Daniel and Kelly’s Extraordinary Universe - Listener Questions #11

Episode Date: May 29, 2025

Daniel and Kelly answer questions about black holes, animal coloration, the big bang and time dilation.See omnystudio.com/listener for privacy information.

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Daniel's fave. What controls colors on our furry friends? It's biology, so it depends. Particle colliders make mini-booms, the Big Bang filled the whole room. Biology, physics, archaeology, and forestry, thank you for not asking about chemistry. What diseases do you get from your cats? We'll find answers to all of that. Whatever questions keep you up at night, Daniel and Kelly's answers will make it all right. Welcome to another listener questions episode on Daniel and Kelly's Extraordinary Universe. Hello, I'm Kelly Weiner-Smith. I study parasites and space, and I'm excited to learn more about black holes today.

Hi, I'm Daniel. I'm a particle physicist, and I love cats, though I don't have nearly as many pets as exist on the Weenersmith farm. Well, I mean, that's hard to beat. So you're a cat person rather than a dog person? Is that what I'm hearing? Well, I grew up with cats. Always loved cats. cats, but my daughter is allergic to cats. So now we have a dog and love my dog, of course. And so kind of a dog person now. But my daughter is getting shots so that she can tolerate cats. And we're hoping to get a cat soon. Oh, exciting. Now, are you going to adopt that cat? Where are you going to get the cat from? It was that or create the cat in collisions at the Large Hadron Collider. So probably going to adopt it. Yeah. Excellent. Well, we have a growing number of cats because we live on a farm in the

woods and they find us and then they move in and I can never kick them out we almost ended up with three beagles because they were also like dropped on the property and well saying no more animals I am like simultaneously dumping piles of food in front of them I can't help myself oh I see that was the other option the option is adopt cats or have them adopt you which is what you're doing on the farm yep yep although the goats I think I will be purchasing directly Well, there's some sort of gravitational cat hole effect there, I think, because the more cats you get, the more they attract more cats. And then cats hear about your farm. They're like, oh, wow, it's a cat haven. And pretty soon you're going to be a cat lady. Yeah, it's true. And we're also getting into chicken math. Have you heard about chicken math?

No, tell me about chicken math. It's when you decide you're going to get four chickens because it's not really that much work. So you actually get 10 chickens. And then before you know, with the order you put in actually had a four in the front. And now you've got 40 chickens. And anyway, I did duck. math recently. And so now we have five ducks and two geese coming. My husband's not excited about the geese. We decided we were going to name the geese Jacques Gusto and Francine Gusto. I think Jacques had two wives. One of them was Francine. Anyway, we're very excited. Well, at least you have control over the names of the pets, even if not the species or number of them. So it gets you a little

bit of illusion of control. That's right. All that matters is that they let me snuggle them. And in this crazy universe that can sometimes feel out of our control, one way we can sort of establish a little bit of a finger hold on sanity is to think about the universe and try to understand it, try to grapple with the mysteries of the cosmos. And the best way to do that is to start by asking questions. Questions we have and questions that you have. Chicken math might not make sense, but Daniel and Kelly's answers do. So if you would like to submit your questions about the universe, write us at Questions at Daniel and's Kelly. dot org and it might take us a little while before your answer airs because we are actually fairly well

organized and we're about two months ahead of schedule and we've got a bit of a list of questions but you will get an answer from us for sure we respond to everyone that's right right to us with your questions at questions at daniel and kelly dot org everyone gets an answer and some people get on the podcast and today we have questions from three listeners about black holes about furry pets and about tiny little bangs our first question comes from mark from Ireland about black holes. Here's Mark's question. Hi Daniel and Kelly. This is Mark from Ireland and I have a question about merging black holes. When two black holes spiraled towards each other to merge, they lose mass and in doing so generates gravitational waves. The newly formed

black hole will have a mass less than the sum of the two original black holes. My question is what actual mass is converted into gravitational waves, and how does this happen? In trying to get my head around this phenomenon, I see there are lots of other interesting questions that might arise. Maybe you can explain the merging process in detail. I really enjoy the podcast and look forward to new episodes. Thank you and keep up the good work. Whoa, great question. Okay, so I'm going to assume that we've never actually seen black holes collide, and we are guessing what happens. Or have we seen black holes collide?

Depends what you mean by seen and black holes. But yes, we actually have seen black holes collide. We've observed using gravitational waves, collisions of dozens and dozens of pairs of black holes now. It seems sort of fantastical and science fiction-y, but it's our reality. Okay. So then what did you mean when you said it depends what you mean by black holes and observed? Because it sounds like we have seen black holes collide. Yeah, I think most people in astronomy would say that we have seen black holes collide.

Okay. But, you know, we don't technically know that they are black holes. We've seen very dense, compact, dark objects, which are consistent with black holes, collide, that we've never really observed the event horizon directly. So there's an asterisk there on, do we really know black holes are black holes? And in terms of scene, we've observed the radiation generated by that collision. And that's what today's question is all about, how those black holes merge and the radiation they give off. So we've observed that gravitational radiation, and it looks exactly like you would expect from black holes colliding.

But I don't know if that counts as seeing it because it's not like visible light. Okay. All right. I got it. So let's start from the basics. What's a black hole? Right. So black hole famous prediction from classical general relativity, right?

This is Einstein's theory that space is curved. Gravity is not really a force. So what you think is gravity is actually just the effect of space time being curved. If you don't notice that space time is curved, it looks like something is bending the light or changing the path of the earth, but it's actually just the curvature of space time. Space time curves in response to mass. And if you get enough mass in a small area, it curves space time so much that things get trapped. Space time is curved so that light can't even escape. It's not like there's so much gravity, it even pulls on photons.

It's that space itself is bent so that inside a black hole, space only points towards the side. center. And so this creates the phenomenon we call the event horizon, beyond which anything that falls in is trapped. It will only move towards the center of the black hole. And so this is the defining feature of a black hole, the event horizon. This is the thing we haven't actually literally technically observed. We've seen lots of indirect evidence for black holes, but never actually observed the event horizon. And beyond the event horizon, we can't tell anything that happens. We can know the mass of the black hole. We can know if it has electric charge. We can know if it's spinning. But everything else is shrouded in mystery.

We've done 11 of these listener questions episodes so far. In thinking back, I feel like most of them have had at least a question about a black hole. What do you think it is about black holes that keep people up at night? I think it's an incredible prediction of physics, something so strange and beyond our intuition, but macroscopic. Right. Like quantum mechanics makes all sorts of weird predictions about electrons, what they're secretly doing while you're asleep, whatever. But we'll never see those because they're microscopic. topic. You can never observe them. Black holes are a prediction that are like, technically you could see, you could be near a black hole and observe it and see all this strange effects. So it feels sort of like magic, I think. And yeah, you're right. People are fascinated by black holes. It's a significant fraction of the questions we get are about black holes. So yeah, absolutely. It's fantastic. It's wonderful. It's incredible that we've actually seen and we've seen these collisions. I remember in the late 90s deciding where to go to graduate school and what to work on. And I had an opportunity to work on this project.

LIGO, the Gravitational Wave Observatory, and they were looking to see these black holes merging and the gravitational waves generated by them. And I remember thinking, they're never going to make that work. It's crazy. And so I decided not to work on that. And then, of course, they won the Nobel Prize. But, you know, hey, maybe if I had worked on it, it wouldn't have worked out. And they wouldn't have won a Nobel Prize. Maybe they won the Nobel Prize because I didn't work on it. Anyway. Hard to say. Do you ever regret not going into black holes? Or are you totally happy to with the path your life took. You know, there are always other options you could consider, but I'm pretty happy with

how everything worked out. And so, yeah, I don't worry too much about the counterfactuals. But it is amazing. The humanity has figured out a way to observe these collisions. Einstein predicted this decades and decades ago, but he thought it was going to be impossible to observe because gravitational radiation is very, very weak because gravity itself is not very powerful. And so you need an extraordinarily sensitive instrument to see this stretching and squeezing

of space time, this gravitation. radiation. Unless, of course, you're right next to the black holes colliding, in which case the signal is very powerful, and you're probably dead. I feel like that's another thing that gets people interested. The idea that observing this could kill you, but if you could survive what's on the other side, I just feel like it's amazing. But, okay, so we have observed collisions, and you said that we've observed a lot of them. And it was a little bit of a surprise when we saw the first one. You know, we didn't know how often does this happen in the universe. We're building our first eyeball for gravitational waves and how long it takes to see one, depends on how often they

happen. And there were lots of predictions. Some people predicted that it would take decades to see one, but they saw one almost immediately after turning the thing on. And it was like, oh my gosh, wow. So it turns out these collisions happen more often than people suspected. So does that mean we were totally off in our predictions for how many black holes there are or how much they're moving around? What were we wrong about in particular? So we're not sure. Black hole formation is still kind of mystery. Super massive black holes are things we don't really understand. So it's something we're still trying to understand. And we don't understand also the distribution of black hole masses. There seem to be some smaller ones, some bigger ones, but there aren't intermediate-sized

ones. So there's a lot we don't understand about black hole formation. How often it happens, how often they're close to each other, right? This kind of stuff. So a lot of really interesting astrophysics is being opened up by this study. No Goldilocks black holes. And Mark is interested in what happens when these two black holes form and where the mass goes? Because, you know, there's nothing free in the universe. If two black holes collide and produce gravitational waves, gravitational waves carry energy. They're the stretching and squeezing of space time. And that energy has to come from somewhere.

And it comes from the internal energy of the black hole system. These two things are orbiting each other. And for them to collapse down into one, they have to lose that angular momentum. So they radiated away in gravitational waves. And Mark's question is trying to understand where they're, the mass goes because the mass of the resulting black hole is not just the sum of the masses of the two black holes that go in. It's smaller than that because energy is lost to gravitational waves. And we have talked in other episodes about how energy is mass, but maybe not it's

complicated. Is that right? Yeah, mass is a measure of internal stored energy. Right. So like a proton's mass, it's not just the mass of the stuff that makes it up. It's the mass of the stuff that mix it up plus the energy they have relative to each other. In fact, most of the mass of the proton comes from that energy, the binding energy of the corks together. So if you have a black hole, black hole system, two black holes orbiting each other, the mass of the whole system is the mass of black hole one plus the mass of black hole two, plus their relative energy. And that's a lot. There's a lot of gravitational energy between those two black holes. Let's say black hole one is 40 masses of the sun, for example, and black hole two is 30 masses

of the sun, these are typical numbers, then the energy of the whole system would be 40 plus 30 plus whatever energy they have in their relative rotation. And that could be like 30 or 40 or 50, right, depends on the configuration. So the total energy of the system could be much more than 70. It could be 100, 120, this kind of thing. But a lot of that energy is lost when the two radiated away in order to combine. They have to radiate away some energy in order to combine. Otherwise, they would just orbit forever. And are they losing the energy of the black holes, or are they losing the energy that surrounds the black holes or a little bit of both?

Yeah. So this is a great question. And this is what Mark is asking. He wants to do some accounting. Is their mass actually lost? And I think he's interested in this because people think of black holes as something that can never lose mass, right? At least in classical general relativity.

And so he's wondering, like, is this a way for mass to escape somehow the black holes? And it's a little bit tricky. There's a couple things to keep in mind. And so the final black hole is smaller than the sum of the two original black holes, but always larger than either of them. So neither black hole shrinks. Both black holes grow. Nope, no, no, no.

You've lost me. Don't they become one black hole when they merge? Yes, they become one black hole, exactly. And so there's no shrinking of the event horizon. Like the final event horizon is bigger than either of the incoming event horizon. Okay. So no event horizon is shrinking. It's not like you're seeing behind.

the event horizon of either Black Hole. Both of them are growing, right? But the final is smaller than the sum of the two parts. It feels tricky, right? It feels like I'm cheating. Yes. So I guess what I'm not following is, okay, when they merge, I no longer think of them as two separate parts.

They're just one part. But it sounds like you are still trying to keep accounting on two parts, but now they've become one. So what am I missing? Yeah, think about it from the point of view of Black Hole 1. Okay, Black Hole 1. Okay, black hole one has an event horizon and it has a certain mass and you can just be in its reference frame and it has another black hole orbiting it, right? And then that black hole

radiates some energy and falls in and it gets gobbled up. Black hole one grows, right? So we followed all the rules of general relativity. The event horizon is not shrunk because it can never shrink because if it did, you would see things inside the event horizon. It has grown. Its mass has gone up, right? In classical general relativity, black hole masses can only only go up. So from the point of view of black hole one, the fact that black hole two is a black hole is kind of irrelevant. It's eaten some energy and it's grown. You can play the same game from the point of view of black hole two, right? The thing is symmetric. Black hole two grows. It gains mass. It's eating black hole one. The two merge. The final result is bigger than black hole two.

Everything is happy from a general relativity point of view. Okay. So at the end, you still have just one black hole. Yes. But that one black hole is bigger. than Black Hole 1 or Black Hole 2 were originally. Yes, exactly. Okay. And so it feels like mass has been lost, and we're playing some sort of shell game here. I think there's another thing to understand that might help people, which is the mass of the black hole doesn't just depend on what's beyond the event horizon. You can make a black hole more massive without crossing the event horizon.

So, for example, say I shoot Kelly into orbit around a black hole. Daniel. Hypothetically speaking. Or Zach, should we talk about Zach? Yeah, yes, of course. Zach is in orbit around a black hole. Okay. Now, that black hole's mass grows even before Zach goes over the event horizon, right?

You tend to think like, oh, it has to eat Zach before it grows to add to its mass. But the mass is a measure of the energy of the system, right? So the black hole's mass actually grows before Zach falls over the event horizon. So at what point does Zach become part of the system? Mm-hmm. well, when he has a relationship to it, like it's a gravitationally bound to it, then to an external observer who's like a little bit further away, like it's a black hole Zach's system.

The whole thing has more mass than the black hole or than Zach does. And so you don't have to like add stuff to the black hole over the event horizon in order for the black hole to gain in mass. This is actually crucial for the way that black holes actually grow in the universe. You might have heard, for example, if you do throw your husband into a black hole, you'll never actually see him cross the event horizon because time slows down, right? And a lot of people write it and say, all right, but then how do black holes actually grow if nothing can cross the event horizon because time slows down? But the answer is that the event horizon grows

before Zach reaches it. It grows out to meet him. He and the event horizon approach each other. And so if Zach was the last thing you ever threw into a black hole, it's true that he would never cross it, you'd never see him. But if after you throw Zach into a black hole, you feel bad and you like throw him a sandwich, then that sandwich approaches the black hole. And as it approaches the black hole, it pulls the event horizon over Zach, right? Because the event horizon comes out to meet the thing that's approaching it. Because again, the mass of the black hole depends on the stored energy, which includes the gravitational energy it has with things around it. So you shouldn't think of these things as just like boxes, right? Remember mass is not just like a measure

of how much stuff is inside the black hole. It's a more comprehensive measure of the energy of that whole system. You don't have to be over the event horizon in order to be part of that system. Okay, so one, the next time you say biology is complicated, I'm going to just start laughing right away. But okay, two, so if you threw Zach 10,000 sandwiches because you were like you're going to be there for a while,

would the event horizon pass Zach faster than if you just threw him one sandwich because you don't really care about what happens in the long run? Yeah, absolutely. Okay. And if you threw them in a sense, series, then chicken sandwich number one would pass first, chicken sandwich number two, then chicken sandwich number three. And the last chicken sandwich would not cross the event horizon.

So it's true you can't see something cross the event horizon if it's the last thing that you throw. But in our universe, there's never a last thing. There's always like more gas and more particles. And that's how black holes in the universe actually grow. All right. But back to Mark's question, what's going on here is that the mass of the whole system, right? Let's say we start with our example of a 40 and a 30 black hole and together they have a mass of like 120 right including all the gravitational energy and rotational energy as they inspire they radiate away a bunch of that energy so the mass of the system was 120 it's radiated away I don't know 60 so now the final black hole is 60 instead of 120 so 60 is bigger than 40 and bigger than 30 but smaller than 40 plus 30

but all that's happened is that some of that rotational gravitational energy has been radiated away. So even though the whole system started out with massive 120, now it's down to 60 because it's radiated away half of its energy. I'm just making up these numbers. They're roughly correct in the order of magnitude, but I haven't done like any calculations. But that's the right way to think about it as the energy of the whole system. All right. Well, I think I understand black holes better now, although I say that after every explanation and then I get things wrong the next time we talk about it. But let's see what Mark from Ireland, thanks of that explanation.

Hi, Daniel and Kelly. Thank you very much for that very informative answer to my question. I think black holes are really amazing and merging black holes are even more amazing. It's incredible that during the final fifth of a second of their inward spiral, that they are flying around one another at near relativistic speeds,

often up to a rate of 250 orbits a second and radiate the equivalent of multiple solar masses of energy in the form of gravitational waves. It really is crazy, crazy physics. Well, you've answered my questions very well and thank you both for taking the time to do so. I'm sure you'll hear from me again at some stage in the future and in the meantime, I'm going to keep listening in.

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From black holes to black spots, we are talking about patterns on our furry friends. Let's hear what Simon from Germany wanted to know about. Hi, Daniel N. Kelly, Simon here from Germany. Thanks for a great podcast. They're a fine background to my daily run in the woods. I have a question here for Kelly, one that has puzzled me for quite some time, and it's in relation to the coloration of our furry friends. So if we take a dog, for example, who is black and white,

and we zoom into the border between the two colors, presumably we have one skin cell or hair cell with black pigmentation, and the neighbouring cell has white pigmentation. The question is, how is this information passed down? presumably the information is contained in a precursor cell, one splitting into a black and one into a white. The question is, what is the mechanism for this? Thanks for a great podcast, guys. Keep up the good work, and I look forward to hearing some insight into this question.

See, biology also has really massively important questions. Are you being facetious? I can't tell. No, I'm trying to make a gravitational pun. Oh, good, excellent. Okay, sorry, it went right over my head. All right. So this was actually a fairly difficult question to read about and to try to understand. And it's biology. So it depends. Let me see if I can interpret the question to make sure I understand what he's asking.

Okay. I think he's basically trying to do some physics here, which is to like zoom in on the micro processes involved. He's like looking at his dog and seeing this white patches and black patches and wondering like what makes one bit white and one black. And he's trying to understand that by zooming in on the boundary and saying like, there's got to be a point where there's one cell that's white and one cell that's black. And that's where the difference is. And he wants to highlight like what's going on between those cells. to understand why one turns white and black, but also obviously to zoom out and understand, like,

how do you get these patterns? Yes, and that's how I interpreted the question as well. Okay. And the answer is that if you are looking at animal patterns in general, it depends on the colors, it depends on the pattern shape, it depends on the animal. But Simon in particular referenced dogs and referenced white and black.

And so I decided that I was going to hone in on that in particular. All right. Because I needed a foothold for this question. And so in dogs, there are hair follicles or fur follicles that produce either black or brown colors or yellow or white colors. So one follicle can produce either of those colors depending on the instructions that it's given. So it's not like you have different kinds of cells next to each other. It's all the same cell, but it just is following different sets of instructions. So they're just like printers and they can get anything.

instruction for a black hair or a white hair and they're happy to do it. That's right. Yes, exactly. Interesting. So who sends the instructions? So the instructions are encoded in a gene called a goody. And this gene is important for coloration in a lot of different species. And the gene produces a hormone. The hormone gets released from the cell. I'm a little confused because a gene is part of your DNA. And so when you're saying the gene produces a hormone, do you mean the gene when it transcribed into a protein is that hormone or the gene when transcribed into a protein is some little machine that makes a hormone or excuse my naive biology question no no that's a great question I skipped a bunch of steps so as I understand it the gene encodes for a hormone and so

when that gene is essentially red and turned into a protein that protein is a hormone that subsequently gets released from the cell the hair follicle cell or some other kind of cell that's controlling the hair follicle cells what I think is is happening here is that hair follicle cells are producing this message and then also sharing it with nearby cells. Oh, interesting. Okay. So the hormone gets released and it talks to the nearby cells. If you are a hair follicle next to a cell that has just released this hormone, then you produce white. Interesting. If you don't get that hormone message, you default to making black or brown. Wow, fascinating. Right. So cells can do either. And so,

the question is why are some cells making the signal that say turn on white and why are some cells not making that signal and telling nearby cells to default to brown or black? I love how we like follow the chain of logic here. Like this is happening because of that, because of that, because of that, because of that. And now we're like detectives following the clues all the way back to the source. So are you going to tell us who the killer is? Who is making these decisions about whether to produce this hormone? You know, it's biology. So the answer is never, you know, Colonel mustard. It's much more complicated. So you've got this a goody gene. And what determines whether or not genes are turned on or off is that there are these regions called promoters. And when

something binds to the promoter, that can turn the gene on. And so it seems that whether or not this hormone is made or not has to do with some complicated interactions happening with the promoter for the genes. And so some cells have these promoters turned on. So they're making this make white message. And some genes don't get this promoter turned on. So they are, are not giving a message in nearby cells make black or brown. Part of why I didn't get into the details is because it might help you understand exactly what's happening in this very particular instance. But to understand coloration in general, that's more a story about promoters getting turned on or off. So in general, then how do promoters

get turned on or off? I mean, this is part of your DNA. What determines whether or not that DNA is getting turned on or off? In general, we don't understand what's happening super well here. And we understand this process a lot better in rodents and birds. And in part, that's because we feel much more comfortable doing experiments on these animals in the lab. Oh, that's kind of sad. I know, I know. It is sad. But then you can also pick animals that have much simpler color patterns and fewer colors to boot.

And that makes it easier to sort of get a handle on these sorts of things, whereas dogs have loads of different color patterns. And so trying to get a handle on all of the different ways these patterns can be made is much more complicated. The manuscript that I read even had a sentence being like, the situation in dogs is still unresolved, but they're doing their best to figure it out. Well, this is super interesting how we can go from like totally clueless about it to understanding, oh, follicles can print either color, to understanding what controls what they print and then follow that up the chain.

And we're still crawling up the chain. It's incredible. It is incredible. And like I said, we've got a better handle on some species. And animal coloration in general is sort of fascinating. Like sometimes there are some animals that get it from their diet. For example, there are some fish that have red coloration that they get from the animals that they eat, and it just sort of like accumulates in their skin. That would be amazing if humans, for example, change color based on what they ate.

Oh, man, yeah, there'd be very specific kinds of diets, I imagine. And around Halloween, you'd eat like a lot more carrots to get in the mood. It would be great. Wow, amazing. You could get a tan just by having lunch. That would be incredible. And probably a lot safer than what we do. now to get tans. All right. So it turns out that Simon's question is cracked open a huge

canyon of unresolved questions in biology. And not only do we not understand dogs, but the whole question of how animals get color is still an active area of research and maybe having different answers in each species. Amazing. That's right. And so let's see if Simon feels like he learned anything from this answer. It sounds like Kelly read a lot of papers and learned a lot. Kelly read a lot of papers, learned a lot and also learned that there's a lot that she doesn't know about how this stuff works out. So it was a learning experience for sure. All right, let's hear from Simon. Kelly definitely did learn something. And I think we, as the audience, have definitely learned something

too. Thanks, Kelly, for the great insight into the invisible and incredibly complicated, it seems, biological mechanisms behind something as simple as the coloration of our furry friends. I think understanding how it works at this very last step perhaps gives us some insight into how it works at the very first step. So if I go back to the very first cell directly after conception, say, where it splits into two and then to four and then to eight and so on, eventually giving rise to something that resembles a head, a torso and four legs, to understand the finer details of how this information is passed down, how one cell knows to be a torso, while as direct neighbour knows to become a leg,

to understand how this transfer of information works from one cell division to the next would be fascinating to find out one day. But that's a question for another day. Many thanks, Kelly, for taking the time to look deeper into this mechanism and give us some insight into this very last step of cell division. Keep up the great work, guys. And all of a sudden, you hear this. Attention passengers. The pilot is having an emergency, and we need someone, anyone, to land this plane. Think you could do it?

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There's a lot of love that flows through this place, and it's sincere. Now it's a personal mission. I don't have to go to any more funerals, you know. I got blown up on a React mission. I ended up having amputation below the knee of my right leg and a traumatic brain injury because I landed on my head. Welcome to Season 2 of the Good Stuff. Listen to the Good Stuff podcast on the IHeart Radio app, Apple Podcast, or wherever you get your podcast.

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or wherever you get your podcasts. All right, we're back, and we're moving on from the mysteries of biology to the mysteries of the very early universe. Which one do we understand less? Does it really need to be a competition? We don't understand much about anything some days, it feels like. Leonardo wanted to understand the relationship between particle collisions and the Big Bang. Here's his question. Hi, Kelly and Daniel.

Love the show. I heard particle accelerators being described as tiny bangs, as in the Big Bang, but Tiny, in another podcast by Dr. Katie Mac. I also know we measure the energy of impacts in giga-electron volts, so can we also estimate the energy of the Big Bang in Electron Volts? And if so, why are we not classifying accelerators in Mili or Fentobangs? And is it because the number would be too unsatisfying? Greetings from Brazil.

All right, so Daniel, I remember you. telling me once that when you all turned on the particle collider for the first time, there was a little bit of a concern that maybe you would destroy the universe? Is that because you all thought you were going to kick off a tiny big bang? Well, you know, anytime you do something that's never been done before, you don't know what's going to happen. That's the excitement of research, right? You know, you're exploring the unknown. You're potentially unleashing something you didn't expect. And so, yeah, there's always a little frisson of, you know, enthusiasm and fear when that happens.

But when I first infect a fish with a parasite, I don't worry that it's the end of humanity. Like, the scale feels very different here. Maybe you should think bigger, Kelly, yeah. For those of you worried at home, we didn't actually worry about that too much because the collisions we do with the particle colliders are not unusual in nature. They're very high energy collisions from particles slamming into the Earth's atmosphere all the time, much higher energy than what we achieve with the Large Hadron Collider.

We didn't worry that we'd be collapsing the Higgs field or creating a black hole or anything like that. But it is a fascinating experiment because we are recreating conditions of the early universe. They're also conditions of our current universe, just not as widespread. And so it's often said that particle collisions recreate the Big Bang. And that's true in some sense, but there's also the potential there to sort of underscore misunderstandings about the Big Bang that we should probably clear up. Well, can we start with like, what is the defining characteristic of a bang of any size, small, medium or large? Yeah, that's a good question.

You know, in terms of the Big Bang, the Big Bang is more of a whiff than a bang, right? Because the universe is expanding, but it's really sort of cooling. It's becoming older and colder. So the Big Bang is a description of how the universe is decreasing in density as time goes on. It's cooling down and getting more dilute. So run the clock backwards, the universe gets hotter and denser. And we can run it backwards to a certain point, what we call the plank time, beyond which we know our theories don't work. And so everything is a question mark.

And that's what we call the Big Bang, is expansion from that moment. So it's a description of when the universe had very high energy density. It's not a tiny dot in empty space. The idea of a Big Bang, especially if you compare it to particle collisions, makes it sound like something happening at one location. But the Big Bang was everywhere. And so the similarity between particle collisions and the Big Bang is that both, have high energy density. Particle collisions, of course, though, in just one spot. The Big Bang was everywhere. Got it. Okay. And what kind of scale difference are we talking about in terms of

energy between big and tiny bangs? Yeah. So it's a pretty big difference. We compare these things in a weird unit called electron volts. And it's sort of a generic unit of energy. And you can also use it to measure mass because we don't care about things like the speed of light. And so an electron volt is our unit. And to calibrate, for example, a proton has a mass of one giga electron volt. So a billion electron volts is the mass of a proton. And collisions that we can achieve here on Earth are in the scale of 10 terra electron volts. So 10,000 times the mass of a proton. And that sounds pretty big, right? Like, ooh, wow, terra. Like, that's a big number. But protons are pretty small.

Protons are pretty small, exactly. And so the energy of the Big Bang in the same units is 10 to the 16 Terra electron volts. So 10 to the 15 times more energy than the collisions we have at the LHC. And 10 of the 15 is not a small number. You know, it's not 15 times. It's 10 to the 15. 10 with 15 zeros. If your bank account had one with 15 zeros in it, you'd be very, very rich, much, much, much richer than Elon Musk, probably like Elon Musk squared. So it's very, very high energy. If particle physicists had enough money, would you guys try to make a particle collider and you could do the Big Bang in? Because I'm not sure we can trust you guys. No, I think we would.

And the higher the energy collision, the more stuff you can make. We don't know what's out there in the sort of universe's menu of particles. And the incredible thing about these collisions is that you pour energy in and there's some sort of like quantum mechanical magic alchemy that happens. and the universe decides what from its menu to make, and it just sort of picks randomly from all the things that it can make, which means that if you pour enough energy into the collisions, you'll see everything the universe is capable of making

if you do it often enough. You don't even have to know what's out there. So it's like a way to explore the capacity of the universe without even knowing what it's capable of. You don't have to leave your house. You're just like, hey, make me everything you can make right here. And as you turn up that energy, you get to explore higher and higher on nature's menu.

And you could be just below the threshold and not make the thing because you don't have enough energy. And then you crank up the energy and boom, it starts to pop out. So, yeah, we'd love to crank up the energy of these things. We're still a factor of 10 to the 15 away from the Big Bang, which means there could be particles that were made in the early universe and they're super duper massive. And we haven't been able to make them yet.

They could be made in collisions of cosmic rays in the atmosphere, but they're very short-lived and we don't have detectors. there to see them. So check out Daniels go fund me for the next big particle collider. Leonardo's question also asked, can we measure particle collisions in terms of milly or femtobangs? And the answer is yes. So if you define one bang as 10 to the 16 T.E.V, then the large Hedron Collider has collisions at about 10 to the minus 15 bangs or one femtobang, which yeah doesn't sound very impressive and is not a great way to headline your science funding request. I don't know. I think femtron

But it's also a way to sort of trace back the history of the universe. Like as the energy of your collisions goes up and up and up, you recreate conditions that existed everywhere in the universe further and further back in time. And already 10 TV, one femtobang, is pretty high energy. It takes you all the way back to like microseconds after the Big Bang because the energy started to fall off really, really quickly, becomes more gradual as time goes on. So we are probing conditions in the very, very early universe, microseconds after the Big Bang. Well, let's see if Leonardo is impressed by Femtobangs.

Hello, I'm also in Tim Kelly. I'm also impressed by Fentobang. Also, thanks for clarifying the differences between particle collider and the early universe. I actually never considered that there could have been particles so massive that we will likely never be able to recreate. Thanks. All right. And today we have a special bonus question on gravitational and velocity-based time dilation from Asmitt. We decided we could squeeze in a fourth question for y'all. So here's Asmitt's question about time dilation. Hello, I'm Schmidt and my question is, what would happen to time dilation if both high-velocity and strong magnetic field interacted simultaneously? Would this cause time to slow down even more significantly or would there be no additional effect? Thank you. All right.

So Daniel, I have been listening while you talk. And I remember you told me there's two kinds of time dilation, gravity and velocity. But my brain is a sieve. So remind me what the difference between those is. Right. So there are two ways that clocks can appear slow. Now, clocks that you hold that you have with you always run the same speed. But if Kelly gives Zach a clock and then shoots them out of a cannon at a very high speed relative

to her, she will see Zach's clock running slow because velocity time dilation says moving clocks run slow. Now, Zach, with this telescope, looking back at Kelly's clock, will disagree. He'll say, no, no, no, Kelly's clock is running slow. So that kind of time dilation is symmetric, meaning both Weiner Smiths see the other one's clock running slow. And it leads to this sort of confusion, like whose clock is really slower. And the answer is, there is no really slower.

They can argue forever and both be right. So it's sort of a marital trap for the two of them. Yeah, that's not great. But the other kind of time dilation, gravitational time dilation, is asymmetric, which means everybody can agree on it. So, for example, if Kelly does drop Zach near a black hole, she'll see his clock running slower, but he will see her clock running faster. They agree in this scenario, but whose clock is running slower or faster.

Both of them see their own clocks running at normal speed. And so the cool thing here, and this is, Azmit's question is like, what happens when you have both? Do they constructively interfere, destructively interferes? Does universe explode? What happens? I hope the answer is Kelly is right. Whatever time Kelly says is the correct time. The answer is they both contribute. So let's say, for example, that Kelly launches Zach into orbit, right? Now, Zach is going really, really fast. And so his velocity means that his clock runs slower than clocks we have here on Earth from our point of view, okay? But he's also further from the gravitational well of the Earth.

So his clocks will run faster than ours because of the gravitational time dilation is less. So we have actually gravitational time dilation right here on the surface of the Earth because of the Earth. We're all experiencing it all the time. Clocks out in deep space run faster. So from Kelly's point of view, Zach's clock runs slower because of velocity and faster because of gravity. And the gravity actually wins out. So the velocity time dilation is like seven microseconds per day if he's up with GPS satellites and 45 microseconds per day the other direction due to gravity. So overall, gravity wins.

So when I shoot him into orbit, because gravity is winning and it makes things faster, he should still be on time or early. to the meetings. I'll have no excuse for being late. Is that right? I really feel like I don't want to get in the middle here. Physics is not going to solve your marital problems. All right, all right, but maybe sandwiches will. Sandwiches, yeah, well, exactly. Now, from Zach's point of view, both of the effects make Earth's clock slower. It's fascinating because from the Earth's point of view, we see the effects having different directions, but from Zach's point of view, he sees both effects having the same direction. He sees us moving quickly, which means our clocks run slow. And he sees us closer to a gravitational well of the earth, which means our clocks run slow. Oh, see, now I feel like you're

citing with Zach. This is no excuse. I feel like I need my lawyer present at this phone call. All right, everybody, thanks for playing. Just a reminder that you too can send us questions at questions at danielandkelly.org. We answer every question. Some of them end up on the show. and we can't wait to hear from you. And some of our questions come from conversations on the Discord. We encourage you to join our Discord where people ask and answer questions and make a bunch of nerdy jokes.

You can find the invitation on our website, danielandkelly.org. Daniel and Kelly's Extraordinary Universe is produced by iHeart Radio. We would love to hear from you. We really would. We want to know what questions you have about this extraordinary universe. We want to know your thoughts on recent shows, suggestions for future

shows. If you contact us, we will get back to you. We really mean it. We answer every message. Email us at Questions at Danielandkelly.org. Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms, you can find us at D and K Universe. Don't be shy. Write to us. entity has been fabricated. Your beloved brother goes missing without a trace. You discover the depths of your mother's illness. I'm Danny Shapiro. And these are just a few of the powerful stories I'll be mining on our upcoming 12th season of Family Secrets. We continue to be moved and inspired by our guests and their courageously told stories. Listen to Family Secrets Season 12 on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. It's Honey German, and I'm back with season two of my podcast. Grazias, come again. We got you when it comes to the latest in music and entertainment

with interviews with some of your favorite Latin artists and celebrities. You didn't have to audition? No, I didn't audition. I haven't audition in, like, over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending,

with a little bit of cheesement and a whole lot of laughs. And, of course, the great bevras you've come to expect. Listen to the new season of Grasias Come Again on the eye heart. Radio app, Apple Podcasts, or wherever you get your podcast. Hi, it's Gemma's Begg, host of the Psychology of Your 20s. This September at the Psychology of Your 20s, we're breaking down the very interesting ways psychology applies to real life, like why we crave external validation.

I find it so interesting that we are so quick to believe others' judgments of us and not our own judgment of ourselves. So according to this study, not being liked actually creates similar pain levels as real life physical pain. Learn more about the psychology of everyday life and, of course, your 20s this September. Listen to the psychology of your 20s on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. From tips for healthy living to the latest medical breakthroughs, WebMD's Health Discovered podcast keeps you up to date on today's most important health issues. Through in-depth conversations with experts from across the health care community, WebMD reveals how today's health news will impact your life tomorrow.

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