Listener Questions #40

This is an iHeart podcast. Guaranteed human. Dell PCs with Intel inside are built for the moments you plan and the ones you don't. For the time you forgot your charger at the gate. Passengers, we are now on our initial ascent. Or when you're bouncing between projects like a ping-pong ball. We build PCs with long lasting battery life so you're not scrambling for a charger and built in intelligence so you can stay focused on whatever you're doing. Dell Technologies, built for you. Dell.co.uk forward slash Dell PCs. A puzzling relativity experiment posed by the thought, two spaceships accelerate. Does a string between them break or not? Parasitoid wasps use a virus to help manipulate. A collaboration which seals the caterpillar's fate. When the LHC smashes protons that have a huge energy boost, what kind of camera lets us trace the particles that are produced? Whatever questions are keeping you up at night, Daniel and Kelly's answers will make it right. Welcome to Daniel and Kelly's Extraordinary Universe, Listener Questions number 40. We're turning 40. It's a milestone. Yay! And you're going to round that up to 100, aren't you? What? Welcome to Listener Questions Episode Number 100. Congratulations to us! Hello! I'm Kelly Wiedersmith. I study parasites and space and today I get to talk about Parasitids and viruses, so I am very, very excited. Hi, I'm Daniel. I'm a particle physicist who likes to think about aliens and I don't like to think about crazy viruses or wasps. Then you picked the wrong co-host. Sorry, Daniel. I kind of do because it's fascinating and the science is amazing. And they're always incredible mysteries, but I often leave them wondering, am I having a nightmare about this tonight? But do you? No, I have nightmares about, like, turning into a pizza and being eaten or something like that. So they're much more nonsensical. Are you serious? Yes, that literally is what I dreamt about last night. I was like baked into a pizza, like fell into a pizza and then it went into the oven, which makes no sense because the oven is way too small. And then I somehow survived it and I was like, don't eat me. I'm in the pizza, but then people like me anyway. No. Oh, no. Tell me what that means, Kelly. I kept, I don't, I don't, I'm sorry to those out there who believe in interpreting dreams. I don't think it means much of anything. And I know everybody loves hearing about people's dreams, but I always dream that, like, I thought that I was auditing the course, but it turns out I wasn't. Nice. And now it's time for the final and I'm not really prepared. And that dream came true once. I thought I was auditing a course and I must have accidentally signed up for the real grade and I wrote the professor right before the final and I was like, ah, it was essentially just like a long email where I wrote, and he was like, dude, chill out. You're this is grad school. It doesn't matter what grade you get. And also you're doing fine and you're just Kellying out. Stop Kellying out. You're going to get a good grade. And but anyway, I was panicked. I was wondering if this story was going to end with, and then I woke up in a cold sweat and discovered it was a dream. No, I couldn't believe it was real when it happened. Like I looked up my, you know, my grades online and I screamed out loud. The student sitting next to me was like, what's wrong? Well, in your dreams, when stuff goes sideways, do you ever have the mental loop in the dream where you're like, oh, my gosh, this is terrible. I hope this is a dream because I can see no other way out of this terrible situation. That's definitely happened to me and I've woken up in great relief. Be like, it's a dream. We haven't all been eaten by caterpillars or something. Right. Let's get back on track and not psychoanalyze Daniel and Kelly's dreams because they either mean nothing or they're terribly embarrassingly revealing. And in neither scenario, did we want to dig any deeper? That's right. So let's instead dig in the questions that you have about the universe, things you want to understand. We get lots and lots of wonderful emails from lovely listeners who ask us things about the universe, about wasps, about spaceships, about the large cage on collider. And we love to answer your questions. Sometimes we even want to put them here on the podcast so that other people can hear the answers. That's right. And so today we've got three questions where, you know, maybe in some cases we looked it up and we didn't immediately know what the answer was. And so we were like, all right, we'll answer that on air when we figure out a longer answer. And some others were just like, you know what? Everybody wants to hear about parasitoids and viruses. So we should share this with the world. Let's risk nightmares across the globe. Yeah. Well, you know, you shouldn't listen to this show if you're not into creepy stuff, at least a little bit. Sorry. All right. Well, let's dive into our first question, which would only cause nightmares to people who specialize in relativity. This comes from a frequent correspondent from Portugal. Hi, Kelly. Hi, Daniel. This is Paolo from Portugal. I'm puzzled by the Vell spaceship paradox. Every time I read about it, I think I got it. But after a good night's sleep, I no longer have a clue about how it works. Not even sure if there's a consensus on whether the rope breaks or not. I believe the answer has to do with the concept of simultaneity and relativity. But I don't know how it plays out in this case. And another question, as I understand it, what happens here is that the distance between the two spaceships increases due to the fact that they are accelerating. Now, given that stuff on the surface of the earth is also accelerating, as you have often mentioned on the show, does this phenomenon also apply? Are the top of two skyscrapers slowly moving apart due to this effect? Thank you for taking the time to answer my question. And thank you also for the incredible work that you guys are doing. It's an enormous generosity from your part to be giving so much of your time to us, share your knowledge with us. And well, I'm immensely grateful to you guys for all the work that you guys are doing here. Thank you very much from the bottom of my heart. So here is where I admit that I had not heard of the Vell spaceship paradox before. It is not very widely known, especially in comparison to Vell's inequality and the entanglement experiment, which is what Bell is famous for. And Bell is only sort of tangentially involved in this one. But it's a really fun story when we get there. OK, so what is Bell's paradox? So Bell's paradox involves length contraction, the fact that when the things move fast, they look short. So relativity tells us two things. Moving clocks run slow and moving objects look short. So if you're watching a clock and it zooms by, you would have the speed of light. You see it taking slower than your clock. And the person holding the clock sees it taking normally. So this is an observer effect. You see moving clocks run slow. And if they're holding a meter stick, then you see that meter stick looking shorter than the meter stick that you have. OK, yep. I remember you explaining that in a prior episode. Right. And the crucial thing to understand about length contraction is that it's actually the same thing as time dilation. This length versus time thing is just two different ways to see the same issue. And you can see that if you dig into the details of what we mean by length and every paradox in special relativity is resolved the same way. You're using words slightly and precisely that implies something impossible or fuzz is over the issues. So you always have to be like sort of like an accountant or a lawyer. But like, what exactly do you mean here? And so we're going to be kind of physics, lawyery about what we mean by length. When we say moving objects look short, what do we mean? Well, we mean the length is smaller. OK, what does length mean? How do you measure length? Well, you can measure length by like putting an object against a meter stick and measuring where the back end is and where the front end is and subtracting. Right. Seems pretty basic. Yeah, that's what I do with fish all the time. But the crucial thing that you don't mention when you do that is that you have to measure the back and the front at the same time. Right. Because like if the thing is moving, if you measure the back now and you measure the front later, you're going to get way too long an answer. Right. If you don't measure the back and front at the same time. So, yeah, of course, obviously you measure the back and front at the same time. OK, that seems reasonable. But remember that time is relative in relativity. So what you think of as at the same time doesn't have to be at the same time for somebody else to events you think occur simultaneously, like Daniel measured the back and Daniel measured the front. I think they happen at the same time. Kelly on a spaceship moving past me will look at them and say, no, no, you messed up. You measured the back and then you measure the front, not at the same time. So remember, because time flows differently for different observers at different places in space, relativity also breaks the concept of simultaneity. So again, if a meter stick is flying by you, you might measure its length differently than the person who's moving with the meter stick because you disagree about what at the same time means. All right, so that's the root of the length contraction. OK, but we've got to get these fish measurements correct. So what do we do? What is the solution? Yeah, so the solution is actually it's not a problem. Oh, both measurements are correct. It's just that length is relative. OK, the length of an object depends on your velocity with respect to it. When you measure it being short because it's moving past you, you're not wrong. Right. It's just that you got a different measurement because length means something different, because at the same time for the back and the front means something different for me and for you. So in the same way that like you and I can disagree about the order of events and both be right, we can disagree about the length of the meter stick and both be right. All right. And so let's get to the paradox. All right. So what's the paradox? The paradox is you have two spaceships. They are separated in space by a kilometer. Now you tie a one kilometer string between them. OK, and you say let's fire your rockets at the same time, according to like the Earth frame and they accelerate. OK, so it's not just like constant velocity. This is acceleration, which is unusual for special relativity. Usually we work in inertial frames with no acceleration, but here spaceships are accelerating. And the question is, does the string break? And this is where Bell came in because Bell gave a seminar at CERN where he asked this question to a room full of physicists and most of them got the answer wrong. What? Most of them said the string does not break because it seems like it shouldn't think about what's happening here. You have two ships, they're accelerating at the same time. If they have the same acceleration, then they always have the same velocity. They have the same starting position. Then the distance between them should always be one kilometer. There's no reason why it should ever be different from one kilometer. If the string is one kilometer, then the string doesn't break because the distance between the ships matches the length of the string. Does that make sense? Are the ships the ships are going in the same direction? Yes, because I had imagined that the ships were going apart from each other. And I was like, this seems quite straightforward. Why would this drink not break? Crucial detail. Ships are pointed in the same direction, but one is a kilometer ahead of the other one. OK, and you tie them together with a string. They fire their engines at the same time. And so because they're accelerating at the same time, they always have the same relative velocity to Earth. So they maintain the same distance apart from each other. And so the string doesn't break according to the Earth frame. And that's what most of the physicists in the Seminar Hall at CERN said when Belle posed this question to them. Fools. Because that's what you might think would happen from the point of view of Earth. What happens from the point of view of somebody in the ship? Like if you look at ship number one, the one in the back. Well, remember that time is relative. And so what counts is at the same time according to Earth is not necessarily at the same time according to the ship, which now has velocity relative to Earth. And so from the ship point of view, the acceleration is not perfectly synchronized. Ship one sees ship two accelerating faster, essentially. And so the distance between them according to ship one grows because ship two is accelerating faster and then the string breaks. OK, so this what I'm going to ask the answer sounds obvious. But physics often gives answers that I think are not obvious, right? OK, so great. So yeah, great. All right. So ship two is like, oh, no, the string broke, because ship one started beforehand when you said from Earth, it appears like they shouldn't be breaking. But from Earth, you would be able to be like, oh, the string broke. So does that tell you that you were at the wrong frame of reference? Because the string broke. And so like you don't matter. Is that is that the point? The point is that the story from the point of view of Earth and the story from the point of view of the ship seem to be in conflict. And relativity, sometimes things can be in conflict, like we can disagree about the order of events, but some things we can't be in conflict about. Like the string breaks or it doesn't. Right. And everybody has to agree about that. So this seems like a paradox because the story from the point of view of the Earth says it won't break and the story from the point of view of the ship says it will break. And that's the paradox. So what is wrong? OK, I'm glad to hear that because I sometimes you all are like and multiple universes exist in a universe where it didn't break. And anyway, OK, so. No, that's why these paradoxes are fun, because you take this thing, special relativity where people can disagree and then you try to force a resolution like, well, who wins the race or which astronaut is actually younger? Right. And so the trick in these paradoxes is always finding like, where's the loophole? And so in this case, the answer is that the argument from the earth point of view is wrong. The argument that they're accelerating at the same rate. And so we'll always have the same relative velocity. And therefore the distance between them doesn't change. And so the string stays unbroken. That argument is wrong for one important reason, which is that the string is in motion relative to earth now. So the string shrinks due to length contraction. Right. We say things in motion look shorter. So these two ships maintain one kilometer distance apart, according to the earth frame, but the string gets shorter. So the string breaks. So that resolves the paradox because both points of view now say the string breaks for different reasons. OK. Right. And that's the beauty part in special relativity is people tell different stories about the same set of events. And those can be right. From the ship point of view, the back ship says, hey, the front ship cheated. And that's why the string broke. And from the earth point of view, we say, no, everybody played along, but the string shrank. And that's why it broke. All right. I'm confused, but totally follow you. Your explanation is clear. My mind is boggled. So this is fascinating wrinkle here, where the real rub is, is why the ships stay a kilometer apart when the string shrinks. Like you might also ask, why is the string shrinking, but the gap between the ships is not right? And the answer is that we set this up with this like magical ability for the ships to maintain one kilometer apart. Right. And so it's sort of like when you create an impossible object in a special relativity example, like I have a rod that's a light year long and I tap on one side of it, the other side moves instantly. Like, no, it doesn't. Right. You're assuming that that's possible when it's not here. We're postulating that the ships can somehow maintain a one kilometer distance, which is why the distance between them doesn't shrink. But the string has no such mechanism. And so it does shrink. OK. So Paul also asked about whether this would happen on earth because things on earth are spinning and that's acceleration. And so when a string between skyscrapers break, the answer is technically yes, but it would have to be a very sensitive string because we're not spinning very fast. The effect from relativity would be like one part in a trillion. So the string would have to be like extraordinarily fragile in order to be sensitive to this. Like, you know, the skyscrapers are going to wiggle in the wind much more than any effects from relativity. Got it. OK. Great explanation. Let's see what Paolo has to say. Is that how you pronounce? I think so. Yeah. OK. Yeah. Great. Sorry if it's not Paolo. Hi, guys. Thank you for another great explanation. I believe this paradox is a perfect illustration of something very fascinating about special relativity, namely the fact that two observers can tell a completely different story about the same event. And yet they are both right. One note to Kelly. When you're measuring your fish, be sure to be moving really slowly. And you nailed my name pronunciation. Surprise. We're here. Dad, what is that? It's a hungry horse. Dad, wrong hungry horse. This is a horse in a field. I meant the family pub with daily deals like buy one burger, get one for a pound on Fridays, candy, mania and free life sport. Oh, yeah, that does make more sense. Say yes to unbelievable value for the whole family. Say yes. Search online and book your table. Visit hungryhorse.co.uk for full season seas. Our answers actually make sense to you. Daniel and Kelly in the hot seat. And so if you were looking for something to have a nightmare about tonight, here's a question for you. Kelly is the person you go to. Hello, Kelly and Daniel. This is Petrie from Waterloo, Canada. I recently learned about wasps called brachanids that make their own viruses that they predatorily inject into their hosts. As I understand it, these wasps have virus DNA integrated into their own DNA, which is how they can manufacture them. Is this phenomenon real? I'd love to hear more about it. I love getting questions from Petrie. He's got some fantastic questions and his daughters contribute to our listener questions sometimes, which I also massively appreciate. Love it. So Daniel, do you remember what a parasitoid is? A parasitoid is something shaped like a parasite. No. That's what it sounds like. It should be to me like a parasitoid robot or something. But no, it's just a kind of parasite, right? Yeah, it's a kind of parasite, but particularly one that tends to kill its host as part of its life cycle. And on November 20th, 2025, for listener questions, episode number 22, we wanted to quite a bit of detail about jewel wasps, which are parasitoids of cockroaches. So let me remind you real quick what's happening there. So you have these beautiful iridescent wasps that want to lay their eggs on a cockroach. And so what they do is they tussle with the cockroach and I've watched videos of like jewel wasps and cockroaches fighting and it's pretty evenly matched. The cockroaches hold up pretty well. You don't care. I'm going off on a tangent here. And so anyway, the jewel wasps. I think that would be super awesome to watch if you were the size of a cockroach or jewel wasps like imagine going to an arena and seeing these things battle out like life size. Yeah, I know that would, but it would be petrifying. I once I once saw a wasp fighting a black widow and the black widow one. And I was like, wow, who are you rooting for in this scenario? Cockroach versus wasp. It wasn't the black widow because if I get stung by the wasp, I'm like, oh, ow. But if I get bit by the black widow that has like blood pressure implications. I don't want to go there. Well, what about wasps versus cockroaches? Are you pro cockroach? I'm pro wasp. These are really pretty wasps. Cockroaches kind of make me go, you know. All right. So cockroaches do so much useful. You know, they are scavengers. They clean up. They're not hurting anybody. They're just like eating our garbage, you know, but yeah, nobody wants to see them. You're getting paid by the cockroach lobby or something. I don't I'm not buying cockroach is funding me. Exactly. Yeah. All right. So the jewel wasp, if it's lucky enough, gets a sting into like the chest area of the cockroach and in the sting, it injects a venom. And that venom paralyzes the cockroaches front legs for like five minutes so it can't move. And then it stings it again in the head. And we go into a lot of detail in that prior episode about where it's going in the head, what it's doing. But essentially the cockroach is then like sound. Does it make when you inject venom into the head? It's like a. Or what? It's probably pretty quiet. I don't know that we've been able to record it. That's a good question. No, I want to hear your best guess. I don't know. I tried to make the noise you made. It's I don't know what you were thinking. I don't know either. It's just it was just so visceral. I had this image in my mind when you were describing it. I was just wondering what it sounded like. All right. So this is terrible already. I'm feeling really bad for the cockroach. What happens next? So the cockroach starts like excessively grooming itself and stays in one spot for a long time. The jewel wasp goes off and figures out where it wants to hide the cockroach. So the cockroach doesn't get eaten by anything. And so then it when it finds that spot, it grabs the cockroaches antenna and walks it sort of like a dog over to this little area. And then it lays an egg on the cockroach. And then it closes up the little hole. And when the egg hatches, the baby will consume the cockroach, which has pretty much not been moving and is just kind of hanging out in there. And it is a parasitoid because the babies are going to consume and kill the cockroach. And so it rides this thing like ratatouille, right? It's like standing on it, like driving it. No, no, it's not riding it. That would be really awesome. No, it's like holding on to the antenna and pulling the cockroach to where it wants it to go. I see. Yeah. So the antenna and screaming. Wow. It looks like it's going willingly. Like that that venom does some amazing things when it's injected into the brain of the cockroach. And what's the virus aspect of this? The venom contains a virus. It's like not enough for the venom to be like debilitating and humiliating and painful. It's also got to have like a DNA payload. Great question. So we don't understand wasp venom very well. So wasps have venom glands and when they inject venom into their host, it can contain a lot of stuff. And one of the things that it contain is virus particles or like viruses. And so we're starting to understand what these viruses do. In a lot of cases, we know that they're there, but we have no idea what they do. One of the things that they do and now we're moving away from the dual wasp example, that was just my definition of a parasitoid, my way of introducing the idea of venom. But now we're talking about viruses. Because they're in the venom. In some cases, they are in the venom. It's not the case that every parasitoid wasp has a virus in its venom. But in some cases, it looks like parasitoid wasps are also injecting venom and that that venom often helps the parasitoid wasp. So let's go for an example where the venom seems to be helping the parasitoid wasp. There is another kind of parasitoid wasp that lays its eggs inside of ladybugs or lady beetles, depending on what you want to call them. Oh, man. Now we're torturing ladybugs. Yeah, we've got a lot of not native ladybugs in this area. So they've got a sort of low sympathy, like they aggregate in my home at certain times of year. And I'm like over them. Sorry. What kind of person do you have to be to be angry at ladybugs? Like seriously? What are you saying? You try having them in your house and finding them on your toothbrush and being like, no, this is mine. Go away. I don't know. I don't have any trouble getting mad at ants or whatever, but like, leany mugs. You know, they're little predators, right? OK, anyway, let's go on and do horrible things to ladybugs. Man, biology is ruthless. Yeah, well, it is. So all right. So the wasp lays an egg inside of the ladybug and that egg contains a virus that was like replicating in the overduct of the wasp. So the baby wasp hatches and starts going through development and the virus starts replicating. And the immune system of the ladybug starts to be suppressed and the virus starts moving into its nervous system, like the ganglion in its head and stuff. And around this point, the wasp baby is ready to emerge from the ladybug and then it forms like a cocoon underneath the ladybug's legs. This is like alien, right? Where you lay an object and like crawls out from inside you and dances on the countertop and all that kind of stuff. Except in this case, the ladybug isn't totally dead yet. And so I know so she's got she's got this virus in her brain. And now she's got this like cocoon underneath where the baby wasp is still finishing some of its development. And whenever something comes by, she starts like having tremors and moving around like crazy, which is helpful for the baby that's developing underneath her. We call this bodyguard behavior because there are predators that want to eat. You know, what's inside of that cocoon in some systems. There are hyperperisatoids, so like a parasitoid that wants to lay its egg inside of the baby of the first parasitoid. How dare you? I know. Well, I mean, nature's meat all the way down, I think. And so so that you've got this virus that's like in the nervous system, making the ladybug do these like tremors. But the ladybug's immune system at some point starts to be able to fight back against the virus. And as it fights back against the virus, the ladybug first starts doing a lot of these tremors because part of the immune response harms the brain, it looks like. But then eventually the ladybug is able to clear the virus. And in some cases is actually able to walk away and live what I know after the and this usually happens after the baby wasp has like emerged and gone off as an adult to like make more of this horrible thing happen. I had given up on any sort of happy ending possibility here. I was like deep into nightmare territory. And now you're saying that ladybug can move on from this. Does it need therapy? I mean, is it OK? I mean, if ladybugs have therapists, I'm sure she's visiting one. But I don't know if that is an option. But yeah, it's crazy. And so these viruses have a couple of different ways of working with the wasp host. So in some cases, they're like replicating in the wasp. And when the mom injects the egg with venom, some of those virus particles get in there, too. And then there are also some. And this is what Petrie was specifically talking about when he sent the email in the video. There are some that actually have the virus DNA incorporated into its own genome. And so it will start making capsules for the virus to live in, and it will start making the virus on its own. And then it will put those two things together and inject that into the host. It like bruises its own internal virus kombucha and then forces the ladybug to drink it. It does. So in this system, the virus is not actually integrated into the genome. This is an example where it looks like there's some viruses. We're not exactly sure what's going on, but we don't think it's specifically in the genome of the wasp. So there's a couple of different ways this can play out. But but that's one of them. Yeah. So it's not part of the wasp. It's just like brewing this inside itself and then using it in the venom. Yes. Wow. Right. But when it's inside the genome, we call that a domesticated virus. It's been like taken up by the wasp. And now the wasp gets to use it as it wants. But those that DNA sequence keeps getting passed on across generations. So it's sort of like if a physicist's wife is making kombucha on her countertop, it's not part of her genome. But if she eventually domesticates it to be internal, so she could internally produce kombucha, that would be an example of a domesticated kombucha. And she might use it to manipulate you into, I don't know, doing the dishes more often, maybe twice your share. Or she wants to trick me into falling into a pizza. Maybe that's the whole plan. That she can eat you and get your energy. I'm going to make this all about myself. But that sounds fascinating. But I have a sort of obvious follow up question. I'm amazed that I don't see an answer to in the outline here, Kelly. Wait with baited breath to hear how I let you down. You're describing these incredible predators that inject venom into other creatures. And we recently had Matt Georgianni on the podcast to talk about snakes versus octopi. So the obvious question is like if you had snakes versus wasps, like venom versus venom, life size, what's going to happen? Or do we need to reach out to Matt to ask him that hypothetical question? Well, so I asked Matt a little bit about wasp venoms. And he suggested to me he wanted to stick with snake venoms, which I guess they're very different kinds of venoms. So my guess is if, you know, if a rattlesnake were to bite a wasp, just the sheer mechanical process of injecting the venom would just crush the tiny little wasp. It wouldn't have a chance if a wasp stung a snake. I don't know, it might hurt. Like when we get stung by wasps, we're not the intended target, usually, of the venom, but it still hurts. And so maybe a snake would also be like, dude, not cool. Cool. Go eat some ladybugs, man. That's right. I mean, I don't think it would get parallel. It would not, I imagine, get paralyzed like a lady beetle does, but it might be like, ow. All right. Well, thank you for answering my question. You're welcome. I was getting a little worried there. I thought maybe you were going to ask me for a scientific name just to mess with me or something. But no, I was like, two spaceships are separated by a snake. And then that snake approaches the speed of light and gets bitten by radioactive wasps. And then the multiverse breaks and there's three or four of them. And yeah, depending on which universe you are in determines who wins. But OK. All right. Before we get too far off track, let's send this response to Petrie and see if it answers his question. But I'm not done. So sometimes the wasps. I'm going to keep going. Please, I'm sorry. Yeah, Daniel, am I really only going to talk for 10 minutes about parasitoids and viruses? Give me a break, man. And so sometimes these viruses, you know, you'll find that a wasp has transmitted a virus to its host, but that doesn't necessarily mean that that's something that's good for the wasp. So we have found some other instances where it looks like the virus suppresses the host immune response. That would also be good for the wasp. But we've also found situations where it looks like the virus is making the wasp do something that's bad for itself, but good for the virus. Oh, like who really is in charge here? Right. Right. And so there's one system where the wasp usually tries to avoid laying eggs in a host that already has eggs in it because there would be competition between the offspring. And now you're like sharing the food source. But when the wasp is infected by this virus, it's much more likely to do what's called super parasitism, which is, yeah, I know. The Marvel Universe version. That's right. And that's where you get a wasp mom laying eggs in a host that already has eggs in it. And we think that that's good for the virus because the virus can now jump from the eggs that it was deposited in to the eggs of the wasp that had been laid there before. And so that's how the virus manages to expand throughout the wasp population. And super parasitism doesn't seem to hurt the wasps a bunch in this case, but it definitely seems to benefit the virus. And so you got to be careful when you study this stuff. It's often fun to be like, oh, man, it's a collaboration between the virus and the wasp. And they're ganging up on the host. But these things are complicated. And you need to think about like, you know, the end goal for every single one of the players and try to disentangle what's happening and. Yeah, game of thronesy or something. I wonder if it's sort of anthropocentric to ask like, who's really in charge here? Because in the end, the whole system is just sort of co-evolving, right? And whatever works is whatever ends up happening. Well, yeah. And you could imagine that like it could start off as antagonism between the virus and the wasp. But after a couple of generations, something might change and now they their interests are a little bit more aligned. And so, yeah, I think this kind of stuff could change over time, depending on how many hosts are available in the environment. This stuff gets complicated and humans like things in nice little categories and nature doesn't care. Right, exactly. And we like to attribute like intent to these things like the virus has this plan to trick the wasp into laying eggs where it's not good for it. But like the virus has no plan. It's just doing that and the viruses that succeed for whatever reason of the viruses we have. Yes, that's an excellent point. It's much easier and frankly more fun to describe these things in a sort of anthropomorphic way. But you're right, the virus isn't thinking, OK, now I have to do this, that, or you know, I now I have to make the wasp super parasitize the caterpillar. And you know, it's not planning that detail. There's no corporate board meeting where they're like, what if we super parasitize? How would that work? And they pitched it with PowerPoints or something. Exactly. Thank God, because man, then the viruses really would take over. Right. Yeah. And so I would say that this is a field that we are, you know, starting to understand, but there's a bunch of viruses that we see in venom. We don't know what they do. So we need to figure out what they're doing and, you know, how often they seem to be benefiting the wasp versus not open question. But super interesting. And now we can see what Petrie had to say, because now I've had my fill of the nightmare fuel. Let's see if that means Petrie will never sleep again at night. He's the one who asked the question. Buyer beware. That's right. Thank you very much, Kelly and Daniel, for the insightful response on your podcast. I very much enjoyed it. I never cease to be amazed and awed by the incredible ways life has evolved to manifest its diversity on our planet. I don't find it nightmarish at all. It's fascinating. But I also tend to sleep very well. Also, as someone who has spent a lot of time enjoying the fruits of home fermentation and happily shared these potables with others, I must say that I'm on the pro kombucha side of the debate. Even homemade bread ferments away happily on the counter while it rises before being baked. You know what you're getting with a football away game. The lucky shirt you wear every weekend. Tactical discussions. Just needs to shoot. Yeah, exactly. Cue for the turnstiles. Trying to get a chant going. Halftime pies. Hoping for a last minute winner. Happy with the point. Sometimes in life, you just know what you're getting, like a luxury bed and a great night's sleep at Premier Inn. You know what you're getting with Premier Inn. Gigaclear goes further to bring you fast, reliable whole home coverage. 100% full fiber, affirmative. Free Wi-Fi installation. Engineers ready to go. Amazon Eero Router next level. All from only 16 pounds a month. Cosmic quasars. Switch to Gigaclear. Faster broadband for rural Britain. 18 month contract prices may vary. Verify at gigaclear.com. All right. And now Eric has a great question about how we take photos of particles. Hi, Daniel and Kelly. I'm wondering about how particle accelerators actually detect things. I've seen lots of podcasts and shows in the past that talk about the acceleration and how that works and how you get the particles up to speed and smash them into each other. But then they just kind of wave their hands about detecting things. And they don't get into detail about what's actually being detected, what's actually being measured and how do you figure out what was in the collision. In high school, I remember looking at cloud chambers and doing the track analysis, looking at the radius and figuring out the mass and trying to work backwards. And I'm sure that's the precursor that's related to that. But I'd love to know what are the actual detectors, what's being detected, what are those machines? Are they just really complicated digital cameras or are there other techniques being used to detect and figure out what actually occurred in that collision? Thanks a lot. All right. Love this question. And you're right, Eric, we often talk about the fun bit where you accelerate the particles and smash them together. But it's also really important to understand how we make measurements of the things that come out of it, because in the end, this is quantum mechanical. All we have are measurements. And then we're trying to infer the story of what happened. So it's crucial to understand like, how do these detectors work? What are they really measuring? What do we know and what are we inferring? And you're right that you can think of these things essentially as big, complex digital cameras, because digital cameras and particle detectors are actually the same thing. Digital cameras are particle detectors. Like the way your camera works in your phone is it has a CMOS chip in it, which is like a layer of silicon. And when a photon hits it, it displaces a bunch of electrons. And then those get read out on the side. And that's a particle detector. Photon is a particle. And the fact that your CMOS chip can also see other kinds of particles like muons is the whole basis for my side project to build a cosmic ray detector out of people's old cell phones. What is CMOS? I can't. That's a word I've never seen before. What is that? How do you spell that? You've never heard of CMOS? It's this green fuzzy stuff that grows on rocks. Kelly. Oh, come on. I've heard of that. And if the thing you're about to tell me about is not spelled exactly like that, then I win. How do you spell? No, you win. It's CMOS, which stands for complimentary metal oxide semiconductor. It's just a way to sandwich various semiconductors so that you get this property. Then when a particle crosses through it, it trips a bunch of electrons that you can then read out as a current. It's a way to create a digital signal from the passage of a particle. OK, awesome. And it's also fuzzy and green. No, I'm joking. And so what we have at the large change on collider is like a generalization of that. It's like a big, fancy digital camera, but there's an important difference. It's not like we have a single camera that's just taking a picture of the collisions. We surround the whole collisions with sensors. So imagine like a sphere where you have like a bunch of cameras on the inside of it and you're taking a picture of what happens at the core of it. In our case, it's actually a cylinder because the beam comes in from the side. And then we have a cylindrical detector, which takes pictures of everything from every angle. And there are multiple layers of cameras. We have different kinds of cameras that can do different things, measure different properties of the particles. And so we get like not just one image, we get like another image and another image. It's sort of like if you have a red filter and then a green filter and then a blue filter, you can measure different colors at different intensities. And later you have a more complex reconstruction of what happened. So we have layers of detectors with different technologies and different abilities to help reconstruct what kind of particles came out. And are there detectors like around the entire length of the path that particles are getting shot? Or is it just like there is a region where all the detectors are? And that's where you're measuring what's going on. Does that make sense? Yeah, there's a region because there's a region where the collisions happen. So the beam circulate through the whole 33 kilometer long accelerator complex. But they only cross at certain places. OK. And those crossings are where the collisions happen. And that's where we surround with our detectors. And the detector itself is like a cube of electronics, like 50 meters by 50 meters by 50 meters very roughly. And what is the sound when two particles collide? Totally unreasonable, but very fair question. It happens in a vacuum and so it's totally silent. Wow, what a disappointing. But if I was asked to be a sound engineer for a movie in which very unrealistically a sound was made, it would sound like this. But you because these are tiny little particles. And even though they sound like they have a lot of energy, it's not actually that much energy from like our point of view. I think it would sound like. So let's go through the layers of cylinders for what happens around this tiny screen. And so we said we had layers and layers of detectors. The first ones are very similar to cameras. They are just thin sheets of detectors that try to tell us if a particle went through there. We call these trackers because we want the detector to leave a trace for each particle, like where did the particle go? So the particles fly through a very low mass material, like very thin sheets of silicon or dilute gas or super saturated water. That's what a cloud chamber is that leaves some kind of indication of where the particle went, but not to slow it down very much. We want to leave the particle mostly unchanged because these detectors are also immersed in a magnetic field. And that magnetic field bends the path of a particle if it's charged. And from the curvature of that particle, we can measure its momentum. So you try to figure out where was the particle going through this magnetic field so you can fit a circle to it and say, OK, this one had this much momentum. This one is curved less, so it has more momentum, that kind of thing. OK. All right. And so that's detector number one. That's the first layer in the tracker. And that goes very, very close to the actual collision, like the distance between the first layer detector and the collision point is like a roughly a centimeter. Now, you surround that tracker with something called a calorimeter, which is a useless name you don't need to know. And I should so I shouldn't have said it, but something that measures the energy, right? And the goal here is the opposite of the tracker. You want to slow it down as much as possible. You want it to smash into really high mass material so that it creates a shower of energy. One particle with high energy turns into two with half the energy turns into four with a quarter of the energy. Eventually you have a trillion particles with very low energy. And you can measure all those particles, like how much scintillation light do they produce is lots of different calorimeter technologies. But in the end, you're turning one particle with a lot of energy into a shower of particles that you can measure and using that to measure the energy of the particle. But I thought the particles had already broken apart because of the smashy, smashy that happened before. But now another smash is happening when it reaches the detector. Yeah. So the particles have broken apart and they created something new. Maybe it's a muon and it's flying out from the collision. So we're not trying to image the particles that went into the collision, the protons, we're trying to image what came out of the collisions because we don't know. And so different particles are going to leave different patterns in our detectors. But yes, we are creating secondary smashes in order to figure out what are those particles. Remember, you can't observe particles passively. You have to interact with them to know what is the momentum of this muon? What is the energy of this muon? In this case, we want the muon to smash into a block of copper and leave its energy there so we can measure what the energy of the muon was. OK. And does this get used up as you use it or because once you smash into the copper, does that mess up the copper atoms and then do they have to be replaced? Eventually, it doesn't mess up the copper atoms. No, it gets them a little warm and then they cool down. What does get messed up is the tracker. It's very close to the collision and it's much more delicate. And so after a couple of years of running in a very high radiation environment, it just gets trashed and we got to pull it out and build a new one, usually a better one, because by then the silicon technology has improved and we put in a new, faster, more robust, higher resolution one. But the calorimeters are pretty solid. You can use them for decades and then you can use them in another experiment. We'd like to build them out of high Z material, like depleted uranium or sometimes even lead or steel, but we like them to be low activity. And sometimes we even reuse material like some of the detectors I worked on from my PhD were refashioned from old Soviet battleships because that was like old steel. And so it was like radioactively quiet. Yeah, cool stuff. That's awesome. Yeah, exactly. So we have these basically two layers, the tracker and then the calorimeter. And then at the outside, we have another tracker for anything that escaped the calorimeter, anything that didn't leave a splash in the calorimeter. We try to get a record of that as well. Oh, and we have two kinds of calorimeters, one that's really good at making like electrons and photons make a splash and another kind that's really good at making particles that have the strong force make a splash. So then we have overall four rough categories of detectors, a tracker, two kinds of calorimeters and then another tracker. And then we play the match it game when a particle goes through. We see where did it leave a track? What did it interact with? What is its pattern? And then from that, we can tell what it was. So, for example, an electron will leave a track in the inner tracker because it has a charge and then it will make a splash in the first calorimeter and usually not make it to the second calorimeter. So that's what an electron looks like. A photon looks exactly the same. It makes a splash in that calorimeter, but it does not leave a trace in the tracker because it does not have a charge and you have to have a charge to leave a trace in that inner layer. So that's how you tell photons apart from electrons. OK, yep, got it. And protons look like electrons, except they don't leave a splash in the first calorimeter, they leave a splash in the second calorimeter. Muons hardly leave any splash. They make it all the way through because they're more massive than electrons and they leave a track in the outer layers. Neutrinos leave nothing at all. And so by playing this game of like, where did you leave a trace? How much energy did you deposit here or there? We can figure out what kind of particle each one was. So then we have this multi layer, every direction, digital camera to image every collision and then reconstruct what we think happened from it. Do you ever wonder to yourself, OK, we know what we want to look for for particles we're familiar with. Yeah. But like, there might be particles out there that we've never seen. And so we might not be detecting them at all because we don't have the right kind of detectors. Does that keep you up at night? Why are you dreaming about being a pizza when you could be worrying about this? Oh, absolutely. I wonder if there are particles out there that we can't detect or if there are particles out there that leave unusual traces in our detectors. So we're not looking for them. That's actually like a big part of my research project over the last few years has been using machine learning to try to reconstruct unusual particles, particles we don't anticipate. Because you're right, the strategy I just laid out for you was like, here's how you see the particles we do know. But these are computer programs, which means they're dumb. They follow your instructions. If they see something weird, but that's obviously a new particle, they were just rejected. They were like, that's not an electron moving on. That's not a muon moving on. So together with my students, we wrote a program which could identify unexpected particles, things that move smoothly and leave some kind of obvious pattern, but not according to any of these categories. Awesome. Yeah. That's definitely something I'm excited about. Yeah, I feel like this is what we're going to be talking about when we're doing your Nobel Prize acceptance speech episode or not. You're not going to do the acceptance speech on here. But anyway, when you're telling us about getting the Nobel Prize, you know what, if I win the Nobel Prize, I will livestream it for the pod for sure. Great. And I do not think that I'm going to win a Nobel Prize, but I do like to do research that has that possibility where there's like a small chance that we really are going to find something totally revolutionary. I don't like to do research where like, well, we basically know the answer. We just need to measure it a little bit better. I like swinging for home runs. Now, you're mostly going to miss. I've never hit, but you know, at least I swung. That's right. That's right. At least you swung. And I hope that when you make it big and you actually hit that ball, you remember us little people over here at DKU. That's going to be my favorite podcast episode when we do that one. All right. All right. Let's send this response back to Eric and see if we answered his question. Thanks for digging into how particle accelerators detect particles. You always mentioned that questions are welcome, but I think Kelly asked questions along the way that I had thought of and you addressed all of them. So thanks very much. I especially love to hear that people are thinking about that you worked on, how to detect things that you can't detect, which is I think is a really cool research. Have it in. Thanks a lot. Well, we have an exciting bonus question for everyone today. We do indeed am very glad to be able to sneak in an extra fourth question. And this extra question is from Lucas, who is nine years old and already thinking about the universe. Hi, my name is Chad from Atlanta, Georgia. And I have my nine year old son who's interested in science and physics. Hello, I'm Lucas, also from Atlanta, Georgia. And I want to know what you think about the universe in a black hole. More specifically, how can we use current physics to either prove or disprove the universe in a black hole theory? And how did we get into this? Thank you. Thank you very much, Lucas, for your question and a child for thinking about physics with your kids. Love to everybody out there who is raising the next generation of scientists. Talk to your kids about parasitoids, people. Only if you want to be holding them crying at 3 am. When you get to hug them. All right, we are far from the topic of Lucas's question here. Lucas is asking about this question about whether the universe is inside a black hole. And this is something we've talked about a few times on the pod. So I'll just recap it quickly for you. It's fun to think about the universe as being in a black hole because everybody wants to know what's in a black hole and it would be amazing if the answer was this. We are in a black hole. Oh, my gosh. Then we would know, right? Super fascinating and super fun. And there's reasons people think about this. There are superficial connections between our universe and a black hole. Like some theories say that a universe began with a singularity. And we think that there's a singularity inside a black hole. So like, hmm, that seems similar. But those two singularities are very different. The singularity that people hypothesize is that the beginning of the universe is a moment in time when everything was very, very dense everywhere. And the singularity at the heart of a black hole would be eternal. It would last forever, but would be at one point in space. So the Big Bang singularity is everywhere in space and a moment in time. The black hole singularities everywhere through time, but in a point in space. So already quite different. Yes. So it sounds like you're saying no. But there are other reasons people think it like there's the horizon coincidence. We know the black holes have an event horizon and our universe has a kind of horizon. There's a point beyond which you cannot see because life has not had enough time to get to us from there. So we can't see past there. Those seem like they kind of overlap. And even more than that, if you add up all the mass in the universe and ask what would be the radius of the event horizon of an object of that mass, you get roughly the length of the cosmic horizon. So you're like, hmm, well, that kind of seems like maybe we are in a black hole. But that calculation assumes that you're in an empty, non-expanding universe. So if you had an empty universe that was not expanding and you put our universe amount of stuff into our universe size bubble, then it predicts you would get a black hole. But we don't live in an empty universe. There's stuff beyond us and we are in an expanding universe. So that calculation is not valid. It's just kind of a cosmic coincidence. So there's no evidence that we're in a black hole. There are kind of a couple of superficial coincidences that hint in that direction, but they fall apart when you look at them more carefully. All right. Well, now Daniel has had his opportunity to be a wet blanket. All right. Thank you very much, everybody, for sending us your questions, for sharing your dreams, your nightmares, all of your curiosity with us. Yes. Please send your questions to us at questions at Daniel and Kelly.org. We answer every email. Daniel answers them in like 30 seconds. I take a few days and some of them even end up on the show. All right. Have a wonderful science filled day, everyone. Even the ladybugs and the cockroaches. Good luck. Thanks, everybody, for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us. Daniel and Kelly's extraordinary universe is edited by the amazing Matt Kesselman. He really is a wizard. You can also find us online on Blue Sky, Instagram and X, the end. K. Universe, come engage with us. You can email us at questions at Daniel and Kelly.org. We really do want to hear from you. And you can find our website, www.DanielandKelly.org, where you'll also find the invitation to join our discord where everybody comes and talks about the amazing universe. And we also have the most amazing moderators. This is an I Heart podcast. Thanks for joining us. 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