How Strange Anomalies Lead to World-Changing Discoveries with Harry Cliff

Please join my mailing list here 👉 https://briankeating.com/list to win a meteorite 💥 If we look back at the history of physics, many of the biggest discoveries were triggered by strange anomalies that sparked curiosity in the minds of great scientists. But how do anomalies drive scientific discovery? What are some anomalies that are currently reshaping our understanding of the universe? And are we on the brink of discovering new physics? Here today to shine a light on this fascinating topic is none other than Harry Cliff. Harry is an experimental physicist at CERN and renowned science communicator who recently published “Space Oddities: The Mysterious Anomalies Challenging Our Understanding of the Universe.” In it, he examines a catalog of weird phenomena that simply can’t be explained by our long-established theories of the universe. Are these anomalies just accidents, or are they pointing us to new discoveries like they did many times in the past? Find out in our exciting conversation! — Key Takeaways: 00:00 Intro 00:34 Judging a book by its cover 02:25 From anomalies to discoveries 05:03 Understanding sigma and confidence in science 13:30 Muon g-2 and its implications 19:18 Neutrinos and the search for new physics 21:58 Hubble tension and the future of cosmology 24:58 LHCb experiment 33:37 The matter-antimatter asymmetry problem 37:39 Harry’s gut feeling on dark matter 42:10 The role of anomalies in scientific discovery 46:10 Black hole information paradox 46:57 The importance of skepticism 49:13 Outro — Additional resources: ➡️ Learn more about Harry Cliff: 💻 Website: https://www.harrycliff.co.uk/ 📚 Space Oddities on Amazon: https://a.co/d/eV4xhAv ➡️ Follow me on your fav platforms: ✖️ Twitter: https://twitter.com/DrBrianKeating 🔔 YouTube: https://www.youtube.com/DrBrianKeating?sub_confirmation=1 📝 Join my mailing list: https://briankeating.com/list ✍️ Check out my blog: https://briankeating.com/cosmic-musings/ 🎙️ Follow my podcast: https://briankeating.com/podcast — Into the Impossible with Brian Keating is a podcast dedicated to all those who want to explore the universe within and beyond the known. Make sure to follow/subscribe so you never miss an episode! Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  The people that have the instinct to follow those little clues that often make the biggest discoveries, whether that's Penzias and Wilson and their microwave buzz, or it's Rutherford and his blurry alpha particles. It's those little strange things that you really need to pay attention to. It's very rare that discovery reveals itself in a big flash in the way that maybe we've imagined through the kind of popular tellings of the history of science.

• 0:20Brian Keating?

  Harry Cliff, welcome back to your second appearance on the Into the Impossible podcast. So good to see you.

• 0:24Speaker 00

  Great to be back, Brian.

• 0:26Brian Keating?

  And you've written a book about David Bowie this time, Space Oddities.

• 0:29Speaker 00

  Yeah.

• 0:32Brian Keating?

  So I was very pleased I didn't have to pay for the advertisements, but there's two of my experiments mentioned in this wonderful new book, new in paperback, I should say. I listened to it, I read the hard copy and I bought the Audible, but now the paperback is out. So double congratulations there. As is our want, I want you to take us through the cover, the title, the artwork, but also the subtitle. I always love subtitles because that's the one thing that the author has some control over. So take it away. How did you come up with this very man who fell to earth type cover?

• 1:02Speaker 00

  I knew I wanted to write a book about anomalies, but it was trying to come up with a title that was going to grab people. And I was basically going through a conversation with my US editor, Yaniv Soha, who was at Double Day then. Basically it splurged a list of just random ideas at him, including, and Space Oddities was one of them. Because you know, it's a bit of a fudge because a lot of the anomalies in the book are really about particle physics. And there's a couple that are astronomical, cosmological anomalies. But he was like, it's got to be that one. That's got to be the one. So I was like, okay, well, I guess we can live with the fact this only sort of addresses about half the stories in the book. So that's where Space Oddities, David Bowie is like my favorite musician of all time. So it works from that perspective. In terms of the subtitle, which is the mysterious anomalies challenging our understanding of the universe. I mean, I think that sort of speaks for itself really.

• 1:47Speaker 00

  It's basically about these strange observations, results that we'd been seeing back when I was writing the book, that were looking, several of them looking like they might be the sign of something beyond our two standard models of particle physics and cosmology. As for the artwork, I mean, this was come up with by, by the publisher, the US publisher Double Day. This is actually a UK cover, but the UK edition just takes the same image. So I think they were just trying to come up with some. Thing that was unusual. So they've got this kind of weird sort of infinity slash Mobius strip symbol on the cover with a little earth and a moon next to it. So I guess that kind of says space, but also there's something odd. And I quite like the yellow. I guess it means it jumps out on the bookshelf for sure. You can't miss it.

• 2:24Brian Keating?

  So when I read the book and I think about these kind of anomalies, it's really the anomalies that provide our deepest insights. People think of symmetry and beauty, our friend Brian Greene, kind of elegance and beauty. But actually, the universe is pretty hideous and thankfully so. As you point out in the book, if we had a perfect symmetry between, say, matter and antimatter, well, we wouldn't be we, right? So isn't it true that as Leonard Cohen said, that it's really the anomalies, the cracks, as he called them. So a famous song called Anthem, "Ring the bells that silicon ring, forget your perfect offering." There's a crack, a crack in everything. That's how the light gets in. So isn't it true that most of what we know about physics comes from the things that aren't perfect, the cracks, the imperfections?

• 3:08Speaker 00

  I think that is true. And if you look, you can look back in the history of physics, and so many of the biggest discoveries began with something that was just a bit weird, that people didn't really understand. I mean, one example I don't even give in the book is actually the very famous discovery that took place more than a hundred years ago of the atomic nucleus. That discovery came from Ernest Rutherford, who was a sort of leading nuclear physicist of the era, and Hans Geiger, working in Manchester. And they basically had this, they were building an early version of the Geiger counter. They had this tube of gas and they were firing alpha particles through it, these particles that come out of radioactive atoms. And what they expected was that these particles were from a very sharp dot on a photographic plate at the end of this long tube of gas, because they're like bullets. They should go through the gas

• 3:51Speaker 00

  without getting deflected. And what they saw instead was this kind of like fuzzy image, this kind of like, it was a bit smeary. And Rutherford, he had this amazing ability to go, oh, that's just, that's a bit strange. And that kind of little clue led through a series of further experiments and steps to the discovery that the atom, the picture of the atom that we had in the early 20th century was wrong, and that it wasn't this kind of diffuse thing that Thomson had imagined, but had this nucleus in the middle with electrons going around the outside. That's just one example. At the other end, I mean, probably, I think this is what the story I've mentioned at the end of the book. Probably the most momentous discovery of the 20th century, which is the cosmic microwave background, which your listeners are well familiar with, which is the the real clinching evidence that the Big Bang really did happen and persuaded most of the

• 4:36Speaker 00

  remaining doubters, not Fred Hoyle, but most of the others. And that again, came from this noise in an instrument. It was this irritating buzz that was thought at one point to be pigeon droppings in their in their radio antenna. And that turns out, again, it's following that that little clue. And that leads you to some incredible revelation. You discover something completely new and it shifts your view of the world. So I think you can find these kinds of strange anomalies and underpinning so much of what we know in both physics and cosmology and astronomy.

• 5:03Brian Keating?

  It's really amazing how these commonalities between the very small scale physics, particle physics, accelerator physics, and anomalies there connect with the largest anomalies in the universe, literally the whole universe. My favorite story, of course, bicep two and the subject of my first book, Losing the Nobel Prize, has the bicep story. It's featured heavily in your book. But most of the anomalies, like most of the big claims, often turn out not to be confirmed. And I think it would be good for my audience, who's not only the most brilliant audience in the known multiverse, but to have a little bit of a glimpse into what the technical details of a non-anomaly, a discovery, if you will. You talk a lot about sigma, confidence. We talk about that, not in the context of charisma.

• 5:48Brian Keating?

  But tell us, what is sigma? What is confidence? What are these things? And how should a lay person kind of interpret whether or not something is a true discovery if they hear about some fascinating discovery on page one of the New York Times like bicep, and then they never find out until many years later, oh, actually, that wasn't confirmed. And so many people are left with the impression these things are still on the hunt. So tell us, what is sigma? What's confidence? What do they mean to scientists and to laypeople?

• 6:12Speaker 00

  Broadly speaking, when we talk about sigma, what we're really talking about is uncertainty. So any scientific measurement or observation comes with some uncertainty. And that uncertainty can be to do with the amount of data you have. So if I want to like, know what's the the average height of a of a man in the in the UK, if I take two men and I measure their heights, I'm going to get a pretty inaccurate estimate of the average height of all men. If I want to absolutely the right answer, I'd have to go and get all thirty five million men and measure all their heights. But the more men we measure, the more precise our our average value gets. And the uncertainty on that average value gets smaller and smaller. And it's the same if we're measuring the mass of a fundamental particle. The more of these fundamental particles we produce, the more times we measure the mass, the more precise our measurement gets.

• 6:56Speaker 00

  You have this sort of statistical uncertainty, which is an expression of how well we think we know this thing, within some range, basically. The other side of it, you also have a systematic uncertainty, sort of a much more of a black art. But they're an attempt to express the things you don't understand about your experiment. Do we really know the resolution of our telescope as well as we think? What happens if we make a different assumption? What does that do to our results? So these things come together basically to give us a sort of a range which we say, okay, we think the value is here, but there's this range around that value which it could fall within with a pretty high degree of likelihood. So one sigma, what we call the sort of one sigma band is where basically if you did the experiment a hundred times, sixty eight times it would fall, the result would fall within that band, broadly speaking.

• 7:40Speaker 00

  So that's what we mean by sigma. And then in in physics, and it well, I think it began in particle physics, and it's now spread to other areas of physics. We have this sort of slightly arbitrary scale of how we define whether a measurement is in tension with, say, your theoretical prediction. So let's say you have your theory, it could be your standard cosmological model, and it predicts some quantity, say, the Hubble constant, how fast space is expanding. You go and measure the Hubble constant, then what you want to do is compare your experimental measurement to your theoretical prediction. And you look how many units of uncertainty away are these two observations? And if it's within one or two sigma, people say, oh, that's fine. That's basically agreement, you know, that's kind of what you'd expect. When it gets to three sigma, around three sigma, there's a kind of

• 8:24Speaker 00

  one in a thousand ish chance that you would get two values deviate by that much, by random chance, just by dumb luck. So in other words, if you did the experiment a thousand times, only one of them would end up in that much tension just by statistics. So at three sigma, people is completely arbitrary, but people call that evidence. When we say we have a three sigma tension, that is the evidence that there may be something interesting going on, but we can't really be sure. And and the reason we say, well, three sigma is just evidence, but it's not confirmed, is that we make loads and loads of measurements, particularly, say, at the Large Hadron Collider, where I'm where I do my research. We put out, I mean, we put out thousands of papers in the last 10 years.

• 9:05Speaker 00

  So if you make thousands of measurements, then some of them are going to be in three sigma tension just by pure statistics, regardless of whether you've made a mistake in your experiment or not. So that's why we don't trust three sigma results. They're intriguing. People might go, okay, well, three sigma, we're going to look into this. We're going to investigate this a bit more, but no one's going to book a flight to Stockholm for a three sigma result. Then we get to five sigma, which has now become this sort of gold standard. If you get to five sigma tension, that is what we call now an observation or a discovery. So when the Higgs boson was discovered, for example, in 2012, the thing that convinced everyone was both you had these two experiments, two detectors at the Large Hadron Collider, both saw a new particle at five sigma, so five sigma above the background, basically.

• 9:48Speaker 00

  And at five sigma, you're talking parts in a million chance of it being a statistical fluke. While we make thousands of measurements, we don't make millions. So if you have a thing that's parts in a million, it's there's something happening. And and hopefully the something is new physics. It could also sometimes be some systematic that you've just missed. That also can happen. But that's the kind of the the thresholds that we use, three sigma evidence, five sigma of discovery, barring the fact you haven't made any mistakes anywhere.

• 10:15Brian Keating?

  Many of the anomalies that you talk about and describe in the book are later shown not to be anomalies. And you speak of that being disappointing. It's always disappointing, even though we know going into it, the odds of the standard model, I think, Nima Akhane-Hamed, who promised to come on the podcast four years ago, but still has not gotten pinned down yet. But anyway, he said the standard model is stronger than diamond. It's very hard to break the standard model. And he's referring to the standard model of particle physics. But now we're talking about astrophysics, cosmology, and the book ends with a description of Hubble tension. Do we give more slack, as it were, to cosmology or particle physics compared? To particle physics and that we're willing to accept things that seem to be five sigma.

• 10:58Brian Keating?

  And then they literally turn to dust in the case of bicep two. Do we give more kind of leeway to cosmology astrophysics than we do to particle physics? And if so, why do you think that is? It seems like we're very strict, harsh judges of particle physics and maybe give a little bit more leeway to the astrophysicist.

• 11:15Speaker 00

  Yeah, I don't know about if I put it that way exactly. I mean, certainly from talking, actually, I'm not an astrophysicist or a cosmologist, but like speaking to you and your colleagues. Like my sense is that people are more willing to take anomalies seriously in cosmology. Because the Lambda CDM model, the standard model of cosmology, the two things that are in the name of it, Lambda, dark energy, CDM, cold dark matter, we don't know what they are, right? We have very little information about what these things are. So you have this model, which is based on general relativity, which I think most people would believe is pretty solid. But the actual ingredients of the theory, the energies and forms of matter are completely unknown. So it's really, it wouldn't be that surprising if Lambda CDM is wrong. If dark matter interacts with itself, for example, or if there are multiple types of dark matter,

• 11:59Speaker 00

  or if dark energy is dynamic, then you know that the theory needs modification. So I think it's easier to believe that you may be seeing something that does challenge your standard model in cosmology. In particle physics, though, you've got this model that's been around for half a century and this wealth of data, like high precision experimental data, a whole range of international experiments that, you know, the standard model agrees with beautifully. So if you find an anomaly, it has to, and you want it to be new physics. You've got to somehow introduce new physics in a way that doesn't break everything else. Cause your new theory, whatever it is, your extension of the standard model, still has to have all the same successes of the standard, as the standard model and explain your anomaly.

• 12:40Speaker 00

  So in those case, I think people probably say, well, the prior is the standard model is so good and so precise. And it works in so many different regimes and different particles, different sorts of processes, that you really have to do the work to convince anyone that an anomaly is worth taking seriously. And I think it's fair to say that there are no particle physics anomalies on the offer at the moment that reach that threshold. For a while, I think there was a sense we were getting close. With some of B quark anomalies that maybe we'll talk about in a bit. But as we'll see, that's now in a more ambiguous state again. We don't really know quite what's happening there. There was a tweet that I think it was John Butterworth or another of my colleagues put out when there was a load of news around some of these B anomalies that were coming out of the LHC. And it was a picture of a huge ship labelled standard model.

• 13:23Speaker 00

  And like a little tiny boat that it was crashing into called the anomaly. And I think that's a nice way of thinking about what, how it is in particle physics.

• 13:30Brian Keating?

  Yeah, let's go through some of the, the particle physics anomalies that you talk about. You start with muon G minus two, which was not only heralded as some abstruse corrections at the 12th decimal place to lattice QCD, but actually is heralding the existence of a fifth force. So what do you make of these kind of overreaching statements? I mean, even though the experimental results seem to be quite strong, it didn't hold up to scrutiny. And I think the challenge is how do we actually get the word back out to the public that these things are disconfirmed or ambiguous? Once the kind of horse is out of the barn, so to speak. So talk about the status of G minus two, why that's so important. And what would it mean to really have a fifth force?

• 14:14Brian Keating?

  What would that do to physics, even to the philosophy of science?

• 14:17Speaker 00

  Just to explain what G minus two is for the benefit of anyone who doesn't know. There's this particle called the muon, which is a heavy version of the electron. Doesn't exist normally, but we can create it in experiments. And it has, it behaves like a little bar magnet. So the muon spins just like an electron. And because it's charged, that angular momentum comes with an associated magnetic, magnetic field. And the strength of the magnetism of the muon depends not just on the muon, but on the contents of the vacuum around it. So in particle physics, the vacuum is not empty. It's full of these things called quantum fields. And these quantum fields interact with the muon. And the, so you have to, in order to know the magnetism of the muon, you have to calculate with the standard model of particle physics, the influence of all these different fields.

• 15:01Speaker 00

  And if you do that, you get a very precise number to 12 decimal places or whatever it is now. And the idea, and what had been seen more than 20 years ago was this tension between a very precise experimental measurement of this little bar magnet that the muon. carries around with it and the the standard model prediction at the time. As a little sort of forewarning, Chris told me that when he was a student, there was actually this moment when they first started running the original experiment in Brookhaven, where very quickly they were in three sigma tension with the standard model. And what they discovered was that the theory prediction, there was a sign error in their calculation. So somewhere one of the terms, someone had flipped the plus for a minus, and that created the illusion of this tension. So once they fixed that, it went away. They took more data and but I think it was around two thousand and one.

• 15:46Speaker 00

  They were back in three sigma tension again, but they couldn't really get any more meaningful data out of the experiment. So this anomaly just sat there at three sigma for years and years. And Chris and his colleagues then went on to redesign a new version of the experiment, basically taking some of the original equipment, this big superconducting ring that was used at Brookhaven and shipping it to Fermilab, rebuilding the whole experiment. In the meantime, the theoretical technology is evolving. So this calculation of this magnetism is incredibly difficult. There are all these different terms in the the calculation that have to be done. And the really hard bit is basically the way that the muon interacts with quarks and gluons in the vacuum. So you have this sort of like, you can think of it as this virtual haze

• 16:29Speaker 00

  of quarks and gluons that follows the muon around. And the theory of quarks and gluons, QCD, quantum chromodynamics, is famously impossible, very difficult to calculate. And so there was this kind of clever method where rather than trying to work out how quarks and gluons influence the muon, they take experimental data where you collide electrons and positrons to make quarks and gluons, which is basically the same process turned on its side. And you translate that data and plug it into your theory prediction and you and you get a very precise prediction for the muons magnetism by doing this. So the first time that the new experiment unblinded, the real question was, is the new measurement with a new machine

• 17:09Speaker 00

  going to line up with the old experimental measurement, or is it going to line up with the theory, the new theory prediction, which is even more precise now? And it lands bang on top of the old Brookhaven measurement and everyone's really happy. You combine the results, you get over four sigma tension. This is starting to look really serious and people think, okay. Well, in a year, when we've got more data, this will be five sigma and we can all, we can declare the discovery of something new. Because what that's really saying, this anomaly is saying that there's something else in the vacuum that is not in our prediction, that is altering the muon's properties. And one, you mentioned the fifth force. So one possibility is there is a new gauge fields or some new kind of vector field like the photon or the the Z boson in the vacuum. And that is altering the properties of muon. So, I mean, but you can basically come up with lots of explanations.

• 17:53Speaker 00

  It could be supersymmetry, extra forces, dark forces that are related to dark energy. But basically what it's telling you is if this is real, there is something new and the standard model is missing something, which is very exciting. But then the big twist is just after, actually the same day that the Fermilab experiment released their first result from the first year of data taking. After a decade of laboriously building this high precision piece of kit. This other theory group from, called the BMW collaboration in Germany, come up with a new calculation of the muon's magnetism. Based not on this kind of experimental data, but this technique called lattice QCD, which is basically a way of solving the equations of quantum chromodynamics using supercomputers in effect.

• 18:37Speaker 00

  And when they do this, they get a result, there is much better agreement with the experimental measurement. So if you believe the standard theory prediction, you may be discovering new physics. If you believe this new approach, then there's nothing to see, basically. And what has happened subsequently, muon G minus two experiments taken more data. Their result is now well over five sigma with the old prediction. But it now looks like this new lattice QCD technique is actually the correct one. And people are more confident it's the right approach. So the anomaly has gone from five sigma or more to one sigma, i.e. no anomaly basically anymore. And I think the thing people are still trying to unpick is what went wrong with the original theory calculation. So this is an unusual example in some ways.

• 19:19Speaker 00

  It's like it's anomaly driven by a theoretical miscalculation, not by an experiment. So you have to feel a little bit sorry for the experimentalists, I think, because they've devoted. Yeah, a decade or more of their lives to building this incredible piece of kit. And it really is like a giant Swiss watch, this thing, really high precision. They make this beautiful, pristine measurement. And then it turns out the whole motivation for the experiment was actually, the theory was off. But I suppose what I would say, just to sum it all up, although that's maybe disappointing from New Physics's point of view, what it does do, actually, we've learned a huge amount about how to calculate with quantum chromodynamics as a result. So that's one of the points I make in the book. Even when anomaly doesn't lead to some big breakthrough in fundamental breakthrough, it often really sharpens your scientific tools. So we now have a much better understanding of how to do these sorts of calculations

• 20:04Speaker 00

  and how to build these precision experiments, which sort of lays the foundation for future discoveries. So it may be, maybe this time, no new physics, but this may be a key ingredient to the next discovery as and when it comes. So it's not all doom and gloom.

• 20:16Brian Keating?

  I ask my audience, as I often do, on Twitter, X, on YouTube, on my YouTube community or post tab, for some questions for you. I got a bunch and some of them will lead into a segue into more questions from my favorite guest, which is me, to ask you for your opinion about the more sociology of physics and science in general, but we'll get to that in a second. So Cameron Bannock asks, how likely are neutrinos to lead to new physics?

• 20:42Speaker 00

  Well, I think it's really hard to say. I mean, when you say like, before you've done the measurement, is it going to lead to new physics? I wouldn't want to place a bet, but there's a lot about neutrinos we don't understand. So they're definitely worth investigating. And the more places we look, the more likely we are to see something. So, I mean, one of the things that I think is really interesting in the future experiments, neutrinos that are coming up. So you have in the States, June, which is being built at the moment, this huge new neutrino experiment between Fermilab and a deep mine out west. And one of the things that June is going to try and do is measure whether neutrinos violate matter/antimatter asymmetry. So what we technically call charge parity symmetry. And there's some weak evidence from a Japanese experiment called T2K that they do.

• 21:26Speaker 00

  And if they do, that could be the explanation or could be part of the explanation as to why the physical universe exists. You've alluded to it at the beginning of the conversation, that the fact that there isn't this perfect symmetry between matter and antimatter. Allowed the universe as we know it to come into existence because without it, it would all be annihilated in the big bang and there'd be nothing. That's what I'm really interested to see. When June reports its results, does it see the neutrinos respect matter antimatter asymmetry or not? And if they don't, that may be the clue to solving one of these, this, one of the biggest mysteries actually in, in fundamental physics, which is how we got here.

• 21:58Brian Keating?

  And my question is a follow up to Cameron's is we, as you point out at the end of the book with discussion about Simons Observatory, you mentioned in the context of your encounters with your friend and my friend, Joe Dunkley, is now the spokesperson of the Simons Observatory, that instruments like ACT and Simons Observatory in particular are gearing up to measure and help to resolve, perhaps to resolve the tension known as the Hubble tension. Although I say it's much cheaper than the $200 million Simons Observatory to just hire a team of therapists to counsel us cosmologists. Let's say we are successful, not in that endeavor, but we have another significant science goal with Simons Observatory in addition to looking for inflationary gravitational waves, so called B mode polarization, which you discussed, but also measure the mass and relativistic energy density budget

• 22:43Brian Keating?

  of neutrinos or, you know, relativistic particles. I want to ask you a question, do a hypothetical, we are successful, quote unquote, or our competitors, it doesn't matter. And a cosmology experiment like the CMB experiment measures the mass of, the sum of neutrino masses. That would, if I'm not mistaken, mark the first time that a mass of an elementary particle is measured not on the earth. It would be measured cosmologically, it would be measured astrophysically. It would be the first measurement of the 17 elementary particles having to do with their three fungible characteristics, mass, spin and charge, that was not measured in a lab like you operated. Would your colleagues believe it? Let's say we come up, it's three, four sigma, we measure the hierarchy, whether it's inverted

• 23:26Brian Keating?

  or standard. What would be the reaction sociologically speaking? Would you guys believe it? Or does it really need to do what's called a direct detection before a honest to goodness, practicing master of particle physics like you and your colleagues would believe it?

• 23:40Speaker 00

  That's a very good question. I mean, I should say, I'm not a neutrino physicist. You probably have to ask a real neutrino expert to get their view. I mean, I don't really know the details of how these measurements are done. So I guess the question would be, to what assumptions is it based on? Which cosmological model do you have to assume? What are you assuming about dark energy or dark matter? So I guess that's where the uncertainty may come in. If it's built on some model that is not regarded as being totally solid, then I suspect people probably would want to see a laboratory experiment confirm the result in one way or another. And I suppose it also depends a bit. In particle physics, if it had just been one detector that had discovered the Higgs boson, I don't think people would necessarily have been totally convinced. You would, you really want, you always want in it with anything, some confirmation externally.

• 24:24Speaker 00

  So whether that comes from another astronomical experiment, observation, or if it has to come from particle physics, I don't know. But yeah, I think, on the other hand, particle physics do take a lot of what, you know, you guys say to us very seriously. There are all these dark matter experiments and a lot of my colleagues at the LHC spend their lives looking for dark matter. And that is based not on any evidence from laboratories here on earth. It's purely astronomical in nature and that drives a lot of what we do. So I think, I think for sure, people take what cosmologists and astrophysicists take seriously. I guess the question is, what are the details of the measurement?

• 24:58Brian Keating?

  Getting back to some of the anomalies that you speak about in the book, the notion that physics may be hiding in plain sight, so to speak, and it will take new and better microscopes, if you will, to really unravel the detective, the mystery story. I think there's no better example than your field of research, which is LHCb. So talk about what is LHCb? What has been the history of the last over a decade? I mean, I'm only familiar with the previous interview that you did on the podcast. But talk about this and these different measurements and the level of conflict or tension, as we said before, where these anomalies went back and forth, whipsawing between new physics and just consistency with the standard model. So talk about that effort as one of the key players in this endeavor.

• 25:41Speaker 00

  Yeah, so well, LHCB, it's one of the four experiments on the Large Hadron Collider. So you have this big 27 kilometer ring, four places where the particles collide, four big detectors. And LHCB is one of them. And LHCB is a specialized detector. So what the B stands for is beauty, which is a name for one of the six quarks, also called the bottom quark, more usually called the bottom quark. I think I probably made this joke last time as well. But the reason it's beauty for us is we'd rather be beauty physicists than bottom physicists. So we call it the beauty quark. And the experiment, really what it does is it produces, you know, the Large Hadron Collider produces billions of these beauty quarks every year. And the experiment is designed specifically to capture as many as possible, record their properties.

• 26:20Speaker 00

  And the reason these things broadly speaking are interesting is that these bottom quarks, beauty quarks are unstable. So you make one of these things, it decays in about one and a half trillionths of a second. And because it's the fifth heaviest of the quarks, it can decay into a lot of different particles in the standard model. So there's a very rich phenomenology associated with these things. And the way they decay, generally how a particle decays, a fundamental particle decays in the standard model, is it involves the weak force. So the bottom quark will like radiate something called a W boson, and it will turn into a charm quark. And then that charm quark will decay into a down quark. And you basically end up with ordinary matter at the end, which, you know, which is the stuff that hits your detector, broadly speaking.

• 27:03Speaker 00

  And what we saw at LHCB, we've been looking at a series of different, what we call rare decays. So there are lots of different ways these bottom quarks can decay. And there are some of these processes that are very suppressed in the standard model. So they are predicted to happen less often than one in a million, so one in a million or less. And some of them parts in a billion or fewer. And the reason these rare decays are interesting, because they're so, basically the reason they're suppressed is for them to happen, you need a complicated combination of the weak force and the electromagnetic force and top quarks and all kinds of stuff to get together in the right way to mediate the decay. And that's what makes them rare. The analogy is a bit like you're trying to get between two subway stations on a subway network that don't have a direct connection. You have to change at multiple stations and it just becomes very complicated and no one can be bothered to make the journey.

• 27:48Speaker 00

  But if there's new physics, so let's say there's some new quantum field in nature, some fifth force or something else, that is a bit like a new metro line, a new subway line, connecting those two stations directly. And so that can provide a new route for the decay to happen. And it can change the rate the decay happens, it can change some of the properties of the decay, like what directions do the particles go in, what the energies, the energy spectrum, that kind of stuff. So broadly speaking, you try and get a load of these rare decays, you try and observe them, you measure their properties and then you compare to your standard model prediction. And if you see a deviation, that could be new physics. So that's the kind of game, really. It's a very similar thing to the muon G minus two experiment, but just at higher energy in a collider, really, in many ways.

• 28:29Speaker 00

  What we started to see back in 2014, actually, was that, first of all, if you look at the angles that the particles were coming out from these decays at, they didn't match the predictions of the standard model. And as the story has evolved, this is now over three sigma tension. And the latest measurements seem to confirm this as well. So that, these angular anomalies, they are still there. The thing that got everyone really excited is there was a series of measurements testing this principle of the standard model called lepton universality, which is basically the idea that the forces in the standard model interact with the charged leptons with the same strength. So the leptons are the electron, the muon and the tau, these three charged particles that we find in nature.

• 29:13Speaker 00

  So what we've been doing is comparing how often one of these rare decays produces electrons and how often it produces muons and comparing the two. And you basically get a ratio and then the standard model of that ratio is one. They happen at the same rate. And what we've been seeing was this ratio, muons over electrons, was actually smaller than one. It was point seven, point eight or so. And the reason this was so exciting is because the devil, again, with these measurements is often in the theory. And these particles, these quarks, they're quarks, they interact with gluons and QCD is involved. And you can't, it's very hard to calculate QCD. So any measurement you make, the theoretical prediction has quite a big uncertainty because we don't, because it's difficult to calculate stuff in QCD.

• 29:56Speaker 00

  But if you take two processes that are basically the same and all you're doing is flipping an electron from muon, the QCD bit is the same in both of them and it cancels out. So your theory uncertainty disappears, basically. So your theory is really well known. The theory says this ratio is one, no ifs, no buts. There's no possible effects in the standard model that we could miss. We know this thing must be one. So if it's not one in your experiment, you know damn well that you're seeing new physics. All the experiment is wrong. So what we saw, you know, a series of these measurements of lepton testing lepton universality, my colleagues made several, I made one myself with a student, which came out in 2000, what was it, 2020, 2021 now, and they were all down, they were all below

• 30:37Speaker 00

  one, all of them. And combined with these annual anomalies and also anomalies in the rates of these decays, so basically how often they happened, the theory community got really pretty excited because what they found was all of these different anomalies in different areas of particle physics, there were some other ones as well that actually came from other experiments, Bell and Baba, these B experiments in Japan and the US, you bring all these together and you can introduce a fairly sort of modest extension of the standard model and explain all of them at once without breaking anything else anywhere else. And what got people really excited is often these theories hinted at some deeper structure beneath the standard model. In other words, there's this, there's this mystery which we still don't have an answer to, which is in the standard model, the matter particles

• 31:21Speaker 00

  come in three generations or families, they're often called. The first generation is the stuff we're made from, electrons and up and down quarks. Then there are the heavier versions which include the muon and the tau and the top quark and all this kind of stuff. And we don't know why they exist. It's a bit like zoology. We found these things in nature, we arranged them in a table, or maybe it's more like the periodic table of the elements, like you see these repeating patterns, but we don't understand where the patterns come from. The way that the patterns in the periodic table are explained by atomic structure, the hope was that these new theories would explain the structure of the standard model in terms of some deeper theory. And so that's what everyone got very excited about. But then what happened basically was in sort of 2022, my colleagues made another of these lepton universality measurements, reanalyzing some of the same data and got a different

• 32:06Speaker 00

  answer. And this was basically a clue that once it unraveled, that turned out there was a mistake in the, in these lepton universality tests. And so once that was corrected, those sets of anomalies disappeared and they've basically now gone. But we still left with these other anomalies, the other bits of the picture, and they are still there. So we are in this very ambiguous state now where we've already got egg on our faces in some ways, these anomalies that were the ones that were the most promising have disappeared. But these other anomalies that are much more affected by these QCD effects, but look experimentally much more solid are still there. And again, it's a bit like the muon G minus two situation. It's like, are these remaining anomalies just QCD and we need to understand QCD better? Yeah, it could be an experimental measurement problem. We don't think so this

• 32:51Speaker 00

  time. Or is it actually still new physics? That's the journey we're still on trying to disentangle these things. So it's been a it's been a bit of a roller coaster. It's great height of excitement. I have to say, you're talking about the sort of the way these things are publicized. The actual messaging from the experiment was very cautious. We had it was actually made fun of on social media at the time that we had this phrase that we put out, which was we're cautiously excited. And so we were always like very cognizant of the fact that this could turn out to be nothing. But nonetheless, when you're in the middle of it, and you feel like this could be something really big, you can't help but get a little bit excited. And having been through the disappointment of and the embarrassment and the is, I think a lot of people found it very difficult, actually, the unraveling of this. And now begin to pick yourself up and say, okay, we're going to carry on. We've still got these other things to investigate. It's

• 33:34Speaker 00

  been an interesting lesson in science, I think, for me and my colleagues, for sure.

• 33:37Brian Keating?

  And so going back to your previous book, How to Make an Apple Pie From Scratch, shout out to the great Carl Sagan, I got a finger puppet of him, was a discussion in that book, which one of my viewers is asking, his name is LV Gamer Cats, which I recommend to you as a choice for an upcoming child's name, perhaps. Gamer Cats makes a great name for a baby. He says, you described how a hypothetical spelleron might explain the matter antimatter asymmetry that we started off the podcast talking about. Is that still your preferred explanation?

• 34:09Speaker 00

  The spellerons are, they're not particles, but they are features of the standard model. And they are basically a kind of like a, in the standard model, we have these forces, the weak force in particular, which is generated by this thing called the Higgs mechanism. So we have this thing called the Higgs field, and we have the W and the Z fields, which are the the force fields of the weak interaction. And a spelleron is kind of a coherent motion of all of these fields moving together in unison in some way. But unlike a particle is like a vibration in one of these fields. You can think of a particle like a ripple on a pond. There's a ripple in one of these fields. So like a photon is a ripple in the electromagnetic field. A spelleron isn't a vibration in that way. It's this kind of coherent motion. They come out of the standard model. They're just part of the

• 34:53Speaker 00

  equations of the standard model, essentially. So they're very weird objects. They Haven't existed in the universe since the very earliest moments of the big bang. You need energy densities and temperatures that existed about a trillionth of a second after the big bang to make these falons. But in the very early universe, according to the standard model, they would have been abundant. There would have been, there would have been a lot of them around. And they have this very weird ability, unlike anything in the standard model, they can make more particles than antiparticles. So they're kind of these weird machines that you feed particles in and antiparticles come out or vice versa. So they're, they're in principle, the standard model has this ability to break antimatter, antimatter symmetry in the early universe.

• 35:35Speaker 00

  Through these falons and through other processes as well. They're almost certainly involved in some way in how matter was made during the big bang. But there are different versions of this story. So the two I talk about in the book, there's one called, this is a terrible terminology, but it's called electro weak baryogenesis. So this is basically the production of baryons, i.e. protons and neutrons during what's called the electro weak phase transition. So this is a transition around a trillionth of a second after the big bang, when the Higgs field switched on for the first time. And the forces as we know them took their current form. And it's a sort of phase transition in much the same way as like water in a kettle boiling is a phase transition.

• 36:18Speaker 00

  And at this phase transition, in certain models with these falons involved, you can make matter over antimatter. The problem is for that to work, you need new physics at the same scales that we're probing at the Large Hadron Collider. And we're not seeing it at the moment anyway. So that looks kind of disfavored. Another option, which is probably more popular is something called leptogenesis, which is associated with neutrinos and connected to what we were talking about before with June. This idea that basically the neutrinos have these very heavy partners, sterile neutrinos with very large masses. That you have to go back even further in the history of the universe to find these things. They would have existed at what's called like the grand unified scale. So this is an energy scale just below the Planck scale in like, you know, the first tiny fraction of a second.

• 37:03Speaker 00

  And there are processes there where these leptons, these very heavy leptons decay preferentially. Matter versus antimatter and then the Svaleron's can mix everything up and at the end of it all, you get matter left over. So there are these two rival processes and there's others as well. The problem is that with barrier genesis, we can test it because the energy scales are what we can probe at the LHC, but we don't find the evidence for it. With leptogenesis, the energy scales are the gut scale, which we can't access experimentally. So it's tricky to say one way or another, but as to the question about Svaleron's, they probably played a role. But what we haven't yet done actually is seen these things in nature, or maybe we can do that in the coming years, that would be cool.

• 37:39Brian Keating?

  As for the new book, I do hope you'll be narrating the audio version yourself. So check plus you did that. Without giving away any spoilers, what is your gut feel on dark matter? Is it a particle, primordial black hole? Or C, something like Mond, which he says is cringe worthy. I don't know.

• 37:58Speaker 00

  I'm a particle physicist, so maybe it's a bit like when you have a hammer, everything looks like a nail. But I mean, I imagine it's probably a particle because everything we know about is a particle. So it'd be surprising if it was something other than that.

• 38:11Brian Keating?

  We have, we have dark matter particles, they're called neutrinos.

• 38:14Speaker 00

  Yeah, we do. Exactly. Exactly. As to what kind of particles, whether they're wimps or axions or something else, I would remain agnostic about that until we have any evidence. I mean, the WIMP paradigm is coming under a lot of pressure from collider experiments, but also from direct detection where, you know, we're pushing really close now to this limit of observation of this neutrino fog where basically you can't tell dark matter apart from neutrinos or not very easily. So, I mean, I suspect it's a particle. I'm not, again, I'm not a cosmologist or a gravitation expert, so I'm probably not qualified. But I mean, from what I understand from people who are experts in these things, the broad view is that Mond is not the right approach. I mean, I found the kind of primordial black holes thing quite intriguing because it's a neat way of doing it without actually invoking any new physics.

• 39:00Speaker 00

  You just need, well, you need something in the early universe that can make these primordial black holes and you need them to survive long enough in the universe to still be dark matter and not have evaporated by Hawking radiation. And I think there is, I don't know, I think it seems to, when I hear different people, they say different things. Some people say, oh, there's still a narrow window where these things can have the mass of an asteroid or something. And they could be around, we wouldn't have seen through micro lensing or whatever. Other people say, nah, it's not really viable. So I mean, I'll leave that to the experts probably.

• 39:26Brian Keating?

  A topic that comes up quite frequently is a notion of what's called blinding, which is not what I think happened to your king Lear many centuries ago. What is blinding? Why is it so important? Not every experiment does this, but it seems to be quite powerful. So should every experiment be mandated to do a blind analysis? First of all, explain what is a blind analysis? And then how can it help to prevent experimentalists from going blind with their own in love with their own results?

• 39:52Speaker 00

  I'd move us start with a quote. So I think it's chapter three in the book. I begin with a Feynman quote, which is really close to my heart, which is, "The first rule is you must not fool yourself and you are the easiest person to fool." So blinding is basically a way of protecting ourselves from kidding ourselves or fooling ourselves. So the common thing we do in particle physics is you're looking for a new particle. A new particle, like the Higgs boson, the way it appeared in the experiment was as a bump in a graph. So you plot a graph as a function of energy. You get some little excess and that little excess is your hint that there's a new particle there. But what you're doing with your data, for example, you're cleaning it, you're purifying it, you're reducing noise. So let's imagine you're looking at that graph continuously as you're fiddling around with the different things you can do. And by doing certain things, you can move the background down.

• 40:36Speaker 00

  And you find, oh, a certain setting, I can make that bump a little bit bigger. And what you might actually be doing there is just massaging the data so that sort of some statistical fluctuation gets enhanced. And then you actually see a mirage that isn't really there. So that's why we blind ourselves. So the idea basically is applies in both cosmology and in particle physics and in other areas of science. You prepare all your methods, you decide how you're going to analyze your data. You write your fits, your data selection, all this kind of stuff. That's all frozen. That's all done. You agree everything with some kind of internal review committee usually in a big experiment. And then you freeze everything and you say, okay, we've tested this to the nth degree. We really believe what we're doing. And then there is this moment where you open the box and you're allowed to look at the result.

• 41:17Speaker 00

  And you, up until this point, you are blind. You can't look at the result. The result was often scrambled by some cipher. So in mu on g minus two, they literally had this number that was written out in an envelope stored in a Safe. And then I one at Fermilab, one sensor, I think the University of Washington, in case Fermilab caught fire and burned down and they lost the envelope. And this envelope was basically the frequency of the experiment's clock, because you need that to be able to figure out basically how quickly the muon wobbles and therefore how magnetic it is. So they literally this moment where they plug this cipher in and they see the result appear. And that is good scientifically because it stops you biasing yourself unintentionally. But it's also nice from a storytelling point of view because it gives you this moment of reveal where there's this kind of very dramatic

• 41:59Speaker 00

  opening of the box, but it's very, very common. It's very rare actually in the experiment I work on now for us not to blind ourselves. You have to really argue the case. Why you're not going to blind your analysis if you think that's what you need to do.

• 42:10Brian Keating?

  And then we look through all these experiments from DAMA, G minus two, even LHCB, bicep, you know, me close to my heart, but disappointing, obviously reason. Nevertheless, we learn from it to first approximation. If you were to form a prior or somebody claims some the prior should be that they're probably wrong, even if the experimental evidence seems to be many sigma. DAMA is what 20 sigma or something like that by now. How should we approach this as a scientist? Not, not, we can't be experts in every single field. You know, what level do we outsource our credulity in something to the sigma, to the confidence levels? Or what level do we really have to dig into? Maybe not the data, but into the methodology, the framework, that maybe the pedigree of the experimentalist, for example.

• 42:53Brian Keating?

  Uh, so that we don't, you know, fall victim to, you know, believing the bicep, the opera, the DAMA, the anomalies that turn out to be not. And, and for those of you who may be thinking I'm being too harsh on myself and Harry and our colleagues. I mean, it's much worse in other fields, legitimate fraud. I mean, the big pharma is not going to make much money if, if there turns out to be G minus two, turns out to be significantly deviant from the standard model. So how should, you know, a scientifically minded, most of my audiences, PhDs, masters, bachelors. How should we look at anomalies when, when they're announced? Because they're always announced to great fanfare. The Anita announcement was made at one time in the New York Post, which is like the Daily Mail or the Mirror in the UK. So how do we react to these things?

• 43:37Speaker 00

  In the book for when I interviewed Adam Rees and he talked about this professor that he had when he was a student. Young students would burst into his office like quite often with this. They'd have read about some new experimental result that was showing some anomaly. And the professor would just go, it's wrong, straight away, it's wrong. Go, you know, basically because he was an old wizened guy, he'd been through the works, he's seen how these things come and go. But there's, if you take that attitude, it's really no fun, I think, right? So there's two things in science, there's the actual acquisition of knowledge, but there's also, science is also, it's a spectator sport to an extent. It's fun to follow what's happening. You should be skeptical for sure, but if you become so skeptical, you just don't listen to anything and you don't engage in the process. Then I think that's a bit sad. I think you're missing out on something.

• 44:17Speaker 00

  But what I would say, I think in terms of anomalies, I mean, one of the, the problems that I think scientists have is often they're not in control of how.

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• 44:53Speaker 00

  All their results are communicated. So you mentioned Anita. I mean, so Anita saw these weird upward going particles coming out of the Antarctic ice. They were very cautious. They made no claims to what they were. They simply said, we've seen a couple of these events, we can't explain them. We've done what we can to figure out whether there's stuff in the ice that could be causing this. We, we don't have an explanation, but then that gets taken by some journalists and mangled and turned into this story. As much as they may try and dampen it down, that's kind of out of your control. So I think I would look at who's reporting it. If it's in the New York Post or the Daily Mail, they wouldn't necessarily be my first port of call for kind of reliable scientific reporting. So maybe go to Nature or somewhere like that first and see what they're saying.

• 45:36Speaker 00

  But sometimes people, I mean, it does happen that scientists overblow their own results. And I think, she, reading your book, the story of this big press conference around the Bicep two results. And they were pretty upfront about the claims they were making. And they weren't shy about it. And I think that is the sort of difference. That's where you can legitimately criticize scientists because everyone makes mistakes. I think it's totally, you know, if it's an honest mistake, we made a mistake. And I think what I'm quite proud of at LHCB is we were the ones that discovered the mistake as well. We found the mistake ourselves and then we put it out there. We didn't try and hide it. We were as upfront as we could be, we said, mayor culpa. And I think that's hopefully reassuring if you remember the public to say, okay, these scientists are harsh on themselves. They're going to fix their own mistakes if they can. Equally, we didn't make any great claims about this. We said, it's interesting, it's exciting.

• 46:20Speaker 00

  Maybe this is something, maybe it's not, but that's how science works. And I think with the history of science, often the way it's told, it's almost this linear story from ignorance to progress and knowledge. And that's not how it works. There are all these wrong turns, false dawns, but eventually you get there. So there's lots of bumps in the road and I think you don't want to miss out on the bumps. That's part of the fun of the of the journey.

• 46:39Brian Keating?

  Yeah, I would say we teach our students, at least in labs, we teach them. Science proceeds from Nobel Prize to Nobel Prize without loss of enthusiasm. I have one more question for my audience and then we'll wrap up with a big picture sweeping question for myself. So this comes from somebody, can't tell gender, Katerim Dow forty three. Anyway, does anything need to change in quantum mechanics to resolve the black hole information paradox? And what do you think is the cause of that problem, that this another anomaly? Not really discussed much in the book, but still important to you nonetheless.

• 47:11Speaker 00

  God, you're you're saving the easy ones for last, right? I mean, I mean, I am spectacularly unqualified to talk about the black hole information paradox. I am an experimental particle physicist. We do not make black holes. I do not know. I'm not gonna, I'm not gonna try and pretend I have an answer to that.

• 47:26Brian Keating?

  And that's what a good scientist should say. So how dare you ask a question? No, that is, that's exactly right. So I love it when I get a question, I'm finished talking about Bicep or Simon's Observatory, inflation, cosmic biorefringence and such. Well, global warming and what do you think about that? I'm like, look, I hope when you have someone, a climatologist talking about her work and you ask them about cosmology, they don't answer the question. I hope that they actually punt it to me or so one of my colleagues. Okay, last question. You open in the beginning of the book. With a wonderful quote from Isaac Asimov about the phrase, that's funny. So talk about what does that phrase, what does it mean to you that the way that a good scientist should react to anomalies

• 48:08Brian Keating?

  is not to be scared of them at all. Right? So how do you interpret Isaac Asimov's favorite statement?

• 48:14Speaker 00

  The quote is, the most exciting phrase to hear in science is not eureka, but hmm, that's funny. Science doesn't work by these moments of revelation. You jump out the bath and you've figured it all out. It's usually you're sitting in the lab or you're staring at some bit of data on a screen and you go, that's not quite right. What's going on there? I remember as a student noticing this with some of the more senior physicists in the experiment where you'd plot, you'd show a graph, some plot of some data, and you think it looked basically fine and boring. And they go, what's happening over there in the corner? What's that? And you go, I just thought it was nothing. It's probably nothing, right? And he's, I don't know. I think you should have a look at that. And then you look into it and you discover, oh, actually there's some effect that we completely missed that we need to take account of. And that's a kind of the instinct, I think, more experienced

• 48:56Speaker 00

  or more able scientists have. And we talked about this at the very beginning of the podcast, right? It's the people that have the kind of the instinct to follow those little clues that often make the biggest discoveries, whether that's Penzias and Wilson and their microwave buzz, or it's Rutherford and his blurry alpha particles. It's those little strange things that you really need to pay attention to. It's very rare that discovery reveals itself in a big flash in the way that maybe we imagined through the kind of popular tellings of the history of science.

• 49:22Brian Keating?

  Harry, thank you so much for sharing another brilliant book. What's, what's next? Another, another book in the works, or you have other?

• 49:31Speaker 00

  I've got an idea. I'm thinking about a book about nothing, but we'll see how that goes. I might even try and write a bit of fiction. We'll see.

• 49:37Brian Keating?

  It worked. It worked for Seinfeld.

• 49:39Speaker 00

  Yeah.

• 49:40Brian Keating?

  And Lawrence Krauss. Harry Clift, Dr. Harry Clift, thank you for joining us. I love talking to you. I'm always so excited when I see a new book. Everyone should go out and get the new paperback edition or the audiobook. You actually hear Harry's voice, which adds 10 IQ points. So he's up to 199 at this point, by my reckoning, Harry Clift. Good luck with all your endeavors, including a very important one coming up for you and your partner. Love talking to you and everyone, please check him out. Put links to all of his works, his books, his social media, his LinkedIn, where I follow him as well on here. And Harry, have a great day, great night. Thank you for staying up late, by the way.

• 50:14Speaker 00

  Thanks, Brian. It was a real pleasure talking to you. Great fun. Thank you.

• 50:16Brian Keating?

  As always, thank you so much, my friend.

• 50:18Speaker 00

  Cheers. Bye then.