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

Episode Date: August 4, 2025

Niayesh Afshordi is a professor in the Department of Physics and Astronomy at the University of Waterloo. Phil Halper is a science communicator and YouTuber. Together, they have authored a book called "Battle of the Big Bang: The New Tales of Our Cosmic Origins", an overview of the state of modern cosmology on the nature of the big bang. Learn more about your ad choices. Visit megaphone.fm/adchoices

Phil, Naesh, welcome to the show. Thanks, great to be on. Pleasure to be here. What exactly is the Big Bang, Phil? Well, people think they know, but actually there's quite a bit of controversy as to what we even mean by the term Big Bang. So we talk about two definitions, the hot Big Bang, and that's just the idea that the universe evolved from a very hot, dense state. And then after that, it's expanded and expanded, and it caused. and then galaxies formed, and then planets formed, and us.

But there's another definition of the Big Bang, which we might call the Big Bang Singularity. That says that 14 billion years ago, time stopped ticking. This was the beginning of the universe. So that's based off of theorems proven by Penrose and Hawking. And what's interesting is that neither Penrose nor Hawking actually stood buy those theorems. They actually think that some of the assumptions in the theorem don't hold in reality. And so maybe we shouldn't trust the idea that the Big Bang was the beginning.

And in fact, Niayash and I went to a large conference in Copenhagen, and we surveyed physicists. We asked some all sorts of controversies within the field. And in fact, the only one where we got a majority view was that the Big Bang should not be considered the beginning of time. Rather, it's much more modest claim that the universe evolved from a hot-dense state and then expanded afterwards. Interesting. And that hot-dense state that you're referring to is not the same thing as this singularity, right? When people imagine the big bang, almost by definition, it's, well, it's the bang at the beginning. It's where everything got started. And so when you describe this hot-dense state, people might be imagining taking all of the matter and shoving it down to the, you know, the size of an atom.

but this hot, dense state is not that singularity that people imagine. This is sort of a little bit later on in the history of the universe. If there is such a thing as a singularity or whatever, this hot dense state is slightly bigger. The singularity is what would happen if you traced it back using certain assumptions. So we know that it was hotter and denser in the past, hotter and hotter, denser and denser as we trace it back. And if you take certain assumptions, as Penrose and Hawking did, then you get to, this singular state, where the density, well, in some versions, you might say the density goes to infinity. But the point is that the clock stopped ticking, and that's the beginning

of time. But we don't have to assume that. And in fact, lots of cosmologists doubt that. They don't think the Big Bang was necessarily at the beginning. But no one doubts that there was some kind of big bang, and the hot, dense state is what everyone agrees on. But what came before that is the open question. Interesting. The book, by the way, ladies and gentlemen, is Battle of the Big Bang. And the first question, of course, is going to be, what is it exactly that we're, that we're battling over? I think it's a great title for the book. We spoke about this when, when this book was in its sort of formation and one of the working titles was, what banged? And I, you know, this is a better title. Like, this is, this is going to sell more books. Well done for the marketing team. I think

I think that's definitely the pro. But the reason I liked the title, What Banged, was because one of the great sort of questions for people who are scientifically minded, people who are religious, you know, they'll say, oh, yeah, sure, we've got this Big Bang stuff going on. But what we were really interested in is what made it bang, like what actually happened at the beginning. So it seems like when we're talking about the Big Bang, there's this question of this accepted theory of something near the beginning of the universe, maybe, that everyone agrees on the Big Bang. But there's still this great mystery, you know, oh, what exactly was the Big Bang? and what banged it and all of this kind of stuff. Niayesh, what is it about the Big Bang that we can know that isn't part of this mysterious, well, we don't know this,

we don't know which model, what is it about the Big Bang that is this sort of uncontroversially accepted element of, you know, early universe cosmology, and why can we be so confident about this hot, dense version of the Big Bang? That's an excellent question. And before that, I was just looking at your hands. and it says it's this big bang and you say there is one of the common myths about the big bang is it it was a point where things started and big bang is in fact something that happened everywhere so

when you say big bang you shouldn't do this you do like this everywhere is big bang so how do you move your hands to do the big bang everywhere i don't know i've never thought too hard about this this is the big bang i guess it's a big bang dance yeah big bang yeah so it's everywhere and there is a bang. But let's come back to your question. So what do we know about the Big Bang and what don't we know about it? So talking about the Big Bang is kind of like talking about the sun, right? That's kind of uncontroversial.

The sun is hot, right? We feel the heat from the sun. It must be hot. And then we can use a telescope. Of course, hopefully you shouldn't use a regular telescope. You need to put the right filter. Otherwise, you're going to lose your eyes. But you can look at the sun and you could see it shines.

There's a lot of light coming out of it. So based on the properties of the law, you can say that it's a hot surface. But what's inside the sun is a much harder question. And for that, you have to rely on models and a lot of other things. Vibration of the sun, try to figure out what's going on inside of the sun. Big Bang is basically the same thing. We have very good evidence, incontrovertible evidence, that there was something very hot that happened there.

We're looking back. Now, the light we see is not quite the same as the light of the sun. It's colder. is in Microwave. In fact, it was, most people think it was discovered this evidence for the Big Bang, the Kazakh microwave background in 1966

by people in Bell Labs, Pensias and Wilson. We point out that's a little known fact. It was a Canadian where I come from who discovered this Kazakh microwave background 25 years earlier in the 40s.

And yeah, so basically the same way that we see this heat from the sun or we experience or see the light from the sun, there is a heat from the Big Bang that we get to feel. It's cold there because Big Bang happened a long time ago and the universe has expanded since, so it's kind of cooled down that temperature. But nonetheless, we have detected it in various ways now. So there was this hot phase and that's the thing that we know. And we can kind of go and probe the evidence of this hot phase, the same way that we can look at the surface of the sun and look at the spectrum and say that there are these things that

must have been in the sun, we can study the universe and learn about things that could have come out of that hot phase. But then what came before that hot phase, was it a hotter phase, maybe it was a colder phase, those are parts that become kind of more speculative, because we're starting to kind of run out of good theories that could tell us what might be happening. I mean, again, there's analogy with the sun. We've known the sun for millennia since the humans have been around. But what's inside the sun, it's actually pretty recent that we know what's going on,

because for centuries we didn't know why the sun shines. And it wasn't until early 20th century that we discovered nuclear physics. I mean, all the other sorts of energy are just not efficient enough. The sun wouldn't be, would run out of energy within like a few thousand years or a few million years. It wasn't anything we discovered nuclear energy

that we realized basically all stars, including our sun, are nuclear reactions. And that was a missing bit of physics that kind of had bewildered physicists or astronomers for centuries. And when we found that missing piece of physics, then we could actually model the stars and the sun in particular. For the Big Bang, we still have that missing piece of physics. And this is kind of the theme across our book that the problem is gravity and quantum mechanics both become very strong as we approach the Big Bang. and we don't really have a unifying theory of quantum gravity.

There are many proposals for this, but since we don't really have that theory, we cannot really come up with a good unified story, the same way that we have for the sun. So the same way that we are waiting, basic nuclear physics, eventually solve the mystery of what happened to the core of the sun. That hasn't happened for the Big Bang yet,

but that's where we're going and that's what we're trying to do. So we've got some good evidence for this hot, dense, state of the universe. And you've just mentioned this cosmic microwave background radiation, which many listeners might have heard of. And there's that wonderful story of Penzias and Wilson who are sort of, I can't remember what it was they were actually doing when they kept getting this hissing. They were working at a, it was like a telecommunications. Yeah, they were working for Bell Labs. So yeah, they were a telecommunications company. In fact, there's an incredible irony here because one idea for what might have come before the Big Bang is something called

the big bounce. So there was a contracting universe and an expanding universe. And in fact, what was happening at Bell Labs early in the early 60s was they were testing communication satellites. And there was a documentary made about what they were doing. And the name of the documentary was called the Big Bounce because they were bouncing signals of satellites. That's so funny. I love the, you know, the way that these like myths and stories crop up in the history of cosmology. Not all of which are true, by the way. Like I have been telling people on this podcast for years that the term Big Bang was made up by Fred Hoyle to make fun of people who believed in this ridiculous big. But there's this idea that Fred Hoyle, who's one of the sort of opponents of this beginning of the universe view, is on a radio station and he goes, you know, these guys believing in their big bang and that's where the word comes from. Fred Hoyle did come up with the term, but it wasn't pejorative, right? No, there's no evidence that it was pejorative. People assume it was pejorative. Maybe because he was an opponent of the Big Bang, but what they forget is that he was also one of the main popularizers of science at the time,

and he was trying to explain the rival theories to his audience in a way that could give some sort of metaphor because he was on the radios, no visual aids. And in fact, Gamoff, who was one of the proponents of the Big Bang, told his students that that Hoyle had used it pejoratively in a debate that they did on the BBC radio. but a historian of cosmology Helga Krog showed that there never was such a right, it made it up, it just didn't happen. So that's where the myth of the majority of term comes from, but there's just no evidence. It's a shame, it's such a good story as well though, isn't it? It's always fun when people take on these labels. Another myth, well, I say a myth, another myth that you sort of hinted at just then,

Nehash, is the idea that Penzius and Wilson sort of geniusly discover this sought-after microwave background radiation. This is like, they call it the afterglow, of the Big Bang. Right. The Big Bang happens and it leaves this pattern of heat all across the universe, which if the Big Bang occurred, we should still be able to detect today. Yeah, that's right.

And so there were sort of people looking for it. And then Penzias and Wilson, geniuses as they are, discover it finally, prove the Big Bang and win the Nobel Prize. It is true that they got the Nobel Prize, but they discovered it by accident. That's right. Just up the road from people who were working on trying to find it and were nearly there. And even though they found it by accident, they're the ones who got the Nobel Prize. had been detected earlier, just not recognized.

That's right. It's this incredible story of how all the evidence was sort of there, but it just took the right people to put it together. There's so much historical contingency involved in actually finding the right evidence in the right context. And it's amazing how these kind of discoveries happen because often there are like so many pieces of evidence that are here and there and pop up. And in the hindsight, you go back and say, oh, we could have inferred this from this and

from that. But anytime, and I mean, it happens over and over in the history of science, that when you're leading up to, like, a big discovery, there are all these bits and pieces that are there, but just people don't see it, and it just maybe takes a bit of luck. And in this case, Penzias and Wilson called up Bob Dickie, Princeton, who was a professor, and was looking for this, basically, for years. And he said, okay, we see this hissing thing, and then basically he says, oh, yeah, yeah, this is what we're looking for. That wasn't their intention. But it's amazing. And it kind of, it tells, I think it's kind of, there's a broader lesson here, which is about the role of serendipity in discovery that, so Bell Labs, for example,

it's, I mean, it's a commercial company, right? They were trying to make communication and phones. But this Bell Labs was actually amazing. They did a lot of research, very fundamental research. And nowadays, it doesn't happen very often. Like, companies want to make money and they don't really focus on fundamental science or just research and development as much. And it's all kind of reversed with the government and we know what happens with the government's government's kind of their budget cost and stuff. But yeah, the question is you do need this investment in serendipist science because you never know where these things are going to come from. And these connections are random. But if there are enough of these triggers, eventually they're going to

connect. And I mean, that's what happened for the CNB, that there were people were anticipating something and and then there was enough investment in direction of kind of advancing technology to find it and then it eventually happened and I mean I'm amazed at what's going to be in the next discovery might be already in the making there might be pieces that are here and there people are seeing things they cannot quite connect the dots but if there are enough of them hopefully that those connections will happen again but of course the first evidence for the big bang we've had for thousands and thousands of years since the writing of Genesis of course, which predicted that the universe began to exist out of nothing, that God said, let there be light, ladies and gentlemen, and now we have this evidence that exactly that has occurred.

In fact, it was a Catholic priest who is credited with sort of first maybe coming up with this idea of the Big Bang. I never like to pronounce this name, but it's something like George Lamat. It's Lemaître. Lemaître, with a bit of a phlegm in there somewhere. And he's a Catholic priest. and when he sort of theorises this big bang and when the evidence starts coming in, Pope Pius, the Pope of the Catholic Church, declares publicly that this is the evidence of the Fiat Lux, of the let there be light.

So quite clearly, at the very least, we've got evidence pointing toward, even if it's just this sort of, you know, at that time, just the cosmic background radiation later on and the universe's expansion and stuff, we're looking at evidence for the beginning of the universe, right? Well, it's interesting to talk about Lometra because he was a very jovial chap, apparently, always in a good mood, except for that moment when the Pope declared the Fiat Lux and said we're going to use the Big Bang to prove Genesis. Lometra was very, very unhappy about that.

He wanted to keep his science and his religion absolutely separate. And he had a meeting with the Pope. Now, no one knows what was said at this meeting, but the rumor is that he told the Pope do not use the Big Bang as evidence of Genesis. This is a very bad idea. And his subsequent talks, Pope Pius never mentioned the Big Bang again. So I think it's good advice from Lemaître not to use it. And actually, I was brought up Hebrew. So I actually know the Hebrew. And I don't think it's even been translated properly. I don't think it says in the beginning, God created the heavens and the earth. What I think it says is, and a lot of people with scholars agree with me,

is that when God began to create the land and the sky, and we know it's land and sky, because the words in Hebrew, Ha Aris means the land. I mean, lots of Jewish children will sing songs about the land of Israel, Ha Erex Israel. And Hashemayam is the sky. It's where the birds fly. So I I don't think Genesis is in any way talking about the beginning of the universe as we know it. In fact, a lot of rabbis thought there was something before the creation. There was a chaotic state. And so when God moves over the face of the waters, this is a representation of the primordial chaos. And it's very, very similar to the Babylonian myth, the Anuma Elish.

And lots of people have drawn parallels to the Anuma Elish. So much more likely what's going on in Genesis is a sort of, monotheistic repackaging of this ancient Babylonian myth. And indeed, in the Babylonian myth, there are sort of seven tablets of creation, the gods rest at the end, they defeat the sea monster called Tiamat, and the face of the deep, the word deep in Hebrew, is something very, very similar to Tiamat. So I don't think there's any real description of the Big Bang in Genesis. And it doesn't really say that the universe had a beginning.

It doesn't talk about a beginning of time. It doesn't say the universe came from nothing. And ironically, neither does the Big Bang say the universe came from nothing. It just says it came from a hot, dense state. So not only does the Big Bang not describe the universe from nothing, but neither does Genesis. It's a great irony, isn't it? I mean, I did an episode a while back on the translation of this particular passage in Genesis. In the beginning, God creates the heavens and the earth, or when God created the heavens

and the earth or the land in the sky, he did this. And it's the difference between there sort of being this empty frame at the beginning of the cartoon. This, I had this guy called Magnify on my channel. And he sort of imagined it like a cartoon strip. In one interpretation, the first sort of square is like an empty box. That's the beginning. And then God creates. Whereas on this other interpretation, in that very first cartoon box, you've got God, you've got the primordial matter.

And God sort of fashions it. And this is a great irony, isn't it? Because, like, you know, people think that Genesis says that there's a beginning of the universe and the Big Bang proved it. But actually, translation-wise, maybe it doesn't. And actually, if we're careful enough, maybe the Big Bang doesn't either. So when people hear the Big Bang, they're going to think we're talking about the beginning of the universe. That's what the Big Bang, like, is by definition, right? We've just talked about these two different definitions. Yeah, yeah, yeah. Why is the Big Bang maybe not the beginning of the universe? I

thought that's kind of what the whole thing was about. Right. So, of course, that, like many questions, that depends on what you mean by the beginning. So the Biggie Bang, in some sense, is the beginning of something. It is the beginning of where we start to understand how to describe universe, to talk about the universe in the language that we can speak right now. So we have this hot dance estate and then we can go back. And then at some point, kind of things become less and less clear, basically more and more fuzzy. So, I mean, the earliest we can use the laws of physics and we have direct ways of kind of testing

what we say about the Big Bang is maybe a minute or so after the so-called initial singularity. 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. primarily at the Big Bank. And going before that, we have ideas.

But then we kind of go in a limb. We kind of take 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, and maybe it's going to go that way for an hour, maybe it's going

to stop in one minute and take a turn. You don't really know because you can, 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 a stop at some point. This is like a backwards extrapolation. Yeah, exactly, backwards.

Like shrinking the universe down and down. That's right. Assuming that that keeps going, right. Assuming that it keeps going, right. Assuming that it keeps us to this point where kind of time stops ticking and densities and pressures could kind of, and temperatures could blow up, basically go to infinity. So that is what Penrose and Harking back in the 60s called singularities and it thought it was unavoidable according to those theorems. But those are based in assumptions and we know that the assumptions fail and everybody, almost every practicing physicist thinks at least one of the assumptions that little singularities fail at some

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the center of a black hole famously. That's right. That's right. It's Kenrose's work on singularities in a black hole 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 reverse. 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? Excellent, excellent. So there are basically four theorems, sorry, four assumptions that go in these singularity theorems, and these are 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 the universe is speeding up. So right now, this very minute we're talking, on very large scales, gravity is not attractive, is repulsive. So, of course, back in the 60s, they didn't know that. So they assume gravity was attractive.

That's assumption number one. Assumption number two is we have three dimensions of a 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 of 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. Or maybe you could get rid of one space and add one time or vice versa. Maybe you can know time and four spaces, etc. 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 fiction, could there be time machines? 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. And assumption number four, which at some level at the heart of basically any theorem, is that you need to assume some mathematics, basically. And the mathematics was mathematics of Einstein's theory of general relativity. But that one, that also we know it 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 basically technology for us to be able to communicate. So rules of quantum mechanics are very, very successful

that happen to be inconsistent with mathematics of general physics. relativity. So that needs to be revised as well. So these four assumptions, probably at least one of them, maybe all of them, 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 in 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, Kazakh microwave background, distribution of galaxies, the geometry of the Big Bang, the sound waves that we measure coming out of the Big Bang. So these are all the things that whatever imaginative, creative thing you come up with has to explain. And this is no joke, ladies and gentlemen. 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. 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. And that's why I love this so much, because it's, it's one of those, it's one of those books that it doesn't profess to have an answer. So you just have to sort of go away and, and give it some thought. And one of the big questions is that throughout all of these different models, and you talk about some, you know,

25 or so different models of what the Big Bang actually was and how it worked is you actually got like a cheat sheet at the end, a big table of like, you know, does it involve inflation? Does it, yeah. And one of the columns in this table is, does this model say the universe has a beginning? And the majority of them say no. That's right. So, hold on, like, if the Big Bang is not the beginning of the universe, and if you've got this whole table, which says, here are like 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? 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. Is that because the Big Bang is so, small? Or like, why is it that general relativity breaks down at the Big Bang? So I wouldn't necessarily say the university is smaller 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 that's smaller. So what 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. But what's Does it mean to say that it might not have actually been small? 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. Uh-huh. Yeah.

That's what you can see at the moment. I can't see what's outside this room. Yeah. So similarly, we can see out quite far. But nobody thinks the distances that we can see billions of light is. 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 I think it's even mathematically reasonable, actually. So we know about black holes, your hair about black holes. Like black holes have these horizons, right? If you fall into them, you cannot get that. Event horizon.

The point at which not even light can escape. Not even light can escape, right? So if you're outside, in principle, you can shine a light. but if you fall inside of it, even if a shine, flash, it cannot get out, right? Universe is actually, even today, the universe is like a black hole inside out.

So we have a horizon, but instead of we 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, yeah, we are in the center and the horizon surrounds around us is everywhere. Whoa. Okay. And is that to do with the expansion of the universe? It has to do. Exactly.

Exactly. So the expansion of a universe is actually stretching everyone, is pulling everyone apart. And at some point, there is a point that we are being pulled apart in something as fast than a speed of light, which you think, like, fast, it should be impossible. but this is the thing. I cannot move faster than a speed of light relative to you, but the universe somehow can't move fast in the speed of light. It's something as in fact within the mathematics of relativity itself.

You're not really violating anything because there's no particle that's moving fast than a speed of light, is the space itself is 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. So 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 as smaller and as smaller as they get closer and closer to the Big Bang. So a universe, so the space could be infinitely big. We don't know, but, I mean, it's consistent with observation that space is infinitely big. But the amount of a space that we can see up to the horizon, basically, the cosmological horizon, become as smaller and as small as you get. to the big back.

Yeah, as if we had like 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, 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 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? 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, because I know how much you hate raisins, Phil. Expanding, 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 ship, it can't reach you. That's right. Because the whole thing is moving away faster than the speed of light. Absolutely. It's kind of like, you know, a car driving away faster than the speed of sound. If you play a sound, that sounds 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 omitting 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 student, a relativity, I say, you shouldn't compare sound and lights in that extent. Because in fact, sound always travels with its medium, right? Oh, sure. 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, whereas light just... Light is independent of a frame, right? So I think it would be true that if there's a sound and then moving like you have a supersonic plane, then you may not hear basically because it's moving very fast and speed of sound.

But if the supersonic plane make a sound, we're going to hear it. Because the sound is propagating with respect to... Sure. Yeah, yeah. And it's helpful to visualize. I mean, I guess if people are struggling to imagine this. Imagine, 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

five 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 like 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. Because the overall movement is away, that particle goes away. 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 like 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 Big Bang being like, by definition, beyond our observational capacities, how can you 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. Good. You were asking, what is this book actually? I just had an idea. You heard about the Schrodinger's cat.

There's like a dead cat and a live 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 get to what's fiction, what myth

about the Big Bank? And there's a lot of myths about the Big Bank. There are some that we talked about but there's also myths that kind of cosmologists believe in and they think is supported by evidence or they think is proven. For example, there is a leading theory of the Big Bank 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. This is right near the beginning. Right near the beginning.

And this is, so this is an idea. Now, I'm going to tell. As you explain that, what's the difference between, you know, the Big Bang theory as a whole is a big expansion of the beginning of the universe? So what's inflation as succinct from just the Big Bang expansion? 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. 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. And inflation is the idea that there is this like exponential speeding up kind of growth rather than just a sort of linear growth. Yeah, exactly. So this repulsive gravity, the idea is that there was repulsive gravity much, much as stronger than it is today back then, before there was this hot, dense state of the Big Bang. and that's kind of a stretch to the universe by 30 years of magnitude, basically there are 100 doublings or so, basic universe doubled in size in a tiny, tiny fraction of a second, many, many times. And because the reason it could do it was gravity, it was repulsive and very, very repulsive.

And what it does is that it kind of tends, it takes a tiny speck where you could have tiny quantum fluctuations in it, and it stretches it across the universe. 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 the sun waves that we see that basically form,

we see the ripples in the cosmic market of a 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 named like Roger Pendos, who actually one of the originators of singularity theorems and won a Nobel Prize for them a few years ago, he thinks

that inflation is not really a reasonable theory. And maybe 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 see, we 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 park 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. But I think, in a inadvertently, he maybe gave a very good name to this theory we talk about, because bang, when you think about bang, is 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 Kazakh-Marcova background that were just the sunwaves, 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're very, very, very, much bigger than much longer wavelength than the sound was used to communicate right now. But they are there, and they're measured very precisely, and any speculative weird time travel idea you come up with has to explain them, right? And that's kind of, that's why... 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, universe... Leading change can feel impossible when nothing's quite working, and you are drowning in competing priorities. I'm Michael Bangay-San, a host of Change Signal. It's the podcast that cuts through the noise. to give you clarity and confidence. If you want to be a masterful change leader,

change signal will be your favorite podcast. You'll find it on your favorite app. This 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? You need air for sound to travel.

Very good, good, good, yeah, 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 has very high density. So soundvests could propagate in it. Primordial plasma. 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. I told you, the 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 it's like a star inside, like a sun inside. 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 is this thing called the last scattering surface, which is kind of the surface of the Big Bang, where the density is low enough so light can propagate to us.

But then beyond that, light cannot propagate directly, but sun 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 sunquakes. It's called, like, Helios seismology is a sign. So because sun is kind of very active, you could, if there are solar flares, in fact, Phil is very good. And imaging all sorts of sun-related things and auroras and then the pictures of the various. And Phil's own images appear in the middle of the book.

And I must put a link to your, like, what is it, your Flickr account or whatever? Phil is also a phenomenally talented, like, space photographer. It's like I was blown away the first time I saw it. So I'll try to remember for that in the description as well. So, yeah, but the sun. The sun, yes. The sun is a very active place, and there are all various activity that happens. 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 sand waves and also there are gravity waves, there are different types of waves. By mapping these sun as 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, I mean, Earth, there are also earthquakes, and we're mapping those. So we're looking at the effect 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. And that's what we do with the Big Bang. We see the surface of the Big Bang. It's obviously inside instead of hard size. 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.

That's interesting, yeah. Yeah. But it's the same kind of. It's the same idea. And those soundways 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 science. So neutrinos are this weakly couple particles that are made at the big, at the fusion in the center of the sun. And we eventually detected them. We've been detecting it for a few decades, but they weren't quite matching until we detected all different types of neutrinos. So the key is that you want something that can freely propagate in the space.

For the Big Bang, there are neutrinos. It's just very hard to see, so we haven't quite cracked that, not 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 that you could have geometry of a space, according to ancestor of relativity, which could wrap ripple and wave. And those could have been emitted from the Big Bang. And there are many theories, some of the theories of the Big Bang predicted these waves are

there as well. 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 fixing. There is some non-fixing it is well. 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, OK, I thought we knew that already. You know, the Big Bang, the universe expands. You might say, no, inflation says that it's speed.

up. I thought we kind of knew that already anyway. You know, everyone knows the universe is expanding and kind of who cares? Like, okay, it's faster. What's the importance of this inflation idea? 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 Bank. So if we can confirm inflation is true, then we can tell what happened before the Big Bang. What does that mean? So what is it that's inflating?

Okay, so it's the space that's inflating. And so this is before the hot dense state. Yeah, it's before the hot dense state. So what are we talking about here? Like, help us to visualize this. Well, imagine empty space, but it's filled with some, 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 the big bang is what happens after inflation,

whereas a lot of textbooks will tell you it's big bang then inflation. But even I interviewed Alan Goose, the inventor of inflation, and he calls it a prequel to the big bank. So inflation, big like 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. Yeah, because it's supposed to be unstable.

So it decays. And this is the next most important implication. But then energy, the energy of that expanding space turns into matter and radiation, and that matter and radiation is the bank. Is the bank. Yes, absolutely. 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 exponential expansion. 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 has a decayed, it keeps expanding. So you get another big bang. So analogy I use is Sunday afternoon when I go to my mum's house and she makes this fantastic chocolate cake.

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 we had before and we could just keep going forever in this analogy what is what is the cake what is the thing that's getting bigger and bigger it's the space the inflating space and our universe is not that inflating space

no it's what came when that inflating space space decayed into matter and radiation. But so I'm, and help me picture this, right? So we've got inflating spaces. This is inflation. You've got space sort of getting bigger. Yeah. And then inflation stops.

In our patch. But so what, so, so, so you've got this sort of big inflating space. Yeah. And it's just a little patch of that inflating space that stops inflating. Yes. Which causes this boom, like energy matter, all this kind of stuff. Yeah. Yeah.

But the whole thing is still expanding. And so that little miniature part is, 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. Yeah. And so there are little patches where it stops and that's womb, boom, boom, boom, boom, big bang, big bang, big bang, maybe little bang. Yeah. That's what most inflationary cosmologists suggest. Okay. So does that mean that this inflationary idea points to a multiverse? Yes. Is that all we're talking about? 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. I'm often told that the only reason people believe in the multiverse is as a way to get out of like the fine-tuning argument for the existence of God. In other words, like the multiverse, like, 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. I mean, it was, it was A discovery, it wasn't, it wasn't, 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 Neai Esch'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.

Then another scientist came along with Alex Valenkin and Andre Linde as well. And they showed that this was a generic property of inflation. So Alan Gooth, there are actually lots of different inflation models. But what Goose says, he's the creative 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 Mukunov's one, that don't agree

with this. 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 can say, you know, inflation made lots of predictions, but then you can challenge that and say, well, maybe that's a dubious statement. So, I mean, I think Nyash 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 strongly supported and others times I'm with it. I think Phil has to be very diplomatic, because he interviews old people. So, again, I can be more strongly worded. But in the book, we try to find a common voice so that nobody gets offended. Sure. To be clear, Alan Goose 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. But we do talk about whether it's possible to make a universe in a lab. That's the other thing, right? And Alan Goose is one of the scientists who suggested that it might actually be possible. Okay, look, I want to talk about that. Yeah. But also, I want to just, I want to take a moment because, like, you guys have been writing about this for, it must have been years now, like 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 it's in the description if people want sort of a documentary version, I suppose, at this book. 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 a local patches of, you know, creations of like mini universes everywhere. There are going to be a few questions that come to mind. 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, like, inflation stopping because it's unstable. I'm 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 warm, like matter and energy, just, like, what, out of nothing, out of nowhere? Like, you know what I mean? Can we take a step back? Now that people understand what we're talking about,

this big sort of 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? Like, where are we, where's this coming from? You know what I mean? So imagine like a pool table.

Okay. But imagine like there's a hole in the middle somewhere. And so imagine there no friction. Okay, sorry. I should not imagine too much. Okay, so imagine or no fix it. So they're like kind of, imagine you can hit the pool, a ball and it just keeps bumping left and right and is all over the place, right?

So that's kind of like a quantum C or if you want. So that's the pool table is inflation. It's 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. But the thing is that this ball does different, I mean, the state of the space, doing different things in different places.

They don't talk to, which is in 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 hits up, right? So, 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. 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 inflation. it's just that a much heavier empty space. The vacuum energy during inflation would have been much higher because we're much faster expansion,

much faster repulsion, or 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. There's a lot of fluctuation. that are happening, things are moving around. So, I mean, the ball, in the pool, I'm moving around, this is like a classical thing. But really, I mean, all the fields in a space

are vibrating, like, very violently in quantum mechanics, basically. So this empty space is this sort of ocean of quantum fluctuation? That's right, exactly. And that's everywhere, right? But the thing is, the instability, the idea of instability, is that it could be, and it doesn't have to be, But, I mean, for big bank 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 and physics. So if your fields come across this hole, then they may fall into it, and that's where kind of the heat up, and then you create matter and radiation and stuff. 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. Some places that happen, those places you 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 kind of we need fluctuations to actually grow.

We cannot live in vacuum. 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, yeah. And some of these fluctuations sort of pop matter and energy into into 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 like 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. 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 Niyash 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. Maybe inflation is past eternal as well.

But surely if we're going, if we're thinking about going backwards in time, if something is shrinking. But remember, the whole universe could be infinitely big, right? So when we said shrinking or it's only a particular patch that we're concerned or, you know, are the equivalent of us in this room or what we can see. 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 like there is, that is just what's going on. The majority, in this scenario, the majority of the universe is inflating. And that never end. 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. Is it past eternal? And little universe

Yeah, so people often quote a theorem by Bordeaux, Guethe, and Valen. Yeah. And that says that inflation cannot be past eternal. However, other scientists have said, actually, it can be past eternal, that 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 if 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. And unfortunately, theorists don't agree about this. So we don't know whether inflation would be past eternal or not. Hey, let's talk about your expense report. I didn't submit an expense report.

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So then you could ask, okay, well, what happened before inflation? And what would that question look like? Because now we're not looking at this hot, dense, big bang, matter, and energy. We're talking about the beginning. 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. Like, I don't know, my like, is there time in this, 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? Yeah, like, I'm struggling to like visualize it. I'm visualizing almost this like fabric expanding. a bunch of lines going through space that's growing and growing and growing. And it's full of quantum fluctuations. Does time pass in this inflationary universe, for example? Okay. No, no.

It sounds that there isn't, 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 a space, there's energy, everything kind of works in the way 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 less the conflicting relationship with the quantum mechanics quote Einstein saying god doesn't play dice with the universe I only found out from your book that Niels Bohr you know responds by saying Einstein stop telling god what to do right that's true

yep yep indeed so but these are all like 100 year old ideas you 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, 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 predict, give you a vacuum energy.

Now, may not give you the right amount of vacuum energy, but can give you a vacuum energy? 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 the term of 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 I'm familiar 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 Hawking proposed that maybe inflation was not eternal. 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 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 Anagia liked that Phil uses is like the wetness of water, right? 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 look at it with a very powerful

Microsoft, it's just made out of molecules, right? There is no fundamental concept of it. 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. 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. Right, right. 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? What could mean, say the beginning? Well, I mean, you could be tried to be precise about it. And I mean, you can 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. And in 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 their sleep, this exact point is where someone falls asleep. 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. 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 there's a point, if we go back and back and back, there's a point of which, you know, 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 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 time, timeless, then the universe has to timelessly not exist. How do you get this beginning of time at a point in time? You get what I'm saying? Well, one definition of time, I don't know if everyone,

I don't know if the United Nations 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.

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 Cresci-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 we're sort of somehow privileging a particular moment, 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. 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. Yeah. If people are struggling to imagine, like, you know, they're sort of thinking, well, how can there be a beginning of time? 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 a really difficult challenge to be thinking about the beginning

of time, but maybe that should's 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. There could be, yeah, we can't help but use this word before, right? Yeah, yeah, yeah, yeah. Because it's part of our lexicon, and we're used to the familiar world of our experience. Sure. 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. 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 to 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 NIAES has 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's has a cyclic universe that loses its sense of scale 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. And I don't mean a clock like, you know, 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. Here's a problem, Phil. As you well know, right, if we're imagining this eternal inflation, you know, so time sort of stretches back infinitely. We've got our little pocket universe, but everything else just sort of goes back infinitely and there's no beginning.

As you well know from the study of the philosophy of religion, this is not possible, right? 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 okay, 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, you know, 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, 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. I've actually made a documentary on this Calam 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 naught 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, 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 are used 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. 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. You understand the grammar of the problem, right? Which is that, okay, so there's no point of 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 chain. How should we be thinking about it? Because the only other way I can think about it is like me right now.

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. So there's no beginning to the past and there's no end to the future short. 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 past. 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 and to, because there's just no starting point. It's just like impossible to wrap our heads around. Why would you say it's your privilege if everyone else is 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. Yeah. But also just like metaphysically, right? Like I mean like 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. 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 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, 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. Well, 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 round, or whether it didn't have a beginning. That's also hard to get a head right. And 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.

Now, could the universe be eternal into the past? There's no contradiction with that. Now, some people will say there's actually a contradiction, you know, William Lane Crone. Yeah, like the Hilbert's Hotel. Anytime you introduce the concept of infinity, it leads to paradoxes. 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. Hey, Richard, great to speak to you.

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who used Hilbert's Hotel and popularized it, because I think Hilbert mentioned it once in a lecture, and that was it. Yeah, interesting. And what Gamov was trying to say, well, 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. So, in fact, the universe, and he was trying to say, look, the universe could be infinite and expand.

So Hilbert's Hotel is the idea of this hotel with an infinite number of rooms, right? It's 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. so we say, okay, we've got a, we 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, um, what is it? He says, like, like no vacancy guests welcome, you know, 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. Yeah, that's exactly why it was popular. Hey, cool. I mean, Hilbert didn't think about this, but as I say, I think my understanding is he gave one lecture about it. Yeah.

Never mentioned it's so often like, 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 than Ayesh, 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 Trotinger 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 is like

proved that the cat is dead and alive at the same time. It's like 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. And let's just go to... That still expands. Yeah, that's still expands. Yeah, so let's just go to the sort of notion that it leads to a paradox or a contradiction.

Yeah, sure. Okay. 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 Hillbert Hotel can be full. But if what you mean by full is can't admit new guests, then the Hillbett Hotel cannot be full. It can never be full. So the Hillbott 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. Yeah, because from that you can derive that one equals two. 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, like, 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? It was, yeah. Right. Okay.

So if I said there, 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, right? 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 the same. You can't just say infinity.

Exactly. 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. what how many glasses of water are we left with one okay right let's go again now i'm gonna 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 this has given us two glasses of water yeah because it depends what you take away 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 like set of infinite things particular kind of infinity, right? 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. Okay. Nehash, 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? Yeah, I mean, infinity is all over mathematics, right? So it's, I mean, all this stuff, I mean, kind of 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 built physical. using mathematical language. So same places that there's infinity in matters, infinity in physics, because there's just the same thing. Right. But then the question is, yeah, so where are the places in physics where infinity cannot be?

And if I'm measuring something, like I'm measuring the time or temperature in this room or anything I measure, 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 lumber. 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, 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, infinite mini-pockets with various properties I don't have access to.

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. There's no testable prediction. And of course, 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. But, I mean, for the most part, it's either untestable or very hard to test.

Infinite time is kind of the same, right, at this in my view, because if there are things that happen a very long time ago, like long before the hot pig bank that we see, I mean, whether they're there, where they're 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 the skepticism, a turn-in-face and a multiverse. So my own favorite, I think we talked about Hartel Hawking model where time begins to exist at some point, didn't exist before some time. We work on a different model called holographic cosmology, with Costas Scandaris 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. So there is this idea of holography that really understanding gravity is like understanding quantum mechanics in one lower dimensions, 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 a space or one dimension of time.

It's kind of an illusion. Okay. Yeah. Pause. 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.

beach or whatever. It's a 2D plane, but it kind of looks 3D. You look at it angles and it shifts and it moves. It is actually 2D. It's actually 2D. But it has the appearance of three dimensions. Right. You sort of move around it. Yeah. 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. 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. is a holograph. That's right.

They're forced like an illusion? This is a good question. So now, illusion is a kind of depends on your definition of reality, right? Yeah. 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. Okay, so you may think it's an illusion, but it's a very good illusion.

It's a very, very convincing illusion, right? 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, right? It's possible, right? But it's just not very convincing illusion, right? And the idea, this modern idea of holograph 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's that we're familiar with.

But that depends on the situation. And we know that our 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 a vacuum. You have very strong curvature. 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 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 a 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, so past the Hot Big Bang, maybe close to Big Bang singularity,

this is where this three plus one dimensional description wrecks on and maybe you just have three dimensions of space. No dimension of time. No dimension of time. Just dimensions of time. 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. Is this a version of time being like an emergent property? That's the idea. So if this case, time would be emergent. 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 like 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. 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. You know, a cake is spongy. But if you zoom in and look at all of the atoms that's made of, none of the atoms are spongy. You have to zoom out. And it's not like

when you start zooming in with a microscope to this cake, sponginess just disappears. You're operating on a level where it just hasn't emerged yet. 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 is an excellent analogy. In fact, there is a, if you have a technical word for exactly 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 renormalization. I think we don't have a video about everything. That's right. Yeah. Is this how, like, I mean, one phrase that we often hear, especially in like 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 sort of 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 like outside of scientific apparatus if science relies on laws to sort of explain the universe and these laws break down at the Big Bang? 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 before.

Yeah, of course. Do you think it makes sense? I think the case is that it's general relativity. breaks down at the big bank. Interesting. So it's not necessarily the laws of physics break down, but rather the laws that we have break down.

And what people like Neaiash 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 that new laws came into existence, as you pointed out, Alan Goose didn't invent the inflation, invented the theory.

So this is what a physicist 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, you know, that in his no boundary proposal, the laws of physics would hold everywhere. 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 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 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. And for Lincoln says that he just thinks that the laws of physics just exist like as a platonic object. They're just these things that just definitely not my view of the laws of physics, but it does lead to this interesting question. question of like, it does seem like there needs to be something exterior at all of this, right? Like, 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. Like, 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. 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, you know, there is a big bang singularity or something, if it did begin to exist out of nothing, do you think it needs a cause? Personally, my opinion is no. We certainly can't demand that it must have a cause. Okay.

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so one you mentioned was was coming from a quantum fluctuation of the vacuum. And that's, it's an older idea of the universe from nothing that goes back to Edward Tryon. And when people sort of make criticisms of the idea of the universe from nothing, they say, That's not nothing. That's not nothing, because that's a vacuum. And Neo-Eyesh talked about the vacuum is not nothing. Vacuums can't be nothing.

It's got all kinds of activity in it. But what Valenkins 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. So it's not coming from a vacuum. So what's it coming from? 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, like, as Aristotle said, what rocks dreamers.

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, as 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 Valenkin's model, there is no space. The way you can think of it, you know, you've been involved in philosophy of religion, Alex, and you'll be familiar with the idea that God created the universe ex neilo, no material, no material that we know of. No materials.

So that's what we're talking about here. It's exactly analogous. The universe has created ex-neilo, nothing material that we know of. You know, nothing like anything you can see in this room, not even a vacuum, 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, you know, a deer has just spontaneously begun to exist in your kitchen and is currently destroying it.

Shouldn't you go and check? Well, I asked for Lincoln this. I sat in his office and I asked him, I said, why can't 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. Yeah, that is true. Right. But it's just unimaginably unlikely, so no need to worry about it.

But that wouldn't be out of nothing, right? That would be out of the quantum. 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. You know, there's no space, there's no nothing. It just, just a tiger just appears. Why aren't you worried that that's going to happen right now? Well, we're not in nothing.

So if it can come out of nothing, well, that's not where we are. You know, we're in this universe, so it has to play by the rules of this universe. Now, the question is, you know, could a tiger appear out of nothing, like empty, not empty space, sorry, just no space. Right. Well, what Valenkin tried to do was to use inflation, say, look, the probability of a universe coming out of nothing and actually lasting is incredibly small. But what he suggested, 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. Sure.

So now let's go on to this issue of causality. Yeah. Right. 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? Right. And what's often, the reply is often, well, God doesn't need a cause because God doesn't have a beginning.

It doesn't necessarily exists. God doesn't have a beginning. Only things that have a beginnings need causes. Yeah, that's that have a calam. Okay, yeah, so that's in the calam 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. But now let's go back to Nea Aeotaphic 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 a causes because we don't know if causality is fundamental. Yeah, this is kind of like a version of when people say, well, you know, 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 which sort of, you know, from which everything else stems. 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, Naeush, 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 sort of theist day on. I say, okay, so we've got this timeless cause, but we've got a temporal effect. 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

Here's the problem right If you've got a timeless Cause It just exists Timelessly forever There's no like beginning to it It just exists You used to set forever

So that doesn't mean timeless Exist Outside of time There's no point in time At which it doesn't exist Let's say that Right 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. It needs to have, in other words, as theus 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 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 course doesn't exist, the course 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? 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 missus stated it.

So I guess it's timeless in the sense that in this early estate, 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? 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 this 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. Okay. There is one description with time, and there's another description without time. and they're equivalent description. 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 timeless one is the cause, and timeful one is the, the effect, then they're in fact the same things.

So we are the God. Is that right? Well, you know, I really thought we'd get to the end of this without any kind of blasphemy. We'd 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 implore people to go and buy it because, I mean, Carla Rovelli on the front cover describes this as an intellectual feast, and I think he is, 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. 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. And, like, if, you know, 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? 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. It's not impossible. Valen 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. 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 avoid God. But what he didn't know is that Richard Gott, who came up with this model, was actually a believer. So the question might still be, well, why does the universe exist? And, you know, 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, 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, you know, why does the universe exist? I mean, you can try and make inferences about it. Like if we look at the Valen-Tunneling from Nothing model, you could say the universe exists because the laws of physics exist. 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, you know, I think Bertrand Russell just said the universe just is and that's it. 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. So Joe Rogan might have the wrong idea of what the Big Bang is and what what you're required to believe to accept the Big Bang, but it's not illegitimate of him to go, but 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? I don't know if I'd want to use

the word miracle. There are certainly unanswered questions that I think physics, you know, it's not setting its task to answer. Do you think Joe Rogan is embodying and like an illegitimate, like 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, that's more sensible to me. Well, we ask you to embrace the uncertainty. And sticking with Jesus is not embracing the uncertainty. So you're not asking someone like Joe Rogan to say, don't stick with Jesus. stick with, you know, 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. Naesh, do you have a view on this? Yeah, I mean, I think this is just a misunderstanding of kind of scientific methods saying that we asked. Miracle, of course, is a loaded word, depends on, I guess, if you're religious or not.

Depends, you feel differently about it. But anything you asked this earlier, that, okay, does the rules break, do the rules break at the Big Bang? And I was going to say, and I can kind of say that again, like 150 years ago, the rule, rules of physics broke at the surface of the sun. So, yeah. Was that God there? Yeah, and 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. That's right, absolutely. I mean, 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. And 150 years ago, that was the surface. of the sun. And then we learn about relativity, learn 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 bank singularity or a hot big bank. Are we making progress? I think we are making progress. I think we're pushing further. But, I mean, it's kind of an arbitrary point to say that, okay, so now this is where this 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 varies. But it hasn't. It's been making progress, 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 question. 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 thousands of years, if not longer, as far as we know in written history. So the question, and this is the question I'd 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 with our ancestors have been living. And I mean, okay, on the surface is very different, but we're 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. And we kind of kind of, go into lengths, to what extent that question even meaningful, right? That maybe in some sense there are similarities, but then also the differences, 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 it's, but I think this is,

that's one thing, that I think religion, as much as we may want to distance us from, distant 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. Like, I mean, religion has been used to build communities

for thousands of years and we built communities among scientists are we using similar practices yeah science is not immune from dogma this is the point and in fact we were just talking before we shot about how in is it chapter 10 of the book that talks about like the relationship to religion in science and right you want to ask the question like as if i just asked to you phil sort of well is there place for religion within or is there space for cosmology within religion you know does cosmology sort of fit within this religious picture the question you want to ask there naeash is you know Is there space for, like, religion in cosmology? Right.

At least those elements of religion which involve dogma and faith and belief without evidence. Like, 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. 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 shows. showed that the universe had to be like, well, he believed that the universe was eternal

and static, but general relativity, you said that it would all collapse, and so he introduces this cosmological constant, which holds it in place, and then when he realizes that the universe is actually, like, expanding and not, you know, 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 enter, but scientists themselves 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 like, oh, it's so silly and speculative and as if there are billions of multiverses go like, come on, universes. And you track, you very briefly, in like 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 sun 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. 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 just some kind of weird star or something. And then thanks to the work of the Harvard computers, some very, very, like, undersung heroes, women who were sort of 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.

than it wasn't. Then our galaxy was special. Then it wasn't. There were lots of galaxies. And now our universe is special. Where's this heading? You know, I don't want to extrapolate unfairly, but it seems at least plausible 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 like look at the continents and think, you know,

it kind of looks like the America's slot into like Africa and Europe, laughed out of the room, you know? Right. Yeah. And yet, we now know that to be, 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, we just, we just don't know, man. Right. We just, we just have absolutely no idea. Maybe we were 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 is phenomenal. 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 of stuff. 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, 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 and universes that are self-causing.

It's all in here and perhaps we'll have to do this again some time to cover it even more, but I can only recommend that people go and read the book. It's out now, right? It's out now. It is out now. The link is in the description. description so yeah everyone go and check it out but guys thank you so much it's been fun it's been an absolute pleasure Alex thank you so much it was wonderful thank you very much Alex