294. Sabine Hossenfelder — Existential Physics (4)
2 (37m 19s):
So this is like really weird. It's got nothing to do with, with quantum mechanics. I don't know why people come up with these things. I, I guess it's just too, because it sells, you know, because it kind of sounds magical mystical quantum flop, fluff doodle. Is that what the phrase that you used to have to keep this in mind? So I, I find it a little bit frustrating and one of the big problems is that a lot of people who don't know a terrible lot about physics, it can't really tell that it's just, it's just nonsense.
1 (37m 54s):
Well, again, I think that part of the appeal besides selling books or whatever, because I don't think that's the only motive is again, it's dealing with, you know, the most existentially significant ideas in, in all of life. It's, you know, like the ultimate questions, maybe the answer is in quantum physics and you kind of have this intuition, we have this kind of natural born dualism. I feel like I'm a body and a mind or brain and mind, it feels like there's something else floating around up there. And then when the physical body dies, it, it kind of floats off somewhere. So the question would be well, where does it float off to? And so, you know, quantum field. Oh, that sounds, yeah, that seems possible, right.
1 (38m 35s):
That with, without knowing too much about how that could possibly work, I think, I think something like that is the appeal. And anyway, so, well, let's talk about, okay, so just sort of going through your big chapters here, you know, how did the universe begin? How will it end? Yeah. So this is the problem of, it's almost an epistemological problem. You know, you just keep going back in time, you know, to a theist, it would be like, you can't just say, well, it came out of nothing. And then someone like you would say, well, I don't mean nothing. I mean, there was a quantum field and there was a little fluctuation in the quantum field and it came out of that to which the person would say, well, where did the quantum field come from? At some point they want to postulate. Well, there was a creator that created the quantum field and then the universe came from that or whatever.
1 (39m 20s):
Give us the physicist answer to, you know, where, how did the universe begin? What do we know?
2 (39m 26s):
We don't know how the universe began. So I mean, what we can do is we have a pretty good idea what the universe is doing at the moment it's expanding. And we're pretty confident we have the right equations. They came from Albert Einstein and we've tested them forwards and backwards. And so we can just take the current state and ask, well, what happened earlier? So naturally since the universe is currently expanding, if you look back in time and it contracts. And so everything in the universe becomes denser and denser until at some point about 13.7 billion years ago, it reaches a state of infinite energy density and infinite curvature.
2 (40m 7s):
And we call that the big bang. And we're pretty sure that this is not what actually happened. It probably just means that the equations breakdown. So what actually happened, we don't know. And I I'm skeptical that we will ever know, but now you may wonder, well, why, why do we have all those stories about fluctuations from a quantum field that you just mentioned, or like Roger Penrose has this idea with the cyclic universe or something else that you might have recently seen mentioned this, that we came out of a black hole or a Mo what else? The no boundary proposals. And, you know, there's a long list of these ideas of how the universe began.
2 (40m 50s):
Why are there so many that's because as we briefly discussed at the, at the very beginning, you can just make up some mathematics for it and it looks impressive. And then you can get a published and there are literally infinitely many of those theories that you can make up and physicists haven't yet written papers about all of them, but they're getting close as we speak, I suppose. And so, so the problem is just that you, you can go back in time and then you can change the equation just because you want to, at some moment, there's no evidence that speaks against it. And there are many different ways that you can do it.
2 (41m 30s):
And they were with enough fumbling and with enough effort, they will all reproduce the observations that we have today.
1 (41m 39s):
Is it your sense that psychologically speaking, most people are not comfortable with the answer you just gave, which is we don't know. And it's like, oh, come on, give me something to work with here.
2 (41m 52s):
That's, that's part, that's part of the problem. It's like, they want to know they want to have a story and different people want different stories. So they make them up. But pop the, I also think they're genuinely confused about how much science can do. They, I think most businesses would disagree with me. They think that those theories are actually scientific and I would, I would disagree with them. I think it's not something that you should do. You shouldn't invent stories that are actually unnecessary to explain what we currently observe.
1 (42m 32s):
Yeah. You use the phrase in your book, a scientific meaning what, whatever it is you're talking about, it's not science, it's something else, metaphysics or philosophy or speculation or whatever. I like that you kind of push for a more pup hereon philosophy of science. If it's not testable, it's not really science. I think that's good. That works for most things. Although do scientists actually work in a pop hearing way? Are they working to try to falsify their own theories? Are they working in a more Basie way? Like, let's see if I can accumulate enough evidence that I could tip it up to 51% likelihood that it could be true and then run from there. How do you think about science that way?
2 (43m 13s):
So I actually don't think the Papa's all that helpful. I would say that businesses at the moment rely way too much on Papa because it's probably the only philosopher of science that they've ever heard of. And this is the only thing that they know about him, that he said a scientific theory has to be testable, but what they conclude from it is it is what they conclude from it is that they think if a theory is testable, then it's scientific and which, which is of course obviously wrong, because there are many ideas that you can put forward that are obviously testimony.
2 (43m 53s):
They are not scientific. The example that I like to give us that tomorrow, it may rank carrots. Okay. So, you know, that's, that's a totally testable idea, but he wouldn't get it published in a scientific journal. Why not? Well, because it's not scientific. And now you, you can try to figure out why we think it's not scientific, but that that's a different story. Now, the issue is that physicists that are foundations and, and this is the case in cosmology, astrophysics also dark matter, all the kind of stuff, but also Collider physics. And some other areas is that they put forward some kind new idea, you know, there's a new particle, and then you can calculate what the consequences of this particle would be under the let's say, and it's testable, therefore it's science.
2 (44m 42s):
Okay. And I say, well, this is just a guess wrapped in mathematics. That isn't any better than me saying what tomorrow it might drain carrots. And so of course what happens with all those predictions, like all those, there were literally tens of thousands of predictions for stuff that should have shown up at the large Hadron Collider, but they're all wrong. Unsurprising. The, I would say in just like my prediction that tomorrow it'll rain carrots will also turn out to be wrong.
1 (45m 12s):
That's funny. So would you put the multi-verse idea, whichever version you want, you know, sort of splitting off quantum effects where there's a new universe at every split or there's multiple bubble universes out there that are not in contact with each other? Is that just an, a scientific, I don't know, metaphysical idea. It's not testable or is it derivative from the equations or how do you think about that?
2 (45m 40s):
Yeah. And it's kind of both though. There are some versions of the multiverse, which suffer from the problem that we already talked about, w which those are those which are testable, where we just say, where you just, you just guessed something. There's no reason why it should be the case. Like, like there are particular versions where you can have collisions between universes. You must've heard of this and it it'd leave an imprint in the cosmic microwave background, or, you know, you could have entanglement between different possible universes, that kind of stuff. And, and those would leave an observable signature. And that, that brings us back to the problem we just talked about, like, this is, this is not a scientific way of putting forward a hypothesis.
2 (46m 25s):
Now, if we leave those aside, then we are left with multiverses, which are not testable because we're disconnected from them. They are snow possible experimental evidence that we can ever gather. That'll tell us that they exist. And that doesn't mean that they're not there. It just says that science can't tell us whether they are there or not. So this is why I say it's a scientific, why do physicists believe in it? That's an interesting question. And I think your guests is pretty much right. They think that they can derive existence of something with mathematics, which I think is just badly misunderstanding what mathematics can do for you.
1 (47m 12s):
Hmm. Right. Let me set this up with the problem of the kind of fine tuning that you talk about. I like to use a search Martin Reese's book, just six numbers. And this is where we end up with the multi-verse explains these problems. So his six numbers are a mega the amount of matter in the universe, if which is one, he says, if, if it were greater than one, it would have collapsed long ago. And if omega were less than one, no galaxies would have formed to Epsilon. How firmly atomic nuclei bind together, which is 0.07. If Absalon were even fractionally different matter would not exist.
1 (47m 52s):
Number three D the number of dimensions in which we live, which is three number four, and the ratio of the strength of electromagnetism to that of gravity, which has 10 to the power of 39, if an were smaller, the universe would be neither, either too young or too small for life to form number five, que the fabric of the universe. One divided by 100,000. If key were smaller, the universe would be featureless. If key were larger, the universe would be dominated by giant black holes and then six Lambda, the cosmological constant, or the anti-gravity force that is causing the universe to expand at an accelerating rate of 0.0 0.7. If the Lambda were larger, it would have prevented stars and galaxies for, for, from forming.
1 (48m 35s):
Okay. Now, Martin, as far as I know, doesn't go, therefore, there's a God that fine tuned it. He, I don't think he does that, but a lot of people, as you know, do they go, well, there has to, if there's all these six fine, two numbers is picture a board where those sound boards with all the dials, just say, those are the six most important ones that suggests that there is a fine tuner and yet not all physicists do that, but some say, well, the multi-verse right. If you have multiple universes and they all have these different knobs adjusted, they end up with different kinds of universes that we just happened to be in the one that has that particular configuration of tuning. Therefore, but now when I present that argument to theists in my debates with them, they go, Schermer, that's just fate.
