that the universe now is twice as large as it was at some earlier epoch.

[01:07:41]  Red: That’s, that’s a meaningful statement, but it’s in both cases, it’s extracted from the way the shape of the universe has changed between the two things. The information is in the two shapes at the beginning and the end of that period. In other words, you’re

[01:07:58]  Green: saying that in that sense of looking at things one size is almost treated as a little bit more physical or absolute and everything else has increased relative to that. Is that I

[01:08:10]  Red: didn’t quite, I didn’t quite catch the start of your question, so could you say

[01:08:14]  Green: so in the standard way of doing cosmology one would think as if one of the size like you’re saying you know you’re comparing the size of the universe to some size that you’ve already taken for granted, as in some sense absolute, whereas in shape dynamics all that matters are the ratios so that question becomes kind of meaningless, because

[01:08:34]  Red: well, it, it, I would say it’s put in a different perspective and from my point of view it highlights a real what I increasingly think is really the great mystery in cosmology and perhaps in physics that you, and this goes back to what I was talking about a geodesic law so the, if you really, if you really want to, so the great ideal of a theoretical physicist is to find a law that is more predictive is the most you want to you want the simplest most predictive law that you can have, and if we’re talking about a law in shape space that governs how shapes change, you would want it to be a geodesic law where a point in a direction determines the law, and that is just that is just not the way the universe works you need one more number so it’s basically you could so what the I can tell you what the universe is really doing in terms of my geodesic story so I got you you’ve got this clear picture of going along it on a on a hilly landscape between two points along a geodesic and what the universe is is doing as its shape is changing it’s not going along that geodesic, but this constantly something which is tugging it away from the geodesic it doesn’t exactly follow the geodesic. It gets tugged away from it all the time so it’s turning and turning, and it’s, it’s always being driven to a particular point where, where this particular points where the, where our complexity or the Newton shape potential that thing is, is, is, is higher it’s dragged towards this point so it looks in shape space it does look like the effect of friction.

[01:10:36]  Red: And that’s what David Sloan’s talk and paper is about and it that’s that’s the way to think about it. And this I think is very, very mysterious because when Newton introduced absolute space and time, he introduced position that’s that was never a real thing because of Galilean invariance so the famous fact that you can’t that uniform motion can’t be detected within a system I mean we don’t feel the earth moving. So that, although that appears in Newton’s picture of absolute space, it’s it’s not it doesn’t have any physical effect, but orientation does rotation is possible so that that’s there. And energy absolute time has an effect because you can have different energies so you can get rid of those and they disappear from Einstein’s theory in, in, in, in, in a sensible model of that and they disappear in in a much in point of view. But the one thing what also Newton introduced was a notion of absolute scale as if there was an absolute as if there was a ruler outside the universe, right, and that’s what seems it that’s one way of interpreting what the universe is doing, I prefer to think of it as this thing that is tugging you away from a geodesic. But that’s, that’s, that’s the objective way of saying what the universe is doing, there is something which is tugging its curve in shape space away from the instantaneous geodesic that it could be following. And that’s, you can say that’s the effect of absolute scale that Newton brought in.

[01:12:39]  Red: And I think what on earth is going on there, why is that there, I would say that is the, for me, at the level of classical physics and it may be intimately related to what’s going on in quantum theory. That is the great mystery. And I think this is the value of this is what shape dynamics has done is it has pinpointed this one fact I think it is just the great mystery. Interesting.

[01:13:10]  Green: Could that have something to do with dark energy by any chance. I was

[01:13:14]  Blue: about to ask that. That’s I don’t think

[01:13:19]  Green: it’s almost like saying, oh, there’s something that we just don’t know about that’s where we just, you know, it’s

[01:13:26]  Red: I don’t think I certainly don’t think it’s anything I would be very I don’t think it’s anything to do with dark matter. So dark matter makes up about a quarter of the mass in the universe. And I, I share, I mean, I’m not an expert in these things but I think the evidence from astronomy cosmology is that there really is some dark matter there that they just haven’t yet managed to pin down. But dark energy, I would say I don’t want to. I think I think maybe one, if shape dynamics is does if show dynamics is the right way to go. I think it may say something about dark energy and also the very early universe when, when modern cosmology invokes something called inflation, I think shape dynamics has the potential to say something about that. And I’ve, I’ve written about that. Not so much about dark energy but about inflation in my book the Janus point which came out well nearly a year ago now.

[01:14:32]  Blue: All right. Let me ask a couple of my other questions here I was watching an interview that you did I can’t remember which one. And you were talking about how at the point of the Big Bang is the point of the least. But the universe was it’s most boring it was the most similar and then going out both directions from there, only one of which would be able to see, you would see increasing in numbers of complexity from that big bang point I explained that correctly is that that what I

[01:15:02]  Red: that’s that’s more or less right. I can’t remember that there are two options that I discuss actually in my book and in some senses the title of the book the Janus point applies to one of them, which I now think is the less interesting but it’s still, it is still very interesting because it looks to me as if it could say that there is actually no real, ultimately there won’t be any mystery about why see why time seems to go in one direction so but in that model, the universe is at its is at its most uniform at a central point on so to speak the timeline of the whole universe and in either direction away from that central point which I call the Janus point. And the universe gets more clustered more structured, and that is basically the dominant thing which is determining the direction of time, and that matches exactly what what the universe does seem to have done since the Big Bang. It’s clearly very soon after Big Bang, at least it was very uniform, and it’s got more and more clustered and structured ever since. But there is another possibility in Newtonian theory that there’s not two sides of the Janus point but so to speak that the universe starts from zero size now that such solutions exist in Newtonian theory has been known for about 130 years. In fact, so it, there are solutions in Newtonian theory where the, where the particles are sort of doing their thing, and then somehow or other they seem to conspire or they’re sort of set up in a very fine tuned way, where actually they come together and they all collide

[01:16:51]  Red: instantaneously at their common center of mass and that’s called a total collision, and that such solutions exist within Newton’s theory was, as I say discovered about 130 years ago there was a very fine paper by a Frenchman called Jean Chassie which spelled out all the details in 1918, 11 years before the expansion of the universe was discovered. Now, if you reverse the direction of time, which you can do because the Newtonian equations don’t distinguish the direction of time, then that type of solution becomes a total explosion it is a Newtonian Big Bang. And what is very interesting about those solutions is that the shape is very special, it’s what’s called a central configuration, it’s a very interesting shape. And, and in fact, there’s just one of them, where the shape is more uniform than any other possible shape can be, as measured by this quantity we call complexity, which is simultaneously the Newton gravitational potential made scale invariant. And in my book the Janus point I call that alpha. And in that case you would have a model of a universe which starts not exactly uniform because it can’t be perfectly uniform according to the formula, but it can be as it’s nothing. In accordance with the formula, no distribution of the points can be more uniform than that. And then, and when you actually look at what they look like they’re incredibly uniform they, they, they, if you have that they’ve been calculated for up to a few thousand points and they’re actually all concentrated in a perfect sphere with very uniform density and then

[01:18:40]  Red: there’s just an abrupt edge to the sphere but it’s, it’s the separations between the particles and not exactly equal there’s just ever so slight variations within the separation so I think that might be a Newtonian model for what the Big Bang was like and that I think it’s just possible that inflation which is quite a successful theory but they have quite difficult in explaining why it should start and there are some issues I think without answer. It might replace it so I think, I mean then, if we, if we could really show that something like that is also what is really happening in general relativity at the Big Bang, about which there’s a lot of uncertainty, then shape dynamics would really have triumphed. But that’s, that’s sort of for tomorrow.

[01:19:32]  Green: I was also wondering if you could, since we’re talking about that like how the arrow of time, the asymmetry kind of emerges out of that then. So we are looking at a very kind of uniform type of configuration. How would we look at the asymmetry that we associate with time, the arrow of time.

[01:19:55]  Red: Well, the, just briefly about the history so ever since the laws of thermodynamics were discovered and the notion of entry was discovered. Physicists have all believed that there’s what’s called an arrow of time and they think the most important one is the entropic arrow of time and that says that the, if it’s applied to the whole universe which virtually everybody does do that says that the universe must have started off rather ordered and to be the disorder entropy as a measure of disorder in the normal interpretation and it’s increasing and then Richard Feynman was one of the first people in fact he may be in the first person who said it really clearly. There must, you can’t explain this, the universe must have started with a low entropy but there’s nothing in the laws of known laws of nature, which would explain that that would be the case. So that’s that’s that got called the past hypothesis by the philosopher of science David Albert. And it’s been, it’s been a great mystery. All that it was a great mystery became clear in with the work of Boltzmann in the 1890s in a famous debate he had with somebody called Dan Zermalo. And so that’s that that’s great mystery but what we what we showed in in and in fact actually we were just exploiting things that have been known for 200 years in Newtonian theory in Newtonian theory. All you require is the energy to be non zero and in a much interior you would want it to be exactly zero.

[01:21:42]  Red: And then you will always have these Janus type solutions where at one point on just one unique point on the on the world line of the universe in the conventional Newtonian sense the size of the universe is is minimal. But in the way we think about it the uniform is more uniform than in either direction from that point. And then the universe gets more clustered in both directions away from that point we intelligent beings must be on one side or the other of the Janus point. And they will see laws which seemed not to respect to not to have a direction of time that the time could flow in either direction, but everything around them is going in one direction the universe is getting more clustered so the, the main significance of that paper from the 2015 is to show that there may not be any mystery at all you don’t have to add anything on to the existing laws which was what Feynman said, and it just comes straight out of Newton’s law. And if it comes out of the oldest dynamical law in the history of dynamics, it may well come out of everything else in dynamics now we haven’t yet shown that but I think there’s a distinct possibilities that the case so that’s that’s the significance of there. Now the interesting thing is the same, you can have these very special solutions, which I think, because in general relativity, characteristically the size of the universe does go to zero or it all comes to a point in the normal way they describe it.

[01:23:22]  Red: I think that Newtonian model where the, which starts with the total explosion might be a good one and in which case it starts the universe starts, not exactly uniform but as uniform as it possibly can be with just it’s born with a few wrinkles. And then they just get bigger and bigger as time goes on. And maybe we the arrow of time is, it could be, you know, completely explained.

[01:23:48]  Green: So let me ask you a question on that. Can I ask a question

[01:23:52]  Blue: quickly on that one.

[01:23:53]  Green: Yeah,

[01:23:53]  Blue: with the people on the other side of the Janus point would they be for all intensive purposes in a different universe.

[01:23:58]  Red: Yes, because you couldn’t communicate and they would have the sense of time going forward and exactly the same as the ones on this side. Right, but I mean so I’m increasingly getting more attracted to this model where there isn’t a Janus point, but the same effect really comes for anybody in the universe. But with the added bonus that if if these ideas is right then we explain why the universe started in such an incredibly uniform way. Okay, go

[01:24:29]  Blue: ahead, Saudi. So

[01:24:31]  Green: I was thinking about the arrow like what would be the reason to think that the arrow is pointing away and not towards the Janus point is that to do with what we see when we look at the cosmic microwave background. Well

[01:24:44]  Red: that’s that’s a question of bringing in the other arrows of time so and you could think about this in terms of what you call gradient so the, you can say, you can say this, if you, if you say that increasing clustering is like going up a hill then you’ve got a gradient going up hill. Okay, so that’s one arrow of time but there are other arrows of time, like our memories. We remember the past we accumulate more memories. So you could put a gradient there of the number of memories we have. And there’s the, there’s the collapse of the wave function and there’s the increase of entropy and things like that. So, the question is, what would justify us in saying that the, that the, the gradient defined by the clustering the increase in the clustering is, is the same as all the other arrows of time the one to do with us forming memories and when you can talk about entropy properly that that should go in the same direction. Well, once in this model of the universe we have we pointed this out in a later paper than the one that we published in 2015. No, actually, I would cure I get it wrong. The one in physical review letters was in 2014 2015 we pointed out that in such a universe, if subsystems form, they will have negative energy, and as they form they start to behave in the normal way with as in terms of dynamics, and you would have something like an entropic arrow within the subsystems, and that entropic arrow within the subsystems would point in the same direction as the overall clustering in the universe at large.

[01:26:44]  Red: And I don’t think anybody really doubts that the way we accumulate arrows also agrees with the direction in which entropy increases all. So, I think that’s the reason why you would say that’s, that’s the sensible way to define the direction of time by itself your right side you could say just the clustering by itself you could say the arrow is pointing to or away from the Janus point or two or away from the beginning of time. But once you add in the other ones if you’ve got a theory for the other ones and we certainly have at least the reasonably good outline of a theory of the entropic arrow. I think we, you know that settles in.

[01:27:30]  Blue: So, in that same interview, you mentioned that as things move away from the Janus point or whatever we’re calling that complexity increases and you even went so far to say that this seems like a sort of teleology. Well,

[01:27:45]  Red: now we’re getting, you know, when people reach my age, I fell into my ages. People say now they get senile and get sort of carried away with crazy ideas. I have to say I begin to wonder. And I have been greatly influenced, like my friend Lee Smolin by Leibniz I introduced Lee to Leibniz. Now Leibniz is a very fascinating thinker the great logician girdle with his famous girdle theorem was a great admirer of Leibniz. So Leibniz talks about perfection of laws and perfection of the universe. Well, I already mentioned that the ideal of a theoretical physicist is to is to is to find a theory which is is perfect and more predictive than any other theory so Leibniz was sort of advocating creating things like that. And he, if you read Leibniz and he’s I do recommend that he’s very, he’s very thought provoking. A basic point that Leibniz makes really is that if there were no variety in the world, you couldn’t say anything I mean you couldn’t begin a completely uniform universe has no meaning it’s just a blank there’s literally nothing there. Yeah. So Leibniz has this idea of perfection, which is to make complete or to progressively make more complete more perfect. And so that suggests that a universe which starts off with very little variety would get more interesting it would get more perfect if the variety increases. And in fact he argued very late in his life in his famous monodology. Very much along the lines which I did earlier about structure could go on right down infinitely deep forever you know you could keep on looking with microscopes and in the monodology has a very famous passage where he talks about.

[01:29:55]  Red: He was very influenced by the, the Dutchman Lervenhoek’s microscopic observations for these incredible microbes that he discovered with his microscope and I described and Leibniz was hugely impressed by this and he argued that the every living tissue has more living tissue within it and he talks about every pond has fishes in it and every fishes within fishes you could find ponds with with fishes within those ponds, all the way down. I mean like the rhyme about fleas upon their backs to bite them and they have a lesser fleas and so on, add in for an item. And that idea of Leibniz was killed when quantum mechanics was discovered because quantum mechanics really puts a lower limit at the present stage at the present stage of the universe so what’s rather interesting about the universe I find is it does seem to have started very uniform with very little variety and certainly the variety has been increasing very impressively up to the present epoch. But there seems to be that idea of Leibniz is ponds within ponds and fishes within fishes and fish ponds within fish ponds all the way down. That’s not right, but I don’t think it’s entirely impossible that in that the universe could go on that so to speak there would be increasing levels of ponds within ponds. This is at the stage where some professional physicists who happen to by chance to listen to this will say, ah, yes, there’s true. He’s just naive or, you know, he’s a hopeless optimist. I mean, Leibniz was made fun of by Voltaire in Kondid as pan gloss. So, so that you could dismiss me as being pan glossy and but

[01:32:01]  Green: let me ask you one thing on this. So if there is a unity to the universe that type of geometric energy we’re talking about, wouldn’t that mean that identity like that would give a very precise meaning to identity, because each view would be unique which means that we may not really have pond within pond but maybe other stuff within kind of like the infinity we were talking about but just the infinity in diversity and not as the sort of thing that cosmologists sometimes talk about that where they may be repeating parts of the universe where we’re doing exactly what we’re doing right here but somewhere else.

[01:32:41]  Red: Yes, these are all metaverse ideas. I have to say I’m skeptical about the metaverse because well first of all it. My understanding is it requires an infinite universe and and it’s all within one space time and it all assumes this external scale. I’m, I’m skeptical about it. And it, it came out of these ideas came out of eternal inflation it came out of the success of inflation so cosmologists who developed inflation said well if it could happen once it can go on happening again. And then before you know that they’ve got these things, but then they get into terrible probability difficulties with trying to make any predictions about the multiverse. Lee Smolin is written very effectively about this and serve other people. So I, I put more faith in there being just one universe. And then it is very Leibnizian that you could look I mean Leibniz says that monads and he identifies us with monads he says we are just views of the universe from a particular point of view. And I think, I think that’s that that’s quite an idea. What I’m now suggesting is conceivably those views. In some senses could be infinitely rich, perhaps, perhaps in the distant future there are centers of consciousness, I mean we know, we know, we know so little about consciousness and we understand it. Understanding of consciousness is pretty limited. You know, maybe there are richer things in the future. Who can who can say. So,

[01:34:39]  Blue: let me just a moment ago you mentioned that quantum mechanics at least at this stage of the universe puts a limit on a lower bound limit on sizes. Are you suggesting that as complexity increases that that could change at some future point in time.

[01:34:57]  Red: I think it’s, I think it’s possible. It’s, it’s, I mean, there’s, there’s no doubt in my mind, the amount of variety in the universe can just go on growing and growing and growing. And, and in some senses, it can, it can be measured I mean it in the simple model we have with point particles we have complexity which which measures how much it is. Now, there is an interesting possibility that my collaborator Tim Koslovsky came up with. So, basically, our Newtonian models have, as we developed it just have a fixed number of particles I mentioned that before the number of particles is fixed. And then, then, then any shape that the particles come in any distribution, which defines the shape that has a given complexity. Now, but that complexity depends changes, you can have a larger complexity the complexity depends upon the number of particles and the way they are arranged relative to each other. So you could imagine a universe in which, first of all, the complexity literally is time that that that what we call time is just the universe becoming more complex and literally is a pure number defined by the value of the complexity. And then that could increase also by more particles coming into existence you would have genuine creation of particles as well as them being able to move into different positions relative to each other. And in that way, the complexity could go on growing forever and there would be, you know, more, there would be creation forever. I don’t know, I mean, this is, as I say, I’m sure there were if, if some professional theorists get to listen to this they might be shaking their heads and say, sure that man. But it’s not impossible.

[01:37:06]  Red: But to be honest with you, Julian, I think if anybody in their own time isn’t really kind of letting their fancy kind of go wild here and there, then I don’t know if they’re not being creative.

[01:37:17]  Green: I think I think we should as long as you know your papers are to the point so.

[01:37:22]  Blue: So actually related to that so first of all, would that mean, in essence that the plank that the plank length can change over time.

[01:37:29]  Red: Well, the way I think was that all the plank length changes compared with standard cosmology the plank length changes relative to the size of the universe so the site the normal size of the universe that that is the cosmology that we’re going to talk about is the Hubble radius. And very early very soon after the Big Bang, the plank length was was not much different from the Hubble radius now it’s a tiny fraction of it I don’t just guessing it is it one part in 10 to the 60 or something it’s a tiny fraction of the Hubble radius now. So, to say that the plank constant is not really a constant because it’s it’s a constant relative to the things that are used to determine it and basically that’s the cesium atom, but instead of the cesium atom, you could think about cosmological scale so it’s there’s nothing inconsistent in what I’m saying and in fact, I would say that the inverse of the of our complexity, you could call that a dimensionless plank length, and that will change it will be different in different in different for different shapes of the universe. And that’s no different from the present situation when you say, what’s the ratio of the plank length to the Hubble length that is changing that’s getting smaller all the time in standard cosmology so there’s there’s nothing particularly untoward in what I’m saying there.

[01:39:11]  Blue: Okay, now, going back to teleology, though, I realize that’s kind of a dirty word to a lot of people in science, but in evolution, it’s not like I can easily talk about a heart having a purpose is to pump blood, because of its evolutionary setting invoking a sort of teleology in evolution at least in a certain way is considered acceptable as long as it’s consistent with like neo Darwinian evolution. What would be the equivalent for physics though like we’ve got this complexity increasing over time. Where does that come from what is the complexity come from. Is there something equivalent to evolution that allows us to invoke teleology without violating anything or is this just a mystery at this point.

[01:39:54]  Red: Yeah, well, first of all, I think quite a lot of biologists would be quite cautious and saying that evolution is teleological. I mean, there is this thing that I think the human brain now is 10 % smaller than it in for the Neanderthals and that’s just because we’ve got much more efficient at getting food. So we don’t have to have such big brains to know where all the food sources are or things like that. So, I mean, evolution doesn’t necessarily always go in the same direction but that that that’s a minor issue. Yeah,

[01:40:35]  Blue: it’s, it’s what I’m not suggesting that evolution itself is teleological, but within evolution you can invoke certain kinds of theology by the existence of evolution evolution. I think

[01:40:48]  Red: the,

[01:40:50]  Unknown: in

[01:40:50]  Red: the sense that you say that organisms will evolve to suit the niche in which they find themselves there. That is the best explanation of functionalism sort of. So, but I mean now we’re getting I mean, at the moment I’m having very interesting discussions with with three people one is one is somebody who’s who was in finance and has now gone back to study because he’s decided in midlife that he wants to really think about the universe again and then I’m talking as well to a couple of physics students they’re both in their fourth year. One is in Iran and the other is in India, and we’re looking at Leibniz and I must say he’s very interesting he makes all sorts of suggestions and in Leibniz’s time, I mean metaphysics was not a dirty word. One one one looked for deeper reasons for why things are the way they are. And it’s only comparatively recently in in, I mean I don’t know when in the since the scientific revolution that came in was basically with Newton. When scientists started to say science cannot answer why questions, it can only answer how questions.

[01:42:23]  Unknown: So,

[01:42:24]  Red: if you have a, if you have a law, it can then tell you what the consequences of that law are but it can’t tell you why that law is there why the law is there. But Leibniz is constantly arguing about that law and he does what possible laws that could be and what the universe could be like, and very often the criteria he comes up for are the sort of ones, and I’ve already hinted that the theoretical physicist’s love, which is the search for the theory of everything that the big toe the great, you know, the theory of everything. That’s a very Leibnizian metaphysical principle. It’s, if a theoretical physicist is listening to this now he’d say, oh yeah but it’s justified because first Maxwell unified electricity and magnetism then Einstein unified inertia and gravity, and then more recently particle physicists got a long way with unifying the forces. That’s fine, but the what’s driving them on to get it even better is still nevertheless that Leibniz in ideal for the perfect theory so in a way Leibniz would say perfection is a metaphysical principle. So.

[01:43:51]  Green: But let me ask you doing about this so in that sense aren’t we kind of talking more sort of like a meta law which is taking us a little bit beyond relationalism then.

[01:44:02]  Red: Well, we, we may but Leibniz is is, I think Leibniz would I mean I said early on I some I’m sure some years ago, well it’s about 40 years ago, I read that Leibniz reserved. He wrote very little in German but but apparently he, what I read was that he’s, he expressed his deepest thoughts in German. And in one of his German writings he says that variety is reality. That is what reality is. And that very notion, if that’s what he said and I keep on trying to. I mean to try and search for that my every time I meet a Leibniz in expert and I say is that what he said and they said yes he did say that and then I said can you send me the reference please but I never get it. But it makes perfect sense from, I mean everything I’ve read of Leibniz that makes perfect sense that that variety is reality, and then perfection will mean perfection the etymology of perfection is to make complete a path is thorough through to go through something perfectly and and effect is is from far too great to make so it’s to make something perfect to to to. And so the idea that the ideal law of the universe would be to increase variety forever is, is not unreasonable and it does come out of Leibniz way of thinking and certainly I’m finding it very stimulating. Discussing it with these people and the three of them really a very interesting. And I mean at least the, the, the one from Iran is very knowledgeable about philosophy and he’s very sharp comes up with very interesting comments.

[01:46:03]  Red: So, I’m, I’m getting a little less worried about coming up with a little bit of metaphysics but but making clear what the idea is, and one has got to have some stimulus to look for a law. And my goodness me the universe is, is time of the fascinating when you think about consciousness and all these issues maybe we do have to think a little bit out of the box.

[01:46:32]  Green: I agree with you because to be honest with you when I look at the world around me, I, I feel like this sounds like a pretty reasonable thing to say. I mean, I think what happens is a lot of times physicists from within the view that they’ve held what’s worked for physics, well when we’re studying very simplistic systems, somehow they tend to kind of generalize that to the whole of reality but it seems like at least when we study biology complex system. It does seem to me that that is best explained in some form of functionalism and there has been an increase in complex complexity. The world seems to have gotten more interesting,

[01:47:13]  Blue: but you mentioned reading Leibniz, do you have a recommendation like as a starting point for learning some of his ideas that you’re referring to here.

[01:47:23]  Red: Well, the book that I’ve got two books. One is just called Leibniz philosophical writings and it’s published by it’s called every man’s university library of Leibniz things I bought it back in nine, edited by somebody called Parkinson and this was published in 1973. The I mean, I mean the book is the book is incredibly rich it’s only actually all of the ones that the ones that you read that you see cited and a lot. It all comes in quite a slim volume it’s it’s it’s just over 220 pages and you can dip into them. Leibniz is not always easy to read because he started off very much with scholastic medieval philosophy which he’d never entirely shook off so it’s quite difficult to to get into what he’s really driving at. So it does help to have a bit of an introduction but I mean he talks about simple substances and you think that’s just like a pat of butter far from it. It means something that’s got all sorts of relationships within it which holding up knitting it together to use my expression it’s something which is knit together by its that its attributes sort of all hold it together. But if you, I don’t know whether I’ve, I’ve never actually. I mean Bertrand Russell wrote a book about Leibniz philosophy. I, I read it many years ago. I mean I started reading Leibniz. It’s now back in 1977 so it’s about 45 years ago, and it made a huge impression on me without sort of clarification of exactly what he meant but there are things but I would say just get that then there’s a bigger collection edited by somebody called Lumka, L -L -E -M -K -E -R, and

[01:49:35]  Red: having the extra I mean there’s a huge project going on in Hanover to publish everything of his. A few years ago they reached volume 50 each volume about 800 pages that sort of with notes and letters that were sent to Leibniz. And they were only half they were only halfway through the project I mean it’s colossal unbelievable what he generated. And of course he was a very great mathematician he was joint discoverer of the calculus with when Newton he proposed the use of binary numbers created the first calculating machine. He’s a very, very remarkable person.

[01:50:18]  Blue: Yeah, sounds like he’s had a lot of interesting contributions. Okay, thank you. I will look up some of those books and now I’m very curious. Yeah

[01:50:27]  Red: Parkinson make a note of the name Parkinson like like the unfortunate neurological disease. See if you can find it’s the book I’ve got is called live this is philosophical writings I guess I it’s still in print and if not you could get it in a library and I don’t.

[01:50:47]  Blue: 800. Oh that’s the master okay there are you versions you can get. All right, good. That’s probably that’s that’s probably the hardback or something. Yeah.

[01:51:00]  Red: I’m quite intrigued that my first book, which came out as a hardback is absolute or relative motion if you try and buy that on Amazon. It’s around $900.

[01:51:14]  Green: I must say I highly recommend that book like that that is that’s a beautiful book to me.

[01:51:20]  Red: In a way that’s the one that gave me more satisfaction than any other particularly what I really loved was was discovering what Kepler had really done it’s a phenomenal achievement that Kepler had. And that’s actually by the way which gives me so confidence in saying that it’s geometry that holds the world together because Kepler really was the first person who in his mind, I could travel in in space and imagine that he could go anywhere. He, I mean he was, he was always sort of saying, what will the you what will the solar system look like if I were on Mars when from the earth Mars is in such a direction relative to the fixed stars. Then I’m going to imagine myself. I’m going to then know if I get if I were on Mars, I would know what where I would see the earth from against the background of the stars that way. And then he then could use that to check various conjectures. It’s just phenomenal. He did that. And he also wrote one of the very first science fiction novels, novels, which is an imagined journey to the moon.

[01:52:39]  Blue: Well, we’re quite a bit over time so we probably ought to wrap up and it’s about it’s about

[01:52:45]  Red: time for me to stop making my supper. Yes. Anyway, but anyway, good to talk to you guys. Yeah,

[01:52:51]  Green: good to talk to you, Julian. Thank you so much for your time. This was such a treat. It

[01:52:55]  Blue: was. It was awesome.

[01:52:58]  Red: Well, it was a pleasure. Okay. Bye then.

[01:53:02]  Blue: All right, bye bye. The theory of anything podcast could use your help. We have a small but loyal audience and we’d like to get the word out about the podcast to others so others can enjoy it as well. To the best of our knowledge, we’re the only podcast that covers all four strands of David Deutch’s philosophy as well as other interesting subjects. If you’re enjoying this podcast, please give us a five star rating on Apple podcast. This can usually be done right inside your podcast player. Or you can Google the theory of anything podcast Apple or something like that. Some players have their own rating system and giving us a five star rating on any rating system would be helpful. If you enjoy a particular episode, please consider tweeting about us or linking to us on Facebook or other social media to help get the word out. If you are interested in financially supporting the podcast, we have two ways to do that. The first is via our podcast host site anchor. Just go to anchor.fm slash four dash strands f o u r dash s t r a n d s. There’s a support button available that allows you to do reoccurring donations. If you want to make a one time donation, go to our blog, which is for strands.org. There is a donation button there that uses PayPal. Thank you.

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