#115 Phil Halper & Niayesh Afshordi - What Came Before The Big Bang?

19:57Niayesh Afshordi:that's where the elements were formed in particular hydrogen, helium, some lithium, deuterium so these were forged at the Big Bang of course they're forged in the stars as well but primarily at the Big Bang and going before that we have ideas but then we kind of take our ideas and try to push them, extrapolate them to their logical conclusion and that leads us to a point where if you push them, so it's kind of saying that this car is moving that way, okay, is it going to keep moving this way at, I don't know, 60 kilometers an hour? Maybe it's going to go that way for an hour. Maybe it's going to stop in one minute and take a turn.

20:44Niayesh Afshordi:You don't really know because you just know what it's doing now. And that's based on what we're saying. we could kind of extrapolate, but it's like extrapolation could be wrong because it could take a turn. And we're using the rules that we know to do this extrapolation, but the rules that we know kind of stop at some point.

21:01Phil Halper:This is like a backwards extrapolation. Yeah, exactly. Backward extrapolation.

21:04Niayesh Afshordi:Like shrinking the universe down and down. That's right.

21:05Phil Halper:Assuming that that keeps going.

21:07Niayesh Afshordi:Assuming that it keeps going, right. Assuming that it keeps going, it takes us to this point where time stops ticking and densities and pressures and temperatures could blow up, basically go to infinity. So that is what Penrose and Hawking back in the 60s called singularities and they thought it was unavoidable according to those theorems. But those are based on assumptions and we know that assumptions fail and everybody, almost every practicing physicist, thinks at least one of the assumptions that little singularities fail at some point.

21:40Phil Halper:that Hawking sort of cottons onto and says, hold on a second. If you take that singularity business and play it in reverse, you might get something like the big bang and singularity at the beginning of the universe. And this is a sort of reversing of time and an extrapolation or whatever the opposite of an extrapolation is towards the big bang. You just said that that though relies on a few assumptions. What are some of the assumptions that this extrapolation relies on?

22:05Niayesh Afshordi:Excellent. Excellent. So there are basically four assumptions that go in these singularity theorems. And we kind of go over them in our book in a lot of detail. The first one is gravity is always attractive, which we think should be true. I mean, gravity kind of its name is attractive, except that we now have incontrovertible evidence that gravity is not attractive on larger scales. We have this thing called dark energy or a cosmological constant. We've known that for basically almost 25 years now that expansion of universes is speeding up. So right now, this very minute we're talking, on very larger scales, gravity is not attractive, it's repulsive.

22:48Niayesh Afshordi:So, of course, back in the 60s, they didn't know that. So they assumed gravity was attractive. That's assumption number one. Assumption number two is we have three dimensions of space and one dimension of time. That's, of course, I mean, everybody agrees there's three dimensions. of space, X, Y, Z, can go up and down, left and right, front and back. And then there's time, it's ticking. But it doesn't have to be the case. And in fact, as we go in detail, many theories of gravity suggest that there might be extra dimensions, either the extra dimensions of space or time. So that's another possibility.

23:26Niayesh Afshordi:Or maybe you could get rid of one space and add one time or vice versa. Maybe you can, no time and four spaces, et cetera. So assumption number three is that there are no time loops. Basically, time machines don't exist. And I mean, this is, of course, subject of basically indefinite fascinations, infinite fascination, science fictions. Could there be time machines? Could there be not? And I mean, another chapter in our book that we go into is, yeah, there could be very plausible scientific scenarios where there are time machines now. Not all favorite science fiction movies may come true, but there could be some versions of time machines that exist.

24:09Niayesh Afshordi:And assumption number four is at some level at the heart of basically any theorem is that you need to assume some mathematics, some mathematics, basically. And the mathematics is mathematics of Einstein's theory of general relativity. But that one, that also we know has to break at some point because quantum mechanics is this other theory, as I mentioned before, that we have, which is very successful. The reason you and I can talk, your viewers can actually watch us is because engineers have used the rules of quantum mechanics to engineer basic technology for us to be able to communicate. So rules of quantum mechanics are very, very successful, happen to be inconsistent with mathematics of general relativity.

24:49Niayesh Afshordi:So that needs to be revised as well. So these four assumptions, at least one of them, maybe all of them fail at some point. So this idea of kind of extrapolating back in time, that definitely fails. And that opens up kind of the door for all imaginative ideas that we still have to put within straight jackets. So this, Feynman has this famous quote that science is imagination in straight jackets. So we are free to imagine things because there is no definite answer at that point. But still, what comes out of whatever we imagine should match our detailed observations of the Big Bang. Cosmic microwave background, distribution of galaxies, the geometry of the Big Bang, the sound waves that we measure coming out of the Big Bang.

25:39Niayesh Afshordi:So these are all the things that whatever imaginative, creative thing you come up with, has to explain.

25:46Phil Halper:And this is no joke, ladies and gentlemen. I mean, all of this talk about time loops and the Big Bang not being the beginning of everything. One thing that I love about this book is, I don't know what you consider the genre of this book to be, whether you consider it to be, it's kind of a history in part. It's like an overview, almost like a survey. But what this book does, Battle of the Big Bang, should become clear to people now that the battle is for the model of what banged, you know? And the great thing about the book is that you sort of remain agnostic. I mean, not personally agnostic, but the book is just exploring these ideas.

26:20Phil Halper:And so if you're interested in this stuff, the book just sort of just goes over these ideas and says, look, here's an idea, you know, take it or leave it. That's why I love this so much, because it's one of those books that doesn't profess to have an answer. So you just have to sort of go away and give it some thought. And one of the big questions is that throughout all of these different models, and you talk about some 25 or so different models of what the Big Bang actually was and how it worked, is you've actually got a cheat sheet at the end, a big table of like, does it involve inflation? And one of the columns in this table is, does this model say the universe has a beginning?

26:57Phil Halper:And the majority of them say no. That's right. So hold on, if the Big Bang is not the beginning of the universe, and if you've got this whole table, which says here are dozens of models of the Big Bang that don't say that the Big Bang is the beginning of the universe, then what is the Big Bang and what on earth came before it? I thought they're talking about before the Big Bang didn't make any sense. It's like asking what's north of the North Bolt. So what are we talking about?

27:22Niayesh Afshordi:Yeah, well, we're talking about not the beginning of the universe, but rather the end of our current theories. And what we need are better theories. So it might be that Einstein's theory of general relativity tells us the Big Bang was the beginning, But almost nobody in physics thinks that Einstein's theory of general relativity is applicable at the Big Bang. As in the IS said, we need a theory of quantum gravity.

27:42Phil Halper:Is that because the Big Bang is so small? Or why is it that general relativity breaks down at the Big Bang?

27:49Niayesh Afshordi:I wouldn't necessarily say the universe is small at the Big Bang. It could have been infinite at the Big Bang. It could be infinite now. We don't know how big the universe is. Rather, it was denser. That's the point. It was much denser and hotter in the past. But not smaller. So what's smaller is, if you like, what we would see. So our horizon, that's shrinking. So the observable universe, you might say, is getting smaller.

28:14Phil Halper:But what does it mean to say that it might not have actually been smaller? I mean, again, like it's difficult to imagine, right? But when I think of even just the big bang of the hot, dense state, you know, forget the singularity, I'm imagining in my head again, here go my hands, you know, something sort of shrinking. Is that like the wrong way to be thinking about it? So think of like this room.

28:35Niayesh Afshordi:That's what you can see at the moment. I can't see what's outside this room. So similarly, we can see out quite far, but nobody thinks the distances that we can see, billions of light years, is the whole universe. So that bit that we can see, you can think of that as shrinking. So the observable universe was smaller at some point. So I have another analogy for you actually, which is, I think it's even mathematically reasonable actually. So we know about black holes. You heard about black holes. Black holes have these horizons that if you fall into them, you cannot get out. Event horizon of a black hole.

29:09Phil Halper:The point at which not even light can escape.

29:10Niayesh Afshordi:Not even light can escape. So if you're outside, in principle, you can shine a light. But if you fall inside of it, even if it shines a flashlight, it cannot get out. Universe is actually, even today, The universe is like a black hole inside out. So we have a horizon, but instead of being outside the horizon, we're inside the horizon. So we are surrounded by it. And there's a point, basically, if you go beyond that, you cannot return. So we cannot see people beyond that horizon. And it's kind of like they are falling to the black hole, except that we are in the center and the horizon surrounds us everywhere.

29:52Niayesh Afshordi:Wow, okay. And is that to do with the expansion of the universe? It has to do with the expansion of the universe. The expansion of the universe is actually stretching everyone, pulling everyone apart. And at some point, there is a point that we are being pulled apart in some sense faster than the speed of light, which you think it should be impossible. But this is the thing. I cannot move faster than the speed of light relative to you, but the universe somehow can move faster in the speed of light, it's something that's in fact within the mathematics of relativity itself. You're not really violating anything because there's no particle that's moving faster in the speed of light.

30:33Niayesh Afshordi:It's the space itself that's moving faster. But then basically what it's doing is that, yeah, so those things are just kind of moving so fast that we cannot see them and they're outside. You can think of it as expansion of a space or you could think of it as just like the way you think of a black hole but inside out. and the distance to this horizon just gets smaller and smaller as they get closer and closer to the Big Bang. So the space could be infinitely big, we don't know, but I mean it's consistent with observations that space is infinitely big. But the amount of space that we can see up to the horizon, basically, the cosmological horizon, becomes as smaller and as small as you get to the Big Bang.

31:15Phil Halper:Yeah, as if we had a huge sort of fabric, and I just took this little bit of the fabric and stretched out that bit of fabric. That's right. And that like within that bit of stretched fabric, you could see everything around you like flying apart and think that all must have come together, but it could just be one tiny little ripple in a massive, massive fabric. That's right. I love this black hole inside out thing. That's really hard to think about. And I think for people to understand if the universe is expanding, it means like if something Something is expanding away from you. It means that the further something is away from you, the faster it's moving away relative to you, right?

31:49Phil Halper:You can sort of imagine, stood in the middle of a fabric or the famous example of a cake, like a raisin cake or a chocolate chip cake, expanding.

32:00Phil Halper:And like, if you were in the middle of that cake, the raisins or the chocolate chips just next to you would be moving away slowly. And the ones at the very edges would be moving faster. As the universe gets bigger and bigger at the very edges, those chocolate chips are moving away so fast that if they're moving faster than the speed of light, or rather the space is moving, so that it has that effect, if that chocolate chip is moving away from you faster than the speed of light, then when light comes off that chocolate chip, it can't reach you. Because the whole thing is moving away faster than the speed of light.

32:30Phil Halper:It's kind of like a car driving away faster than the speed of sound. If you play a sound, that sound's never going to reach you because it's zooming off with the car and so you just reach the limit of our observation yes right like anything that's beyond that point even if it's emitting the brightest light on earth it just doesn't have the time to reach us because it's all expanding away from us and so so i think i should stop you there i mean as a as a student

32:54Niayesh Afshordi:at relativity i say you shouldn't um compare sound and lights and and that because in fact Like, sound always travels with its medium, right? Oh, sure. So, yeah, yeah. So, no matter how fast the car moves, the sound that comes to us is the speed of sound with respect to air.

33:18Phil Halper:Whereas light just...

33:19Niayesh Afshordi:Light is independent of frame, right?

33:22Phil Halper:Yeah.

33:23Niayesh Afshordi:So, I think it would be true that if there's a sound and you're moving, like you have a supersonic plane, then you may not hear, basically, because it's moving very fast in the speed of sound. But if the supersonic plate make a sound, we're going to hear it. Because the sound is propagating with respect to... I think it's helpful to visualize.

33:41Phil Halper:I mean, I guess if people are struggling to imagine this, imagine like a car moving at 10 kilometers per hour to the right. And imagine that it emits, relative to the car, it emits like a particle that travels at 5 kilometers per hour in the opposite direction. That's right. Like, because the car is moving 10 kilometers that way, and it's moving relative to the car, that particle will actually be moving away from you, I guess. That's right. And so it would never actually reach you, even though it's been emitted from the car towards you. If the overall movement is away, that particle goes away.

34:14Phil Halper:And so light would function in a similar way, that the light would, relative to you, be traveling away and would never reach you. And so we just reached the limits of our observation. And so, okay, maybe then the Big Bang is like a localized ripple in a larger fabric, but like how can we begin exploring that question if we're talking about you know anything outside of the big bang being like by definition beyond our observational capacities how can we even begin writing a book like the battle of the big bang surely the only answer is we have absolutely no idea and can never have any idea okay good um you were asking what is this book actually i just

34:54Niayesh Afshordi:had an idea you heard about the schoeninger's cat there's like a dead cat and alive cat it could be the same. So this book is like a Schrodinger's book in the sense that it's a fiction book and a nonfiction book at the same time. So we're trying to get to what's fiction, what myths about the Big Bang. And there's a lot of myths about the Big Bang. There are some that we talked about, but there's also myths that kind of cosmologists believe in and they think it's supported by evidence or they think it's proven. For example, there is a leading theory of the Big Bang, known as inflation, which suggests that the universe was expanding very, very fast, a very, very tiny fraction of a second, was doubling basically every tiny fraction of a second, expanded by 30 orders of magnitude or so.

35:44Phil Halper:This is right near the beginning.

35:45Niayesh Afshordi:Right near the beginning. And this is, so this is an idea now.

35:50Phil Halper:As you explain that, what's the difference between, you know, the Big Bang theory as a whole is a big expansion at the beginning of the universe. So what's inflation as a distinct thing? than just the Big Bang expansion.

36:00Niayesh Afshordi:Very good. So the difference is whether gravity is attractive or repulsive, right? So the expansion is expansion. But you remember I told you that right now the expansion is actually speeding up. It is expanding, but then it's actually getting faster and faster. So the gravity is even speeding up. So inflation suggests that something like that happened near the Big Bang, or in fact, just before the Big Bang, before the hot Big Bang. Depending on the terminology, right? Depending on the terminology, exactly.

36:31Phil Halper:Just to be clear, when you say before the Big Bang, if by the Big Bang we just mean the hot, dense state, then there could easily be something before. When you say before the Big Bang, people need to get rid of this idea that you're talking about before the singularity or before the point of creation. The Big Bang can just be used to describe this hot, dense state. That's right. Inflation is the idea that there is this exponential speeding up kind of growth rather than just a sort of linear growth.

36:55Niayesh Afshordi:Yeah, exactly. So this repulsive gravity, the idea is that there was repulsive gravity much, much stronger than it is today back then, before there was this hot, dense state of the Big Bang. And that kind of stretched the universe by 30 years of magnitude. Basically, there are 100 doublings or so, basically. The universe doubled in size in a tiny, tiny fraction of a second, many, many times. And because the reason it could do it is gravity was repulsive and very, very repulsive. And what it does is that it kind of takes a tiny speck where you could have tiny quantum fluctuations in it and it stretches it across the universe.

37:30Niayesh Afshordi:So you get this very big universe, which is very uniform, the way we see it, with tiny fluctuations, which turn out to basically become these sound waves that we see that basically form. We see the ripples in the cosmic microwave background and then eventually they form galaxies and stars and everything. So inflation is a leading theory. And many scientists, many cosmologists think it's proven. And we argue it's wrong. In fact, there are others, many other leading scientists, like many we name, like Roger Pendles, who actually one of the originators of singularity theorems and won a Nobel Prize for them a few years ago.

38:13Niayesh Afshordi:He thinks that inflation is not really a reasonable theory. And we go over all other ideas. But here's the thing. So there are a lot of myths, and we try to go over them, and we'll discuss what evidence there is. But we also say that it's not really mythology what we're doing, because there are very precise measurements, and there are many of them. There are dozens of them that we talk about. Again, this cosmic mark of a background, we talked about his discovery, but in fact, what's the most amazing thing about it? And this kind of takes us back to Fred Hoyle, because Fred Hoyle named Big Bang, but he was a critic, I mean, pejoratively or not, he was a critic of Big Bang.

39:00Niayesh Afshordi:But I think inadvertently, he maybe gave a very good name to this theory we talked about. Because bang, when you think about bang, it's something loud. And our best evidence for what happened at the Big Bang is the sound waves. We cannot quite hear it with our ears, but there are ripples, variations in the cosmic Markov background that were just the sound waves, the primordial sound waves that must have been created at the Big Bang or before the Big Bang by whatever that happened there. and these properties of the sound waves are measured very precisely now how big they are, how they change on wavelength or dependent wavelength now they are stretched on millions or billions of light years so they are much bigger than much longer sound wavelength than the sound waves we used to communicate right now but they are there and they are measured very precisely and any speculative weird time travel idea you come up with has to explain them And that's kind of, that's why.

40:01Niayesh Afshordi:These are sound waves that we measure now? These are sound waves that, well, we measure now because we exist now, but it's kind of, we measure them indirectly because, so what happened was they were propagating across the universe, but at some point, the universe.

40:17Phil Halper:This episode is brought to you by Indeed. When your computer breaks, you don't wait for it to magically start working again. You fix the problem. So why wait to hire the people your company desperately needs? Use Indeed's sponsored jobs to hire top talent fast. And even better, you only pay for results. There's no need to wait. Speed up your hiring with a$75 sponsored job credit at indeed.com slash podcast. Terms and conditions apply. It becomes basically low density. So sound waves kind of freeze. Yeah, because people want to know like how can sound waves travel across the universe if the universe is this sort of vacuum.

40:55Phil Halper:You need air for sound to travel.

40:56Niayesh Afshordi:Good, good, good. Yes, yes. So, I mean, the universe is not empty. There is matter in the universe, right? And it was dense at the early time. So we had this primordial plasma that's very high density. So sound waves could propagate in it. Primordial plasma.

41:09Phil Halper:And this is like a state of matter, similar to the surface of the sun. Exactly. This kind of state where when everything's dense enough, it's the kind of thing that sound could propagate through, like throughout the whole universe, because the whole universe is like plasma.

41:22Niayesh Afshordi:I told you, universe is like a black hole inside out. I mean, the Big Bang is kind of like a star inside out. I mean, I guess an empty universe is like a black hole inside out. But if you have matter and Big Bang, so Big Bang is like a star inside out, like a sun inside out. So we can see the surface, right? And in fact, literally, it's the same analogy, right? So we can see the surface of the sun. We cannot see inside the sun, right? And the same as we began. We can see this thing called the last scattering surface, which is kind of the surface of the big bang is where light can the density is low enough so light can propagate to us but then beyond that light cannot propagate directly but sound waves can and in fact that's exactly the same way we can probe what's inside the sun of course we have our mathematical models but there are also sun quakes it's called like helioseismology is a sign so so because sun is kind of very active you could if there are solar flares in fact feel is very good and imaging all sorts of sun-related things and auroras and then the pictures of the various

42:22Phil Halper:phil's own images appear in the middle of the book and i i must put a link to your like was it your flicker account or whatever phil is also a phenomenally talented like space photographer it's like i i was blown away the first time i saw it so i'll i'll try to remember to put that in the description as well so yeah but yeah the the sun the sun yes the sun is a very active place

42:42Niayesh Afshordi:and there are all these various activities that happen. But in particular, basically, there are waves that propagate in the sun. And by mapping these waves on the surface of the sun, so these are sun waves and also there are gravity waves, there are different types of waves. By mapping these sun waves, you could actually map the structure inside the sun all the way down to the core of the sun. Which is also kind of how we know what's inside the Earth, because there are also earthquakes, and by mapping those…

43:07Phil Halper:So we're looking at the effects on the surface, the sound waves, the gravity waves, and from that we're seeing what's in the center. That's right. And the Big Bang is like a star in reverse. Exactly.

43:17Niayesh Afshordi:And that's what we do with the Big Bang. We see the surface of the Big Bang. It's obviously inside instead of outside, so it's kind of inside out. But still, we can see the ripples on the surface. Yeah, we're looking at the surface from the inside. Exactly.

43:28Phil Halper:That's interesting.

43:29Niayesh Afshordi:Yeah. But it's the same kind of process. It's the same idea. And those sound waves can go much deeper inside. And then there's something even more exciting. In fact, I mean, for the sun, there was something like, that was a big breakthrough. There were neutrinos. This is another type of particles. It's even, it's kind of complementary to the sun. So neutrinos are these weakly coupled particles that are made at the fusion in the center of the sun. And we eventually detected them. We've been detecting them for a few decades, but they weren't quite matching until we detected all different types of neutrinos.

44:02Niayesh Afshordi:So the key is that you want something that kind of can freely propagate in a space. For the Big Bang, there are neutrinos. It's just very hard to see, so we haven't quite cracked that nut yet. But there's also something possible, which is called gravitational waves. So these are ripples or fluctuations, basically waves in geometry. So even if there's nothing, you could have geometry of a space according to on-censory relativity, which could ripple and wave. And those could have been emitted from the Big and there are many theories, some of the theories of the Big Bang predict that these waves are there as well.

44:39Niayesh Afshordi:And there are many experiments that are looking and we have been actively looking for those. So these are all the things that can come out of, we can detect directly or indirectly from the very, very early moments, well beyond what we've seen today. And they could kind of probe these various speculative ideas and rule some of them out. And this is why it's not all fiction, there is some non-fiction as well.

45:01Phil Halper:Phil, why is inflation an important idea? Why do so many scientists believe in it? And why are you suspicious of it? And I mean, particularly the way that we've just described inflation is the inflating of the early universe. And a lot of people will listen to that and go like, okay, I thought we knew that already, the big bang, the universe expands. You might say, no, inflation says that it's speeding up. It's like, well, I thought we kind of knew that already. Anyway, you know, everyone knows the universe is expanding and kind of who cares? Okay, it's faster. What's the importance of this inflation idea?

45:35Niayesh Afshordi:Well, I think there's two reasons why it's so profound, if it's true. And we can go over reasons why it might be true and reasons why it might not be true. But let's go to the implications. One, as we said, inflation is a pre-Big Bang model. It happens before the Big Bang. So if we can confirm inflation is true, then we can tell what happened before the Big Bang.

45:55Phil Halper:So what does that mean? So what is it that's inflating?

45:58Niayesh Afshordi:Okay, so it's the space that's inflating.

46:00Phil Halper:And so this is before the hot dense state. Yes, before the hot dense state. So what are we talking about here? Help us to visualize this.

46:06Niayesh Afshordi:Just, well, imagine an empty space, but it's filled with a field maybe that will push the universe to accelerate in its expansion. So - But this is not hot and dense. No, no. It would be as cold as it could be. And then when inflation ends, all the energy in that inflating space actually is converted into matter and radiation then you have the big bang then it's hot so so the big bang is what happens after inflation whereas a lot of textbooks will tell you it's big bang then inflation but but even i interviewed alan the inventor of inflation and he he calls it a prequel to the big bang so so inflation big like

46:50Phil Halper:sort of exponential increase in the size of space, am I allowed to say that? You can, but remember the caveats that we said before, yeah. And then inflation for some reason stops.

47:01Niayesh Afshordi:Yeah, because it's supposed to be unstable, so it decays. This is the next most important implication.

47:08Phil Halper:Okay, but then the energy of that expanding space turns into matter and radiation, and that matter and radiation is the bank. Is the bank, yes, absolutely.

47:18Niayesh Afshordi:But here's the other super profound implication of inflation. While this inflating space is decaying, it's also expanding exponentially. So you could imagine it like a radioactive particle decaying, it decays with a half-life. So imagine one bit decays, that's our Big Bang, that's our universe. But think about the bit that's not decayed yet. What is it doing? Well, it's exponentially expanding. so what happens is the volume of inflating space cannot go down as long as the exponential expansion is faster than the the decay then the volume of inflating space will just go on increasing forever so then at the next half-life you'll get another big bang then it expands again or the bit that you hasn't decayed it keeps expanding so you get another big bang so analogy I use is Sunday afternoon when I go to my mom's house and she makes this fantastic chocolate cake.

48:16Niayesh Afshordi:It's really yummy. And she puts the cake down and we all have a slice and half the cake is gone. Then a little bit later, we go back for seconds. The whole cake's gone. You can't have your cake and eat it. But imagine if the cake was doubling in size very, very rapidly, then we went back for more cake and the cake has got bigger. So now we just have the same slices of cake that had before and we could just keep going forever.

48:39Phil Halper:So in this analogy, what is the cake? What is the thing that's getting bigger and bigger?

48:43Niayesh Afshordi:It's the space, the inflating space.

48:45Phil Halper:The inflating space and our universe is not that inflating space.

48:49Niayesh Afshordi:No, it's what came when that inflating space decayed into matter and radiation.

48:54Phil Halper:Help me picture this, right? So we've got inflating space, this is inflation, you've got space sort of getting bigger and then inflation stops.

49:00Niayesh Afshordi:In our patch.

49:01Phil Halper:So you've got this sort of big inflating space and it's just a little patch of that inflating space that stops inflating, which causes this vroom, like energy, matter, all this kind of stuff. But the whole thing is still expanding. And so that little miniature part is expanding locally as well. But outside of that - It's expanding even faster. And there might be other patches that keep stopping and slowing because inflation is unstable. And so there are little patches where it stops and that's vroom, vroom, vroom, vroom, vroom, big bang, big bang, big bang, maybe little bang, medium sized bang.

49:37Niayesh Afshordi:That's what most inflationary cosmologists suggest. Okay.

49:39Phil Halper:So does that mean that this inflationary idea points to a multiverse? Yes. Is that what we're talking about?

49:45Niayesh Afshordi:That is where the idea of a multiverse comes from. I mean, there's another view from quantum mechanics, but that's generally considered quite separate. Yeah, sure. But this idea of the multiverse is coming from inflationary cosmology and that is quite mainstream.

49:58Phil Halper:I'm often told that the only reason people believe in the multiverse is as a way to get out of the fine-tuning argument for the existence of God. In other words, the multiverse, we can't say it's false, it's ridiculous, and we're not going to say it's ridiculous, but there's no evidence for the multiverse. It's essentially like a philosophical tool that people use in religious arguments, but not the case. No, definitely not the case.

50:19Niayesh Afshordi:I mean, it was a discovery. Someone didn't look at the fine-tuning argument and say, well, let's have a multiverse. No, what happened was they were looking at inflationary cosmology. And then it was actually Nia Esh's colleague at Princeton, who was one of the first to realize that inflation would make a multiverse. This is Richard Gott. He's also the master of time travel. He's an expert on time travel and lots and lots of things. So he was one of the first to say, inflation would just make a multiverse. But at first it was thought, well, these are sort of curious solutions to inflation. They didn't really take it very seriously.

50:55Niayesh Afshordi:Then another scientist came along called Alex Velenkin and Andre Lindey as well. And they showed that this was a generic property of inflation. So Alan Guth, there are actually lots of different inflationary models. But what Guth says, he's the creator of inflation, is that almost all models of inflation are eternal. So they will make a multiverse. So independent of any argument about fine tuning, we have an argument for a multiverse coming from inflation. So if you take inflation seriously, then it looks like it generates a multiverse. Now, there are one or two cosmologists, Slava Mukhernov's one, that don't agree with this.

51:30Niayesh Afshordi:But I think I've interviewed a lot of the people that worked on inflation. I would say that's a consensus view, that if you have inflation, then you have a multiverse. And then we can ask, is there evidence for a multiverse? And that depends on your view on whether there's evidence for inflation, because a lot of cosmologists say there is evidence for inflation. In fact, they think it's very strong evidence. Some people say it's been proven. and what we argue in the book is well there's good arguments back and forth about this you you can say you know inflation made lots of predictions but then you can challenge that and say well maybe um that's that's a dubious statement so i mean uh i think niash is more in the anti-inflation camp whereas i change my mind like every other day about this sometimes i think the inflation is really uh strongly supported and others times i'm with it i think Phil has to be very diplomatic because he interviews all people.

52:21Niayesh Afshordi:So I can be more strongly ordered. But in the book, we try to find a common voice so that no one gets offended.

52:28Phil Halper:To be clear, Alan Guth is not the creator of inflation. No, he is. He's the guy that came up with the idea, but he's not the man who created the inflationary universe.

52:39Niayesh Afshordi:But we do talk about whether it's possible to make a universe in a lab. That's the other thing, right? And Alan Guth is one of the scientists who suggested that it might actually be possible.

52:48Phil Halper:Okay, look, I want to talk about that. But also, I want to take a moment because you guys have been writing about this for, it must have been years now, on this particular book and before that a long time. The series you're referring to before the Big Bang, which is on YouTube, it's on your channel, Phil, which I'll also make sure is in the description if people want sort of a documentary version, I suppose, of this book. um and you're so wrapped up in it i think that when you're talking about these models and inflation and stuff it's exciting but we've got to take a step back and realize that people are listening to this with no idea what we're talking about right so they're like okay so let me get this straight there's this idea of like the big bang okay the terminology we should use is that the big bang is whatever the hot dense state is at the beginning of like our observable universe there may have been some stuff existing before that this sort of like empty space that is expanding and expanding in such a way that there are little local patches of you know creations of like mini universes everywhere there are going to be a few questions that come to mind firstly so what is this like thing that's expanding what is this empty space it can't be empty if stuff is like coming out of out of nothing you know there's got to be something there that's expanding Secondly, we talked about inflation stopping because it's unstable.

54:04Phil Halper:I'm not really sure what that means. But the thing that really gets me is like, okay, there's empty space and it's expanding, and then it stops, and then, vroom, matter and energy, just out of nothing, out of nowhere. You know what I mean? Can we take a step back? Now that people understand what we're talking about, this big space that expands exponentially, potentially, and little pockets of instability, people are going to be like, but what is this? What are we talking about? How does this matter and radiation spring up? Where is this coming from? You know what I mean?

54:35Niayesh Afshordi:So imagine a pool table but imagine there's a hole in the middle somewhere and so imagine there's no friction I should not imagine too much so imagine there's no friction so imagine you can hit the pool ball and it just keeps bumping left and right and is all over the place right so so that's kind of uh like a quantum sea or if you want so so that's the pool table is inflation like universe somewhere in there every now and then it may come across this tiny hole and fall into it and then that's where it ends right but it it's it's the thing is that this this ball does different different i mean the state of a space doing different things in different places.

55:26Niayesh Afshordi:They don't talk to each other. It's an infinite universe, right? So some places in the universe, this ball may fall into the hole and that's where you get a big bang. And then you can kind of see when the ball falls, then it's kind of, you make, it heats up, right? So that's, I mean, that again, it's an analogy. You shouldn't take it too seriously. But what you're doing is that there is energy in empty space, right? And this is the important thing is repulsive gravity is not such a strange thing. In fact, any kind of energy that you associate with empty space is going to give you repulsive gravity.

56:03Niayesh Afshordi:And the simplest model for dark energy we have now is energy of empty space, the so-called vacuum energy. And it could have been the same with the big, with the inflation. It's just that a much heavier empty space, the vacuum energy during inflation would have been much higher because there were much faster expansion, much faster repulsion, a much stronger repulsion. But still, what happens is that, so universe is basically, is inflating. This is your pool table. Anywhere in there, there is some huge vacuum energy. And universe, I mean, you think it's vacuum, nothing is happening, but vacuum in quantum mechanics is actually a very vibrant place.

56:41Niayesh Afshordi:There's a lot of fluctuations that are happening. Things are moving around. So, I mean, the ball in the pool table moving around, this is like a classical thing. But really, I mean, all the fields in the space are vibrating very violently in quantum mechanics.

56:58Phil Halper:So this empty space is this sort of ocean of quantum fluctuations.

57:02Niayesh Afshordi:That's right, exactly. And that's everywhere, right? But the thing is, the idea of instability is that it could be, and it doesn't have to be, but I mean, for Big Bang to happen, there needs to be an instability. There needs to be a hole somewhere where inflation needs to end. So in your big pool table, if your ball, which is kind of the state of your space or your field, if you want, it's called fields, I guess, instead of billiard balls, we call them fields in physics. So if your fields come across this hole, they may fall into it. And that's where kind of they heat up and then you create matter and radiation and stuff.

57:40Niayesh Afshordi:But this is something that happens kind of randomly, stochastically, and it doesn't have to happen everywhere because it's just a random fluctuation. In some places it happened, those places we make a pocket universe, and we happen to live in one of those pocket universes. Because we cannot live anywhere else. Like in this vast sea on the billiard table, there's nothing there. There's just vacuum, right? So we need matter and radiation, and we need fluctuations to actually grow. We cannot live in vacuum.

58:08Phil Halper:Okay, so this empty space that's expanding and inflation is not truly empty in the sense that it contains sort of quantum fluctuations. That's right. And some of these fluctuations sort of pop matter and energy into inter-distance. That's right, yeah. Okay. Inflation then, I'm imagining before our Big Bang, we've got this space that's growing. Does that mean that if I play that in reverse, that empty space of quantum fluctuations and stuff would shrink? Meaning that eventually we still have to get back to this singular point from which everything expands. It's just now instead of talking about our universe, we're talking about this empty space of quantum fluctuations, which is not actually nothing.

58:46Right.

58:46Niayesh Afshordi:Right, Phil? Well, okay, so there's a big question. So inflation is often called eternal inflation because once it starts, it can never stop. It will make universe after universe after universe. Now there's a question, okay, it's future eternal, but is it past eternal? Can it just go back forever? Remember Niaesh said that one of the assumptions of the singularity theorem that proved the beginning of time was that gravity is always attractive. Now we're talking about repulsive gravity. So we violate the Penrose Hawking theorem that proved the Big Bang was the beginning. So maybe we don't need a beginning anymore.

59:25Niayesh Afshordi:Maybe inflation is past eternal as well.

59:27Phil Halper:But surely if we're thinking about going backwards in time, if something is shrinking... But remember, the whole universe could be infinitely big, right?

59:35Niayesh Afshordi:So when we said shrinking, it was only a particular patch that we're concerned of, the equivalent of us in this room or what we can see.

59:42Phil Halper:So inflation is not like a thing that happened and it's now over and done with. The idea is that inflation is like the status quo. That is just what's going on.

59:53Niayesh Afshordi:The majority in this scenario, the majority of the universe is inflating.

59:56Phil Halper:And that never ends. It's just inflating, which is exponential growth. Yes. And that just keeps going forever and maybe it's past eternal. So that's the debate.

1:00:03Niayesh Afshordi:Is it past eternal?

1:00:04Phil Halper:And little universes sort of pop up here and there. Yeah.

1:00:05Niayesh Afshordi:So people often quote a theorem by Bordeaux, Guth, and Vilenkin. Yeah. And that says that inflation cannot be past eternal. However, other scientists have said actually it can be past eternal. They made mistakes in their mathematics or they made some assumptions. And so maybe it can be past eternal. And obviously we can't tell. There are claims that inflation is verified empirically, and we can debate those claims. Is that true? Is that false? But nobody would claim that we could empirically check whether inflation is eternal into the past or not. That's something only we can investigate through theory.

1:00:41Niayesh Afshordi:And Unfortunately, theorists don't agree about this. So we don't know whether inflation would be past eternal or not.

1:00:47Phil Halper:We're not looking at this hot, dense, big bang, matter energy. We're talking about the beginning of inflation, which as far as I understand, is something which applies to this quantum soup, for lack of a better word, and that would therefore have some kind of beginning. I don't know, is there time in this inflating quantum soup? because I thought that time was like a dimension of space and if space is part of our universe like does that apply outside of it you know like I'm struggling to like visualize it I'm visualizing almost this like fabric expanding it's a bunch of like lines going through space that's growing and growing and growing And it's full of quantum fluctuations.

1:01:28Phil Halper:Does time pass in this inflationary universe, for example? Okay.

1:01:34Niayesh Afshordi:No, no. It sounds that there is an, I mean, these all sound very mind boggling and science fictiony, but in fact, the physics of inflation is like the most conservative kind of physics you can find. So there is time, there is space, there is energy, everything kind of works in the way that Einstein thought it would a hundred years ago or so. Now, I mean, there are quantum fluctuations as well. I mean, quantum fluctuations, I guess, famously, Einstein said that God doesn't play dice. So he had like a mixed relationship, a conflicting relationship with quantum mechanics.

1:02:06Phil Halper:Yeah, that's a famous quote, Einstein saying God doesn't play dice with the universe. I only found out from your book that Niels Bohr responds by saying, Einstein, stop telling God what to do. Right.

1:02:16Niayesh Afshordi:That's true. Yep, yep, indeed. But these are all like 100-year-old ideas. You're just kind of pushing them to the extremes. And I think that's what gives you this idea of multiverse and inflation. So in fact, these are not the most radical things we discuss. This is the most conservative thing we discuss in the book. It's as mind-moggling as it sounds. because basically it's just saying that, yes, I mean, early times, there was this huge vacuum energy. But, I mean, vacuum energy, again, it's something, a standard quantum theory can give you a vacuum energy. It may not give you the right amount of vacuum energy, but it can give you a vacuum energy.

1:02:57Niayesh Afshordi:It just said you had a big vacuum energy early on, and there are fluctuations around it. There's regular time, regular space. And, yeah, so I think everything works. in the most conservative way possible in eternal inflation. It's just a very weird, different place because we are pushing the laws that we know to the extremes that are very unfamiliar to us or unfamiliar to the universe as we know it today, right? But the more mind-boggling things are, for example, if the entire space, well, time didn't exist at some point, and that's a separate scenario. For example, Hartan and Hawking proposed that maybe inflation was not eternal.

1:03:40Niayesh Afshordi:It actually started, maybe time started at some point. And it's actually, I mean, very reasonable point is that because we know we want a theory of quantum gravity, we know quantum mechanics and gravity, at some point they're going to come to it. So what does it mean and how does it look like? And one way it may look like is that maybe at some point, time, which is essential part of theory of relativity, because relativity is a theory of space and time, maybe time doesn't exist at some point. At this time, in the classical sense that we know. So I think the analogy that Phil uses is like the wetness of water, right?

1:04:19Niayesh Afshordi:So we all are familiar with wetness of water. But if time is like wetness of water, that fundamentally doesn't mean anything, because the water, if you could look at it with a very powerful Microsoft, is just made out of molecules, right? There is no fundamental concept of wetness. It's just an emergent concept. So what if time itself is an emergent concept? And right now there is a reasonable definition of time. But if you go back at some point, that just ceases to exist.

1:04:45Phil Halper:What does it mean to say that there is like time begins at some point? Like it seems to me that in order to say at some point, you need to sort of place it on a timeline. Right. If you're talking about the beginning of time itself,

1:04:58Niayesh Afshordi:Right, right.

1:04:59Phil Halper:Like what could that even mean? I mean, trying to place the beginning of time at a point in time. Right, right. It's like trying to place the origin of all matter in a particular location or something. You know what I mean? Like what could it mean to say the beginning of time?

1:05:12Niayesh Afshordi:Well, I mean, you could try to be precise about it. I mean, you could say, okay, so when you're asleep and awake, right? So where is the exact point where you go from being asleep to being awake? And I think it's, I mean, we could try to define it more precisely if we have a precise theory. But it kind of tells you that, I mean, if you think about it, we have experiences. I mean, physics is the same. I mean, everyday experiences, we don't necessarily quantify it when we are asleep or we are awake. I mean, I suppose physicians can quantify, take our pulse and say, okay, so this is asleep. This exact point is where someone falls asleep.

1:05:54Niayesh Afshordi:But that's not really the point. The point is that we have an approximate description of something. And that approximate description might be good when now you and I are talking. But at some point, that approximate description, the way I understand the word, gets kind of more and more fuzzy.

1:06:11Phil Halper:My issue isn't trying to figure out like when time began. My issue is just with the concept as a whole, right? Because if I imagine that if we go back and back and back, there's a point at which time stops, time doesn't exist anymore. I'm sort of imagining being at that point where there's no time. If there's like no time, like that means sort of we're existing timelessly. how can we then say okay there's no time no time is passing and then at some point time starts you know surely if it's timeless and the universe doesn't exist yet and it's timeless then the universe has to timelessly not exist how do you get this beginning of time at a point in time

1:06:54Niayesh Afshordi:you get what i'm saying well one definition of time i don't know if everyone i don't know if agrees with this but one definition of time that one physicist said to me was that it's a correlation between events. So if you don't have correlations between events, there's no time. But that doesn't mean there's nothing happening. So things could be happening even if there's no time, because there's no correlation between events. You can't make a clock.

1:07:15Phil Halper:This will depend on your theory of time, right? So people are probably broadly familiar with the A and the B theory of time. I spoke to Emily Kreshi-Hurst on the show the other day, who helped to introduce me to the concept of the C theory of time, which if the A theory of time is that time really passes and the past doesn't exist anymore and the future doesn't exist yet and the b theory of time is the block universe where the past and the future all exist and you know we're sort of somehow privileging a particular moment but the past exists and the future does too the c theory of time is that like there is just the relation of events you know and there's no direction of time and she she sort of said like you know to have time you just need to know that you have like World War II and you have like this podcast and they are like related to each other.

1:08:05Phil Halper:There's no sense in which there's an objective direction. There are just relation of events. The only thing that matters is that they're in the right order. So it doesn't matter that like you don't need to say that one comes after the other, but you can't put the death of Queen Elizabeth like outside of that. That has to go in between them, but time sort of isn't passing in the traditional sense. Okay. So we've got this like relation of events as being just the nature of what time is. If people are struggling to imagine like, you know, they're sort of thinking, well, how can there be a beginning of time?

1:08:36Phil Halper:That doesn't make any sense. It's like, just try to think about the concept of time now when it does exist, try to define it, try to understand what it is and how it works and what it means. That is confusing enough. So like, I do think it's like a really difficult challenge to be thinking about the beginning of time, but maybe that's just a property of the weirdness of time as a whole. But okay, so maybe time has a beginning, but stuff is happening before time begins.

1:09:01Niayesh Afshordi:There could be. Yeah, we can't help but use this word before, right? Because it's part of our lexicon and we're used to the familiar world of our experience. But the early universe is nothing like the world of our experience. I think that thing, all of the different models would agree on. So forget about your everyday world. The Big Bang is going to be very, very different. And there are different notions of time within physics as well. So another is what's called conformal time. So an analogy here might be, imagine you play a chess game. So when people play chess, you might see them writing down the moves.

1:09:37Niayesh Afshordi:And you could put those moves in a sequence and you could say, well, it was six seconds elapsed between that move and that move. And maybe I had think about this one. So there was a minute between this one and this one. And conformal time would keep the order, but it would lose the scale. And Roger Penrose has a cyclic model of the universe that Neyesha's built upon. And this says, well, there's still conformal time, but there isn't the sort of normal time that we experience. So we don't have the scale of time, but we still have a sequence of events. So he has a cyclic universe that loses its sense of scale because Because it turns out that in order to have the time that we're familiar with, you need to be able to build a clock of some time.

1:10:18Niayesh Afshordi:And I don't mean a clock like my watch, but anything that could tell the time. But if there was no mass in the universe, which may be true in the Big Bang, it might be true in the far future, then you couldn't build a clock. So you would lose our normal sense of time, but you could still have this conformal time. So a very, very different notion of time.

1:10:39Phil Halper:Here's a problem, Phil. As you well know, if we're imagining this eternal inflation, so time stretches back infinitely, we've got our little pocket universe, but everything else just goes back infinitely and there's no beginning. As you well know from the study of the philosophy of religion, this is not possible. We cannot have an infinite past. A lot of people think that an infinite past isn't true because of the Big Bang and science, but maybe we can't be so clear on that. But philosophically, we can know it, right? Like William Lane Craig talks about this all the time. Al Ghazali proved this by just thinking about the fact that, for example, if the universe, by which I mean the whole universe, is past eternal, then there would have to be an infinite number of events in the past, which means that there would have had to have elapsed an infinite number of events before we got to today.

1:11:33Phil Halper:But you can't surpass an infinite number of events because it's infinite. And so if the universe is past eternal, we would have had to transgress an infinite number of events to get to today, which you can't do. But here we are at today, which means that the universe can't be eternal, right? No, not correct, I'm afraid.

1:11:54Niayesh Afshordi:I've actually made a documentary on this Kalam cosmological argument on my YouTube channel and interviewed lots of philosophers, including religious ones. And I think it's widely rejected, this argument. So let's see what's wrong with it. The idea is, well, if you start counting nought today, one tomorrow, two the day after that, you're never going to get to infinity. But if the universe is past eternal, then we would have had to have got to infinity. And it's certainly true that you can't get to the end of anything that's endless. That's right. But that doesn't mean you couldn't have an eternal past.

1:12:28Niayesh Afshordi:Because if the hypothesis is that the universe had a beginning, then there is no starting point. There's not a moment where you start at zero and then go one tomorrow, two the day after. Rather, there is no starting point. If the universe had no beginning. If it had no beginning. There is no starting point. So a lot of these analogies that I use to try and prove that the universe can't have a beginning sort of assume that there's a starting point infinitely far in the past, and then you start counting from there. And the idea is you can't get to infinity by just counting. I think what they're kind of assuming is that if you start with finite and you add more finite, you're just going to end up with a bigger finite number.

1:13:07Niayesh Afshordi:You're not going to have an infinite number. But the whole point of a universe that's eternal into the past is that you don't start with finite. It's always infinite. So this problem simply doesn't arise.

1:13:18Phil Halper:You understand the grammar of the problem, right? Which is that, okay, so there's no point at which you can start counting. But that's kind of the problem, which is that future events happen after the past ones. Past events happen before present and future events. and if there are an infinite number of past events and the future events have to come after that you understand the problem with imagining that somehow they're just have elapsed in the past an infinite number of events it sort of seems like we're at the end of this this chain like how how should we be thinking about it because the only other way i can think about it is like me right now looking infinitely forward and infinitely back that makes sense so you start with today which is zero and the past is more like minus one, minus two, minus three.

1:14:03Phil Halper:So there's no beginning to the past, and there's no end to the future. But then that seems to sort of metaphysically privilege the present, like me right now. Like, why is now zero? Well, it's not anymore, because time's just passed. So maybe now is zero. And zero sort of moves with me, which means that if all human beings died, there'd be no way to have that sort of privileged zero position from which to sort of look forward and back. So without sort of arbitrarily picking the present moment as our starting point, like objectively, there's no way to even start like counting at all. There's no way for me to count today and tomorrow because there's just no starting point.

1:14:38Phil Halper:You know, like it's just like impossible to wrap our heads around. Why would you say it's your privilege if everyone else sees the same thing that you see? Well, for a few reasons. Firstly, because it's not clear to me that like everybody else is seeing the same thing as me because time doesn't move linearly, right? So my zero wouldn't be the same as your zero. But also just like metaphysically, right? I mean, if we're talking about the actual nature of the universe, which means that it's easy for us now, alive human beings, to sit here and go, okay, well, let's just consider now as our starting point for our knowledge.

1:15:12Phil Halper:And our knowledge stretches infinitely forward and infinitely back. And there's no problem with that, you know? No beginning, no end. Cool. But in order to have that starting point of now, we need to exist. We need to exist in time to think of it in those terms. if there were just like no human beings if our universe never popped into existence or if we all just died there'd be no conscious agent to say all right now is the present and we're going to think forward and back but there still would be like an answer to the question of whether the universe had an infinite past or not but there'd be no people to to pick sort of zero as the present right because there'd be no one experiencing the present there would just be an answer to whether there have been an infinite series of events or not.

1:15:54Phil Halper:You know, I don't really know how to wrap my head around the idea that past events come before future events. And yet, like we can sort of stretch that infinitely.

1:16:06Niayesh Afshordi:I think we can all agree that this is hard to get your head around. But it's true whether the universe had a beginning, that's hard to get your head around. Or whether it didn't have a beginning, that's also hard to get your head around. I think it was the philosopher Kant that said that he could prove that the universe couldn't have a beginning and that it must have a beginning, right? Because it's just, it's very, very difficult to think about. So I think we can all agree on that. But this idea of now, of course, in relativity, there is no unique now that the universe has to get to. So I think this is not something that we have to worry about.

1:16:43Niayesh Afshordi:Now, could the universe be eternal into the past? There's no contradiction with that. Now, some people say there's actually a contradiction, you know, William Lane Crowe. Yeah, like the Hilbert's Hotel.

1:16:52Phil Halper:Anytime you introduce the concept of infinity, it leads to paradoxes.

1:16:57Niayesh Afshordi:Well, what it leads to is counterintuitive answers, but they're not actually contradictions. So let's take an example of something that's claimed to be a contradiction.

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1:17:29Niayesh Afshordi:A upfront payment of$45 for three-month plan,$15 per month equivalent required. New customer offer first three months only. Then full price plan options available. Taxes and fees extra. See mintmobile.com. Try and show why it isn't. So people may be familiar with this notion of the Hilbert Hotel. This is going back to the mathematician David Hilbert. Although, ironically, it was the physicist Gamow, who was one of the defenders of the Big Bang, who used Hilbert's Hotel and popularized it. Because I think Hilbert mentioned it once in a lecture and that was it.

1:17:55Phil Halper:Yeah, interesting.

1:17:56Niayesh Afshordi:And what Gamow was trying to say was, look, the universe could be infinite and expand. Because it sounds really strange. Well, if it's infinite, how could it get any bigger? But he said, no, no, no. Hilbert's Hotel shows that it can. Oh. So in fact, the universe... And he was trying to say, look, the universe could be infinite and expand.

1:18:12Phil Halper:So Hilbert's Hotel is the idea of this hotel with an infinite number of rooms, right? Just like an endless number of rooms. And every room is occupied. And so somebody shows up to the hotel and says, I'd like a room, please. And they go, sorry, every single room in our hotel is occupied. And they think, well, actually, I've got a solution to this. All we'll do is we'll take person in room number one, and we'll ask them to move to room number two. Person in two moves to three, three, four. So everyone just moves one number up. And because there are infinitely many rooms, there's always the next room that a person can go to.

1:18:43Phil Halper:So we say, okay, we've got a room for you. And they put them in room one, which seems like a paradox because every room is full and yet there is a room for every single tenant to sort of move into. And so the William Lane Craigs of the world look at this and say, that's a paradox because the place is full. He always says, oh, it would have to say, you know, what is it he says? Like no vacancy, guests welcome on the front, which is a paradox. But are you telling me then that this is sort of originally formulated as a way not to say, look how counterintuitive this is, so it's impossible, but rather look at how I can prove the possibility of this really counterintuitive thing that infinite things can expand?

1:19:29Niayesh Afshordi:Yeah, that's exactly why it was popularized. I mean, Hilbert didn't think about this, But as I say, I think my understanding is he gave one lecture about it and never mentioned it again.

1:19:37Phil Halper:He does so often like, it's so interesting how these ideas embed themselves into popular culture, sometimes for the complete opposite reason. Like you mentioned Schrodinger's cat earlier, Naiesh, which a lot of people think they're like, I've heard of this. Doesn't quantum mechanics prove that the cat is dead and alive at the same time? Not realizing that Schrodinger invents it as basically a way to mock this interpretation of quantum mechanics. To be like, look how ridiculous this idea is. But the way it's embedded itself in popular culture is like, oh, look how Schroding proved that the cat is dead and alive at the same time.

1:20:05Phil Halper:It's completely on its head. And maybe this is another example of that. Yeah. This was an attempt to prove that we could have an infinite universe. Right. That still expands.

1:20:13Niayesh Afshordi:Yeah. That still expands. Yeah. So let's just go to the notion that it leads to a paradox or a contradiction. Yeah.

1:20:18Phil Halper:Sure. Okay.

1:20:19Niayesh Afshordi:So two things. One is the paradox of how can a hotel that's full accommodate new guests? And we're used to our intuitions to say, well, that's impossible because the universe that we know, all the hotels have a finite number of rooms. So, of course, they will eventually run out of space. But an infinite hotel simply cannot run out of space. There's always the next number. So it's an equivocation on the word full. If what you mean by full is someone in each room, then yes, the Hilbert Hotel can be full. But if what you mean by full is can't emit new guests, then the Hilbert Hotel cannot be full.

1:20:56Niayesh Afshordi:It can never be full. So the Hilbert Hotel can always emit new guests. Now, the other thing that's claimed is that there's a contradiction, because let's suppose we take out all the even number of guests from the Hilbert Hotel. How many have we got left? Well, we've got infinitely many. So we took away infinitely many, and we've got infinitely many left. So infinity minus infinity is infinity. But now, let's say all the guests in room number four and above check out. Now we've taken infinitely many guests out, but we've got three left. So, infinity minus infinity is three. So, it looks like, and Craig in a video said this is a contradiction.

1:21:32Phil Halper:Yeah, because from that you can derive that, you know, one equals two.

1:21:35Niayesh Afshordi:Yeah, exactly, exactly. But this is just wrong, because infinite sets have different properties to finite sets. So, in a finite set, you don't have to specify which thing you took away. So, there's a table in front of us now. There are three cups in some sense, two glasses of water and a cup of coffee, was it Alex?

1:21:55Phil Halper:It was, yeah. Right.

1:21:56Niayesh Afshordi:Okay. So if I said that there's three of these things on the table and I take one away, you don't need to know which one, whether it was one of the glasses of water or the cup of coffee away. You know I take one away, there's two left. But for infinite sets, you have to specify which things you took away. So once we specify which things we took away, well, we didn't do the same operation. When we took the even number of guests away, that's one operation. When we took all the guests in room four away, that's a different operation. They are not - You can't just say infinity.

1:22:27Phil Halper:It's like the difference between saying, okay, so there's a coffee and two glasses of water on the table. If you say, okay, well, if I take one away, I'm going to take this glass away. How many glasses of water are we left with? One. Okay, right. Let's go again. Now I'm going to just, again, I'm just going to take one away. This time I took the coffee away. So how many glasses are left on the table? Well, there are two glasses of water on the table now. So in both cases, I've taken one away, but one's given us one glass of water and another has given us two glasses of water. Yeah, because it depends what you take away.

1:22:57Phil Halper:You can't just take away one. You have to take away one of something. You can't just take away infinity. You have to take away a particular set of infinite things, a particular kind of infinity, right?

1:23:07Niayesh Afshordi:Yeah. So infinite sets have different properties to finite sets. And I think the power of this argument is that it carries off your intuitions about finite sets. And you think that the finite sets must have the same properties as infinite sets, but they don't.

1:23:23Phil Halper:Okay. Niaesh, what's your thoughts on this? What do you think about the plausibility of an infinite past? Do you place stock in it? Do your intuition scream at you that there must be a beginning?

1:23:34Niayesh Afshordi:Yeah. I mean, infinity is all over mathematics, right? So it's, I mean, all this stuff, I mean, we talk about it at high school or middle school or whatever, but you don't do stuff with infinity that you do with regular numbers. It's just no-no. And yeah, I mean, it's a perfectly fine part of math if you know exactly where it comes and what to do with it. When it comes to physics, I mean, again, we build physics using mathematical language. So same places that there's infinity in math, there's infinity in physics because it's just the same thing. Right. But then the question is, yeah, So where are the places in physics where infinity cannot be?

1:24:17And if I'm measuring something, like I'm measuring the time or temperature in this room or anything I measure,

1:24:24Niayesh Afshordi:it doesn't make sense to say that I measure infinity. So those are the places where infinity is not allowed because that's not a real number. That's not a measurable number, right? anywhere else it's fair game because I mean as long as it appears somewhere that it's not directly prediction of a measurement and I can still do my predictions like I can make calculations right there's really no problem with infinity so as long as I have a way of dealing with it right so that's the thing now that being said having an infinite time is kind of rubs me the wrong way because it's kind of the same as a multiverse right as you're saying that okay there's an infinite universe infinitely many pockets with various properties i don't have access to it it sounds like science fiction but also it kind of feels that it goes beyond the realm of physics because i cannot really constrain them and there's no testable prediction and of course this is some this is a controversial topic an exciting area of debate that okay this multiverse testable or not, and we do talk about some of the potential ways of testing it.

1:25:35Niayesh Afshordi:But, I mean, for the most part, it's either untestable or very hard to test. Infinite time is kind of the same, right? This is in my view, because if there are things that happened a very long time ago, like long before the hot big bang that we see, I mean, were they there, were they not there, does it matter? So we could talk about it from a mathematical standpoint, but is it part of our physical language or should it be part of our physical language? And that's the part I'm kind of more skeptical, which is, yeah, it kind of goes hand in hand with skepticism, eternal inflation, and multiverse.

1:26:11Niayesh Afshordi:So my own favorite, so I think we talked about Hartle-Hawking model where there is time begins to exist at some point and didn't exist before some time. We work on a different model called holographic cosmology with Kostos, Skanderis, and others. Holographic cosmology. That's right, holographic cosmology. So holography is this very exciting part of theoretical physics which actually came out of a string theory in the past 30, 40 years. And the idea is that maybe if you want to describe gravity in a quantum sense, you shouldn't think about gravity in a space and time. You should kind of think about boundary of the region and think about quantum mechanics in the boundary.

1:26:57Niayesh Afshordi:So there is this idea of holography that really understanding gravity is like understanding quantum mechanics in one lower dimension, which is like holograms. It seems like you see something three-dimensional, but it's really two-dimensional. So one way to describe it is that maybe one of our dimensions, it could be one dimension of space or one dimension of time, is kind of an illusion. Okay, pause.

1:27:21Phil Halper:So a holograph. Yes. People are familiar with these things. like you get them at like, you know, little stores on the side of the beach, wherever it's 2D plane, but it kind of looks 3D, right? You look at it with angles and it shifts and it moves. It is actually 2D. It's actually 2D. It has the appearance of three dimensions, sort of move around it. The idea of holographic cosmology is the idea that one of our dimensions of time, or one of our dimensions of space, or maybe the dimension of time, works in a similar way. That there's actually only two dimensions, and the third dimension is a holograph or there's only three dimensions and the dimension of time is a holograph.

1:27:58Phil Halper:And so they're forced like an illusion?

1:28:01Niayesh Afshordi:This is a good question. So now illusion is a kind of depends on your definition of reality, right? Now, our three-dimensional kind of description in this room, we're talking, we're moving around, up, down, left, right. We can wait, so move forward in time. So that description of three space and one time works very well. So you may think it's an illusion, but it's a very good illusion. It's a very, very convincing illusion. There might be a different description of this room without one extra dimension. You could imagine it exists. It's just very contrived and a strange description of these events that are happening if you don't use, say, one of the dimensions.

1:28:46Niayesh Afshordi:It's possible, but it's just not very convincing. And the idea, this modern idea of holography is that really there are two ways to describe things. One of them might be easier, at least in some language, in the language that we're familiar with. But that depends on the situation. And we know there are situations where this three-dimensional description becomes very contrived. and those are near singularities, right? So these places where quantum gravity plays a role, where basically there are strong fluctuations in geometry. You could have black holes popping in out of vacuum. You have very strong curvature.

1:29:30Niayesh Afshordi:So these are places where we really understand quantum. We need to understand quantum mechanics and gravity playing together. And right now we don't. So in such situations, in fact, a more satisfactory, more kind of simple to describe language is a language without one of those dimensions. Now, this dimension you're taking away, it could be a dimension of time or it could be a dimension of space. And depending on the set of the problem you're trying to solve, the kind of singularity that you're dealing with, it could be a dimension of space that is easier to take out of a dimension of time. And for the Big Bang, this holographic cosmology, the idea is that when you get close to the Big Bang or Big Bang singularity, if you want.

1:30:14Niayesh Afshordi:So past the hot Big Bang, maybe close to Big Bang singularity. This is where this 3 plus 1 dimensional description breaks down. And maybe you just have three dimensions of a space. No dimension of time. No dimension of time.

1:30:29Phil Halper:Just dimensions of space.

1:30:30Niayesh Afshordi:Just dimensions of space. So that's another, that's an example of the, basically you have regular time all the way down to some point. And then at that point, it's not that the time stops to exist. It's just that your description, your stories in terms of time becomes more and more convoluted.

1:30:49Phil Halper:Is this version of time being like an emergent property?

1:30:51Niayesh Afshordi:That's the idea. So in this case, time would be emergent.

1:30:54Phil Halper:So as you go towards the Big Bang, it gets to a point where it's not that time ceases to exist, but you're operating on a level where this holographic illusion, if you like, of time, it just sort of doesn't apply in the same way that temperature is an emergent property, in that things are hot and things are cold. But if you go small enough down into the atoms, you realize that temperature is just atoms vibrating. And an atom vibrating is not hot or cold in itself. You have to zoom out before you get this concept of temperature, which is emergent. A cake is spongy. But if you zoom in and look at all of the atoms it's made of, none of the atoms are spongy.

1:31:31Phil Halper:You have to zoom out. And it's not like when you start zooming in with a microscope to this cake, sponginess just disappears. it just you're operating on a level where it just hasn't emerged yet and time might be a property a bit like this where not so much zooming in but going backwards towards this big bang singularity time as an emergent property just sort of doesn't apply here or something like that that this is an

1:31:54Niayesh Afshordi:excellent analogy in back there is a they have a technical word for exactly the zooming in and out it's called holographic renormalization holographic renormalization i prefer the cake thing Well, I mean, Phil has a video about holographic normalization. Phil's got a video about everything.

1:32:14Phil Halper:That's right. Is this how, I mean, one phrase that we often hear, especially in popular apologetics and just general discussion is that the laws of physics break down at the Big Bang. And this often is used to indicate this impenetrable epistemic boundary that we can't really discuss or talk about the Big Bang scientifically because that's where our laws of physics break down. Is that true? Is there a sense in which that's true? And if it is true, does it place the Big Bang outside of scientific apparatus if science relies on laws to explain the universe and these laws break down at the Big Bang?

1:32:55Phil Halper:you know what I mean? I mean, it sounds a little bit like when time stops existing, it sounds like, you know, physics beginning to break down. But I don't know, you must have heard this language. Yeah, of course. Do you think it makes sense?

1:33:04Niayesh Afshordi:I think the case is that it's general relativity that breaks down at the Big Bang.

1:33:11Phil Halper:Interesting. Okay.

1:33:11Niayesh Afshordi:So it's not necessarily the laws of physics break down, but rather the laws that we have break down. And what people like Nia Yash and other cosmologists are trying to do is to expand what those laws are to sort of give us new laws in the same way that We had Newtonian physics and then Einstein gave us new laws. But new laws came into existence, as you pointed out. Alan Guth didn't invent the inflation. He invented the theory. So this is what physicists and cosmologists are trying to do. They're trying to discover the laws that actually hold at the Big Bang. So Stephen Hawking famously said that in his No Boundary proposal, the laws of physics would hold everywhere.

1:33:49Niayesh Afshordi:There's nowhere where the laws of physics break down. So this is what we're trying to do. We're trying to push our envelope of knowledge to go beyond that point where they break down. And this is where the controversy is, and this is what the battle of the Big Bang is all about, because we don't know what those laws are. There's lots of proposals, there's string theory, there's loop quantum gravity, holography, all kinds of ideas. And so we don't know which is the right law to use, but that doesn't mean the laws themselves break down. They may always exist.

1:34:21Phil Halper:That's interesting. I mean, I kind of wanted to get to this in a moment because I wanted to talk about universes coming into existence out of nothing. But like, uh, the Lincoln has this idea of universes that can pop into existence out of nothing. And in your book, you talk about how there's this criticism that you've made to him in your video that this would require these laws of physics to like exist before the universe came into existence. Because if you imagine like the universe cropping into existence from some quantum fluctuation, that means the laws governing quantum physics must predate the universe.

1:34:56Phil Halper:And Verlinken says that he just thinks that the laws of physics just exist as a platonic object. They're just these things that just definitely exist. That's definitely not my view of the laws of physics, but it does lead to this interesting question of like, it does seem like there needs to be something exterior to all of this, right? I would say that even if the universe were past eternal, there's still a good argument to say that it requires some kind of sustaining cause. And this is something which someone like Aquinas agrees with. I think Aquinas thought that the universe did have a beginning, but he also said that even if it didn't have a beginning, it would still need some kind of cause.

1:35:34Phil Halper:So maybe I can begin by asking, and maybe this is a question more for Phil, I'm not sure. If the universe did have a beginning, if we did know that it did have a beginning, either the beginning of universal inflation or there is a Big Bang singularity or something, if it did begin to exist out of nothing do you think it needs a cause uh personally my opinion

1:35:55Niayesh Afshordi:is no we certainly can't demand that it must have a cause okay um older idea of the universe from nothing that goes back to edward tryon and when people sort of make criticisms of the idea of universe from nothing they say that's not nothing that's not nothing because that's a vacuum and and neil esch talked about the vacuum is not nothing vacuums can't be it's got all kinds of activity in it. But what Vilenkin suggests is something quite different. Here the idea is, well, what if we treat space-time or space itself quantum mechanically? Then his idea is that space itself would fluctuate into existence.

1:36:30Niayesh Afshordi:So it's not coming from a vacuum. Where's it coming from?

1:36:34Phil Halper:In his view, it's coming from a state with no space. Okay, so just to be clear, when I say nothing, I'm talking about, as Aristotle said, what rocks dream of. I'm talking about what you see out of your elbow. I'm talking about nothing, right? And even to say from nothing, the way that I've pictured that in my head is I imagine sort of darkness and then something pops into existence. But no, there's no space, there's no extension, there's no anything. But that's right. In Vilenkin's model, there is no space.

1:37:05Niayesh Afshordi:You've been involved in philosophy of religion, Alex. And you'll be familiar with the idea that God created the universe ex nihilo, no materials. So that's what we're talking about here. It's exactly analogous. The universe has created ex nihilo, nothing material that we know of, nothing like anything you can see in this room, not even a vacuum.

1:37:26Phil Halper:So no space. So Phil, why aren't you worried? If you think things can begin to exist without causes, then why aren't you worried, as the common line of argumentation goes, that a deer has just spontaneously begun to exist in your kitchen and is currently destroying it. Shouldn't you go and check?

1:37:41Niayesh Afshordi:Well, I asked Vilenkin this. I sat in his office and I asked him, I said, why can't a tiger just appear in this room? And actually he said to me, well, tiger could appear in this room. You know, there's a quantum probability of that.

1:37:53Phil Halper:Yeah, that is true.

1:37:53Niayesh Afshordi:Right. But it's just unimaginably unlikely. So no need to worry about it.

1:37:57Phil Halper:But that wouldn't be out of nothing, right? That wouldn't be out of nothing. So why aren't you worried that a tiger might pop into existence out of nothing, not as a really unlikely quantum fluctuation of atoms or whatever, but out of just like nothing. There's no space, there's no nothing. A tiger just appears. Why aren't you worried that that's going to happen right now?

1:38:16Niayesh Afshordi:Well, we're not in nothing. So if it can come out of nothing, well, that's not where we are. We're in this universe, so it has to play by the rules of this universe. Now, the question is, could a tiger appear out of nothing, like empty, not empty space, sorry, just no space. Well, what Vilenkin tried to do was to use inflation and say, look, the probability of a universe coming out of nothing and actually lasting is incredibly small. But what he suggested, and this is why it's called tunneling from nothing, that it could tunnel to a state where it would then inflate and become a big universe. So if it was just a tiger with no inflating energy, then it would just go back into nothingness as it were.

1:38:57Niayesh Afshordi:Sure. So now let's go on to this issue of causality. Yeah. So if the universe came from nothing, would it need a cause? Now, what I want to do is ask the question, well, let's suppose God created the universe. Does God need a cause? And what's often the reply is often, well, God doesn't need a cause because God doesn't have a beginning. God doesn't necessarily exist. God doesn't have a beginning. It's only things that have beginnings need causes. That's how the Kalam. Okay, yeah. So that's in the Kalam argument. Now, that's not the statement that God exists eternally into the past, right? But rather the claim is that God exists timelessly and then enters into time.

1:39:41Niayesh Afshordi:But now let's go back to Nea Aesha's holographic cosmology model. That also exists timelessly and then enters into time. And we might make an argument for the Hartle-Hawking model, which also has a timeless state. So here, maybe then we could say exactly the same thing, where it doesn't need a cause, right? So the question is, like we said about water being emergent, causality may be emergent. So then when we get to the quantum realm, maybe causality doesn't exist, that causality is a feature of our macroscopic universe. So we can't assert that these things must have causes because we don't know if causality is fundamental.

1:40:17Phil Halper:This is kind of like a version of when people say, well, the universe needs a cause, and that cause must be God. There's some kind of first cause or some kind of necessary existence. And a very common response to this from atheists is to say, well, in some sense, the universe can serve that role. The universe is this brute fact. The universe necessarily exists. People come along and say, no, the universe doesn't necessarily exist. It had a beginning. How do we know that? Hilbert's Hotel, the Big Bang. We've gotten rid of those ideas, right? So let's say that we can no longer dismiss the idea that the universe is this fundamental thing from which everything else stems.

1:40:55Phil Halper:And all of the qualities that exempt God, I think legitimately, by the way, philosophically, I don't think it's a cop-out to say, well, God doesn't need a cause. I think that's perfectly philosophically legitimate. What we're saying now is it might be equally legitimate to apply that to the universe or whatever sort of was the Big Bang or before the Big Bang. here's the question and this might be a question for you naish because you've got this holographic view of time and earlier this is what i was trying to wrap my head around time doesn't exist and then it like does exist here's what the theists say and here's what i say when i'm on my on my sort of theist day on i say okay so we've got this timeless cause but we've got a temporal effect right the universe which has popped into existence is it has time it's got a temporal effect but the cause is existing timelessly in a sense it sort of exists you might want to say infinitely maybe not eternally but definitely timelessly timelessly here's the problem right if you've got a timeless uh cause it just exists timelessly forever there's no like beginning to it it just exists i used to set forever so that doesn't mean time exists outside of time there's no point in time at which it doesn't exist.

1:42:08Phil Halper:Let's say that. If there's no point in time at which this cause doesn't exist, if that cause is causally sufficient to bring about an effect, imagine it entails the effect. Imagine the cause entails the effect. If you've got a cause which has the ability to bring out an effect, and that cause exists, there's no point in time at which that cause doesn't exist, then since that cause brings about the effect, there should be no point at which that effect doesn't exist because the cause brings about the effect. The cause is timeless. So the effect should be timeless too. In order to have a timeless cause that yet brings about an effect at a point in time, that cause needs to like do something.

1:42:53Phil Halper:It needs to have, in other words, as a theist would say, a will or it needs to have some kind it can't just be this inert law because laws apply all the time right laws laws laws don't sort of change fluctuate so you've got this no point in time at which the cause doesn't exist there should be no point in time which the effect doesn't exist but if there is a point where the effect doesn't exist but no point at which the cause doesn't exist the cause must do something must have some kind of will we're looking at something that looks a bit more like god than some foundational law of the universe right you get what i'm saying

1:43:25Niayesh Afshordi:Yeah, it seems to me that it's kind of getting more complicated than it should be. I mean, I guess that this timeless story, maybe, I guess maybe we misstated it. So I guess it's timeless in the sense that in this earlier state, there is no time. There's only a space. But you could also say that it exists at one time. So it's not that it exists all the time. So this initial state, this three-dimensional timeless state, it's not that it exists eternally. It just was there. That's a proper way of understanding the universe at early times. Now, here's the thing. It's not that there is one or the other, right?

1:44:12Niayesh Afshordi:So I think you're kind of separating the cause from the effect. And I think maybe, okay, so maybe in a kind of roundabout way, I kind of agree with you because the idea of holography is not that one is real or the other is not real. So the idea is that there are two different descriptions. There is one description with time and there's another description without time. And there are equivalent descriptions. There's not one, neither of them is higher or better or different from the other. There are the same descriptions. they're just easier to kind of put it in human language or mathematical language in some situations one is easier in one situation the other is easier in other situations but nonetheless they're equivalent okay so in that sense i think i agree with you that if you want to say one of these is the cause the the timeless one is the cause and time time full one is the effect then are in fact the same things.

1:45:09Niayesh Afshordi:So we are the gods. Is that right?

1:45:13Phil Halper:Well, you know, I really thought we'd get to the end of this without any kind of blasphemy. We just about managed to step it in. Okay. That's interesting. And of course, a model like this holographic universe is, even if we spent the whole podcast talking about it, there's too much to go into, which is why once again, I will wave the book around and and implore people to go and buy it. I mean, Carlo Rovelli on the front cover describes this as an intellectual feast, and I think he is right. It is phenomenal. So many questions left unanswered. I mean, one is to say that like, okay, so we were just talking about this.

1:45:50Phil Halper:Phil, recently Joe Rogan went viral for saying that he's, quote, sticking with Jesus. Reason being that the difference between science and religion is that science only asks you to believe in one miracle, that the universe just sort of pops into existence out of nothing. Okay, maybe that relies on this idea that the universe has a beginning at a point in time, which as we've discussed, it might not. The universe might be infinite. But as I said, even if the universe is past eternal, it still seems that there would be some reason why that eternal thing exists. And so Joe Rogan says that the miracle that the scientists ask you to believe in is that the universe just sort of exists for no reason or out of nothing or however you want to think about it.

1:46:36Phil Halper:And if you think it's so ridiculous to believe in the miracle of the resurrection, isn't it equally ridiculous to believe in that kind of miracle? And isn't science therefore ultimately based on a similar kind of faith?

1:46:47Niayesh Afshordi:Well, let's separate the two miracles, right? One is that the universe came from nothing. And I think we can say for sure that we don't know that to be true. So it's not impossible. Vilenkin has this interesting idea. But as we explored, there are lots of interesting ideas. And we have to embrace the uncertainty. I think that's kind of the theme of the book, is when people tell you, you know, the universe came from nothing or it had a beginning or all kinds of ideas, embrace the uncertainty because we don't know, right? So we can't say the universe came from nothing. So Joe Rogan, I think, is just misstating the case here.

1:47:20Niayesh Afshordi:but that doesn't mean we shouldn't address this issue of what's the reason that the universe exists so another interesting model that we haven't talked about too much is this idea of a time loop and interestingly this would say this would also challenge our notions of cause and effect right because what's the cause and what's an effect if we're on a loop in time and William Lane Craig said that this was a desperate attempt by atheists to to avoid God but what he didn't know is that Richard Gott, who came up with this model, is actually a believer. So the question might still be, well, why does the universe exist?

1:47:57Niayesh Afshordi:And I think what we can do in cosmology is not necessarily to answer these really big questions. I mean, that's for philosophers. And what cosmologists want to do is push the envelope of our knowledge. So we've got a point, the Big Bang, where our knowledge currently sort of stops. And what cosmologists want to do is push beyond it. And that's the battle. But I don't think that's going to give us answers to why does the universe exist. I mean, you can try and make inferences about it. Like if we look at the Vilenkin tunneling from nothing model, you could say the universe exists because the laws of physics exist.

1:48:32Niayesh Afshordi:And maybe the laws of physics are necessary. Maybe they just couldn't be anything other than what they are. So if you're looking for the necessary thing, maybe it's not God, maybe it's the laws of physics. And I kind of like that better than God, because we know the laws of physics exist in some sense, now exactly in what sense they exist, that's the thing for debate. But I like that better than God because I think, well, laws of physics seem more parsimonious. But of course, this is a speculative idea. And maybe there is no reason. Maybe it just is. And I think Bertrand Russell just said, the universe just is, and that's it.

1:49:08Niayesh Afshordi:So I don't think cosmology is going to settle those questions. But what it can do, what we hope it will do, is push the edge of our knowledge from just after the Big Bang to maybe before.

1:49:18Phil Halper:So Joe Rogan might have the wrong idea of what the Big Bang is and what you're required to believe to accept the Big Bang, but it's not illegitimate of him to go, but look, at least the kind of scientist that says, well, the Big Bang has done away with our need for religion and sort of has explained everything. Actually, no. In order to think that the Big Bang has somehow explained the beginning of the universe, you kind of are believing in some kind of miracle, if at least the miracle of explanation, which scientists just cannot even begin to approximate right now. Is that putting it too strongly?

1:49:54Niayesh Afshordi:I don't know if I'd want to use the word miracle. There are certainly unanswered questions that I think physics is not setting its task to answer.

1:50:04Phil Halper:Do you think Joe Rogan is embodying an illegitimate criticism there as a whole, which is to say, okay, maybe he's got the wrong model of the Big Bang or whatever. But even if we corrected that and said, you know, Rogan, like maybe the universe didn't come from nothing. Maybe it's past eternal. He goes like, oh, okay, that's interesting. But like, man, like still there's this question of like why it exists. And the scientist is just asking me to just accept that there is some reason that we just don't know. And it's like, man, I'm sticking with Jesus because that's more sensible to me.

1:50:34Niayesh Afshordi:Well, we asked you to embrace the uncertainty and sticking with Jesus is not embracing the

1:50:39Phil Halper:So you're not asking someone like Joe Rogan to say, don't stick with Jesus, stick with the quantum loop theory, because that's the correct. It's rather don't stick with Jesus because we don't know what to stick to yet. Maybe it's Jesus. And maybe if it is Jesus, science isn't the method we'll use to find that out. But the resistance to this religious impulse is not because you have a better explanation, but just because you have alternative explanations and we don't know which one is the correct one i think that's fair enough perfectly yeah naesh do you have a view on this

1:51:13Niayesh Afshordi:uh yeah i mean i think this is just a misunderstanding of um kind of scientific methods saying that we asked i mean a miracle of course is a loaded word depends on i guess if you're religious or not it depends you you feel differently about it uh but uh anything is you asked this earlier that okay does the rules break do the rules break at the big bang or do And I was going to say, and I can kind of say that again, like 150 years ago, the rules of physics broke at the surface of the sun. So, yeah, what's got there?

1:51:50Phil Halper:Yeah, at some point, the laws of physics broke near the speed of light. Yeah. The laws of physics broke, you know, with really, really heavy objects.

1:51:59Niayesh Afshordi:That's right, absolutely. At various stages in the development of science, we had certain rules or laws, approximate ones, and they were very good in some domains, and then we pushed them and pushed them. At some point, they broke down. 150 years ago, that was the surface of the sun. And then we learned about relativity, learned about nuclear physics, and then we could then explain how plasmas behave, how convection works in plasmas, and how nuclear fusion works. Now that point is near this Big Bang singularity or a hot Big Bang. Are we making progress? I think we are making progress. I think we're pushing further.

1:52:36Niayesh Afshordi:But I mean, it's kind of an arbitrary point to say that, okay, so now this is where science is going to end here, definitely. And yeah, it could have ended, I suppose, any point in the past 300 years at any point where it is. But it hasn't. It's been making progress, essentially, and we're doing the same things. but I think about kind of broader implications of whether I mean is there room for religion in science I think there is I think this is more of an evolutionary question as opposed to maybe scientific well I mean still a scientific question but maybe science of humans not science of cosmology which is to say that I mean cosmologists are humans and humans have lived with religions for for thousands of years, if not longer, as far as we know in written history.

1:53:22Niayesh Afshordi:So the question, and this is the question I like to ask, that you can take a cosmologist out of religion or out of religion, but can you take religion out of a cosmologist? I mean, if this is something that's built into our DNA, because I'm not Christian, I'm not Muslim, I'm an atheist, but then you're still living life the same way your ancestors have been living. And the surface is very different, but we are still drinking water. We're still breathing air. So certain things in our brain may work the same way. And maybe we kind of develop religions in new senses, like, for example, is inflationary cosmology or a string theory modern day religions?

1:54:09Niayesh Afshordi:And we kind of go into lengths to what extent that question even meaningful, right? that maybe in some sense there are similarities, but then also there are differences. I mean, where we do make connections to experiments or nature, we pose testability or falsifiability as a criterion. Maybe that's where we try to distinguish ourselves. But I mean, this is a very fuzzy kind of gray area, exactly where science becomes religion or vice versa. So I think that's one thing that I think religion, as much as we may want to distance ourselves from ancient religions, I think this is part of our society, and it may show up in different guises in terms of dogmas or in terms of the way we build communities.

1:55:04Niayesh Afshordi:I mean, religion has been used to build communities for thousands of years, and we build communities among scientists, are we using similar practices?

1:55:13Phil Halper:Yeah, science is not immune from dogma. This is the point. And in fact, we were just talking before we shot about how, is it chapter 10 of the book that talks about the relationship to religion and science? And you want to ask the question, as if I just asked to you, Phil, is there space for cosmology within religion? Does cosmology sort of fit within this religious picture. The question you want to ask there, Naiesh, is there space for religion in cosmology? Right. At least those elements of religion which involve dogma and faith and belief without evidence, that can occur in science too. And the history of science is littered with people who are unable to accept consequences of particular ideas because of essentially dogmatic assumptions.

1:55:58Phil Halper:Famously, Einstein's blunder, I talk about that a lot on my show. Ironically, maybe he was right, you know, in a way he didn't realize. But the idea that, you know, his theory of general relativity showed that the universe had to be like, uh,

1:56:13Niayesh Afshordi:Well, he believed that the universe was eternal and static, but general relativity, he said that it would all collapse.

1:56:18Phil Halper:And so he introduces this cosmological constant which holds it in place. And then when he realizes that the universe is actually expanding and not static, he's like, I was so silly. He takes it out, he calls it his greatest blunder. And it was because of a philosophical commitment that he wasn't sort of willing to let go of. And philosophical commitments have gotten in the way of science, not just like religious institutions standing in front of scientists and saying, you know, you shall not have this. enter, but scientists themselves are unable to shake certain conceptions. And one of my favorite things that I've just thought about that you do in the book, when you're talking about the multiverse in particular, and this idea that the multiverse is ridiculous, and it's so silly and speculative, and as if there are billions of multiverses, like, come on, universes.

1:57:01Phil Halper:And you very briefly, in one sentence, track this history of science where you say, well, it used to be that the Earth was special and there were no other planets. Then we discovered actually there are other planets. But our sun is really special. We realize that the planets go around the sun and our sun is this really special object, separate from all the stars. And then we looked at the stars more closely and we realized actually there are billions of suns and all those little stars are actually the same as our sun and there's nothing special about it. And then we thought, okay, but like all of these stars are sort of collected into this galaxy and there's this one galaxy that we all exist in.

1:57:32Phil Halper:And then we started seeing these fuzzy objects in the sky, which Kant calls it an island universe. People are like, no, no, no, it's some kind of weird star or something. And then thanks to the work of the Harvard computers, some very, very undersung heroes, women who were doing the calculations that allowed us to discover, because of a particular kind of star in those fuzzy patches, that actually those fuzzy patches are galaxies as a whole. So first the Earth was special, then it wasn't. Then the Sun was special, then it wasn't. Then our galaxy was special, then it wasn't. There were lots of galaxies.

1:58:05and now our universe is special where's this heading you know i don't want to to extrapolate

1:58:10Phil Halper:unfairly but it seems at least plausible one day one day we will look back in the same way as we look back on those instances of science and people who are unwilling to accept that as a conclusion may just be beholden to philosophical ideas not to say that you have to accept it's true but if you are just unwilling to entertain its plausibility because it's just ridiculous think how many times that has been said about so many scientific ideas, to the extent that scientists have been laughed out of the room. The first guy to look at the continents and think, you know, it kind of looks like the America's slot into Africa and Europe, laughed out of the room.

1:58:48Phil Halper:And yet we now know that to be the case. I think it's a good reminder. And I think reading a book like this, as I say, it's in part of history, going over the history of this happening over and over again as a reminder to be like, we just don't know, man. We just have absolutely no idea. Maybe we will one day, but for now at least, I think this is the best we've got. And I think this is one of the best overviews available in print. It probably is the best available. I should have said the best available. Honestly, guys, I told you this earlier. I think the book is a triumph. I think it's phenomenal.

1:59:18Phil Halper:It's gripping. It's so well written. It doesn't have any bloody maths in it, which is awesome. And it covers all of this kind We didn't even talk about whether you can create a universe in a lab. We didn't talk about quantum loop gravity. We didn't go into all the implications of causation and religion and stuff. I mean, how many chapters is it in total? 12 chapters. String theory. The big bounce. You know, we didn't talk about the big bounce and, you know, timer shaped universes and universes that are self-causing. It's all in here. And perhaps we'll have to do this again sometime to cover it even more.

1:59:52Phil Halper:But I can only recommend that people go and read the book. It's out now, right? It's out now. The link is in the description. So yeah, everyone go and check it out. But guys, thank you so much. It's been fun.

2:00:01Niayesh Afshordi:It's been an absolute pleasure, Alex. Thank you so much.

2:00:03Phil Halper:It was wonderful. Thank you very much, Alex.