Things that make you go mmmmm? Part 3: Multiverses

00:00:00.000 Welcome to Topcast, N2 part 3 of Things That Make You Go, My Exploration Of
00:00:12.720 The Maddox Morality Multiverses as this one will be about Metaphysics, and many other things that
00:00:20.080 are covered in the conversation between Max Tegmark and Sam Harris. That's okay,
00:00:26.400 saying it's a wonderful conversation. Go looking online for the podcast. If you sign up as a
00:00:32.400 member of Sam's Community, then you get access to the entire podcast, which is what I've got
00:00:36.800 access to. Or you can buy the book of conversations, which includes the conversations with David Deutsch.
00:00:42.480 That's part one of the book, and there's an audio version of it, and Max Tegmark as well,
00:00:47.040 which is the very last part of the book. So as I said before, two great thinkers to begin an end,
00:00:52.320 a journey through the Making Sense series. Today, this one is about Multiverses. Now, I've got an
00:00:58.160 entire series online about the Multiverse. The Multiverse, as I understand it, what we know
00:01:04.240 exists is what it's known as, the Everrittian Multiverse, the Quantum Multiverse. The Multiverse
00:01:10.240 that is explained in the fabric of reality and the beginning of infinity, that quantum physicists
00:01:15.760 talk about. So it is said an interpretation of quantum theory. We don't regard it as an interpretation.
00:01:21.760 Any more than one would say dinosaurs are an interpretation of fossils. In a sense they are,
00:01:26.880 but there is no other viable interpretation. Now, of course, many physicists, many quantum physicists
00:01:32.080 will disagree with this kind of thing, and say, oh no, they don't endorse the Multiverse. Now,
00:01:37.680 sometimes this means they're an instrumentalist, in which case they're not endorsing
00:01:42.480 any particular interpretation. They are retreating from interpretations, full stop, and hence
00:01:48.320 explanations full stop. They're only interested in predictions, so they say, so they claim.
00:01:53.440 And I would just say of that, it's completely irrational, because you need to understand what you're
00:01:58.400 doing. Simply being able to predict the outcome of experiments is not understanding and explaining
00:02:05.840 reality. And even if we don't have a perfect explanation of reality, your job as a scientist should
00:02:10.160 be at least in part to try and understand reality, to give us the best explanation. That's one thing.
00:02:15.440 Other physicists who deny the reality of the Multiverse and try and come up with their own version,
00:02:21.200 what they end up doing when you look at the details, something like bones, pilot wave theory.
00:02:25.680 I've read quite a few interpretations over my time. Paul Davies has that wonderful book
00:02:30.720 Ghost in the Atom, where he goes through a large number of interpretations. There's been a few
00:02:36.160 popular science books written recently, I think they get written every other year, about, you know,
00:02:41.360 some physicist pet favorite interpretation one they've made up. Well, these all fall into two
00:02:48.000 categories. They're either going to be of the instrumentalist bent where they're just denying that
00:02:53.200 you can have a proper interpretation and so just calculate. That's one way the popular scientist do it
00:02:58.400 and the physicists. And the other is just to disguise the multiverse in some way, shape or form.
00:03:04.080 It's the multiverse in heavy disguise as David Deutsch liked to say. What happens is they postulate
00:03:10.560 the existence of, think you can't observe. In other words, physical reality, the reality we
00:03:16.720 inhabit and the reality we have access to in a sense directly is being impinged upon by other entities
00:03:24.240 in reality that we can't observe. So these other entities in reality, although these physicists and
00:03:30.800 these popularized of science might say things like, I don't endorse the multiverse. I think that's
00:03:34.880 a proliferation of universes, it violates Occam's razor, it's just crazy metaphysics or whatever,
00:03:41.120 nonetheless, their own interpretation tends to invoke the existence of stuff you don't have
00:03:47.280 experimental access to in quite the same way. You have to infer its existence and all we say about
00:03:52.880 that is, well, yeah, you're inferring the existence of stuff. Okay, that other stuff occupies a
00:03:57.520 different space. It's not here now, but it's having an effect on the stuff you do observe, the stuff
00:04:02.320 you do is see. You're explaining why you get interference effects because something's affecting
00:04:07.760 the path of those photons of those electrons or those particles. Something that you can't see,
00:04:12.480 but you're saying it really exists. That's the multiverse. Now you can call it whatever else you
00:04:17.040 like. You can call those other things by Christian names if you prefer, but the fact is they exist.
00:04:22.800 You're saying that other stuff exists and that's what we say the multiverse is. Now we have a
00:04:26.800 richer explanation. I cohere in an explanation that just says, well, for each particle you do observe,
00:04:32.480 there are counter parts of that particle, fungible instances which can differentiate themselves
00:04:36.720 and thereby cause interference. So whatever the case, this is the ever-ready and multiverse,
00:04:41.360 which as I say, it's unusual in that Max Tegmark does endorse a version of this,
00:04:47.040 a version of this, but it's the one kind of multiverse that is not talked about really,
00:04:53.200 it's not really referred to here in the making sense podcast with Max Tegmark. So a lot of
00:04:58.720 this part of the conversation between Sam and Max, I'm skipping past. In fact, I've missed an entire
00:05:03.760 bit and I'm not going to talk about it at all where they do discuss information and its
00:05:07.760 relationship to mathematics. I'm going to skip over that. And here as well, I think I can skip
00:05:12.800 through a lot of the multiverse stuff because if you go back to part one of my treatment of this
00:05:17.920 conversation, what you will see there is that I basically summarize the four levels of multiverse
00:05:23.920 that Max endorses in somewhere. I don't know, talk about it there. So I won't go through that
00:05:28.400 again now, I'll let Max just speak and then he moves on to the simulation hypothesis and I'll have
00:05:34.400 a few things to say about that. So let's get into the discussion today.
00:05:40.080 So I now want to get into the multiverse, which is probably the strangest concept in science now.
00:05:46.160 It's something that I thought I understood before picking up your book and then I discovered there
00:05:51.600 were there were three more flavors of multiverse than I realized existed. I want to talk about the
00:05:57.280 multiverse, but first let's just start with the universe because this is a term that around which
00:06:01.920 there is some confusion. Let's just get our bearings. What do we mean or what should we mean by
00:06:05.680 the term universe? And I want to start with your your level one multiverse. So if it's possible,
00:06:12.000 give us a brief, brief description of the concept of inflation that gets us there.
00:06:20.560 Sure. So what is our universe, first of all, before we start talking about others,
00:06:25.200 many people sort of tacitly assume that universes are synonym for everything that exists.
00:06:31.440 And if so, by definition, there can't be anything more and talk apparently universes would just
00:06:35.680 be silly, right? But that is the, in fact, not what people generally in cosmology mean when they
00:06:40.720 say universe, and they say our universe, they mean the spherical region of space from which
00:06:47.600 light has had time to reach us so far during the 13.8 billion years since our big bang.
00:06:52.800 So that's in other words, everything we could possibly see even with unlimited funding for telescopes,
00:06:58.960 right? And so if that's our universe, we can reasonably ask, well, is there more space beyond that,
00:07:05.280 you know, from which light has not yet reached us, but might reach us tomorrow or in a billion
00:07:09.920 years? And if there is, if space goes on far beyond this, if it's infinite or just vastly larger
00:07:16.800 than the space we can see, then all these other regions, which are as big as our universe,
00:07:22.000 if they also have galaxies and planets in them and so on, it would be kind of arrogant to not
00:07:26.880 call them universes as well, because the people who live there will call that their universe.
00:07:31.680 Unfair or misleading in a way. You see, Max defined into existence there, something that
00:07:46.000 someone who trained an astronomy and far be it from me to quibble with a world-renowned cosmologist.
00:07:51.920 But what I was taught throughout my degrees in this was that we know as a matter of big bang
00:07:58.560 and inflation cosmology that, of course, there is this thing, the observable universe which
00:08:03.360 max defines quite rightly there as the region of space where light has had time to reach us.
00:08:10.080 But we know as a matter of fact that that's not all of space that continues with that
00:08:15.760 and continuing to expand is space beyond that. Continuous with that is just that the light hasn't
00:08:21.360 had time to reach us from that particular region just yet. So you can go all the way to the
00:08:27.440 deepest recesses of space, so I don't know how far it is, 40 billion light years away, by the
00:08:32.080 way it's further than 13.7 billion light years because of inflation, because of the expansion of
00:08:37.200 the universe. So from here to the furthest away possible is something like 40 billion light,
00:08:41.600 is whatever, this spherical region of space. But we know there's space beyond that.
00:08:45.520 The theory tells us that. And then in fact, because space is expanding at those furthest,
00:08:50.160 farest reaches, faster than the speed of light and space can expand faster than the speed of light.
00:08:55.440 Einstein's theory of relativity says you cannot move through space faster than the speed of light,
00:09:00.800 but space itself can expand faster than the speed of light. So there are galaxies there at the
00:09:04.960 edge of the universe, which are moving beyond being expanded beyond what we can see. So
00:09:10.080 that might be visible today, but cannot possibly be visible tomorrow because they've disappeared
00:09:15.760 beyond the horizon of light where light can reach us. So we know this is going on, this is a matter
00:09:20.720 of science, this is a matter of normal science. So this is why generally when this kind of material is taught
00:09:25.440 to students of astronomy and cosmology, they're taught. So therefore you've got this observable
00:09:30.720 universe, this ring. And then out of that is another concentric ring, concentric sphere would be
00:09:36.240 more precise of a region of space, continue, perfectly continuous with that, which contains
00:09:42.160 the galaxies and planets and all that other stuff, all the stuff that we see, but it just goes on
00:09:46.640 even further beyond what we can see. So that's all the universe, okay? So the physical universe is
00:09:52.560 that thing, and that's usually what astronomers, astrophysic cosmologists refer to as the universe,
00:09:58.240 and they distinguish that from the observable universe. That's why, to be honest, it's
00:10:02.960 just idiosyncratically Max Tegmark, as far as I'm aware, who refers to this as the level one
00:10:08.400 multiverse. So it just seems a bizarre way of confusing people and people already object to the
00:10:14.240 idea of multiverse. But so it's kind of, it's a little off-putting, which is why, you know, people
00:10:20.240 just say, just talk about the universe, just everything that exists. Some stuff that exists,
00:10:25.840 we can't see, and we've talked about that ad nauseam on here. So this is why I say level one
00:10:30.720 multiverse, I don't know if it cancels a multiverse, it's more like just the universe.
00:10:34.720 And the strange thing is Max concedes as much himself soon in this conversation. He just says,
00:10:41.280 well, the level one multiverse, that's just another way of talking about space, space.
00:10:47.600 So the only reason for the term here seems to be to distinguish between the region of space
00:10:53.440 that's observed or observable in principle, and the region of space that is not observable
00:10:58.320 in principle. But if that's the criterion, a spatially connected region that's not observable
00:11:04.800 in principle, scientifically, well, it's the core of a typical star, another universe in some sense.
00:11:11.680 Is the innards of a black hole, another universe in some sense? Well, of course, some cosmologists
00:11:16.000 might actually argue that. Well, the innards of a neutron star then, you know, not observable
00:11:21.120 in principle. We don't have any good explanation about how you would even go about beginning to build
00:11:25.200 an instrument that would be able to get there. Another universe, no, I think this is misleading.
00:11:30.320 This is just an unnecessary use of a term which should be used precisely in science. We want
00:11:36.320 precision with our terms to the extent that we can get precision. Yes, everything is ambiguous
00:11:40.880 and all that sort of stuff granted. We should try and have an economy of terminology,
00:11:46.480 especially precise scientific terminology. I think it just degrades things. We just start
00:11:51.040 throwing the words around everywhere. All right, I've made enough of a point on that. We'll come
00:11:55.920 back to it again shortly. Let's keep going anyway. And inflation is very linked to this,
00:12:03.120 because it's the best theory we have for what created our big bang and made our space the way it
00:12:09.040 is so vast and so expanding. And it actually predicts, generically, that space is not just really big,
00:12:17.200 but vast. And in most cases, it's actually infinite, which would mean if inflation actually
00:12:22.560 happened that what we call our universe is really just a small part of a much bigger space.
00:12:28.080 So in other words, space then is much bigger than the part of space that we call our universe.
00:12:34.720 This is something actually I don't think is particularly weird once when it gets
00:12:37.440 into terminology straight, because it's just history all over again, right? We humans have been
00:12:43.600 the masters of underestimation. We've had this over-inflated ego where we want to put ourselves
00:12:50.000 in the center and assume that everything that we know about is everything that exists.
00:12:54.400 And we've been proven wrong again and again and again, discovering that everything we thought
00:12:58.080 existed is just a small part of a much grander structure, a planet, solar system, a galaxy,
00:13:05.600 a galaxy cluster, our universe, and maybe also hierarchy now of parallel universes.
00:13:12.240 So it makes us of course quite right there about the history and it's a point I've made here
00:13:21.040 on talkcast many times before. The history of science, the history of physics, cosmology in
00:13:26.320 particular, astronomy, is this history of gradually our understanding becoming ever larger of
00:13:33.120 stuff, our understanding. And so we used to think it was just basically planet Earth with
00:13:37.840 celestial spheres and we didn't know what they were. But then we figured out we actually
00:13:41.200 occupied this thing called the solar system, which is bigger than the planet. And we realized,
00:13:44.560 well, the solar system is actually inside this thing called the galaxy. Oh, the galaxy,
00:13:48.480 well, it's just one among many galaxies. Oh, it's got this whole thing called the universe,
00:13:52.480 and well, it shouldn't be much of a surprise that we have this multiverse. Now,
00:13:55.680 the only sense in which I disagree kind of with Max here, I think, is that the proper epistemology
00:14:02.560 allows you to distinguish between what's known in the sense of having a good explanation,
00:14:08.880 a solution that solves a particular problem and no longer has any rivals. And so,
00:14:12.800 therefore, you say it is the explanation of something and competing hypotheses where you don't
00:14:19.120 really know and you don't even have a method of being able to test for these things just yet.
00:14:23.840 And then you can't rule out the alternatives. That's a key thing. You can't rule out the
00:14:28.240 alternatives just yet. So you can't say you know these things. So these are not all on equal footing.
00:14:34.160 These levels of multiverse are not on equal footing for that reason, but the way that Max talks
00:14:39.280 it's as if it's as if they're kind of, you know, they use all existing, you know, you buy one,
00:14:43.920 so why won't you buy the other ones? Well, because some of them are well known good explanations
00:14:49.120 to solve a particular problem, because that level one multiverse, which I just again insist on
00:14:53.840 calling the universe, it solves a particular problem. It enables us to explain observations of the
00:15:00.800 actual universe that we have in cosmology, like the cosmic microwave background, like the ratio
00:15:05.840 of hydrogen to helium that we observe out there in outer space, like the expansion, the red shift
00:15:10.800 of galaxies, the expansion of space. So it solves these things. So the dark night sky is another one.
00:15:14.880 So this is solved by postulating and expanding universe and the universe, therefore, beyond what we
00:15:21.600 can actually observe. So that solves a problem. The ever ready in multiverse solves a problem. It's
00:15:26.320 like, how do we explain the observations of things like interference experiments ever ready in multiverse?
00:15:31.440 We need to invoke the existence of these parallel other universes that contain fungible instances
00:15:37.120 of every single particle. Okay, so that's that. But then when we get into these other ones,
00:15:41.120 these level two multiverses and especially level four multiverse, they are hypotheses that aren't
00:15:48.800 yet that don't get catas good explanations. Why? Well, because in the case of let's take level four,
00:15:53.680 let's take level four. The level four multiverse is, is this idea that all different physical laws
00:16:00.240 exist out there somewhere rather. So all the logically possible universes are out there somewhere
00:16:04.720 other. Now, the overwhelming majority of those are governed by physical laws, which are completely
00:16:09.040 hostile to life. So why would you think this thing up? Well, one reason you would think up this
00:16:13.920 plenitude, these other universes with other physical laws is to solve the problem of why the
00:16:19.680 constants of nature here in our universe appear to be finely tuned. Now, I think the fine
00:16:25.280 tuning problem is a problem. But there is a debate in physics between physicists, some of whom say,
00:16:30.160 well, it's not a problem. But here's the thing, we don't know the answer to this fine tuning problem.
00:16:34.960 We don't know why the constants appear to have been finely tuned to allow for life here in this
00:16:40.160 universe. Change any of the constants, max will come to this and you won't get life. Change them
00:16:45.200 by too much and you won't get life. But here we are. It seems a remarkable coincidence that
00:16:49.360 conditions are just right when the Goldilocks zone, not only for one concept, but for all the
00:16:54.160 constants, that's remarkable. It's a remarkable thing. One such solution is, well, you've got this
00:16:59.520 multiverse. So if all the other universes with different physical laws, most of which don't have
00:17:03.040 life. So why should we be surprised if all the other universes are out there? Of course, we're
00:17:06.560 going to find ourselves in the one that is very bio friendly, it's friendly towards life and
00:17:11.520 intelligence. Okay. Now, truth be told, you don't even need level four for this. You just need
00:17:17.440 max is so-called level two multiverse, which he's coming to shortly. But he switches between these
00:17:22.880 things pretty fast in this conversation. So sometimes it's hard to keep track. Level two is just the
00:17:28.240 class of universes defined by all solutions to string theory or something like that.
00:17:33.920 Whatever, all our physical constants, they still exist in those other universes, but they take on
00:17:39.040 all possible values somewhere or other in that multiverse, but presumably quantum theory and general
00:17:45.280 relativity, they still hold or string theory still holds. So the laws themselves are the same,
00:17:50.560 the form of the laws, but the constants are not. So this is one way of arguing about fine tuning
00:17:57.360 and one way of solving in scare quotes, the problem of fine tuning, we find ourselves in the
00:18:03.440 universe or in one of these small number of universes where the constants are just right and all
00:18:09.280 the others actually exist out there somewhere other. Of course, you could have wildly different
00:18:14.640 constants and wildly different physical laws, making a bio-friendly universe. And then you might
00:18:21.600 get life, but that's level four. Indeed, in level four, you might not even have a constant at all.
00:18:27.760 You know, as what goes on in level four, you just have every logically possible universe,
00:18:33.840 every logically possible thing in some magic really does work. The Star Wars universe is actually
00:18:40.880 out there, literally real in this level four universe. Universe is violating conservation laws
00:18:46.320 and universes we can go through space, fast and light, add in for an item, add in for an item in
00:18:51.680 every single sense there. That's called the plenitude. David Lewis wrote a book, like I said,
00:18:57.040 about this. And this, by the way, makes the plenitude easy to vary. The plenitude, all logically
00:19:03.600 possible universes or what Max calls the ultimate ensemble, anything that in his mind is even
00:19:09.600 conceivable. But I would say, actually, conceivable is too limited a word for this. Maybe what is
00:19:16.160 inconceivable still exists and still counts as possible. Why is our ability to conceive it?
00:19:22.800 A constraint on what logical reality is as a whole. A doubt we can get agreement on what counts as
00:19:29.520 conceivable or logically possible is God, the Christian God logically possible?
00:19:35.520 What about Zeus? What about other creator gods? If they're logically possible,
00:19:40.400 if they obey logic, then they exist out there somewhere other than they're creating universes
00:19:45.200 and presumably our own two in an infinite number of universes. Or if these gods are not logical,
00:19:51.520 never mind physical, then what is logically possible? And are other logics permitted in these
00:19:57.200 other logically possible universes? After all, what we consider logical is what is
00:20:02.480 noble to us, as logical in this universe, obeying these laws of physics, perhaps in other
00:20:08.080 universes with other laws of physics, they can compute stuff which includes coming to know things
00:20:11.760 that includes an understanding of a logic deeper than ours or different to ours. This is
00:20:17.200 quickly becoming mind-bending self-referential stuff, illogical perhaps. So whatever the case,
00:20:24.080 maybe then Yahweh doesn't seem so strange to you now. Maybe the Hindu gods don't seem so strange
00:20:31.840 anymore. By any measure, the planet should, the level four multiverse, is far stranger,
00:20:38.240 because it includes Yahweh and all the Hindu gods in every other set of gods you like,
00:20:41.920 who created our world, whatever the case. These multiverses are argued for on the basis of
00:20:48.960 fine-tuning. It's the only reason I ever see them being invoked, but aside from in philosophic,
00:20:54.640 purely philosophical discussions, but they only come into physics in this particular way by trying
00:20:59.920 to solve fine-tuning. But fine-tuning remains a problem still, because many physicists don't agree
00:21:06.400 with this particular solution. Quite right too, because as I say, it's not a good explanation.
00:21:11.440 I don't think this solves the problem. Most don't think this solves the problem by this
00:21:17.280 explanation. It's not a good explanation. It's too easy to vary, but in fact, so are the alternatives
00:21:23.280 to it. These multiverses, especially the number four multiverse, they're easy to vary. People will
00:21:30.160 vary on what is conceivable, or logical, or possible in that way, because they're not constrained
00:21:36.400 by physics. They're not even constrained by imagination. It may be level four consists of
00:21:41.760 the infinite class of logically possible universes, but just not the one where the electron has
00:21:47.520 doubled the value of what it does in our universe. I mean, that's a logically possible
00:21:51.520 multiverse, right? So that's easy to vary. Maybe they all exist except for that one,
00:21:56.160 although all exist except for that one, and where the electron has a charge of triple-hours
00:22:00.640 at infinite them, as I say. Anyway, there are at least two other competing theories for this,
00:22:07.120 okay? That's a wild claim. Every possible reality exists out there somewhere,
00:22:12.000 pretty wild claim. I think it's less wild, to be honest with you. It's less wild to
00:22:16.640 postulate the fact that a God created this universe, a God created this universe. Now, why is it
00:22:21.920 less wild? Well, because if every logically possible universe exists out there somewhere, that
00:22:27.200 includes universes created by gods, universes created by gods. So if you postulate every logically
00:22:33.200 possible universe, logically possible. Well, physically, logically possible, it's logically possible
00:22:37.760 that you can have all powerful beings there somewhere or other. It's a logical possible. I can imagine
00:22:43.520 that. If you can imagine it's logically possible, right? I don't see a contradiction in that.
00:22:47.520 Other people are going to say, oh, there's a contradiction. I can have, well, let's have something
00:22:50.640 less than an omnipotent, okay? But God-like beings are out there. For all intents and purposes,
00:22:55.600 God-like beings occupy that multiverse. So isn't it more parsimonious to just say, rather than
00:23:02.400 have an infinite number of God-like beings, let's have one God-like being that created this
00:23:07.120 universe. It seems more parsimonious. Anyway, so these are two of the competing clients. Now,
00:23:11.760 there's at least a third I know, which is that the physical laws here are by a friendly,
00:23:16.240 and we appear the way that we do because it's mathematically necessarily required, and whatever
00:23:22.320 the successor to quantum theory and general relativity is, or the successor to the successor of that,
00:23:27.440 will turn out to just have a set of equations which require, as a matter of mathematical necessity,
00:23:33.840 logical necessity, that the constants have the values that they do. And so if this is the case,
00:23:39.200 well, that rules out the planitude, the multiverse of multiverse is so to speak. We don't know,
00:23:44.560 but the way that the way that some popularizes, some people in this very conversation are talking,
00:23:50.880 it's as if that level 4 multiverse counts just as well as the level 1 multiverse,
00:23:55.120 and the level 3 multiverse. And I just don't think that it does. I don't think that it does.
00:23:59.040 We're not distinguishing between these different kinds of universes, multiverse is rather,
00:24:03.680 in the way that we should, what is known, not known to be true, but known as our best explanation,
00:24:08.800 known to be a good explanation of the observed facts, and what is just one of many competing
00:24:14.640 hypotheses that you would invoke a multiverse for, but there could be other solutions that rule
00:24:19.360 out that refute that multiverse. So again, a pick it up where Max begins to talk about inflation
00:24:25.680 theory, which is interesting. I'll have some things to say about what he says about
00:24:29.520 inflation theory here, and also his own sort of, well, walking back to a certain extent of
00:24:35.680 what this level 1 multiverse in scare quite happens to be. So let's do what Max has to say.
00:24:43.680 First it's a great illustration of one of the cool things in science, where you start with
00:24:48.480 some pretty innocent assumptions, namely here that space just goes on forever, like most of us
00:24:53.120 thought as kids, and moreover, the things started out a little bit randomly everywhere,
00:24:57.840 and you get this totally shocking conclusion. If when I go ask my colleagues, I'll say the vast
00:25:04.000 majority of them would put their money on that some form of inflation happened, and that our space
00:25:10.160 is actually much bigger than our universe, whether it's actually infinite or just really huge,
00:25:16.000 starts getting a little bit more controversial, and we would love to also, we also don't know for sure,
00:25:20.640 of course, whether inflation actually happened. But this is sort of the simplest version of the
00:25:27.680 theory, where space simply goes on forever. It's an infinite space, much like Euclid space,
00:25:33.280 or the one we thought about as kids, and in the book I call this the level 1 multiverse,
00:25:39.840 but you can just use this in them space for it, and just to drill down a little bit more and
00:25:45.920 where the craziness comes in. If you look at the way our universe got this way, and the way our
00:25:50.880 podcast came about, because we had about 10 to the power 78 quarks and electrons here that started
00:25:56.720 out in a particular way, somewhat random early on, after inflation, which led to the formation
00:26:02.880 of our solar system and our planet, and our parents met, and so on, and we met, and then this
00:26:07.280 happened, right? If you'd started the quarks out a little bit differently, things would have
00:26:11.280 unfolded differently, and you can actually count up how many different ways you can arrange
00:26:15.920 the quarks and electrons in our universe. And it turns out it's only about a Googleplex
00:26:20.480 different ways, where Googleplex is one where the Google zero is when the Google is one of the
00:26:24.720 hundreds zero. It's a huge number, but it's finite. So if you have an infinite number of other
00:26:31.280 regions equally big, and you roll the dice again, and all of them, then as you can talk to it,
00:26:38.720 that if you go about a Googleplex meters away, you will indeed end up with just what you described,
00:26:43.920 the universe that's extremely similar to this one, except that one minute ago you all of a sudden
00:26:50.080 you don't have decided to start speaking Hungarian instead.
00:26:53.680 So there's three things I want to say about what just being said there. The first is that
00:27:04.160 Max says that you can't know for sure about whether or not inflation is actually the
00:27:09.440 explanation of the beginning of the universe. And as we say here, well, if that's your standard
00:27:14.880 knowing for sure, then you won't know anything at all. Now, inflation is an interesting kind of
00:27:21.200 an explanation. I would say we know the Big Bang occurred, and I would actually also
00:27:26.880 tend in the direction of saying that we know inflation happened as well. I just don't think there are
00:27:31.760 any other viable competitors at the moment. We need to explain observations, observations of stuff
00:27:39.200 like the cosmic microwave background. Now the cosmic microwave background has this feature of being
00:27:43.440 exceedingly smooth, and what exceedingly smooth means is that when you map these slight
00:27:49.120 temperature variations in the empty space between galaxies, this is the cosmic microwave
00:27:53.840 background radiation, the heat left over, the residual heat left over from the Big Bang.
00:27:58.320 Well, actually, you look far and off into the distance to about 300,000 years after the Big Bang,
00:28:04.080 and you get this map, you get this map of the sky. This is what Kobe, the cosmic microwave
00:28:10.320 background explorer, and W map, the Wilkinson microwave anisotropy probe, and recently the
00:28:16.560 Plank telescope. These satellites are up there mapping this cosmic microwave background.
00:28:21.280 Whatever the case, what we find is that it's about 2.7 Kelvin. This is 2.7 degrees Celsius
00:28:27.040 above absolute zero. But there are fluctuations in the temperature, slightly warm in this region,
00:28:33.120 slightly cooler in this region. But those fluctuations are so small that the smallness of the
00:28:38.800 fluctuations cries out for an explanation, because the quantum cosmology say that well, when the
00:28:44.640 universe was smaller than an atom, then there would have been these fluctuations. The fluctuations
00:28:49.040 should have caused greater temperature differences. If you just rely upon classical Big Bang theory,
00:28:54.880 the regular Big Bang theory should have magnified these temperature differences. But instead,
00:29:00.080 we don't see these huge temperature differences. We see very small temperature differences.
00:29:04.960 So why they're small and not huge temperature differences? Well, inflation theory, inflation theory,
00:29:10.800 explains that. And we have no other explanation as far as I'm aware of why it is that we observe
00:29:17.040 what we do. So we've got this observation that cries out for an explanation and we have only one
00:29:21.520 explanation. Now, someone comes up with a rival, then we would need to have a crucial experiment
00:29:25.760 test that could decide between the theories, but we don't have any other theory. So the only
00:29:29.760 known explanation for why we're getting this smoothness in the cosmic microwave background,
00:29:33.840 amongst other things, by the way, amongst other things, you can go Googling or Wikipedia
00:29:37.600 inflationary cosmology, the inflation theory, which is just a version of the Big Bang theory.
00:29:42.400 And what you learn is that there are observations that are explained by inflation theory,
00:29:48.240 but not explained by anything else. And so this is important. So this is why I would say
00:29:52.240 it's quite right and reasonable to say we know inflation happened. As we know, the Big Bang
00:29:56.880 happened, as we know evolution by natural selection happens. These are the only known explanations
00:30:02.000 of the observations that we have. Do we know these things for sure? No. Again, if that's
00:30:06.560 a standard, well, you're always going to be disappointed in science and everywhere else.
00:30:10.240 Notice also that their max admits what I was complaining about earlier, which is that this
00:30:16.160 level one multiverse, not really a multiverse, he just says there, it's a synonym for space,
00:30:22.240 quite right. I think that's quite right that he should say that. But then he also says a thing
00:30:26.400 that I might quibble with just a little, which is that if we have this finite amount of matter,
00:30:31.040 but it can be rearranged into a finite number of different arrangements, nonetheless,
00:30:34.640 this means that because there's such a stupendous number of different arrangements that we could have,
00:30:39.200 that we would have all possible arrangements represented there somewhere other. I don't know that
00:30:43.920 that follows. I don't know that that falls out of the way in which the physics actually works,
00:30:48.800 unless of course you're talking about the ever radiant quantum theory where, yes, indeed,
00:30:54.000 there will be versions of you, versions of you that are very similar to you and versions of you
00:30:58.160 that are very different to you, but this idea of traveling physically through space to reach a
00:31:04.320 another planet, for example, where there's someone very similar to you there. I don't know that
00:31:09.520 that follows. We would need another physical law that mandates that all the different possible
00:31:15.040 arrangements really would be represented out there in deep dark areas of our universe somewhere
00:31:20.320 other. Now that spatially connected regions too, the one that we occupy here, I don't know that
00:31:25.840 it follows that you're getting something like the ever radiant multiverse here in our regular
00:31:31.280 physical universe, just at a great distance from us, which is what he's talking about here.
00:31:36.240 It could be, it very well could be that distant regions of the universe have subtly different
00:31:42.880 physical properties to what is had here because it just quirks of the big bang, for example,
00:31:47.680 quirks of the big bang could distribute the matter in different ways and so clump together in
00:31:53.120 different ways. And this would mean that not all clumpings are going to lead to what we see around
00:32:00.000 us in our region. They're model claps together into a black hole in some of these places.
00:32:04.240 It might spread out into a vacuous nothingness. There's nothing that says that the kind of multiverse
00:32:09.120 he's talking about here needs to represent all possible configurations of matter. That just might
00:32:14.800 not happen. Unless there's a physical law that says, well yes, this kind of thing happens,
00:32:18.240 but I know of no such physical law that mandates this is in the realm of the just the unknown,
00:32:24.320 just the unknown. It's a form of metaphysics as I say. It's a stepping outside of science. I don't
00:32:29.840 know how we could test this exactly yet yet. Let's keep on going.
00:32:35.280 It's a very mind-boggling idea. We don't know for a fact that it's like this, but this is the
00:32:40.640 sort of the vanilla flavor, the cosmological model, the one that is the most popular today.
00:32:45.920 Right. Right. Well, and I think the weak link in this chain of reasoning here or the place where
00:32:50.320 where a skeptical person can get off this train is in the assumption or belief that inflation
00:32:58.240 implies an infinite universe rather than just a very large one. It seems like you could pull
00:33:03.360 the brakes there, but unfortunately this concept of a multiverse judging from your discussion of it
00:33:09.360 in your book, and this is what I didn't understand before I picked up your book, seems over
00:33:13.440 determined. It seems there are other ways that are arriving at this multiverse concept, which we'll
00:33:18.080 get to, and so it has a scientifically speaking, there are many reasons to believe in a functionally
00:33:25.680 infinite number of copies of ourselves living out lives of, for all intents and purposes,
00:33:30.880 exactly similar or differing to every possible degree. Right. So it's true to say that everything
00:33:36.720 that can happen does happen under this rubric. That's right. So just to distinguish between what
00:33:43.040 we know and what we don't know for sure, the part that we don't know for sure is that space is
00:33:47.680 infinite, or that there's an infinite number of anything, and for people who feel really bothered by
00:33:52.480 these implications and want to get rid of the infinity. In fact, I have a whole section in the book
00:33:58.560 where I attack infinity and list all the ways in which you can get rid of the infinity.
00:34:03.040 So there's a lot of interesting opportunities there, and we're going to know more, I think, in the
00:34:06.960 next five or ten years. However, what I think seems pretty much inescapable at this point,
00:34:12.880 is that the full reality is at least much larger than what we can see. There's just no way
00:34:19.120 that space ends exactly at the edge of our universe. In fact, if you had made that claim,
00:34:25.360 you know, one minute ago, I could falsify it now by looking with a telescope because
00:34:30.080 I can see light that's traveled from one minute farther away, and that's pretty far,
00:34:34.480 that's a sixth of the way of the sun, an eighth of the way of the sun already, right?
00:34:37.600 And so we should probably get used to the idea that we live in a much grander reality
00:34:42.880 than we thought we did. And I think that's a good thing.
00:34:45.920 Yeah. Oh, yeah. No, so I don't think people's intuitions recoil at the very, very large,
00:34:52.080 or even I think people are prepared to embrace the infinite and the eternal, in some sense,
00:34:58.240 even though we could debate whether thinking about a beginning is actually more understandable
00:35:03.280 than thinking about an eternal universe, given how squirrely the beginning begins to look.
00:35:08.320 But I think what really will blow the mind of anyone who thinks about it long enough,
00:35:13.840 and seems very difficult to accept, is this idea at the level one multiverse,
00:35:20.720 what is implied by just the sheer concept of infinity, that everything that is possible
00:35:26.800 is, in fact, actual on some level. Everything is true. And let's just spell out why this should
00:35:33.120 be disturbing and why this may, in fact, be at least at first glance a real embarrassment to science,
00:35:39.600 because it's science prides itself on being parsimonious.
00:35:47.040 Well, no, it's not the case of the level one universe in any way, shape or form,
00:35:52.240 says that everything that's possible is true. I don't get that, that everything is true in
00:35:57.600 some way. In fact, I think he said, there's an ambiguity about what that would mean anyway.
00:36:01.840 Do we mean everything that's physically possible is true or everything that's logically
00:36:05.600 possible is true? Well, I can't mean the last thing, which is the level four multiverse.
00:36:10.080 So the level one multiverse, which is just space, even if space was infinite, even if space was
00:36:16.240 infinite, that doesn't even imply that everything physically possible would be true.
00:36:20.320 It doesn't imply that at all. I could readily imagine an infinite space where we occupy a region
00:36:26.240 which is different to the rest. You need to have a particular kind of what's called the cosmological
00:36:31.520 principle, which says that there's nothing particularly special about our particular region of space.
00:36:36.080 But we, if we don't have access to these are the regions of space, these are the infinite
00:36:41.120 region of space. We could easily postulate other regions of space, which are empathy, for example.
00:36:46.720 You'd still have infinite space. We could have any infinite space beyond what we can see that
00:36:52.080 is filled with nothing but hydrogen nuclei, which is protons. There would be basically a
00:36:57.280 featureless universe. But the thing is, if we can't observe, and if we don't have good explanation
00:37:02.400 of, at this point, what this infinite space is like, then you're just postulating a particular
00:37:09.280 metaphysics once again, saying that somewhere often this infinite space, there must be every single
00:37:15.920 physically possible thing represented there in some way, shape, or form. But I don't see that that
00:37:20.160 follows. If all you're saying is, it's an infinite space. Even if you said it's an infinite
00:37:25.360 space like ours, that doesn't mean that you're going to eventually get an earth just like ours
00:37:31.040 here. You have to add extra assumptions to this idea. The extra assumptions being, well, you've got
00:37:37.600 the same kind of distribution of matter out there in infinite space. But that's a very specific
00:37:43.600 assumption that you're making. It's ruling out all the ways in which you don't have the same
00:37:49.040 distribution of matter elsewhere. There's something very special about the earth after all,
00:37:53.520 just I mean, look around, it's unusual. The universe, vast as it is, may only contain one earth,
00:38:00.240 may only contain one earth. Of course, infinity tends to sort some of these things out for you.
00:38:05.120 But the level one multiverse, I'm not so sure, not so sure. And certainly it does not imply,
00:38:11.280 it certainly would not imply, or logically possible realities out there somewhere. That certainly
00:38:16.240 doesn't follow. Okay, Sam and Max then go on to talk about Passimani, okay, which is basically
00:38:23.440 Occam's razor. This idea that all else being equal, we should choose the simplest explanation.
00:38:28.960 This was why when I asked Professor Paul Davies, why didn't he endorse the multiverse? Do you ever
00:38:35.360 write in multiverse when I had the chance to talk to him about this? He appealed to Occam's razor.
00:38:39.360 He said, well, in order to explain the one universe we do observe, we're invoking the existence of
00:38:44.000 an infinite number that we can't observe. And at the time I bought it, of course, now I realize,
00:38:48.000 no, Occam's razor is about the number of independent assumptions that you have. And, you know,
00:38:52.880 the multiverse, the ever written in multiverse, has no real additional assumptions being added on
00:38:57.840 to the formalism of quantum theory. It's just saying, well, take the equations seriously, take
00:39:03.520 them literally, take the results of the experiment seriously. And this is all you get. You don't
00:39:07.840 need to add anything about consciousness in the observer or anything else. Everything just obeys
00:39:12.320 the same physical laws. And so, therefore, you have these, you have all matter obeying the
00:39:17.360 same physical laws. And the equations describe the existence of these other things. And then
00:39:22.640 also explains why you won't observe these other things. You can't communicate between
00:39:26.240 universes, for example. So, they quite rightly point out that passimity or, you know,
00:39:32.400 recourse to the simplest theory, Occam's razor, whatever you want, however you want to describe this,
00:39:37.120 is not a reason to object to multiverse theories in general. And certainly not a reason to object
00:39:43.680 to the ever-written multiverse. But once again, they're kind of dancing around the ever-written
00:39:47.680 multiverse. I never get there and talk about quantum theory, which is the shame that the one
00:39:54.240 really interesting by virtue of the fact of being an explanation that is unusual. But also, so far
00:40:01.520 as we can tell, it's the correct one. It's the right one. So, I'm going to skip through all of that
00:40:05.440 because I think listeners to talk cast readers of the fabric of reality, for example, know about
00:40:11.200 Occam's razor and passimity and this kind of thing. Let's press on into the multiverse to
00:40:19.520 level two. We'll push people's intuitions in the direction of feeling like,
00:40:26.240 at the very least, we're trying to have our cake and either two on this question of parsimony.
00:40:30.400 So, take us to the level two multiverse and perhaps say why this is relevant to the question of
00:40:39.840 fine-tuning and the question of fine-tuning, as many people will recall, is relevant to this
00:40:46.240 idea of that many religious people have of why religion, the idea of a creator god in particular,
00:40:52.880 makes sense given the apparent fine-tuning of our universe.
00:40:56.160 But pleasure. So, the level two multiverse, you can again,
00:41:01.440 synonymously called simply space, if you want. Inflation is able to actually not only make
00:41:07.840 an infinite space, but it's actually able to make fit within this, an infinite number of regions
00:41:14.320 that each seem infinite to whoever lives inside of them through some very, very weird properties
00:41:21.200 of Einstein's gravity theory that I talked about in the book. What's interesting about this
00:41:26.400 is that when you ask how diverse is space, you might think, oh, you know, in some places,
00:41:35.840 our podcasts goes like here and other places, we talk about other things, but at least the laws
00:41:40.640 of physics are the same everywhere. You might think, at least, even if we learn people learn different
00:41:46.080 things in history class, if the Sam Harris somewhere else learns different things in his history
00:41:50.720 class, because the quark started out differently there and history played out differently,
00:41:55.040 but at least he's going to learn the same thing in physics class. But the level two multiverse
00:41:59.120 changes that also, because it turned out that a lot of things that we thought were fundamental
00:42:04.640 laws of physics, that were true everywhere in space, were actually not, it seems.
00:42:10.640 And I like to think about it as if I were a fish swimming around in the ocean,
00:42:15.920 I would think that it's a law of physics. The water is something you can swim through,
00:42:20.560 because that's the only kind of water I know when it seems to be that way everywhere I look.
00:42:25.040 But if partish, I could solve the equations, discover the equations for water, and I could
00:42:30.080 solve them and see that there are actually three solutions, not one. There is the water solution
00:42:35.040 and also ice and steam. Equivalently, there are a lot of hints now in physics that what we call
00:42:41.200 empty space is also like that, that it can freeze and melt and come in many different variants.
00:42:47.600 And the thing is inflation is so violent that if space actually can be in many different forms,
00:42:54.480 what inflation will do is it will create each of those kinds of space and an infinite amount
00:42:59.840 of it that that. So if you go really, really far away, you might find yourself in a part of space
00:43:06.160 where there are not actually six kinds of quarks, like there are here, but maybe there are 10 kinds
00:43:12.320 of quarks. So the level two multiverse is very, very diverse. Also a lot of things that we learn in
00:43:18.000 school are fundamental parameters of physics. For example, the number 1836 seems kind of hardwired
00:43:26.160 into our world in that that the proton is 1836 times heavier than an electron. Why is that?
00:43:34.560 Well, string theory suggests that actually that's one of those things that also changes depending
00:43:40.000 on what kind of space you have. So it might be 2015 somewhere else in 666 somewhere else.
00:43:47.840 And this explains this fine tuning problem that you mentioned because we've discovered,
00:43:52.400 as I alluded to earlier, that there are these 32 numbers pure numbers with no units or anything
00:43:58.640 that we've measured that we can use to calculate everything else. And we wonder a lot of
00:44:03.280 where they came from. So these are the constants of nature. Could you just list a few of them to
00:44:08.320 give people a sense? Yeah. So 1836 is one of them. How much heavier the proton is in a neutron.
00:44:14.400 You can transform them in different ways. Another one which is super talked about these days is
00:44:18.720 that the density of dark energy. Okay. So as I explained in episode one of my discussion of their
00:44:29.200 discussion, the level two multiverse is a version of the multiverse where it's presumed that the
00:44:36.400 initial conditions are somewhat different. And indeed, the constants of nature are somewhat different.
00:44:41.760 And this arises out of, as Max explained there, versions of string theory. Now we don't know,
00:44:48.720 this is a kind of metaphysics as to whether or not such universes exist. But we're still within
00:44:54.320 the realm of, although he insinuated there that the laws are physically different, not really,
00:45:00.000 we still have, although we might have different numbers of quarks in these other universes,
00:45:03.760 we still have quarks, for example. We're still bounded by what string theory says as possible.
00:45:09.040 So we're not yet in the realm of all logically possible universes. We're not there yet.
00:45:13.440 But we are saying, well, you can vary the constants of nature, let's say, but we still have
00:45:17.760 constants of nature. Those constants of nature still exist. And so perhaps we can explore the space
00:45:22.480 of all different constants of nature. Now, this is actually done by some people. Some people,
00:45:26.880 this is their job cosmologist Luke Barnes, who is easily found on Twitter is one of the people I
00:45:32.400 follow on Twitter. He's a cosmologist at the University of Western Sydney. He works with
00:45:37.600 Grant Lewis, who is an astrophysicist at the University of Sydney. They've written books on this,
00:45:42.480 whatever it is, at least one book called, A Fortune at Universe. Now, there have been many books
00:45:47.360 written on this idea of fine tuning. Some people disagree with fine tuning. I buy it as being a
00:45:53.840 problem. Why is it that we inhabit a region of space where the constants are what they are? We don't
00:45:59.040 know yet. And as I've already explained, it could be, it could be that we have this multiverse of
00:46:05.200 universes where all the different constants of nature are out there represented somewhere or other.
00:46:09.280 Okay, that could be the case. And we, of course, occupy the one where the constants are just right.
00:46:14.240 There are many other universes kind of like this as well. Well, the work of Luke Barnes,
00:46:18.640 among others, sort of suggests that this fine tuning is very, very fine tuned. And we need
00:46:24.640 an explanation for this. Many people say, we don't need an explanation for this. Now, Barnes
00:46:29.680 for one thinks that it's a very poor explanation to say, well, it's the multiverse that explains this
00:46:35.760 stuff. And I'll give a link in the information for this podcast and for this episode,
00:46:41.760 to his material on this. He does some wonderful lectures. He's also been on closer to truth,
00:46:46.800 which is probably my favorite YouTube channel out there. He's been interviewed there. He's
00:46:51.920 an Aussie. And so he has this to my mind anyway, rather clear way of speaking about this stuff.
00:46:58.560 And no nonsense sort of way of speaking about this stuff. He's had debates with people like
00:47:03.040 Sean Carroll. And he's had debates with people like Sabine Hossenfeld. So, you know, he's talking
00:47:08.960 to some of the big names out there about all of this stuff. And he really knows his stuff. I mean,
00:47:13.600 he's really across this. And he does things like simulates entire universes in supercomputers to
00:47:19.680 see what happens when you alter these constants of nature, just to see what happens.
00:47:23.360 So it does seem like there's a problem there. Certainly one of the things that I was most
00:47:27.760 interested in exploring when I was doing formal studies in astronomy and cosmology was looking
00:47:32.560 into this issue of just how fine-tuned the constants of nature are. Could you change them
00:47:38.000 very much at all? And well, it turns out you can't change them very much at all.
00:47:42.960 Just the smallest changes to things like the value of the gravitational constant, the strength
00:47:48.000 of gravity, or the value of the mass of the proton, these kinds of things, either could
00:47:53.600 changes in these kinds of things, either cause all matter in the universe to collapse into black
00:47:59.280 holes. And so you don't get any stars, therefore you don't get any planets. Or cause a universe
00:48:04.480 where the gravity isn't strong enough in order to collapse matter into stars at all in the first
00:48:10.240 place. And so all you're left with is clouds of hydrogen and helium gas. So you'd have no life in
00:48:15.120 such a universe there either. So that's just a few of the constants. Now, that's for all the
00:48:18.560 other constants. Well, you can have changes in cosmological constants that cause a ripping apart
00:48:22.880 of space time very early on in the universe. Or even just after the big bang you get an
00:48:26.960 immediate re-collapse into a big crunch kind of thing. So this is a very interesting question,
00:48:32.320 open area of research. We don't know much yet. And so this is what they're talking about here
00:48:37.360 with this kind of level two multiverse that may be all the different constants of nature
00:48:41.680 are out there being explored somewhere other. But they're still bound by the basic laws of physics.
00:48:46.960 These universes are obeying different versions of screen theory. That's one thing. So they're still
00:48:51.760 obeying a certain kind of explanation. Unlike the level four, one is I keep mentioning where
00:48:58.160 you're having every single kind of physical or being. So I forget string theory, that's just
00:49:03.120 one tiny sliver of all the possible physical laws that you could have, which is what the level
00:49:08.480 four one is. But in either case, do we know, as in to say, we have a good explanation of this as
00:49:13.920 being an account of reality, a reality that we inhabit. So let me skip towards the end of their
00:49:19.760 discussion on the multiverse. If it's infinite, just suggests that everything that happens,
00:49:27.440 that can happen within the laws of physics does happen with the level two we're talking about
00:49:33.520 inflation creating an infinite number of bubble universes, which wherein the laws of physics
00:49:40.000 themselves vary in every conceivable way. And we not just interject. So it doesn't sound too weird.
00:49:49.200 Instead of talking about bubble universes, we can just keep saying space because there's still
00:49:52.960 only one space. But it's not space in a straightforward sense that it is actually, but the
00:50:00.400 reason, the reason we can never get to another part of the level two multiverse is because
00:50:06.000 in order to go there, you would have to go through a region of space or just still inflating
00:50:10.720 and stretching out. So if you have your kids in the back seat asking, are we there yet?
00:50:17.200 You know, you would say, oh yeah, we'll be there in one hour. And then a little bit later,
00:50:21.440 they ask, are we there yet? And you'll be there in two hours. So inflation can actually create
00:50:27.680 this funny situation where you have many even infinite regions of space that are still fitting
00:50:33.600 into one single piece of space. So that's one clarification. It's still just this one space,
00:50:38.480 but messy. And the second thing is it's not that the actual laws of physics are different.
00:50:43.120 It's just that things that we thought were laws of physics turned out to actually just be
00:50:48.240 different solutions to the laws of physics. Exactly. Ice is not the different law of physics
00:50:53.120 from liquid water or steam. They turn out to be three different solutions to the equations for
00:50:58.480 water. And that's something awesome would like because it makes physics itself simpler and it
00:51:03.280 makes history more complicated. That's a fascinating idea. And it is one that closes the door
00:51:09.040 to this otherwise embarrassing problem of fine tuning, which is how is it that we find ourselves
00:51:16.320 in the universe that seems perfectly tuned to support life and intelligent life and beings
00:51:23.120 exactly like ourselves in a position to wonder about these things. And there have been other
00:51:27.040 efforts to close that door just with what's been called the the anthropic principle, which you
00:51:31.200 stated earlier, just that the only place we can find ourselves is a place that's compatible with
00:51:36.160 our existence. And so that shouldn't be surprising. And yet it has seemed surprising that
00:51:42.240 essentially that we should exist at all that the universe could have been an infinite number
00:51:46.400 of ways. And it just happened to be this way. Well, in according to the level two multiverse,
00:51:53.200 the universe is essentially an infinite number of ways. And there are an infinite number of
00:51:58.560 universes that are not compatible with life. It's kind of a Darwinian principle of universe
00:52:03.600 emergence that the only places you can find yourself or the places you you can find yourself
00:52:08.480 and every place that is possible in some sense exists. Yeah, I don't like the use of the term
00:52:15.760 anthropic principle for these sort of things. The word principle makes it sound like it's somehow
00:52:19.680 optional. I mean, it's just a reduce of logic, which of course is not optional. You know, the
00:52:25.200 like why are you really, really surprised that out of all the eight planets in our solar system,
00:52:30.720 we're living on Earth rather than Venus, where it's 900 Fahrenheit right now, or on Jupiter,
00:52:37.520 where there's no surface is that on? Probably not very surprised. I wouldn't call that in deep
00:52:42.240 principle. It's just common sense that the vast majority of our solar system is not very friendly
00:52:48.480 for our kind of life. And the vast majority of space is horrible for our kind of life.
00:52:55.440 And therefore, we shouldn't be very surprised that we're living in a special very,
00:52:59.360 a very special part of the space that we can see. It is kind of a place that we're living in
00:53:05.360 a special part of the space we can't see either. So one way of closing the door to this mystery
00:53:10.640 of fine tuning, which doesn't entail yet another multiverse, so a level two multiverse,
00:53:17.840 is this idea that we could be in a simulation. I don't know if this argument originates with
00:53:23.200 your friend Nick Bostrom, or if other people have arrived at this independently.
00:53:30.160 But the argument is older, but Nick Bostrom made it a very detailed argument for why we
00:53:35.520 think it's actually likely that we live in a simulation.
00:53:38.080 Right. So yeah, so I guess we can open the door to that too. So his argument in brief is that
00:53:44.560 if you imagine ourselves in the distant future, or beings like ourselves that make vast
00:53:51.280 gains in their ability to produce computers, and it stands to reason that they will simulate
00:53:57.520 universes and beings very much like ourselves on those computers, assuming that such a thing is
00:54:02.880 possible, and there's really no reason to think it isn't. And then by just dint of numbers,
00:54:08.160 you would expect simulations to vastly outnumber real universes, and therefore you would expect
00:54:13.440 that you should be in a simulation rather than in a real universe. That argument sort of stands on
00:54:18.160 its own unrelated to this issue of fine-tuning or the multiverse. But if taken seriously,
00:54:25.600 the prospect of being in a simulation, it does answer this fine-tuning argument as well.
00:54:33.840 So I always want to ask of the simulation hypothesis, what problem does it solve?
00:54:38.640 I don't know that it solves this fine-tuning is yet another one. It's just an appeal to the
00:54:43.040 supernatural. But, but if we do live in a simulation, then that will be revealed to us eventually.
00:54:51.840 People might say, oh, how could it possibly? Well, we would get to a point where a problem would
00:54:55.760 arise that would require us to postulate something outside of the simulation. A simulation won't
00:55:02.000 necessarily have infinite complexity. In fact, nothing can have infinite complexity, but reality
00:55:06.880 itself. David Deutsch argues this in the fabric of reality. A simulation has to be running on a
00:55:13.200 computer, which presumably is in a genuine physical reality of some kind, computing stuff, obeying
00:55:20.880 the laws of that universe. But the computer that the simulation is running on will have
00:55:25.920 finite memory, finite processing speed. And so we would get to a point where we'd be
00:55:33.040 delving into subatomic particles. What we think are subatomic particles and just get to the point
00:55:38.080 where we realize or we resolve the individual bits. And this would be telling us to, if we got to
00:55:45.600 the end like that, an endpoint like that, then we would have to ask why. And if there was no
00:55:50.160 such answer, we'd have to postulate that this reality exists in another reality, namely a simulation
00:55:56.000 type thing that is causing it to resolve into these fundamental things which can't be broken down
00:56:01.760 any further. I can't imagine what that would be like exactly. But there would come a wall before us
00:56:07.520 when it comes to progress. And that would cry out for an explanation. An explanation that
00:56:13.840 couldn't be within the universe, because the universe after all at that point would be bounded,
00:56:18.320 it would be this wall. But we could then ask the question, what's outside the universe,
00:56:22.560 because we'd get to the end of it in some way. Well, I don't mean the end of it in space
00:56:26.000 necessarily, although that could be a possibility as well. But the end in some way to us resolving
00:56:32.720 stuff, finding solutions, in particular, the smallest particles of matter, there would be a
00:56:38.800 smallest particle of matter or something the equivalent of that, some problem would just get solved
00:56:45.440 and there would be no way of moving beyond that, no way of making progress unless we postulate
00:56:50.960 something smaller still, but there wouldn't be something smaller still. It would be a strange
00:56:55.920 reality to occupy. So we would find out we would be able to find out we're in the simulation.
00:57:00.720 We would postulate the existence of something else, on which this simulation is running.
00:57:05.520 And it doesn't solve anything anyway. I mean, because the simulation hypothesis still
00:57:09.520 postulates a fundamental actual reality. So saying we're in a simulation is just to say we're in a
00:57:14.960 thing that's in physical reality. Or in a thing that's in a thing that's in physical reality. It
00:57:19.040 doesn't deny the existence of physical reality. And the simulation hypothesis still postulates
00:57:24.640 just more stuff in physical reality. That's all. And the physical reality is something different to
00:57:29.920 what we think it is. But it doesn't mean it's completely and utterly inaccessible. Why? Because we've
00:57:34.400 got universal minds. So we can always guess at what's outside. And perhaps do tests and get
00:57:40.000 sick, find way to know is the creative people of the future if we do live in a simulation would come
00:57:44.560 up with ideas about how to test this kind of stuff. Anyway, naval gazing I would say is this kind of
00:57:50.960 thing. It doesn't solve any problem of ours right now. I was talking about the simulation
00:57:55.600 hypothesis before. So I'm going to skip past what Simon Mac say on this point.
00:58:02.880 So this might be a good bridge. And now I'm mindful of your time here. So we're not doing anything
00:58:09.520 like justice to the contents of your book. We're going to skip over the other ways in which you
00:58:15.200 can arrive at a conception of a multiverse, in particular the quantum mechanical issues addressed
00:58:20.480 by Hugh Everett and all of that is fascinating. And it's just another route into infinite
00:58:27.040 copies of ourselves having infinite versions of this podcast and no doubt in some of those
00:58:32.320 podcasts. We treat these topics at much greater length. But I think this is a good bridge to AI
00:58:39.120 where which is where you and I met. Okay. So there we go. And I would say, unfortunately, unfortunately,
00:58:49.920 Max doesn't get to explain the ever ready in view of the multiverse. I'd like to hear how
00:58:54.720 other people explain that particular good scientific explanation. Yes. Max's book is worth getting
00:59:03.120 on this point. But like Sean Carroll, I think that he mistakes the testability of the multiverse,
00:59:11.200 the ever ready in multiverse, which David Dorch, of course, written a paper on. So here at the end,
00:59:16.800 I think it's important just to make some concluding summary remarks. Max Tegmark is of course
00:59:23.600 a great thinker, a very good physicist, highly accomplished, and a clear writer of some fascinating
00:59:30.560 topics. However, having read the mathematical universe and having heard a couple of interviews with
00:59:36.080 him, what I find is that there is a certainly a difference in epistemology. Let's just say that
00:59:43.280 between a perspective that David Dorch presents in the fabric of reality and the beginning of
00:59:48.880 infinity and what you get in something like Max's book, our mathematical universe. And I am going
00:59:54.880 to read a little just a very short snippet from his book, just to give you a taste of what I mean
1:00:02.240 about this difference between epistemologies and how it comes to affect something like the physics
1:00:09.280 and the conclusions. And importantly, what I would say is the metaphysics, the broader reality
1:00:14.480 within which one's physics sits. One's way of understanding just reality at the broadest possible
1:00:21.120 scale. I think this is why having a good understanding of some epistemology at least clarifies things
1:00:29.520 because two misconceptions tend to creep in. The one is as you would have heard when Max speaks there
1:00:35.840 and Sam can tend to do this sometimes as well, is that they make a dividing line between knowing
1:00:42.400 and knowing for sure. So he said that phrase at least twice that I recall in the recordings that I
1:00:49.360 made of that discussion. He would say, it's something we don't yet know for sure, but we can't
1:00:56.400 know for sure. Yet he implies we can, but how do we know for sure? We either know something or we
1:01:03.440 don't know something and that's that. We can just say of these multiverse theories. Yes, we know
1:01:09.200 that's the good explanation of what's going on or we don't know yet yet. And I would say that for
1:01:17.120 what he's calling level one, absolutely we know. It's part of our knowledge. This is predictive,
1:01:23.520 it's explanatory, it describes what's going on out there in the universe. It is the universe. It is
1:01:28.800 just our explanation of spaces we understand it. And the level three multiverse, yes, we know it,
1:01:35.680 we know it as the explanation of what's happening in quantum theory. So I agree with Max, possibly
1:01:41.440 for different reasons, but I agree with Max for that reason. Although perhaps we also differ on things
1:01:47.520 like whether or not we know once and for all, we know for sure that these things are true. I would
1:01:54.480 just say we know them. The appending of for sure is a superfluous unnecessary. In fact, it reduces
1:02:03.600 the meaning of know to something that means it's useless kind of a word because you never reach
1:02:08.960 this for sure bar. But Max does conflate the two at times, no one to know for sure. He wants to say
1:02:15.680 it can't be known until it's known for sure. And it's the sure part that makes it known,
1:02:19.920 and sure means certain, but how can we be certain? The history of science is enough to give us
1:02:24.480 fallibleism. The overturning of previous theories that people, many people, were certain of at
1:02:30.320 the time. And you also hear throughout the discussion, Max making quite a point about this unobserved
1:02:37.680 stuff being a part of science and Sam agreeing as well. And of course, I agree. And David Deutsch
1:02:43.200 agrees that the unobserved is absolutely a part of science, but proper continues to be denigrated
1:02:48.480 in some way, as if poppers epistemology implies that the unobserved is not accounted for because
1:02:56.000 it's not testable within his conception of reality, which is completely wrong. In fact,
1:03:01.840 popper is the only one who is able to explain how, via David Deutsch, I would say, that we get
1:03:09.440 to acknowledge of the unobserved through our theories via our observations when you're an empiricist,
1:03:16.880 which so many people are, they say that we'll knowledge is derived from what you observe.
1:03:22.320 And so you're stuck within what you observe. But it is difficult to get a handle on exactly where
1:03:28.480 Max is coming from in constructing knowledge as such. I can't find references to him describing
1:03:36.160 himself as a Bayesian, and certainly he doesn't make a big deal of it in the indices of his books,
1:03:42.400 let's say, you can't find the word Bayes or Bayes in isn't there. However, you do find claims that
1:03:49.040 he believes his theories. He says as much. This is completely unlike what popper implored us to do,
1:03:55.680 or what physicists like Michael Faraday thought. Michael Faraday said something to the effect of,
1:04:00.480 I hold my theories on the tips of my fingers, so the mirrorist breath effect will blow them away.
1:04:07.840 So he understood testability. He understood that you can have your theories all day long,
1:04:12.080 but once the observation comes along and it refutes your theory in light of a better theory,
1:04:16.720 we'll so much for having believed your theory, because I need to believe your theory.
1:04:21.520 Scientists shouldn't believe their theories. It's the wrong epistemologist, the wrong way of going
1:04:26.720 about science. Science explains the world. Through misconceptions, we say misconceptions,
1:04:32.960 because we should expect their theories to contain some error, not to be the final word on things.
1:04:40.400 And because there's an error there, there will be fixed one day overturned and we'll look back
1:04:45.200 and go, well, that was a misconception. Useful as it was to solve problems and getting something
1:04:51.280 right about the world, saying something correct, something true, containing truth,
1:04:56.560 an explanation, but nonetheless ultimately in the final analysis false and misconception.
1:05:02.240 So why believe it? Why think it's true? What does this word belief mean in this sense? What
1:05:08.800 function does it serve? Once one begins believing things, one ceases to be a fallibleist.
1:05:15.760 But then, of course, at other times, Max says that we don't know for sure, so it's hard to know
1:05:21.200 exactly where he's coming from. It's not a consistency there in the book. I've just released
1:05:27.520 a podcast called Lookouts, and it's about worldviews. And it says why having a worldview,
1:05:34.880 which in other words I would say, not only a rich deep foundational understanding of the science,
1:05:42.240 but also having an understanding of what metaphysics is, ontology, epistemology, and how these things
1:05:50.640 relate to everything else, science, physics, mathematics, and how all of this can come to bear on
1:05:58.400 broader, even more important things, perhaps like morality. And having a conception of all of
1:06:03.440 these things that is encompassed by a philosophy of how to make progress, how to understand the world,
1:06:10.640 and that we don't get to final answers. And the problem with thinking that one can get to
1:06:15.600 final answers rather than simply improve continuously over time. And it's going to read an excerpt
1:06:22.160 from page 880 from our mathematical universe. This is chapter 12. It's also a big tone, all about
1:06:28.960 the different levels of multiverse. And he says, this is Max Tegmark speaking, quote,
1:06:33.600 interestingly, in the context of the mathematical universe hypothesis, the existence of the level
1:06:40.080 four multiverse isn't optional. As we discussed in detail in the previous chapter, the mathematical
1:06:46.160 universe hypothesis says that a mathematical structure is our external physical reality,
1:06:52.400 rather than being merely a description thereof. This equivalent between physical and mathematical
1:06:58.960 existence means that if a mathematical structure contains a self-aware substructure, it will perceive
1:07:05.840 itself as existing in a physically real universe. Just as you and I do, albeit generically,
1:07:11.680 a universe with different properties from ours. Stephen Hawking famously asked,
1:07:16.480 what is it that breeds fire into the equations and makes a universe for them to describe?
1:07:21.920 In the context of the mathematical universe hypothesis, there's no fire breathing required
1:07:28.320 since the point isn't that a mathematical structure describes a universe, but that it is a universe.
1:07:34.480 Moreover, there's no making required either. You can't make a mathematical structure.
1:07:40.880 It simply exists. It doesn't exist in space and time. Space and time may exist in it.
1:07:46.960 In other words, all structures that exist mathematically have the same ontological status,
1:07:53.040 and the most interesting question isn't which ones exist physically, they all do end quote.
1:07:59.520 So as I say, that's from chapter 12. And it's from a section in chapter 12, the title of which
1:08:06.720 is, and I'll read you the title. Why? I believe in the level four multiverse.
1:08:12.720 So I think that that's just a departure from science, I'm afraid to say.
1:08:18.080 It's somewhat a departure from rationality. He calls what he's doing, the mathematical
1:08:24.640 universe hypothesis. Yet he says he believes it. Why? What is the rational reason? We're not
1:08:32.160 given one. We're told that all mathematical structures just exist. Now this is confusing necessary
1:08:39.600 truth with our knowledge of the necessary truth. He's saying that he's gotten to the ultimate
1:08:47.200 final truth. And that truth is that the entire universe consists of mathematics. In fact,
1:08:52.240 there are an infinite number of universes out there that are made of mathematics.
1:08:58.960 But what privileges mathematics? What makes the difference between the abstract mathematical
1:09:06.000 objects and the abstract any other objects, the difficulty for Max fundamentally is that he cannot
1:09:13.920 get outside of his physical brain. Now he argues in a circular way. He says that everything is
1:09:20.480 mathematical. It's Pythagoras' idea. All is number. He begins with that assumption and then
1:09:26.880 reaches that conclusion in the end as well, rather than starting with problems. For example,
1:09:33.600 what is the brain figuring out? Well, okay, the brain is made of neurons. What are neurons
1:09:38.560 matter? They're made of atoms. Okay, that's a form of matter. What are the laws that matter
1:09:43.200 must obey? Quantum laws of physics. Are the quantum laws of physics computable? Indeed, they are.
1:09:49.680 Indeed, all physical structures undergo physical processes themselves which are
1:09:55.200 computable. And that includes brains. That includes brains that do mathematics to come to an
1:10:01.360 understanding of mathematics. However, what we also understand via this process,
1:10:06.560 by this understanding of computational universality, is that computers can introduce errors.
1:10:12.320 They're not perfect machines. They can error correct. But there's no getting around the fact
1:10:16.800 that it could be the case that a mistake is made at any point during the explanation, the
1:10:21.840 computation, the calculation, however you want to put it, a neuron can misfire. An electron can go the
1:10:26.720 wrong way. A person can just make a mistake. And that cannot be escaped from. And that includes
1:10:33.600 any conclusion reached by that brain. Well, mind, we should say. And that includes
1:10:40.160 minds that come to the conclusion that, for example, everything is made of maths,
1:10:44.880 that everything consists of mathematics. And therefore, level four multiverses exist that
1:10:50.640 necessarily exist must exist. But this has all been arrived at via a brain obeying the laws of
1:10:58.000 physics, a via something we know, we know, we know that. And so we know that it can't be the case
1:11:04.800 that we can simultaneously know, for sure, that the mathematical universe exists as in the
1:11:13.200 mathematical multiverse that Max Tegmark says exists. So what I'm sad to say is he is ignoring
1:11:20.000 known science. It's true for him to say it's a mathematical universe hypothesis.
1:11:25.600 But it is a rational for him to say that, therefore, he believes it. A scientist shouldn't believe
1:11:31.040 their own theories, even when they're known, when they are the best explanations. But in this case,
1:11:36.960 we don't even have a known theory. It's not even a good explanation. It's just one explanation among
1:11:42.640 many among many to solve certain problems. Those problems I've already mentioned are just things
1:11:48.240 like the fine tuning issue, the fine tuning problem. What Max wants, and this has been true
1:11:54.800 across the eons, is a certain foundation that explains absolutely everything once and for all.
1:12:02.400 It's a kind of religious notion, this idea that, you know, God created everything and that,
1:12:07.920 you know, the ultimate answers are held by God. And there's nothing beyond that. Well,
1:12:12.640 the mathematical universe, especially the level form multiverse, is that structure. It is that
1:12:17.760 thing. It serves that purpose. It answers all questions. Let's just go on a little further. I'm
1:12:23.040 not just read from page 959 of his book. And he says, quote, the level for multiverse does not
1:12:29.840 imply that all imaginable universes exist. We humans can imagine many things that are mathematically
1:12:36.160 undefined. And hence, don't correspond to mathematical structures. Mathematicians publish papers
1:12:42.640 with existence proofs that demonstrate the mathematical consistency of various mathematical
1:12:47.760 structure descriptions precisely because to do this is difficult and not possible in all cases
1:12:53.200 end quote. Elsewhere when Max writes on this, he does speak in terms of all conceivable things
1:12:58.720 exists. If you can conceive it, then it exists. But now he's saying that not all imaginable
1:13:04.880 universe exists. Maybe what he means, or should say when you speak in more carefully, is that
1:13:08.720 all conceivable mathematical structure exists out there somewhere other. But has I also pointed
1:13:14.000 out during this podcast in other universes with different laws of physics? If there are people
1:13:20.560 in those universes with different laws of physics, then they are able to prove different things
1:13:26.400 about different mathematical structures. And so their conclusions that they reach about this
1:13:31.200 level form multiverse, if it exists, would be different to ours. So whatever he's saying about
1:13:36.560 the level form multiverse here, by his own reckoning, should be different in other parts of the
1:13:42.640 level form multiverse. So what do we say? Whose level form multiverse is it? Is it constrained
1:13:49.440 by the mathematics that's known here or known there? Or rather provable here or provable there?
1:13:56.160 We can't say. It's not easy to know. I don't know if the question is well defined either.
1:14:02.160 It's true to say that logic is logic is logic and mathematics is mathematics is mathematics or
1:14:06.480 godless of where you are. But assertions about what mathematical structures exist based on what
1:14:13.200 human brains can do, trying to reach conclusions about places where the physics is,
1:14:19.840 places where the physics is so different. But what can be understood by mathematics is literally
1:14:25.440 literally inexplicable to us because our brain simply is unable to rock stuff that brains
1:14:32.320 presumably are buying completely different laws of physics that are able to rock. Well, we're
1:14:36.480 getting into the intractable area of metaphysics and fantasy. So it's a very difficult talk about
1:14:41.440 these things. And this is why it would be strange for me to hear someone say they believe this
1:14:47.600 stuff. But he's problem is and what he can't escape from. He's making claims about this level
1:14:54.320 form multiverse in this sense at least where he said it doesn't imply that all imaginable
1:15:00.080 universes exist. We humans can imagine many things that are mathematically undefined and
1:15:04.720 hence don't correspond to mathematical structures. So he's saying that if they're not mathematically
1:15:08.960 defined here by us, presumably by our mathematicians, then they won't exist in the level four
1:15:14.560 multiverse. But our capacity to imagine stuff is constrained by our brain that obeys these laws
1:15:22.400 of physics here. If the laws of physics elsewhere are different in the level four multiverse,
1:15:26.720 which by definition they will be, then there will be people there whose brains are operating
1:15:31.440 on laws of physics that allow them to compute and hence to imagine structures that we can't imagine.
1:15:37.920 So he's contradicting himself. This itself doesn't make any sense. This is an incoherent notion,
1:15:44.640 which is a problem for the level four multiverse, much less believing in such a multiverse
1:15:49.360 based upon this argument. These are the kind of discussions people have when they've had too
1:15:56.960 many beers or smoked too much weed, I think. It's just, it is metaphysics. It's not constrained
1:16:04.000 by what we know. But if you want to have this sort of discussion, it should. It should at least
1:16:08.880 begin in what we know and what we know at the moment are laws of physics. To the extent that we
1:16:14.400 know them, our best explanations, this is why explanations need to be at the center of our concern
1:16:20.400 about rationally understanding the world and having rational discussions and writing popular science
1:16:25.680 books. Now finally I'm just going to skip way back to earlier in the book, earlier in our
1:16:31.040 mathematical universe, where he mentions proper ones. And as you can guess, as we always say here,
1:16:37.200 whenever I pick up a popular science book, whenever I listen to a podcast, whenever I tune into a
1:16:42.480 YouTube explainer video and car pop up comes up, it comes up in the same way. And it comes up in
1:16:49.760 such a way that it's a misconception. It came up during their conversation. Let's see what Max has
1:16:55.680 to say in the book itself, because it comes to bear on what he thinks about testability.
1:17:02.080 Now he doesn't even think, as I think many others have said before, I think Sean Carroll
1:17:06.560 has said, even though these guys ostensibly endorsed the multiverse, the many worlds interpretation
1:17:13.360 ever ready and quantum theory. They don't, they don't think it can be testable. Well,
1:17:18.160 Tag Mark goes, Max goes even further. He doesn't think that it needs to be testable. He doesn't
1:17:23.760 think, not only does he not think it is testable, he doesn't think it needs to be testable,
1:17:27.440 or should be testable, because he doesn't think multiverse is in general need to be testable.
1:17:32.080 And he says this because he claims multiverses are not theories in the first place. And
1:17:37.280 Papa, he says, he claims when talking about testability was only talking about the testability of
1:17:42.400 theories, not predictions. And the multiverse, he says, is a prediction from a theory. Now that's
1:17:51.840 very cute, but it's completely wrong, but let me just read from page 346 of his book and he says,
1:17:57.680 quote, let's be more specific. The influential Austro-British philosopher, Carl Papa,
1:18:04.080 popularized that they are widely accepted at age, quote, if it's not falsifiable,
1:18:09.360 then it's not scientific end quote. And he goes on to say, physics is all about testing mathematical
1:18:15.360 theories against observation. If a theory can't be tested, even in principle, then it's logically
1:18:21.360 impossible to ever falsify it, which by Papa's definition means that it's unscientific.
1:18:26.960 It follows then that the only thing that can have any hope of being scientific is a theory,
1:18:32.480 which brings us to a very important point. Parallel universes are not a theory, but a prediction
1:18:38.560 of certain theories end quote. Well, look, it's true to say that the claim of anything like
1:18:48.400 X exists is not falsifiable. And Max uses the existence of a banana to point this out. Also,
1:18:55.920 just after this, he goes on to say, quote, parallel universes, if they exist are things,
1:19:02.560 and things can't be scientific. So a parallel universe can't be scientific any more than a banana
1:19:09.200 can end quote. I don't know what that means. Anyone who claims bananas do not exist has a
1:19:19.520 falsifiable claim. So he's completely confused about that. And he's confused because he does
1:19:24.960 not understand the criterion. And he doesn't understand the criterion because he hasn't read
1:19:28.560 Papa is my guess. Or if he has, he's misread him. I mean, Papa wrote whole books, many of them
1:19:34.960 explaining his stuff. It's a whole thing. It's not just, quote, if it's not falsifiable,
1:19:40.720 then it's not scientific end quote. But you know, as I say, this is what passes for
1:19:45.280 preparing epistemology in some places. If someone says, bananas don't exist, pull out a banana
1:19:52.640 and go, there you go. It's a banana. You've falsified their claim. Or there are no bananas in this
1:19:59.040 room, pull out a banana, false. Now, if they, if they still deny it, well, then you're in the
1:20:03.200 presence of an irrational person, that's how falsification works. The thing is one better way of
1:20:08.480 understanding, pop around this point about testability or falsifiability or theories and predictions
1:20:14.960 or whatever. It's just to begin with the assumption, what we're doing is conjecturing,
1:20:19.840 we're guessing at reality. We're interpreting stuff. And on, on that basis, theories and predictions
1:20:27.360 are conjectures. They're all conjectures. It's all conjectural. It can all be tested. Of course,
1:20:32.160 the predictions can be tested. Of course, the predictions can be falsified. Game said,
1:20:37.600 shown to be false, shown to be wrong, refuted. There, there, there are way of interpreting a
1:20:42.640 consequence of a particular theory. David Deutsch actually describes, and in my multiverse
1:20:48.240 series, I spend some time explaining the way in which he would set up an experiment, a possible
1:20:55.600 experiment to distinguish the multisocalled multiverse interpretation, the multiverse theory,
1:21:00.880 as compared to collapse models, right? They're the standard Copenhagen interpretation, this idea that
1:21:05.680 the wave function collapses or some such that there aren't multiple universes. Okay, there is such
1:21:10.880 an explanation that can be done. I don't want to go through it right now, but it will involve an
1:21:15.840 AGI, one day, the future existence of an AGI, able to perform an interference experiment in its own
1:21:22.240 brain. Okay, this, this sort of thing could be done. But also, any test of quantum theory is a test
1:21:28.400 of the multiverse, because they are one and the same thing. And that's what we should be saying
1:21:33.360 if we're going to properly explain these things. So even the defenders of multiverse theory are
1:21:38.560 not doing themselves a favor by claiming in some way, shape or form, these things aren't
1:21:43.840 testable. They are. They are. This is why popularina epistemology is important. This is why having a
1:21:51.760 coherent worldview, as I say, is important. Why having an understanding of how the philosophy gives
1:21:57.520 you a certain kind of epistemology. And the epistemology tells you about the limits of knowledge,
1:22:03.200 what can be known in the way in which it works, certainty and uncertainty. It tells you about
1:22:08.160 mathematics and why mathematics, although it's about necessary truth, it doesn't allow you to access
1:22:13.520 certainty and apt and the absolute truth of anything. It doesn't put hierarchies there in place
1:22:18.960 between science and mathematics. It also doesn't allow you to know the ultimate nature of reality.
1:22:24.560 And it also tells you why that's not even desirable because we want progress and we want optimism
1:22:29.840 and this idea that there is an end point in some way, shape or form to our understanding this
1:22:34.800 ultimate nature of reality is a depressing thought. It also means that you end up with dogmas
1:22:40.080 and doctrines and the idea that the truth is manifest ends up leading to tyranny. So we've got a
1:22:44.560 connection there with morality and politics. It's all encompassing. This is why we like to explain
1:22:50.320 the worldview that's in the beginning of infinity and the fabric of reality and elsewhere.
1:22:54.480 It provides you with this. We're not to say it has all the answers, but it has some sort of
1:22:59.920 coherent framework, which allows you not to make what I regard as clangers of logically
1:23:06.880 inconsistent claims and pseudo-scientific religious metaphysical claims as well.
1:23:14.400 None of this is to say that overall this is what Max is doing. He's not a tag. The
1:23:19.440 overwhelming majority of the book is good, but I think it's just undermined by not having a
1:23:24.560 deeper understanding of philosophy and epistemology. You can't do away with these things. And I
1:23:28.160 think a philosopher should ignore physics, the most important sorts of physics, things like
1:23:33.920 consequences of quantum theory. I think that's just really important to do. Mathematicians
1:23:38.400 shouldn't ignore it as well. None of them should ignore epistemology. Anyone who's versed in epistemology
1:23:43.920 should have some understanding of science is not to say one needs to be an expert in all of these
1:23:48.560 things. It's just helpful. It helps to make progress in any one of these areas if you're an
1:23:54.080 expert in one of them by knowing a little bit of the rest. It helps everyone just to know a little
1:23:59.600 bit. But that's the multiverse, according to Max Tegmark, or the multiverse is according to
1:24:05.120 Max Tegmark. Next time we're going to be talking about minds and I'm going to pick it up where
1:24:10.720 at the end of this conversation, they talk a little bit about AGI. And then the next conversation
1:24:16.160 that they have is entirely devoted to AGI. And they're basically in furious agreement about things
1:24:22.160 and about the dangers to potential dangers of AGI. And just not really understanding that AGI
1:24:27.520 would be a mind like ours, able to universally explain stuff like we can, to be creative
1:24:35.920 like we can. Instead, of course, they make that era of, well, it might just have different goals
1:24:41.920 and it would disregard us, it would have more morality, all this sort of stuff. So we'll leave that
1:24:47.440 until next time. And until then, bye bye.