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Speaker 1: Y Daniel, I have a deep philosophical question for you. Awesome,

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Speaker 1: let me just get some Banan appeals ready over here.

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Speaker 1: It is a slippery question, so watch out all right.

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Speaker 1: So which came first? Physics or math? Oh, tough one.

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Speaker 1: I'm inclined to say math because people have been doing

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Speaker 1: that since there was like money. I think there are

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Speaker 1: cuneiform tablets they have found with receipts for like cows

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Speaker 1: that somebody bought in two thousand BC. So economics came first? Well,

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Speaker 1: you know, economics is doing math to describe the physical

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Speaker 1: world like cows. So in a way they're secretly physicists,

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Speaker 1: aren't they. I see, you're just trying to point it

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Speaker 1: all back to physics. So even if I buy a Hamburger,

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Speaker 1: I'm being a physicist. Well, you know, if you spend

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Speaker 1: money doing it, then I guess you're like a Mathematterian.

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Speaker 1: We're already saying that I eat math or I eat mathematicians.

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Speaker 1: That depends on your ethical framework. Man, what came first?

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Speaker 1: Ethics or physics? Philosophy came first? Would you get a

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Speaker 1: doctorate in those? I think podcasts definitely didn't come first, Hi,

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Speaker 1: am or Hammay cartoonists and the creator of PhD comics. Hi,

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Speaker 1: I'm Daniel. I'm a particle physicist and a professor UC Irvine,

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Speaker 1: and I definitely liked math before I liked physics. Really,

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Speaker 1: math is your first love or just your first experience

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Speaker 1: with the academics. Well, you know, you learn math in

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Speaker 1: elementary school, but they don't really teach you a lot

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Speaker 1: of physics in elementary school. I mean maybe you do

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Speaker 1: a little bit of like this is what it's inside

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Speaker 1: of rock, but you definitely don't talk a lot about

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Speaker 1: astrophysics in elementary school. I see, so Daniel Whiteson was

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Speaker 1: a mathematician before he was a physicist. Yeah, my dad

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Speaker 1: was really into math, and so I learned a lot

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Speaker 1: of math at home and I really enjoyed math and

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Speaker 1: elementary school. I was definitely a math nerd before I

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Speaker 1: was a physics nerd. That kind of makes me a

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Speaker 1: little sad. I feel like that's like learning that Michael

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Speaker 1: Jordans really wanted to be a baseball player and not

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Speaker 1: a basketball player. I think that's true, actually, isn't it.

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Speaker 1: It is true? Yeah, his first love was baseball. But

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Speaker 1: I'm pleased with any analogy that puts me in the

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Speaker 1: same phrase as Michael Jordan. I'd like to be the

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Speaker 1: Michael Jordan of anything. You are full of air hot

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Speaker 1: air sometimes. But you know, don't they say that all

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Speaker 1: babies are kind of physicists when they're born. You know,

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Speaker 1: they're trying to explore the physical world around them, and

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Speaker 1: they're trying to, you know, learn the laws of physics

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Speaker 1: in a way. Yeah, it sounds to me like you're

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Speaker 1: saying everybody who's curious about the world is a physicist,

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Speaker 1: not just curious about the physics of the world. You know,

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Speaker 1: like how do I stand up? Or what happens if

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Speaker 1: I dropped this ball? Or how do I get more food?

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Speaker 1: Although babies come from biology, so made biology came first?

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Speaker 1: Now I'm confused. It's all philosophy in the end. But anyways,

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Speaker 1: Welcome for a podcast. Daniel and Jorge explain the university

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Speaker 1: production of I Heart Radio, in which we treat the

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Speaker 1: entire universe as one grand physics question. We ask how

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Speaker 1: does it work? Why does it work this way and

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Speaker 1: not some other way? And how will it work in

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Speaker 1: the future? And most of all, we ask is it

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Speaker 1: possible for our tiny little mathematical biology? Economics philosophy, loving

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Speaker 1: brains to understand it. Yeah, it is an amazing universe,

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Speaker 1: and it makes me wonder if we are still just

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Speaker 1: kind of babies in it trying to figure out the

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Speaker 1: basics of how it works, or are we PhD holders

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Speaker 1: who pretty much are going to understand everything there is

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Speaker 1: to know about the universe right now. It is fun

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Speaker 1: to look back at that sort of history of physics

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Speaker 1: and how it developed, people stumbling forward, having silly ideas,

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Speaker 1: having to backtrack, having new ideas, and then bursts of progress.

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Speaker 1: It really is similar to the way kids develop. I mean,

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Speaker 1: physics are just like banging blocks together, you know what,

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Speaker 1: You know what, that's kind of what you're doing, just

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Speaker 1: banging particles together seeing what happens. Yeah, well, there definitely

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Speaker 1: are false leads and stumbling blocks, you know. I was

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Speaker 1: reading some history of physics yesterday, and even after are

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Speaker 1: like the Michaelson Morley experiment that light travels at the

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Speaker 1: same speed no matter who measures it. Most physicists still

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Speaker 1: believed in the ether for years and years afterwards. It

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Speaker 1: takes physics a long time sometimes to change direction and

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Speaker 1: figure out a new course, the same way it takes

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Speaker 1: kids time to break old habits. Yeah, tell me about it.

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Speaker 1: We tried telling a kid what to do or try

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Speaker 1: to instill the habit of cleaning up the room. Impossible, impossible.

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Speaker 1: And so I hope that we are still babies when

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Speaker 1: it comes to the physics of the universe, because that

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Speaker 1: suggests we're going to grow up into some new, deeper

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Speaker 1: understanding of the way the cosmos works. That in our

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Speaker 1: future are some revelations. Yeah, we're gonna get PhDs in

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Speaker 1: PhDs or something, But there is still plenty to understand

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Speaker 1: about the universe and all the mysteries of the cosmos,

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Speaker 1: how it works, how things swirl around each other, how

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Speaker 1: things form, how they burn, how they die, generate questions,

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Speaker 1: not just in the minds of academic physicists, but in

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Speaker 1: children and in everybody out there. Yeah. Maybe in a

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Speaker 1: way before math or before physics or biology or philosophy

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Speaker 1: came just asking questions like that's kind of how everything

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Speaker 1: starts by a human asking a question about how something works. Yeah,

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Speaker 1: proto humans asking questions like how fast do I have

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Speaker 1: to throw my spear to get that mammoth? Yeah, that

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Speaker 1: it sounds like more of an engineering problem, Daniel, We're

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Speaker 1: all proto engineers. Is that what you're saying before asking questions?

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Speaker 1: We're engineers. We ask questions and the answers lead to

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Speaker 1: engineering problems, like all right, I need a spear this long,

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Speaker 1: somebody build me one. Yeah, well, I'm regardless of who

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Speaker 1: came first. What's important is that we ask questions. That

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Speaker 1: seems to be a very common human trait that everyone doesn't,

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Speaker 1: no matter how old you are or where you come from,

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Speaker 1: because we all look at the universe and we wonder like,

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Speaker 1: what's going on, how does it all fit together? And

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Speaker 1: what's going to happen next? And if you're listening to

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Speaker 1: this podcast, probably you're the kind of person who desperately

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Speaker 1: wants to know the answer to these questions. Feels like

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Speaker 1: there is a truth out there about how the universe

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Speaker 1: works and how it began and what its future holds,

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Speaker 1: and we want to know it because we believe that

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Speaker 1: if we apply our minds, we can understand the universe. Yeah,

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Speaker 1: and it's not just physicists asking these questions. It's people

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Speaker 1: like you asking these questions. And sometimes listeners like you

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Speaker 1: send their questions to us, and we invite you to

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Speaker 1: send your questions as well. If there's something about the

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Speaker 1: universe you don't understand, or you'd like to hear us

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Speaker 1: talk about and make silly jokes about. Please write to

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Speaker 1: us two questions at Daniel and Jorge dot com. Yeah,

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Speaker 1: Daniel answers every physics questions he gets, even if they

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Speaker 1: are crazy out there, right, that's right, And not just

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Speaker 1: physics questions. AHI answer every message I get from our listener,

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Speaker 1: even funding requests. He takes that funding requests. I guess

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Speaker 1: you can always answer it. No, I'd always answer no.

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Speaker 1: Sometimes people ride in with life advice questions like I'm

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Speaker 1: forty years old and I'm a computer programmer, but I

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Speaker 1: always wanted to be a physicist, and is there a

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Speaker 1: way for me to get there? Cool life advice, career

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Speaker 1: advice from a physicist, Life advice from somebody who doesn't

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Speaker 1: really know how the real world works. Yeah. So sometimes

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Speaker 1: we get these questions, and sometimes they're so interesting Daniel

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Speaker 1: puts them up to answer on the podcast live in

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Speaker 1: front of a studio audience. Who's the studio audience exactly

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Speaker 1: by the laugh track, Now it's the studio in my head.

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Speaker 1: We have a live audience in my head in front

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Speaker 1: of the studio audience of nobody know. Sometimes I get

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Speaker 1: a question that I think we'll be fun to talk about,

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Speaker 1: or I suspect other people will want to hear the

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Speaker 1: answer to, and so then we get audio from that

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Speaker 1: listener so we can talk about it here on the podcast.

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Speaker 1: Yes to the On the program, we'll be tackling listener questions.

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Speaker 1: Remember that's the six episode in which we answer questions

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Speaker 1: from listeners. That's right, and last time we did this,

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Speaker 1: or hey, you had so much fun, you said we

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Speaker 1: should do this more often, And so here we are again,

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Speaker 1: just a couple of weeks later, doing it more often.

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Speaker 1: Oh man, I didn't know I had that kind of

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Speaker 1: influence in the universe. Should I wish for more things?

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Speaker 1: Oh man, Daniel, I wish I had a bazillion dollars.

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Speaker 1: You can submit a request to the Daniel Science Foundation,

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Speaker 1: but they usually say now do they ever say yes?

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Speaker 1: What's their track record? Zero percent? We responded to all requests.

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Speaker 1: I see response rate zero percent, affirmative response. We have

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Speaker 1: issued of our foundation of bank account, have issued knows

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Speaker 1: in your operations. That's right. But anyways, we're so we're

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Speaker 1: answering questions from listeners today and we have some awesome

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Speaker 1: questions here today, some from kids about the Solar system

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Speaker 1: and the planets in the Sun and the moons around us,

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Speaker 1: and also some interesting questions about asteroids that may or

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Speaker 1: may not kill us, and also about matter and energy

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Speaker 1: at the Big Bang. We're going all the way back

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Speaker 1: to the beginning. That's right. We want to understand everything

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Speaker 1: about the universe from the way it is today to

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Speaker 1: the way it started. Yeah. So we have awesome questions here,

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Speaker 1: and the first few are from a couple of kids

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Speaker 1: who listen to the podcast, and they have questions about

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Speaker 1: kind of our immediate neighborhood. So the first one is

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Speaker 1: from Kendall, who is seven years old. Hi, my name

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Speaker 1: is Kendall. I'm seven years old. I would like to

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Speaker 1: know why our stars so hot? Or hey you're a star,

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Speaker 1: why are you so hot? I don't know. You know,

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Speaker 1: I work out, I eat well, a mom cartoonists. I

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Speaker 1: think that adds to that air of you know, attractiveness. Yeah,

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Speaker 1: so great, another piece of life advice from somebody who

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Speaker 1: doesn't live a typical life. That's right, someone who doesn't

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Speaker 1: leave their house very much. But thank you Kendall for

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Speaker 1: sending in this question. That's awesome. That you're curious about

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Speaker 1: the Sun, about stars, about what's out there in space.

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Speaker 1: That's amazing And it's a great question because it sounds

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Speaker 1: like a simple question on the surface but actually gets

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Speaker 1: into a lot of really interesting physics. And it's not

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Speaker 1: that simple a question to answer. WHOA see, Kendall, you

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Speaker 1: just dumped the footy seven year old physicists. So Kendall's

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Speaker 1: question is why our stars so hot? I guess star

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Speaker 1: are pretty hot? Right, They're not cold. Stars are pretty hot.

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Speaker 1: The reason we can see them is because they're so hot. Remember,

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Speaker 1: everything in the universe glows, and the frequency at which

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Speaker 1: it glows depends on its temperature. So the Sun is

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Speaker 1: hot enough to glow in the visible spectrum, which is

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Speaker 1: pretty cool or pretty hot. Well, it's interesting because I

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Speaker 1: guess you know, maybe people your age and mind associate

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Speaker 1: light and something bright is something being hot, right, because

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Speaker 1: light bulbs are hot. You don't want to touch a

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Speaker 1: light bulb from from when we came from. But nowadays,

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Speaker 1: you know, with LED lights you can have like cool lights, right,

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Speaker 1: you can have a cold light bulb. Yeah, because the

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Speaker 1: light generated by an LED is not like black body radiation,

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Speaker 1: the way light from like a tungsten filament is it

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Speaker 1: comes from a quantum mechanical process, which is pretty super cool.

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Speaker 1: But one of the interesting things about stars is that

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Speaker 1: they are hot, but in order for them to even

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Speaker 1: get formed, they have to actually start out very, very cold.

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Speaker 1: So they have a really interesting sort of thermal history

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Speaker 1: to them, right, right, because I guess all star us

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Speaker 1: out there in space in the universe started off as

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Speaker 1: cold clouds of gas, right, That's how they all started. Like,

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Speaker 1: the gas isn't hot, it's just like it's just floating

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Speaker 1: out there in space, and space is really cold, so

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Speaker 1: really it comes from cold gas. It comes from cold gas.

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Speaker 1: And if you have a big cloud of gas, if

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Speaker 1: it starts out too hot, it can't form stars because

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Speaker 1: remember stars are formed by gravity pulling together all these

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Speaker 1: little bits of stuff. But gravity is super duper weak.

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Speaker 1: So for gravity to succeed pulling together a big cloud

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Speaker 1: of gas, it can't be too hot. If it's too hot,

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Speaker 1: it'll just ignore the gravity. So cloud has to cool

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Speaker 1: down enough for gravity to be able to take over

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Speaker 1: and compress it. And so if a cloud is more

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Speaker 1: than like ten or twenty degrees kelvin, it just can't

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Speaker 1: form stars. So a star starts off as cold gas,

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Speaker 1: and then gravity makes it all sort of clump together

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Speaker 1: into one kind of smaller ball of super hot gas exactly,

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Speaker 1: And it's that gravitational pressure that provides the heat. A

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Speaker 1: lot of people think that stars are hot because they

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Speaker 1: have fusion going on, because they are burning, but it's

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Speaker 1: the other way around. Stars get hot from gravity and

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Speaker 1: that temperature allows fusion to happen, and then the fusion

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Speaker 1: sustains them. But the reason that they're hot is that

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Speaker 1: gravity takes the gas and squeezes it into a smaller

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Speaker 1: space and that heats up the gas. Just maybe step

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Speaker 1: us through a little bit, because that's kind of a

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Speaker 1: tricky step. Like when you start off with a big

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Speaker 1: cold cloud of gas, well, why does crunching it together

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Speaker 1: make it hotter. It's an interesting bit of chemistry, right,

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Speaker 1: If you compress something, you make it hotter. And that

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Speaker 1: feels weird because you're like, hold on a second, it's

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Speaker 1: the same amount of stuff. I'm not doing anything. I'm

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Speaker 1: just squeezing it down. You're just like storing it closer together. Yeah,

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Speaker 1: it feels counterintuitive to think about it getting hotter, and

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Speaker 1: it's helpful to think about the temperature of that gas

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Speaker 1: as like the speed of the molecules of gas flying

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Speaker 1: around in it. Temperatures are really complicated topping. We have

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Speaker 1: a whole podcast about just that. But a simple way

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Speaker 1: to think about it is that a temperature is like

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Speaker 1: a spedometer of the particles in a gas. So a

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Speaker 1: hotter gas means particles moving faster, and a colder gas

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Speaker 1: means particles moving more slowly. So when when you take

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Speaker 1: a big cloud of gas and you squeeze it together,

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Speaker 1: somehow that makes the molecules, the little gas particles inside

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Speaker 1: in the in the cloud move faster exactly because what

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Speaker 1: you're doing when you squeeze it is that you're pushing

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Speaker 1: in on it. You're providing energy. You're actually putting energy

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Speaker 1: into that gas by squeezing it down. Think about, for example,

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Speaker 1: throwing a tennis ball against the wall. It comes back

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Speaker 1: at the same speed as you threw it. Cool, But

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Speaker 1: what if you threw a tennis ball against the front

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Speaker 1: of a train, Then when it comes back it would

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Speaker 1: be going faster. So if you're a tennis ball inside

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Speaker 1: a box and that box is shrinking, then every time

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Speaker 1: you hit the wall, you're gonna bounce off with more energy,

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Speaker 1: and so very gradually, as the box gets compressed, the

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Speaker 1: balls start moving faster and faster and they have a

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Speaker 1: higher temperature. Interesting. Now, just to be clear, candles seven

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Speaker 1: year old should not be throwing balls in front of

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Speaker 1: moving train. Right, that's a parenting question. I'm not going

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Speaker 1: to step in because I don't have realistic life advice.

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Speaker 1: That's right as your parents first, always for all things.

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Speaker 1: But that's interesting, and that's an interesting analogy. Like if

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Speaker 1: the walls are closing in on you, they're going to

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Speaker 1: be imparting some energy on the balls hitting the walls.

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Speaker 1: But I guess in space there's there are no walls.

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Speaker 1: It's just gravity moving things together. So where does that

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Speaker 1: extra energy come from? Right? Well, gravity is pulling stuff together,

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Speaker 1: and the way it creates more pressure is that it's

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Speaker 1: like pulling gas on the outside of you in you know,

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Speaker 1: So the wall is like the next layer of gas,

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Speaker 1: which is less and less pressure, but effectively it acts

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Speaker 1: like a wall. So gravity is pulling everything and it

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Speaker 1: creates this gravitational well which makes it harder for the

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Speaker 1: particles to leave. So each shell of gas is sort

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Speaker 1: of compressing the next shell of gas. Interesting, all right,

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Speaker 1: so then you have a big cold cloud of gas

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Speaker 1: that gets compressed. Then that gets hot, and at some

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Speaker 1: point it gets so hot it starts to explode in

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Speaker 1: the middle. Yeah, if when it reaches like twelve million

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Speaker 1: degrees kelvin internally, it can start to fuse hydrogen into

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Speaker 1: helium and that releases a bunch of energy, and that

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Speaker 1: helps us start stay hot and actually also EAPs the

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Speaker 1: star from collapsing further. If you just let gravity do

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Speaker 1: its thing, it would turn those particles into a black hole.

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Speaker 1: But fusion pushes back, and then you get this balance

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Speaker 1: between the energy released from fusion, the outward pressure and

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Speaker 1: the inward pressure of gravity, and the star burns for

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Speaker 1: a few million, billion or trillion years, depending on its size.

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Speaker 1: I see. So then I guess the answer to Kendall's

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Speaker 1: question is that stars are hot because they can't have

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Speaker 1: to be Otherwise you won't have a star, Like you

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Speaker 1: can't have a cold star, right, You can't have a

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Speaker 1: cold star unless you call it black dwarf, a star

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Speaker 1: which is a remnant from a white dwarf that has

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Speaker 1: cooled off. But yeah, you can't have a cold star.

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Speaker 1: So I guess by definition, right, a star is something

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Speaker 1: that is hot. But I think the most direct answer

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Speaker 1: to this question is that gravity is what makes a

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Speaker 1: star hot to begin with. It ignites the star and

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Speaker 1: then fusion keeps it hot. Yeah, because I guess you know,

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Speaker 1: once gravity crunches everything together, it will stay hot even

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Speaker 1: if there's no fusion, right, true, But if there was

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Speaker 1: no fusion, it would compress into a black hole. And

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Speaker 1: then you get me into questions of like what's the

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Speaker 1: temperature of a black hole? That that's the subject of

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Speaker 1: another podcast. That's a whole rabbit hole. All right, Well,

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Speaker 1: thank you Kendall. Hope that answered the question. And so

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Speaker 1: we have another question from Megan who's ten years old,

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Speaker 1: who is a question about the moon. How my name's Megan,

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Speaker 1: and I'm wondering why they are craters on the moon. Yeah,

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Speaker 1: why are there creators on the moon? Like if you

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Speaker 1: look at the moon, great question, Megan. By the way

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Speaker 1: you look at the moon, it's not like a perfect

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Speaker 1: little sephee or perfect circle. It's not just all one

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Speaker 1: color or one um, one smooth surfer that it has

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Speaker 1: a bunch of holes and pop marks in it. Right, Yeah,

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Speaker 1: there are a lot of craters on the moon. By

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Speaker 1: last count there are nine thousand, one d and thirties

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Speaker 1: seven recognized creators with names nine that's a lot. I

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Speaker 1: have a friend who did her PhD in like moon craters,

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Speaker 1: Like she was in a moon crater when she did

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Speaker 1: her PhD that time. Yeah, suddenly she became a lot cooler.

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Speaker 1: You're right, Yeah, Yeah, there are a lot of these craters,

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Speaker 1: and it's fascinating because you look at the Moon you're like, Wow,

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Speaker 1: the Moon is filled with creators, but the error there

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Speaker 1: is not. And so that's an interesting question. Yeah, we

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Speaker 1: don't have like giants holes here north, at least not

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Speaker 1: not that are visible. And it's not a question we

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Speaker 1: actually knew the answer to. Until we went to the Moon.

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Speaker 1: This was an open question about the source of these craters.

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Speaker 1: Some people thought maybe there was like volcanic activity on

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Speaker 1: the Moon and each crater was like a little mini volcano,

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Speaker 1: and other people thought they were impact from rocks from

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Speaker 1: space and there they were even crazier ideas. And until

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Speaker 1: we went to the Moon and got samples and studied

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Speaker 1: the age of the surface, we didn't know the answer

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Speaker 1: to Megan's question. Interesting, Yeah, they could have been like

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Speaker 1: holes on a piece of cheese. Was that your friend's

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Speaker 1: thesis topic on the lore of the moon cheese hypothesis. Well,

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Speaker 1: now we know that the surface of the Moon is

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Speaker 1: about as old as the surface of the Earth, about

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Speaker 1: four and a half billion years old. But the Moon,

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Speaker 1: unlike the Earth, doesn't have an atmosphere, right, doesn't have

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Speaker 1: like a cloud of gas surrounding it. And so the

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Speaker 1: short answer to Megan's question is that it's rocks from space.

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Speaker 1: Space is filled with rocks that are constantly hitting everything

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Speaker 1: in the Solar System. And if you have a shield

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Speaker 1: like the Earth does, and most of those don't hit

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Speaker 1: the ground, But the Moon doesn't have a shield, and

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Speaker 1: so it gets smacked by every rock that comes its way. Yeah,

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Speaker 1: and it's kind of interesting to think like that happened

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Speaker 1: or is happening all over the Solar System, right, Like

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Speaker 1: there are planets who also don't have an atmosphere who

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Speaker 1: are filled with craters too. Yeah, Basically every surface on

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Speaker 1: the Solar System will get impacted with craters, and so

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Speaker 1: you need some kind of protection if you're going to

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Speaker 1: live there, either an atmosphere or like a really strong umbrella.

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Speaker 1: All right, So to answer Megan's question, the Moon has

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Speaker 1: craters because it gets hit by a lot of rocks

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Speaker 1: from space and it doesn't have a coating of air

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Speaker 1: to kind of protect it. Yeah, and some of these

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Speaker 1: craters are like more than two billion years old. No

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Speaker 1: wind or water on the Moon, so if you form

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Speaker 1: a crater, it will last a very very long time.

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Speaker 1: There's one crater on the Moon that might even be

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Speaker 1: four billion years old, and scientists think that an asteroid

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Speaker 1: more than a hundred d miles across smashed into it

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Speaker 1: about four billion years ago, such a big explosion. It

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Speaker 1: probably rain did debris down on the surface of the Earth.

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Speaker 1: Interesting Also, I think another part of the answer is

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Speaker 1: that there's no lava on the Moon, right Like we

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Speaker 1: have lava here on Earth and that's kind of making

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Speaker 1: the surface move a lot, which kind of gets rid

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Speaker 1: of all of the craters that we used to have.

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Speaker 1: But in the Moon there's no lava, so it does

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Speaker 1: nothing ever moved. And the surface of the Moon really

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Speaker 1: interestingly is covered in this like really fine grain soil.

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Speaker 1: If you look at the astronauts footsteps, for example, you

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Speaker 1: know that they were walking through like several centimeters of

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Speaker 1: what looks like dust, and this lunar dust. It basically

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Speaker 1: the shattered surface. There's been so many impacts on the

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Speaker 1: Moon that its surface is basically covered with shattered little

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Speaker 1: pieces of rock. I guess the question is, like, are

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Speaker 1: there still new craters being formed in the Moon? Like

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Speaker 1: does the Solar system now have fewer asteroids flying around

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Speaker 1: or are there still is the Moon still getting bombarded

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Speaker 1: by meteors. It's still getting bombarded. We actually we saw

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Speaker 1: one happen in two thousand and thirteen which was visible

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Speaker 1: to the naked eye. A nine pound meteoroid strike the

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Speaker 1: surface at like nine thousand kilometers per hour and left

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Speaker 1: a new crater. So it's still happening. Wow, But is

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Speaker 1: it happening faster or at the same rate as before

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Speaker 1: or has the Solar system sort of calmed down a

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Speaker 1: little bit? The Solar system definitely has calmed down. In

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Speaker 1: the very early part of the history of the Solar System,

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Speaker 1: there was the heavy bombardment period when the Solar System

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Speaker 1: was a huge mess. Since then, things have calmed down

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Speaker 1: and larger objects have pulled together to make fewer objects.

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Speaker 1: Since you have fewer rocks out there than you used

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Speaker 1: to see. Yeah, we've made it past purity, right, skin

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Speaker 1: is now going to clear up a little bit more.

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Speaker 1: All right, well, thank you Kendall and Megan for these

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Speaker 1: awesome questions. We hope you keep asking questions, and so

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Speaker 1: now let's get to our other questions about asteroids that

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Speaker 1: might kill us here on Earth and also about the

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Speaker 1: nature of matter and energy. But first let's take a

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Speaker 1: quick break. All right, we are answering questions from listeners,

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Speaker 1: and we've just answered some awesome questions about the stars

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Speaker 1: in our in the moon, and so now let's get

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Speaker 1: into some terior topics like the possible extinction of humankind. Hi,

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Speaker 1: Dani and Jorge, this is Shawn calling from Ottawa, Ontario, Canada.

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Speaker 1: We always hear about asteroids and comets hitting the Earth

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Speaker 1: at thousands of kilometers per second and wiping out life

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Speaker 1: as we know it. But I was wondering, is it

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Speaker 1: possible for a comet or an asteroid two come in

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Speaker 1: and slowly hit the Earth where it won't kill us all?

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Speaker 1: Maybe if we're both on the same trajectory and it

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Speaker 1: can come in and just gently land somewhere on Earth

427
00:21:54,920 --> 00:21:58,639
Speaker 1: and not destroy everything. Anyways, thanks for the great podcast.

428
00:21:59,400 --> 00:22:02,760
Speaker 1: All right, some question, thank you, Sean. It's an interesting question, Yeah,

429
00:22:02,800 --> 00:22:05,440
Speaker 1: because I guess when you think of asteroids hitting the Earth,

430
00:22:05,520 --> 00:22:08,520
Speaker 1: you usually think of them as coming in fast and

431
00:22:08,640 --> 00:22:11,600
Speaker 1: crashing on Earth. But he's asking, you know, could one

432
00:22:11,800 --> 00:22:14,720
Speaker 1: somehow sort of like creep up on us and kind

433
00:22:14,760 --> 00:22:18,960
Speaker 1: of shem me onto our planet and gently, you know,

434
00:22:19,200 --> 00:22:21,480
Speaker 1: land in the middle of the ocean or something. Yeah,

435
00:22:21,480 --> 00:22:24,240
Speaker 1: it's very Canadian. He's looking for like a friendly asteroid

436
00:22:24,240 --> 00:22:29,880
Speaker 1: that just comes and settles down gently. But yeah, maybe

437
00:22:29,920 --> 00:22:33,520
Speaker 1: the land in Canada and apologize for causing a disturbance.

438
00:22:33,840 --> 00:22:35,600
Speaker 1: It is an awesome question. Why do we always think

439
00:22:35,600 --> 00:22:39,040
Speaker 1: about asteroids? It's basically like bullets aimed at the Earth.

440
00:22:39,840 --> 00:22:42,240
Speaker 1: Can't we think about them like moving in parallel to

441
00:22:42,280 --> 00:22:45,200
Speaker 1: the Earth and very gently coming into the surface. It's

442
00:22:45,200 --> 00:22:48,520
Speaker 1: a really cool question. I guess, um, it maybe seems

443
00:22:48,600 --> 00:22:50,760
Speaker 1: unlikely that something would just come out of the blue

444
00:22:50,960 --> 00:22:54,119
Speaker 1: and then just happened to like fly right next to

445
00:22:54,200 --> 00:22:57,399
Speaker 1: us slowly, And that's the answer. It is possible, but

446
00:22:57,520 --> 00:23:00,840
Speaker 1: it's much less likely if you just pick like random

447
00:23:00,880 --> 00:23:03,480
Speaker 1: trajectories for rocks in space that are going to come

448
00:23:03,480 --> 00:23:05,800
Speaker 1: into contact with the Earth. It's just much easier for

449
00:23:05,840 --> 00:23:08,439
Speaker 1: those rocks to be going the opposite direction of the

450
00:23:08,480 --> 00:23:11,320
Speaker 1: Earth or to be going in opposite direction of the Earth.

451
00:23:11,520 --> 00:23:15,040
Speaker 1: At least at some level. It's possible for a rock

452
00:23:15,200 --> 00:23:18,040
Speaker 1: from the asteroid belt or the Kuiper Belt or even

453
00:23:18,040 --> 00:23:20,960
Speaker 1: the Orc Cloud to end up in like the Earth's orbit,

454
00:23:21,280 --> 00:23:24,120
Speaker 1: but it would take a very special circumstance. You mean,

455
00:23:24,160 --> 00:23:26,280
Speaker 1: like it is possible maybe for one of the asteroids

456
00:23:26,320 --> 00:23:28,920
Speaker 1: around us to like suddenly kind of jump into our orbit.

457
00:23:29,080 --> 00:23:31,200
Speaker 1: It is possible, But everything right now in the Solar

458
00:23:31,200 --> 00:23:33,679
Speaker 1: System hasn't orbit. The reason it's still around is that

459
00:23:33,720 --> 00:23:36,320
Speaker 1: it hasn't fallen into the Sun. It's in some orbit.

460
00:23:36,400 --> 00:23:38,840
Speaker 1: So even to come into contact with the Earth would

461
00:23:38,880 --> 00:23:41,720
Speaker 1: require it most likely to change its orbit. The collision

462
00:23:41,760 --> 00:23:44,639
Speaker 1: happens when the trajectory of one of those objects intersects

463
00:23:44,640 --> 00:23:47,200
Speaker 1: with the Earth right, which is very unlikely to happen

464
00:23:47,560 --> 00:23:49,760
Speaker 1: in parallel. In order for one of those things to

465
00:23:49,840 --> 00:23:51,919
Speaker 1: like jump into the Earth's orbit, it would need to

466
00:23:52,040 --> 00:23:55,359
Speaker 1: change its trajectory, which means like hitting something else and

467
00:23:55,520 --> 00:23:58,200
Speaker 1: bouncing off. So you need like two things to come

468
00:23:58,240 --> 00:24:00,879
Speaker 1: into contact and change each other orbits that one of

469
00:24:00,920 --> 00:24:03,800
Speaker 1: them happens to end up in Earth's orbit and kind

470
00:24:03,800 --> 00:24:06,280
Speaker 1: of going at the same speed. But I guess couldn't

471
00:24:06,280 --> 00:24:09,440
Speaker 1: it also happened that the Earth, you know, maybe passes

472
00:24:09,560 --> 00:24:12,440
Speaker 1: by close enough to a cloud of asteroids that maybe

473
00:24:12,480 --> 00:24:15,480
Speaker 1: like pulls one along with our gravity. Yeah, that is possible.

474
00:24:15,520 --> 00:24:17,000
Speaker 1: And in fact, there are some things out there that

475
00:24:17,040 --> 00:24:19,639
Speaker 1: have been sort of like captured by the Earth. They

476
00:24:19,640 --> 00:24:22,320
Speaker 1: haven't landed on the Earth when they came close enough

477
00:24:22,359 --> 00:24:24,919
Speaker 1: to the Earth that sort of now in orbit around

478
00:24:25,000 --> 00:24:28,160
Speaker 1: the Earth or sharing the Earth's orbit around the Sun.

479
00:24:28,240 --> 00:24:30,760
Speaker 1: At least one of these things is called the space

480
00:24:30,840 --> 00:24:34,159
Speaker 1: being because it traces out this weird path relative to

481
00:24:34,200 --> 00:24:37,280
Speaker 1: the Earth. It's this five kilometer diameter rock where there

482
00:24:37,400 --> 00:24:39,280
Speaker 1: is a rock like that that it has somehow fallen

483
00:24:39,359 --> 00:24:41,280
Speaker 1: into our orbit and it is kind of going along

484
00:24:41,320 --> 00:24:44,439
Speaker 1: with us. Yeah, officially, it's like a quasi satellite of

485
00:24:44,480 --> 00:24:46,880
Speaker 1: the Earth. It's got a fancy name which I can pronounce,

486
00:24:46,880 --> 00:24:49,200
Speaker 1: and it has its own elliptical orbit around the Sun

487
00:24:49,400 --> 00:24:52,320
Speaker 1: that's sort of in residence with the Earth's and so

488
00:24:52,440 --> 00:24:55,560
Speaker 1: from our perspective, it has this like weird being shaped

489
00:24:55,640 --> 00:24:58,800
Speaker 1: orbit around the Earth. But effectively it's been captured and

490
00:24:58,960 --> 00:25:01,119
Speaker 1: in a very similar or bit to the Earth. But

491
00:25:01,280 --> 00:25:04,200
Speaker 1: of course it's not landing on our surface, right right,

492
00:25:04,200 --> 00:25:06,800
Speaker 1: but it's interesting that it's possible, right, Like, what maybe

493
00:25:06,840 --> 00:25:09,000
Speaker 1: can happen again and we could pick up another bean. Well,

494
00:25:09,000 --> 00:25:11,359
Speaker 1: this one, the closest it ever comes is like seven

495
00:25:11,400 --> 00:25:14,200
Speaker 1: and a half million miles from the surface of the Earth,

496
00:25:14,240 --> 00:25:17,520
Speaker 1: which is like thirty times further than the Moon. I see,

497
00:25:17,680 --> 00:25:20,480
Speaker 1: I see, But maybe it eventually, could it somehow, you know,

498
00:25:20,600 --> 00:25:24,080
Speaker 1: creep into the Earth, Like maybe not now, maybe, but

499
00:25:24,160 --> 00:25:26,879
Speaker 1: maybe in a million years, could it somehow, you know,

500
00:25:27,200 --> 00:25:29,320
Speaker 1: start creeping in and maybe go into orbit around the

501
00:25:29,320 --> 00:25:32,320
Speaker 1: Earth at some point. It's certainly possible, right if it

502
00:25:32,359 --> 00:25:35,080
Speaker 1: impacts something or something else comes along and tugs on it,

503
00:25:35,080 --> 00:25:37,639
Speaker 1: it could change its orbit. And it is possible for

504
00:25:37,960 --> 00:25:40,680
Speaker 1: something to get even closer to the Earth and eventually

505
00:25:40,960 --> 00:25:43,520
Speaker 1: even come into the atmosphere. And in theory it could

506
00:25:43,520 --> 00:25:49,200
Speaker 1: come in slowly, could like gently approach the Earth's atmosphere. Interesting, Well,

507
00:25:49,520 --> 00:25:51,679
Speaker 1: you said it's not very likely because I guess we

508
00:25:51,760 --> 00:25:55,080
Speaker 1: have most asteroids out there kind of catalog, So I

509
00:25:55,080 --> 00:25:58,240
Speaker 1: imagine if any do sort of surprises, it's they're going

510
00:25:58,280 --> 00:26:00,360
Speaker 1: to be coming in pretty fast. But maybe, just for fun,

511
00:26:00,440 --> 00:26:03,480
Speaker 1: let's assumed that um Seawan scenario here comes through in

512
00:26:04,000 --> 00:26:07,040
Speaker 1: which is like make an asteroid appear right next to Earth,

513
00:26:07,840 --> 00:26:09,879
Speaker 1: we would it kills or would it's just kind of

514
00:26:10,040 --> 00:26:11,719
Speaker 1: gently bump us. Yeah, I just want to make one

515
00:26:11,760 --> 00:26:13,560
Speaker 1: more comment and the likelihood of it. Another way to

516
00:26:13,560 --> 00:26:15,960
Speaker 1: think about why it's unlikely is that these objects are

517
00:26:16,000 --> 00:26:19,200
Speaker 1: moving typically faster than the Earth. You know, the Earth

518
00:26:19,240 --> 00:26:22,119
Speaker 1: moves like thirty kilos per second around the Sun, and

519
00:26:22,160 --> 00:26:25,600
Speaker 1: these asteroids moved like fortify or even faster if their

520
00:26:25,640 --> 00:26:27,920
Speaker 1: comments from the outer Solar System. And if you think

521
00:26:27,920 --> 00:26:31,399
Speaker 1: about like two velocity vectors, in order for one of

522
00:26:31,400 --> 00:26:33,159
Speaker 1: these to catch the Earth, they basically have to be

523
00:26:33,240 --> 00:26:36,840
Speaker 1: perfectly aligned with the Earth. Otherwise to impact they could

524
00:26:36,840 --> 00:26:39,640
Speaker 1: have at any angle. So it's just unlikely for these

525
00:26:39,640 --> 00:26:42,199
Speaker 1: things to be perfectly aligned with the Earth's direction. But

526
00:26:42,240 --> 00:26:44,160
Speaker 1: you ask a great question, like what would happen if

527
00:26:44,160 --> 00:26:47,159
Speaker 1: this thing like gently came up to the Earth's atmosphere?

528
00:26:47,240 --> 00:26:50,240
Speaker 1: Would that actually hurt us? And I like Shaun's fantasy

529
00:26:50,280 --> 00:26:52,439
Speaker 1: that this thing would like gently sink down to the

530
00:26:52,440 --> 00:26:54,080
Speaker 1: surface of the Earth so we could like you know,

531
00:26:54,280 --> 00:26:56,359
Speaker 1: touch it and build a monument to it or whatever,

532
00:26:56,600 --> 00:26:58,760
Speaker 1: But actually I don't think that's likely either. I guess

533
00:26:58,760 --> 00:27:00,439
Speaker 1: maybe let's paint the picture a little it better. So

534
00:27:00,680 --> 00:27:04,359
Speaker 1: the Earth is moving through space, We're spinning, and somehow

535
00:27:04,480 --> 00:27:07,359
Speaker 1: like another an esteroid kind of like chemis up to us,

536
00:27:07,560 --> 00:27:09,640
Speaker 1: going at the same speed, in the same direction, maybe

537
00:27:09,640 --> 00:27:11,960
Speaker 1: in the same orbit, and then just a little by little,

538
00:27:12,040 --> 00:27:14,880
Speaker 1: just kind of bumps into the Earth. Is that possible.

539
00:27:14,960 --> 00:27:16,680
Speaker 1: It's possible for it to get close to the Earth

540
00:27:16,720 --> 00:27:18,440
Speaker 1: and like join our orbit, but then it's going to

541
00:27:18,520 --> 00:27:20,440
Speaker 1: be captured by the Earth and it's going to fall

542
00:27:20,520 --> 00:27:24,080
Speaker 1: into the Earth's gravitational Well, remember the Earth itself has

543
00:27:24,119 --> 00:27:26,520
Speaker 1: a lot of gravity. So if you just like dropped

544
00:27:26,520 --> 00:27:29,320
Speaker 1: a big rock at zero velocity at the top of

545
00:27:29,359 --> 00:27:32,560
Speaker 1: the atmosphere, what would happen, Well, the Earth would pull

546
00:27:32,600 --> 00:27:34,560
Speaker 1: on it. By the time it reached the surface, it

547
00:27:34,560 --> 00:27:37,960
Speaker 1: would have a lot of kinetic energy. Imagine what would

548
00:27:37,960 --> 00:27:40,200
Speaker 1: happen if you drop like a penny from the top

549
00:27:40,240 --> 00:27:43,080
Speaker 1: of the atmosphere. It would be going super duper fast

550
00:27:43,160 --> 00:27:44,840
Speaker 1: by the time I hit the ground. Oh, I see

551
00:27:44,840 --> 00:27:47,840
Speaker 1: you're seeing. Like, even if I parked this esteroid close

552
00:27:47,920 --> 00:27:50,720
Speaker 1: to us, just the earth gravity is gonna pull it

553
00:27:50,720 --> 00:27:53,359
Speaker 1: in and make it go faster towards us. Yeah, the

554
00:27:53,480 --> 00:27:57,600
Speaker 1: escape velocity of the Earth he's like eleven kilometers per second,

555
00:27:57,720 --> 00:27:59,320
Speaker 1: And so that means if you're going at like zero

556
00:27:59,359 --> 00:28:02,280
Speaker 1: kilometers per second at the top of the atmosphere, then

557
00:28:02,359 --> 00:28:04,280
Speaker 1: by the time you get to the bottom, you're gonna

558
00:28:04,280 --> 00:28:06,719
Speaker 1: be going in eleven kilometers per second. So it's a

559
00:28:06,720 --> 00:28:09,720
Speaker 1: lot of kinetic energy, right. But I guess maybe Shawn's

560
00:28:09,800 --> 00:28:11,800
Speaker 1: point was that, you know, even if it's going at

561
00:28:11,800 --> 00:28:15,120
Speaker 1: eleven kilometers per second, that's still not as fast as

562
00:28:15,160 --> 00:28:18,000
Speaker 1: most asteroids that hit Earth are going. And so maybe

563
00:28:18,000 --> 00:28:20,760
Speaker 1: it would he's saying it would. Would it might survive

564
00:28:20,920 --> 00:28:23,439
Speaker 1: the atmosphere, right, not get burned up by all the

565
00:28:23,480 --> 00:28:27,360
Speaker 1: friction from the error, and maybe it might it will

566
00:28:27,840 --> 00:28:30,000
Speaker 1: crash onto Earth, Yeah, and I think that's likely that

567
00:28:30,040 --> 00:28:31,720
Speaker 1: it would make it to the surface of the Earth.

568
00:28:31,760 --> 00:28:33,800
Speaker 1: You know, it wouldn't actually get to eleven kilometers per

569
00:28:33,800 --> 00:28:35,439
Speaker 1: second by the time it hits the Earth because of

570
00:28:35,480 --> 00:28:37,919
Speaker 1: the resistance from the air. It would heat up and

571
00:28:38,200 --> 00:28:40,640
Speaker 1: parts of it would blow off. But probably it would survive,

572
00:28:40,720 --> 00:28:42,840
Speaker 1: but it might make a crater when it lands because

573
00:28:42,840 --> 00:28:45,280
Speaker 1: it would be going pretty fast. But even asteroids that

574
00:28:45,360 --> 00:28:47,160
Speaker 1: do hit the Earth at high speed, some of them

575
00:28:47,600 --> 00:28:49,720
Speaker 1: make it to the surface. If they're big enough to

576
00:28:49,800 --> 00:28:53,120
Speaker 1: survive the trip through the atmosphere. Interesting, I guess maybe

577
00:28:53,120 --> 00:28:56,560
Speaker 1: then the real answer to Shaun's question of couldn't asteroid

578
00:28:56,600 --> 00:28:59,920
Speaker 1: hits slowly without killing us? The answer is not, because

579
00:29:00,000 --> 00:29:03,680
Speaker 1: and a story can hit its slowly. Any asteroid that

580
00:29:03,800 --> 00:29:05,880
Speaker 1: hits is going to be coming in pretty fast because

581
00:29:05,880 --> 00:29:08,680
Speaker 1: the Earth's gravity pulls it in and it's going to

582
00:29:08,880 --> 00:29:11,760
Speaker 1: pick up speed. You might imagine another scenario where a

583
00:29:11,840 --> 00:29:13,880
Speaker 1: rock comes in near the Earth and it has like

584
00:29:14,040 --> 00:29:16,800
Speaker 1: negative velocity, like the Earth is catching up to it,

585
00:29:16,840 --> 00:29:20,080
Speaker 1: but it's running away in the atmosphere gradually slows it

586
00:29:20,120 --> 00:29:23,720
Speaker 1: down so it lands on Earth. But that's even more unlikely.

587
00:29:23,880 --> 00:29:26,480
Speaker 1: The Earth would have to like sneak up on this rock, right.

588
00:29:26,480 --> 00:29:29,479
Speaker 1: It's it's less likely, but much cooler to think about.

589
00:29:30,520 --> 00:29:32,560
Speaker 1: So you're saying that there could be an asteroids flying

590
00:29:32,560 --> 00:29:35,120
Speaker 1: through space sort of in our orbit, and so Earth

591
00:29:35,280 --> 00:29:38,920
Speaker 1: sort of sneak like we sneak up behind it, and

592
00:29:39,000 --> 00:29:41,080
Speaker 1: we're in such a trajectory, and it's in such a

593
00:29:41,080 --> 00:29:44,479
Speaker 1: trajectory that it really just kind of slowly touches us.

594
00:29:44,680 --> 00:29:47,400
Speaker 1: So what you're saying, Yeah, I think that's probably possible.

595
00:29:47,480 --> 00:29:49,440
Speaker 1: I haven't run the simulation, but you'd have to have

596
00:29:49,600 --> 00:29:52,880
Speaker 1: a lot of factors exactly a line to make that work.

597
00:29:53,080 --> 00:29:55,280
Speaker 1: Like what's the slowest it could hit Earth? You know

598
00:29:55,320 --> 00:29:57,520
Speaker 1: what I mean? Like would it still pick up eleven

599
00:29:57,560 --> 00:30:00,760
Speaker 1: kilombers per second? Or is there a snario in which

600
00:30:00,800 --> 00:30:04,760
Speaker 1: it literally like just slowly kind of touches the Earth. Well,

601
00:30:04,800 --> 00:30:07,280
Speaker 1: there's some things you have to balance there, because in

602
00:30:07,400 --> 00:30:09,880
Speaker 1: order for it to be going slower when it hits

603
00:30:09,920 --> 00:30:12,680
Speaker 1: the Earth, you wanted to start with like negative velocity

604
00:30:12,760 --> 00:30:15,520
Speaker 1: velocity away from the Earth at the top of the atmosphere.

605
00:30:15,560 --> 00:30:17,040
Speaker 1: But then you know, how is it getting to the

606
00:30:17,080 --> 00:30:19,800
Speaker 1: top of the atmosphere. It has velocity away from the Earth,

607
00:30:20,240 --> 00:30:22,320
Speaker 1: so it can't be going too fast away from the Earth.

608
00:30:22,360 --> 00:30:25,160
Speaker 1: The Earth has like sneak up behind it while it's

609
00:30:25,200 --> 00:30:28,120
Speaker 1: moving fast away from the Earth, and then the atmosphere

610
00:30:28,240 --> 00:30:31,080
Speaker 1: somehow slows it down and pulls it in. So it's

611
00:30:31,120 --> 00:30:34,000
Speaker 1: a pretty tricky set of circumstances. But I bet it's

612
00:30:34,040 --> 00:30:36,520
Speaker 1: technically possible, and you know, if the solar systems around

613
00:30:36,520 --> 00:30:39,000
Speaker 1: for long enough, maybe it will happen. Right right, just

614
00:30:39,040 --> 00:30:41,560
Speaker 1: got to the mass, right, Anything is possible with them,

615
00:30:42,320 --> 00:30:44,960
Speaker 1: But are you envisioning that this could like literally just

616
00:30:45,000 --> 00:30:47,680
Speaker 1: like touch down like a spaceship or would it crash

617
00:30:47,760 --> 00:30:50,760
Speaker 1: land anyways, just because you know the guy is big

618
00:30:50,800 --> 00:30:52,760
Speaker 1: and it's going to fall. Well, the slower you wanted

619
00:30:52,800 --> 00:30:55,920
Speaker 1: to hit the Earth's surface, the less likely this scenario

620
00:30:56,120 --> 00:30:58,680
Speaker 1: is because the faster it has to be going away

621
00:30:58,720 --> 00:31:00,640
Speaker 1: from us at the top of the atmosphere. And I

622
00:31:00,640 --> 00:31:02,600
Speaker 1: think technically it might be possible for it to like

623
00:31:02,800 --> 00:31:05,880
Speaker 1: gradually sink into the Earth's atmosphere if it has enough

624
00:31:05,960 --> 00:31:09,400
Speaker 1: initial velocity away from us and the atmosphere just sort

625
00:31:09,400 --> 00:31:13,280
Speaker 1: of like slurps it in gradually. Interesting. That was pretty

626
00:31:13,320 --> 00:31:16,280
Speaker 1: cool to see a giant rock slowly land on Earth.

627
00:31:17,760 --> 00:31:19,880
Speaker 1: I don't expect that to happen. And after this, I'm

628
00:31:19,880 --> 00:31:21,560
Speaker 1: gonna have to go write some code to simulate this

629
00:31:21,680 --> 00:31:24,600
Speaker 1: too but actually work. But that's my instinct. All right,

630
00:31:24,720 --> 00:31:27,040
Speaker 1: let's stay tuned. Well that Daniel writes in a scientific

631
00:31:27,040 --> 00:31:30,240
Speaker 1: paper about it, and when it comes out, we'll we'll

632
00:31:30,280 --> 00:31:31,720
Speaker 1: let you know. That's right, and Sean will make you

633
00:31:31,720 --> 00:31:35,000
Speaker 1: a co author. Wow. Nice, See what can happened when

634
00:31:35,000 --> 00:31:38,000
Speaker 1: you write questions to us? You might become a physicist

635
00:31:38,000 --> 00:31:40,040
Speaker 1: for real? All right, Well, let's get into our last

636
00:31:40,080 --> 00:31:44,200
Speaker 1: question about the nature of matter and energy at the

637
00:31:44,200 --> 00:31:59,920
Speaker 1: Big Bank. But first let's take another quick break. All right,

638
00:32:00,000 --> 00:32:03,160
Speaker 1: we're answering listener questions, and we've answered questions from kids

639
00:32:03,200 --> 00:32:06,560
Speaker 1: about the sun and the moon, and also a question

640
00:32:07,160 --> 00:32:11,080
Speaker 1: about an asteroid slowly killing us slowly with its song

641
00:32:11,720 --> 00:32:15,400
Speaker 1: that with its a space song. I guess it's telling

642
00:32:15,440 --> 00:32:18,160
Speaker 1: our whole life with its trajectory. I guess that's that's

643
00:32:18,200 --> 00:32:20,320
Speaker 1: kind of a philosophical question. If an asteroid is going

644
00:32:20,400 --> 00:32:21,800
Speaker 1: to come and kills do you want it to be

645
00:32:21,880 --> 00:32:23,520
Speaker 1: fast or do you do you want it to be

646
00:32:23,560 --> 00:32:27,040
Speaker 1: slow and you want to see it coming. I definitely

647
00:32:27,040 --> 00:32:29,200
Speaker 1: want to see it coming so we can potentially divert

648
00:32:29,280 --> 00:32:33,480
Speaker 1: it so it doesn't come and kill us. What if,

649
00:32:33,520 --> 00:32:35,640
Speaker 1: like you do, see it's coming, but there's nothing we

650
00:32:35,640 --> 00:32:37,920
Speaker 1: can do about it. We always have Bruce willis Man,

651
00:32:39,880 --> 00:32:42,400
Speaker 1: did you see that latest movie with the Leonardo DiCaprio

652
00:32:42,960 --> 00:32:45,600
Speaker 1: and the asteroid don't look up? Yeah? Yeah, I did.

653
00:32:45,680 --> 00:32:47,400
Speaker 1: That was a lot of fun. I heard that he

654
00:32:47,440 --> 00:32:49,920
Speaker 1: couldn't write the equations himself on the board, so they

655
00:32:49,960 --> 00:32:52,800
Speaker 1: had to have a hand double doing the math close

656
00:32:52,920 --> 00:32:56,200
Speaker 1: ups for those shots. Whoa that could have been you, Daniel.

657
00:32:56,640 --> 00:32:59,840
Speaker 1: Now I have a new life, the real Leonard of

658
00:32:59,880 --> 00:33:04,600
Speaker 1: the Caprio's hand physics hand model. It's like being a

659
00:33:04,600 --> 00:33:08,080
Speaker 1: stuntman basically, it's just that dangerous, right right, Yeah, you

660
00:33:08,120 --> 00:33:11,640
Speaker 1: could get carpal tunnel from or I could become a

661
00:33:11,680 --> 00:33:13,560
Speaker 1: movie star and then I could brag and say I

662
00:33:13,640 --> 00:33:19,320
Speaker 1: do my own math. Well, let's see what happens first.

663
00:33:21,040 --> 00:33:23,400
Speaker 1: It's more likely that a huge rock will slowly touchdown

664
00:33:23,440 --> 00:33:27,240
Speaker 1: the atmosphere than at that any of that happens. Yeah,

665
00:33:27,360 --> 00:33:28,920
Speaker 1: I guess if you become a movie star that there

666
00:33:28,920 --> 00:33:33,120
Speaker 1: would be the end of the world. That's one of

667
00:33:33,160 --> 00:33:37,000
Speaker 1: the signs of the apocalypse, right there, Frogs falling from

668
00:33:37,000 --> 00:33:40,440
Speaker 1: this guy Daniel co starring in a movie with Leonardo DiCaprio,

669
00:33:40,640 --> 00:33:43,760
Speaker 1: although Neil de grass Tyson has been in big movies, right,

670
00:33:43,760 --> 00:33:46,040
Speaker 1: So it's possible there are physics out there that have

671
00:33:46,400 --> 00:33:48,600
Speaker 1: broken into Hollywood. Oh man, it is the end of

672
00:33:48,600 --> 00:33:51,840
Speaker 1: the world then. But anyways, we're answering listener questions and

673
00:33:51,880 --> 00:33:54,520
Speaker 1: our last question of the day comes from Jeels, who

674
00:33:54,560 --> 00:33:59,400
Speaker 1: has a question about which came first in the universe. Hello,

675
00:33:59,560 --> 00:34:03,640
Speaker 1: Danny on Jorge, how are you guys? My name's chill,

676
00:34:04,320 --> 00:34:08,600
Speaker 1: and I was curious about the following. I know that

677
00:34:09,000 --> 00:34:14,440
Speaker 1: matter and energy are intimately connected, but I was wondering

678
00:34:15,000 --> 00:34:19,839
Speaker 1: what came first matter or energy. I would appreciate if

679
00:34:19,880 --> 00:34:23,600
Speaker 1: you guys can address this in your podcast. Thanks a lot,

680
00:34:23,920 --> 00:34:27,600
Speaker 1: Bye bye. Alright, awesome question. I feel like this is

681
00:34:27,640 --> 00:34:31,359
Speaker 1: getting back to like elementary school philosophy, you know, like

682
00:34:31,440 --> 00:34:33,520
Speaker 1: which came first, the chicken or the egg. It's a

683
00:34:33,520 --> 00:34:35,759
Speaker 1: deep question about the early history of the universe. I

684
00:34:35,800 --> 00:34:39,000
Speaker 1: love this stuff. Yeah, so gals Um kind of acknowledges,

685
00:34:39,040 --> 00:34:42,560
Speaker 1: first of all, that matter and energy are really closely related.

686
00:34:42,880 --> 00:34:45,560
Speaker 1: And I always thought that matter is energy, right, isn't

687
00:34:45,600 --> 00:34:47,719
Speaker 1: that what E mc squares says That they're the same

688
00:34:47,760 --> 00:34:50,600
Speaker 1: thing sort of, But it's not entirely symmetric. The way

689
00:34:50,760 --> 00:34:53,040
Speaker 1: I would explain it is that mass is a form

690
00:34:53,120 --> 00:34:56,440
Speaker 1: of energy. Right. The reason things have mass, it's because

691
00:34:56,440 --> 00:34:59,600
Speaker 1: they have internal stored energy. And so you can think

692
00:34:59,600 --> 00:35:02,120
Speaker 1: about mass is like a form of energy, or you

693
00:35:02,160 --> 00:35:04,400
Speaker 1: can think about mass is like a little dial that

694
00:35:04,480 --> 00:35:07,919
Speaker 1: tells you how much stored energy is inside this thing.

695
00:35:08,080 --> 00:35:10,440
Speaker 1: But you can turn mass into other kinds of energy,

696
00:35:10,520 --> 00:35:13,360
Speaker 1: like velocity, or you can turn velocity into mass and

697
00:35:13,440 --> 00:35:15,640
Speaker 1: so you can think about mass it's like a form

698
00:35:15,760 --> 00:35:18,600
Speaker 1: of energy. But energy is not a form of mass,

699
00:35:18,640 --> 00:35:21,120
Speaker 1: so they're not entirely symmetric. Oh I see, it's not

700
00:35:21,239 --> 00:35:24,439
Speaker 1: really an equivalence. E equals mc square. It just says

701
00:35:24,480 --> 00:35:26,360
Speaker 1: that mass is energy, but it doesn't say that energy

702
00:35:26,440 --> 00:35:29,839
Speaker 1: is mass. Yeah, equals mc squared tells you how much

703
00:35:29,960 --> 00:35:33,400
Speaker 1: energy is stored in an object at rest with mass.

704
00:35:33,640 --> 00:35:37,640
Speaker 1: M I see, So I guess you're saying that matter

705
00:35:38,080 --> 00:35:40,960
Speaker 1: is a subset of energy, and therefore therefore it can

706
00:35:41,040 --> 00:35:43,839
Speaker 1: be first, can it. Yeah, that's right. Matter is a

707
00:35:43,920 --> 00:35:46,719
Speaker 1: kind of energy, so it can't really predate energy. You

708
00:35:46,760 --> 00:35:49,600
Speaker 1: can't imagine a scenario where you have matter in the

709
00:35:49,719 --> 00:35:53,000
Speaker 1: universe without energy because matter is a kind of energy.

710
00:35:53,880 --> 00:35:56,400
Speaker 1: It's like saying an egg is really a baby chicken,

711
00:35:56,520 --> 00:36:00,120
Speaker 1: so therefore the chicken can first. Not a biologist not

712
00:36:00,160 --> 00:36:02,600
Speaker 1: going to weigh in on that one. But it sounded good.

713
00:36:03,280 --> 00:36:06,080
Speaker 1: That sounded good. The mass funded, right, we'll go with that.

714
00:36:07,560 --> 00:36:09,319
Speaker 1: I'll have to do a simulation later, but yeah, it

715
00:36:09,320 --> 00:36:13,440
Speaker 1: sounded another paper. Oh man, we are cracking out the

716
00:36:13,480 --> 00:36:15,880
Speaker 1: assigns here. So I think it's pretty clear that energy

717
00:36:16,320 --> 00:36:19,319
Speaker 1: came first, because you can't have matter without energy. But

718
00:36:19,400 --> 00:36:21,680
Speaker 1: it's interesting to think about sort of what forms of

719
00:36:21,800 --> 00:36:24,600
Speaker 1: energy were created in the universe at what time, When

720
00:36:24,600 --> 00:36:27,120
Speaker 1: did matter come about, When did we get radiation, what

721
00:36:27,239 --> 00:36:29,800
Speaker 1: came first, How did that all happen because the history

722
00:36:29,840 --> 00:36:33,160
Speaker 1: is quite complicated and really nuanced. Oh, interesting because you're

723
00:36:33,160 --> 00:36:35,319
Speaker 1: saying that, you know, in the Big Bang, maybe there

724
00:36:35,440 --> 00:36:39,439
Speaker 1: was sort of an opportunity for matter to be more dominant. Yeah.

725
00:36:39,440 --> 00:36:41,200
Speaker 1: The way we think about it in the very early

726
00:36:41,320 --> 00:36:44,400
Speaker 1: universe is that you have very high energy density. Right,

727
00:36:44,480 --> 00:36:46,719
Speaker 1: the universe used to be much more dense, it used

728
00:36:46,719 --> 00:36:49,719
Speaker 1: to be much more compact, it used to be higher temperature,

729
00:36:49,920 --> 00:36:52,600
Speaker 1: so things were flying around, they were crazy, and there

730
00:36:52,640 --> 00:36:55,319
Speaker 1: were such high energy that all the quantum fields were

731
00:36:55,320 --> 00:36:58,160
Speaker 1: buzzing with so much energy that doesn't even really make

732
00:36:58,239 --> 00:37:00,920
Speaker 1: sense to talk about particle in the way we think

733
00:37:00,960 --> 00:37:02,799
Speaker 1: about it. There was a moment very early on in

734
00:37:02,840 --> 00:37:04,839
Speaker 1: the universe when there's a lot of energy, but there

735
00:37:04,840 --> 00:37:08,000
Speaker 1: weren't even really particles flying around in the universe had

736
00:37:08,000 --> 00:37:10,480
Speaker 1: to like cooled down a little bit before you can

737
00:37:10,480 --> 00:37:13,680
Speaker 1: even start to talk about the quantum fields buzzing in

738
00:37:13,680 --> 00:37:15,400
Speaker 1: the way that we think about it today is like

739
00:37:15,440 --> 00:37:18,960
Speaker 1: these little discrete pockets of energy flying around the universe.

740
00:37:19,200 --> 00:37:21,960
Speaker 1: It was just more like a huge ocean of energy,

741
00:37:22,760 --> 00:37:25,839
Speaker 1: like pure like everything was just pure energy. I guess

742
00:37:25,880 --> 00:37:28,760
Speaker 1: the question now that I have is which came first,

743
00:37:28,880 --> 00:37:31,759
Speaker 1: energy or quantum fields. Yeah, that's a great question, and

744
00:37:31,800 --> 00:37:34,759
Speaker 1: we don't know the answer. We have a description of

745
00:37:34,800 --> 00:37:38,200
Speaker 1: the universe in terms of quantum fields. For certain energies,

746
00:37:38,480 --> 00:37:40,720
Speaker 1: like for the energies that exist today in the universe,

747
00:37:40,719 --> 00:37:42,839
Speaker 1: which are very very cold, we know that we can

748
00:37:42,880 --> 00:37:45,400
Speaker 1: describe the universe in terms of quantum fields, and for

749
00:37:45,560 --> 00:37:48,640
Speaker 1: higher energies like what happens inside the Large Hadron Collider

750
00:37:49,040 --> 00:37:51,600
Speaker 1: and going back to the early moments of the universe,

751
00:37:51,800 --> 00:37:55,040
Speaker 1: we can describe that in terms of quantum fields. Beyond that,

752
00:37:55,160 --> 00:37:58,040
Speaker 1: we don't know, Like we have quantum fields, and we

753
00:37:58,120 --> 00:38:00,400
Speaker 1: suspect that those theories and the disc oricteen to the

754
00:38:00,440 --> 00:38:03,399
Speaker 1: universe in terms of quantum fields probably works at very

755
00:38:03,480 --> 00:38:05,960
Speaker 1: very high temperatures very early on in the universe. But

756
00:38:06,000 --> 00:38:08,440
Speaker 1: the truth is that we just don't know. One of

757
00:38:08,440 --> 00:38:10,400
Speaker 1: the reasons we don't know is that we don't understand

758
00:38:10,400 --> 00:38:13,839
Speaker 1: how gravity works in a quantum sense. So what you're

759
00:38:13,840 --> 00:38:16,200
Speaker 1: really asking about is like can you give a quantum

760
00:38:16,239 --> 00:38:19,880
Speaker 1: field description of the universe when gravity was just as

761
00:38:19,960 --> 00:38:22,880
Speaker 1: important as all these other forces? And we don't know

762
00:38:23,000 --> 00:38:25,120
Speaker 1: because we don't have a theory of quantum gravity. So

763
00:38:25,160 --> 00:38:27,960
Speaker 1: we're really pretty clueless about a sort of a quantum

764
00:38:27,960 --> 00:38:32,240
Speaker 1: picture of the universe when gravity was very important early on. Interesting,

765
00:38:32,280 --> 00:38:34,440
Speaker 1: I guess you're saying, you know that in the beginning

766
00:38:34,480 --> 00:38:38,240
Speaker 1: of the universe, at the Big Bang, things were so crazy,

767
00:38:38,320 --> 00:38:42,880
Speaker 1: so crunched together and so high energy density. Did we

768
00:38:42,920 --> 00:38:45,640
Speaker 1: really don't know what was going on at that moment? Yeah,

769
00:38:45,680 --> 00:38:47,879
Speaker 1: in the same way that we don't know today what's

770
00:38:47,920 --> 00:38:50,560
Speaker 1: going on inside a black hole for the same reasons.

771
00:38:50,960 --> 00:38:53,319
Speaker 1: Like you send a particle inside a black hole, we

772
00:38:53,400 --> 00:38:55,480
Speaker 1: think of it like a little wiggle in a quantum field.

773
00:38:55,719 --> 00:38:58,319
Speaker 1: What happens when it goes inside a black hole? Well,

774
00:38:58,360 --> 00:39:01,200
Speaker 1: now it's under very strong gravitational pressure. Is it's still

775
00:39:01,239 --> 00:39:03,719
Speaker 1: a quantum wiggle? Is it turned into something else a

776
00:39:03,719 --> 00:39:06,719
Speaker 1: new kind of matter? Are there gravitational quantum fields? We

777
00:39:06,800 --> 00:39:08,759
Speaker 1: just don't know. In the same way we don't know

778
00:39:08,840 --> 00:39:11,799
Speaker 1: what was the state of the universe when gravity was

779
00:39:11,840 --> 00:39:14,600
Speaker 1: really strong and very important early on. So it might

780
00:39:14,640 --> 00:39:16,400
Speaker 1: be that we can describe in terms of wiggles and

781
00:39:16,480 --> 00:39:18,680
Speaker 1: quantum fields. But it might be that we can't. But

782
00:39:18,719 --> 00:39:20,760
Speaker 1: we do have a pretty nice picture of what happens,

783
00:39:20,800 --> 00:39:24,319
Speaker 1: like after the universe drops in temperature to a point

784
00:39:24,320 --> 00:39:27,120
Speaker 1: where it turns into particles, and we can then think about,

785
00:39:27,200 --> 00:39:29,320
Speaker 1: like how much of the energy in the universe is

786
00:39:29,360 --> 00:39:31,640
Speaker 1: in terms of these particles or in terms of the

787
00:39:31,680 --> 00:39:34,520
Speaker 1: photons that go between them and that kind of stuff. Oh,

788
00:39:34,640 --> 00:39:37,360
Speaker 1: I see, but I guess before that it starts to

789
00:39:37,400 --> 00:39:39,680
Speaker 1: cool off. Does it even make sense to talk about

790
00:39:39,760 --> 00:39:42,080
Speaker 1: energy as we know it? Like inside of a black hole?

791
00:39:42,120 --> 00:39:44,080
Speaker 1: Does it makes sense to talk about energy? Or can

792
00:39:44,120 --> 00:39:47,520
Speaker 1: you still, you know, define energy in a such a scenario.

793
00:39:47,680 --> 00:39:49,759
Speaker 1: We can define energy, but you're right, we don't know

794
00:39:49,800 --> 00:39:52,760
Speaker 1: if it's the most important quantity. Like people think about energy,

795
00:39:52,800 --> 00:39:56,239
Speaker 1: it's fundamental to the universe and a really insightful way

796
00:39:56,280 --> 00:39:58,560
Speaker 1: to think about the state of the universe. Remember that

797
00:39:58,600 --> 00:40:02,120
Speaker 1: we discovered recently that energy is not even conserved in

798
00:40:02,160 --> 00:40:05,120
Speaker 1: the universe. Right, It turns out it's something we can measure,

799
00:40:05,239 --> 00:40:08,600
Speaker 1: and it seems to be conserved in most of our experiments.

800
00:40:08,880 --> 00:40:11,480
Speaker 1: But we know that in an expanding space, if the

801
00:40:11,560 --> 00:40:15,240
Speaker 1: universe is growing. If space itself is changing, the amount

802
00:40:15,239 --> 00:40:18,480
Speaker 1: of energy in the universe is also changing, so energy

803
00:40:18,600 --> 00:40:20,600
Speaker 1: might not be the right way to think about the

804
00:40:20,680 --> 00:40:23,040
Speaker 1: nature of the universe. We talked a few weeks ago

805
00:40:23,040 --> 00:40:25,400
Speaker 1: about what happened in those first few moments of the universe,

806
00:40:25,520 --> 00:40:27,600
Speaker 1: this inflation theory, and you know, we have some like

807
00:40:27,680 --> 00:40:30,120
Speaker 1: pictures of what that means. Maybe there was this insulaton

808
00:40:30,280 --> 00:40:34,320
Speaker 1: field with these influcton particles which decayed into normal matter.

809
00:40:34,640 --> 00:40:37,200
Speaker 1: So you can possibly think about it in terms of

810
00:40:37,239 --> 00:40:39,799
Speaker 1: like weird new quantum fields. But we just don't know

811
00:40:39,840 --> 00:40:42,200
Speaker 1: if any of those theories are at all accurate. They're

812
00:40:42,239 --> 00:40:44,960
Speaker 1: just more like sketches of ideas that we're using to

813
00:40:45,000 --> 00:40:47,000
Speaker 1: try to think about it in terms of stuff we

814
00:40:47,040 --> 00:40:49,080
Speaker 1: already know. But but there's no guarantee that the kinds

815
00:40:49,080 --> 00:40:51,400
Speaker 1: of ideas we have are the right ideas. Well. I

816
00:40:51,440 --> 00:40:53,319
Speaker 1: feel like you're saying, like we almost don't even know

817
00:40:53,360 --> 00:40:56,680
Speaker 1: if math worked at the beginning of he never you know,

818
00:40:56,760 --> 00:40:59,680
Speaker 1: like maybe one those one was three back then, you know,

819
00:40:59,680 --> 00:41:02,200
Speaker 1: because energy and things were just popping out of nothingness.

820
00:41:02,320 --> 00:41:04,600
Speaker 1: It's definitely a very weird situation, and I'm pretty sure

821
00:41:04,719 --> 00:41:07,080
Speaker 1: there's going to be mind blowing surprises when we figure

822
00:41:07,120 --> 00:41:09,400
Speaker 1: out how that worked and how to even think about

823
00:41:09,400 --> 00:41:11,120
Speaker 1: it and how to talk about it. And that's one

824
00:41:11,160 --> 00:41:14,000
Speaker 1: reason why we do crazy collisions is super high energy,

825
00:41:14,040 --> 00:41:17,400
Speaker 1: because we want to probe the most extreme situations to

826
00:41:17,440 --> 00:41:20,000
Speaker 1: see when do our theories break down? When do we

827
00:41:20,040 --> 00:41:22,720
Speaker 1: need a new kind of structure. You know, quantum field

828
00:41:22,719 --> 00:41:25,680
Speaker 1: theories themselves are only a few decades old, and they

829
00:41:25,719 --> 00:41:28,480
Speaker 1: came into play to explain collisions at high energy that

830
00:41:28,520 --> 00:41:32,560
Speaker 1: we couldn't otherwise understand. And so maybe that a crazier

831
00:41:32,640 --> 00:41:34,760
Speaker 1: high energies we need a whole new kind of idea

832
00:41:34,760 --> 00:41:37,560
Speaker 1: about what's going on in the universe, or maybe quantum

833
00:41:37,560 --> 00:41:39,960
Speaker 1: fields will describe everything up to the playing scale. We

834
00:41:40,040 --> 00:41:43,279
Speaker 1: just don't know. Yeah, I think that's how I would

835
00:41:43,280 --> 00:41:45,879
Speaker 1: describe my childhood as well. It's a lot of weird

836
00:41:45,880 --> 00:41:50,640
Speaker 1: things happen and I'm still trying to understand it. Did

837
00:41:50,680 --> 00:41:55,200
Speaker 1: you break mathematics? I probably thought I could. Yeah, that

838
00:41:55,239 --> 00:41:56,640
Speaker 1: broke a lot of things when I was a kid.

839
00:41:56,960 --> 00:41:58,600
Speaker 1: But I think I think your main point, though, is

840
00:41:58,600 --> 00:42:01,879
Speaker 1: that we maybe don't know what happened during the Big Bang,

841
00:42:01,920 --> 00:42:04,200
Speaker 1: were before the Big Bang, were right after the Big Bang?

842
00:42:04,239 --> 00:42:06,560
Speaker 1: We do have kind of a clear picture of how

843
00:42:06,640 --> 00:42:08,960
Speaker 1: much of the universe was matter and how much of

844
00:42:09,000 --> 00:42:13,000
Speaker 1: it was kind of like flying energy, which you call radiation. Yeah,

845
00:42:13,040 --> 00:42:17,040
Speaker 1: so some mysterious thing happens, the universe exists, and then

846
00:42:17,280 --> 00:42:20,560
Speaker 1: some other mysterious thing happens. The universe inflates and expands

847
00:42:20,600 --> 00:42:22,920
Speaker 1: and cools down rapidly, and just after that we can

848
00:42:22,920 --> 00:42:25,600
Speaker 1: start to talk more concretely about quantum fields. And in

849
00:42:25,640 --> 00:42:27,960
Speaker 1: that situation, when the universe is still very very hot,

850
00:42:28,000 --> 00:42:30,320
Speaker 1: but we can talk about it in terms of quantum fields.

851
00:42:30,800 --> 00:42:33,759
Speaker 1: It's a really interesting situation because every particle back then

852
00:42:34,040 --> 00:42:37,319
Speaker 1: was massless. This is before the Higgs boson even came

853
00:42:37,360 --> 00:42:40,120
Speaker 1: into play, and so every particle, the electron, the w,

854
00:42:40,320 --> 00:42:43,720
Speaker 1: the z, all these particles had zero mass. Whoa, whoa,

855
00:42:43,960 --> 00:42:47,399
Speaker 1: Yeah that's wild. Yeah, at some point the universe had

856
00:42:47,800 --> 00:42:50,759
Speaker 1: nothing had mass because the Higgs field hadn't come into being. Yeah,

857
00:42:50,800 --> 00:42:53,360
Speaker 1: none of these initial particles had mass. You could still

858
00:42:53,600 --> 00:42:57,160
Speaker 1: have mass by combining particles into some like object, the

859
00:42:57,200 --> 00:42:59,360
Speaker 1: same way like if you put a bunch of photons

860
00:42:59,400 --> 00:43:02,839
Speaker 1: into a rage box, it actually gains mass because any

861
00:43:02,840 --> 00:43:06,719
Speaker 1: stored energy turns into mass. But the particles themselves. None

862
00:43:06,719 --> 00:43:09,320
Speaker 1: of them had mass in the very early universe until

863
00:43:09,400 --> 00:43:12,439
Speaker 1: the Higgs boson sort of settled into this weird state

864
00:43:12,480 --> 00:43:15,440
Speaker 1: that it's in today that gives them that mass. So

865
00:43:15,480 --> 00:43:18,600
Speaker 1: if it's nothing had mass, that means nothing what not,

866
00:43:18,800 --> 00:43:21,000
Speaker 1: Nothing mattered kind of in a way like you didn't

867
00:43:21,000 --> 00:43:24,200
Speaker 1: have matter. Particle physicists talk about the difference between matter

868
00:43:24,400 --> 00:43:27,360
Speaker 1: and radiation, and it's sort of a fuzzy line because

869
00:43:27,640 --> 00:43:30,759
Speaker 1: you know, when we talk about radiation chemically, we say, like, oh,

870
00:43:30,800 --> 00:43:34,560
Speaker 1: electrons are alpha particles, that's radiation, even though they have mass.

871
00:43:34,600 --> 00:43:37,480
Speaker 1: So we have all sorts of totally inconsistent definitions of radiation.

872
00:43:37,840 --> 00:43:40,480
Speaker 1: But in terms of like early universe physics, we divide

873
00:43:40,480 --> 00:43:43,480
Speaker 1: things into matter and radiation. Things that are radiation or

874
00:43:43,520 --> 00:43:46,120
Speaker 1: things that are traveling at light speed, and things that

875
00:43:46,200 --> 00:43:48,560
Speaker 1: are matter things that are traveling not at light speed.

876
00:43:48,960 --> 00:43:52,080
Speaker 1: But in the very early universe everything was massless, so

877
00:43:52,160 --> 00:43:54,040
Speaker 1: everything was moving at light speed, so it was just

878
00:43:54,080 --> 00:43:57,839
Speaker 1: a d radiation. Oh interesting, So we don't know which

879
00:43:57,920 --> 00:44:01,240
Speaker 1: can first, matter or energy, but we know which game second,

880
00:44:02,560 --> 00:44:05,600
Speaker 1: which is a radiation which is really energy, right yea.

881
00:44:05,840 --> 00:44:07,759
Speaker 1: So in the first moments of the universe that we

882
00:44:07,800 --> 00:44:10,440
Speaker 1: can really talk about we have all these buzzing quantum

883
00:44:10,440 --> 00:44:14,480
Speaker 1: fields with massless particles flying everywhere. The whole universe was radiation.

884
00:44:14,640 --> 00:44:18,080
Speaker 1: Then the Higgs field broke that symmetry between electromagnetism and

885
00:44:18,120 --> 00:44:20,920
Speaker 1: the weak force, made the W and the Z massive

886
00:44:21,239 --> 00:44:23,920
Speaker 1: and also made a bunch of other particles massive, and

887
00:44:23,960 --> 00:44:26,600
Speaker 1: then you have matter, and then the electron has mass.

888
00:44:26,840 --> 00:44:29,600
Speaker 1: You know, the corks have mass, and so that happened

889
00:44:29,680 --> 00:44:32,560
Speaker 1: very early on in the universe. But still most of

890
00:44:32,600 --> 00:44:35,239
Speaker 1: the energy in the universe was in terms of radiation

891
00:44:35,640 --> 00:44:39,960
Speaker 1: photons and other massless particles, meaning like it was in particles,

892
00:44:39,960 --> 00:44:42,000
Speaker 1: but it wasn't. It was in particles moving at the

893
00:44:42,040 --> 00:44:44,440
Speaker 1: speed of light. And so the first like fifty thousand

894
00:44:44,520 --> 00:44:48,600
Speaker 1: years of the universe was a radiation dominated era. Most

895
00:44:48,640 --> 00:44:51,080
Speaker 1: of the energy in the universe was in terms of

896
00:44:51,480 --> 00:44:55,000
Speaker 1: massless speed of light particles for the first fifty thousand years,

897
00:44:55,280 --> 00:44:59,160
Speaker 1: which sounds like a lot in human years, but in

898
00:44:59,239 --> 00:45:01,680
Speaker 1: the terms of the age of the universe, it's like

899
00:45:01,719 --> 00:45:04,319
Speaker 1: it's like just the first blink. Yeah, exactly, it's just

900
00:45:04,360 --> 00:45:06,959
Speaker 1: like a blip. Like if you ruled for fifty years,

901
00:45:07,000 --> 00:45:09,840
Speaker 1: that sounds pretty impressive, But if the universe is fourteen

902
00:45:09,880 --> 00:45:13,440
Speaker 1: billion years, then it's almost forgettable, all right. So then

903
00:45:13,520 --> 00:45:16,400
Speaker 1: at first it was all radiation and then what happened?

904
00:45:16,480 --> 00:45:18,600
Speaker 1: When did it change? Things are expanding and things are

905
00:45:18,600 --> 00:45:22,400
Speaker 1: cooling down, and that expansion affects matter and radiation differently

906
00:45:22,719 --> 00:45:25,920
Speaker 1: because as the universe expands, matter gets dilute. Right, the

907
00:45:25,960 --> 00:45:28,640
Speaker 1: same amount of matter exists, we have more volume, so

908
00:45:28,719 --> 00:45:32,520
Speaker 1: the density of matter drops. That makes sense, But radiation

909
00:45:32,640 --> 00:45:36,760
Speaker 1: is effected in another way. As space expands, radiation gets dilute.

910
00:45:36,840 --> 00:45:39,480
Speaker 1: It also gets red shifted. Like if you have a

911
00:45:39,520 --> 00:45:42,920
Speaker 1: photon in space and that space expands, it doesn't just

912
00:45:42,960 --> 00:45:45,760
Speaker 1: make the photon have fewer neighbors, It makes the photon

913
00:45:45,840 --> 00:45:49,200
Speaker 1: have a longer wavelength, which means less energy. So this

914
00:45:49,360 --> 00:45:53,720
Speaker 1: red shifting of radiation means that radiation loses energy faster

915
00:45:54,320 --> 00:45:58,799
Speaker 1: than matter does as the universe expands. Whoa interesting, It's

916
00:45:58,800 --> 00:46:01,560
Speaker 1: like it slows down light. But you can't slow down light,

917
00:46:01,600 --> 00:46:04,759
Speaker 1: but it just it makes it kind of less energetic. Yeah,

918
00:46:04,760 --> 00:46:08,360
Speaker 1: it steals away energy from light and we know that happens.

919
00:46:08,520 --> 00:46:10,960
Speaker 1: We see it all the time. Like the cosmic background

920
00:46:11,040 --> 00:46:15,160
Speaker 1: radiation was generated actually really high energies like three thousand

921
00:46:15,200 --> 00:46:18,320
Speaker 1: degrees kelvin. We see it now like three degrees kelvin

922
00:46:18,360 --> 00:46:21,359
Speaker 1: really long wavelengths because the universe has expanded and red

923
00:46:21,400 --> 00:46:24,000
Speaker 1: shifted all of that, and so radiation sort of lost

924
00:46:24,040 --> 00:46:26,719
Speaker 1: out after about fifty thousand years, and then for a

925
00:46:26,800 --> 00:46:29,719
Speaker 1: long time the universe was matter dominated. Most of the

926
00:46:29,800 --> 00:46:32,000
Speaker 1: energy in the universe was in the form of matter,

927
00:46:33,400 --> 00:46:36,600
Speaker 1: and a lot of that came because matter kind of

928
00:46:36,840 --> 00:46:40,839
Speaker 1: transformed from that early energy, right, like things, things kind

929
00:46:40,880 --> 00:46:43,719
Speaker 1: of clumped together and then they became matter. Yeah, the

930
00:46:43,800 --> 00:46:46,400
Speaker 1: Higgs boson gave math to a lot of those particles

931
00:46:46,440 --> 00:46:49,360
Speaker 1: and shifted them from the radiation category into the matter

932
00:46:49,440 --> 00:46:52,600
Speaker 1: category because now they had mass. And so then there

933
00:46:52,640 --> 00:46:56,279
Speaker 1: was this huge universe filled with particles, you know, electrons

934
00:46:56,320 --> 00:46:59,840
Speaker 1: and protons, and stars were formed and galaxies were formed,

935
00:46:59,840 --> 00:47:01,880
Speaker 1: and I was most of the energy budget of the

936
00:47:01,960 --> 00:47:05,200
Speaker 1: universe for billions of years was in terms of stuff,

937
00:47:05,239 --> 00:47:07,959
Speaker 1: mostly dark matter actually, but in terms of like things

938
00:47:07,960 --> 00:47:09,960
Speaker 1: we would think of today as stuff. It was the

939
00:47:10,000 --> 00:47:13,480
Speaker 1: stuff dominated era of the universe. WHOA, well, you just

940
00:47:13,480 --> 00:47:16,200
Speaker 1: blew my mind a little bit here, uh, either in

941
00:47:16,239 --> 00:47:18,640
Speaker 1: the dark matter here as a surprise twist here, so

942
00:47:19,160 --> 00:47:20,960
Speaker 1: like we know where dark matter came from, is that

943
00:47:21,000 --> 00:47:23,360
Speaker 1: what you're saying, Like, we traced the history of dark matter,

944
00:47:23,480 --> 00:47:25,279
Speaker 1: we know that dark matter was made at the same

945
00:47:25,320 --> 00:47:27,960
Speaker 1: time as all those other particles. When the energy in

946
00:47:27,960 --> 00:47:31,600
Speaker 1: the early universe coalesced into the different fields, electrons, and quirks.

947
00:47:31,880 --> 00:47:35,040
Speaker 1: That happened equally across all of the fields. And so

948
00:47:35,160 --> 00:47:38,120
Speaker 1: if dark matter is a particle and it's described by

949
00:47:38,120 --> 00:47:40,560
Speaker 1: a quantum field, then it was also made in the

950
00:47:40,640 --> 00:47:43,440
Speaker 1: early universe and it's been around since then. We're pretty

951
00:47:43,440 --> 00:47:46,280
Speaker 1: sure about that because it's changed the way the universe

952
00:47:46,280 --> 00:47:49,440
Speaker 1: has evolved. Like the reason we have stars and galaxies

953
00:47:49,760 --> 00:47:52,200
Speaker 1: is because of the gravity of dark matter early on

954
00:47:52,360 --> 00:47:54,520
Speaker 1: in the universe. So it had to have been around

955
00:47:54,680 --> 00:47:56,960
Speaker 1: for a long time. So when you say that the

956
00:47:57,040 --> 00:48:00,680
Speaker 1: universe became matter dominated, really you mean dark matter are dominated,

957
00:48:00,680 --> 00:48:04,080
Speaker 1: because there's like, even since the beginning of time and

958
00:48:04,520 --> 00:48:07,640
Speaker 1: or those early moments, there's been you know, five times

959
00:48:07,640 --> 00:48:10,320
Speaker 1: more dark matter than regular matter. Yeah, although the ratio

960
00:48:10,440 --> 00:48:13,239
Speaker 1: between dark matter and regular matter does change through the

961
00:48:13,280 --> 00:48:15,239
Speaker 1: history of the universe, we think there was even more

962
00:48:15,320 --> 00:48:17,920
Speaker 1: dark matter early on and some of it converted into

963
00:48:17,960 --> 00:48:20,560
Speaker 1: normal matter. That's a whole other podcast episode. We talked

964
00:48:20,560 --> 00:48:23,279
Speaker 1: about the whimp miracle ones about how we think dark

965
00:48:23,320 --> 00:48:26,399
Speaker 1: matter converted into normal matter. But yes, there's been dark

966
00:48:26,440 --> 00:48:29,800
Speaker 1: matter since the very beginning. Well, and so when really

967
00:48:30,560 --> 00:48:33,640
Speaker 1: in this period of matter domination, really you're saying it's

968
00:48:33,719 --> 00:48:37,240
Speaker 1: dark matter domination. Dark matter ruled for about nine billion

969
00:48:37,360 --> 00:48:41,400
Speaker 1: years long lived dark matter, but then something happened, the

970
00:48:41,560 --> 00:48:45,440
Speaker 1: dark energy revolution. Yes, dark energy took over. I remember

971
00:48:45,440 --> 00:48:48,320
Speaker 1: that the universe is expanding, and so as the universe

972
00:48:48,400 --> 00:48:51,719
Speaker 1: gets bigger and bigger, every new chunk of space that's

973
00:48:51,760 --> 00:48:55,760
Speaker 1: created comes with its own dark energy. So, unlike matter

974
00:48:55,880 --> 00:48:59,480
Speaker 1: and radiation, which get more and more dilute as space expands,

975
00:48:59,680 --> 00:49:02,360
Speaker 1: dark energy doesn't get diluted because a new chunk of

976
00:49:02,400 --> 00:49:05,440
Speaker 1: space comes with its own fresh dark matter. So as

977
00:49:05,520 --> 00:49:09,680
Speaker 1: the universe expands, dark energy starts to climb, and eventually,

978
00:49:09,719 --> 00:49:12,399
Speaker 1: at some point it crosses over and there's more dark

979
00:49:12,560 --> 00:49:14,920
Speaker 1: energy in the universe than there is energy in the

980
00:49:15,000 --> 00:49:17,520
Speaker 1: dark matter. And that happened about four or five billion

981
00:49:17,640 --> 00:49:20,560
Speaker 1: years ago. I see, yeah, And we're still in that period, right,

982
00:49:20,640 --> 00:49:23,239
Speaker 1: We're still in the dark energy dynasty. We're still in

983
00:49:23,280 --> 00:49:25,120
Speaker 1: that period, and this period is gonna last for a

984
00:49:25,160 --> 00:49:28,840
Speaker 1: long long time. Maybe forever, because once dark energy is dominant,

985
00:49:28,880 --> 00:49:31,680
Speaker 1: it accelerates the expansion of the universe, which makes more

986
00:49:31,760 --> 00:49:34,759
Speaker 1: dark energy more rapidly. And so now dark energy is

987
00:49:34,800 --> 00:49:38,600
Speaker 1: like completely dominant sev of the energy of the universe,

988
00:49:38,640 --> 00:49:41,000
Speaker 1: and the future suggests it's going to get higher and higher,

989
00:49:41,040 --> 00:49:44,200
Speaker 1: and it might even expand the universe to almost nothingness

990
00:49:44,280 --> 00:49:48,359
Speaker 1: right into my dad expanded into that there's nothing left. Yeah.

991
00:49:48,400 --> 00:49:51,239
Speaker 1: Although remember, dark energy is something we observe, we see

992
00:49:51,280 --> 00:49:53,680
Speaker 1: it happening. We have these ideas about how it works,

993
00:49:53,680 --> 00:49:55,839
Speaker 1: but we're really not very confident in it, which makes

994
00:49:55,840 --> 00:49:58,520
Speaker 1: it very difficult to make solid predictions for the future

995
00:49:58,560 --> 00:50:00,919
Speaker 1: of dark energy. You could turn out the dark energy

996
00:50:01,000 --> 00:50:03,440
Speaker 1: is much more complicated than we imagine. It has some

997
00:50:03,600 --> 00:50:06,160
Speaker 1: weird oscillations in it, for example, and maybe it's going

998
00:50:06,239 --> 00:50:08,319
Speaker 1: to turn around and cause a big crunch. We really

999
00:50:08,360 --> 00:50:10,480
Speaker 1: just can't say for sure because we don't understand it

1000
00:50:10,560 --> 00:50:12,719
Speaker 1: like at all. But I guess we go back to

1001
00:50:13,320 --> 00:50:15,799
Speaker 1: Jews question. He kind of just wanted to know which

1002
00:50:15,840 --> 00:50:17,960
Speaker 1: came first, matter or energy. I think what you're saying

1003
00:50:18,000 --> 00:50:19,719
Speaker 1: is that the picture is kind of complicated. It's not

1004
00:50:19,800 --> 00:50:22,000
Speaker 1: just kind of about the sequence of things it's you know,

1005
00:50:22,000 --> 00:50:24,680
Speaker 1: two physicists. It's kind of like which is more dominant,

1006
00:50:25,040 --> 00:50:28,640
Speaker 1: and that that question has changed over the Big Bang

1007
00:50:28,680 --> 00:50:31,600
Speaker 1: and the history of the universe. It's a really fascinating

1008
00:50:31,640 --> 00:50:34,640
Speaker 1: history and nuanced and one that we've only really picked

1009
00:50:34,680 --> 00:50:37,279
Speaker 1: apart in the last couple of decades. So we're just

1010
00:50:37,360 --> 00:50:40,000
Speaker 1: at the very beginning of understanding the whole history of

1011
00:50:40,000 --> 00:50:42,840
Speaker 1: the universe in terms of its energy budget, how it formed,

1012
00:50:42,880 --> 00:50:45,120
Speaker 1: and how that evolved. N see. But I guess to

1013
00:50:45,160 --> 00:50:47,880
Speaker 1: answer the question the question, the answer is that energy

1014
00:50:47,920 --> 00:50:50,200
Speaker 1: came first, that's kind of for sure you sort of

1015
00:50:50,280 --> 00:50:53,040
Speaker 1: have high confidence in. But in terms of what came second,

1016
00:50:53,040 --> 00:50:55,840
Speaker 1: and third and four, that's been changing and it's a

1017
00:50:55,880 --> 00:50:59,200
Speaker 1: more complex picture. And can we described the early moments

1018
00:50:59,200 --> 00:51:02,200
Speaker 1: of the universe in turn energy? That is an open question. Yeah,

1019
00:51:02,280 --> 00:51:05,960
Speaker 1: math otherians, I think people who ate math. That's a

1020
00:51:06,040 --> 00:51:08,000
Speaker 1: question for people to chew on. I'm sure we'll have

1021
00:51:08,040 --> 00:51:10,440
Speaker 1: a very filling answer. All right. Well, thank you Jeels

1022
00:51:10,520 --> 00:51:13,239
Speaker 1: for that great question, and thank you to everyone who

1023
00:51:13,280 --> 00:51:16,000
Speaker 1: sent in their questions. We really enjoy answering them on

1024
00:51:16,040 --> 00:51:19,319
Speaker 1: the podcast. We absolutely do. We love your messages with

1025
00:51:19,520 --> 00:51:22,200
Speaker 1: or with out questions, so please don't be shy if

1026
00:51:22,200 --> 00:51:24,839
Speaker 1: it's something you've been thinking about, don't hesitate right to us.

1027
00:51:24,880 --> 00:51:27,759
Speaker 1: Do questions at Daniel and Jorne dot com. Yeah, we

1028
00:51:27,800 --> 00:51:31,319
Speaker 1: look forward to your awesome questions. Until then, keep being

1029
00:51:31,320 --> 00:51:34,080
Speaker 1: curious about the universe. Come up with questions and look

1030
00:51:34,080 --> 00:51:36,400
Speaker 1: at the things you're on you and think about what

1031
00:51:36,600 --> 00:51:38,600
Speaker 1: might have come first for a second or third, or

1032
00:51:38,960 --> 00:51:41,319
Speaker 1: whether or not you can get a PhD. Of a

1033
00:51:41,360 --> 00:51:46,279
Speaker 1: PhD because science is just people asking questions and that

1034
00:51:46,320 --> 00:51:49,040
Speaker 1: includes you. We hope you enjoyed that. Thanks for joining us,

1035
00:51:49,680 --> 00:51:59,759
Speaker 1: See you next time. Thanks for listening, and remember that

1036
00:52:00,000 --> 00:52:02,680
Speaker 1: Anniel and Jorge Explain the Universe is a production of

1037
00:52:02,760 --> 00:52:06,120
Speaker 1: I Heart Radio. Or more podcast from my Heart Radio

1038
00:52:06,280 --> 00:52:09,840
Speaker 1: visit the I heart Radio app, Apple Podcasts, or wherever

1039
00:52:09,960 --> 00:52:17,240
Speaker 1: you listen to your favorite shows. Ye