Episode 27: Chiara Marletto and Constructor Theory
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Transcript
[00:00:07] Blue: Welcome to the theory of anything podcast. We are very excited. We have Chiara Marletto with us today and we have an interview plan with her. Plus we have everybody else we’ve got cameo Tracy and Saudi here everybody say hello.
[00:00:21] Red: Hi, hello. Hi everyone. Nice to be here.
[00:00:26] Blue: All right, I think I’m going to get just straight into it so we can utilize time here. But, Chiara, how did you get involved with David Deutch’s constructor theory.
[00:00:35] Red: So I was PhD student in Oxford at the time. So it was 2011. And at the time I was looking for understanding this idea that von Neumann had about constructors that are these generalized programmable machines that can emulate features of living systems. And the way I landed on that is that I was interested in quantum biology. So I kind of my initial goal in in PhD was to try to figure out how to apply some of these ideas from quantum information to the realm of biology and specifically understanding some of these features that self reproducing entities like bacteria have and whether they can use quantum effects to, you know, speed up the functionalities, etc. And somehow, you know, as I was starting I was sort of digging into this work that von Neumann produced. This was something that he did in the 50s. I just stumbled upon this nice talk that David gave at the Clarendon laboratory, which is the part of the physics department about constructor theory. And I thought, hey, you know, there’s someone who is actually working on an extension of the ideas that von Neumann had. And then I realized actually this was much more powerful than von Neumann’s original ideas. And so I got hooked and I ended up basically working full time on that during my PhD, and then later on also developing it on my own in various directions. So that’s how it happened.
[00:02:20] Blue: Do bacteria use quantum effects for information? Do you know? Oh
[00:02:25] Red: yeah, I think, well, I mean, there’s a trivial sense in which they do. So of course, we, you know, the bacteria just work according to, of course, the laws of quantum theory, so in some sense all physical systems in this universe obey the laws of quantum theory. But then there is this other deeper sense that has fascinated both theoretical physicists and biologists in equal measure in a sense of whether natural selection has come up with methods to exploit quantum effects a bit like quantum computers do to sort of speed up some functionalities. And there are some theories about, for example, photosynthetic bacteria. So these are bacteria that live on the bottom of the sea. So they receive very few photons. So they need to really maximize the efficiency of conversion of the photon energy into chemical energy for their own things. And there are theories that kind of suggest that they might be actually using quantum speed up like effects. And these theories are at the moment are not fully confirmed. So I think in a way they are conjectures. We haven’t had, you know, it’s hard to make experiments because it’s hard to test the systems are very messy. But I think this is like what motivated quantum biology, which is like an existing field.
[00:03:50] Blue: Okay, that makes sense. I guess I had heard that there was some theorization around photosynthesis and quantum effects. Okay, yes. Now, in your book, you say wouldn’t it be wonderful if it were possible to take inspiration from these principles which relate to counterfactuals and imagine an entirely different way to formulate the laws of physics one that takes counterfactuals as primitives and the laws of motion initial conditions as derivative. Now, this is something that caught my attention, although this is something that David Dwayche and his first paper says something somewhat similar. And I’ve always been a little confused by it. And so I wanted to ask about this. The, the issue that I’m don’t think I understand is, why would it be it seems like constructor theory would be a very valuable theory, just exactly the way it is, even if it didn’t turn out that the the laws of motion initial conditions were derivative of it. What is motivating the desire to see it as underpinning all of physics rather than being something new that gets added into physics and expands the way we think of physics. I really like this question because it touches on on on attention, which is actually at the heart of this program in a way.
[00:05:07] Red: And so the tension is exactly what you do. You know, the thing that you just mentioned that on the one hand, you couldn’t think of construct the theory of the program of adding principles that based on counterfactuals to the existing laws of physics as a as a kind of supplement of existing physics in a way that it gives us more tools to, you know, describe the universe and that’s you know, doesn’t need to represent anything more fundamental than say dynamical laws themselves, it could just be something that you add on the side which help, you know, which can help understanding things better. But then, and I think this is actually the vision that David had when he wrote his sort of initial seminar paper where he kind of outlined the whole philosophy of the approach. The hope is that not only will this new approach at methodologies that are helpful to understand things better, but it could also provide a deeper foundation for the existing laws. And that is necessary. That’s considered as necessary, at least in different to a different degree, but by both myself and David, because the dynamical law plus initial condition framework isn’t in itself very satisfactory as an explanation for lots of phenomena that exist in the universe and that should be actually included into physics but currently are not or are only imperfectly included, because the dynamical laws are not quite sufficient. And so, as always in physics is seems natural that when you find an explanatory tool that can dissolve or solve problems within an existing framework that framework becomes somehow derivative or secondary with respect to this new set of laws and tools that you have discovered.
[00:07:25] Red: And so that’s the second and more ambitious way of looking at constructed theory. We don’t know if it will succeed this kind of vision, but I think it’s, it’s, if it’s not constructed theories should be something else that provides a deeper explanatory framework for the dynamical laws that we currently know. And I think if it’s not constructed theory should be something else but there should be some additional stuff that we discover as being deeper and more fundamental than these laws that we are currently using.
[00:07:57] Blue: Okay, that makes sense. In the conclusion of David’s original paper he says the principles of constructor theory that I propose maybe faults. And then he goes on to say but if, if, if the idea is false then something else will have to remedy and then he lists out several the things that in your book, you show that constructor theory can remedy. Yeah. So I often wondered about what he meant there and I guess it’s what you’re saying that it may be false that it underpins all of physics, but it clearly has something true to it it’s already solved substantial problems in physics. Just from reading your book you go through several examples of that is that correct.
[00:08:37] Red: Yes, this is correct. I think the, so we have to be be careful here because there are lots of ideas that this question somehow brings into into focus. So, the first point to make is that so constructed theory is a set of, you know, he’s made of a set of principles and these principles are on the one hand, supposed to be new laws so they are, they add to the existing laws as we know them. They have continuity in terms of logic with some principles that exist in thermodynamics, such as the second law or the conservation of energy and so on. In the sense that they’re not formulated as dynamical equations, but they are formulated in these more general terms about constraints about counterfactuals what’s possible and what’s impossible. But they are new laws and in that sense, they as new laws may be false. So for example, it could be that the principle of interoperability of information which is one, one of these new principles that we proposed recently could, which basically kind of captures the idea that information can be copied from one system to another with no restrictions and so on. So this, this principle could be actually false in the form we proposed it. But the point is that the approach in itself, the fact that it’s kind of using counterfactuals as additional things that are necessary to explain features of the dynamical laws, etc, etc. And in a way it was already there to stay because it exists already as I said in, in thermodynamics. It was used largely also in the theory of quantum computation and information theory in general.
[00:10:32] Red: So, in a sense, what we are doing is a continuation of this sort of tradition just on a much broader scale. So I think that’s what David meant with that comment. Okay. On the other hand, the other stuff that you mentioned the new ideas that we proposed. Some of these new principles actually have consequences and these consequences appear to be directly testable. And therefore, as I said, it could be that they will be falsified at some point, they could be tweaked. But the hope is that this new approach with counterfactual will stay. And that’s the kind of vision behind constructive theory. Okay, makes sense.
[00:11:06] Green: Actually, let me ask one thing here. I was actually wondering that, like, would you say that determinism is basically assumed for constructive theory. But by that I mean like, you know how in the many worlds interpretation, it’s a pretty much deterministic view where it doesn’t really leave any room for saying that there are certain possibilities that just never actualize, but may just remain. And kind of, you know, that other approach might leave room for indeterminism. Would you say that the determinism is kind of assumed as a priory for constructive theory. I think not necessarily
[00:11:51] Red: in the sense that determinism is, it’s a nice, it’s very nice question I think the so constructed theory is doesn’t have dynamics as a kind of primitive thing right so the determinism is. It’s often at least most, you know, most formulations of what the terministic means require there to be some dynamical law that takes states into other states. And then one way of thinking about the terminism is that the said there’s no stochasticity involved in the laws a bit like as you said in the laws of quantum theory where stochastic evolution is is not really there. I mean this kind of Schrodinger equation which is deterministic and then you add on top some probabilistic stuff with the born rule and so on. But I think the so it’s in a way constructed theory in itself doesn’t require the terminism to be, you know, principle of nature or anything like that. However, when we, when you go particularly to things like the constructed theory of information for example where we lay out these principles that are needed for the kind of actions that are required for information to be physically possible. Then it’s, it’s implicit in some of these principles that it must be possible, one of the tasks that so one of the kinds of tasks that must be possible for information to be instantiated are one to one tasks so things that don’t destroy or create information out of nothing as it were.
[00:13:22] Green: And wouldn’t that I’m sorry to interject that but wouldn’t that imply that determinism. Yes,
[00:13:29] Red: so it would imply if you were to make a model. So if you if you so the concept of a task doesn’t necessarily map onto dynamical law directly but once you, you know, let’s say you want to make a model for what it means for a constructor to perform a task under a certain dynamical law, then for these principles to be true, then it seems like these dynamical laws should be deterministic in the sense that that you were envisaging so you could say it could be that there is a different constructors here where these principles are not true in which you know the regularity need for information in the universe, etc, etc. Then, yes, so when you want to transfer these principles into constraints on dynamical laws. This would suggest that the dynamical laws have to be deterministic.
[00:14:27] Green: So for example, let’s say that our universe actually there was some sort of an evolutionary principle whereby the universe is actually the laws are changing or maybe even new laws are being created. So that that means that the constructor theory should be able to handle because as long as laws are, you know, we can identify something as lawful. Yes,
[00:14:51] Red: yes, exactly. And again, these laws are not the primitive things so somehow they should be consequence of these more fundamental principles.
[00:14:59] Green: In a weird way, it’s almost like laws or something that is it turns out to be a useful way for us to talk about things, you know, yeah. Yeah, Karl
[00:15:07] Blue: Popper and his epistemology particularly in his book the logic of scientific discovery. He formulates his epistemology in terms of universal statements. So for those who aren’t familiar with logic a universal statement would be for all so for all swans color is white. That’s a false universal statement because we know that black swans exist. Therefore we can refute or falsify that universal statement. But universal statements, what really makes them useful is that they forbid things so that you are able to refute them. I couldn’t help but feel like there was an analogy there to construct your theory is that accidental coincidental or is constructor theory and an attempt to inject Karl Popper’s epistemology into physics.
[00:15:52] Red: That is a nice point. I think, well, in this sense, I think constructor theory is not at heart anymore. Popperian than other bits of physics is just that they are not explicit about it in some sense. So let me explain the so all those that traditional regard is as fundamental. So they are primitive or somehow they kind of they underlie everything there is in the universe. You know you can take different definitions for fundamental but broadly speaking I mean something like that. So all these laws have the feature that they forbid things in a in this in the kind of universal fashion so and then and then sorry on top of this I think to falsify them. You have to go along the kind of pop process that Popper envisaged. So in this sense I think, you know, the way in which you would falsify a constructor theory law isn’t different from the way you would falsify like Newton’s laws or something like that. And likewise, Newton’s laws, as well as the constructor theory laws we proposed intended to be universal so they they they should, you know, apply to everything there is in the universe and that’s why we actually were able to falsify Newton’s laws because at some point we realize that there was in the case and turns out, you know, that they’re actually false. But yeah, I think that’s that’s the, that’s kind of one bit of the answer to your question. The other aspect is that I think because of the way both. Well, David in the first place but also in some sense myself and other people working on this because of the way we are thinking about science.
[00:17:44] Red: It becomes more explicit, perhaps that there is a Popperian influence in, you know, in the way we are, we are posing the problems that we want to solve and so on. And in this sense, maybe other, you know, in other branches of physics, this is not that obvious because people are not perhaps so interested in in these piece of logical aspects of the, you know, the theories that they’re I mean, I don’t think constructed series any more Popperian in its foundations than the rest of science or physics specifically. There is one particular point of contact with purpose epistemology which is the theory of knowledge, and this is something that I think David has been very keen on for for a long time. Knowledge intended as a particular kind of information that can be then defined in a sort of physical manner and puts, you know, this idea of knowledge without annoying subject that somehow is there to pop up directly into fundamental physics so I think that’s one point where say constructed here gets more into the Popperian epistemology camp than other physical theories but this is in this specific regard, not as far as the general foundations which I think are Popperian broadly speaking for physics as a whole.
[00:19:08] Blue: Okay, that makes sense. Now, on the other hand, I noticed that Karl Popper formulates his epistemology using something that at least to me seems very analogous to what you call the prevailing conception. For example, here’s a quote from Popper in the logic of scientific discovery he says for a universal statement without initial conditions no basic statement which would be a testable statement can be formulated. And he’s very specific about the need for and the importance of initial conditions, and he really his epistemology formulates things in something that is basically initial conditions plus universal statements which would be laws, which seems to me to be somewhat analogous to the prevailing conception.
[00:19:51] Red: Yeah, this is a very nice question. And I think the, so I guess that there is this aspect of me perhaps is relevant to to mention that. So in physics in general, not just in constructed theory, when you have a law that doesn’t mention initial conditions and dynamical laws, for example, the conservation of energy. The way you test it is, ultimately, to, you know, to find a prediction about a specific situation which does involve setting up an experiment on the some initial conditions and seeing what happens. So I think the logic of testing a theory does involve as, you know, so Popper said in that quote, the, in one way or another, the fact that you do you do check the kind of predictions of your specific laws in a particular control condition where you can set up an experiment of sorts. So that’s one way in which you can say falsify a particular law. And this is particularly true of principles. Some people think that principles are not testable, precisely because they don’t come as formulate you know that they are not formulated in terms of dynamical laws and initial conditions. But that’s untrue in the sense that you can then given a principle you can check a model that’s compatible with it and then you can
[00:21:22] Green: specialize
[00:21:24] Red: that model in a particular initial condition plus dynamical law type of situation and check the predictions of the model.
[00:21:32] Green: Now,
[00:21:33] Red: the, the important thing is that what we are trying to suggest in constructed theories that the description or the explanation and explanation that only uses statements that you that the result to initial conditions and dynamical laws that this explanation isn’t satisfactory is not sufficient to describe the whole of physical reality. So the, the subtle point is that in order to explain some of these predictions that use dynamical laws and initial conditions, you have to resort to these other things that are not formulated in this way, but can be tested through, you know, predictions about initial conditions and dynamical laws. And these other things are principles about counterfactuals and turns out that actually these are deeper than the dynamical laws themselves. It’s a bit like when you have, you know, you’re thinking of, I don’t know, general activity, it has some dynamical laws and you can set some initial conditions or boundary conditions whatever. But there’s a whole set of principles that come with GR itself, some of which are, you know, describes the, you know, they describe the features of space time and the geometry of space time and so on and so forth. And these principles are actually, in a sense, more robust and fundamental than the dynamical laws themselves. But ultimately the way you test them is to particular, you know, to find a particular prediction that they end up making about a specific dynamical situation. But in a way the dynamical part of this is not the fundamental part the principles are fundamental. Okay, that makes sense.
[00:23:10] Green: One of the reasons why this was inspired the construction theory was inspired was that, you know, any type of concepts that you want to have powerful become powerful physical theory or a concept around which a physical theory could be made such as information. Maybe there might be a push from a physicist to understand it in terms of like the so far considered fundamental physics, like in, you know, fields in terms of some somehow to relate relatable to the physics of the fields or particles and fields or.
[00:23:44] Red: Yes, I think the. So that’s exactly the type of view that we’re trying to counteract. So I think in some way because dynamical laws and fields and so on have been so successful so far in various ways. And because most testing goes through them. There isn’t some kind of assumption that everything that’s fundamental as we formulated in terms of those things. And this is a problem because, as you said, things like information are not the regularities that underline information can be expressed in those terms. And if you try to express in them in those terms, you end up with an approximate theory or with a theory that’s subjective or brings observers into into fundamental physics that doesn’t, you know, of course, satisfy scientific criteria of various kinds and so on. So I think in a sense, what we are pointing out is that in order to stick to this, let’s just use initial conditions plus dynamical laws because they’re very successful. We end up with theories that are non satisfactory or at best approximative for phenomena that are actually very important and they could lead to further important discoveries. And that’s why we’re advocating, let’s try in a different way and take it take that way seriously, which is this one with the counterfactuals.
[00:25:07] Green: Great. And just tying quickly to what Bruce mentioned about popper in a way so I can see that these principles could be tested where the initial conditions aren’t necessarily as you know sometimes people talk about cosmological theories and the initial condition is meant to be like something at a big big bang. But we can just always set up an experiment with some initial conditions, and then we could test out, you know, a certain model, which in a sense would kind of, you know, would be a way of testing, I guess. Yes. Yeah. Okay, great. Exactly.
[00:25:41] Blue: This idea of a perfect prevailing conception I had never heard of that until reading David’s paper in your book. Now I’m not a physicist so that’s not too surprising. I actually found it a little hard to believe that the prevailing conception was a part of physics. In part because of what you said in your book the fact that that Newton’s laws aren’t set up as dynamical laws of motions plus initial conditions so the foundations of physics really was largely rooted in counterfactuals. But talking with Saudi who is a physicist she has assured me that that really is the way physicists tend to think is in terms of this prevailing conception, even though that isn’t part of the foundations of physics. I hope you can see why I’m a little was a little bit confused there. How did the prevailing conception creep into physics if it really wasn’t part of the foundations of physics.
[00:26:34] Red: Yeah, this is an interesting question. Let me speculate a bit about this because I have been myself trying to somehow understand how we we’ve come to this, as you say. Well, I think the one possible answer is that the so as I said the method that uses dynamical laws and initial conditions is just very successful, and it has led to a number of great discoveries. So in physics. So, Newton’s laws aren’t one example but then later quantum theory and general activity and also, you know the atomic theory, the fact that everything. Lots of phenomena can be reduced to microscopic explanations about particles like atoms and subatomic particles and so on, moving about according to some trajectories that are set by the dynamical laws so all of these great steps in understanding reality through physics have been made by largely by appealing to this, you know, this method of explanation through initial conditions and dynamical laws. And I think that has slowly made most physicists lean towards the implicit assumption that any new fundamental law should come in the form of initial conditions plus dynamical laws. So that should be like the, that’s the ultimate type of explanation that you want for the universe and I guess this is not, I think this has been somehow gone unquestioned for for for decades, and it’s been supported corroborated this idea has been corroborated by the fact that it is really a very, very powerful way of doing things it’s it’s stunning it’s just amazing you know the amount of progress we’ve made stick into this kind of logic. However, there is also a different way of doing physics which is already implicit in thermodynamics.
[00:28:48] Red: So there are, you know, these high level principles that some that somehow implicitly use counterfactuals. It has gone largely unnoticed that most of the times when there was a moment of, oh, we need to conjecture a new dynamical law. People were actually using the power of principles such as say the second law of thermodynamics or the conservation of energy and so on to guide them to make guesses for the future laws. So somehow this has gone unnoticed by it’s there. And that’s why I think, in a way what we’re doing with constructor theory isn’t that different from this other tradition that exists in physics it’s just we are extending it to a much broader set of things. And we are hoping that therefore this prevailing conception that I prefer to call the traditional conception because I’m not and I’m hoping at some point it won’t be prevailing anymore will be balanced by the new approach that also uses other tools. And my view is that we won’t make any progress about things like, you know, understanding living systems and understanding the way the mind works and so on from a physics point of view, unless we switch to this to this or a different mode but at least a different model explanation from the dynamical laws initial condition type of logic.
[00:30:13] Blue: So, might, might one say that physics has gotten stuck into an inductive rut where they’re expecting to resemble the past.
[00:30:22] Green: That’s what I was going to say to a field like with quantum theory the success of quantum theory for the longest time under a sort of like an instrumentalist type of way might have actually further, you know, where I think physics started maybe not taking philosophy, giving philosophy it’s rightful place, because even in string theory you seem like the push has been so much from like mathematics being the, the horse that’s, you know, pulling the carriage and seem like they just kind of got carried away without, you know, much philosophy being considered seems like Einstein Einstein actually took the approach where he was very much into philosophy and then he gave principles for his theory. But he actually, interestingly, Barber has pointed out, Julian Barber that he kind of settled more for an operational approach in the end and never really fully addressed some of the question that he actually took over and sorry, I thought I would just mention that maybe to
[00:31:17] Red: it’s a great point I think it’s true that so I guess physics has a huge bias towards empiricism and instrumentalism in various ways. And I think, you know, once this was a good thing because, you know, it was supposed to sort of counteract attitudes, such as maybe dogmatic religious stakes on, you know, on explaining things in the universe. So this was, you know, a good thing at some point, but somehow this has gone out of hand. And to the point that I think it really trumps progress in many directions, in the fundamental sense. So of course you can, there are, you know, countless fields of physics where where people are making great progress and they never have to question maybe their empiricism stake on reality because they’re not wondering about some of these issues that are more, let’s say, the foundations. But when you’re really thinking about the foundations of theories, it’s very important to understand that, as you were mentioning that there is much more to an explanatory theory of reality than just what it’s empirically accessible content. And I think this is a thing that people massively struggle with. And this is also why there are so many misconceptions around there about quantum theory itself, because that’s the only theory where this dichotomy this between empirical accessible content and the explanatory content of theory is most acute. And somehow, you know, people who are really sticking to empiricism and end up forgetting about non empirical accessible content of quantum theory, which is the most important thing in it.
[00:32:58] Red: And they try to somehow fit the quantum theory as it is in some mold that doesn’t belong to it and that’s how we end up thinking about, you know, all sorts of wrong views about, you know, measurements and stuff like that. So yeah, I think it’s, this is empiricism and empiricism and instrumentalism have somehow a huge responsibility in perhaps this fact that physics has got stuck.
[00:33:23] Green: And I don’t know if you felt this way but now that I’ve kind of become after I left grad school in my PhD afterwards I really dive quite a bit into philosophy. And I’ve literally I mean you’re not going to believe this right now I’m thinking about going over all the main branches of physics, because I know that I’m not going to look at the things the same way why aren’t we taught physics with that you know it’s kind of. I mean, don’t, I don’t know if you had that experience or maybe it was just where I took physics that the way physics is taught is very much like the, you know, like, yes, there’s hardly ever talk about like the philosophical implications or it’s, it’s very much as if you would teach an engineer or something, you know, which would be fine but not for. Yes, I think the often I had a larger the same experience and you know, other than maybe for a few fortunate cases of lectures who were not like that but I think most. I mean, the tone of the textbooks and the, you know, the tone of most lectures are is actually based on, as you say, emphasizing what only the predictive content of the theory rather than say, you know, the principal. Yeah, exactly the principles about physical reality and so on. And I think that’s also why I guess physics isn’t that popular, even like in say secondary school settings and so on, because at least the way I was presented.
[00:34:57] Green: Physics was more like, you know, like a set of, it’s like a cooking a cooking book or something a set of recipes to to solve problems that appear to be completely parochial like you know you’ve got to predict what happens to an apple when it falls from a tree. And that doesn’t sound like mind boggling and interesting. Whereas, let’s say the time philosophy was much more interesting to me because it sounded like you know they were asking the right questions about the universe and stuff like that. And then later on I realized actually physics has the chance of answering some of these questions much, you know, in a deeper way than say, you know, philosophy or, or things like religion and so on, of course.
[00:35:39] Red: And it was quite late in my in my study, you know, physics that I realized that he was much more fundamental than the way I was presented it.
[00:35:47] Green: Oh, I had exactly the same experience. And you know, I used to I feel kind of like the odd one out because of the sort of problems that I used to get interested in. And, you know, it felt like I was just some sort of a dreamer or something, whereas I really wanted to know what, you know, like when I took my, you know, the quantum theory course I really wanted to know what what the implications were for the nature of reality and stuff. But our, I remember a professor saying, No, it’s all about how we set up the system and think about these things as a filter. And then when you get out it’s all about predictions and you know I’m like okay, it was kind of a bit of a turn off.
[00:36:24] Red: Yes, and exactly it’s not as you say I mean the the most important part of the of the theories is really needs explanatory, you know, set set of tools and most of them are not about predictions they are really about when you talk about the quantum state. There are also some things that some of them are counter factions, some others are even informally expressed, but they’re all important for the explanation to make sense.
[00:36:49] Green: So this kind of brings me to another interesting question that I wanted to ask you. I wonder whether you’ve thought about because I know in your book you mentioned about the problem of time and I know that you’ve talked to or are familiar with Julian Barber’s work too. I was wondering what are your thoughts on the nature of time do you think that time might turn out to play a fundamental role in physics, because it appears that so far when you look into the theories and I know that quite a few more physicists are becoming convinced that time is pretty much going to turn out to be an emergent concept and Barber, Julian Barber has done work, you know, quite a bit on general relativity and stuff where he’s shown how time turns out to be emergent. But I’m just curious, what are your thoughts since you’ve been thinking about these things in a deep way.
[00:37:37] Red: So in constructor theory, time isn’t primitive, so it’s not one of those fundamental concepts, because when you state for example that a task or a transformation is possible or impossible, that doesn’t refer to, because it doesn’t refer to dynamical law directly, it doesn’t refer to time in the traditional way that say standard dynamical laws do, because standard dynamical laws have time built in as a parameter that that exists and sort of labels different instance of the of the dynamical evolution. And then there’s, you know, this improvement that we got with general activity where space and time ended up being handled in, you know, on the equal footing and there was like a very important step forward and so on. Now, the fact that time isn’t explicitly mentioned when we say a task is possible and so on, doesn’t mean that that isn’t important to incorporate in the constructor theoretic picture of physical reality. And so this is something that we haven’t worked out yet because at the moment the kind of statements we’ve been proving and so on are at the same level as what you do in say the quantum theory of computation, for example, where you’re thinking of composing possible at some point. And the fact that the task is possible exactly refers to all of these things is just that because the tasks are primitives and possible and impossible statements are the primitive statements. We never have to model what the fact that the task is possible means within say a dynamical framework. Would you say that it really wouldn’t matter like let’s say that if time turns out to be some in some sense more fundamental like really fundamental and global rather than emergent as in clocks being emergent.
[00:39:51] Green: You think that, I mean, you don’t think that I think based on what you said earlier when we talked about determinism it doesn’t seem like it’s going to really make much of a difference to construct your theory.
[00:40:01] Red: So the, it won’t make a difference in the in the same way that it does to the dynamical laws right so when, when people say, time isn’t fundamental, and they offer explanations that’s, you know, for how to incorporate time in in in a non fundamental way within the dynamical law, you have to work quite a lot because obviously dynamical law has time built in and then you have to make an awful lot of work in order to go from timeless statements into a dynamical law type statements and so and I think this is what, for example, Julian Barber has been doing for say classical mechanics, and there are similar proposals for, you know, quantum theory, etc. And so it won’t be as hard, you know, it won’t be making much of a difference to construct a theory, compared to what happens in the dynamical law type of approach when you’re trying to say that time isn’t fundamental but it will be important for construct a theory to have a set of principles that underlie the notion of clocks. So clocks are physical systems with certain counterfactual properties. And what David and I would like to to have, and this is something we’re working on at the moment, is a theory that likewise that does the same for clocks as we did for information so we want a theory that tells us what are the principles that have to be satisfied by the by nature for clocks to be possible.
[00:41:39] Red: And it’s an interesting question that you are now posing and something that we haven’t decided yet in a sense, whether this will say that the time is fundamental or not, according to the these criteria that are set by these other proposals that you mentioned so in a way, it will be interesting to see whether these principles rule out or in some of the existing proposals to explain time within standard traditional physics approaches and the answer is very much open so we don’t know at the moment.
[00:42:10] Green: Interesting. Actually, that’s one of the things that I was really kind of interested in looking at Julian Barber’s work and then I looked at David Deutch’s work and then when construction theory came out I was so excited because I sort of I knew exactly what was the inspiration, but but I still kind of lacked like what to do with it but Julian Barber kind of talks about these time capsules or, you know, and I kind of wondered what would be the relation with like some sort of a theory of information but.
[00:42:39] Red: Yeah, there is. Yeah, we expected there is a relation and I think these principles for clocks will be more will somehow necessary principles for even the principles for information to be satisfied. And so this will, you know, this will be contained in this theory that we are trying to construct at the moment for clocks, but I think it’s interesting to see whether these principles will have some consequences in say ruling out some of the existing proposals for for incorporating time within fundamental physics in a way that some, you know, goes beyond the traditional approach.
[00:43:20] Green: So would you say that let’s say and now I’m going to, because based on some of the thoughts that I’ve had, would non locality let’s say that non locality turns out to be some sort of like more fundamental to locality where locality and space are emergent. I mean, I’m thinking that construction theory is going to turn out then to be maybe like, you know, like an approximate theory but what are your thoughts I mean this is kind of what I have been thinking but. So the way so so far, the construct the theory with formulated is based on a very, so very kind of strong principle of locality so in a way, any theory that has no locality built in will be ruled out or at least shouldn’t be a fundamental description of reality could be an emergent one or something of that sort.
[00:44:10] Red: Now I so I this is really a camp where it’s really a kind of intuition so that there are no other reasons than the fact that we have a number of good explanations that are based on locality. So the fact that we have a number of good explanations for physical reality that are local is mainly the reason why we expect, you know, locality to be a kind of good principle to set out and look for better explanations. Of course, you know, it could be that we’re wrong and it would be interesting to find out. And I think, as I said this doesn’t necessarily mean the construct the theory is in itself wrongs, it just would mean that one of the principles isn’t correct. However, I have a very strong feeling that, given the quantum theory and general activity and, you know, the special activities as well are all local. It sounds natural and, you know, nicely rooted in whatever we understand about the universe to expect that next year will also be local. And, however, I mean, I think it’s nice that there are some groups are looking in different directions and I think non locality is the thing that has been sometimes misunderstood because there is this idea that entanglement in quantum theory leads to non locality, and that is wrong. I think it’s a misconception that has been created by a jargon that people created at some point when belt theorem was proposed. Yeah, but I think so, other than the specific use of non locality, which is not quite right. It’s certainly interesting to investigate what happens if you drop locality in a theory and see what other things go away with it.
[00:46:09] Green: And it’s not even like we’re dropping. I mean, I guess what I’m wondering, because I’ve been thinking about Lee Smollin’s work, the recent work where he takes time as global. And then locality is supposed to be like an emergent and so are clocks in that theory would be emergent in a theory like that. But I think that would be an interesting, wouldn’t you agree, kind of like just sort of a thing to try out to see, you know. Yes,
[00:46:31] Red: I think it’s, so I, as I said, I have a strong intuition that that isn’t the way to go, but I think it’s interesting that some people are trying to see what that implies. And it could be that this leads to something interesting too. Note that the theory of information, I mean, all of the good features of information and the fact that we even can set up tests, and the theories are testable does require locality to be satisfied, at least on some kind of scale. So if you, as you say, you know, you might want to have an explanation which is underlying everything, which is non local but then you would want that to be compatible with the fact that locality is satisfied. At a certain level of, you know,
[00:47:18] Blue: Was it quantum mechanics that introduced got people starting to take non locality seriously. By the way, I agree that quantum mechanics does not actually imply non locality. I think it’s very much a local theory. We just did a podcast on that with Sam Kipers. But, but is that where that came from? Like, it seems strange in a way that physics would even toy with non locality as a layman on the outside. It sounds so supernatural.
[00:47:45] Red: Yeah, I think that the intuition of physicists has always been at least the majority of physicists that, you know, put forward various theories was that so they were looking for theories that were local. Newton was greatly bothered by the fact that his mechanics had some local some action at distance built in. There was something that he really didn’t like. And, you know, the theory of fields which was proposed with, you know, first first Maxwell’s equations with light and so on and then later on quantum field theory have somehow managed to Provide a relatively good explanation for a local theory that explains how disturbances are propagated in this local way that allows us to consider the effects on a physical system that is decoupled from the rest of the universe. But I think you’re right that somehow, as probably Sam Kipers mentioned, the well quantum theory was initially misunderstood. And there were lots of comments even from the founding fathers to the fact that Phenomenal like entanglement and superposition could lead to a violation of some of these principles of locality formulated in various ways. This isn’t true. Quantum field theory is basically the, you know, based on the fact that there’s no action at a distance. But somehow this isn’t quite percolated from, you know, the practitioners of that field into the general areas of physics where people maybe are not so familiar with quantum field theory and they’re still doing some quantum theory which isn’t quite Relativistic and so on. And from there to the public. And so I think the idea that quantum theory is non local is is quite widespread. And despite being wrong, it’s still radical, you know, kind of rooted into into the
[00:50:09] Red: Way in which people perceive quantum theory and one of the reasons why it’s quantum theory unfortunately greatly misunderstood.
[00:50:15] Green: And actually, you know, when we do quantum field theory, the locality is actually the starting assumption right it’s not like something that is pretty much we start by assuming that. Okay. Yeah, because it’s not the
[00:50:28] Red: equations are local in that way yeah that’s right. Yes, is some of the resistance to giving up on non locality, because that would kind of force us into a many worlds interpretation and many people are bothered by that interpretation.
[00:50:41] Blue: Oh,
[00:50:42] Red: yeah, very much so. I think the. So I think that there has been this phenomenon which I quite I can’t quite explain where, you know, quantum theory and generally, generally to get, you know, they’re proposed around about the same time in sense in and kind of run same period and they’re both mind boggling theories, and both of them are really interesting and, you know, deep and have got lots of counterintuitive implications, and the quantum multiverse is one of them for quantum theory. But while gr, general activity is, you know, largely considered as very hard to understand but still fine so no one very few people I mean that there is a discussion about what it means and so on but somehow no one has created a case about it. The quantum theory, on the other hand, is actually we are stuck on discussing some things such as is it non local, do we have a problem with measurement, how do we fit classical reality within quantum universe blah blah and all of these questions are actually solved answered very nicely within this many walls or Everettian take or relative states take on quantum theory, which has been perfected since it was proposed by Everett by many people. And, but somehow the fact that, as you say you have to take this step and consider things like different branches of the wave function as coexisting. The fact that the ultimate descriptors of physical reality are not real numbers but they are matrices operators q numbers, which is basically the central tenant for locality in quantum field theory. These things haven’t been swallowed.
[00:52:46] Red: They haven’t been swallowed as much as, you know, the fact that say space time is represented by four dimensional manifold and its geometry is very counterintuitive doesn’t correspond to what we expect. You know, in, in what we see, what we experience, obviously, you know, I perceive my reality around me as just a 3D thing and time is flowing and and it doesn’t seem to match the idea that Einstein suggests within GR, but somehow I’m not using this as an argument against thinking that space time is fundamental. Whereas in quantum theory, even practitioners sometimes get fooled and they say, oh, but I experienced a classical reality. How come, how can this be compatible with what quantum theory says about the quantum multiverse. And I still don’t know why we haven’t moved past this stage given the perfectly fine explanation for how the quantum multiverse works.
[00:53:45] Green: Just to be fair, and this is something I haven’t had the chance to dive into, but I’ve just merely saying it as I’ve heard from Lee Smolin, that when you look at the quantum gravity research so far. I remember him saying that the research in quantum gravity has kind of indicated, there are some conflicts there that seem to indicate that non locality may be might need to be taken seriously at the fundamental level but since I haven’t really explored it I can’t really say much other than just quoting him. I don’t know if you know anything about that or I’m not that well,
[00:54:23] Red: I think that the. So the best approximation we have to quantum theories of gravity are local in the sense that quantum field theory is. Now it could be that I mean I can understand correctly I think Lee Smolin has a view that doesn’t quite that clashes with this idea of the quantum multiverse and I think he’s not happy with it if I understand correctly what he’s thinking. So in some sense maybe that’s why he then goes on to saying well, given that I am not happy with, you know, taking on board that the scriptures of fundamental, sorry, the fundamental scriptures of physical reality are q numbers and not real numbers. Because then I have to pay a price for that and one of the prices you have to pay is the fact that you have to somehow think that that dynamical laws are not local. They are less equivalent to quantum theory, but it’s dynamical laws are non local, and they use additional descriptors that are real valued, which obey these non local equations so if you’re interested in I think possibly Lee Smolin is interested in that and he might. No,
[00:55:59] Green: he actually kind of he talks about in his book and then then he kind of pretty quickly ditches that idea to showing that you know. Yeah, because
[00:56:06] Red: that’s that’s the theory is actually problematic in various ways. So he recognizes
[00:56:11] Green: that I think the motivation is not to get too sidetracked by things seems like his motivation is somewhere coming from certain suspicions from research and quantum gravity. But that may well be there are lots of
[00:56:22] Red: wild different models have been proposed. The problem with these models is that we are not sure how to link them with somehow predictions that can be then tested so in a sense though they might be appealing in some sense it would be nice to have a way of first explanatory reconnecting them with what we know at the scale that we can test.
[00:56:48] Green: Oh he has actually come up with some really interesting tests but not to get away from it again but. Yeah, I don’t think it’s true. I think
[00:56:57] Red: it’s it’s. Yeah, I, I’m kind of very skeptical about that.
[00:57:03] Blue: Well, his, his test the one that you explained to me Saudi it is an existential statement so it actually violates poppers epistemology because it’s not a universal statement. So it’s not actually an empirical test yet in its current formulation.
[00:57:16] Green: Yeah, I guess we can just discuss that some other time. I think it’s interesting.
[00:57:22] Red: This is this brings in another element to the discussion in the sense that quantum gravities. So there are what happened in that domain is that since we realize that quantum theory and general activity are fundamentally different as far as the information theoretic structure is concerned in the sense that quantum theory supports universal quantum computing models and gr is a classical theory so it doesn’t support quantum effects or quantum computation if you like. Well, what happened is that lots of people try to then, you know, come up with very smart proposals to put them together. And we’ve got some kind of working model which is like a quantum field theory model, which we know is incorrect because it doesn’t quite capture the full of the full gr, but at least can provide some predictions in some domains but we know it’s not going to be the right theory because it kind of slot us the whole of gr and makes it not true. And at the same time, we have other models that are mathematically satisfactory but somehow they don’t quite, you know, it’s very hard to actually make them predictive about, you know, some real testable situations. So wouldn’t
[00:58:35] Green: it be fair to say that then that that some other options like right now as as of now there is an open, it’s an open question and we don’t know what might work out at the end. Yes.
[00:58:46] Red: Yes,
[00:58:46] Green: locality has beautifully worked so far but
[00:58:49] Red: yeah, what I want to say is that somehow it’s nice to have additional principles that can help you and guide you to make guesses in this context because most of these proposals are now guided by how do we tweak the mathematics of this or that theory, or one of the other theory in order to merge them together, whereas somehow in addition to this mathematical intuition one should have a very powerful physical intuition the same way they’ll say that Einstein was guided to conjecture his own theories. And somehow we are hoping that some of these theories with with constructed theory can be used to that to that to that end.
[00:59:30] Blue: All right, just as a side note, Kiera mentioned q numbers versus real numbers on the three of anything podcast YouTube channel, Sam Kipers has a lecture that he gives on what the difference between those two is and I won’t go into it but for anyone who’s curious about that he explains the difference between those two. Right,
[00:59:51] Green: thank you. And then. So, one of the things in constructor theory. It seems like you know there’s a mention of universal constructors, but I’ve been kind of wondering, what’s the relationship between, say universal explainers and universal constructor and how do you think the the constructor theory will accommodate universal explainers, what would it take maybe or, or do you think right now, the theory has what it takes to accommodate. Or shed light on actually before I go on the guy, there’s another thing that we wanted to ask you which might be tied to it. So I’ll just kind of read that out as well this was something to do with free will that you had mentioned in the book that unpredictability of action or free will, you said is therefore another counterfactual that dynamical law approach does not seem to be able to accommodate, which I kind of understand now that we’ve kind of talked a little bit about what you mean but maybe if you could say something about universal explainers.
[01:00:52] Red: Yes, so the first thing to say is that the, so this is in, you know, the context is this theory of knowledge that David voyage came up with to say, connect, I would say, perhaps papyrin epistemology with physics. And the, so the seeds of this are back in his his fabric of reality book and then they were expanded on in the beginning of infinity. And also, in the seminal paper on constructed theory where he kind of mentions this idea of knowledge as being a kind of information that has this counterfactual property of being resilient or robust and so in other words it’s got the ability to stay instantiated in or embodied in physical systems. And when I say information again, someone might have a kind of fluffy concept in mind, informally expressed, but I think it’s nice to point out that in constructed theory you can express what information is in terms of these counterfactual properties of physical systems must have so so that’s we, we somehow brought that concept in physics, and therefore saying that knowledge is a special kind of information is another way of saying that knowledge is also a physical thing, just like energies and so on. Now the question is, what are the laws that knowledge obeys. And here’s where you said you were mentioning this, you know, idea of the universal explainers, universal explainers are entities that can formulate universal explanations and therefore can conjecture new knowledge.
[01:02:45] Red: And the question of how does new knowledge come into the world is out of no knowledge is actually a major question that was somewhat addressed by Darwin’s theory of evolution because the natural selection is one way in which knowledge, for example, the knowledge in genes comes about and gets, you know, tentatively constructed through evolution from very simple elementary beginnings. But of course there’s the other process of being knowledge about which is the process of thinking that happens in our brains and possibly happens in other entities in the universe, brains or similar things pertaining to aliens, you know, other civilizations that might exist in the universe. And we don’t know how that process really works, we know it at the descriptive level by, you know, in the epistemological sense so we have this idea of conjectures and refutations and so on. Why is it resilient in some context and it isn’t in others? What creates and destroys knowledge and so on? We don’t have laws about that. So the question of free will is very strongly linked with the question of understanding how new knowledge is created because whenever someone makes a choice, there is some knowledge being created about, you know, the explanatory reasons why that choice is made, that’s another. And so the whole of this problem of free will and explaining, say, knowledge creation more broadly within physics cannot be phrased even within the traditional conception because the traditional conception is just about the universe going along a specific trajectory which has a specific initial condition. And once you are in that trajectory, there’s no knowledge or that there are no choices being really made because it’s just one thing after another.
[01:04:52] Red: So in a sense, the fact that I appear to have the choice now to, after we’ve spoken, you know, go and read a book or go and have a walk, that isn’t quite true, it’s just a Now, in this context, I think one way of getting out of this problem, which is the thing you mentioned, is that you could still say that there is a certain unpredictability as far as my decision is concerned because the only way in which say you could come up with a prediction about what I will do and therefore show that I’m actually predetermined is to have a full simulation of me as a brain, let’s say, a copy a clone of myself that will then come up with the, you know, decision and then this happens before I make this decision and then you will know ahead of me what choice I will execute. But suppose that there were a principle of physics that said that it’s actually impossible. So another counterfactual for you to come up with this simulation with certain limited resources that we have available. Well, that would be one way in which some of these statements that have been suggested in order to explain how the emergence of free will is actually compatible with determinism in physics, could be quantitatively explained within physics. So that’s one way in which I was conjecturing the in the book, along the line source of what David conjecture then and others that construct a theory could solve this problem at least provide the tools to address the problem once and for all. So this next. Yeah, sorry.
[01:06:44] Blue: Well, I go ahead. I want to finish what you were saying and then I have a question about it.
[01:06:49] Red: No, I just I just wanted to and finish with this question about universal explainers that the Saudi mentioned the disconnects to the universal explainer’s problem because So construct the series is supposed to be a generalization of the quantum theory of computation to cover not just universal quantum computers or Turing machines, but also those objects that for no man called constructors which are programmable machines that can be programmed to perform other tasks and computations, like building a house or constructing a computer, a fresh or doing some other, you know, cooking something preparing coffee or something like that. And, and then there is a universal construct which is like the most general social machines that has the ability to perform all computation all transformations that are physically permitted. But constructors are not don’t have this free will thing so they can be programmed, and they will execute whatever problem you put in them, but the thinking brain has the ability of somehow, you know, be programmed to do something and do something else. And that’s, I think the saddest question was going, can these entities also be explained within construct the theory and the answer is, we don’t know, but we’re hoping that they will be explained. And it’s important for this. It’s the key to crack this problem. So
[01:08:20] Green: when you said that you think it will be explained does that have something to do with the type of law or the way this comes about. What would it be like.
[01:08:29] Blue: I guess Bruce you had a question because I kind of let me let me ask my question. So, I was actually surprised by what you said in your book about that. You mentioned something called the deterministic nightmare. And the reason why I was surprised is because I had understood that problem is not existing at the level of physics but being an emergent property of computational theory. So I had a thought experiment that I actually invented for a totally different purpose but the thought experiment was, suppose you have an eight you know a computer that’s running one or more agis, and they have some sort of environment that they’re living in that’s sealed off from our world, virtual world, it may not be very much like ours. You can imagine the computer being either a classical computer or a quantum computer. Wouldn’t they then be living I mean like the, they aren’t interacting with our physics they’re they’re completely at the emergent level but to the best of our knowledge, according to computational universality. We should be able to make a virtual world with one or more agis in it, that our knowledge creating entities and that are people. Wouldn’t they then be in this deterministic deterministic nightmare. Even though that what you call the deterministic nightmare, even though they’re not part of our physics. I think they would be. But the question is, is there still a sense in which even if you assume this deterministic nightmare scenario. Is there still a sense in which you can say that all of these agis, each of them has some inherent unpredictability as far as their own thoughts and choices. I see.
[01:10:11] Blue: So let me, let me just take that one step further than I, I would assume, I mean like Stephen Wolfram talks about this. There is no way to predict the vast majority of deterministic computations so presumably they aren’t predictable the first time. But what if you’re running two of them and ones on a slower computer, the second one would be predictable under this thought thought experiment wouldn’t it.
[01:10:32] Red: Yes, it would be but the question is predictable means something. So here is the kind of problem that currently the sense in which predictable or computable is used. It’s somewhat always referred to this realm of the Turing machine so the Turing machine is a highly idealized thing that is already very complex and exists in, you know, it’s supposed to exist. Somehow by fear and then you can refer lots of statements about computability or possibility of certain things to that. So like if you had the Turing machine and blah, blah, you don’t worry about the resources that you need to run it. Would you be able to say, I don’t know, predict that certain program will hold or not or something that sort. Now, the, these problems are meaningful within the current complexity theory, because that’s all rooted in the Turing machine model. But to give a physical answer physics answer to the question, can I can, you know, is it possible to predict the thoughts of an over of a kind of brain that’s thinking. So a physics question to that answer has to take into account other things, particularly it has to take into account resources with which this task has to be accomplished. And it’s not valid to give an answer to that question, assuming that you’ve got a Turing machine available. And so that’s where constructed theories are relevant because it goes outside of this complexity theory type of scenario where you’re only referring everything to an existing Turing machine. And he’s saying, no, Turing machines are actually emergent objects that presuppose over. I mean, they’re already assuming lots of things to be available. Let’s not assume that. And let’s ask the question from a fundamental physics point of view.
[01:12:36] Red: And there we don’t have the answer in the sense that, in principle, yes, it’s possible. But that depends on the constraints that I’m putting on you. So for example, if I’m asking you to do this in a limited amount of time with limited resources, you may not be able to do it. And so all of these statements currently are very informal and they are very qualitative and a bit imprecise. But the hope is that we construct a theory, you can actually have a complexity theory, which is more rooted into physics than the current complexity theory. And this will also answer this question about what does it mean to emulate the thinking of a human being or a brain.
[01:13:15] Blue: If that were true, wouldn’t that violate universal computationality?
[01:13:20] Green: Or the interoperability? I mean, I was actually kind of thinking along the same lines, too, that is the worry that what if, just to give it hypothetical, what if there’s some new sort of a law at play? There’s some element to it where interoperability is not possible, like matter and whatever this new law is operating on kind of communicate, but there are only two certain channels, but there may be other things. In other words, there may not be some sort of a unified theory that could connect the two. Okay,
[01:13:54] Red: well, that’s one reason why, okay, that’s not the physics we think we have, but it could be that we are in a physics of that kind, in which case lots of things to do with universal computational may not be true or might have to be revised. So that’s one scenario that’s possible, it’s not, I don’t think it’s plausible, it could be the case.
[01:14:19] Green: Like a big form of dualism right here that we’re. Yes, although then, you
[01:14:24] Red: know, because we are thinking that there is always some way of explaining, let’s say if there is a dichotomy of that sort, there should be a law that explains why that is, you know, that there are two kinds of information that they’re not interchangeable. A bit like, you know, when in, in GR, we say that mass and energy are equivalent and mass or energy couples in with other things in the same way they’re not different kinds of masses or energies. Likewise, your information is similar in that sense. And if it were not, if you had different kinds of information then you would really have to have a good explanation for why that is. So it wouldn’t be really like a dualism, it would be more like, oh, I have, you know, really new groundbreaking explanation and this would probably lead to also some interesting phenomena that I can’t even conceive at the moment.
[01:15:20] Green: I guess in a way we wouldn’t even be able to access that so it’s almost would be kind of like invoking supernatural in a way, right? Yes. And in
[01:15:28] Red: response to Bruce’s question, I think the, I mean, the university of computation is based on the model. So it’s kind of assuming a certain model of the Turing machine and the Turing machine is running with side effects. And no one cares when you talk about computation, no one actually ever somehow models that those and that’s part of the reasons why complexity theories and currently satisfactory, because it’s satisfactory for some purposes but it doesn’t quite do the job of addressing old tasks. And that’s also why the theory of computation despite the university of computation is not the whole of physics. That’s one other, one of the key insights I guess that David has in his constructed theory paper is that that was one of the things that hooked me at the start of my interest in this topic is that it’s not enough to just study computers in order to understand the universe because there are things that in programs are not distinguished. For example, models of the universe with different values of the fine structure constant. They all those programs are all the same, as far as your computation is concerned but as far as physics they’re very different and constructed here is needed to extend the quantum theory computation to the whole of physics precisely because of this reason.
[01:16:58] Blue: Okay. Um, actually, can I ask about the, the dust question. Because I was actually curious about that because it relates to the interoperability in the book. You mentioned this thing called that is theoretically you made it up it’s not necessarily a real thing but it’s this thing called dust that
[01:17:17] Red: yeah,
[01:17:18] Blue: only interacts with our universe, you know through gravitation, or something along those lines, and how that would then violate the theory of interoperability and there would be no way to build a universal computer in such a universe. Did I understand that correctly first of all, I want to make sure I understood that correctly but is that what you were trying to say in the and then, and then that was kind of inspired by dark matter right because that’s like one of the theories of dark matter is that it’s just like what you call dust.
[01:17:50] Red: Yeah. Yeah, I think I. So I wanted to be a little bit more general I didn’t want to refer to specific models because all of them are have their own details and I didn’t want to enter that specific discussion so somehow wanted to be very broad. But I think the. Yes, I guess this is one way of showing why understanding the physics of information has important consequences also to rule out or ruling or understanding implications of some of these models that we have for the universe. For instance, the fact that we, you know, the fact that we assume that computers are interchangeable in some way and bits are interchangeable and that there are no two different kinds of bits that can be copied on to one another. Also means that we are not allowed to assume that there are sectors of the universe which are not, which are kind of severed from from ours in a fundamental way. And so, you know, any kind of interactions that we are, if we’re postulating these two sectors of the universe, any kind of weak interaction that might happen between these two should be strong enough to be amplifiable to then perform a copy like cooperation so that information in our sector information in the other sector are interchangeable and if they’re not, then we have to be prepared to consider the fact that, you know, universal computers may not be possible in the way that we think they are now.
[01:19:29] Red: So that’s one way of illustrating why the physics of information is not just some kind of quirky, non fundamental emergent theory that maybe might be of interest for engineering and technology, but it’s actually quite deep and it puts lots of restrictions the same way that, for example, nervous theorem puts restrictions on the kind of Lagrangian mechanics that we expect described some of our most fundamental models at present.
[01:20:00] Blue: Um, this is probably an out there question, but that made sense what you just said. Why is that not also true for many worlds quantum physics where you have worlds that deco hair for me from each other so that they can’t have interoperability between them anymore. Does that also imply that there’s no such thing as a universal computer.
[01:20:20] Red: Oh, no, that is not the case because the point of the. So the different. So the point, so the different branches of the multiverse are not. Universes in the same sense that say they are. I see. So it’s, it’s still possible to reconcile the existence of these universes with the interoperability of information with the fact that in each of these universes information is interoperable.
[01:20:54] Blue: I say that actually makes perfect sense. Okay.
[01:20:58] Green: Would you say that then the conservation of information is important, because, you know, like in the multi worst thing we can define this thing called, you know, the super information. So the whole idea is that they’re all, you know, they operate under the same laws but there’s the super information. So if, if, like, like, if the information was not conserved like first of all I know that the way even if it’s defined, it’s defined, you know, there’s. Does that question make any sense as to what I’m saying that is in conservation of the information and important thing for constructed theory right.
[01:21:32] Red: Yes, yes it. Well, I guess maybe one should be a bit clear about what we mean by conservation of information by I guess. Yeah, there is a sense in which the interoperability of information has some kind of analogy with the idea that the type of information has to be preserved in different interactions and when you put two systems together, each of which can kind of work as information medium, the composite system should still conserve the capability, you know, this is the conservation of counterfactual properties if you like. And so yeah, I think in a way it’s a good analogy to think of the interoperability of information as stating some kind of conservation of information. But
[01:22:22] Green: when we going back a little bit at the beginning of our discussion we kind of discussed that what if there was, and I don’t know if you use the word information there but what if there were what if the universe was creating some new laws through some sort of an evolutionary process. You know, I mean there I kind of struggle that with that, like, you know, obviously, to me it would seem like the universe would be creating new information any thoughts on that or, or let’s say that if, you know, a second law of conservation turns out to have the final say. I know that in, you know, the way the many worlds interpretation deals with is that the information kind of branches out. But let’s say somehow, you know, the universe could create maybe will restrict to you know we’re creating new laws. I guess that do you think the information would be conserved or I don’t have some fuzzy thoughts there but maybe.
[01:23:17] Red: Well, it’s, it’s, that is a nice question. I think the, as I said, perhaps we should be a bit more clear about what we mean by conserving information.
[01:23:31] Green: conservation conservation basically just means that okay, even if there was a new law and we discovered it, it would become part of our picture, but that doesn’t necessarily mean that there was some given information. Yeah, since the big bang that we’re just uncovering right.
[01:23:46] Red: Yes, you could think of some done up so the fact that information is concerned one way of thinking about it is that distinguishable things that are distinguishable. So the degree of distinguishability of things doesn’t get changed with dynamical evolution so you know if I can, you know, if I got two states of over of a system like a flag, one is red and the other one is blue. And then I apply some dynamically allowed transformation, and I change them into some other states, then I expect the final states of these two flags. If we are just applying, you know, fundamental dynamical evolutions to still be distinguishable. And a dynamics whereby blue and red get glued together and they turn both to be you know that kind of the flag gets both flags get colored by the same color are dynamics that are possible with side effects so there has to be some track of the fact that I just erased the difference between these two states. That’s what a dynamical load of conserves information does. And I guess you could imagine a law like, you know quantum theory that has this feature that conserves information in this sense, and then a different law that still does that but it’s just different from quantum theory. So the fact that the universe might be going through these laws as you know into in some of these hypothetical speculative models doesn’t necessarily mean that the information gets deleted or erased in a way that values conservation of information in the sense that I said. So yeah, I think it’s possible that some of these models are compatible with the principles of information that as we know them now. All
[01:25:37] Red: right, just as a side note, we are at an hour and a half.
[01:25:42] Blue: So it might be good to start wrapping this up and yeah, Carol, get back to her life here. And I’ll be erasing this part of the show where I just said that. No problem. Do we do we want to allow any final question or should I go ahead and wrap things up.
[01:26:01] Green: Fine with me I could go on forever but yeah. This is so much fun. All right.
[01:26:08] Red: Yeah it was really nice I enjoyed it too. By the way I mean I’m happy to continue conversation and you know it’s some other point or through emails or whatever way.
[01:26:19] Blue: That would be awesome. I know that I feel the same way as Saaya this is like great having someone to ask a lot of these questions.
[01:26:26] Red: Thanks guys it’s really nice I enjoyed I enjoyed to yeah it was really nice questions to very very nice.
[01:26:32] Blue: All right, thank you so. Um, thank you for coming on the show we we really appreciate it this has been a an exciting episode and I know that I’m just very grateful for you being so willing to share your time and your mind with us like this so thank you.
[01:26:49] Red: Yeah, thank you. Thank you for having me was
[01:26:52] Green: was real fun. Yeah, thank you very much. This was such a treat. Thank you very much. Thank you.
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