Should we abandon the multiverse theory? | Sabine Hossenfelder, Roger Penrose, Michio Kaku

The debate abroad seems to be absolutely fascinating. The mystery of the

multiverse

. Multiverses are everywhere, or at least the

theory

is that everyone from physicist Stephen Hawking and Brian Greene to Marvel superheroes have shown support for the idea, but critics argue that The Multiverse is not only unlikely, but which is also a fantasy and fundamentally unscientific, since the

theory

can never be proven if we reject the grand claims and leave the Multiverse theories to the pages of comics. They are tales of the Multiverse that are really plaster solutions for a Big Bang theory. in trouble or

should

we take the Multiverse Theory as seriously as its proponents and accept that modern science has moved beyond the limits of experiment to those of the imagination, so join me to discuss the topic in a notable panel Michelle Kaku is A prominent string theorist and one of the founders of Stringfield theory, she has written a host of best-selling books, including The God Equation and Parallel Worlds.

Sabina Hoses specializes in the foundations of physics, is a researcher at the Institute for Advanced Studies in Frankfurt and leads the superfluids and dark matter team and Roger Penrose, who needs no introduction, is a renowned mathematical physicist and philosopher of science. world. He received the Nobel Prize in 2020 for his work on black holes, so I'll give each of them just three minutes to address the central question which is: Does the Multiverse exist or

should

we reject the grand claims and leave the theory to science? fiction, so missio is all yours, thank you very much? The most successful physical theory of all time is called quantum theory and is accurate to one part in 10 billion. and the world economy is based on the quantum principle lasers Internet this conversation is possible thanks to quantum theory but quantum theory is based on a spatial principle that electrons can be in two places at the same time now Einstein hated that principle that one once said that the more successful quantum theory becomes, the sillier it seems, sorry Albert, but it turns out that the world economy is based on the fact that electrons can be in several states at the same time until you measure it, now Let's apply this.

Theory of Einstein's theory Einstein says that the universe is a kind of bubble that is expanding, which is called the Big Bang theory. This is correct and we quantize the universe, then the universe can be in multiple states at the same time, in other words instead of a bubble it is a bubble bath and these bubbles can collide and when they collide they form a larger bubble or a bubble it can fission in half to create two smaller bubbles and what is that called Big Bang and how is it demonstrated well? So far the data seems to go in favor of the inflationary theory, an inflationary theory in terms based on the idea that universes are being born all the time, even as we speak.

Big Bangs have been happening somewhere in this great Universe of ours and then where does inflation arise? The theory comes from well, a theory that seems to predict the theory of inflation is called string theory, which is what I do for a living and if I have time later I will talk more about it, but then the question is how do we visualize well these higher interventions. Logan Lori and Steve Weinberg gave us a way to visualize these Higher Dimensions. Think about your living room. In your living room, there are hundreds of radio signals from radio stations around the world in your living room, but your video has been decoded here.

It isn't true. not to the radio station your radio is only tuned to one frequency now replace the radio with electrons your room is full of electrons electrons are pirates dinosaurs aliens from other stars and stuff, everything in our room but you are no longer vibrating in phase with them, says Steve Weinberg, in other words, yes, there is a Multiverse computer out there, but probably its ability to listen to them. I have been consistent with them, it is too small to measure. One problem we give our PhD students is calculating probability. Tomorrow you will wake up on Mars, well it is a finite number, you can calculate it, but tomorrow I suspect you will end up in your room, you will have to wait and walk with the universe to wake up on Mars, but is it possible?

Well, yes, and that's it. what separates this from marvel comics marvel comics all these feats of imagination are free in real physics we can calculate your chances of these things happening and you will have to wait longer than the time of the universe worry about that spiderman thanks michelle so Sabina. So I think all of those Multiverse theories that we've seen emerge in the foundations of physics come from the same misunderstanding: that we have physicists who come to believe that the mathematics they deal with is actually real, so they usually act in the same way. What happens is that they have a theory that makes some predictions that agree with the observations, and they understand that to mean that because some of the things they can predict agree with the observations, all the mathematics that is in a theory has They have to be real and for me. that's completely crazy, you know, it's like saying "okay", so Harry Potter, Harry Potter goes to King Cross, King's Cross station, which is a real place, therefore magic is real, that's not It's a good logical argument, but I think it's a bit of a false dichotomy.

Well let's say it's science or it belongs to comics, there are some things in between, so I think multiple theories have some value as philosophical speculations or maybe some people find them inspiring, they certainly have inspired many artists, writers, etc. , me too. I think that has value too. I think the thing to keep in mind is that while they can't be tested right now, maybe at some point in the future they can be tested, so for most of those Multiverses that's the reason we can't access them. experimentally. is that, as far as we currently know, nothing travels faster than the speed of light, so perhaps at some point in the future we will be able to exceed the speed of light limit, in which case the

multiverse

s could become verifiable.

Thanks Sabina Roger, well, I had already done it. It was a little troublesome when I saw the topic of this meeting. I don't really know what people mean by the Multiverse. I think a lot of the alternatives I've come across I would spend all my time trying to distinguish between them, I think. I will comment mainly on what Mikio was talking about, that is, quantum mechanics and the problem within quantum mechanics. It seems like you have to consider all kinds of alternative things happening simultaneously. Now the problem here is the theory, in my opinion it may well be as mentioned above. the most successful theory we have had the problem is that it can be successful but in reality it is not consistent with itself the problem is that it consists of two parts one of them is what can be called the Schrodinger equation how the quantum state evolves in the time and the other has to do with what happens when we make a measurement and the two things are inconsistent because if you imagine that making a measurement involves a measuring device and that it appears to come from outside the measuring device it is not considered a quantum system. itself is, so it doesn't measure anything, so I have a real problem with quantum mechanics for this kind of reason, it's clearly a successful theory, it clearly has huge implications that we see are in agreement with the physical world, however, has this. big flaw that was quite pointed out by Schroding himself, he described this thing in his hypothetical cat that was alive and dead at the same time and he more or less didn't say, as some people say, well, maybe if you're smart enough you could build a Schrodinger's cat who is dead at the same time as Schrodinger points out the absurdity of the situation more or less to say that there is something wrong with the theory and that is my opinion, that there is something wrong with the theory even though that is the case. a wonderful theory.

What is wrong with the theory has to do with superpositions that are not simply electrons here and here at the same time, but large bodies that are here and here at the same time and, in my opinion, if one considers the fundamental principles of the other great theory of physics of the 20th century, namely Einstein's general theory of relativity, you realize that there are problems of conflict between the general principles of general relativity and those of quantum mechanics and then, in my opinion , it is not just that general relativity must be quantified. In other words, under the general scheme of quantum mechanics, quantum mechanics needs help for itself, and the help it needs is to get rid of all these different alternatives.

One thing happens, not the superposition of all the different things, and one can understand that by exploring how. general relativity is concerned with macroscopic superpositions. Now I'm not going to go into that here is not the place to talk about it but the conclusion one seems to reach is that when you have a large enough body that is in the superposition of two places it has a useful life in that state which very quickly turns into one or the other and a theory that improves quantum mechanics introduces general relativity the right way is not to quantify general relativity, which people often say is a big problem in physics if you know. gravitational quantum mechanics, we have to see what happens when the principles of general relativity are applied to quantum mechanics and then you see that you don't have all these superpositions of different things at once, you can have one thing or another.

The bigger the thing, the more quickly it becomes one or the other into a perfectly coherent scheme. Now I am afraid that at this moment we do not have a complete theory of this nature, regardless of the greatest challenge of physics today: to see how to join these theories together and to rid quantum mechanics of this major flaw, namely the problem of measurement or the fact that superpositions seem to be present in quantum mechanics and we really want a theory that has an alternative that resists all others for macroscopic bodies. Thanks, Roger. Before we embark on talking about a number of different topics that we want to explore with the panel.

I would like to clarify a little bit the question that Roger said against the Multiverse being used to refer to all kinds of things, very different types of Multiverse. where there are some claims that there are infinite universes besides our own and there are different versions of this, so I think briefly to try to clarify what the different positions of those on the panel here are, so I miss you, I understand you. How to argue that there are an infinite number of other universes with potentially different laws than this one, is correct, yes, the screen theory, for example, probably has an inexplicable number of infinite universes and, of course, that raises the question that the people do this to me often.

Well, then that's true. Is Elvis Presley still alive in one of these parallel universes? Well, it can't be ruled out, maybe he is still singing his hits in another parallel universe, but let me make a challenge, a challenge to everyone in the audience, we are dancing around the question. Is there a theory of everything that can unify general activity with quantum mechanics? Let me pose a challenge to you. If someone from the public can propose a theory that satisfies three criteria, it will probably be recognized in the next Einstein. First, his theory has to be recognized. include general relativity at least in the low energy realm your second relativity has to include the standard model with of course 36 quarks and antiquarks three generations of subatomic particles and all the large number of young Mills particles has to include the standard model and three your theory has to be free of anomalies, divergences and mathematical inconsistencies and if ever among the audience you find this table Theory then tell me first, well, we will try to go together on your Rescue Mission, yes, yes, very good, so, Roger, sometimes I think.

Your point of view is described as a Multiverse but it is a cyclical Multiverse, it is the idea that this universe had something before the Big Bang and there was a universe before it and that, in fact, if you look back indefinitely, there are a whole series of um. Expansions and contractions occur in sequence, is that correct? Would you describe it as a multiverse or do you think you actually see that as a universe it's just that it goes through a series of stages, certainly just one universe, there's no multiverse? about that and it doesn't contract, I should say, but it doesn't matter, no, the point of view is completely different, of course, what I was talking about, yes, now it's the topic of quantum mechanics, apparently a multitude of different things, but yeah, what you're doing.

What I'm pointing out is this model that I presented a few years ago, where you have a sequence of phases or eons, as I call them, but they are all part of one Universe, plus things that happen before the hours influence the hours of ways that areobservable. testable and some of these have been tested and we see positive conclusions from these things, so I don't consider this to be really what you were suggesting. I believe this is not a monthly verse in any normal situation. I don't know if we can. Is there a normal sense of the word Multiverse, but it isn't in the sense I've heard?

Express, yes, but thank you, yes, so Sabina, let's cut, come on, the first topic that I would like to put on the panel. Scientific theories have to be testable and does the multiverse theory threaten this basic principle? um, yeah, and yeah, maybe let me expand the sum. Actually, I don't know anything about anyone who works on multiple things or, in general, on the fundamentals of physics, who would question that. Theories have to be testable, instead what is happening is a little more subtle. There are three different arguments that people make about testability in fundamentals, one is that the theory may simply not be testable yet, um, that's a typical argument that string theorists make, so in principle makes some predictions, but we would have to build because the size of the Milky Way to test it, so maybe one day we can do it, but not anytime soon.

The second is a bait and switch tactic where they change the general principle which could be the Multiverse or it could be dark matter or the Theory of Everything. or something for a very specific model, then you have this general idea like the Multiverse and someone comes and says, well, it's not testable, then they can say, well, I have this very particular model for the Multiverse that makes a particular prediction, for example , there are some multiverses. where, um, universes can basically collide and it leaves a signature in the cosmic microwave background, which is something you can look for, but then if someone goes and blocks it and doesn't find it, they say, "Oh, it was just This particular version of the Multiverse that has been discarded, we still believe that the general idea of ​​the Multiverse is correct and it's the same for Dark Matter particles, so you can basically modify your theories indefinitely every time contradictory evidence comes in, you go back and say, well, here's a different model, I'll forget it um the third one um is the argument that I mentioned briefly at the beginning since they say well, I actually have a theory that makes some testable predictions that have been tested, so I also believe. that all the other mathematics is real even if you can't prove it I see, thank you so I miss you um science needs to be testable and your theory is not the spring theory is that we will get four experiments experiment number one, the Fermi laboratory is for the For the first time in history we find an anomalous behavior in a muon magnetic moment which indicates a new force outside the standard model this is huge it means that quantum physics is being shaken to the core if the result holds with the Fermi laboratory a deviation in this added model number two dark matter dark matter will collide with protons leaving a spark in a spark chamber which in turn can be measured and then compared with the different Dark Matter predictions from string theory such as photino el funkido is a particle in a string theory that has no charge is massive and obeys all the properties of dark matter and could be found any day in a spiral chamber three deviations from Newton's inverse square law we know that the universe is three-dimensional because , as we learn in elementary school, gradually the dimension decreases to the inverse square, but what about the inverse Cube?

The Reverse Quantum University. If the universe has a higher dimension, then gravity should decrease in the laboratory, not in outer space, in your laboratory faster than usual. Number four, eventually NASA and NASA will launch Lisa outside. Space Visa is a laser interformal space antenna that is aligned to capture radiation from one trillionth of a second after the moment of the Big Bang; in other words, we hope to get baby pictures, baby pictures of the infant universe as it emerges from the wolf and hopefully, This is, of course, fingers crossed, hopefully we'll find evidence of an umbilical cord, an umbilical cord that connects our universe to a baby universe, and again, these four things don't require a Milky Way-sized particle accelerator.

These results are coming in now, even as we talk about premium episode results about dark matter and discussions about the inverse square law. These are things that can be done in our lifetime and yet we are not talking about direct measurements of these things. Speaking of indirect measurement, we've never been to the Sun, we've never been inside a DNA molecule, but how do we know so much about this sign? Have we been there? Have we been inside a DNA molecule? No, we know that through indirect analysis most physics is done indirectly, so it is a false scarecrow to introduce the idea that it is necessary to have an accelerated particle the size of the Milky Way, that is a direct confirmation of the theory of ropes.

I'm talking the same way we know so much. about the Sun and a lot about DNA molecules by indirect measurements, which leads us to believe that string theory is correct, so I will ask Sabina to answer that in a moment, but at the beginning you pointed out many questions that there are . they're about our current theories of the universe, you know, Dark Matter, the recent muon experiment, etc., but can you really point to them as evidence for the Multiverse Theory? I mean, aren't there many other possible explanations for that and they actually remain? deep puzzles, but you know, the fact that there are deep puzzles with our current measurements of various things doesn't show us that the Multiverse theory has been proven to be so, is that so?

There are degrees of confirmation in other words. having a completely confirmed theory takes a long time think about atomic theory how long did it take us to confirm Democritus' conjecture two thousand years ago that there was something called Adam? It was two thousand years before we had the first clear pictures of atoms, but in between we had many indirect measurements, many indirect theories that indicated that he had atoms and was real. Same with the Multiverse. It will take time to get all the facts in place, but all the facts so far point in the direction. of the Multiverse, okay, thanks Sabino, we may not have direct evidence, but we may have indirect evidence and the parallel with the collider, the size of the Milky Way is misleading, so the observational observations that Mishu just to mention if it was discovered that they would not be evidence for string theory. um, it's just wrong.

I know a lot of string theorists, uh, serious string theorists and I don't think any of them would make that claim and I can explain this in great detail but it would take a long time. maybe maybe just take an example deviations from Newton Square law this is something that people have searched for a long time there are many ways to explain it it could be a new additional force it could be additional dimensions but it has nothing to do with strings certainly It is true that there have been some predictions inspired by string theory that would also lead to these deviations, but we face what is called the inverse problem, maybe one day we will have some observations and try to infer what the theory was. gave rise to them and this is completely undetermined as the philosophers expressed it there is no way out of string theory in particular do you want to respond well to that machine as I mentioned before?

It took two thousand years to fully verify the atomic theory now. We have photographs taken with scanning microscopes, but in between there were many partial results that gave us indirect proof of the existence of atoms. Einstein in 1905 was able to show using statistical mechanics that atoms were probably the size we think they are today. at minus eight centimeters, so I think that not in a single instant we are going to prove that the Multiverse theory is correct or that string theory is correct, but the overwhelming weight of the evidence will point in one direction and allow me to do another challenge , another challenge. everyone in this room is free to not like any of these theories, but if you don't like these theories, come up with your own, the second law of thermodynamics says that it is always harder to create a theory than it is to destroy ethereum, no They may like none. of these theories we talked about today, but I challenge you to find a better one.

Well, there's a great opportunity to introduce Roger in this conversation. Well, I'm not a particle physicist, so I don't claim to have a better theory than string theory. Theory, although I am quite disappointed by the conclusions, I just want to mention how other theories have taken a long time to confirm it. It doesn't seem to tell me anything about string theory. I mean, string theory proposes an incorrect number of dimensions of space, for example. the wrong sign for cosmological constants, for example, all sorts of things that have come out of string theory are just wrong, now this can be fixed one way or another.

I know people like to cram all these extra Dimensions into a little ball that they have. It didn't answer the question I've often asked in my books about it, which is that it doesn't really solve a problem. I mean, there are big problems facing string theory. I didn't really know why we're talking about this. with the Multiverse anyway because string theory is simply a particular theory that I don't think has much support, there are many people who defend it, but that is not scientific support, there are no experiments that support it. String Theory, but that's really a different question than the Multiverse, isn't it?

We're talking about String Theory or the Multiverse here has been criticized for being a Multiverse Theory, oh, but I don't care because even if you take a look. In Newton's laws of motion they are also, in a sense, a theory with an infinite number of possible solutions. Your strong point here is an infinite number of solutions. Well, so are Newton's laws. Maxwell's equations all have an infinite number of solutions, but how does it make sense? By looking at the initial conditions, this is how you can prove that Newton's theory is correct, starting with the baseball, starting with a rocket, the same with the student theory, you start with the initial conditions of the universe and then you can project into the future.

The problem is experimental, we don't know the initial conditions of the universe, therefore we can't directly compare it to a multiverse theory, but that is an experimental question that I think will be answered as we have more and more satellites detecting things like gravity waves in outer space. Okay, I miss you, some people would say that what we have to do when we propose theories is apply the old philosophical principle of Occam's razor that the fewest possible new entities are generated, but the proposal that there are an infinite number other. On the surface, the universes seem to break that imprinted principle.

Don't you think that a more modest proposal could be more comfortable? People are trying. People have tried for decades to trash the Multiverse Theory, but as I mentioned, it's the legitimate interpretation of a mechanic it agrees with all the experiments now there are other interpretations of the important mechanic you don't have to believe in the Multiverse thing if you get 10 to the power of uh, I mean 10 billion one part in 10 billion precision for an experiment there are other interpretations of quantum mechanics, but the Multiverse interpretation is the cleanest and simplest interpretation because you just rule out one of the personalists of the quantum theory, so the Multiverse theory is actually simpler than the quantum mechanics I teach at the City University of New York by discarding the postulate that Make you make an observation and the wave function collapses, you actually simplify the quantum mechanics.

Would you agree? No, no, I don't understand all that. I mean, you get the idea, I mean, these are the many worlds. As for the other things, there are so many things that seem to be related to the Multiverse that I'm really confused about what's been talked about. I mean quantum mechanics, yes, if you don't have the collapse of quantum mechanics. You have all these overlaps that we don't see in the world. There's something you have to do about it, but what does that have to do with the Multiverse? Simply postulating that they are all there does not help and that is different.

Multiverse anyway, it's not the Multiverse where you. Don't know. I really get very confused about how these problems are solved by having a Multiverse. It doesn't help me at all. Well, let me move on to the next topic here. which is whether the experimental evidence for the Multiverse is at least short on the ground, if not impossible, is what is driving the story of the multiple firsts, it is because, in a Big Bang Theory, it is inproblems and we need something to solve, I mean, that's what Well, Sabina, to some extent, it's a sociological question about why physicists do what they do, but maybe it's worth saying a little more about the question about if the Big Bang theory is in trouble.

I can only guess what Michio meant when he talked about gravitational waves in the early Universe. I guess it was the B modes in the CMB. The right detectors, like the Lisa laser interferometry space antenna, are being pushed by the European Space Agency at NASA, yes, but what is the primary signal? gravitational waves, that's right, gravitational weight before 300,000 years after the big bang at the instant of creation itself, yes, right, so why would this be evidence of the Multiverse? I guess because you say it would be evidence of a particular type of inflation, is that the idea because once you have data on true intimacy after the big bang you can play the videotape back and see what the alternate universe really is in a second before the Big Bang coincides with the data a trillionth of a second after the big bang and so in other words, in this sense, we can obtain data before the creation itself, before T is equal to zero, by extrapolating the subsequent radiation to the Big Bang to the pre-Big Van era and then, of course, string theory offers a number of predictions about all three.

The Big Bang universe is what flows and if you find that result for everything, you can calculate the free radiation from the Big Bang and compare it to the post-Big Bang radiation. Of new space-based gravity detectors, yes, but What does it have to do with the Multiverse? Because this allows you to extract the key, the keywords, except the set puts everything in London. You know which of the Multiverse ideas is correct, just as you do. this newton quads has an infinite number of solutions for baseballs, rockets or marbles and an independent resolution which one is correct depends on its initial condition, we do not know the initial conditions of the Big Bang once we have the initial condition of the Big Bang , then you can start ruling out universes that don't match and out of the Multiverse you can get the birth of our universe itself, so starting with a Multiverse Theory you then get the theory of the universe itself.

By running the videotape backwards well, but obviously only to describe our own Universe, we don't need all the other infinitely many universes, so all the other universes that are do not correspond well with the experiment, but maybe let me go back a little. so I'm not saying that all those other universes don't exist. I'm trying to say that science can't tell us anything about whether they exist or not, it's just not in the realm of science. I don't have a big problem when people talk about multiverses of any kind, whether it's the many-word interpretation or eternal inflation or the string theory landscape, etc.

I have a problem if they say it is science because it is not, it is a strange type of platformism where scientists come to believe in the existence of mathematics, as I said every year, as more data arrives from CERN's fermilab every year, We will have better and better data that will allow us to focus on this theory without having to build an accelerator the size of the Milky Way, we will become asymptotic and we will get closer and closer, just as with the atomic theory, every year we get more evidence of atomic theory, even if we don't have photographs of the atom itself.

What happens with string theory, we will get closer and closer because more data will come that I believe will verify string theory, but it is not one of the challenges of this proposal has been that if a general proposal is made to take into account how As things stand these days, as I say, you normally want to operate within the principle that it should be as simple as possible, you've argued well, it's pretty simple. I think the principle of Occam's razor is that you don't generate entities unnecessarily and an infinite number of universes just break that principle by training horses, but other people have said well, if you're proposing something as an explanation for what's here but you don't have evidence of this, what difference is there between a Multiverse proposal and the traditional religious proposal of God? which you say well, we can't explain everything here, let's posit that everything is made by something else, i.e.

God, there is the idea that everything here comes from the Multiverse, it's actually just a scientific version of theology, no, I do not know. I think so because every time someone makes a theological statement, it is based on their own marriage or whatever forever because there is no experimental evidence to support it, it is just pure conjecture, but as I mentioned, there are at least four main ways to verify the theory and each one. brings us closer to a complete verification of the theory, not an experiment that confirms it at once, there is no irrefutable proof, but the same with the Big Bang theory, there was no irrefutable proof for the Big Bang theory for many decades , so what I'm saying is that it brings us closer to the truth, but religion does not bring us closer to the truth.

They are the same arguments formulated thousands of years ago that are identical. The arguments that will be made 1000 years from now in religion, do you think? uh Roger, one of the reasons the Multiverse has been proposed and the version that Michelle is presenting is because of the concern that quantum mechanics has built into it and the uncertainty that Einstein was certainly uncomfortable with and in some ways you're trying to get rid of the unknown in quantum mechanics and say well, let's just generate entities for each bit so that it's no longer unknown, but if that's what you're doing, it's not very impressive.

I mean, quantum mechanics has a problem and I think that's true regardless. being the most wonderful theory we've ever had or something, it has a deep problem, but I don't see why that has anything to do with this Multiverse problem that has to do with string theory, I mean, it seems like there's a big confusion about different concepts, different problems that people have and calling them all Multiverse or something like that, I don't see it solving any of them, I actually mean that Maxwell's equations can have many solutions, yes of course they do for Einstein's equations and Newton's equations, why does that lead us in the direction of a multiverse?

I just don't have that argument at all and what do you think is driving that? I mean, it's very popular, right? It sells books. sells theories, uh, pushes science fiction, what's with the idea that you know another universe other than this one we find so attractive? I had no idea, maybe if I could say something about it. I think it depends on what we mean by popular, possibly popular in the sense of popular science, you read popular science articles about it, people write books about it and those books celebrate where we go to festivals and people talk about it, but If you look at what's really happening in the community in physics, there are very very few people working on it, we have the fundamentals of physics and then, because there is a subdiscipline of the fundamentals of physics, we deal with quantum gravity and then there's a subdiscipline of the subdiscipline where there's a fringe part where people talk about the Multiverse and say that it's not in any way significantly popular in physics, it's just not true, which begs the question of why the general public finds it so interesting and I find it quite easy to understand, it's interesting brain gymnastics.

You know, I like to think about the possibility that there are infinite copies of me somewhere in the universe and that they are living their lives in other ways. I like movies about that too. I like it if it appears in the books. I know it's good fiction and I don't necessarily have a big problem with it. I just think we shouldn't combine fiction with science. Michelle, that's good fiction. Well, yes, I mean take a look at psychology and cells. The idea of ​​the parallel universe is not new, it goes back to the Ancients, they talked about dream worlds, they talked about hypothetical worlds or in fact, look at Alice in Wonderland, the gateway to Wonderland is the Wormhole, the first conceptualization of a wormhole in English was through the looking glass by Lewis Carroll, also known as Charles Dodson, a professional mathematician from Oxford, so it is an old topic, but the new of this old issue is the fact that it now has a basis in physical reality until now.

The theory of the multiverse applied to quantum mechanics, which is the theory of many worlds, agrees with all the data; in fact, there is no way to differentiate the Copenhagen interpretation from the many-worlds interpretation. They are identical with respect to experimental verification, so it is not necessary to believe in Multiverse Theory to be a quantum mechanical physicist because the data from the many-worlds theory and the data from the Copenhagen interpretation are identical, but when you start to Talking about cosmology, if you start talking about the universe where everything came from, then you start asking these philosophical questions about where the universe came from.

Is there another copy of Me In Another Universe somewhere? That's what resonates with the audience. I think because people wonder about these things. There is a poem by Robert Frost. The road not taken and you always wonder what. What would have happened if I had taken that other path with a fork? This is an internal question and this is why it resonates in Hollywood because we now have at least one physical theory that entertains the concept that yes, there are many paths to reality. Thanks Michelle, so let me finish briefly with a final issue: will we always be in a situation where our broader explanations of the universe have elements that cannot be tested?

Well, I don't think they can be verified, but in principle they can be verified. We just don't do it. I don't have enough energy or enough money or anything like that. I mean, a lot of things haven't been tried because they're quite difficult to do. An example of that is the question of state reduction in quantum mechanics or collapse. of the wave function, of course you have to have a good alternative theory about what level you expect to see and there are experiments being proposed at the moment, some that have been done and haven't gotten there, maybe it will take a long time, but these They are honest experiments that will show if they turn out the way I hope, there is actually something not quite right in quantum mechanics and that all these other universes don't exist and so on one thing happens and that happens in a given lifetime and you can get a good estimate according to some of these schemes and it seems to me that this is how science progresses.

I mean, you suggest experiments and some of them are quite expensive, so they take a long time for people to decide to do them or they can be technically very difficult, like the ones I'm talking about here, but that would be considered an argument against the multiverses. I mean, I guess now a very good experiment comes out that shows that quantum superposition becomes one or the other in a given lifetime, which is perhaps predicted now, does that say, well, we don't have to talk about multiverses anymore or Is it really a completely different argument that is presented here?

I just feel like they're too confusing, too much, particularly string theory arguments, which I don't really see, I guess I do. I want to go to a little general question: is there something about the way we put our theories together that means there is something? There is always an element of untestability somewhere, so as an example of the kind of thing I'm talking about, a Heisenberg can certainly be interpreted as advocating the view that physics is not discovering reality, and that's because because it cannot do so in some cases. At some level there is some residual element that has to do with the limitation of the human being and making observations would mean that we cannot understand it.

Another way to think about it would be, you know, are there elements of science, for example, the notion that the universe is governed by laws, which is an essential idea for science, but you know, can we actually test the idea that the universe is governed by laws? Is there something in it and therefore are there some essential assumptions? we were in some theory that we can't understand well, I mean, I imagine that tomorrow all the laws will change and I mean that could happen, I don't expect it to happen, but I can't see it, I mean all the observations that have been updated, I mean, tell us that the world has to be according to the physics we understand now.

I mean, it just seems to work pretty well and very well under certain circumstances and, um, I mean, take general relativity, it's now. extraordinarily well tested, I mean things like a clock down here works at a different rate than a clock up here, well, you know, it used to be this Tower, no, it's from here to there, sure, I mean, these things They are confirmed, they are really precise things. The theory says that they can be doneexperiments and they say yes, this theory agrees that this is what we observe now. String theory is nothing like that and there is nothing like that in these postulated ideas about other universes around, so I can't understand why we should consider them.

The ideas are comparable to these wonderful things we get from physics. We know so, Sabrina, do you think there's always a residual element that we can't lift? So I was about to say pretty much the same thing as Roger, um, I think that's underlying. In the scientific method itself there is always the problem of inference, as you express it or as you draw it, he popularized it with his chicken analogy. The farmer feeds the chicken every morning at exactly 9 a.m. and think. that this is a law of nature until one day the farmer comes and cuts off his head, so we don't know if the laws of nature will still work tomorrow.

This is something that underlies all scientific methodology that we assume to be true, but we can't prove it in and of itself because how would we? Yes, of course, but there is a somewhat more innocent example of something we cannot prove, which is something that is too rare to happen at the time we measure it with an example. It may be proton decay, which is something we've been looking for for a long time, but we still haven't seen a single proton decay, but there are also other things like, for example, the cosmological constant may not be exactly constant, it may be very very slowly change over a couple of billion years, but we could never prove it and I think it's an interesting example because what the cosmological constant does eventually determines the ultimate fate of our universe and do you think there's something there? a place to propose theories that we don't have evidence for or maybe can't have evidence for, but that somehow work to hold together our overall view of the world in some ways that are there.

There is some purpose to that exercise, even if we think well, actually this is not really science, it is something else. I think there's a purpose to that. I think it's worth thinking about whether you can have a scheme that is simpler in some respect and may not be provable, but on the other hand gives you a general picture that is simpler than one that is different but still not provably different. , so it's certainly worth thinking about those things, but I think he's really crossing the line when he was talking. about this Multiverse, ideas that partly come from things about quantum mechanics that I think are not correct and one day I hope to see what should replace them, but I can't understand why we should get carried away with this idea of ​​all these universes coexisting.

But I haven't understood that, so he's a missionary, do you think there will always be other issues that we can't explain and that can't be verified at some level? Yes, there is a point where all known physical laws completely collapsed and that is Planck energy, the plug energy is 10 to 19 billion electrons evolving, which is a trillion times more powerful than Our most powerful machine, the Large Hadron Collider, is the point at which black holes and Big Bangs take place in the realm of chronic energy where Einstein's equations become useless. Einstein's equations diverge completely on the flank energy.

The laws of quantum mechanics. You have to have higher loop diagrams to control diversity. It is a real disaster, but that is the energy of the center of a black hole which is the energy of the Big Bang, the most interesting place in the universe is beyond our mathematical ability because they exist in the energy of the plug, in fact, The only theory that can operate on the energy of the product is string theory, but that's another question, but the question you ask is: is there a point at which the laws of physics say that we know that they decay and the answer is yes?

Two places, the center of a black hole at the beginning of the universe, that's where punk is. Energy begins to reach the wormholes that dominate, all kinds of crazy things begin to happen, we have to think about the possibility of time travel, gateways to universes, it becomes a real disaster with the block of energy, yes, obviously the question is whether we take those descriptions seriously, right? I do not think that it's necessary. I mean, the Big Bang is fine. I don't want to get into this because the Big Bang is a different story than singularities and black holes which are completely. different story and trying to apply the same arguments to both is, in my opinion, quite incorrect.

I mean, I myself had the wrong view for a long time, so no, there's nothing against contemplating these things. I just think about what I consider good. There are reasons why singularities in the Big Bang are completely different in nature from singularities in black holes and this difference is extremely important because it leads to the second law of thermodynamics. It's part of history. If they weren't different, we would do it. It does not have a second law of thermodynamics. I mean, these are things in physics that we see very obvious things in physics that, if we trace them, lead us to the conclusion that what happens in the Big Bang is completely different from singularities and black. holes and therefore put them in the same category and say String Theory or multiverses or something like that is going to be resolved, I can't see it at all, very well, I'm afraid that's all we have time for, I think we'll all be agree on an absolutely fascinating conversation.