Listener Questions about discoveries

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Speaker 1: Ay Daniel, where do you think the next big discovery in physics will come from? Oh? Man, if I knew that, I would be working on it right now, So it might come from anywhere, like particles or galaxies or anything in between. I think that's a pretty fair assessment. Yeah, that's like most of the universe. So is your strategy just look everywhere at everything all at once? Hey? I mean I think that will cover your basis. But you can decide what to do on a daily basis, right, You can't like study everything every day. I wish I could, But you know, everybody has one burning question about the universe inside them, So you just have to listen to your curious inner child to decide what's the most important question. Do you know, what if your inner child just wants to play video games, that's what my deals are mostly want to do, then maybe they'll discover the video on particle, yeah, or the roadblocks particle. Or what if your inner child just into snack, they'll discover the fundamental force that binds together the universe and the tasty on particle. I hear that one transmits flavor I am poor handmade cartoonists and the co author frequently asked questions about the universe. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and my PhD thesis was literally about heavy flavor. Oh yeah, was it a tasty thesis. It took a lot longer to swallow than I wanted. Did you make a cake out of it at the end and eat it? No, but it sounded a lot more like a good rap song than it actually was. You know, Oh, please give us a sample. Absolutely not, absolutely not. But heavy flavor flavor is my physics rap alter ego, just saying do you have a lot of bling also? Or you know stuff you've generated from a particle collider. I got ten billion dollars worth the stacks of hundreds you know that I spent on a particle collider. So that's pretty blinky. Oh I thought you were going to rhyme right there, Take a moment, do it. I'm not freestyle in man. I like big particles and I cannot lie. The other physicists won't deny. There you go. I was gonna say, my name is Daniel, and I researched particles. I published papers and lots of articles. I smashed him together like birds of a feather. Open your eyes and check out my Nobel prize. There you go, printed on a record N three d J Jazzy Jorge and Heavy Flavor. Maybe one of our fans we'll do that for us. We do have some fans with musical talents. I hope you guys all enjoyed that particle song. I've always wanted to be a loop in a rep song. I mean, you always wanted to get sampled, Yeah, looped around? Yeah, this is my chance. I just once the answer to a trivia question on a quiz show. I checked that off my bucket list. Was it which cartoonists didn't show up for the quiz show? Yeah? Unfortunately none of the contestants got it right. Nobody knew me, but I still I was I was a question. You know that's something. Yeah, I know that's a level of fame for sure. Anyways, Welcome to our podcast, Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we wrap at you about the nature of the universe, the way it works, the things we understand, the enduring mysteries of our incredible cosmic context. We want to understand everything that's out there. We want to distill the universe down into something simple and beautiful and mathematical, but fundamentally also explainable. We want to digest the universe. We want to intuitively understand it. We think it's possible by the universe to make sense to us and our tiny human brains, or at least we think it's fun to make banana jokes as we try. That's right, because it is an amazing and incredible universe that's also very tasty, and so we like to taste it for you and bring it down to your dinner table or our ears for you to sample and to go. That's delicious and the tastiest thing about the universe, if you ask me, is about how it's always satisfying our craving for discovery. We go out there, we ask questions about the universe. We do some investigations, and often we discover something surprising, something weird, something very different from anything we might have expected. Yeah, because we all hunger for answers out there in the universe. You know how it all works, what's going on, and how it all started, and where it's it all going to go. And we have this incredible technique that works pretty well if figuring it out. You know, we do experiments, we test them against theories. We sometimes see things that we didn't expect and have to go back and totally revise our ideas about the very nature of the universe. Yeah, and it all starts with something that all of our inner childs do on a daily basis, which is to ask questions. Everyone looks at onto the universe and then wonders and they have questions about what's going on. It's not just scientists and podcasters who ask questions about the nature of the universe. It's everybody. It's the physicist inside you, the philosopher who wants to know why the universe is this way and not some other way. So on this podcast, we don't just talk about the questions asked by academic scientists in their ivory towers. We love answering questions from you, our listeners. Wait, inside of me, I have an inner child and an inner physicist. Where are they the same person? And a philosopher too? Do they get into fights? You contain multitudes, man, But that's right. Everyone has questions inside of them, and everybody can ask questions about the universe and sometimes we take those questions and we answer them here on the podcast, we take questions from listeners and we break it down for you. That's right. If you have a question that you would like answered, something you saw talked about in a science article, or something that just doesn't quite fit right in your mind, please don't be shy. Right to us two questions at Daniel and Jorge dot com or tweet to us at Daniel and Jorge. We answer everybody's questions. We engage with everybody. We want to make sure you understand. And sometimes we'll get a question that we think I met other people have this question or just think it'd be fun to chat abou out on the podcast, and so then we ask you to send in some audio so that we can share your question with everybody. So today on the podcast, we'll be tackling listener questions Discovery Edition. Now, Daniel, did we have to pay the Discovery Channel to use the Discovery on our title? Here? You've gotta stop saying that, man, It costs us like a thousand dollars every time you say that d word. Do we say discovery the Discovery word every like five minutes on this podcast? We do exactly. I hope nobody's trademark curiosity, because then we owe them a big chunk of change. Man or banana? Do we all dull fruit like a bazillion dollars by now? You man, that's a you thing. Yeah. I thought we both owned this podcast. Are we both liable? My lawyer says, I'm just kidding. I hope that Discovery doesn't own that word. We certainly didn't pay them when we discovered the Higgs boson, Yeah, although it would have been a pretty minor cost compared to the cost of actually finding the Higgs boson. That's right. What's a hundred K and license fees when you've already sunk tin bill? Yeah. So we're tackling listener questions here today, and we got three pretty awesome questions from listeners. One of them is about the lifespan of particles, another one about consequential discoveries in physics, and a third one about Dyson's fears. Wait, that's not the vacuum cleaner, is it. Now? You owe those guys money too, man, Jeez, all of this ad money is going to our sponsors. That's right. We're gonna have to run this too, legal and listen to with here a heavily beeped version. Oh man, it's I feel like all of our money is going to go to lawyer fees. So let's get to it. Let's tackle this first question about the lifespan of particles. And this question comes from Elisa from Indiana. Hey, Daniel and Jorge, this is Elissa from Indiana, and I had a question for Daniel. At the large Hadron Collider, when you smash particles together, how do you actually observe what happens? Just the particles are so small and some last for such a short time. Also, is it only protons that you collide there? And why not electrons or neutrons? Thanks so much, looking forward to hearing the response. Awesome question, Thank you Elisa and Daniel. She said, this question is for you. Um, So I'll just take a break for like fifteen minutes. I'll come back, all right. We'll probably save money if you stop mentioning company names. Anyway, I'll save money and I can go work on other things. But it's a great question, you know. She's asking, first of all, how do we see the particles that we have created at the large a drunklider? We think we discovered the Higgs boson, but what does it look like? How can we tell that it's actually there? The particles are so small and don't live very long. It's a good question. Yeah, I wonder if she's asking with a tint of suspicion or skepticism, like is she is she asking like, are you really looking at things here that seems impossible? Well, it's a fair question, and you know, I guess she's maybe a reviewer number two on our paper. You know, she's asking if we really know what we're doing, And she's right, this is hard. This is one of the major challenges of discovering new particles is that they are very, very small, and they don't last for very long. You know, you might like to just take a picture of the Higgs boson and see what it looks like. But as far as we know, the Higgs boson is a fundamental particle, which means that it's tiny. It's really, really, really small. Technically, it's probably a dot, has zero volume. It might be made out of smaller things we just haven't seen yet. But the point is that it's smaller than any wavelength of light that we can shoot at it, which means technically we can't see it, right. You can't see things smaller than the wavelength of light you are using. That's why, for example, when we want to see really really small things, we use microscopes that shoot electrons at stuff, because electrons have a wavelength that's smaller than photons we can use in our microscopes. But these things are even smaller, and so we can't see them, and even if we could, they don't last for very long. The Higgs boson, for example, lasts for ten to the minus twenty three seconds before decays. It's like unfathomably short amount of time. So even if you could somehow build a chroscope to see this thing, you wouldn't have enough time to see it. So the short answer to her question is that we don't see these things. What we see is what they turn into. So the Higgs boson, for example, turns into a pair of other particles. Like every other massive particle in the universe, it doesn't like to stick around for very long. The universe likes to spread out its energy. You've got a lot of energy in a massive particle, it will decay into lower mass particles, just like the top cork decays or the neutron decays. All these particles decay into other particles, So the Higgs boson, for example, decays into a pair of photons or a pair of z bosons, and we can see those particles as they shoot out from the collision point. Wait, what what do you need me? I think what's interesting, um, is that maybe you can break this down into two things, right, Like one is how can you see particles that are that small? And two how can you see them if they last that long? Because maybe one thing that people do know is that you can actually sort of detect single particles in your colliders. Right, we can detect single particles, but only articles that are fairly stable, articles like electrons or even muans, which technically aren't stable, but they live long enough to fly through our detector. The image you should have in your mind is a tiny little collision point where the protons smash into each other. Then surrounding that are many, many layers of electronics that detect the passages of particles that come out of that collision point, the collision point itself, and we never even look at We don't see if we don't cameras focused on it at all, we just look at what comes out of the collision. So the collision point itself is embedded inside this huge detector which is like four stories high, and then it shapes sort of like a cylinder that surrounds the collision point. And each of those layers of detector can tell you when a single particle has passed through. So Higgs boson appears and turns into two photons. Each of those photons will streak through our detector and leave a characteristic signature we can so we can say, oh, here's a photon at this angle and this energy. There was another photon at that angle and that energy. We can put them together and say this must have been a Higgs boson. Yeah, I think you've made the analogy before that. It's sort of like a studying a car crash, Like you don't actually study the crash of two cars colliding. You actually just kind of arrive after the scene and you look at all the bits of debris that are spread around or they have spread around, and then you say, oh, this is what must have happened when the two cars collided. Yeah, it's just like that. You didn't get CCTV to capture the collision. You have to try to figure out who was to blame just by looking at the evidence afterwards, and so unfortunately we never get to like touch of Higgs or see a Higgs. But we're pretty sure that they exist because we have a bunch of collisions where a pair of photons came out, and if you reconstruct all the energy that those photons had, it adds up to a certain amount, and that amount is the mass of the Higgs boson. So the mass of the Higgs went into the energy of those photons. So we can reconstruct what the mass of the Higgs boson was. If you look at a distribution of where the photon pair energies add up to, you get this little bump at a hundred twenty g v where the Higgs boson is. So that's how we knew that the Higgs was there. We had a bunch of these photon pair events that all added up to the same value. Now, technically you can't look at an individual event and say these two photons came from a Higgs boson. We can just say it's more likely because there are other ways to make pairs of photons that look kind of like the Higgs boson. So in the end, it's also statistical. We can't say for any individual collision whether there was a Higgs boson. We can just say, in this year of collisions, we're pretty sure we made seventy five Higgs bosons, right, And I think at least's question was also that the Higgs boson doesn't last very long, Like it's not out in the universe by itself very long. It disappears or turns into other particles that do last a long time. And I think that's the idea, right, Like, it turns into things that do last for a while that you can detect in your colliders, and that amazingly you you can, like in your detectors, you can tell of a single photon or electron passed through a certain point, right, Like, that's how sensitive your sensors are. Yeah, And the sensors are specifically designed to tell apart the different particles, so we can tell whether an electron went or a photon, or a muon or a kon or proton, all these different kinds of particles have specialized detectors that are good telling those apart, so we can tell what it was and also really accurately measure its direction. And its momentum, so we can figure out what it came from originally. So that's the whole name of the game. You know, the accelerator complex itself cost billions of dollars, but these detectors also cost almost a billion dollars to build because they're really sensitive technology. Plus they have to operate in a really high radiation environment. They're getting blasted by particles all the time, so the only last few years they have to go in and take them apart and rebuild them, which is what we just finished doing. And we're just starting a new run of the Large Atter and Collider with our fancy refurbished detectors. Yeah, with a clear, clean set of lenses. Well, it's it's kind of interesting because this idea that you can detect single particles and maybe something that people hadn't thought about because you know, we all assume that particles are too small to detect, but actually, like your eyeball, it just can detect single photons, right, and your camera phones can detect single electrons or protons from the sky. Right. Yeah. We had an episode of recently about the eyeball as a single photon detector, which is pretty awesome and definitely. We have detector technology capable of seeing single photons, and so yeah, you can interact with these like quantum objects almost directly, which is pretty cool. Yeah. I think like if you're in a perfectly dark room, um, you could sometimes see a photon hitting your eyeball right, Yeah, And they do these crazy experiments where they take a single photon and they split it with a special crystal into two photons, one which gets shot at the experiment's eye and another one which goes into a receptor. So you can tell that a single photon has come and people will press the button when they see it, like they can see an individual flash of a photon. It's pretty cool. Okay. So the second part of Lesa's question was why do you smash protons at the Large Hadron Collider and why not electrons or neutrons. And I'm guessing it's not just because the name of the place is the Large Hadron Collider, because the other way it's called the Large Hadron Collider because we collide hadrons. But it's a good question because neutrons are also hadron, so why don't we collide deutrons? But first I like to mention that Protons are not the only things that we collide at a hat drun collider. We actually also smash other stuff. Sometimes we smash lead nuclei together. So you take a lead atom, you strip off all the electrons. You have this big blobb or protons and neutrons, and you take another one. You accelerate that in the collider and smash that together. Makes a huge messy splash, and people use it to study crazy nuclear physics scenarios like quark gluon plasmas that we talked about recently on the podcast Cool Well, why don't you collide electrons by protons and not electrons. So the tunnel that we use for the Large Hadron Collider is the same tunnel that we used for the previous collider at CERN, which was l EP LEFT, the Large Electron Positron Collider, So we have done e plus e minus collisions in the same tunnel. The advantage of using electrons is that they're very clean because their fundamental particles and they don't feel the strong force. So you get a collision and you know exactly how much energy went into it because you can control the energy of your beams, and the beams are fundamental particles. The disadvantages that electrons are very little mass and so they tend to radiate away their energy very quickly, so it's hard to get electrons up to really high energies. Protons are more massive, and so you can get them up to really high energies more easily without them radiating away all of that energy. So proton colliders are better at discovering really high mass stuff because you can get them up to higher energies than electrons. The disadvantage is that protons are not fundamental particles, the little bags of corks, So you're colliding bags of corks against other bags of quirks, and it's really messy because corks feel a strong force, so you get this gluon radiation everywhere. It's kind of a mess, but it has more power to discover stuff in the end. But can you just accelerate electrons to go faster to get the same amount of energy. You could accelerate electrons to go faster, but if you use the same tunnel, then as they turn, they would radiate away that energy really fast, so it's hard to get electrons up to that speed. Alternatively, you could use a bigger tunnel, so they don't have to curve as much because that's when they're losing the energy by radiating away as they bend. But then you need a bigger tunnel, which is more expensive. So if you have a fixed sized tunnel and a fixed strength magnet, then you can get protons up to higher energy than you can electrons. Well, also they have to be protons and electronics. They need to have a charge in order for you to not just accelerate them but make them go in a circle, right, because if it's a neutral particle, it won't go into circle, We'll just go straight. Yeah. We use electric fields to accelerate these particles, to push them, and then we use magnetic fields to bend them. And neutrons don't have a charge, so they don't get accelerated by electric fields and they don't get bent by magnetic fields. So a neutron collider might be interesting, but we don't have a way to build a neutron collider because they don't have that crucial feature, the electric charge that we can use to tug them along. Cool. Well, I think that's the answer for a Lisa, My question is why don't you smash other things just for fun toaster Oven's bananas, you know late at night. Has anyone been tempted to like, hey, what if we just stick a cat in there? Can you accelerate a cat? Cats actually do have a pretty good charge, but no feelines were heard in the production of this podcast. We've had a bit of a variety of our colliders over the years. We once build an electron proton collider. Do you smash on electron against a proton? Which is really helpful for seeing inside the proton and the electron like breaks up the proton gives you a nice view of the quarks inside. People are talking about building a muon collider where you're smashing Muon beams against each other. We also have beams of new trinos that we shoot against targets. We have all sorts of different kind of beams that we'd like to play with, but no nobody has a cat beam or a toaster beam yet yet. Well, right now we're making plans for the future of particle physics, and I'll make sure to add that to the list. Yeah, you know, everyone loves cats on the internet. So if you want a new headline the local viral, I think cats is your your main bit most expensive cat video ever. All right, well that's a question for at least I thank you're asking the question. So let's get into our other questions here about consequential developments in physics and also about Dyson sphere years. But first let's take a quick break. Right. We're answering listener questions here today, and we just answered a pretty interesting one about the large hadron collider and wide collides large hadrons. It's a large collider of small addrons actually, which is better than a small collider of large hadrons in terms of making discoveries. You're right, I know I hadn't thought about that. You know, you could part Are there small hadrons that you could collide to? Yeah? You know, hadrons are any particles that have quarks inside, and the proton has three of them. But you can also make particles out of pairs of quarks like kaons and pions some principle, there are smaller hadrons. Interesting, and also cats are made out of hadron so you could also have a feline hadron collider. Yeah, and if you have a pion pion collider, then you could you know, read do that famous cream pie collision experiment. But at the fundamental level. Oh my goodness, you might discover the laughyan or the slat stickne. We could convert one kind of pion into another kind of pion. You know, chocolate cream pieon into a banana cream pion. You could smash cats with cream pies. There's a viral video that will get us canceled, but it might be hilarious only you like animals. All right, let's get into some of our other questions here today. Our next question comes from Cavinda, who's asking this from Sri Lanka. Hello, Daniel and hor this is Carvin the My question to you is what are the five most consequential developments in physics that have taken place since the start of the show. Thank you very much for the knowledge enjoy you bring. Best regards from Sri Lanka. Awesome. It's great to hear from listeners all over the world. And the question is what are the five most consequence of developments in physics since the start of the show. I think the answer is zero, right, Daniel, I mean once we started the show, nothing more could be more consequential in physics than this show. That's right. Also, I stopped doing research since the start of the show, So how could anybody have done anything important since I'm not participating anymore? Yeah, there you go. Is that why you haven't produced any significant research in the last couple of years? That's not why did you retire like Michael Jordan's and you went into baseball or podcasting? Yeah, exactly. I retired at the top of my game. No, I haven't given up physics. I'm still working on it. But I think the question is really fun because the goal of the podcast is not just to like summarize everything we know about physics, but to keep people up to date and to like evolve with the time, and so physics itself is a dynamic, living thing. Right. Our understanding the universe is changing as time goes on, and so amazingly the podcast has gone on for long enough that our understanding the universe is different from where it was when we started. Yeah, we've been on the air for what three years now or more three and a half. Yeah, I think we're at almost four episodes and we do it out a hundred a year, so I think we're going on four years. Oh my goodness, where has the time gone? Into a black hole of podcasts? Alright, So in the last four years, what have been the most consequence of developments in physics. So we only asked for five. And this was really hard to think about what was the most important because there's so many fascinating discoveries. So for me, in no particular order, I would start with, you know, the Hubble tension. This is our attempt to understand the rate of expansion of the universe, and we measure it by looking at how fast things are moving away from us nearby, and how fast things moving away from us in the past. And we look at the very early universe, the cosmic microwave background, and we measure the expansion of the universe at all these different times, and we see different numbers and they don't really add up, which tells us that, like, maybe we don't understand something deep about the early universe. This is really fun because we were making sort of fuzzy measurements a few years ago and they didn't really agree. But people thought when they get more precise, I'm sure they'll all come into focus and agree with each other. But they didn't, and so that suggests like maybe there's something new going on. It's like a really big hint about something we might discover around the corner. Yeah, I think we covered this in a recent episode. This idea that we're sort of measuring the expansion of the universe at the beginning of the universe, and that we were measuring it through different ways and they sort of don't match. Right. One of him says that the universe was expanding or is expanding faster than the other. Yeah. If you measure at the early universe, the expansion you get is higher, and so the universe should be expanding faster. So that predicts it today we should see a faster expansion rate than we do. Is suggests the universe might be like a billion years younger than we thought it was. It could have gotten to this size faster than we thought, or it could be that there's a mistake in one of these measurements. It's kind of cool because no matter how we resolve it, we're going to learn something really interesting about something really important. We don't know what the answer is yet, but it's a big screaming clue that there's something big to learn. Yeah, or maybe the universe. That's just one of those people who look young, you know, just ages well, like the canaries of the universe. Could that explain it? Could that be a consequential discovery there? The universe has been using lotion all these years. That's the key, right, Yeah, the cosmic lotion theory. It's on a strict diet of snack yawns, which are pretty low calorie. All right, what's the next big discovery do you think that we've made in the least four years? Well, I think in terms of consequential developments, something that's been really interesting is that we haven't seen anything else at the Large Hagon collider. We found the Higgs boson in two thousand and twelve, and before we found it, we didn't know how heavy it was going to be. We didn't know there's gonna be a hundred times as heavy as the proton, and a lot of folks expected it to be much much heavier because the mass of the Higgs boson is we've talked about once on the podcast, is affected by all the other particles in the universe, and there's a bunch of ones that make it heavier and a bunch of ones that make it lighter, and those numbers are really really big, and they seem to sort of like weirdly balance out to get kind of a small value for the Higgs boson. Was suggests like, either the universe is fine tuned, it's like precisely put together in this way to give us a low mass Higgs boson, or maybe there's a bunch of other particles out there that are balancing it. So people really expected us to find a whole slew of particles with the Large Hadron Collider to explain why the Higgs boson is so low mass, but then we didn't, and that's had like a lot of reverberations in the field. It's definitely consequential. So sometimes a non discovery can be as significant as a discovery, right, But I guess maybe explained to us what that means. So if you haven't found any other particles after the Higgs boson, that means that the Higgs boson is smaller than you expected. Is that sort of like a big mystery? Then there's a lot of arguing about how big a mystery this is. You know, either the universe just is this way where some of the particles make the Higgs heavier and some of the particles make it lighter, and it just sort of weirdly adds up to a small value. It's like if you subtracted a ten digit number from another ten digit number, you'd expect to get something about ten digits. If you get something which is like very close to zero, you think that's a weird coincidence. And so in science, whenever we see a coincidence, we wonder is it just a coincidence or is there an explanation, and we hunger for an explanation. We don't like coincidences. We think probably there's a reason, and we want to know what it is. But you never know. There are coincidences in the universe. Right The Sun of the Moon are almost exactly the same size in the sky, which is why we have incredible ellipses. That's just a coincidence. There's no deep reason for it. So we still don't know. Is the Higgs mass a coincidence or is that a hint about something else that's happening that we could discover at an even bigger collider where we smash cats into banana cream pons. I think what you're saying is that the fact that you haven't discovered anything significant since the Higgs boson is significant in itself. Exactly, it really is significant. It's canceled a whole bunch of theories that people really expected to describe the universe. So it's really made us rethink our questions about the universe and how we try to answer them. It's been also a bit of a disappointment. You know, it's more fun to discover particles to not discover particles. But when you have specific predictions and they're not confirmed, you got to go back to the drawing board and think about what assumptions you made might have been wrong. Yeah, it also seems like a convenient way to put a positive spin on the fact that you haven't done anything, Like, how do we know you were even looking? Maybe you're just sitting around eating banana and clean pies. It's win win. If we discover particles, we say, give us more money to study these particles. We don't discover particles, we say, give us more money to discover some particles. It's a scam. It's an investment scam. All right. Well, that's pretty significant or insignificant, I guess, or significantly insignificant. What are some of the other great discoveries. Another one which really made ripples in my physics soul was the observation of gravitational waves. This is discovered by Lego and Virgo just about the time that we started the podcast, and for me, it's really changed the whole nature of astronomy and our understanding of what's going on out there in the universe. We've seen black holes smashing into each other, forming super big black hole and radiating away enormous amounts of their energy. In terms of these gravitational waves, which are these ripples in space and time itself, they propagate through the universe and then they squeeze these detectors that are like two miles long, and they shrink them by like a tiny factor smaller than the width of a human hair. It's incredible technological achievement that we can even see these little wiggles. Einstein himself thought it would be impossible to ever see them. It also means something really interesting about the universe. It means that gravitational waves are real. General relativity, the theory, which we're pretty sure is fundamentally wrong at some level, keeps predicting these crazy things and being correct about the nature of the universe. And it also tells us how often black holes collide, which is really often a lot more often than we thought. Yeah, it's pretty amazing to see ripples in the fabric of space time itself. It's it's like noticing that the world around you is squishing around, right, it's not like a fixed reality we live. Yeah, this is to me a really incredible avenue for exploration. It helps us really think about one of the deepest questions in physics, which is like, what is the fundamental nature of the universe? What is space anyway? And Newton thought space was just like eternal and unchangeable and just a backdrop to the universe. But Einstein showed us that it wasn't. That it's fungible, you know, that it's gonna be squeezed, that it can ripple, that it can expand it's really just like a dynamic thing. It's incredible, And now we've seen it do something that we had never seen it do before. So to me, that was a really consequential moment in physics, and it's continued to be We've seen now dozens of these black hole mergers and even neutron star murders, and so it's opened up a whole new eyeball, a whole new way to look at the universe right, right, although some people say it's it's more like hearing the universe, right, It's more like opening another ear to the universe. I know that the PR folks like to take those waves and change them into sound waves that you can play them. In the end, though, everything we're looking at his way is like you could take photons and turn them into sound waves if you wanted to. You're not really hearing gravitational waves. They're not like sonic ripples through the universe anymore than photons are. In my view, it's just a PR thing. Well, they're more analogous to sonic waves, right, because like the waves go up and down, right, they change in amplitude, and those changes in the amplitude tell you whether you know it's two black holes colliding or a black hole and ntron start Like there's something a little bit sound wavy about them, more than like just getting photons that tell you about the look of stars, I suppose. So in the end, we're always interpreting this data in a way that makes sense to us intuitively, and so we have to translate it into our senses. You know, when we see infrared radiation, we wave length shifted into the visible so we can look at those pictures. It's not what it actually looks like in real life because it's changing their frequency. But in the end we have to translate these things to our senses. Makes me wonder, like alien physicists observing gravitational waves, what do they think about them? Are they hearing them or tasting them? Whether they don't even have eyeballs, or what if they have four eyeballs, or what if gravitational waves are like a natural sense for them and so they don't need to translate it into anything. It's just gravitational waves. Man. Yeah, may they like to serve gravitation waves, who knows. But speaking of black holes, that's another pretty significant discovering. The last couple of years, we've actually gone into see black holes, right, We actually have We have pictures of the black hole from m A seven, and we also very recently have pictures of the black hole at the center of our own galaxy, Sagittarius, a star. It look sort of like crispy cream donuts floating in space, And you might think, like, what's the big deal If we really learned it's not just like a picture of a ring in space, what does that tell us about the universe. To me, it's really fascinating because it closes the window of what they really could be. You know, we measured the mass of these things, but we don't really know exactly how big they are until we can get a picture of them. We can see things like whooshing really close to the edge of the event horizon, and the closer we can see things passing by the black hole near the event horizon, the more we know about the density of that object we sort of close. Is the door on like other explanations for people who don't really believe in black holes. So seeing these images of black holes really is almost like a smoking gun that tells us that black holes are real. Right, I think we should send people who don't believe in black holes to a black hole so they can verify with themselves. No, I'm just kidding. Well, it's also an incredible technological feed. You know, these black holes that we took pictures of are incredibly far away, there in another galaxy, there in the middle of another galaxy, in between Brazilian stars that are shining bright. It's it's incredible that we can get a picture of something so far away, so small and in the middle of so many other stuff. Yes, technologically it's very impressive, absolutely, and also though does answer important science questions, it really does tell us something. You know, black holes are not something we can ever see directly, but you can only see their lack of radiation, and you can see their effect on the stuff very very close to them. And so the closer we can get our probes, the more we can be certain that these really are these weird divots in space and time. Yeah, or at least we think it was a black hole, right, there is still the possibility that it's something else, like a super dance star in the middle of there. Not technically about black hole. Yeah, we're still not know for sure, and to understand what's going on inside this reguion space and time will need some theory of quantum gravity, and there are other theories that are still consistent with these black hole pictures. So we are not a sure these black holes really are black holes, but taking these pictures helps eliminate some other theories that suggested maybe they were larger objects that extended past the event horizon. Yeah, it's pretty cool alright, So then what's the last in your opinion, big significant discovery in the last four years. Well, this is closer to my heart again. It's particle physics. We recently saw the mu on doing something kind of weird. Had this really precise experiment called G minus two. They take muance and they send them around a loop in the magnetic field and watch them. Will you did a really fun cartoon explaining the significance of this. Everybody should go check that out because it has Jorges awesome drawings explanations. But the short version is that the muans were wiggling a little bit differently from what we expected. When muans go around in these circles, they interact with all the quantum fields that are out there, and if there are more quantum fields than the ones we account for, then when the mu ones go around, they'll interact with those fields and they'll end up pointing in a different direction from the one we expect. And so they did this really careful calculation and this study for several years at the experiment, and they get a pretty different answer when they compare the experiment and the theory, which suggests maybe there are these extra fields out there. Right. Because there more fields there are, the more it will have this magnetic moment the particle, and so what they measure was that they'd had a higher magnetic moment than what our current lists of quantum fields sessors should be exactly. And that's sort of the field picture of it. Like thinking about particles, then you can imagine that as the muan is going around, there are these virtual particles that it can interact with. So maybe more fields or more particles out there in the universe, ones that might also explain the mystery of the Higgs Boson mass, though they might just be too heavy for us to create at the large aange On cliner. Pretty cool, pretty interesting, pretty tantalizing about our knowledge of the universe. It could mean that we are kind of wrong or incomplete about what we think is out there exactly. And so those are the most fun clues, the most consequential developments when we find out that we are wrong, when our expectation is different from what the universe tells us, Because that's the moment just before we make an incredible discovery, when we understand something new about the universe. Alright, Well, those are the five most consequential developments in physics in the last four years, according to Daniel Whitson. I should know that two of these are particle physics experiments which Daniel is in. One of them is his project which actually didn't find anything, but come out. It's still on the list. I'm just saying maybe you should go ask an astrophists just in case. Of course, these are very subjective. There are lots of exciting developments in other fields of physics as well. All right, let's get to our last question here on the podcast, and this one is a bout Dyson's fears in potentially using mythology to discover them. So let's get into that, but first let's take another quick break. All right, we're answering listener questions here on the podcast, and our last question comes from Chris Peg was wondering about how we can discover Dyson's fears. Hi, Daniel, and Johey, I was listening to a recent podcast when your guests mentioned dycense fees and how we hadn't found any yet. He's got me thinking how could we go about discovering a dicense fee. One thought I had was trying to use ancient mythology about disappearing stars, often devoured by some mythical being leaving the night sky dark? Could these stories be observed dicense fees? Is there any other way to tell Thanks for the thought of woking and insightful podcasts, all right, ask him question, Thank you, Chris. And he's asking how we can discover a Dyson sphere. And I'm guessing, Daniel, this is not the little ball that's in those Dyson vacuum cleaners. That's right there, dude, Oh that's right. I forgot wait I said discovering a din Sir. That's so that's double trademark fees that we over there. I should just say nothing. I think a lot of our listeners be like, yes, please horry stop talking. Nodes in sphere is a really fun idea that comes from Freeman Dyson, a physicist, and his idea was basically to make super solar panels. So you know, if you have a solar panel on your roof, it's absorbing the energy of the Sun and it's turning that into electricity or into hot water. The idea is, what if you build a bunch of solar panels, so you surrounded an entire star with solar panels, right, because think about the fraction of the Sun's energy that falls on your solar panels. It's almost zero. It's insignificant. So if you could wrap solar panels around an entire star, I think of the energy at your disposal. Yeah, i'd be massive, right, It'd be like the entire energy of the Sun that you could capture and use for like one thing or a lot of things. Yeah, you could build a laser beam to destroy planets, or you could use it for good. What could you use the giant laser beam the size of the Sun for to good purpose? Here? Oh, I don't know. You could beam the energy to planets around the Solar system that needed it. You could grow stuff on io and ghana, meat and all sorts of stuff. I mean, if you could harness that much energy, you could basically build anything you wanted in space out of asteroids. It can power an entire solar construction industry. We could build huge settlements in space. If we could zip around the Solar system on solar sales, it would be really incredible. Energy really is the limiting factor for our entire economy. Oh, that's interesting. It would be a way to sort of like harness the Sun and focus it on maybe the like the planets were really far away, like you could maybe heat up Neptune and make it habitable, or you know, heat up one of the movements of Jupiter and make it a nice tropical vacation spot. Yeah. I think this appeared in Isaac Asthmas story I read a long time ago. Solar panels that being that energy to various parts of the Solar System. Because remember, the Sun's energy goes like one overall distance squared, and so there's a reason that like Neptune and Urinus are called the ice giants because it's cold out there, and so we could capture all the Sun's energy and then beam it around the Solar system, then you can make a lot of these places really hospitable. Yeah, because if you think about it, the Sun is shooting off all this energy, but most of it is just going out into empty space, right It's it's sort of almost being lost because there's nothing there to receive it, or it's nothing there to really capture that sunlight. So there's a lot going out there in all directions that's not being used. Yeah. Well, maybe it's being used by alien astronomers who are studying our Sun and looking for our planets, but otherwise, yes, it's being wasted, and so the ideas that you can maybe build a structure around the sun, the whole structure of solar panels to partners that energy. And I think the question that Chris Peck has is like maybe we could detect it by seeing or looking at records or starts that have suddenly been covered up. Yeah, it's question is could we see if aliens are building a dicense fhere. And the idea is if somebody builds one of these things, then their star is gonna blink out of the night sky. So if aliens are putting this thing together, we should see a star disappear, and that would be a pretty cool signature because you know, we think we understand the life cycle of stars. They don't just blink out right, They blow up in supernovas, or they go red giant and expel their outer layers. We understand the life cycle of stars. So if we saw one that just like disappeared weirdly, that would be an interesting clue. If there are aliens who are building a dicense fhere around a star out there, it's kind of unrealized such a thing. They could do it in a in a single day, right, Like would it it maybe take thousands or hundreds of years. You know, like imagine building a structure the size of the Sun. It's it's like a million times bigger than the Earth. Yeah, it would be a big project, and to finish it in one day it would be exceptional. And so I don't know anything about alien engineering, but you can imagine that it would be making steady progress. So what you can do is look for stars that are steadily dimming, right, that they're getting dimmer and dimmer as time goes on. And we rely have been noticing some interesting things about a couple of stars in the sky. Beetle Juice for example, a very familiar star, remember the Orion constellation, the tenth brightest star in the sky and one of the largest stars visible to the naked eye. This thing is massive, like if you put it in our solar system, it would extend out past Mars into the asteroid belt. But the amazing thing about this star is that it's been dimming in the last few years. It's brightness has gone down by like a factor of three. So that got people wondering, like maybe the aliens have started building a dicensphere around beetle juice m and maybe they can do it in three days. Is that the idea build something the size of the sun in three days. Well, the problem with this theory is that it wasn't dimming steadily, and like went down and went back up, and then it went down, went the back up, and actually by February two thousand twenty two, it's back to its normal brightness again. And so it doesn't seem likely to be a dicensphere unless they were working on the dicensphere and they had some terrible accident and the whole thing blew up up right right, or they ran out of money they have to dismantle the whole thing in three days, you know. The leading theory these days is that there's some big dust cloud, maybe from a collision, like maybe beetle juice ejected some material in some huge coronal mass ejection which then floated out in cooled and partially blocked beetle juice for a little while. Or maybe like some exo moon came in and smashed into a planet and turned it into dust. You might wonder, like, how could we tell the difference if the star is getting dimmer? How can you tell what's dibbing it. But we do have one extra handle on it, which is that we can look at the different wavelengths of light we get from these stars. Because remember, stars don't just glow in the visible they also glow in the infrared and in the ultra violet, and those different kinds of light they passed through the universe differently, so ultra violet light and infrared light and visible light, some kinds of material are paked to those wavelengths, and other kinds of material are transparent. And so if we look at what frequencies it's glowing in, we can try to use what might be blocking it right, because I think the idea is that stars don't typically dim right, or at least dim in a time scale that we can notice. They don't typically change, and so if we see one dimming even a little bit, it's sort of as a sign that maybe something else is going on. Well, there are some stars that do damn their variable stars, but it happens since sort of a regular cycle, and we think we understand what's going on inside, and those typically happened on a fairly short time scale, So you can see it dim and come back and dim and come back. Sephids, for example, are variable brightness stars. But to see a star that's like just gradually dims and then eventually blinks out, yeah, that's not something we expect. And if you did build a dicense fear, if you surrounded your star with all this material, then we would expect that the star would go dim in all frequencies because this dicense here should be absorbing all of that light. But then the dicense fear itself would heat up a little bit, so you expect to see a little bit of infrared radiation from this thing. Like nothing in the universe is totally dark. So if they build a sphere to absorb all the energy, the heat of the sphere itself would glow in the infrared. So a signature of a dicensphere is a star that disappears and then you see something only in the infrared where the star was, you would see like the diceenosphere kind of burning hot, kind of the same way you could see the Earth. And the Earth itself doesn't glow, but if you looked at the Earth with an infrared telescope, you could see it, because the Earth does glow in the infrared, even though it doesn't glow in the visible right, you couldn't see the Earth from an optical telescope that uses visible light. You could see the Earth from other solar systems using infrared telescopes, which is why people are so excited about the James Web telescope, for example, could see exoplanets in the infrared. So if there's a dicensphere, we should be able to see it glowing in the infrared. So the Beetle juice was exciting, but then you know, the brightness came back up, and also it wasn't glowing only in the infrared the way you would expect from a dicensphere. All right, but there are other examples of stars dimming that might be hints that somebody is building a dicensphere out there. People are not excited about another star called Tabby Stars about light years from Earth, and it deemed about twenty two in its brightness starting in about two fifteen. People didn't understand initially what was happening to this star, But then again they studied the frequencies of light that were still coming from the star, and they noticed that the wavelength dependence of his dimming was consistent with dust. Dust was blocking certain frequencies of light but not other frequencies, So not consistent with an alien megastructure, right, which was again just glow in the infrared. So probably what's happening is again like some big collision, some new creation of dust is blocking this star. Probably not a dicensphere unfortunately. Well, I feel like these scenarios you're you're painting. Assume that we catch the dicensphere as it's being built like this, then we would see a star dimming, and then we would see a glowing infrared I wonder if Chris is wondering. His question is more about, like what if somebody already built one? Is there any way that we can see see it there? Like maybe it was built billions of years ago or hundreds of years ago, And could we tell it's there just from like you know, the fact that it would have the mass of the sun, but it would only be glowing dimly in the infrared. Yeah, that would be really fascinating. That's not the kind of object we expect to see. And so if you sensed its gravitational pull on nearby objects and then it was only glowing in the infrared. Then I don't know if anything else in the universe that could explain that. You know, we might expect that a white dwarf, the remnant of a red super giant that's left over is no longer fusing, would eventually cool into something we call a black dwarf. So you have a white dwarf, which is a big hot lump of metal glowing in space. Eventually it cools off into something that's so cold it's only glowing the infrared. But we think that would take trillions of years, and we don't think there are any black dwarfs in the universe. So something with the mass of a star that's not glowing except in the infrared, that would be a great candidate for a Dicen sphere. But those are hard to find, right. You have to like scan the sky in the infrared. Yeah, and you have to sort of know whether not has planets going around it. Right. The other fun part of Chris's question is whether we can use ancient records to see whether this happened a thousand years ago or five thousand years ago. Because people have been looking at the night sky for a long time, we have records like Chinese astronomers who saw supernova even though they didn't really know what they were looking at. So people have been carefully looking at the sky for a long time, which is a really fun idea. Yeah, And I think the idea is that maybe, you know, back then in ancient civilization, they didn't have telescopes or even photographs, but maybe you know, they were looking at a constellation and they saw that maybe one of the stars in the constellation disappeared, And if it disappeared, could it be that an alien build a disensphere at that time? That would be super awesome. I did a bit of digging to see if I could find anything an ancient record that hinted at that, and of course I'm not a scholar of ancient Chinese astronomy, but I couldn't find anything in the literature of that nature. What I did find is that there's a really fun project called Vasco, which is trying to look back at all of our photo graphic records of early astronomy. So you know, we've been taking pictures of the night sky for decades and decades and decades, and people are looking back through that to try to see, like Hey, is anything big changed since we started carefully documenting the night sky? You can't look at every single star as a person and notice whether it's disappeared or not. But maybe a careful study of these old photographic plates might reveal something. So this is a tough problem because these photographs aren't always in great condition. So it's sort of fun astronomical archaeology. Well, it's a lot of disciplines in one in one sentence photography as as an archaeology. Yeah, it's really fun, and it's fun to think about how in fifty years or a hundred years, people might be digging through our old data wondering if there's something that we missed. You know, there's all these examples of times in history when we make a discovery and then we think, hold on a second, somebody else should have been able to see that thirty years ago, and we look and we discover, oh, yeah, it's right there in their data. They just missed it. Nobel Prize winning to be found that nobody noticed. So scientists out there is entirely possible that the daity you're taking today, somebody else could be looking through it in fifty years or a hundred years and seeing your big mistake. Yeah, I'm sure we'll be talking about it in our four thousand episode. You know what has been the most significant discovery since we started this podcast fifty years ago. We discovered that we can do four thousand podcasts. Well, it's interesting. I wonder if you're like an astronomer in ancient times and you're like trying to convince everyone that a star that was there before is no longer there, Like, would people believe you right? Like, you're right right, You didn't take a photograph of it before. Why would they believe you that a start disappeared? They could be gas lighting you. They'd be like, I don't know what you're talking about. That's never been a star there. There's never been a star there. Yeah, you could gas light yourself now that they had gas light. That's right. But I guess if it was a pretty famous star when people were familiar with, you know, the North Star or something, and people would definitely notice if it hadn't disappeared. But yeah, there's nothing in sort of ancient literature that I'm aware of that suggests that that happened. I see, So, Chris Peck, I guess I'm keep looking. We're counting on you to spot that giant alien solar panels fear, and we're counting on all of you to keep asking questions and to keep sending them to us so we can talk about them on this podcast. We love your questions, but I love hearing you think about the universe and wonder about how it works, and I love helping you understand it. So please don't be shy and write to us with your questions. Two questions at Daniel and Jorge dot com. Yeah, and keep listening, because who knows when the next consequential discovery will happen, or Daniel's case, not not happen. It might be a Dicen sphere, or it might be some new kinds of particles. Stay tuned. That's the history of humanities, to stay tuned, because we were making discoveries all the time. Whoops, I just said the word again. I might run down the hall excitedly shouting, we didn't discover anything today again. Non eureka, non eureka. Right, you should celebrate every day, Daniel, that you don't get anything done. That's my philosophy. Doing a podcast is how I celebrate. It also keeps me from getting things done. So all right, Well, we hope you enjoyed that. Thanks for joining us, see you next time. Thanks for listening, and remember that Daniel and Jorge explained. The Universe is a production of I Heart Radio. For more podcast from my Heart Radio, visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.