294. Sabine Hossenfelder — Existential Physics (5)
1 (49m 16s):
You guys have faith in the multi-verse. It's not testable. There's no way to know. And therefore I have my faith that God did it. You have your faith in the multi-verse were, you know, even
2 (49m 28s):
I would totally agree with this. They're both religious explanations and they're both unnecessary to explain what we observe, because to explain what we observe, we just need the values of those four or six constants, or actually 26. If you count all of them that we have in the fundamental theories, you don't need to know where they come from this, just an unnecessary complication. You know, this is the entire story about the multiverse. Doesn't add anything to the explanatory power of the theory. And neither does the God hypothesis. Now, again, this doesn't mean it's wrong, but it mean that it means that science can't tell you anything about it.
1 (50m 10s):
Interesting. So to somebody who would say, are you telling me this all came about by chance randomness, just an accident, a fluke,
2 (50m 20s):
I don't know how it came about. Do we have to have a theory for how it came about you? See, I think part of the reason I'm having a hard time communicating with physicist is that I'm, I'm an instrumentalist all the way down. Okay. For me, the task of a theory in physics is to describe our observations. So it's a mathematical thing and I put in some assumptions and it spits out a prediction, or maybe sometimes it's the post diction for some kind of observables. And that's it. So for me a question, like, are you saying it's just chance that the constants of nature have the values that they have?
2 (51m 1s):
I don't know what it even means. You know, I, this is not something that I can quantify. Like if, if you want to quantify, what's the probability of getting a particular set of Constance, how would I measure it? It's not that I can look at a random sample of universes. We have only this one universe with, with those particular values of the constants. So how am I to know whether they are likely or unlikely? It's just a meaningless phrase to me.
1 (51m 34s):
Is that what you call yourself an agnostic instead of say an atheist or theist?
2 (51m 39s):
Yeah, I would say like for what my scientific research has concerned, I would call myself an agnostic. If you're asking how I personally lead my life pretty much, I'm an atheist. I don't really do anything religious.
1 (51m 57s):
Hmm. Yeah. Well, that word agnostic was coined by Thomas Henry Huxley. When he was talking about the Gnostics who thought they knew for sure the answers to these questions. And he was sure he didn't. So he was agnostic by which he didn't mean I'm waiting for one more piece of research to come in, like on climate change. If I just knew one more, maybe a little more data, I can make the decision. He meant it's not knowable. There's no set of experiments. We're going to run the, ah, okay. There is a God or ah, now we know there is no, God, it's just not going to happen. Sort of, it's sort of an epistemological pick on himself at agnostic in that sense, as opposed to the atheist, the strong atheist who says, I know there is no God, he would say, no, you don't know that.
1 (52m 44s):
Well again, you're writing about existential questions in, in nature and physics. Yes. That's one of them. All right, let's continue with some of the other big ones. Okay. Laws of nature, mathematics, laws of nature. What do they represent? I mean, like, you know, that stars burn at a certain temperature and convert hydrogen to helium. That's a law of nature, but it's not, it doesn't exist. The law doesn't exist in the star, right? It's just these, our own human descriptions of things that are happening in nature in some consistent fashion.
2 (53m 15s):
So that's something which we certainly know. I mean, it's just true that we can use those laws to describe what's happening and star. So in the, in an entire universe, there are physicians who believe that laws have an existence. And then by themselves, there are lots of physicists actually believed that the mathematical structures of the theories exist. They don't, they don't normally openly admitted, let me put this way, but it becomes pretty obvious if you look at the arguments for the multiverse, for example, or also if you just look at a textbook, he looked at the textbook, they will define space, time, hours, and manifold.
2 (54m 0s):
It's not that spacetime is described by a manifold of, you know, with Lawrenson signature on differential or what have you, all those attributes that spacetime is a certain manifold. So, so they basically equate reality with some kind of mathematics. And then it's not so surprising why those confusions with the multiples come about. They're like, okay. So I have a lot of mathematics that describes what we actually observe, but there's also something in this mathematics, which describes something that we can't possibly observe. Therefore it also has to be real. And it's this, it's this last therefore, which is the problem.
1 (54m 43s):
Yeah. I, I tried to read max Tegmark book on this, you know, the universe is mathematical. I met him actually in spent a week with him on a scientific American cruise. I just found him to be the most interesting creative thinker. But I, I can't say I really get the, I understand what he's talking about. Can you walk us through, what does that mean? The universe is mathematical.
2 (55m 2s):
Yeah. I think TIG market health, just taking this thought to the extreme. So he wrote a book that's called the mathematical universe and he's also written a paper about it. And it's a particular type of multiverse where all mathematical structures are equally real. So I think there are lots of physicists who would think that the mathematical structures, which describe our universe, like for example, the, this Romanian manifold of a certain dimension, you know, with, with certain equations on it, they would probably kind of agree that it's real, but they would stop at saying that all mathematical structures are real, but take mark makes this step be basically, I think his argument is kind of, since we don't know why only this particular mathematics should be real, all mathematics has to be real.
2 (55m 59s):
The problem with this is that it's a scientific it's, it's completely meaningless to say that something is real. If you can't observe it. And suddenly we can't observe most of those mathematical structures, the only mathematical structure that we can, in some sense, observe is the one that describes our universe. And I say, in some sense, because you could argue that we don't actually observe the mathematical structure. We just used the mathematical structure to describe our observations, which is being on the safe side of the instrumentalist. So I don't really understand what one gains from this idea of the mathematical universe. I guess it's one of those things that has captured the imagination of some people, but from a scientific perspective, it's, it's pretty much useless.
1 (56m 48s):
Okay. Your chapter, why doesn't anyone ever get younger? Well, this takes us back to where we began. What is time? Is it, is it not in some definition, the second law of thermodynamics, entropy just grinding along, you know, one step to it, the other energies dis dissipating, you may have some external source. You heat up your coffee in the microwave. We have the sun and so on, but ultimately it's just going to run down. So that would be time. It seems like there's an arrow there. No one gets younger, the egg, the crack egg, doesn't go back into the shell, the broken glass, doesn't purge back into a whole glass and so on.
1 (57m 29s):
Isn't that it isn't that the answer it's just entropy,
2 (57m 32s):
Partly this is the answer, but this isn't the end of the story because entropy can only increase if it was small to begin with, which brings up the question, like, why was it smaller than the beginning of the universe? We don't know. So this is what's called the past hypothesis, but I think there's another problem, which is that this notion of entropy, which we're using is very human centric. It's again, based on our perception of what, what is doable basically, you know, what can you reverse? And what can't you reverse more formally.
2 (58m 14s):
We lumped together a collection of micro states in some kind of macro state. But if you look at it fundamentally on a microscopic basis, the universe has always been in one particular micro state and it'll always be in one micro state. So what's the central pay increase that we even talking about. Well, wherever itching over certain things that we can't tell apart. But again, this is something about what we can and can't tell. So I'm very unhappy with this notion of entropy. It just doesn't seem to me like it's something of fundamental relevance. And then to me, this is kind of the mystery. I don't really go deeply into this in the book.
2 (58m 56s):
I think I flesh out the, the problem with the past hypothesis. And then there's the issue with the bondsman brands and all that kind of stuff.
1 (59m 5s):
Yeah. Well, so why do we get old? You touch on that a little bit, you know, the theories of aging, there's several different theories of aging. You seem to like the, we just run down, right? It's just entropy that the mechanical system just ages out at some point. And that that's just entropy, although it doesn't happen consistently. It's not a linear descent from birth to death, right? I mean, I have a six-year-old son and, and you know, his body just heals so much faster than mine. I get a cut, he gets a cut, his cut is healed up. Like you can almost watch it. And mine takes, you know, now weeks cause you know, I'm 68, right. So, but, but his will continue along, you know, heal.
1 (59m 47s):
His body will repair itself pretty well for like the first 30 years. And then, then the decline kind of started slowly. And then around 70 I've sort of noticed in my friends and my parents and so on 75 or so it drops off pretty dramatically. So it's almost like evolution designed is not just to wear down in some consistent fashion, but to kind of push back against entropy through your reproductive years. And then your sort of grandparent years where you, you know, you support your own offspring bringing up their offspring. And then after that natural selection has decided as it were that you're just not that that needed anymore. Something like that.
2 (1h 0m 24s):
Yeah. Well, look, I haven't studied biology. I'm not a doctor. I can't really say much about this. I stayed on the side of physics. Entropy increased gets us all eventually one way or the other evolution suddenly has a say in how fast it's going to happen. But, well, we can't, you know about the loss of nature it's going to help sooner or later anyway.
1 (1h 0m 50s):
Oh no. I was hoping you had an answer to how we can postpone this indefinitely. Well, I don't know. So you, you, you do,
2 (1h 0m 59s):
We're working on it. Ask me again in 10,000 years,
1 (1h 1m 4s):
One of your questions in the book is do copies of this of us exists. As you know, one of the kind of scientific attempts at immortality would be, if you could upload your connectome a copy of all your memories, thoughts, everything in your brain to a giant file and upload it to the cloud. Then you can continue on, well, maybe not forever, but however long, the cloud lasts, something like that a lot longer than the protein meat that your brain is made out of. What do you make of those kinds of arguments?
