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Speaker 1: Hey, Daniel, So we're answering more listener questions today.

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Speaker 2: Oh, yes, we are.

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Speaker 1: What number is it today?

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Speaker 2: You know, I sort of gave up on giving them

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Speaker 2: numbers in order why. I figured, you know, we just

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Speaker 2: go on vibes rather than being limited by the traditional

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Speaker 2: numbering system.

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Speaker 1: So we're just doing random numbers now? Or are their

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Speaker 1: secret codes embedded in the numbers.

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Speaker 2: I'm not just going to give that answer away right now.

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Speaker 1: I see. So you were just picking numbers out of the.

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Speaker 2: Air, just the same way we answer questions, picking answers

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Speaker 2: out of the air, and sometimes it aligns with reality.

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Speaker 1: You're just a physicist of typing on a typewriter, one

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Speaker 1: of many, and then statistically, eventually one of you will

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Speaker 1: type out the answers to the universe. Maybe you'll be

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Speaker 1: the number of this episode. Hi am Joege, a cartoonist

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Speaker 1: and the author of Oliver's Great Big Universe.

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Speaker 2: Hi. I'm Daniel. I'm a particle physicist, professor at UC Irvine,

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Speaker 2: and I hope to one day type in the true

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Speaker 2: explanation for the universe.

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Speaker 1: Like you come up with it yourself or are you're

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Speaker 1: just taking notes?

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Speaker 2: Well, you know, Mozart said he was basically taking dictation

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Speaker 2: from God. So maybe I can just be a vessel

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Speaker 2: for the truth.

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Speaker 1: I say, you're born again? Is that what's going on?

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Speaker 2: If I could one day be the Mozart of physics,

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Speaker 2: I feel like that would be pretty good.

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Speaker 1: Maybe they'll call Mozart the White Sun of music.

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Speaker 2: Oh man, that's so ridiculous. I can't laugh about it.

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Speaker 1: I just blew your mind. But you got a dream big.

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Speaker 2: That's like at my university, Rice, they got tired of

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Speaker 2: people calling them the Harvard of the South, so they

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Speaker 2: printed up a bunch of shirts saying Harvard is the

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Speaker 2: Rice of the.

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Speaker 1: North aspirational t shirts.

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Speaker 2: Yeah. Yeah, it's a clever joke, but not really, folks.

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Speaker 1: So if you're the most sort of physics, would that

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Speaker 1: make me the Soliary of physics? Or am I the

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Speaker 1: Mozart of podcast hosting?

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Speaker 2: No, man, you're the Beethoven of cartooning.

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Speaker 1: There you go.

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Speaker 2: I think maybe we should get Bach to physics though, hmm.

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Speaker 1: Or maybe there's a bag of basket weaving already. But anyways,

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Speaker 1: welcome to our podcast, Daniel and Jorge Explain the Universe,

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Speaker 1: a production of iHeartRadio.

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Speaker 2: In which we do our best to compose a symphony

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Speaker 2: of understanding to bring into harmony your brain with the universe.

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Speaker 2: We think that everything that's out there is somehow following

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Speaker 2: physical laws, laws that are rational, that are mathematical. That

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Speaker 2: makes sense to our tiny little human brains. Our goal

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Speaker 2: is to bring you up to speed with a current

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Speaker 2: effort to write down the opera of the universe and

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Speaker 2: perform it for you.

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Speaker 1: That's right. We try to belt out the melody of

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Speaker 1: the loss of physics and also singing the praises of

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Speaker 1: the amazing scientists that are out there trying to discover

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Speaker 1: what is the song of the universe and in what

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Speaker 1: key is it in?

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Speaker 2: Do you think when we have the final melodic understanding

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Speaker 2: of the universe we'll find it beautiful and harmonious? What

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Speaker 2: if it's like Philip Glass, just like a bunch of

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Speaker 2: random notes.

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Speaker 1: You mean, like, are we gonna like the music of

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Speaker 1: the universe? Yeah? Or is it not going to be

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Speaker 1: of our taste?

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Speaker 2: Yeah? Exactly. For the same reason, I wonder why we

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Speaker 2: often find the earth beautiful in random landscapes. We're like,

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Speaker 2: oh wow, look how pretty? Why do we find it pretty?

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Speaker 2: Does that mean we're likely to find the explanations for

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Speaker 2: the universe also to be pretty or beautiful or just

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Speaker 2: sort of subjectively appealing.

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Speaker 1: M you mean to give us thumbs down? If you

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Speaker 1: didn't like it, you're like, oh, that's the universe. Swipe left,

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Speaker 1: no thanks.

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Speaker 3: Yeah.

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Speaker 2: I wonder if there are aliens out there that have

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Speaker 2: evolved on their planet and they're like, man, this place

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Speaker 2: is kind of a dump, and they would also think

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Speaker 2: the universe is just kind of blah, whereas it's sort

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Speaker 2: of human to find our surroundings beautiful, or maybe it's not.

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Speaker 2: Maybe that's universal.

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Speaker 1: Who knows, Well, don't I say that beauty and our

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Speaker 1: appreciation of what we find beautiful is maybe genetic, Like

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Speaker 1: we've evolved to like certain colors and certain landscapes just

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Speaker 1: because maybe it helps us survive. Maybe only the physicists

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Speaker 1: who find the universe beautiful are the ones who are

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Speaker 1: going to survive.

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Speaker 2: How does it help us survive to like trees and

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Speaker 2: hills and waterfalls and that kind of stuff?

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Speaker 1: Well, all of those things are signs of life, right,

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Speaker 1: Like it's helpful to like water and green, right, So.

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Speaker 2: What does it say about me that I like desert scenes?

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Speaker 1: It means maybe you were born in Israel.

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Speaker 2: Or have very dry tastes.

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Speaker 1: All of your ancestors they didn't like deserts. Probably, uh,

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Speaker 1: they didn't quite make it me.

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Speaker 2: Yeah, but none of my ancestors were born in the desert,

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Speaker 2: so that doesn't really work anyway. It's not a time

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Speaker 2: to dig into Daniel's evolutionary history.

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Speaker 1: Yeah, the whites and line is not our topic here today.

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Speaker 1: Our topic here today is questions. Questions that scientists ask

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Speaker 1: about the universe, that they ask about how things work,

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Speaker 1: and that trickle down to what everyday people are asking

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Speaker 1: about their everyday lives.

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Speaker 2: That's right. We are all curious about the music of

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Speaker 2: the universe. Is it possible to make sense of it?

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Speaker 2: Can we boil down everything that's out there into ideas

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Speaker 2: that fit into our heads? And we encourage you to

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Speaker 2: also ask questions about the nature of the universe. And

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Speaker 2: we want to hear your questions. We want to hear

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Speaker 2: from you when things don't make sense, when you need

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Speaker 2: a little bit of help sticking ideas together and explaining

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Speaker 2: everything that you see out there in the universe.

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Speaker 1: That's right. Sometimes people send us questions and sometimes we

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Speaker 1: answer them here on the podcast, and so to the

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Speaker 1: on the program, we'll be tackling listener questions. Now, Daniel,

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Speaker 1: you gave this one an odd number. What was the number?

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Speaker 2: You gave it six hundred and seventy two, four hundred

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Speaker 2: and ninety one.

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Speaker 1: And that number was that random? Or is this your

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Speaker 1: go to random number?

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Speaker 2: That's not my go to random number. Last time you

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Speaker 2: were making fun of me for keeping track of these

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Speaker 2: episodes since they'd gotten to such a large number. So

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Speaker 2: I decided, let's just go with vibes. And I felt like,

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Speaker 2: what number does this episode want to be? And that's

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Speaker 2: the number I typed out.

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Speaker 1: Interesting, so this episode talked to you even though we

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Speaker 1: haven't recorded it yet.

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Speaker 2: That's right, We had met yet recorded. But of course

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Speaker 2: I thought about it in advance, and I thought, what

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Speaker 2: number does this map to? If I had to pick

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Speaker 2: a number for this episode, what would it be? And

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Speaker 2: that's what came out. I see.

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Speaker 1: So it basically it means nothing.

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Speaker 2: It's a one dimensional representation of the high dimensional complexity

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Speaker 2: of the ideas in this episode.

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Speaker 1: So yeah, nothing, that's right, because we have no big

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Speaker 1: ideas here on the program, only tiny ideas.

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Speaker 2: Our big idea is to stimulate crazy questions and ideas

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Speaker 2: in your mind out there. So thanks very much to

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Speaker 2: everybody who sends in your questions. Still be shy, write

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Speaker 2: to us two questions at danieland Jorge dot com. We

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Speaker 2: will answer everybody's questions and we might even pick yours

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Speaker 2: to talk about here on the podcast.

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Speaker 1: Yeah, like we're doing here today. And so today we

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Speaker 1: have three great questions from listeners. We have a question

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Speaker 1: about micro's solar systems, but whether the universe really is

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Speaker 1: all Greek to physicists, and also a question about whether

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Speaker 1: a black hole could destroy our planet, so to cheerful.

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Speaker 2: Topics cosmic importance, I.

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Speaker 1: Am getting six hundred seventy two four one hundred and

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Speaker 1: ninety one vive here.

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Speaker 2: Yeah, right, just feeling it, aren't you? You're feeling it?

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Speaker 1: No, I was being totally totally fake there. So let's

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Speaker 1: jump into our first question, and it comes from Tim.

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Speaker 3: Hey, Daniel, curious if there is such a thing as

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Speaker 3: a small solar system out there somewhere, maybe a place

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Speaker 3: where the planets are the size of marbles or something.

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Speaker 3: I don't think so. I would imagine for this to happen,

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Speaker 3: the star would have to form, which would require a

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Speaker 3: lot of material. But I was just wondering if physics

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Speaker 3: supported us.

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Speaker 2: Thanks all right.

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Speaker 1: I think it's kind of ironic that Tim is asking

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Speaker 1: about tiny solar systems. You know, tiny Tim.

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Speaker 2: Maybe tiny Tim is an ironic nickname, and Tim is

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Speaker 2: like a very large dude.

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Speaker 1: A huge dude like you to John from Robin Hood.

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Speaker 2: Exactly. But I love that Tim's question is about scales

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Speaker 2: because I often wonder about that in the universe, like

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Speaker 2: why do things form in the universe at certain sizes

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Speaker 2: and not other sizes? What does that reveal about the

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Speaker 2: fundamental workings of the universe. Can you have solar systems

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Speaker 2: that are super duper tiny and super duper huge, or

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Speaker 2: is there a reason why galaxies tend to be a

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Speaker 2: certain size and stars tend to be a certain size

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Speaker 2: and planets a certain size? What does that teach us

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Speaker 2: about the fundamental rules of the universe and how they

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Speaker 2: come into balance.

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Speaker 1: Yeah, pretty interesting question about scales out there. And I

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Speaker 1: think we've tackled like the what's the largest planet? But

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Speaker 1: this question is interesting because it talks about, you know,

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Speaker 1: what is the smallest solar system you could have?

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Speaker 2: Yeah, And there's a couple of different angles here, like

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Speaker 2: can you have a miniature sun, What is the smallest

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Speaker 2: possible star you could form? And also how small can

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Speaker 2: you make a planet? So I think both of these

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Speaker 2: are really interesting questions.

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Speaker 1: Yeah, pretty cool, So maybe let's tackle them one at

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Speaker 1: a time. I mean, to a solar system, you need

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Speaker 1: a soul as a sun. So what's the smallest sun

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Speaker 1: that you could make or have?

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Speaker 2: So if you want your solar system to have a

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Speaker 2: sun in the middle of it, and by sun you

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Speaker 2: mean something that's giving off energy, that's fusing, that's creating

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Speaker 2: light and heavier elements at its core, then there is

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Speaker 2: a minimum size there because you need enough stuff for

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Speaker 2: gravity to have enough power to compress the core of

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Speaker 2: this object to be high pressure and high temperature and

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Speaker 2: for fusion to start. There's a reason, for example, why

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Speaker 2: the Sun is glowing and Jupiter is not. Even though

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Speaker 2: Jupiter is an enormous ball of hydrogen and other stuff

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Speaker 2: which could fuse, there isn't enough gravity in Jupiter to

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Speaker 2: kick star fusion at its core. There's not enough pressure

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Speaker 2: in temperature to get that going. So there is a

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Speaker 2: threshold there. There is a minimum size you can have

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Speaker 2: for a star to begin fusion to begin.

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Speaker 1: But could there be one that has already started, or

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Speaker 1: what if you kickstart one, would it just blow everything away?

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Speaker 2: Yeah, that's a cool question. Essentially, you're asking could you

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Speaker 2: ignite a star by injecting fusion into it and then

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Speaker 2: let it go the way you can? For example, have

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Speaker 2: a piece of wood sitting in front of you. It's

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Speaker 2: not burning, but if you heat it up, then it

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Speaker 2: will actually ignite and the rest of the fuel will burn.

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Speaker 2: That I don't think will happen with fusion, because fusion

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Speaker 2: needs a certain temperature and a certain pressure in order

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Speaker 2: to be sustained, Like, it'll just fizzle out if you

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Speaker 2: don't maintain those conditions.

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Speaker 1: You need a certain amount of density too, right.

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Speaker 2: Yeah, yeah, because fusion is hard to accomplish. You know,

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Speaker 2: protons don't like to stick together with other protons. They're

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Speaker 2: both positively charged. They push against each other pretty hard,

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Speaker 2: and so you got to really squeeze them together. You

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Speaker 2: got to make sure it's enough density that have nowhere

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Speaker 2: else to go in order for some fusion to happen.

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Speaker 2: And even if you do that, mostly the protons are

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Speaker 2: not fusing. That's why stars can burn for so long,

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Speaker 2: because there's comparatively little fusion happening. Most of the protons

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Speaker 2: in the center of the Sun are not fusing with

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Speaker 2: other protons. It's a tiny fraction where that's actually accomplished.

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Speaker 2: And that only happens when you have an object like

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Speaker 2: eighty times the mass of Jupiter. So you take Jupiter

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Speaker 2: and you add like seventy nine more jupiters, then you'd

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Speaker 2: have enough mass to create the conditions at the core

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Speaker 2: to make a star.

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Speaker 1: Like it will start burning on its own, for sure,

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Speaker 1: or do you still need something to kind of trigger it.

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Speaker 2: It'll start burning on its own. And that's how all

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Speaker 2: stars have started. You know, enough mass has coalesced together

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Speaker 2: to create the conditions, and then fusion is inevitable because

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Speaker 2: there's enough protons banging against other protons and they fuse

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Speaker 2: and they create energy and that sustains itself.

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Speaker 1: Don't you need sometimes like a supernova to go off

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Speaker 1: somewhere for you to start burning a star.

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Speaker 2: You don't need a supernova for the star to start burning.

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Speaker 2: You do need something to trigger the gravitation or runaway

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Speaker 2: effect to form the star. Like you might have a

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Speaker 2: huge cloud of gas and dust, you know, just like

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Speaker 2: a big molecular cloud. What makes it actually collapse into

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Speaker 2: a star is a little bit of a question. You

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Speaker 2: might just have like a seed of a slightly heavier

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Speaker 2: element from something else, or you could have a shockwave

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Speaker 2: from a supernova that just like triggers the collapse. That

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Speaker 2: collapse still takes millions and millions of years. And then

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Speaker 2: once the star forms, fusion starts at the core.

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Speaker 1: Could a supernova trigger a tiny star to start burning

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Speaker 1: or not? Or as you said, it just wouldn't sustain itself.

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Speaker 2: Yeah, it just wouldn't sustain itself because it's not hot

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Speaker 2: enough and there's not enough pressure. So even if you

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Speaker 2: like created your own fusion at the heart of a star,

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Speaker 2: that heat would then just dissipate and wouldn't ignite more fusion.

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Speaker 2: You need that temperature and that pressure, like we do

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Speaker 2: that here on Earth and magnetize fusion and we can

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Speaker 2: get a few fusion reactions to go. But unless you

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Speaker 2: have enough temperature and pressure and density, it doesn't ignice

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Speaker 2: so that it's self sustaining.

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Speaker 1: So then what's the smallest star we could get or

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Speaker 1: have in nature?

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Speaker 2: So in order to have our kind of fusion, like

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Speaker 2: the kind of fusion in our star, you need eighty

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Speaker 2: times the mass of.

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Speaker 1: Jupiter eighty times the mass. But then how big would

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Speaker 1: that sun be? It wouldn't be eighty times bigger than

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Speaker 1: Jupiter necessarily, it might be more compact.

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Speaker 2: Oh that's right, it wouldn't be eighty times the volume

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Speaker 2: of Jupiter because it'd be much more dense. But we

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Speaker 2: have lots of small stars in the galaxy. Of fact,

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Speaker 2: our star is quite heavy and quite big compared to

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Speaker 2: the average star, which is a red dwarf. So red

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Speaker 2: dwarfs go down to like ten percent of the mass

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Speaker 2: of the Sun.

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Speaker 1: I'm asking, like, how big is it? Is it bigger

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Speaker 1: than Jupiter? Is it smaller than Jupiter? What's the diameter

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Speaker 1: of this smallest sun?

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Speaker 2: So these things are not actually much bigger than Jupiter

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Speaker 2: because as you add more mass to them, they just

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Speaker 2: get denser and denser, in the same way that like

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Speaker 2: a rocky planet can't get much bigger than Earth. It

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Speaker 2: just gets denser and denser. There are stars out there

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Speaker 2: whose radius is not much bigger than Jupiter, but they

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Speaker 2: are burning. There are red dwarfs, and they have fusion

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Speaker 2: at their core, so they wouldn't be much larger than Jupiter.

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Speaker 2: They're just a lot more massive.

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Speaker 1: Interesting, so the lower limit for the size of a

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Speaker 1: star is about the size of Jupiter.

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Speaker 2: Then yeah, order magnitude Jupiter. So you couldn't have a

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Speaker 2: solar system the size of marbles, but you could have

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Speaker 2: a Jupiter sized star at the heart of a solar system.

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Speaker 1: But then what is a brown dwarf.

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Speaker 2: Yeah, so if you require the kind of fusion that

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Speaker 2: happens at the heart of our star, like true fusion,

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Speaker 2: then you need that much mass. But it is possible

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Speaker 2: to have a different kind into fusion happening at the

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Speaker 2: heart of a star, called deuterium fusion, and this happens

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Speaker 2: sometimes in objects we call brown dwarfs, which are just

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Speaker 2: like big jupiters. You have like ten times the mass

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Speaker 2: of Jupiter, then you can get this other kind of

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Speaker 2: nuclear fusion going where deuterium and protons combined to make

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Speaker 2: helium three and it releases a little bit of heat,

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Speaker 2: but it's not as hot and not as productive as

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Speaker 2: the kind of fusion that happens at the heart of

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Speaker 2: our star. So brown dwarfs are called brown because they

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Speaker 2: don't like glow. They don't give off photons the same

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Speaker 2: way that red dwarfs, and like yellow stars like our sun, dom.

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Speaker 1: So they're more like simmering, but they're still burning inside.

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Speaker 1: So what do they look like from the outside of

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Speaker 1: your standing next to one, like a glowy Jupiter or what.

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Speaker 2: There's a whole range of course of brown dwarfs from

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Speaker 2: low temperature to higher temperatures. Some of them do glow.

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Speaker 2: They don't glow as bright as the Sun, but they

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Speaker 2: do glow brighter than Jupiter of course, And of course

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Speaker 2: Jupiter gives off a lot of radiation on its own,

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Speaker 2: but not like a brown dwarf. So yeah, it'd be

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Speaker 2: sort of like intermediate between Jupiter and an actual sun.

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Speaker 1: And how big would those be?

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Speaker 2: Those are again not much bigger than Jupiter, right, because

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Speaker 2: as you keep adding masks, it doesn't get larger, it

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Speaker 2: just gets denser.

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Speaker 1: But it would maybe only be like ten times more

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Speaker 1: massive than Jupiter, in which case, like a solar system

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Speaker 1: with a star like that would maybe look a lot

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Speaker 1: like Jupiter with its moods.

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Speaker 2: Yeah, exactly, something like that. So definitely not marble sized,

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Speaker 2: but smaller than our solar system for sure.

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Speaker 1: And would that sun give enough light to maybe sustain

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Speaker 1: life or I guess it depends on what kind of life.

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Speaker 2: There's a lot of debate about whether you can have

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Speaker 2: life around a brown dwarf, whether there is a sort

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Speaker 2: of a habitable zone around there. I don't think we

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Speaker 2: know enough about brown dwarfs to say for sure.

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Speaker 1: M I guess it maybe depends on the size of

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Speaker 1: the planet, which is sort of Tim's other part of

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Speaker 1: the question, which is maybe what's the smallest planet you

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Speaker 1: could have.

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Speaker 2: Yeah, this is a really interesting question, and it sort

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Speaker 2: of comes down to the nature of like how you

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Speaker 2: define a planet and also like how things get right

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Speaker 2: because there's a lot of stuff out there in the

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Speaker 2: Solar System. You know, there's rocks like the Earth, but

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Speaker 2: there's also tiny little rocks just floating out there all

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Speaker 2: the way down from asteroids to meteoroids to just like

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Speaker 2: grains of dust, And you might ask, like, could you

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Speaker 2: consider all those things planets. Well, we have requirements for

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Speaker 2: what a planet is. Planets have to orbit the Sun,

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Speaker 2: not some other object, which is like why the Moon

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Speaker 2: is not a planet. They also have to have enough

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Speaker 2: gravity to make themselves round, like if you're long in

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Speaker 2: cigar shaped, you're not a planet. This is a way

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Speaker 2: to avoid calling every tiny piece of dust that's orbiting

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Speaker 2: the Solar system of planet. And then the last requirement

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Speaker 2: is that has to clear its neighborhood, has to be

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Speaker 2: like the dominant gravitational thing in its neighborhood. And so

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Speaker 2: that sort of sets an effective minimum size for a planet.

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Speaker 1: What would be that size? How many kilometers?

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Speaker 2: Yeah, it's interesting. It depends a little bit on what

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Speaker 2: it's made out of. Like, first of all, like why

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Speaker 2: does gravity make things round? Well, gravity makes things round

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Speaker 2: because it likes to pull stuff down. You know, imagine

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Speaker 2: a spherical planet, then you put a very tall mountain

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Speaker 2: on it. Eventually gravity is going to pull that mountain down,

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Speaker 2: especially if there's weathering effects on the planet that shake

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Speaker 2: things or tectonics, et cetera.

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Speaker 1: And by down you mean like the center of whatever

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Speaker 1: it is.

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Speaker 2: Right mm hmmm yeah, And so sphere is like the

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Speaker 2: gravitationally most stable object. If something is a perfect sphere,

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Speaker 2: there's nowhere for anything to fall further down. So gravity

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Speaker 2: likes to make things round, but it can't always do that, right,

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Speaker 2: Like you take a pencil, a pencil has its own gravity,

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Speaker 2: but not enough for gravity to make it into like

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Speaker 2: a round ball. Right, So the amount of stuff you

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Speaker 2: need in order to become round also depends a little

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Speaker 2: bit on your mass. So as things get bigger, they

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Speaker 2: have more gravity, and then gravity can overcome the internal

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Speaker 2: strength of an object and make it round. And so

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Speaker 2: there's this size called like the potato radius, around which

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Speaker 2: gravity starts to round things out.

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Speaker 1: I feel though that maybe that's a like a very

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Speaker 1: human set a definition of a planet, Like we just

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Speaker 1: want our planets to be round. But I wonder if

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Speaker 1: there could be, you know, some body out there is

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Speaker 1: some oddly shaped asteroid or giant rock that maybe has

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Speaker 1: evolved life, and then those aliens would call their little

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Speaker 1: rock a planet, right, or at least they would call

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Speaker 1: it home.

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Speaker 2: For sure. Our definition of planet is human centric. We

401
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Speaker 2: made this thing up, and you're right weak interested in

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Speaker 2: planets because that's the first thing we noticed. We live

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Speaker 2: on one. To us, it's the most important part of

404
00:19:28,600 --> 00:19:31,000
Speaker 2: the Solar System. In reality, the Solar System is failed

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Speaker 2: the huge, beautiful spectrum of different shaped objects. And this

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00:19:35,800 --> 00:19:38,880
Speaker 2: is just like people drawing dotted lines around certain kinds

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Speaker 2: of them and then trying to defend those dotted lines

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Speaker 2: even though they're ridiculous and arbitrary. Yeah, you could probably

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Speaker 2: have life form on not around objects and then those

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00:19:46,720 --> 00:19:51,120
Speaker 2: aliens might think that our distinction is arbitrary. But you know,

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Speaker 2: Tim is a human. He's asking questions from a human perspective.

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Speaker 1: Is he?

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Speaker 2: Now, I'm not veteretan.

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Speaker 1: I mean, if I'm so tiny, then maybe he's.

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Speaker 2: But the minimum size to make something round if you're

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Speaker 2: like made of ice or water is like four hundred kilometers.

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Speaker 2: That's when things tend to form like potato shapes. If

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Speaker 2: you're made of rock, it's about twice that big, and

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Speaker 2: so you need like eight hundred kilometer wide. Stuff tend

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Speaker 2: to be pretty round. So that's like the minimum size

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Speaker 2: for an object for gravity to make it roundish ooh.

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Speaker 1: Well, I feel like maybe also are your definition of

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Speaker 1: a sun is also the human centric because that's what

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Speaker 1: happens in our sun is the regular kind of fusion.

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Speaker 1: But aren't some stars out there at that astronomers call stars,

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Speaker 1: aren't they just like really hot rocks.

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Speaker 2: Well, there are objects out there called white dwarfs, which

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00:20:44,400 --> 00:20:48,240
Speaker 2: are the remnants of stars. They're not burning anymore, there's

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Speaker 2: no fusion happening at their core. They're leftover bits of

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Speaker 2: stars that have ended their life. And those are called

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Speaker 2: like white dwarfs.

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Speaker 1: And you can see them in the night sky sometimes, right.

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Speaker 2: I don't know that you can see them with the

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Speaker 2: naked eye. We have detected a few of them, but

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Speaker 2: they're pretty hard because they don't glow the same way

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Speaker 2: that other stars do.

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Speaker 1: But you still call them stars though, right, because they're

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Speaker 1: emitting a lot of radiation.

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Speaker 2: They do emit a lot of radiation. I don't know

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Speaker 2: if astronomers would call them stars or stellar remnants, but yeah,

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Speaker 2: they're definitely related to stars.

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00:21:19,480 --> 00:21:21,520
Speaker 1: Because I wonder if you can just have maybe like

443
00:21:21,560 --> 00:21:25,320
Speaker 1: a super duper hot marvel out there in space, and

444
00:21:25,359 --> 00:21:28,600
Speaker 1: then have really really tiny marbles orbiting around that hot marble,

445
00:21:28,680 --> 00:21:31,199
Speaker 1: and then maybe you can call that a solar system,

446
00:21:31,880 --> 00:21:34,920
Speaker 1: and maybe things have evolved in those teeny tiny marble

447
00:21:34,960 --> 00:21:39,960
Speaker 1: planets and they're living in their little marble existence, marveling

448
00:21:39,960 --> 00:21:41,080
Speaker 1: at how small they are.

449
00:21:42,200 --> 00:21:45,000
Speaker 2: Yeah, that's certainly possible. You could take a scoop of

450
00:21:45,080 --> 00:21:48,920
Speaker 2: neutron star material, right, that'd be a hot blob of stuff,

451
00:21:49,400 --> 00:21:52,480
Speaker 2: and you could put a few rocks in orbit around it,

452
00:21:53,119 --> 00:21:54,800
Speaker 2: and you could call that a solar system.

453
00:21:54,520 --> 00:21:56,680
Speaker 1: Sure, right, and then the thing in the middle of

454
00:21:56,680 --> 00:21:58,399
Speaker 1: the hot stuff in the middle would be admitting light and

455
00:21:58,440 --> 00:22:01,359
Speaker 1: that might sustain life in those little tiny rocks or

456
00:22:01,400 --> 00:22:02,000
Speaker 1: being around it.

457
00:22:02,800 --> 00:22:05,119
Speaker 2: Yeah. Absolutely. I don't know how long that would last

458
00:22:05,200 --> 00:22:06,920
Speaker 2: because you don't have that much stuff, and so it's

459
00:22:06,920 --> 00:22:09,360
Speaker 2: going to radiate its heat out pretty fast. I don't

460
00:22:09,359 --> 00:22:11,680
Speaker 2: know if there's really time for life to evolve under

461
00:22:11,720 --> 00:22:14,760
Speaker 2: those circumstances. But you know, if you're setting up a

462
00:22:14,800 --> 00:22:18,040
Speaker 2: little vivarium in space, you could put some microbes on

463
00:22:18,119 --> 00:22:19,359
Speaker 2: there and then you could say, hey, look, I have

464
00:22:19,400 --> 00:22:20,679
Speaker 2: a solar system with life on it.

465
00:22:20,840 --> 00:22:24,280
Speaker 1: Yeah. Yeah, it'd be like instead of sea monkeys, the space.

466
00:22:24,040 --> 00:22:26,800
Speaker 2: Monkeys exactly, space monkeys.

467
00:22:27,119 --> 00:22:29,320
Speaker 1: Well, it sounds like the answer for tim is that

468
00:22:29,480 --> 00:22:32,080
Speaker 1: you could have a teeny tiny marble sized solar system.

469
00:22:32,160 --> 00:22:35,080
Speaker 1: Like that's technically possible if you make it, but maybe

470
00:22:35,440 --> 00:22:39,480
Speaker 1: naturally occurring. It'd be kind of uh hard to find

471
00:22:39,480 --> 00:22:40,120
Speaker 1: something like that.

472
00:22:40,520 --> 00:22:44,800
Speaker 2: Yeah. The universe has certain scales because of the forces

473
00:22:44,840 --> 00:22:47,960
Speaker 2: of gravity and the strength of other materials. Gives us

474
00:22:48,000 --> 00:22:52,080
Speaker 2: a minimum size for stars and a minimum size for planets.

475
00:22:52,520 --> 00:22:54,679
Speaker 2: I think that's really interesting and it really does reveal

476
00:22:54,760 --> 00:22:57,880
Speaker 2: something about the balance of the various forces in our universe.

477
00:22:58,160 --> 00:23:03,000
Speaker 1: Yeah, because in the end, everything is limited by physics, right,

478
00:23:03,200 --> 00:23:04,159
Speaker 1: not our imagination.

479
00:23:04,400 --> 00:23:05,840
Speaker 2: I'm certainly limited by physics.

480
00:23:05,920 --> 00:23:08,400
Speaker 1: Yeah, all right, well, thanks Tim for that question. Let's

481
00:23:08,440 --> 00:23:11,720
Speaker 1: get to our next question, and this one is about

482
00:23:11,960 --> 00:23:15,240
Speaker 1: the Greeks and what they knew about the universe, So

483
00:23:15,440 --> 00:23:18,320
Speaker 1: we'll dig into that, but first let's take a quick break.

484
00:23:31,000 --> 00:23:31,119
Speaker 3: Right.

485
00:23:31,160 --> 00:23:33,760
Speaker 1: We're answering listener questions here today, and our next question

486
00:23:33,960 --> 00:23:35,080
Speaker 1: comes from Michael.

487
00:23:36,160 --> 00:23:38,400
Speaker 4: I thought about an off hand comment you made many

488
00:23:38,400 --> 00:23:41,359
Speaker 4: episodes ago about things we still don't understand that the

489
00:23:41,359 --> 00:23:45,199
Speaker 4: ancient Greeks didn't understand. So my question tonight is what

490
00:23:45,240 --> 00:23:47,679
Speaker 4: are the three most opique things we still don't have

491
00:23:47,720 --> 00:23:50,199
Speaker 4: a good answer for since the Greeks, and what is

492
00:23:50,359 --> 00:23:53,199
Speaker 4: our best understanding of them now? And what was the

493
00:23:53,240 --> 00:23:55,359
Speaker 4: most common ancient understanding of them?

494
00:23:56,080 --> 00:23:56,159
Speaker 2: All?

495
00:23:56,280 --> 00:24:01,960
Speaker 1: Right, awesome question from Michael. He's basically asking what is

496
00:24:01,960 --> 00:24:03,720
Speaker 1: still all Greek to us?

497
00:24:05,960 --> 00:24:08,240
Speaker 2: Yeah, apparently I made some comment about how there are

498
00:24:08,240 --> 00:24:11,720
Speaker 2: still questions we haven't answered that the Greek's puzzled about,

499
00:24:12,080 --> 00:24:14,320
Speaker 2: which is super awesome because it just means that some

500
00:24:14,359 --> 00:24:17,399
Speaker 2: of these questions are timeless. It also excites me to

501
00:24:17,440 --> 00:24:20,840
Speaker 2: imagine that one day we might know the answers that

502
00:24:20,920 --> 00:24:23,760
Speaker 2: in the future. Physicists and philosophers could look back at

503
00:24:23,840 --> 00:24:27,679
Speaker 2: Us and lump Us in with like Aristotle as the clueless,

504
00:24:27,960 --> 00:24:32,199
Speaker 2: pre knowledge kind of human before we really understood how

505
00:24:32,240 --> 00:24:32,760
Speaker 2: things were.

506
00:24:33,119 --> 00:24:35,080
Speaker 1: I see. Well, in that case, would being called the

507
00:24:35,119 --> 00:24:38,399
Speaker 1: Aristotle of the twenty first century be a good thing

508
00:24:38,480 --> 00:24:38,919
Speaker 1: or a bad thing?

509
00:24:39,080 --> 00:24:39,199
Speaker 2: Oh?

510
00:24:39,320 --> 00:24:39,520
Speaker 3: Yeah?

511
00:24:39,560 --> 00:24:41,800
Speaker 2: Being the Aristotle of anything would be awesome? Well that

512
00:24:42,119 --> 00:24:45,959
Speaker 2: is super smart? Yeah, yeah, yeah, I wouldn't mind being

513
00:24:45,960 --> 00:24:49,520
Speaker 2: the Aristotle of baking. I could be the Aristotle of naps.

514
00:24:49,760 --> 00:24:50,680
Speaker 2: That sounds wonderful.

515
00:24:51,200 --> 00:24:55,840
Speaker 1: You do it in a toga anyways? Right, all right, Well,

516
00:24:56,000 --> 00:24:59,680
Speaker 1: I guess Michael's question is kind of a little bit straightforward.

517
00:24:59,680 --> 00:25:02,199
Speaker 1: He saying, what did we not know back then when

518
00:25:02,240 --> 00:25:04,760
Speaker 1: the Greeks were hanging on and thinking about the universe

519
00:25:04,880 --> 00:25:06,280
Speaker 1: that we still don't know today?

520
00:25:06,800 --> 00:25:10,199
Speaker 2: Yeah, great question, Michael on The answer is pretty basic stuff,

521
00:25:10,880 --> 00:25:14,280
Speaker 2: you know, questions that like your kids might ask you. So,

522
00:25:14,480 --> 00:25:17,119
Speaker 2: question number one is like, how did the universe come

523
00:25:17,160 --> 00:25:19,119
Speaker 2: to be? Did it come to be?

524
00:25:19,440 --> 00:25:19,600
Speaker 3: Right?

525
00:25:19,720 --> 00:25:22,040
Speaker 2: Really? What is the age of the universe? What is

526
00:25:22,080 --> 00:25:25,719
Speaker 2: its origin? This is not something we know the answer to,

527
00:25:25,800 --> 00:25:28,600
Speaker 2: and definitely something the Greeks didn't understand.

528
00:25:29,560 --> 00:25:32,040
Speaker 1: Is there a record of the Greeks asking this question

529
00:25:32,200 --> 00:25:33,119
Speaker 1: or wondering about it.

530
00:25:33,359 --> 00:25:37,320
Speaker 2: Oh, absolutely, and a lot of Greek mythology tries to

531
00:25:37,359 --> 00:25:41,159
Speaker 2: explain how they thought the universe came to be. But

532
00:25:41,280 --> 00:25:43,919
Speaker 2: their answers were not at all scientific, you know, as

533
00:25:44,000 --> 00:25:46,680
Speaker 2: much as the Greeks made progress in trying to understand

534
00:25:46,680 --> 00:25:49,520
Speaker 2: the nature of the universe around them, the answers to

535
00:25:49,560 --> 00:25:52,000
Speaker 2: the question of the origin of the universe really read

536
00:25:52,119 --> 00:25:55,439
Speaker 2: like pure mythology. You know, they talk about gods that

537
00:25:55,560 --> 00:25:59,800
Speaker 2: created the air, a god named Chaos, and then another

538
00:26:00,200 --> 00:26:04,280
Speaker 2: that created the earth, and you know, created Mount Olympus,

539
00:26:04,680 --> 00:26:07,560
Speaker 2: and then battles between these gods that formed the earth

540
00:26:07,600 --> 00:26:10,560
Speaker 2: that they know about, and then came forth darkness, and

541
00:26:10,600 --> 00:26:13,399
Speaker 2: then came forth the night. The whole thing just reads

542
00:26:13,560 --> 00:26:14,760
Speaker 2: like pure mythology.

543
00:26:16,359 --> 00:26:19,480
Speaker 1: But I guess that's mythology and religion in Greek times.

544
00:26:19,520 --> 00:26:23,639
Speaker 1: But I wonder if everyone back then believe these things,

545
00:26:24,320 --> 00:26:27,760
Speaker 1: or did, maybe like Aristotle, think have other questions or

546
00:26:27,800 --> 00:26:30,040
Speaker 1: maybe other theories about the beginning of the universe.

547
00:26:30,320 --> 00:26:33,520
Speaker 2: It's certainly not possible to know for sure what all

548
00:26:33,640 --> 00:26:35,840
Speaker 2: the Greeks thought about these things, because remember, we have

549
00:26:35,880 --> 00:26:39,679
Speaker 2: a tiny fragment of all the Greek writing the Greeks

550
00:26:39,680 --> 00:26:42,040
Speaker 2: were very prolific, thought about lots of things, wrote about

551
00:26:42,040 --> 00:26:44,280
Speaker 2: a lot of things. And when we talk about our

552
00:26:44,320 --> 00:26:46,880
Speaker 2: knowledge of the Greeks, we talk about what has survived,

553
00:26:47,400 --> 00:26:50,160
Speaker 2: and that's really a tiny fraction of everything that was written.

554
00:26:50,560 --> 00:26:53,199
Speaker 2: And in many cases we have only like references to

555
00:26:53,359 --> 00:26:57,399
Speaker 2: discussions about other topics that Aristotle mentioned. I'm sure that

556
00:26:57,440 --> 00:26:59,960
Speaker 2: there are people thinking about the origin of the universe

557
00:27:00,200 --> 00:27:03,040
Speaker 2: in Greek times that we have not captured. And actually

558
00:27:03,080 --> 00:27:05,800
Speaker 2: we live right now at a very exciting moment because

559
00:27:05,840 --> 00:27:09,600
Speaker 2: we're using new technology to read ancient scroll that have

560
00:27:09,680 --> 00:27:12,320
Speaker 2: never been read before, ones that were burned in fire

561
00:27:12,440 --> 00:27:16,200
Speaker 2: and in volcanic destructions, where we have like the Charred Scroll,

562
00:27:16,320 --> 00:27:18,359
Speaker 2: but we never have read it before because if you

563
00:27:18,440 --> 00:27:20,359
Speaker 2: try to open it up, it just falls apart. And

564
00:27:20,400 --> 00:27:23,320
Speaker 2: now to have new scanning technology that can read the

565
00:27:23,359 --> 00:27:26,560
Speaker 2: scrolls without unrolling them, and so for the first time

566
00:27:26,560 --> 00:27:30,000
Speaker 2: we're discovering huge numbers of new Greek writings, which is

567
00:27:30,040 --> 00:27:32,920
Speaker 2: going to change completely our understanding of what the Greeks thought.

568
00:27:33,480 --> 00:27:37,240
Speaker 2: But that said, even Aristotle and these other guys, they're

569
00:27:37,240 --> 00:27:40,040
Speaker 2: basically philosophers, and at the time these were the cutting

570
00:27:40,119 --> 00:27:42,320
Speaker 2: edge ideas for how the universe came to be?

571
00:27:42,720 --> 00:27:45,600
Speaker 1: Right, right, Well, I wonder if he had asked Aristotle

572
00:27:45,840 --> 00:27:47,800
Speaker 1: so he thought the universe began? What do you think

573
00:27:47,800 --> 00:27:50,359
Speaker 1: he would say? Would he say zeus or would he

574
00:27:50,400 --> 00:27:51,399
Speaker 1: say beats me?

575
00:27:51,680 --> 00:27:53,959
Speaker 2: I suspect the Aristotle would say that he didn't know.

576
00:27:54,720 --> 00:27:58,120
Speaker 2: I mean, Aristotle and the Greeks had trouble even conceiving

577
00:27:58,320 --> 00:28:01,720
Speaker 2: of the cosmos. Like this question, we're asking, where did

578
00:28:01,760 --> 00:28:04,560
Speaker 2: the universe come from? They didn't even really understand the

579
00:28:04,680 --> 00:28:07,320
Speaker 2: universe the same way that we do. They mostly thought

580
00:28:07,320 --> 00:28:10,880
Speaker 2: about the Earth and the Solar System and a few stars.

581
00:28:10,920 --> 00:28:13,439
Speaker 2: They had no concept for even like how big the

582
00:28:13,560 --> 00:28:16,520
Speaker 2: universe was, which we'll talk about in a minute. So

583
00:28:16,560 --> 00:28:18,600
Speaker 2: it's sort of like asking him a question. It wouldn't

584
00:28:18,600 --> 00:28:20,240
Speaker 2: even understand the question.

585
00:28:20,280 --> 00:28:22,720
Speaker 1: Right because they just didn't know as much as we

586
00:28:22,800 --> 00:28:23,280
Speaker 1: do now.

587
00:28:23,480 --> 00:28:26,879
Speaker 2: Yeah, exactly, And yet even today we still don't have

588
00:28:26,920 --> 00:28:29,440
Speaker 2: an answer to this question. We have a few ideas

589
00:28:29,440 --> 00:28:31,720
Speaker 2: for where the universe came from. We know at least

590
00:28:31,760 --> 00:28:34,600
Speaker 2: how old it is, like we can date the evolution

591
00:28:34,760 --> 00:28:38,520
Speaker 2: of the universe back almost fourteen billion years. That's often

592
00:28:38,640 --> 00:28:41,160
Speaker 2: quoted as the age of the universe, but we really

593
00:28:41,160 --> 00:28:43,760
Speaker 2: don't know what came before that. We don't know if

594
00:28:43,800 --> 00:28:47,000
Speaker 2: there was a singularity and the universe was burst somehow

595
00:28:47,080 --> 00:28:49,920
Speaker 2: just before that, as general relativity says, or if there

596
00:28:49,960 --> 00:28:53,360
Speaker 2: was some other weird state that predated that early hot

597
00:28:53,440 --> 00:28:56,240
Speaker 2: moment that we can describe, and the universe was like

598
00:28:56,320 --> 00:28:59,760
Speaker 2: infinitely old before that in just some other form that's

599
00:28:59,800 --> 00:29:03,960
Speaker 2: now beyond our understanding and capacity to describe. So we

600
00:29:04,000 --> 00:29:07,160
Speaker 2: still don't have any idea really how the universe came

601
00:29:07,200 --> 00:29:10,040
Speaker 2: to be, how long it's been around. We do have

602
00:29:10,080 --> 00:29:12,560
Speaker 2: some concept for at least how old it must be,

603
00:29:13,640 --> 00:29:16,760
Speaker 2: so that's something. But we're still struggling to answer this

604
00:29:16,920 --> 00:29:19,040
Speaker 2: very basic question that the Greeks wondered about.

605
00:29:19,680 --> 00:29:21,960
Speaker 1: Wait, wait, are you saying that maybe the Greeks could

606
00:29:22,000 --> 00:29:25,440
Speaker 1: still be right? He said that maybe it's all chaos

607
00:29:25,440 --> 00:29:29,000
Speaker 1: before the big bank like make them correct.

608
00:29:29,280 --> 00:29:31,320
Speaker 2: I mean, in principle, it could all just be some

609
00:29:31,440 --> 00:29:36,200
Speaker 2: simulation run by external superintelligent beings and you could call

610
00:29:36,240 --> 00:29:38,840
Speaker 2: those the Greek gods. So yeah, I guess in that sense,

611
00:29:38,840 --> 00:29:40,040
Speaker 2: the Greeks could still be right.

612
00:29:40,520 --> 00:29:42,560
Speaker 1: All right, Well, what's another question that we know that

613
00:29:42,600 --> 00:29:44,560
Speaker 1: they were asking that we're still asking today.

614
00:29:44,720 --> 00:29:48,320
Speaker 2: Another question is how much of the universe is there? Right?

615
00:29:48,400 --> 00:29:51,680
Speaker 2: How big is the universe? And it's really fun to

616
00:29:51,680 --> 00:29:54,360
Speaker 2: dig into like what the Greeks thought about the universe,

617
00:29:54,440 --> 00:29:57,960
Speaker 2: because the Greeks were really careful and trying to understand

618
00:29:58,080 --> 00:30:00,600
Speaker 2: the nature of the Solar System, the Earth, and the

619
00:30:00,600 --> 00:30:04,240
Speaker 2: planets in the sun. They're very geometrical, very mathematical about

620
00:30:04,240 --> 00:30:07,560
Speaker 2: what they saw happening in the night sky. But then

621
00:30:07,600 --> 00:30:10,040
Speaker 2: it's very difficult for them to think much beyond that,

622
00:30:10,360 --> 00:30:13,480
Speaker 2: for them to cast their minds and understand how big

623
00:30:13,520 --> 00:30:14,840
Speaker 2: the universe really was.

624
00:30:15,440 --> 00:30:18,040
Speaker 1: Right, Well, back then, did they believe that the Earth

625
00:30:18,080 --> 00:30:19,800
Speaker 1: was the center of the universe and that the Sun

626
00:30:19,880 --> 00:30:21,200
Speaker 1: went around the Earth?

627
00:30:21,320 --> 00:30:23,840
Speaker 2: Yeah? Absolutely, they thought the Earth was the center of

628
00:30:23,920 --> 00:30:27,680
Speaker 2: the Solar system and everything went around the Earth. And

629
00:30:27,760 --> 00:30:30,000
Speaker 2: the reason they thought this is not because they were stupid,

630
00:30:30,400 --> 00:30:33,120
Speaker 2: it's actually because they had a misunderstanding of how big

631
00:30:33,160 --> 00:30:37,920
Speaker 2: the universe was. Like they considered the idea that maybe

632
00:30:38,040 --> 00:30:40,680
Speaker 2: the Earth and all the other planets went around the Sun. Absolutely,

633
00:30:41,160 --> 00:30:44,200
Speaker 2: and they're thinking was, well, if that's true, then we

634
00:30:44,240 --> 00:30:47,000
Speaker 2: should see the stars move in the sky. And they

635
00:30:47,000 --> 00:30:49,840
Speaker 2: were right, because as the Earth moves around the Sun,

636
00:30:49,920 --> 00:30:52,000
Speaker 2: we do see the stars wiggle in the sky. It's

637
00:30:52,000 --> 00:30:55,120
Speaker 2: called the parallax effect, like we have a different perspective

638
00:30:55,160 --> 00:30:57,040
Speaker 2: on the stars from one side of the Sun and

639
00:30:57,080 --> 00:30:59,120
Speaker 2: the other. They looked up at the stars and they

640
00:30:59,120 --> 00:31:01,680
Speaker 2: didn't see any whigs because they didn't yet have the

641
00:31:01,720 --> 00:31:04,640
Speaker 2: capacity to see the tiny wiggles of the star. The

642
00:31:04,680 --> 00:31:07,800
Speaker 2: parallax effect was too small for humans to detect until

643
00:31:07,840 --> 00:31:10,680
Speaker 2: like the eighteenth century. So they concluded from that the

644
00:31:10,720 --> 00:31:12,640
Speaker 2: Earth was not moving around the Sun.

645
00:31:12,920 --> 00:31:15,520
Speaker 1: Whoa, they actually had like data to back this up.

646
00:31:15,720 --> 00:31:19,080
Speaker 2: Yeah, exactly. Their mistake was they thought the stars were

647
00:31:19,120 --> 00:31:23,200
Speaker 2: super duper close and so the parallax should be pretty obvious. Actually,

648
00:31:23,200 --> 00:31:25,680
Speaker 2: the stars are much much further away than they could

649
00:31:25,760 --> 00:31:29,120
Speaker 2: even conceive of, and so while the parallax effect is there,

650
00:31:29,200 --> 00:31:32,000
Speaker 2: the stars are wiggling in the sky, they just couldn't

651
00:31:32,000 --> 00:31:35,360
Speaker 2: see it. So their mistake in thinking that the stars

652
00:31:35,360 --> 00:31:38,040
Speaker 2: were much closer than they were is actually what led

653
00:31:38,080 --> 00:31:41,240
Speaker 2: them to misunderstand the structure of our solar system. But

654
00:31:41,320 --> 00:31:43,640
Speaker 2: it was very logical and very reasonable.

655
00:31:43,920 --> 00:31:46,840
Speaker 1: Like just one tiny assumption, right, Like one assumption in

656
00:31:46,880 --> 00:31:48,960
Speaker 1: their thinking and can really throw you off.

657
00:31:49,080 --> 00:31:52,120
Speaker 2: Mm hm. And yet they also knew that the Earth

658
00:31:52,320 --> 00:31:55,120
Speaker 2: was tiny. We have evidence in their writing, like Marcus

659
00:31:55,120 --> 00:31:58,040
Speaker 2: Aurelius said that, quote, the whole Earth is a point

660
00:31:58,080 --> 00:32:01,720
Speaker 2: in space, and Aristotle described the Earth as quote no

661
00:32:01,920 --> 00:32:05,720
Speaker 2: great size relative to the cosmos. So they knew that

662
00:32:05,800 --> 00:32:08,920
Speaker 2: the Earth was a tiny dot in space. They just

663
00:32:08,920 --> 00:32:12,320
Speaker 2: couldn't even conceive of how big that space actually was.

664
00:32:13,960 --> 00:32:16,040
Speaker 1: They knew it was a dot, but actually it's like

665
00:32:16,080 --> 00:32:17,960
Speaker 1: a super duper tiny micro.

666
00:32:17,800 --> 00:32:21,280
Speaker 2: Dot exactly, It's like a dot of a dot. And

667
00:32:21,360 --> 00:32:24,240
Speaker 2: today we know that the universe is much vaster than

668
00:32:24,240 --> 00:32:27,239
Speaker 2: they could conceive of, at least ninety two billion light

669
00:32:27,360 --> 00:32:30,400
Speaker 2: years across, And yet we don't know if that entire

670
00:32:30,400 --> 00:32:34,600
Speaker 2: observable universe is just a dot in some much vaster universe,

671
00:32:34,680 --> 00:32:38,880
Speaker 2: potentially even infinite. So we basically have no clue as

672
00:32:38,920 --> 00:32:41,480
Speaker 2: to the absolute answer to this question of how big

673
00:32:41,600 --> 00:32:42,400
Speaker 2: is the universe?

674
00:32:42,840 --> 00:32:46,040
Speaker 1: No, I see so like proportionally like, if the size

675
00:32:46,040 --> 00:32:49,480
Speaker 1: of the possible universe is from zero to infinity, we're

676
00:32:49,520 --> 00:32:54,880
Speaker 1: still pretty clueless because infinity is infinity. So we have

677
00:32:54,920 --> 00:32:57,160
Speaker 1: no idea. Right it could be that we have as

678
00:32:57,320 --> 00:32:59,920
Speaker 1: much of an idea plus or minus a few percent

679
00:33:00,080 --> 00:33:01,200
Speaker 1: the Greeks.

680
00:33:01,000 --> 00:33:03,560
Speaker 2: Well, you know, in the same whether we've made progress

681
00:33:03,560 --> 00:33:05,600
Speaker 2: and understanding the age of the universe. We know at

682
00:33:05,680 --> 00:33:08,280
Speaker 2: least how old it is, and we know at least

683
00:33:08,320 --> 00:33:11,280
Speaker 2: how big the universe is, So we've made some measurable progress.

684
00:33:11,440 --> 00:33:13,479
Speaker 2: But you're right, that could be a zero percent fraction

685
00:33:13,640 --> 00:33:15,360
Speaker 2: of the actual size of the universe.

686
00:33:15,600 --> 00:33:18,760
Speaker 1: All right, great question for Michael. It sounds like we

687
00:33:18,800 --> 00:33:21,240
Speaker 1: still have a lot that we haven't figured out since

688
00:33:21,320 --> 00:33:21,800
Speaker 1: the Greeks.

689
00:33:22,040 --> 00:33:24,560
Speaker 2: Yeah, if we had Aristotle over for dinner, we could

690
00:33:24,560 --> 00:33:26,240
Speaker 2: teach him a bunch of stuff, But I think in

691
00:33:26,280 --> 00:33:30,840
Speaker 2: the end he would still be unsatisfied because his fundamental

692
00:33:30,880 --> 00:33:32,840
Speaker 2: questions have not yet been answered.

693
00:33:32,920 --> 00:33:34,280
Speaker 1: Well, I feel like he would just spend the whole

694
00:33:34,320 --> 00:33:36,239
Speaker 1: night playing with your iPhone. He'd be like, what is

695
00:33:36,280 --> 00:33:36,960
Speaker 1: this magic?

696
00:33:37,360 --> 00:33:40,520
Speaker 2: I what now? He'd probably fall for our phishing scheme

697
00:33:40,640 --> 00:33:43,360
Speaker 2: immediately and send all of our money to Nigeria or something.

698
00:33:43,600 --> 00:33:45,840
Speaker 1: He'd be watching YouTube all night. Probably.

699
00:33:46,760 --> 00:33:49,440
Speaker 2: It makes me wonder if I had dinner with physicists

700
00:33:49,480 --> 00:33:51,640
Speaker 2: from one thousand or two thousand years in the future,

701
00:33:51,840 --> 00:33:54,360
Speaker 2: would they have answers to these questions? Would they have

702
00:33:54,440 --> 00:33:58,800
Speaker 2: made measurable progress but still have no real fundamental answers.

703
00:33:59,200 --> 00:34:01,360
Speaker 2: That's exhilarating, but also potentially frustrating.

704
00:34:01,720 --> 00:34:03,800
Speaker 1: Nice, and that's why you want to freeze yourself, right,

705
00:34:04,040 --> 00:34:06,520
Speaker 1: Oh yeah, absolutely, let's do it just for that dinner

706
00:34:06,640 --> 00:34:08,880
Speaker 1: date in the future, multiple dinner date. Do you have

707
00:34:08,920 --> 00:34:13,719
Speaker 1: the book it now, I'm gonna leave it. I'm gonna

708
00:34:13,760 --> 00:34:15,759
Speaker 1: have dinner with your great great great great great great

709
00:34:15,800 --> 00:34:19,320
Speaker 1: great great grandkids. It's on the calendar. Yeah, don't forget.

710
00:34:19,440 --> 00:34:22,239
Speaker 1: I sent them a calendar invite. Absolutely, don't forget. To

711
00:34:22,239 --> 00:34:23,200
Speaker 1: defrost me. Please.

712
00:34:24,239 --> 00:34:26,839
Speaker 2: My daughter sends me calendar invites for like ten years

713
00:34:26,840 --> 00:34:29,320
Speaker 2: in the future or thirty years in the future.

714
00:34:29,680 --> 00:34:31,880
Speaker 1: Oh yeah, for like asking you for money.

715
00:34:32,080 --> 00:34:33,840
Speaker 2: Yeah, like buy Hazel a car.

716
00:34:34,000 --> 00:34:35,560
Speaker 1: Say hey, Dad, buy me a car in.

717
00:34:35,880 --> 00:34:38,440
Speaker 2: Five years, Yeah, exactly.

718
00:34:39,080 --> 00:34:41,520
Speaker 1: All right, well, thank you, Michael. Now let's get to

719
00:34:41,560 --> 00:34:45,040
Speaker 1: our last question, which is about whether a tiny black

720
00:34:45,080 --> 00:34:48,839
Speaker 1: hole could still destroy the Earth. And so let's get

721
00:34:48,880 --> 00:34:51,760
Speaker 1: it to that question. But first let's take another quick break.

722
00:35:04,520 --> 00:35:04,640
Speaker 3: Right.

723
00:35:04,640 --> 00:35:06,680
Speaker 1: We're answering listener questions here to the and our last

724
00:35:06,760 --> 00:35:11,239
Speaker 1: question is about the destruction of our planet by a

725
00:35:11,280 --> 00:35:14,680
Speaker 1: small black hole. The question that comes from Scott. My

726
00:35:14,840 --> 00:35:17,440
Speaker 1: name is Scott and from medical like Washington, and my

727
00:35:17,600 --> 00:35:20,439
Speaker 1: question is if a black hole were to suddenly pop

728
00:35:20,440 --> 00:35:22,920
Speaker 1: into existence about the size of a.

729
00:35:22,800 --> 00:35:24,480
Speaker 2: Pea in the middle of the Earth.

730
00:35:25,120 --> 00:35:27,560
Speaker 1: Would it eat the planet? And if so, about how

731
00:35:27,600 --> 00:35:31,160
Speaker 1: long would it take? Thank you all right? Another tiny question,

732
00:35:31,200 --> 00:35:31,719
Speaker 1: I feel like.

733
00:35:33,800 --> 00:35:36,120
Speaker 2: A cosmic question about tiny things.

734
00:35:35,920 --> 00:35:40,520
Speaker 1: And big destruction. Here is Scott's question is that if

735
00:35:40,560 --> 00:35:44,040
Speaker 1: you suddenly made a pie sized black hole appear in

736
00:35:44,080 --> 00:35:47,279
Speaker 1: the middle of the planet, would it eat up the

737
00:35:47,280 --> 00:35:50,440
Speaker 1: planet and swallow us all into this black hole? Or

738
00:35:50,480 --> 00:35:51,360
Speaker 1: would we survive?

739
00:35:51,760 --> 00:35:53,560
Speaker 2: Yeah? Great question?

740
00:35:53,960 --> 00:35:56,000
Speaker 1: And how long would we be alive if it ends

741
00:35:56,080 --> 00:35:56,840
Speaker 1: up killing us?

742
00:35:57,080 --> 00:35:59,440
Speaker 2: How much time do you have to pack and board

743
00:35:59,440 --> 00:36:00,960
Speaker 2: a ship off the planet? Right?

744
00:36:01,000 --> 00:36:04,200
Speaker 1: How long can you taken that before waking up to

745
00:36:04,360 --> 00:36:09,759
Speaker 1: meet your doom in your toga? Well, Daniel, what's he

746
00:36:09,800 --> 00:36:12,800
Speaker 1: asked for this question? What are some of the basics

747
00:36:12,800 --> 00:36:13,920
Speaker 1: of black holes? We need to know?

748
00:36:14,080 --> 00:36:17,279
Speaker 2: So remember that black holes are like a deformation in

749
00:36:17,360 --> 00:36:20,239
Speaker 2: space and time. They are a place where there's so

750
00:36:20,400 --> 00:36:23,720
Speaker 2: much energy concentrated in a tiny little spot that space

751
00:36:23,760 --> 00:36:26,680
Speaker 2: has curved so much that you formed an event horizon,

752
00:36:27,200 --> 00:36:30,040
Speaker 2: which means nothing can ever escape. An important thing to

753
00:36:30,120 --> 00:36:33,600
Speaker 2: understand is black holes can basically eat anything. You throw

754
00:36:33,640 --> 00:36:37,000
Speaker 2: anything into a black hole, it just adds to its energy.

755
00:36:37,440 --> 00:36:40,279
Speaker 2: You drop into shark, it gets more massive and it

756
00:36:40,280 --> 00:36:43,880
Speaker 2: gets bigger, right exactly, There's a close relationship between the

757
00:36:43,920 --> 00:36:46,239
Speaker 2: mass of the black hole and its radius, and so

758
00:36:46,400 --> 00:36:48,280
Speaker 2: as you add stuff to the black hole, it tends

759
00:36:48,280 --> 00:36:50,680
Speaker 2: to grow. The only exception to this is if you

760
00:36:50,680 --> 00:36:54,160
Speaker 2: had a black hole isolated in space, it would emit

761
00:36:54,239 --> 00:36:58,399
Speaker 2: hawking radiation and gradually disappear. So if you don't feed

762
00:36:58,440 --> 00:37:01,680
Speaker 2: a black hole, it will eventually fade out of existence.

763
00:37:02,080 --> 00:37:04,600
Speaker 2: But any black hole that's near stuff, it's going to

764
00:37:04,640 --> 00:37:07,640
Speaker 2: grab that stuff, pull it in and grow. There's no

765
00:37:07,640 --> 00:37:08,880
Speaker 2: way for the Earth to hang out with like a

766
00:37:08,880 --> 00:37:11,800
Speaker 2: black hole inside of it without that black hole eventually

767
00:37:11,840 --> 00:37:14,600
Speaker 2: eating the planet. So Scott's question number one is like,

768
00:37:14,800 --> 00:37:16,360
Speaker 2: is it going to eat the planet? And the answer

769
00:37:16,560 --> 00:37:18,520
Speaker 2: is yes. So do you have a black hole the

770
00:37:18,520 --> 00:37:21,080
Speaker 2: heart of the planet. That black hole already has a

771
00:37:21,120 --> 00:37:23,520
Speaker 2: lot of gravity. He's talking about a black hole the

772
00:37:23,560 --> 00:37:26,040
Speaker 2: size of a pea. Well, a black hole the size

773
00:37:26,040 --> 00:37:28,280
Speaker 2: of pea doesn't sound very large, like a pea doesn't

774
00:37:28,280 --> 00:37:31,000
Speaker 2: have much gravity, but to make a black hole of

775
00:37:31,040 --> 00:37:34,760
Speaker 2: that size would require about as much mass as the Earth.

776
00:37:35,320 --> 00:37:37,279
Speaker 2: So now you're talking about about as much mass of

777
00:37:37,320 --> 00:37:40,640
Speaker 2: the Earth concentrated down to a pee that's gonna have

778
00:37:40,640 --> 00:37:44,279
Speaker 2: a very strong gravitational effect. Put it anywhere inside the Earth,

779
00:37:44,320 --> 00:37:46,200
Speaker 2: it's going to pull that part of the Earth apart.

780
00:37:46,440 --> 00:37:48,680
Speaker 2: It's going to feed itself on the Earth, and then

781
00:37:48,680 --> 00:37:50,920
Speaker 2: it's going to grow and get more gravity, and you

782
00:37:50,920 --> 00:37:53,880
Speaker 2: have a very rapid runaway effect there where everything eventually

783
00:37:53,920 --> 00:37:56,000
Speaker 2: falls into this new black hole.

784
00:37:56,239 --> 00:37:58,160
Speaker 1: Right, because I guess if you PLoP it in the

785
00:37:58,160 --> 00:38:02,120
Speaker 1: middle of the Earth, it has material to eat right away, right, Like,

786
00:38:02,280 --> 00:38:04,359
Speaker 1: what would happen if you PLoP a p sized black

787
00:38:04,360 --> 00:38:06,719
Speaker 1: hole in the middle space with nothing around it? Would

788
00:38:06,719 --> 00:38:09,319
Speaker 1: it just evaporate or would it stick around for a

789
00:38:09,360 --> 00:38:09,799
Speaker 1: long time?

790
00:38:09,880 --> 00:38:11,680
Speaker 2: Yeah? Absolutely, If you don't feed a black hole, it

791
00:38:11,719 --> 00:38:14,440
Speaker 2: will evaporate. How long it takes to evaporate depends on

792
00:38:14,480 --> 00:38:17,640
Speaker 2: its size, because the Hawking radiation depends on the temperature,

793
00:38:17,640 --> 00:38:20,600
Speaker 2: and the temperature is connected to the size. And actually

794
00:38:20,640 --> 00:38:24,320
Speaker 2: bigger black holes are colder, tend to radiate more slowly,

795
00:38:24,480 --> 00:38:27,280
Speaker 2: So the smaller the black hole, the more the radiation.

796
00:38:27,800 --> 00:38:31,160
Speaker 2: So really big black holes very gently radiate and shrinks

797
00:38:31,280 --> 00:38:34,680
Speaker 2: very slowly. As they get smaller and smaller, they radiate faster.

798
00:38:34,840 --> 00:38:38,040
Speaker 2: And faster till eventually they disappear in quite a bright

799
00:38:38,120 --> 00:38:40,920
Speaker 2: flash of light, which would make evaporating black holes from

800
00:38:40,960 --> 00:38:43,600
Speaker 2: hawking radiation something we might be able to see out

801
00:38:43,640 --> 00:38:46,280
Speaker 2: in the night sky. We've never actually seen one before,

802
00:38:46,440 --> 00:38:49,000
Speaker 2: but people are looking for it. But yeah, you put

803
00:38:49,000 --> 00:38:50,279
Speaker 2: it in the center of the Earth, it's going to

804
00:38:50,320 --> 00:38:50,719
Speaker 2: gobble it.

805
00:38:50,760 --> 00:38:52,799
Speaker 1: Up, right, It's going to start eating the Earth, and

806
00:38:52,840 --> 00:38:55,080
Speaker 1: then it's going to grow. But then I wonder if

807
00:38:55,080 --> 00:38:57,200
Speaker 1: it would eat all of the Earth, Like I wonder

808
00:38:57,239 --> 00:39:00,000
Speaker 1: if at some point we'll eat the inside of the Earth,

809
00:39:00,280 --> 00:39:03,719
Speaker 1: but maybe it'll leave a space between it and the

810
00:39:03,920 --> 00:39:05,040
Speaker 1: outer shell of the Earth.

811
00:39:05,120 --> 00:39:07,799
Speaker 2: Yeah, it actually gets a little bit complicated. What we

812
00:39:07,880 --> 00:39:09,719
Speaker 2: often do in physics is just start with like the

813
00:39:09,719 --> 00:39:12,279
Speaker 2: simplest scenario. Imagine all the mass of the Earth is

814
00:39:12,360 --> 00:39:14,880
Speaker 2: just like a bunch of balls on the surface of

815
00:39:14,880 --> 00:39:17,080
Speaker 2: the Earth and they all fall into the black hole.

816
00:39:17,120 --> 00:39:19,239
Speaker 2: And you can ask, like how long does it take

817
00:39:19,320 --> 00:39:21,840
Speaker 2: all of that mass to fall into the black hole?

818
00:39:22,440 --> 00:39:25,520
Speaker 2: And so that would take about ten ish minutes for

819
00:39:25,600 --> 00:39:27,880
Speaker 2: all the mass of the Earth to fall into this

820
00:39:27,960 --> 00:39:31,319
Speaker 2: central black hole. That's like the fastest it could possibly happen,

821
00:39:31,400 --> 00:39:35,040
Speaker 2: you know, like around ten minutes before everything actually reaches

822
00:39:35,120 --> 00:39:35,839
Speaker 2: the black.

823
00:39:35,520 --> 00:39:37,479
Speaker 1: Hole, Like if it just goes straight in.

824
00:39:37,480 --> 00:39:39,640
Speaker 2: Yeah, if it just goes straight in, And that's the

825
00:39:39,640 --> 00:39:41,040
Speaker 2: most efficient, the fastest way.

826
00:39:41,120 --> 00:39:43,239
Speaker 1: And then you made this calculation, how just by like

827
00:39:43,280 --> 00:39:46,000
Speaker 1: measuring how long a ball on the surface of Earth

828
00:39:46,040 --> 00:39:48,719
Speaker 1: would take to fall into the center of a black

829
00:39:48,760 --> 00:39:49,760
Speaker 1: hole in the middle of Earth.

830
00:39:49,880 --> 00:39:53,799
Speaker 2: Yeah, essentially simple gravity for a simple object, not interacting

831
00:39:53,840 --> 00:39:56,760
Speaker 2: with anything else, And that's the fastest possible thing. Nothing

832
00:39:56,840 --> 00:39:59,759
Speaker 2: is interfering with these objects. But that ignores a lot

833
00:39:59,800 --> 00:40:02,600
Speaker 2: of it important physics, like the Earth is spinning, and

834
00:40:02,640 --> 00:40:05,120
Speaker 2: what would happen if the black hole actually did start

835
00:40:05,120 --> 00:40:07,399
Speaker 2: to eat the center of the Earth is black holes

836
00:40:07,440 --> 00:40:10,960
Speaker 2: have tremendous tidal forces, and those tidal forces would heat

837
00:40:11,080 --> 00:40:14,480
Speaker 2: up the stuff near the black hole. Like surrounding every

838
00:40:14,480 --> 00:40:16,640
Speaker 2: black hole we actually see out there in the universe

839
00:40:16,960 --> 00:40:19,960
Speaker 2: is an accretion disk of stuff that's swirling around it

840
00:40:20,000 --> 00:40:22,839
Speaker 2: and hasn't yet fallen in. So this new black hole

841
00:40:22,840 --> 00:40:25,320
Speaker 2: in the center of the Earth would compress and heat

842
00:40:25,440 --> 00:40:27,279
Speaker 2: up the stuff around the Earth, and it would create

843
00:40:27,320 --> 00:40:30,280
Speaker 2: a lot of radiation which would push stuff out away

844
00:40:30,400 --> 00:40:33,160
Speaker 2: from the black hole. So what we see in reality

845
00:40:33,160 --> 00:40:35,600
Speaker 2: out there in the universe is that there's a maximum

846
00:40:35,680 --> 00:40:38,080
Speaker 2: rate at which black holes can grow because they have

847
00:40:38,160 --> 00:40:40,680
Speaker 2: very strong gravity to pull stuff in, but they also

848
00:40:40,760 --> 00:40:43,719
Speaker 2: tend to create accretion disks, which create radiation to push

849
00:40:43,760 --> 00:40:47,760
Speaker 2: stuff away. So black holes cannot form super duper quickly

850
00:40:47,960 --> 00:40:49,480
Speaker 2: because of this effect.

851
00:40:49,200 --> 00:40:51,440
Speaker 1: Because if things bolt into quickly, then they tend to

852
00:40:51,520 --> 00:40:54,240
Speaker 1: explode as they go in, which would push the stuff

853
00:40:54,239 --> 00:40:56,600
Speaker 1: that's in line to fall in away exactly.

854
00:40:56,640 --> 00:40:59,160
Speaker 2: And stuff is also rotating right, so it doesn't fall

855
00:40:59,200 --> 00:41:02,680
Speaker 2: in immediately. It tends to swirl around the black hole

856
00:41:03,040 --> 00:41:05,239
Speaker 2: before it falls in. It gets heated up, and it

857
00:41:05,360 --> 00:41:08,319
Speaker 2: radiates and it pushes out on other stuff. And so

858
00:41:08,800 --> 00:41:10,840
Speaker 2: while the minimum time for this to happen is like

859
00:41:10,880 --> 00:41:13,399
Speaker 2: ten ish minutes, in reality it would probably take much

860
00:41:13,520 --> 00:41:16,480
Speaker 2: much longer because it would form an accretion disk, and

861
00:41:16,480 --> 00:41:18,359
Speaker 2: it would take a long time for that accretion disc

862
00:41:18,600 --> 00:41:22,239
Speaker 2: to all fall into the black hole. Eventually, it still would, but.

863
00:41:22,160 --> 00:41:24,879
Speaker 1: It would take much much longer, Like how much, Because

864
00:41:25,000 --> 00:41:25,840
Speaker 1: I think that's the question.

865
00:41:26,040 --> 00:41:27,919
Speaker 2: Yeah, I don't have a solid answer for that, because

866
00:41:27,960 --> 00:41:32,480
Speaker 2: that requires calculations that are very complicated and require like

867
00:41:32,640 --> 00:41:37,600
Speaker 2: really intense gravity and multibody simulations. I'd estimate thousands of

868
00:41:37,680 --> 00:41:40,360
Speaker 2: years or maybe even millions of years before the last

869
00:41:40,400 --> 00:41:42,839
Speaker 2: bits of the Earth actually do fall into this new

870
00:41:42,840 --> 00:41:47,240
Speaker 2: black hole, but the Earth would very rapidly be uninhabitable.

871
00:41:47,640 --> 00:41:49,960
Speaker 2: Like this is answering the question of when the last

872
00:41:50,000 --> 00:41:52,720
Speaker 2: tiny bit of earth dust falls into the black hole.

873
00:41:53,040 --> 00:41:55,960
Speaker 2: That might take thousands or millions of years, but still

874
00:41:55,960 --> 00:41:58,040
Speaker 2: you would not want to be on the surface of

875
00:41:58,040 --> 00:42:00,480
Speaker 2: the Earth for more than a few minutes after that

876
00:42:00,520 --> 00:42:02,640
Speaker 2: black hole is created, because it's going to get very

877
00:42:02,680 --> 00:42:04,120
Speaker 2: unpleasant very quickly.

878
00:42:04,040 --> 00:42:06,120
Speaker 1: Like it's going to basically break up the Earth right

879
00:42:06,160 --> 00:42:09,720
Speaker 1: shatter it. Yeah, exactly, they can collapse under its own

880
00:42:09,960 --> 00:42:10,440
Speaker 1: sort of weight.

881
00:42:10,800 --> 00:42:10,920
Speaker 3: Hm.

882
00:42:11,040 --> 00:42:13,640
Speaker 2: Ten minutes is the fastest possible time for the Earth

883
00:42:13,680 --> 00:42:17,520
Speaker 2: to disappear, which tells you that the timescale for effects

884
00:42:17,520 --> 00:42:19,840
Speaker 2: to appear on the surface of the Earth is minutes.

885
00:42:20,239 --> 00:42:22,239
Speaker 2: So the Earth is going to get pulled apart and

886
00:42:22,280 --> 00:42:24,880
Speaker 2: distorted and all sorts of craziness. That's going to happen

887
00:42:24,880 --> 00:42:28,440
Speaker 2: within minutes, even if the complete hoovering up all the

888
00:42:28,520 --> 00:42:30,799
Speaker 2: last bit of the Earth might take much longer because

889
00:42:30,800 --> 00:42:33,240
Speaker 2: of the feedback effect from black hole radiation.

890
00:42:35,320 --> 00:42:38,120
Speaker 1: So all benus you want to get on.

891
00:42:38,080 --> 00:42:40,480
Speaker 2: That spaceship asap. That's the answer.

892
00:42:41,440 --> 00:42:44,200
Speaker 1: Isn't there some science fiction story where they some aliens

893
00:42:44,239 --> 00:42:46,360
Speaker 1: have created a planet with a black hole in the middle,

894
00:42:46,480 --> 00:42:48,320
Speaker 1: like that's powering it or something.

895
00:42:48,440 --> 00:42:50,759
Speaker 2: I haven't read a book like that. In principle, it's

896
00:42:50,800 --> 00:42:54,160
Speaker 2: possible to have a stable structure around a black hole,

897
00:42:54,520 --> 00:42:57,160
Speaker 2: like if it's strong enough and far enough away and

898
00:42:57,239 --> 00:43:00,600
Speaker 2: thin enough to avoid tidal forces, then yeah, you could

899
00:43:00,600 --> 00:43:04,240
Speaker 2: build a big spherical structure kind of like a disin

900
00:43:04,320 --> 00:43:06,040
Speaker 2: sphere around a black.

901
00:43:05,719 --> 00:43:07,920
Speaker 1: Hole and a giant shell, right.

902
00:43:08,000 --> 00:43:10,640
Speaker 2: Yeah, like a giant shell. And if you pour stuff

903
00:43:10,680 --> 00:43:13,400
Speaker 2: into the black hole, you could use the hawking radiation

904
00:43:13,560 --> 00:43:16,600
Speaker 2: from the black hole as an energy source. We even

905
00:43:16,600 --> 00:43:18,840
Speaker 2: talked about using black holes to power a space ship,

906
00:43:19,120 --> 00:43:21,640
Speaker 2: have a whole episode about that. So, yeah, all these

907
00:43:21,680 --> 00:43:24,400
Speaker 2: things are potentially possible, but it depends a lot of

908
00:43:24,440 --> 00:43:26,640
Speaker 2: the details, and you don't build that kind of thing

909
00:43:26,680 --> 00:43:28,560
Speaker 2: by just plopping a black hole at the center of

910
00:43:28,600 --> 00:43:29,640
Speaker 2: an existing planet.

911
00:43:30,719 --> 00:43:34,719
Speaker 1: And it's also unstables that I remember about it, but

912
00:43:34,760 --> 00:43:37,880
Speaker 1: I guess maybe then. An extension of Scott's question is

913
00:43:38,120 --> 00:43:41,600
Speaker 1: what's the smallest black hole we could survive? Or is

914
00:43:41,640 --> 00:43:44,160
Speaker 1: it that any size black hole there is plopped in

915
00:43:44,160 --> 00:43:47,040
Speaker 1: the middle of the Earth would eventually swallow us up.

916
00:43:47,520 --> 00:43:50,120
Speaker 2: Yeah, any size black hole that's plopped in the center

917
00:43:50,160 --> 00:43:52,440
Speaker 2: of the Earth gets bigger, and so there is no

918
00:43:52,600 --> 00:43:55,319
Speaker 2: minimum size we could survive because every black hole just

919
00:43:55,400 --> 00:43:57,000
Speaker 2: grows to be a larger black hole.

920
00:43:57,200 --> 00:43:59,520
Speaker 1: But don't you talk about in the Large Hadron Collider

921
00:44:00,080 --> 00:44:02,080
Speaker 1: make black holes or you might be making black holes,

922
00:44:02,080 --> 00:44:03,880
Speaker 1: but they disappear very quickly.

923
00:44:04,120 --> 00:44:06,799
Speaker 2: Yeah, if you made a super tiny microscopic black hole

924
00:44:07,120 --> 00:44:09,200
Speaker 2: in a vacuum, like we might do with the Large

925
00:44:09,239 --> 00:44:12,760
Speaker 2: Hadron Collider, then it could evaporate too quickly to absorb

926
00:44:12,840 --> 00:44:15,200
Speaker 2: any other material. If you put it in the center

927
00:44:15,239 --> 00:44:17,040
Speaker 2: of the Earth, then you have no chance. Even a

928
00:44:17,080 --> 00:44:20,480
Speaker 2: microscopic black hole will eventually get bigger. But if you

929
00:44:20,480 --> 00:44:23,200
Speaker 2: make a microscopic black hole and a vacuum, it'll evaporate

930
00:44:23,239 --> 00:44:24,680
Speaker 2: before it's dangerous.

931
00:44:24,719 --> 00:44:27,759
Speaker 1: Unless you created knocks on the wall of the Large

932
00:44:27,760 --> 00:44:29,799
Speaker 1: pattern Collider, would that be bad news?

933
00:44:30,120 --> 00:44:32,400
Speaker 2: Black hole we make at the LHC will actually have

934
00:44:32,440 --> 00:44:34,520
Speaker 2: a lot of velocity, so it's not just going to

935
00:44:34,640 --> 00:44:38,160
Speaker 2: stay there inside the LEDC and actually fly off and

936
00:44:38,360 --> 00:44:40,799
Speaker 2: just go through the Earth or into outer space before

937
00:44:40,800 --> 00:44:42,920
Speaker 2: it has a chance to eat anything. They've done all

938
00:44:42,920 --> 00:44:46,080
Speaker 2: these calculations, and they're pretty convinced that it's not dangerous.

939
00:44:46,120 --> 00:44:53,680
Speaker 2: So you know, I mean, fundamentally, we do not understand

940
00:44:53,880 --> 00:44:57,520
Speaker 2: microscopic black holes because it requires a theory of quantum

941
00:44:57,560 --> 00:44:59,600
Speaker 2: gravity to predict what would happen. Because now you're talking

942
00:44:59,640 --> 00:45:03,719
Speaker 2: about gravity of quantum objects, which are uncertain, and so

943
00:45:03,760 --> 00:45:06,160
Speaker 2: it's not something we really know how to calculate. And

944
00:45:06,280 --> 00:45:08,480
Speaker 2: all the calculations done for like black holes with a

945
00:45:08,520 --> 00:45:12,239
Speaker 2: large Hadron collider, they use a semi classical approximation of

946
00:45:12,360 --> 00:45:14,880
Speaker 2: quantum gravity in which nobody really believes.

947
00:45:14,920 --> 00:45:17,839
Speaker 1: Anyway, you're not really making me feel more comfortable.

948
00:45:17,520 --> 00:45:18,879
Speaker 2: Here, Daniel. I wasn't the goal.

949
00:45:19,200 --> 00:45:21,640
Speaker 1: Your assurance is only getting worse.

950
00:45:22,320 --> 00:45:25,160
Speaker 2: I'm telling you we don't really understand super microscopic black

951
00:45:25,160 --> 00:45:26,280
Speaker 2: holes anyway.

952
00:45:26,040 --> 00:45:28,080
Speaker 1: I see, And so therefore we should believe you when

953
00:45:28,160 --> 00:45:29,879
Speaker 1: you say not to worry about it.

954
00:45:30,040 --> 00:45:31,600
Speaker 2: I didn't say not to worry about it. I said

955
00:45:31,600 --> 00:45:33,520
Speaker 2: they've done the calculations, and they tell us not to

956
00:45:33,520 --> 00:45:34,080
Speaker 2: worry about it.

957
00:45:34,239 --> 00:45:36,120
Speaker 1: Uh huh. And now you're telling us.

958
00:45:37,160 --> 00:45:41,799
Speaker 2: I'm saying I'm not worried about it. Oh well, in

959
00:45:41,800 --> 00:45:45,400
Speaker 2: that case, but remember you can always check the website.

960
00:45:45,640 --> 00:45:48,120
Speaker 2: Has the large Hadron collider destroyed the world yet? Dot

961
00:45:48,160 --> 00:45:50,360
Speaker 2: com which we always keep up to date.

962
00:45:50,800 --> 00:45:53,359
Speaker 1: Right, right, although there would be a delay technically right,

963
00:45:53,440 --> 00:45:55,280
Speaker 1: so it could be wrong for about five minutes.

964
00:46:00,200 --> 00:46:01,640
Speaker 2: I don't know about five minutes. I think you'd be

965
00:46:01,719 --> 00:46:02,719
Speaker 2: updated faster than that.

966
00:46:03,160 --> 00:46:05,160
Speaker 1: I hear a lot of nervous laughter here, Daniel.

967
00:46:05,239 --> 00:46:06,960
Speaker 2: If you're destroyed by a black hole and you have

968
00:46:06,960 --> 00:46:09,200
Speaker 2: complains about that website, feel free to email me.

969
00:46:09,360 --> 00:46:10,839
Speaker 1: Yeah, well you get it in time, though.

970
00:46:13,840 --> 00:46:15,719
Speaker 2: I've promised to answer all emails, and so I'm going

971
00:46:15,760 --> 00:46:16,400
Speaker 2: to do my best.

972
00:46:16,760 --> 00:46:19,960
Speaker 1: Yeah, yeah, you might have to break that promise. All right. Well,

973
00:46:19,960 --> 00:46:22,480
Speaker 1: I think that's the answer for sCOD, which is yes,

974
00:46:22,600 --> 00:46:24,919
Speaker 1: if you put a pea sized black hole, which would

975
00:46:24,960 --> 00:46:27,279
Speaker 1: be the equivalent of a black hole with the mass

976
00:46:27,280 --> 00:46:30,120
Speaker 1: of the Earth in the middle of the Earth, next

977
00:46:30,160 --> 00:46:33,000
Speaker 1: to all of the material inside the Earth, then yeah,

978
00:46:33,000 --> 00:46:36,880
Speaker 1: it would quickly grow and swallow us all up, or

979
00:46:36,880 --> 00:46:40,120
Speaker 1: at least destroy the Earth and then eventually swallow our

980
00:46:40,280 --> 00:46:41,080
Speaker 1: remnants up.

981
00:46:41,600 --> 00:46:43,160
Speaker 2: Don't do it, Scott, bad idea.

982
00:46:43,600 --> 00:46:45,320
Speaker 1: Don't do it, Scott, don't do it, Daniel.

983
00:46:47,840 --> 00:46:49,840
Speaker 2: We're not creating pea sized black holes.

984
00:46:49,840 --> 00:46:57,080
Speaker 1: Man, oh right, although you said any size is dangerous,

985
00:46:57,080 --> 00:47:04,759
Speaker 1: so you're not helping me sleep, not my job, all right. Well,

986
00:47:04,840 --> 00:47:08,080
Speaker 1: thanks to everyone who sent in their questions. We always

987
00:47:08,120 --> 00:47:08,719
Speaker 1: appreciate it.

988
00:47:08,960 --> 00:47:12,120
Speaker 2: And thanks everybody who's curious about the universe and shares

989
00:47:12,160 --> 00:47:15,480
Speaker 2: sarah curiosity with us. This whole podcast project is just

990
00:47:15,640 --> 00:47:18,839
Speaker 2: us marinating in the joy of your curiosity. Thanks very

991
00:47:18,920 --> 00:47:19,560
Speaker 2: much everybody.

992
00:47:20,040 --> 00:47:22,960
Speaker 1: You hope you enjoyed that. Thanks for joining us. See

993
00:47:23,000 --> 00:47:23,520
Speaker 1: you next time.

994
00:47:28,160 --> 00:47:31,040
Speaker 2: For more science and curiosity, come find us on social

995
00:47:31,080 --> 00:47:36,040
Speaker 2: media where we answer questions and post videos. We're on Twitter, Discord, Instant,

996
00:47:36,080 --> 00:47:39,800
Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel

997
00:47:39,840 --> 00:47:43,280
Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.

998
00:47:43,560 --> 00:47:48,640
Speaker 2: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

999
00:47:48,840 --> 00:47:51,200
Speaker 2: or wherever you listen to your favorite shows.