Into the Impossible With Brian Keating - Martin Bauer: The Revolutionary Stern-Gerlach Experiment (#305)

Episode Date: March 24, 2023

Please support the podcast by taking our short listener survey: https://www.surveymonkey.com/r/intotheimpossible Watch the video of this episode here: https://www.youtube.com/live/hiw3aJwc7TU?feature=share?sub_confirmation=1    The Stern-Gerlach experiment is one of the most important results in physics history. Shockingly, the paper had never been translated into english until today's guest, Prof. Martin Bauer set himself to the task. We'll discuss the experiment, as well as Martin's research. Bring your questions for this renowned science popularizer and scientist! Read the paper: The Stern-Gerlach Experiment, Translation of: "Der experimentelle Nachweis der Richtungsquantelung im Magnetfeld" by Martin Bauer https://arxiv.org/abs/2301.11343 The following is a translation of the paper by Walther Gerlach and Otto Stern that reported the first evidence for the quantization of atoms in a magnetic field. The atoms have quantum states corresponding to a limited number of possible angles between the directions of the angular momenta of the atoms and the magnetic field, also called space quantization. The wording and layout have been chosen to be as close to the original as possible. For context we recommend the recent review. Martin Bauer is Assistant Professor (Research) - UKRI FLF in the Department of Physics . His Research interests include: Dark Matter Heavy Quark and Lepton Flavour Physics Higgs Physics Research groups Elementary Particle Theory Institute for Particle Physics Phenomenology https://twitter.com/martinmbauer Subscribe to the Jordan Harbinger Show for amazing content from Apple’s best podcast of 2018! https://www.jordanharbinger.com/podcasts  Please leave a rating and review: On Apple devices, click here, https://apple.co/39UaHlB On Spotify it’s here: https://spoti.fi/3vpfXok On Audible it’s here https://tinyurl.com/wtpvej9v  Find other ways to rate here: https://briankeating.com/podcast Support the podcast on Patreon https://www.patreon.com/drbriankeating  or become a Member on YouTube- https://www.youtube.com/channel/UCmXH_moPhfkqCk6S3b9RWuw/join To advertise with us, contact [e-mail] Learn more about your ad choices. Visit megaphone.fm/adchoices

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There is a directional effect in quantization so that basically the angular momentum is quantized leading to this effect. It's something that was implicitly clear before, like there was indirect proof of that, even though people weren't actually convinced that this effect would be there. It's the first direct proof that this existed. It is a pioneering experiment if you think about it. There's the first vacuum to that degree. It is the first molecular beam that they had to that degree.

When that experiment was built, Boar himself said that it was a very, it was a very, it was a that he didn't believe it might work. For the time of great confusion where this experiment just basically put a nail in the coffin of classical mechanics was clear there's no way this could be described by anything else as by a new theory that was about to appear. It should be emphasized that all theories that we have have untestable consequences and not directly accessible to us. The fact that we know that these kind of theories predict something like the multiverse should get people into the business of thinking about whether it can be tested. If it can never be tested, it's not something we could waste our time with.

If someone has a brilliant idea of how maybe there is a test that nobody has thought of yet, then we should take into account because that could tell us whether these theories are right or not. Welcome, everyone, to this deep physics episode of Into the Impossible. Prepare to expand your science vocabulary and understanding as host Brian Keating and Theoretical Particle Physicist extraordinaire Martin Bauer unpack one of the most seminal physics experiments ever done. Supported by Einstein himself, the Stern-Gurlach experiment has become a quantum mechanics benchmark that stands out over 100 years later. You're going to get an in-depth look at how science is done and the history of quantum mechanics.

This live stream episode includes questions from you, our outstanding audience. If you appreciate hearing firsthand from scientists like Martin Bauer, please consider giving us a boost with a five-star rating. Keep in touch with Professor Keating by joining his email list at briankeating.com slash list. receive his Monday Magic newsletter. And if you have a dot edu domain, we'll send you a bit of space dust in the form of an authentic meteorite fragment. Please help make the show better by filling on our listener's survey, link to in the show notes. And let us know what you think of the show in the form of a review, like this one from T.C. Cook. Such thoughtful, challenging, and interesting conversations. I learn a lot every time I listen. And now, enter the quantum realm.

as we go into the impossible with Brian Keating and Martin Bauer. Any sufficiently advanced technology is indistinguishable from magic. Open the Bob Bay doors, please. Everybody, you are in for a real tree today. Kind of an unusual scenario where I have a friend in the Internet age that I met from great distance, and he has become a friend, but we haven't met in person, although we are going to meet in June when I give a talk at the Royal Institution. I will provide you more information about that soon. And that's Professor

Martin Bauer. Martin is an assistant professor. No, you're an associate professor, right? How does it work? Associate now, yeah. Associate now, congratulations. In the Department of Physics, and he has been working, this is at Durham, yeah? Right. And it has this, this moniker, this acronym in front, UKRI, which I know means United Kingdom Research Initiative, research initiative, and then FLF. What does that stand for? Well, that's a future leader fellowship, which funds my research at the moment. That's phenomenal. So he is a current leader in the explication of some of the most difficult, hard to understand,

but in his capable mind and brain becomes transparent, even to simple. experimentalist like yours truly. And Martin has a knack for that. And he's been doing that on Twitter. He's grown exponentially. And today we're talking because not of a book. Normally Martin, we have authors that have written books. I hope you'll write a book someday and we'll always have you back on the podcast whenever you're available. But he's on to discuss a very important paper, which I encountered 30 years ago as a beginning graduate student. And that's called the Stern-Gurlach experiment and we'll talk about what that experiment has meant to physics. But the reason that he's on is because of a chance, maybe serendipity brought him to this project. And that was by Chanda Prescott

Weinstein, who's a professor at the University of New Hampshire. And she made a outrageous claim that this paper, which is so foundational, so fundamental, was not available in English. And, you know, I only know a couple words in German, Martin, and one of my favorites is crankavagen. Are you familiar with that word? Of course, yes. Which I believe means ambulance or cranky kids when I take my kids to school. Anyway, Martin translated this paper. Actually, you should just read it because I want to hear your melifluous German accent.

So if you would please indulge us with the actual German title in German, of the paper that you translated, spurred on by our colleague, Chonda. So the paper is called the experiential the experiential naeis der Richtungsquantlung in Magnetfeld in German, which is actually not so easy to translate, because Richtungs quantilung is something that doesn't really exist in that sense, and it's not something that has a direct translation into English. So what people did is calling it space quantization,

And it kind of matches what people had in mind back then when they did the experiment, but it's not actually what they discovered. I'm sure we get to this. Yes. And what makes it so important to physics that would warrant it being translated only about 100 years after its actual publication? What does this experiment mean to science in general, but specifically to quantum physics first? What was the immediate impact of this paper?

So that's two different questions. So looking back, what they did is they discovered the spin of the electron. And they're not only discovered the spin of the electron, they also discovered the spin of the electron is quantized. So it can only have discrete values. It cannot have an arbitrary value like classical angular momentum. Back then, what they were out to discover, or what they were out to disprove,

at least half of them were out to disprove that, is that thing that they called space quantization, that meaning that there is also just a discrete number of angular momentum values, but for the atoms, for the whole atom. So Bohr had that idea, the Bohr atom model, prescribes that the electrons surround the nucleus on some orbits.

We know now this is not an exact description, but back then it was helpful to describe the biomass series and discrete spectra, discrete lines, and that were discovered. And back then, There was something called the Zeman effect, line splitting in the magnetic field. And people back in the 1910s to 1920s, when this was discovered, tried to explain it within that model. And it didn't quite make sense.

And eminent physicists like Boer himself and Somerfeld had the idea that maybe this angular momentum that basically tells you the plane in which the electrons were about to rotate about the nucleus can only have discrete values. We can only point to certain directions. So Boer said that that might be helpful in explaining it. And Somerfeld actually had a paper where he said, this can have three values. It can be like aligned with a magnetic field or orthogonal to the magnetic field in two different directions.

And then Sterling Guller set out to test that. They said, well, if that's the case, we can put on an inhomogeneous magnetic field. That results in a force on anything that has a magnetic moment. And if this is true, we should observe. a number of spots where these atoms end up once they traverse an immogenous magnetic field. So that was the actual experiment. They had a little furnace, they had silver atoms, and they had very, very much at the forefront of the technology back then, they produced a vacuum, funneled them the silver atoms through a little hole at the furnace, then through this magnetic

field and put them on a little plate to see whether this discrete spectrum actually appears, appears or whether there is a continuous spectrum, as you would expect if it was a classical angular, like that's a magnetic moment. And so if you imagine you have a magnetic field and you move like a bar magnet through that field, depending on its orientation, it will be deflected up or down. And if it has some angle with the magnetic field,

it will be deflected somewhere on the spectrum. And the quantum theory said that's not going to happen. What's going to happen is you will only have a discrete number of spots on the screen because there cannot be any value of this angle momentum. has to either align or misaligned with a magnetic field. And Stern, who was the person who had the idea for the concept of this experiment, he actually didn't believe in the bore model at all.

He wanted to disprove it. He had heard of this and he had thought about it. He said, well, if that's true, we should have seen it before. We have, like, if you have like an hydrogen gas, for example, and you put light rays into the gas, there should be an effect that you see because the magnetic field within the magnetic field the atoms would adapt and the life would be absorbed and not absorbed depending on how that looks like so he was very skeptical in fact there's a famous quote of him that he's he's a quote as saying if this nonsense of bore proves right in the end i will quit physics he was really opposed to that idea which i should add is something that is to be said about

physics in general you don't need to believe in the hypothesis that you are testing the you're motivation might as well be that you want to rule it out. So he was strongly opposed to this model and he actually would have been very happy to find that it's not true. But at my last, they found this spectrum, they found two spots, one up, like a splitting in this line and that proved in the end that that wall only a number of discrete possible values for this angular momentum. They didn't know there is anything to do with the electron back then. They still thought they had proved the bore model. They actually sent the postcard to to bore congratulating him that he was right in the end.

But a couple of years later, it became clear what we have now in textbooks that this experiment showed that the electron has a spin, a quantum angular momentum itself. And that was the . . . . . which doesn't disprove the bore. I mean, the bore model is wrong. Let's get that out of the way, right? It's useful, but it's wrong. And I think that has a lot of parallels to some of the scientific debates and disputes that you and I sometimes engage with our colleagues about.

on Twitter and other fora. And that's that, you know, something can be predictive and actually correct in a certain level of approximation, but ultimately falsifiable. The atom is not a tiny little planetary system, as we know now. But that was incredibly useful. And in fact, we can use it as we can use Newtonian gravity to get to the moon and the planets. We don't need Einstein for that. We can actually use it for most of the spectroscopy that we would do in the lab where there

aren't tiny little effects. One thing I've always wanted to ask you, Martin, and as the token experimentalist who appears on my channel, I can always ask these questions without fear of reprisal. But that's, is there such a thing as an unperturbed atom? I mean, when I teach quantum mechanics, we start off with the shrughering equation. We start off with this notion that there is a little planetary system like borne vision. And then we broaden it out. We add in actual perturbations. And we'll talk about what is the perturbation that leads to the stern Gerlach effect and that leads to the splitting and why does it require an in-homogeneous magnetic field, not a homogeneous one. But is there such a thing as an unperturbed, you know,

system or is it only just sort of a useful paradigm in which to do predictions for theorists? I mean, in the sense it goes to the heart of quantum mechanics that you can't really have such a thing. Or put otherwise, say, for example, you are a brilliant experimentalist that works in atomic physics and you isolate an atom, you put it in a trap, and you shield it from all the magnetic fields of the earth and whatever could potentially have an effect. You will, for example, never be able to screen gravity. These effects are so small that they'll never make any effect that is going to perturb the kind of physics that you want to test with this atom. But there are physical effects that are impossible to get rid of and more generally is also the interaction with the detector

itself if you want to measure an effect in a quantum mechanical system you have to actually interact with the system itself we have to interact with the atom in that case right so that'll perturb it as well so but coming back to your point about theories i don't think there is or i'm not sure there is such a thing as a as a perfect all-explaining theory i think one lesson of physics of the last 100 years at least is that whenever we find a new layer, it is just that. It is another layer of reality. It is precise up to a certain energy, which we can test it, and then we can't really say whether it is exact or not.

And more often than not, theories get replaced by something more precise, which doesn't make them wrong at all. It just tells you that the realm of applicability of that theory is not infinite. that you can't go to infinitely short distances or infinitely high energies and use even general relativity will break down eventually. So it's not clear to me that there's any theory that has this property, at least in the paradigm of effective field theories, this is one of the lessons we have learned that basically you go from shell to shell and learn a little bit more, a little bit more, and a theory

is a little bit more precise, but they can always think of situations where it's going to eventually break down. So I'm showing the paper, the archive reference, and I put that in the show notes down below as well. So you start off at the preamble about the motivation for this, the actual reference. So the paper's over 100 years old. They published in 1922 with the title that you gave it. It's actually Gerlock and Stern, which I didn't know that. But at any rate, we know it as Stern Gerlock.

So it talks about the space quantization. let's be clear. When you talk about, when we talk about space quantization, these scientists are not talking about something general relativistically. They're not talking about quantization of, you know, at the plank length or something like that. I'm not saying space is quantized, correct? What are they saying? No. Yeah, that is an unfortunate name. It is the name that was given to the, and the literal translation would probably better be directional quantization. That's more close to the German word. I just kept in line with what people used back then that wrote English literature. So when we did the translation, I should also mention Philip Helbeck, he's a cosmologist who

helped me quite a bit with translating the paper, being a native English speaker. So we did this together. It's a longer story why he is not the archive version. He will be on the journal version, though. And what is meant by this is that there is a directional effect in quantization. So that that basically the angular momentum is quantized leading to this effect. It's something that was implicitly clear before, like there was indirect proof of that, even though people weren't actually convinced that this effect would be there. It's the first direct proof that this existed. It is a pioneering experiment, if you think about it.

There's the first vacuum to that degree. It is the first molecular beam that they had to that degree. When that experiment was built, Bohr himself said that he said that, he didn't believe it might work. So there's another famous quote that I double-checked just for this podcast. It's Gerla who answered to Boer that no experiment is so dumb that it shouldn't be tried when he was mentioning that he was unsure whether it might work. So it is really, really difficult experiment back then.

And it took the mobile to get it to work. But eventually it worked out. And with regards to the space quantization, the effect is different from me. all that had been seen before because all quantization effects that you had before, like the Balmer series, for example, they showed that there is a quantization if you excite an atom. So an excited atom will show you these lines or an excited atom in the magnetic field can give rise to the Z-man effect. But this experiment showed that the ground state of an atom, there was no excitement at all,

still has this quantization property, still confirmed quantum mechanics. And that is why it has this had this fundamental impact. back then. So I'm showing figure one from the paper, which demonstrates the source and the beam. Yeah, that's true. I didn't realize that it was the first kind of molecular beam experiment, which would later lead to things like nuclear magnetic resonance and the work of Robbie and other tremendous contributions to our knowledge.

And as well as really making an impact, it's rare that an experimenter has an impact both experimentally, technologically and also philosophically. And I think the strange thing about this is that it really highlights the notion of spin, doesn't it, Martin? So what do we mean by spin? How do you think about spin? There's a book by Tomanga called What Is Spin? I read it. Didn't really come away with a much better appreciation of how to visualize it. Is it impossible to visualize because we're these macroscopic creatures? How do you visualize as one of the most recent? the respected theorist of your generation. How do you visualize in a working sense?

What is spinning? What does it mean? And just restrict ourselves to the electron for now. So when I try to visualize it, I can't do better than you, anyone else, I think. You just think in terms of what we know from a microscopic world. So when I think in my mind about the spinning electron, I literally think of that.

It is like a little point like a tiny sphere that spins around its axis. That is not actually what's going on. as we know from the mathematical description, but it interacts with everything around it as if this were true. So the spin of an electron combines with angular momentum as macroscopic angular momentum would, with the only difference that it is quantized.

But that's also true for angular momentum itself. Like every system that has angular momentum also has quantized angular momentum. Just have to probe it carefully enough. And once you have enough spinning or rotating objects, then you get this macroscopic situation where you don't see the quantization property. But what concerns to my imagination, I don't think I can do better than anyone else on that regard. It is fundamentally different, though, because in a way it is closer to mass than to angular momentum.

Because spin is a fundamental property that is independent of the inertial frame in which you look at it. So whether you look at a system spinning or someone moving, look at the system spinning, the spin of an object is invariant. It's a consequence of the fundamental symmetry group of space time. So it is a quantum number that is not related to some internal symmetry, that electric charge, for example. It is related to the same symmetry that gives rise to boosts and to mass as the other fundamental quantity

that is invariant between inertial frames. So that is, I think, a bit of a deeper insight that you get, if you look at the fundamental theory that gives rise to spin. But if I try to imagine what a spinning electron is, I don't think there is a way to improve. I haven't seen yet a better description. So I'm showing on the screen now that figure two and three, which show the behavior of the impact on an emulsion.

So talk about these two different diagrams. I always thought the one on the right, which is the scale, the rule, is inverted or it's flipped left to right and upside out. But it always looked kind of like somebody's mouth, like, you know, with a little thing underneath the nose. What is this depicting? And why is this so indicative of the fact that these have spins and not some other quantum

phenomenon? You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get. Lost. Or you could book a stay with Hilton.

Welcome to your oceanfront room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton for the stay. So in the left picture, what you see is what you would expect classically.

You have a line and the line would broaden. if you funnel different atoms with different aligned angular momentum through the magnetic field, because the angular momentum would in this picture spread from left to right. On the right-hand side is what they actually observed, where the magnetic field turned on. So if the classical theory would have been right, then you would have seen the left picture, which is taken without the magnetic field, and once you turn it on, the line would have broadened, would have spread out a little bit. But what What happened instead is the line split into two lines. And that is exactly the effect that the quantum theory predicted.

In fact, there were two competing. So I mentioned before, Somerville at the time, was convinced that there would be three lines. There would be a line for perpendicular to the magnetic field and aligned and anti-aligned with a magnetic field. So he was thinking there might be three lines showing up, but Bohr had some argument that the central line is unstable and should be only two. These predictions back then I should add are not what takes place here in the end. In the end, it is the spin of the electron that has only two possible values that spreads the line. But this is what happens. The electron can only project to two possible

spin values, spin up or spin down with respect to the magnetic field. And so it ends up either on the left or on the right of this picture. And why do we get this, why do we get the closure of the lips on the, you know, on the sides. Why don't we just get two parallel lines, Martin, if there's two spins? Oh, I think because the magnetic field is not, there's an in homogeneous magnetic field that is not perfect. But I'm not an experimentalist, so I can't give you the details about that. I think that the electrons that were not funneled centrally for that field, we're not feeling its full effect, so they weren't really deflected as much. And I believe it's true if the apparatus was physically larger, the separation would be greater.

it's sort of the product of the length traverse times the in-humid. Now, it has to be an inhomogeneous magnetic field. Why don't we explain why that is the case? Why can't it just be two refrigerator magnets, you know, creating a north and the south pole? Why does it have to be this strange, inhomogeneous magnetic field shown, generated by this odd-looking pole-type behavior?

So if you had an homogeneous magnetic field, meaning a field where the field lines are all power low, for example, and that magnetic field the spins might still project to that field lines. So there's a magnetic moment. The spin of the atom has results in a magnetic moment because it feels the magnetic field. And then it might still project to these lines.

It will still align the atoms. But there is no force in an homogeneous magnetic field that would actually make them split to the left and to the right. So they might still travel through it, but they will not be split. That is why it was necessary of this inhomogeneous magnetic field. feel and I want to re-emphasize and that is actually the accomplishment of Gerlach out of the two. He actually made this experiment, the one that told Bore that they should try it even if the things is impossible basically.

He made it work. So Stern had the idea and he wrote a paper previously where he, that is translated into English. It's also on three pages or something where he is very unhappy about Bross proposed and he says, I'm going to prove that wrong basically. We have to build this experiment. But only when Geller arrived in Frankfurt, he made it work. So it is technically really difficult. Back then, it is an incredible experiment that they made work,

and that in homogeneous magnetic field is part of what made it hard. And why did they have to use silver? Why did they choose to use silver and not some other atom? So silver, well, we know now that silver has a single electron that is responsible for its spin. I don't think, because they weren't aware of that back then, I don't think this is the motivation of why they use serve in the first place. They could have used other atoms as well. I think there's an experimental consideration there that you have to have it available.

You have to be able to turn it into a gas. You have to be able to handle it safely. So I think these were the considerations. But I might be wrong. I don't know exactly what motivates them to use server specifically. But this is the reason we need two lines. I'll say that again, that silver results in two lines. yeah. So I think part of the reason might have been that, you know,

photographic emulsions were using silver, you know, halides and stuff like that. So it's probably convenient to use silver for the exposure. Perhaps that was one of the reasons. Now, this experiment then takes on kind of a life of its own, right? So they, they go on to get some great fame. And I love to read acknowledgments. First of all, I love a short paper. I mean, as much as anybody, this would have been fun to do. I like to look at the foundation. Let's see, it says the electromagnet necessary with funds from the foundation of the Kaiser Wilhelm Institute to the director, Mr. A. Einstein. Is that first name Albert? Albert Einstein's first assistant.

Long before he moved to Zurich, he knew him very well. And he moved with him to Zurich. And then when Einstein went to Berlin, Stern moved to Frankfurt, where he started working. with Geller and this was just after the war so money was really hard to get by and there was actually heavy inflation setting on much worse than today even though we like to complain but there was a different time so they didn't have the funds for this experiment really and to keep it going they had to write letters they had to ask for funding and Einstein was asked in a letter for 8,000 rice mark and he gave them 10,000 so he was

really in support of this experiment. When I say he gave, obviously he supported them and getting it. It was not his money, but as a director in Berlin, he was able to make that work. And that's not the only money they received. They bore wrote letters for them too after he saw that Geller somehow was in a position to make that work. And I don't know how this worked precisely, but I think he knew someone in New York and Goldman from Goldman Sachs fame, Really? He had family in Frankfurt and he funded this experiment as well with several hundred dollars, which was a lot back then. Wow. So they navigated that with a lot of external money that they had to bring in, not unlike today when we do our experiments.

So often people think, oh well, back then they had these cheap little experiments that were easy for them to build. And it was just a matter of a few hundred bucks or whatever to make that work. But it was a terrible, terribly hard. to get the funding for this experiment as well. It hasn't changed as much, even though the digits might have changed. And this was a busy time for Einstein because, you know, when they're doing the experiment, that was around the time he had, well, he won the 1921 Nobel Prize, but it wasn't given to him until the following year for reasons I don't quite understand.

Maybe you do. But this is quite a busy time. And I like that they're, you know, really cooperating with the, with, with teams at different institutions, and it's quite, of course, in service of the truth, which is this, which is this, you know, kind of bizarre notion that the electron may have this, you know, not only hidden, but philosophically almost troubling type of behavior. And what's kind of delightful to me is that later on these types of phenomena, the spin of the electron and other things, would go on to make Einstein rather nervous about the underpinnings

of quantum mechanics. So maybe talk about the influence of this paper and the notion of spin being a really honest to goodness intrinsic property of the electron or any quantum system. What did this do for philosophy, in particular to Einstein, perhaps? So, well, there was, there was, there's a lot that happened following up the experiment. There was an immediate impact. Einstein and Ian Fest wrote a paper within weeks on this particular experiment. It was clear that they showed something that was such an important proof of quantum mechanics. The theory wasn't worked out back then, what I should say.

So this was in a time where, as we mentioned, the war model was basically what people went off on. So they didn't have the full quantum mechanics that were still in its very early years. So they didn't have that. They just showed basically that the current best theory of nature, classical mechanics up to that point, apart from the early science of quantum mechanics didn't quite work again. And they showed that this is the case if you have ground state at hand as well, not just some excited states or photoelectric effect or something like this. It really was a fundamental property of nature.

And Einstein-Eherz wrote this paper basically double-checking this. They wrote a paper where they checked whether there could be any way the classical effect might lead to this picture. It was really consistent. So Stern, who was opposed to the war model and in general had a big problem with these quantum mechanical effects. So he didn't expect it at all. He didn't believe it still. For a long time, he struggled with the notion that this might be fundamental.

And Einstein-Ehrin first wrote a paper and I think one of the points they made is that there are some classical effects. So there's a lamo frequency. There is a way that you might imagine they can somehow align in an atomic field. and they tried to build a model that this works. And St. Founder would take 100 years for this classical effect to make this final picture work out. So it was for the time of great confusion where this experiment just basically put a nail in the coffin of classical mechanics.

It was clear there is no way this could be described by anything else as by a new theory that was about to appear. And yeah, eventually the theory was worked out by Heisenberg and schrodinger later on there was a lot of work going into this stern actually well there i don't know whether you want to go there right now but um because you mentioned the noble price einstein proposed a noble prize for the two i think the year after this experiment as well so he was really um in favor of that it took much longer for stern to get it he got it in 44 i think mcgherlach never got it um that goes because girlah so

So Stern was a Jew. He had to leave Germany 10 years later. I think he went to Pittsburgh after that. And just after he made another important discovery, he measured later that the neutron and the proton have an anomalous magnetic moment, meaning they're not fundamental. So looking back, this discovery by him and others was probably as important almost as the Stern-Golach experiment. And Gerlach was he was not a fan of the Nazis.

He never joined their party. but he eventually was involved with the German version of the Manhattan Project. So he was working on an atomic board. I'm not a historian. I should basically put this. That never stops physicists from commenting on history. Yeah. So he was involved with that.

And that's part of the reason why when in 43 or 44 the Nobel Prize went to Stern, it probably did go to Stern only. He was proposed many, many times for the, for the, price. But Gerloch later on, I should say, was also very much involved in anti-nuclear movement in Germany. So he didn't like the consequences as many physicists did later on. So he did not receive a price on that price for his work. Right. But you want to go to something else, I think. You wanted to go to the implications of quantum mechanics. Yes. Especially the, I'll say it, say it in the,

German please, say spooky action at a distance, even though Sabina will correct us both that Einstein never said that or he didn't mean that or we don't know because we're idiots. Martin, what did it first say it? I can't resist to have, it would be like me having Falco on and not asking him to sing Rock me on Medeus or whatever. Anyway, how do you say it and what does it mean? It's called spookafter fan viacom. It's spooky action and distance is actually a pretty good translation of that, I would say.

And what is meant by this is that in quantum mechanics, you have two different aspects. You have the wave function that describes an object basically before you measure it, and you have the measurement process. And that process, going from the description of the evolution of the wave function to the actual measurement, is not well described within quantum mechanics. There is no real recipe for what happens there. So people call it the collapse of the wave function. There are several interpretations of this, but it is a non-local effect that Einstein baptizes a spooky action at a distance.

And it becomes most obvious when you think about entangled systems, entangled systems by which you can take a wave function that not describes a single particle, but it describes more than one particle. that then obviously you can take apart, you can move them in different rooms, for example, and perform a measurement on one object that gives you information immediately about the other object, which then within quantum mechanics, it's completely rational to expect that because they are described by a single-wave function,

but for us, looks very spooky. Einstein didn't mean specifically that. He made a more general argument that this non-locality is spooky to him. There's a spooky action. the distance, but it is often mentioned in the context of entangled states. And when we talk nowadays about the Stern-Gurlock experiment, it's often, you know, kind of presented as a way to not measure properties of quantum systems, but to prepare

quantum systems. So can you speak about some of the strange things that happen when you have a series of black boxes filled with Stern-Gurlock apparati? You can do all sorts of things. You can prepare things in spin-up states and then send them through another Stern-Gur-Lak experiment. So the output of this will be two beams, right? One will be spin-up, one will be spin-down, the two different lips of the pattern that I showed earlier. And then you can kind of block one of the lips off or one of the beams out.

And then you're left with a pure spin-up or spin-down, just depending on your coordinate system, beam. And then you could put that through subsequent Sterling-Gerlach experiments at different angles. And then all sorts of strange things happen. You want to describe some of the phenomena that you can obtain with these S-G experiments? Yeah, so what you would think is that when you have prepared a beam in a certain state, and I should mention that when I said that these were the first real molecular beams, they had molecular beams before. It's the first polarized beam of atoms, right?

So they played around with this quite a couple of years before. they did the actual Stern-Gur-Lah experiment. But you would think if you have prepared a state in a certain situation, like for example, a spin-up in a Stern-Gol-A experiment, there would be in that spin state. But if you now have a subsequent Stern-Gurlach, so you have one in-homogeneous field, say, that has the, which is aligned up-down,

and you have one that is aligned left-right. And now you filter out the S-Up component, for example, and you funnel it to another, to the second experiment, it will split again. we will see the split now in the other direction. So these kind of experiments were actually also directly proposed by Einstein to make sure that this is what we really see. There's really quantum mechanics. So he immediately started writing letters and said,

let's do two, let's do three. So he was very much involved with the development of the cross-checks of the theory. And it's good to do that because this is something that could have been wrong. The notion of spin could have been falsified, or could have been that we truly have a classical universe, I think that would have made other problems come about. But it's always sort of reminded me of Newton's experiments with prisms and color theory and so forth. So, you know, when you send a beam of white light through a prism,

it'll separate out famously into a rainbow like spectrum. And Newton realized that you could actually experimentally block, you know, say the green color of a beam that was coming out of this prism, say. and then combine it in another prism, and you wouldn't get white light out. And so he realized that it was kind of synthesis, and there was this duality associated with it. I wonder if there are experiments in your mind nowadays. What is sort of the analog of these types of measurements? We hear so much about new forces, new fields, and so forth, really being manifest.

Is there anything in your mind as a theorist that is as exciting or potentially as revolutionary both the physics and to philosophy, teleology, et cetera, as the Stern-Gurlock experiment. So the thing is we don't know, right? We don't know. We have no clear prescription of what experiment precisely will bring this about. We are in a slightly different situation back then.

We don't look through a theory. We have a theory, in fundamental physics at least. And we have one in cosmology as well. They both don't like each other, Einstein's general relativity and the standard model of particle physics. and we have some ideas how to combine them but the fundamental problem with testing these theories like string theory for example has nothing to do with string theory directly it has only to do with the fact that gravity is so insanely weak that it's completely incredible to believe that we

can build machines that can test the energies that would be necessary to see for example a quantum effect in gravity so that is the problem with that but there's a that's not a reason to not test whether something is out there and the most successful version of that for example is what we've seen through gravitational waves in the last couple of years so if you want to me to give an example right now i would think what is exciting are atomic interference experiments for example if you ask exciting and related to stenggela So atomic waves can interfere in the same way as the interferometer of lasers work in LIGO, for example. And you can split atomic waves and you can recombine them, and the interference shows you whatever interacted on the way with the atoms. And these experiments have become incredibly, incredibly precise in the last couple of years. And not only that, people have figured out in the US, there's an experiment at Fermilab,

measures that tries to achieve this in the UK, we have iron. There's an experiment in France as well. They have achieved the separation of these states before interference over very large distances. So you can split the atomic wave, like you can split a laser beam, you can move them far apart, and then you can recombine them and look at the interference pattern. And these are so incredibly precise these machines that eventually they will be able to pick up gravitational waves themselves. They will test a completely different spectrum than the gravitational waves that are tested, LIGO or Liza or any other experiment can test,

which will be almost like a telescope. We'll be a telescope of gravitational waves on a different line width. And we should do all these experiments. They are complementary to each other. They achieve an unheard sensitivity in their particular range of wavelength. And we don't know what they will discover, but they will be surprises. So LIGO already finds that there are black hole mergers where we don't really thought they were. And they tell us something about how black holes are distributed.

That has consequences that will teach us about the theory that is responsible for the distribution of black holes, which are formed in the during the history of the universe. Who knows what we will discover there? So these are extremely exciting. And the particle physics front as well, so whatever the next collider is going to be, it will have the main goal to learn about the Higgs boson, which you just discover. It's just so by the time Sterling Gulloch made their experiment work, the Bama series was known for much longer than we know about the Higgs boson. It probably is not going to be true once we have a new collider to test it, given that it takes a long time to build these things today.

And we'd probably need more money than Einstein was happy to give Sern Gullough for that too. But we really should make that point clear. we have only seen that the Higgs boson is there. We have measured its most immediate properties. We know it's mass. We know it's charge. We know it's spin. But the Higgs particle is only the harbinger of a mechanism that gives mass to all particles

that is predicted by the Sondar model. And the only way to really understand whether this is true in nature is to measure the potential of the Higgs boson, to figure out whether it's actually the particle that's responsible for that, as described by the Sunderer model, or whether it's different. And because it is the only spin-zero particle, it has unique theoretical possibilities to interact with other particles we haven't seen yet. So there's something called the Higgs Portal, which is only possible for a spin-zero boson. We only have ever seen one of them, which is the Higgs.

So we really want to test these things as well as we can and see what they will tell us. We're going to take questions from the audience. Just a reminder, anybody who subscribes. to my Twitter or YouTube account should certainly follow Martin. I've linked his Twitter account in the show notes. If I didn't, I will. And a reminder that I do take questions on Twitter and on Instagram and on YouTube where we have recently surpassed 100,000 followers.

And I want to thank everybody out there and all my guests. And Martin's my first new guest in the new era of 100,000 or more coming up on 102,000. Yeah. So we have great guests coming up on the podcast. If I can get the budget from YouTube, you know, maybe they'll give me some budget to get a non-autofocusing camera. But we have Mark Kamikowski, who I'm sure Martin knows very well. He's a guest coming up this weekend. On the podcast, we talk about tensions in cosmology. And so the kind of way forward that I always like to do is to get questions from the audience because my guests are unequivocally well suited to answering questions. And so there are a bunch of questions, you know, kind of percolating.

But I'm going to take the opportunity to just harken back to what you just said about the Higgs boson. As the only spin zero particle known to physics or cosmology, does that give you more confidence in the existence of inflation and the multiverse, perhaps? or does it have any real impact on the physics of the extremely early universe? So I'm not a cosmologist, so I'm calm. No, I know that. No, no, I know as a physicist, yeah. If you were, you know, to speculate, would you say it gives you more credence in the theory of

inflation or does it not have a bearing? It can't give less, right? I mean, but could it give you more hope that inflation is actually a correct description of the extremely early universe? I don't think it does give you a direct link. I think there are models where the Higgs itself is the inflatron. So the Higgs might be self-responsible for inflation or link to that mechanism, but there are some models in a landscape of models that could be responsible for that.

And I don't see why they are particularly motivated. I think they have their problem. You would really need to ask a cosmologist for that. My opinion, the multiverse is that basically the multiverse is a consequence that can't be tested. If cosmology is right, if certain class of inflation models is true, the one that seems to be favored by the data at the moment, then the multiverse is a prediction of these models, but nothing we can directly test. And I think this

really has people fantasizing about this and calling physicists crazy for coming up with a theory like this. It should be emphasized that all theories that we have have untestable consequences. They're not direct. directly accessible to us. Like Newton's gravitational theory tells us that there is going to be a stone and if you drop it on a planet and Andromeda is going to fall down. But there's no way for us to go there and check.

We can't really take an apple there and repeat his experiment on Earth, even though we definitely assume that it is true as well. And the multiverse is similar. It's not something we can test. It is not scientific in that sense. But it is a consequence of a theory that can be tested otherwise. we should perform these tests. And the fact that we know that these kind of theories predict something like the

multiverse should get people into the business of thinking about whether it can be tested. If it can never be tested, it's not something we could waste our time with. If someone has a brilliant idea of how maybe there is a test that nobody has thought of yet, then we should take into account because they could tell us whether these theories are right or not. Very good. Okay. First question for Martin comes from a person by the name of Kool. cat, although he has an ape as his avatar, she has an ape as her avatar. Brian Martin,

is spin a matter of observational orientation? That is, could you look at a spin-up particle and it becomes a de facto spin-down, adding, not a physicist, but enthusiastic, amateur, hungry for more insight. So is it just a matter of like turn your head and not become spin-down, or is there something intrinsically different about a spin-up for spin-down particle? So what you call spin up and spin down, it actually depends on the way you look at it. You can define your axis and you can define the spin with respect to that. The important bit is that you have these two different orientations for an electron. So once you measure an electron, but you can use a magnetic field, for example,

then what you call up and down, you will do with respect to that magnetic field. But that's the underlying principle. So spin up and spin down are two distinct properties. But if you don't decide to do the experiment and call spin up, spin down, and I call it's going to have the same physics in the end. All right. Cool cat has now subscribed to your Twitter following mass. Join the crowd. So another person, Gibson LP, says chat GPT will render you basically unnecessary and superfluous Martin. How do you feel about that? Is chat GPT or success? call it chat GPD, or what is it called now?

Chat GPT4 right now, they just released this week. Imagine GPT 40. Is there going to be an artificial bower or is your job security safe, at least for NET? So for now it definitely is. I try to ask a church GTP some question that it gets many of them wrong. But I definitely believe that it's going to get better.

And I think it will have its place in helping to understand and develop theories. of theories. I know that Martin Rees has this idea that artificial intelligence will just run away and will have no way in catching up. But I'm not concerned at the moment I would need to see something way more impressive. Even though I think JetGTP is very impressive, I use it. If I need to write a very boring text for a ground application, I let JetGTP improve my English and fill in some words I can't come up with to make it sound a little bit better. better. But in terms of like developing new physics, it's not very helpful. And even if it could,

it would definitely not be able to replace the experimentalists, which do the real physics, right? So if you have a artificial intelligence, it builds us a new collider. You can get back to me. I'm happy to retire then. If you can write a little letter like Einstein did to my funding agencies here in the US, I'd appreciate it. Well, one thing you could use it for, you know, is kind of, of you're generating tweet ideas and you have this prolific ability to connect very abstract, very advanced concepts for millions of people to see. I mean, just this weekend you had one about general relativity in two dimensions. And what I love about you and what you do is you never dumb it down.

You never make it like super simple. You include all the notation. And I think that's inspiring Martin because people see that and it may induce a young, you know, Martin or Brian Keating to go out and become interested in the game that is particle physics and experimental cosmology and theoretical physics and theoretical cosmology. So I want to talk about some of the, what I call the academic media hype and complex, which is kind of like the military industrial complex, which is we have these discoveries and there's new physics found.

And just yesterday or two days ago, you resulted something, you know, I talked about something that could have been a departure from the standard model. How serious should people lay audience people that may be listening and wondering, how seriously should they take it when they hear a physicist? What should they do? Give us a rubric. When you hear new force of nature discovered or, you know, cosmologist, you know, the Big Bang is in violent disagreement with these observations.

What should a lay person do when they hear? hear such a claim? So what I would say is that, so the first thing that everyone should do is read beyond the headline. If you ever have written an article, I've contributed to something, you will know that the headlines of these articles are not even set by the people that write the articles themselves. They are said by the journal and they are set such that they attract as many clicks as possible. They're not set to have the most realistic representation of whatever is described by the

physics has been discovered. And then I would pay attention to the general. So when you read something in a journal online, say for example, then pay attention to what else do they write. If every other article they write tells you the standard model is broken and the Big Bang is wrong and there has been a wormhole and ship and what else, right? If every article sounds like that or every article tells you that physics is finished and we have found the solution to everything or not, right? If it's an extreme hyped kind of a sense that you get from the general articles there, then don't read these kind of journals. If you find a more balanced view, then you're at the right place.

And I think to my surprise, kind of, because I didn't plan that really, I didn't start that way when I started twittering about these things, the people that rather were quite interested and I kept going. But I didn't anticipate that so many people would stay. interested in these kind of technical topics from time to time. To my surprise, if you find the right people on Twitter, this is a really good place to get comments on these articles. So people that are on Twitter are more likely, in my opinion, if they are experts on a topic,

to tell you whether something you read is wrong or whether it is just completely hyped up for no reason. So this is also good to just get a second and a third opinion if you think you've found something that sounds believable to you, but maybe quite a little bit too good. a little bit too negative. Good, to be true. Okay, RuPaul Chana asked, do you think that we should get funding

to train large language models on physics, conversations, classes, derivations to solve specific problems, not just right proposals? Should it be a topic that can be funded, in other words? Not just, I definitely think it should, let me just say my bin, because I love to talk,

well, I love to talk about my sense. myself, Martin, if you haven't noticed, on my favorite subject. But in all seriousness, I do think it has a utility for discovering new ways of pedagogical impact. For example, we could take, I translated, I didn't translate. I took, I was granted the permission from the publisher, which is the University of California, to take Galileo's dialogue and convert it to an audiobook. And it is the first audiobook ever made by Galileo. And we had people like Frank Wilcheck and Carlo Rovelli and Jim Gates and Fabiola Giannati and my friend Lucio Picciarillo.

And we recorded it. And I was thinking this is about a million words. And Galileo's amazing writer. Why don't I just dump it into some chatbot? And then I can go away and we can teach, you know, freshman mechanics by from Galileo, not for Brian Keating, even though I think I'm a great teacher. I can't compare with the maestro. So I definitely, I'm just assuming we're going to use it for teaching and improving the pedagogical method that you and I employ, which is no different than what Galileo did 400 years ago.

And it's even no different than what they did in the University of Bologna in the year 1089 when the first university came about. Some guy or gal scratching with a piece of rock on another piece of rock and there are some students in the audience. Except back then, Martin, the students could go on strike. So if they didn't like us, they would go on strike. We wouldn't get paid. So thankfully that barbaric, you know, inhumane process has gone away. But I guarantee it's going to be. Now, I don't, I'm not a sanguine that it can be used to discover new laws of physics.

And I always use this example, but, you know, stop me if you disagree. But, you know, do you know what Einstein called his happiest thought, Martin? His happiest thought? No, I don't know that. He said that an observer in free fall would experience no gravitational fuel. So I always ask the question, how could you train a computer to, A, a visualized free fall, you know, do a godankan experiment, a visualized free fall, A, and B, how could you connote what it means to feel happy? And it seems to me that that was the most

important thing to Einstein. He talked about something deeply hidden in magnetic fields and quantum mechanics, spooky accident at a distance. These are all very human-centric visceral sensations. So maybe to expand upon RuPaul, do you think that beyond just taking conversations and language that an artificial intelligence could actually come up and create creatively a new theory of physics. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. So I think these models in the artificial intelligence in general, and again I should appreciate us that with saying I'm not an expert in the top. No, that never prevents me from saying anything.

Right. I fully expect that I will have a huge impact on all research fields, right? We already see people that, for example, let them feed in a whole medical library and ask them for drugs that haven't been discovered, and they just scrambled together something that might have an application, right? So they will have a huge impact. I'd like to compare them with, say, computers in general, before computers were around or calculates in the first place.

When a theoretical physicist is one to work out a new model, you sit down and every single calculation had to be done by pen and paper, and you had to look up values of logarithms in books that had been written by Russians a couple of decades ago or something, right? And then you have to double-check some integral values, and it was a really, really difficult, slow process. And computers have revolutionized that. Using computer programs, I can now write a program myself

that gives you a simulation for something. I can immediately get this insight with on my fingertips right it's an incredible revolution and I will be similar it will be very similar to that I think it will be a new tool that will improve the way we approach these problems enormously but one thing won't go away I think it will only be re-emphasized by the advent of AI and that is that what makes a real scientist a great scientist is to figure out the right question to us so this is already the case right everyone who does research knows that you

can work on a certain topic forever. And then when you finish the research project, you figure out, oh, well, if I had phrased it that way, it would have been clear to me what is going on. I could have solved this problem much faster, right? So this has been true forever. Back when Einstein figured out special relativity with all the Duncan experiments that you were talking about,

with the train and the elevator and whatever he was thinking of to make this analogies and to figure out how the dynamics really work and why general relativity is basically impossible to avoid if special relativity is true. If he had asked, for example, an AI, give me a theory that respects Lawrence symmetry, which was already realized in Maxwell's equations.

If you give me a theory of mechanics that respects that, and I doubt that GTP would be able to do it without knowing it already, but a future I might be able to do it, but to find that question, to narrow it down to that question that can be answered that way, That is really the achievement of a great scientist. And still, also, I should remark more and more that this is only true for the theoretical considerations. I don't see AI replacing experimentalists.

They might improve some methods, but as it is now, they don't see them building the next best experiment. All right, let's talk about experiment then. What will we tell this is from Omni Bejesus, which I consider for naming one of my kids actually, Martin. I don't know if you knew that. Omni-Begesis asks, what will we test at CERN in the coming years? And then how can we draw a line between the beginning and end of it all and what will be around this line? And then the tree of, okay, forget that. Let me just ask this first question.

He should have stopped at one or she should have stopped that one. Omni-Begesis, come on. What's the most exciting that's coming up that will be tested at CERN in the next coming years from your perspective? So there's a bunch of things. Stern will start the program of or continue the program of figuring out what the Higgs really is. It will improve measuring the couplings of the Higgs. With the discovery of the Higgs bologn, we have so far only tested a handful of its interactions with the other quantum particles that we know of. And we want to see as many as we can.

Because every single one of them is predicted by the standard model. And if even one of them is wrong, we know there's something else out there. But that is only one aspect of CERN. So the large Hadron Collider is a Hadron Collider, so it collides proton with protons. And you build such a machine when you don't know what you look for. If you already know what you want to test, you don't do this because it's really, really messy. You have a lot of backgrounds. It's really, really, really hard to get predictions tested at the Hadron Collider.

You could collide electrons or maybe you collide muons in the future and there would be a much, much clean experiment. But the big advantage is, advantages then that even though you might look for something in particular, you have the potential to see anything. And the new phase of the LHC, the third run of the LHC will have an enormous statistics. It's billions of billions of collisions. So that means even if you have tiny, tiny effects, you can tickle them out of the data. And that is of course important for the Higgs boson because it is really difficult to produce

a Higgs boson. But more importantly or equally importantly, I'd say, there's also mesons in the standard model, like B meson. they make from bottom quarks or caons, for example, that have extremely rare decays. They are so rare that within these billions and billions of collisions that you have, and you produce billions of these mesons, you only have a handful of these decays.

And some of them we haven't ever seen, and we will only now be able to see them. And these tests are really important. They are basically over-constraining what the standard model tells us. So every one of these tests could show us something that we didn't expect. And it might be counterintuitive, But the tests of these light particles that we perform at the Large Hadron Collider, we all physicists together basically, they are sensitive to extremely high energy scales.

And this is a feature of quantum field theory. You can't have any kind of physics at any scale completely detached from the rest of the world. If you put enough energy in or if you have enough statistics, you'll see these effects. So if we see an indirect effect of this kind, like a decay that happens more often or less, often than the Suna model predicts, that would not only tell us there is something we are missing, like the Stern-Garlaug experiment, right? That's something that what it is is not perfectly clear,

but it also will tell us at what energy scale this takes place. And these implications are incredibly important because they will guide the next collider machine that it will not be a Hadron Collider necessarily, that if we have these hints, we will build a machine that look specifically there what it is that we see that deviates from the prediction. Good. So John Beal-Nielsen asked the following question.

You mentioned the measurement problem of quantum mechanics. What are your thoughts on that? Could new physics come from understanding this problem? It definitely could. I mean, that is the big problem with new physics. So it's not a problem. This is a feature, if you will. Apart from certain guidelines that we know need to be resolved, right? So, for example, if you have a theory that is not consistent, then it can't be right. So you're missing something. You have to go after that, right?

But if you have ticked all these boxes, like the standard model, if you include neutrino masses as well, is a type, is it kind of that theory that apart from gravity, it really takes all these boxes. What guides us to find a new physics is impossible to predict. If you knew it, we would have found it already. Yeah. And the measurement problem is one feature where I don't think there is anyone who would be. claim that this has been understood 100%. There are certainly questions. I'm not a fan of theories replacing quantum mechanics.

Nothing I've seen sounds really appealing to me, to be honest. I think there are formulations of quantum mechanics make sense. They don't make sense to us as metroscopic creatures in a way, but they make sense intrinsically. I don't think there's a contradiction. And then one has to be really careful when you talk about the measurement problem, I think because the measurement problem within quantum mechanics is a bit difficult. I don't think this is the right framework.

So people often say that you have like information exchanged or not really information, but you have a non-local property that happens. Basically, that doesn't follow the speed of light, which it should if it was in agreement with a special theory of relativity. But quantum mechanics is not a relativistic theory. Quantum mechanics is a theory that completely ignored. special relativity. So in principle within quantum mechanics, you could have something that moves faster than the speed of light. There is no velocity limit

there, right? So really the framework to consider these questions would be quantum field theory, which is the only consistent theory that combines a quantum framework with the special theory relativity. And within quantum field theory, there are proven theorems that you can't have any interaction space-like distances, or these are distances that would need travel fast in the speed of light, that have any influence on each other. So that within the framework of QFT is completely consistent. I don't see any unsolved question there. But I don't want to, don't want people to disengage from that because quantum field theory is not the final answer either. It is not

in agreement with general relativity. So if you have a brilliant idea, it might well be that you find the next step forward there. So our super producer of the Into the Impossible podcast, Mr. Stuart Volkow, is just noting that Peter Diamandis is hosting a conference, Abundance 360, and they're all talking about AI and chat GPT and how that's going to revolutionize. We already talked about that. This is just a chance for me to broadcast the fact that Peter's coming on the podcast in a couple weeks, and I'll be on his podcast called Moonshots and Moonbeams or something like that.

a very, very interesting and progressive podcast that I am excited to be going on. So thank you, Stuart. Memes of Destruction. He, another name, I almost chose for one of my kids. Professor Einstein once said, I don't believe this is true. It sounds like something that Abraham Lincoln said. He said, he claims that Einstein said that if he had an hour to solve a problem, I'd spend 55 minutes thinking about the problem and five minutes thinking about the solution. I don't know if that's true, but Lincoln said something like, if you have an hour to cut down the tree, spend 55 minutes sharpening the axe. But I'm going to use a memes of destruction's question as a way to ask about your style. How do you work?

What's it like to be a graduate student in your group and what kind of advice do you give to graduate students on the practice, the craft of being a physicist as they are apprenticing with you? So what kind of, what's your style? How do you work on problems? So personally, so it very much depends on the problem I'm working on. There are some questions I'm working on where I have a pretty good idea on what steps we have to take to get to a solution. These are the problems that in the end are probably the least interesting problems because if I know how to approach them, it's rather straightforward. And it is a good way to solve problems of this kind. if you have, for example, a master student or someone who has never done anything in physics

because you can guide them. I always tell my PhD students, and it's basically an underlying truth of research is that you don't know where you end up. When you start a PhD, most likely, if you look back three, four years later, you won't even recognize what you initially set out to do. That might be less true in experimental physics, whereas you're a bit of clearer picture what you want to build. But in theory, you basically try to nail down a question that you want to answer and then you get to work. And on your way to find an answer to that question,

you often find that there might be much more interesting questions related to that. So I recently read and posted the article by Stephen Weinberg, who gave a recommendation to graduate students, which I can just fully commit to. I think this is completely right. You should start doing research. You should not waste too much time learning the basics as least if you are at the level where you can start a PhD start with a project it's the best thing you can do you will learn on the way and you also said you should go where the masses are so if you're if you are at that level you should not waste your time with something that is too easy if it's too easy then it's not a it's not really a problem worth your time

you should you should go where it's a where there's a difficult problem that many people don't seem to understand and try but they try to make progress there and so sorry I think both these things are right and I communicate them usually to my students as well. Very good. Yeah, so I have that tweet here from you in the name of the late great Stephen Warrenberg. Let me see if I can get that on the screen here. Let's do that. And then we're going to finish up.

Yeah, four golden lessons by late Stephen Weinberg, short read for young and old. So follow, please, Martin on Twitter at Martin M. Bauer on Twitter. And you'll get this and many more viral tweets. He's got the knack for going viral, which is elusive to many of us mortals, mere mortals. So we're going to finish up. I'll take one more question from the audience here, and then we'll move on to the patented final four questions, although it's getting super late there. Very appreciative. We've got to wrap it up.

You've got a young kid at home. I don't want to keep you too long. So I want to just ask one more question about the something that's outside your field, which is going to be the topic of my conversation with Dr. Felix Flicker, who's coming on recording with him tomorrow. So leave your questions for Felix Flickr on Twitter or on YouTube. If you're interested in condensed matter, he's got some viral Royal Institution videos about magnetic monopoles. And he's the first theoretical condensed matter physicist that I've had. on, and he and I will be talking about all sorts of things, including the recent claims of high temperature superconductivity and so forth. So you mentioned the beginning of this conversation

that it was thought that this measurement by Stern and Gerlach would be impossible, that it wouldn't exist. And as you know, the name of this podcast is Into the Impossible. And I asked many people in the last couple of years what they thought was impossible and later turned out to be possible. And by the way, that comes from Sir Arthur C. Clark, who said that the only way of determining the limits of the possible is to go beyond those limits into the impossible. So that's the name of the podcast, and it's kind of my credo here on the project. Is there anything that you might have thought would be impossible when you started your journey as a scientist? But with the benefit of hindsight being 2020, you now have seen to be possible. Is there anything you thought might not be true or even true?

possible to grapple with that has become maybe, if not routine, some part of what we teach to students or otherwise inculcated in your value system as a physicist. So one thing that has happened is the discovery of gravitational waves. I might not have thought that when I started my PhD because I wasn't in the field, but if you go back in history and look at what people thought in the 70s, 80s, 90s, every single step along the way of these kind of experiments, it seemed completely unrealistic to end up where we are and that this is now basically its own field of astronomy. It's its own multi-messenger version of astronomy besides neutrinos and photons.

It's absolutely incredible to me. But let me also mention two things that are impossible yet, that we don't have yet, but they're about to happen. They might happen in the future. And one of them is the, um, is the muon collider. So we will have potentially a muon collide in the US. There is a whole collaboration. now building that wants to work on this. We want some particles that actually decay in a millionths of a second if they are addressed. They're really, really, really short-lived. And to cool them, then accelerate them such that they are long-lived enough with Einstein's time dilation, and then make them collide to do physics with them. Sounds absolutely incredible if you think about

it. But there has been some progress and there needs to be more, but eventually this might happen. It's really, really hard to believe, but this might be possible. And they're not Another thing in another field of physics is the entanglement and the measurement of macroscopic objects, like the quantum properties of macroscopic objects. And there are physicists that are working on entangling things that are as big as a virus, for example. Or things you can even almost see with your bare eye. This was completely unthinkable for decades and might even have implications for quantum gravity. So we might learn, for example, whether the gravitation, how it interacts,

with the quantum properties of these objects. So these two things are absolutely incredible to me, and I really believe that they're about to happen, certainly within our lifetime, but probably earlier than that. Wow. So I can't resist because the name of my second book is Into the Impossible, like the name of the podcast,

and because the foreword was written in combination with my good friend James Altitcher, but also by Barry Barish, who is the winner of the 20, co-winner of the 2017 Nobel Prize. And so Barry wrote the forward, and he also thought this was impossible. But we went ahead and did it. They went ahead and did it, and they continued to do stuff, like proposed to build laser interferometers in space. So just, it's amazing how something can go from being, you know, purely even discarded. I mean, Einstein didn't think we'd ever detect

gravitational lensing, let alone gravitational waves. He did a little tiny calculation. And he showed it to be, you know, curiosity at best. And now we've detected it, and it won a Nobel Prize for Barry and Ray Weiss who have been guest and Kip Thorne, who keeps, he doesn't keep rejecting me. I keep writing him and he keeps saying he's too busy, but he never says, go to hell. So hopes brings eternal that I'll get the Mercurial Kip Thorne as well as the remaining, only remaining member of the Troika. Last question, Martin, that I asked my guest.

Sir Arthur C. Clark, who also said, the only way of determining limits of the possible is going to the impossible. He also said when a elderly but distinguished scientist says that something is possible, he is almost certainly right. But when he or she says something is impossible, they're very likely to be wrong. I'm not calling you elderly, but I'm calling you distinguished. I want to ask you, in that vein, what have you changed your mind about? What have you been wrong about, if anything?

What I've been wrong about? That's a good question because in my field of research, I've been wrong a lot. So basically, I would say almost, so when you think about physics beyond the standard model, for example, right? You're always working about, you're always working on problems that are potentially discoverable. You're not necessarily set out, some people do, obviously, but you're not necessarily set out to propose a new experiment that might be built in 500 years. That's not really your goal. You want to see what can we do now, what can we learn now. And there have been plenty of papers I've written where I thought that maybe this is around the corner,

you can check this at the LHC, and it's heard out not to be right. So I don't really, that I think one should distinguish between proposals like this. And actually, I'm happy to be wrong about those two and what scientists have as like their fundamental belief. This goes back to what we talked about, the Stern-Golag experiment as well. So Stern did the experiment believing that he would not see what, he saw then he wouldn't have gotten an overprice for that experiment then right so he was he was completely convinced that he would disprove that proposal what your personal believe is in a in a in a theory or in a proposal is really irrelevant to some degree it's it's much more important

whether it is scientifically solid proposal that you put forward you can work on it and you can make these proposals and you can be convinced of them or not be convinced of them can hope they be right or not be right that has no bearing at all whether nature follows your instincts and shows whether they are true. So I'm happy to have a podcast to talk about the things that have been wrong. It would be much longer than this one. Well, Professor Martin Bauer, it's a delight to finally get to talk to you. I can't wait to meet you in person in June when I'll be in the UK.

I'll let the audience members know about that, people in the UK who wanted meteorites for me for so long. I will bring a whole pocketful of space schmutz, and I'll give a special chunk to my friend Martin. We meet in person, Martin. Thank you so much. Team Into the Impossible, stick around the rest of this year is shaping up to be just phenomenal. You're not going to believe some of the guests who are coming on

and some of the opportunities I'm going to have to go on other people's podcasts. So stay tuned for that. And it's really because of you guys, the audience and the great guests that I get like Martin. And it's just, it's really overwhelming to have over 100,000,000, thousand people now following us and participating because they can't really do it without you guys. So when I post something on Twitter, I post something on YouTube, please, the best thing you can do, first of all, give a thumbs up if you like this interview, write a comment if you like this interview. The algorithm is still governed by AI.

So that's one of the best ways to engage, engage with Martin, engage with all my guests, ask them questions, and let them know what you thought of their appearance. And hopefully we'll use that to get even more guest of the caliber that we had today. I can't thank Martin enough for his time and wisdom. I look forward to many of these. As I said, maybe we'll do one in person in the UK. That would be super fun. I'll get you out here in San Diego.

I'd love to host you here. And we have some rainy weather lately, so it'll make you feel at home. You will. Thank you very much, Brian. It was all to be on. Congratulations to the 100,000. It's Biden chief, and I told you. Thank you so much.

I hope it keeps up. Any sufficiently advanced technology is indistinguishable. from magic. Thanks for listening to Into the Impossible. Keep in touch by signing up from Professor Kitting's Monday magic email at Briankeeney.com slash list. And if you have a dot edu domain, we'll send you a particle from the belly of an exploding star in the form of an authentic meteorite fragment. Please help make the show better by filling our listener's survey linked to in the show notes. Thanks to all our viewers and listeners for helping us break the 100,000 and subscribe America on YouTube.

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