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Speaker 1: Hey, Jorgey, how is your commute to work this morning?

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Speaker 2: Pretty short? Taking me about one or two minutes?

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Speaker 1: Is that your typical commune? Do you ever get stuck

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Speaker 1: in traffic and take like a whole five or six minutes?

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Speaker 2: Well, there can be a jam up in the kitchen

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Speaker 2: sometimes usually blueberry jam.

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Speaker 1: Well, I hope your traffic is only caused by the

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Speaker 1: tastiest kinds of accidents, like spilled nutella.

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Speaker 2: Yeah, it's a short community, but it can get kind

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Speaker 2: of nutty.

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Speaker 1: Only the most delicious of delays.

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Speaker 2: Nothing like tasty traffic. I am Horae. I'm the cartoonist

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Speaker 2: and the author of Oliver's Great Big Universe.

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

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Speaker 1: at UC Irvine, and I think think the whole universe

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Speaker 1: is pretty tasty.

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Speaker 2: What does it taste like? Though? Salty? Sweet? Bitter?

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Speaker 1: Astronauts tell us that space smells like barbecue.

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Speaker 2: So it's a umami universe.

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Speaker 1: Exactly. It sounds like it's more savory than sweet.

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Speaker 2: Spacey savory.

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Speaker 1: It's more French fry than milkshake.

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Speaker 2: Got there, I think, or it's French fries with milkshakes.

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Speaker 1: That's what happens in the multiverse when we cross our

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Speaker 1: savory universes with some of the other sweet ones.

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Speaker 2: That's what happens every time I go to McDonald's. Do

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Speaker 2: you ever dip your French fries in milkshake or ice cream?

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Speaker 1: I'm much of a fan of soggy French.

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Speaker 2: Fries, so no, you're missing up. But anyways, welcome to

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Speaker 2: our podcast, Daniel and Jorge Explain the Universe, a production

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Speaker 2: of iHeartRadio.

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Speaker 1: In which we sample all of the flavors of the universe,

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Speaker 1: everything that crunches, everything that crisps, everything that gets soggy

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Speaker 1: when you dip it into a milkshake. We think about

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Speaker 1: the tiniest quantum particles what they are really doing. We

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Speaker 1: think about how fluid flows around you on the surface

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Speaker 1: of the Earth, and we think about the centers of

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Speaker 1: black hole. Our goal is to embrace our curiosity, to

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Speaker 1: think widely about everything out there that makes us wonder,

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Speaker 1: and to talk to you about what we do and

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Speaker 1: don't know about what's happening.

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Speaker 2: That's right. It is a pretty amazing universe. And the

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Speaker 2: universe is everywhere all around you. In fact, even inside

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Speaker 2: of you. The universe is full of amazing facts and

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Speaker 2: questions for us to ask and possibly maybe sometimes answer, like,

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Speaker 2: for example, if you're an alien, do French fries become

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Speaker 2: Earth fries?

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Speaker 1: You know, I'm amazed at our abilities to continually generate

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Speaker 1: new questions that nobody has ever asked before, like that one.

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Speaker 2: Do I get a noble price for asking questions? Or

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Speaker 2: maybe depends on where you're from as an alien, like

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Speaker 2: if you're from Andromeda, do they become Milky Way pries?

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Speaker 1: But you know, sometimes these foods are not well named,

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Speaker 1: like the pastry that in America we call a Danish.

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Speaker 1: The Danish people don't call an American pastry. They actually

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Speaker 1: call it a Vienna pastry.

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Speaker 2: Wait what and what do they call it in Vienna?

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Speaker 2: A US pastry?

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Speaker 1: I think they call it a VNS so they take

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Speaker 1: credit for it. But we named it after the Danish.

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Speaker 2: Well, you know, history goes to the conquerors, I guess.

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Speaker 2: So whoever first discovered the Danish maybe they discovered it

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Speaker 2: in Denmark and then they got to call it the Danish.

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Speaker 1: And I've heard that there's a long debate about the

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Speaker 1: French fry whether it's actually invented in France or in Belgium.

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Speaker 2: But don't they speak French in Belgium, so technically they

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Speaker 2: would still call it pomfrets. So yeah, it's still a

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Speaker 2: French fry.

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Speaker 1: I'm going to stay out of that colonial and political discussion.

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Speaker 2: You know, let's stick to the universe instead, simpler things

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Speaker 2: like everything.

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Speaker 1: If Aliens are mad at us for calling them French fries,

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Speaker 1: at least they're not going to write angry emails to us.

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Speaker 2: Why would they get angry? If anything, it would be

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Speaker 2: the French.

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Speaker 1: I love all the French people and all the Belgian

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Speaker 1: people and all their cuisine and their culture.

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Speaker 2: But not the Danish. The Danish, you want to steal

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Speaker 2: their national pastry away from them.

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Speaker 1: They don't claim it as their national pastry. They call

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Speaker 1: it a Vienna pastry. It's not part of their national pride.

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Speaker 2: What do they called Vienna sausages? Then Danish sausage?

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Speaker 1: You mean wieners in a can. I don't think anybody

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Speaker 1: wants to take credit for that.

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Speaker 2: That's a whole separate universe. But yeah, the universe is

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Speaker 2: full of amazing questions for scientists to ask and also

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Speaker 2: everyday people to ask.

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Speaker 1: These questions we ask about the universe are questions that

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Speaker 1: people have been asking for generations, sometimes for thousands of years.

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Speaker 1: How big is the universe? How does it all work?

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Speaker 1: What's out there waiting for us? Are we alone? Because

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Speaker 1: it's just part of being human to look out of

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Speaker 1: the universe and want to understand it, to generate questions,

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Speaker 1: to have that wonder bubble up inside of you. And

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Speaker 1: it's not just professional scientists and cartoonists who are asking

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Speaker 1: these questions. It's everybody. It's you.

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Speaker 2: Yeah, it does seem to be kind of a human

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Speaker 2: quality curiosity in asking questions about the universe. I mean,

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Speaker 2: you don't see a lot of other animals asking questions

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Speaker 2: or doing research, right, I don't know.

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Speaker 1: I see curiosity in cats and dogs, even rats. There's

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Speaker 1: definitely curiosity out there.

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Speaker 2: You think cats wonder about the origin of the universe,

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Speaker 2: but gravity, the nature of space and time.

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Speaker 1: I think they wonder why their dinner is late. Yeah.

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Speaker 2: Yeah, they're just wondering how to kill you probably if

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Speaker 2: they could.

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Speaker 1: You could call that experimentation, you know.

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Speaker 2: Yeah, murders a feline experimentation FI. But yeah, everybody has questions,

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Speaker 2: and sometimes on this podcast we like to answer them.

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Speaker 1: We love to answer questions. If you are wondering something

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Speaker 1: about the nature of the universe, or there's something that

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Speaker 1: doesn't quite click in your mind. We want to help

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Speaker 1: you make its stap together. So please write to us

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Speaker 1: with your questions to questions at Danielandjorge dot com. When

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Speaker 1: we say it all the time, but we really mean it,

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Speaker 1: we love your questions. We answer all of them, and

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Speaker 1: if there's a question that's especially interesting or I think

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Speaker 1: a lot of people might want to hear the answer to,

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Speaker 1: we will even play it here on the podcast and

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Speaker 1: joke about it.

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Speaker 2: So today on the podcast will be Listener Questions number

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Speaker 2: forty one. Maybe we should stop numbering these question episodes.

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Speaker 2: I feel like at forty one we can probably stop counting,

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Speaker 2: or maybe we should stop with forty two, because that

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Speaker 2: is the answer.

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Speaker 1: That's right and everything. Well. Number them helps me keep

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Speaker 1: track of them, because otherwise I'll get confused about whether

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Speaker 1: or not we already answered a question or not.

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Speaker 2: Oh, I see, so I least itselful for one person, yes, exactly,

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Speaker 2: out of the entire universe.

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Speaker 1: And this way I can refer listeners. I can say,

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Speaker 1: check out Listener Questions twenty four, where we talked about

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Speaker 1: exactly that topic.

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Speaker 2: Oh, I see, they're like issues of a comic book,

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Speaker 2: like ooh, have you heard listener questions number thirty seven?

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Speaker 2: That's the one where the dark Phoenix rises from the ashes.

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Speaker 1: That's the one where we reveal that Jorge is actually Superman.

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Speaker 2: That's right. Do you think maybe these will be collector

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Speaker 2: items someday? Maybe we should make NFTs out of these episodes.

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Speaker 1: I think it's more likely that the aliens come and

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Speaker 1: make French fries out of us.

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Speaker 2: Than somebody would ever want to collect our podcast. Maybe

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Speaker 2: we should record a new French then.

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Speaker 1: But we really do love hearing your questions and thinking

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Speaker 1: about them and answering them. So let me just say again,

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Speaker 1: please don't be shy to write to us questions at

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Speaker 1: Danielandjorge dot com.

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Speaker 2: Yeah, so today we're answering questions from listeners and give

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Speaker 2: them some kind of answer at least, And we have

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Speaker 2: some pretty awesome questions here about the mass of the universe,

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Speaker 2: about gases, about moons made out of gas, and also

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Speaker 2: what would happen if you stuck your finger in a

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Speaker 2: black hole? A physical black hole I imagine.

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Speaker 1: As opposed to what a French fried black hole.

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Speaker 2: I don't know, a metaphorical black hole or something called

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Speaker 2: a black hole, but it's not really a black hole.

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Speaker 1: Mmmm. I see.

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Speaker 2: You just got to be in general careful about what

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Speaker 2: do you mean when you say stick your finger in things?

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Speaker 1: That's true. Some of these questions are a figurative rabbit hole.

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Speaker 2: Yeah, you gotta watch out for those two, because the

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Speaker 2: rabbit might your finger if you stick your finger in it.

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Speaker 2: So let's get to it. Our first question comes from Eric.

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Speaker 3: Hello, Daniel and Jore. I'm a big fan of your podcast.

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Speaker 3: I'm a line hauled truck driver who delivers freight from

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Speaker 3: Utah to Idaho. My question is how many tons of

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Speaker 3: mass would my rig have to pull if I were

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Speaker 3: to drag the whole universe up to Idaho rather than

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Speaker 3: delivering it a few pieces at a time. Please include

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Speaker 3: dark matter in your calculations, though I understand it would

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Speaker 3: be difficult to secure in place. Thank you and keep

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Speaker 3: up the good work.

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Speaker 2: All right, Thank you, Eric. That's an awesome question. And

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Speaker 2: I love that he's a long haul trucker.

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Speaker 1: He's out there delivering those fresh strawberries.

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Speaker 2: Yeah, or do you think he maybe sometimes cargoes frenchies?

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Speaker 1: Is really those long haul truck drivers that make our

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Speaker 1: economy work and keep everybody's shelves stocked. So thanks to

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Speaker 1: all the truckers who keep us fed.

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Speaker 2: Yeah, keep on trucking, and I guess we're happy to

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Speaker 2: keep those truckers entertaining thinking about the universe as they

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Speaker 2: drive those long stretches of road between states.

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Speaker 1: Yeah. One thing makes me worried, though, because a lot

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Speaker 1: of people write in and say that our podcast is

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Speaker 1: very nice to fall asleep to, gives them pleasant dreams

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Speaker 1: or whatever, and I really don't want long haul truckers

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Speaker 1: drifting off while they listen to us joke about the universe.

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Speaker 2: Has anybody ever written to say our podcast helps them

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Speaker 2: stay awake or it rarely happens.

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Speaker 1: I haven't gotten one of those messages yet, but I

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Speaker 1: hope it does that.

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Speaker 2: For Eric. Well, if you're a long haul trucker right

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Speaker 2: now listening to this, wake.

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Speaker 1: Up, don't alarm them, man, keep your.

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Speaker 2: Eyes on the road, that's right, don't look up it's

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Speaker 2: the night sky or at space too much.

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Speaker 1: But Eric asks a really fun question basically about the

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Speaker 1: mass of the whole universe, and I like how he

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Speaker 1: thinks about it in terms of how much his truck

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Speaker 1: can pull.

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Speaker 2: Yeah, it's kind of a funny question. His question is

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Speaker 2: how many tons of mass would his truck have to

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Speaker 2: pull if it had to pull the whole universe from

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Speaker 2: you to to Idaho. I guess that's a very specific.

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Speaker 1: Move they make in Utah. The people in Idaho especially

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Speaker 1: want because it's not potatoes, right. If anything, those are

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Speaker 1: going in the other direction.

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Speaker 2: Sounds like Eric got a request for a quote. Somebody

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Speaker 2: ordered the universe in Idaho.

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Speaker 1: Maybe he brings salt from Salt Lake City to Boise

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Speaker 1: and comes back with potatoes.

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Speaker 2: Right. They ran out of potatoes in Idaho, so they

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Speaker 2: need to import a whole universe of them from Utah.

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Speaker 1: No, dude, it must be the opposite. Idaho is where

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Speaker 1: potatoes grow.

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Speaker 2: That's what I mean. They ran out of potatoes in Iao,

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Speaker 2: so they had to import some from a different universe.

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Speaker 2: I guess.

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Speaker 1: I do think that Utah is a bit of a

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Speaker 1: different universe than Idaho.

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Speaker 4: Oh.

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Speaker 2: I think they're both different universes. Every state is a

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Speaker 2: different universe.

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Speaker 1: They're both beautiful, though, I've been to both. Gorgeous mountains everywhere.

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Speaker 2: But it's an interesting question, I guess. Really he's asking

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Speaker 2: how much does the universe weigh, or how much masses

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Speaker 2: there in the entire universe as far as we know.

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Speaker 1: Yeah, it's a really interesting question, and he thinks about

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Speaker 1: it in terms of his truck. A typical semi can

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Speaker 1: haul about fifteen thousand kilogram of stuff. But the universe,

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Speaker 1: of course, much much bigger than that. And I don't

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Speaker 1: even know how many muches I need to say to

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Speaker 1: give you the sense for how much bigger the universe is.

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Speaker 1: The actual number is that the mass of the part

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Speaker 1: of the universe that we can see is about ten

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Speaker 1: to the fifty three kilograms. So that's ten with fifty

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Speaker 1: three zeros in front of it, whereas his truck can

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Speaker 1: haul fifteen with three zeros in front of it. So

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Speaker 1: it's a lot bigger than what he can pull.

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Speaker 2: Yeah, I think he probably understands that this truck can

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Speaker 2: pull the whole universe. But I think he's asking how

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Speaker 2: much mass would his truck be required to pull if

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Speaker 2: he had to move it from you to Idaho. I

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Speaker 2: think he knows.

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Speaker 1: I'm pretty sure he knows, but the quantity is really staggering.

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Speaker 1: I mean, it's the case where like a kilogram is

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Speaker 1: really the wrong unit. To think about the mass of

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Speaker 1: the universe, a kilogram is like something you could hold

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Speaker 1: in your hand, So ten to the fifty three is

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Speaker 1: just too big a number to think about. If you

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Speaker 1: think about the universe in terms of like loads of

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Speaker 1: Eric's truck, his truck can pull about fifteen thousand kilograms.

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Speaker 1: That still comes out to like ten to forty nine truckloads.

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Speaker 1: So it's still a really really big number.

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Speaker 2: Oh you mean, like if he took the universe broke

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Speaker 2: it down into different pallets, how many trips would we

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Speaker 2: have to make to move the whole universe?

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Speaker 1: Exactly? So moving the whole universe would require moving ten

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Speaker 1: to the fifty three kilograms. Clearly impossible if he did

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Speaker 1: break it down. I know, Eric, you want to do

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Speaker 1: it all in one hall, But if you did break

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Speaker 1: it down into chunks your truck could actually handle, it

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Speaker 1: would take about ten to the forty nine truckloads.

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Speaker 2: And how long does each trip take?

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Speaker 1: So it's about five hours from Salt Lake City to Boise.

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Speaker 1: I'm not sure exactly where he's driving, which makes it

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Speaker 1: like a ten hour round trip. Now if he never sleeps,

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Speaker 1: and that means he has about time for nine hundred

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Speaker 1: trips in a year back and forth, so it's like

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Speaker 1: almost a thousand trips a year. But it's going to

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Speaker 1: take him ten to the forty nine truckloads. That comes

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Speaker 1: out to ten to the forty seven years of driving

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Speaker 1: back and forth, NonStop, no sleeping, no bathroom breaks, to

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Speaker 1: bring the whole universe back and forth between Salt Lakes

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Speaker 1: and Boise.

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Speaker 2: Oh man, but can he listen to our podcast while

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Speaker 2: he's driving? Might make him drive faster. He's like, oh God,

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Speaker 2: this is torture. I just want to get this over with.

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Speaker 2: I have to listen to this podcast.

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Speaker 1: You know, we got like five hundred hours of podcast

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Speaker 1: out there. But even still, he would run out pretty quick.

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Speaker 1: He would have to listen to every episode a lot

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Speaker 1: of times.

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Speaker 2: Interesting. I guess maybe the question is how do we

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Speaker 2: know how much the universe ways? First of all, we

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Speaker 2: don't know if the universe is finite or infinite, right.

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Speaker 1: We certainly don't. The universe could be infinitive, could go

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Speaker 1: on forever, or it could also be finite. The part

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Speaker 1: of the universe that we can see, what we call

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Speaker 1: the observable universe, is just the part where light has

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Speaker 1: had time to get to us from those far reaches

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Speaker 1: beyond that we literally can't see because even though it

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Speaker 1: might exist and photons from it could be racing through

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Speaker 1: space to reach us, it hasn't arrived yet because the

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Speaker 1: universe it's only like fourteen billion years old, so photons

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Speaker 1: that take fifteen billion years to get here haven't arrived. Yets,

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Speaker 1: we haven't seen that part of the universe. So there's

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Speaker 1: like a sphere surrounding us that we call the observable universe,

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Speaker 1: and that's the part we can see, and we can

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Speaker 1: measure how much stuff is in it, and so we

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Speaker 1: can talk about the mass of that part. But that

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Speaker 1: could be literally a zero percent fraction of the infinite universe,

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Speaker 1: or it could be most of the stuff that's out there.

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Speaker 1: We don't know what's beyond the boundary of the observable.

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Speaker 2: Yeah, the universe can be pretty big, but I guess

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Speaker 2: then the question is how do we know how much

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Speaker 2: it weighs or how much mass it has, Like we

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Speaker 2: have a hard time knowing exactly how much mass the

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Speaker 2: Earth has, right, Didn't we have a whole episode about that?

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Speaker 1: Yeah, we did have an episode about measuring the gravitational constant,

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Speaker 1: and that's a fun episode because we talk about how

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Speaker 1: they're trying to make that very very precise. What we

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Speaker 1: do when we measure the universe is that we measure

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Speaker 1: the typical energy density, like how much stuff is there

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Speaker 1: in a cubic light year of space an average cubic

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Speaker 1: light year of space. So we go out there and

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Speaker 1: we look at like all the stars and the gas

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Speaker 1: and the dust, and we add up all the dark

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Speaker 1: matter as Eric suggested that we include, and we measured

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Speaker 1: that by looking at how like galaxy swirl and the

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Speaker 1: large scale structure the universe which is influenced by dark matter.

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Speaker 1: We also add of the energy of the expansion dark energy.

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Speaker 1: So there's all these different components of the sort of

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Speaker 1: energy budget of the universe. Some of them we can

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Speaker 1: measure independently, some of them we measure together. All of

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Speaker 1: them we have multiple different ways of measuring. So we're

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Speaker 1: pretty confident we know all those various pieces of the pie.

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Speaker 2: But I think Eric is asking about the mass of

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Speaker 2: the universe, not the energy of it, right, because like

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Speaker 2: energy doesn't necessarily have to haul if we have to

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Speaker 2: move it from Utah to Idaho.

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Speaker 1: Yeah, that's right. There's different components is matter. There's radiation,

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Speaker 1: there's dark energy, so just the matter part of it, right,

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Speaker 1: we can measure that as well. Just the matter part

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Speaker 1: we can measure separately. And we've done that.

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Speaker 2: How do we do that? Like, how do we even

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Speaker 2: know how much the Earth weighs? Sorry? Giant scale? We

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Speaker 2: can put the whole earth on.

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Speaker 1: Well, once we measure the gravitational constant, which required using

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Speaker 1: like a pendulum and a weird mountain in Scotland that

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Speaker 1: we knew the density of, then we could measure the

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Speaker 1: mass of the Earth by understanding how it moves or

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Speaker 1: on the Sun. Because once you have the gravitational constant,

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Speaker 1: do you know the force?

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Speaker 2: But when do we need to know? Also the mass

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Speaker 2: of the Sun and how do we know that?

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Speaker 1: So the mass in general of stars we can connect

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Speaker 1: to their brightness because there's a model that tells us

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Speaker 1: that brighter stars are heavier, and that's somewhat theoretical but

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Speaker 1: also pretty well established. So in general we can tell

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Speaker 1: the mass of stars by looking at how bright they are.

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Speaker 2: Interesting, but it's based on a theory sort of, right.

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Speaker 1: Yeah, it is based on a theory. We have this

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Speaker 1: theory of how stars form, how they operate, how the

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Speaker 1: mass of those stars determines their temperature, which it determines

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Speaker 1: how bright they are. It has to do with how

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Speaker 1: fusion happens at various temperatures, and that works pretty well.

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Speaker 1: Of course, there's still big unanswered questions about what's going

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Speaker 1: on at the heart of star, the plasma flux tubes

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Speaker 1: that are snapping in the magnetic fields that don't really

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Speaker 1: make any sense. But on the whole, we're pretty confident

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Speaker 1: in our understanding of how massive stars are. Sometimes we

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Speaker 1: get lucky we see like a binary star system, and

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Speaker 1: we can use that to calibrate this because by the

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Speaker 1: relative motion we understand their masses.

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Speaker 2: M okay, stars that they're What about like planets and

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Speaker 2: gas and dost like? Have we measured the mass of

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Speaker 2: planets around other stars or do we just sort of

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Speaker 2: ignore that it's in say it's negligible.

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Speaker 1: That really is negligible, Like even in our Solar system,

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Speaker 1: the mass of things that are not the Sun is

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Speaker 1: about one percent. We can measure the mass of some

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Speaker 1: planets around other stars because we can see their size

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Speaker 1: as they eclipse their star, and we can get their

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Speaker 1: mass from the period, and so that tells us their

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Speaker 1: density et cetera. Et cetera. So we can study a

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Speaker 1: few planets outside our solar system, but on the whole

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Speaker 1: we have not observed very many of them. But mostly

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Speaker 1: it's stars. And then there's gas and dust. A huge

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Speaker 1: fraction of the mass of the universe that's not dark matter,

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Speaker 1: just the normal mass, is in gas and dust. A

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Speaker 1: lot of that is in galaxies, but also a lot

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Speaker 1: of that is between galaxies, Like the gas that flows

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Speaker 1: between galaxies that's still falling into galaxies is a huge

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Speaker 1: fraction of the normal matter in the universe.

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Speaker 2: And then how do you measure that. I mean, it's

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Speaker 2: so far away and it doesn't shine like a star.

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Speaker 2: Do you know how much of that stuff is out there?

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Speaker 1: That's pretty difficult to measure because it's diffuse. One way

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Speaker 1: we can do it is by looking at quasars. Quasars

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Speaker 1: send out these bright rays of light, these like pencil

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Speaker 1: beams of light, and when they pass through these filaments,

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Speaker 1: they get distorted, or they get diffracted, or they get bent.

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Speaker 1: So in some cases we have these beams that penetrate

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Speaker 1: this cosmic web and give us a measurement for what's there,

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Speaker 1: though it can be pretty tricky and those are pretty

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Speaker 1: rare so again we have models that describe like the

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Speaker 1: overall evolution of the universe, like the large scale structure

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Speaker 1: of the universe that tell us roughly how much gas

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Speaker 1: there is, but a lot of it has not been

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Speaker 1: directly seen. We actually had a fun episode about how

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Speaker 1: slime molds teach us about the large scale structure of

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Speaker 1: the universe and where these cosmic filaments are because they

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Speaker 1: tend to form in patterns that are similar to that

406
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Speaker 1: cosmic structure, but a lot of it is not observed.

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Speaker 1: It's extrapolated from a few observations.

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Speaker 2: So then you extrapolate that to hold galaxies, Like how

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Speaker 2: do you know how much mass is in a galaxy?

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Speaker 2: You only see di ferent far away.

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Speaker 1: We can measure the mass of a galaxy by looking

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Speaker 1: at the brightness of the stars, which tells us the

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Speaker 1: mass of the stars, then also watching its spin, which

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Speaker 1: tells us how much invisible mass there is. Because most

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Speaker 1: of the mass of most galaxies is actually in dark matter,

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Speaker 1: like eighty to ninety percent, and that we can't see

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Speaker 1: directly in any way. We can only see its gravitational

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Speaker 1: effects on the rest of the galaxy. So galaxies that

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Speaker 1: are spinning really really fast The only way to understand

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Speaker 1: why they are held together, why they're not throwing their

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Speaker 1: stars into intergalactic space, is to imagine that they have

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Speaker 1: a lot of dark matter in them. Sometimes we can

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Speaker 1: also see that dark matter directly through gravitational lensing, as

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Speaker 1: it distorts the light from other background galaxies.

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Speaker 2: I'm sort of getting the idea that you don't know

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Speaker 2: how much the universe wasays. A lot of it seems

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Speaker 2: sort of based on theories and models and what we

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Speaker 2: think is out there, but it sort of doesn't feel

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Speaker 2: like you've gone out there and measured how much mass

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Speaker 2: there is.

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Speaker 1: There's definitely a lot of extrapolation. And you know, something

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Speaker 1: that's happened recently is that cosmology has become a precision science.

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Speaker 1: It used to be the cosmologist people who think about

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Speaker 1: like the whole universe only really cared about getting answers

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Speaker 1: correct within like a factor of two or factor of five.

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Speaker 1: You know, that was precision cosmology a few decades ago.

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Speaker 1: These days, things have gotten better, and now we can

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Speaker 1: measure these things down to like five percent, one percent,

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Speaker 1: a tenth of one percent, and we're being more and

440
00:20:18,080 --> 00:20:21,320
Speaker 1: more careful about those uncertainties, asking questions like you're asking, like,

441
00:20:21,359 --> 00:20:23,560
Speaker 1: how do we really know them? Could we be getting

442
00:20:23,560 --> 00:20:25,720
Speaker 1: this wrong and in what ways? And do we have

443
00:20:25,760 --> 00:20:29,280
Speaker 1: another way to test this independently? So cosmology has really

444
00:20:29,280 --> 00:20:31,679
Speaker 1: become more and more precise, and you're certainly right that

445
00:20:31,720 --> 00:20:34,159
Speaker 1: we don't know exactly how much mass there is in

446
00:20:34,200 --> 00:20:36,680
Speaker 1: the universe. We have a pretty good picture to within,

447
00:20:36,760 --> 00:20:37,920
Speaker 1: you know, like one percent.

448
00:20:38,720 --> 00:20:40,600
Speaker 2: I guess even if you're off by you know, a

449
00:20:40,640 --> 00:20:43,480
Speaker 2: factor of ten or even one hundred, it's still a lot,

450
00:20:43,640 --> 00:20:45,720
Speaker 2: Like it would be the difference between ten to the

451
00:20:45,720 --> 00:20:48,639
Speaker 2: forty nine truckloads or ten to the forty eight truckloads,

452
00:20:48,640 --> 00:20:50,639
Speaker 2: which is still a lot of truckloads. Which is a

453
00:20:50,640 --> 00:20:51,720
Speaker 2: truckload of truckloads.

454
00:20:51,720 --> 00:20:54,399
Speaker 1: It's still a lot of truckloads. Yeah, exactly. And we

455
00:20:54,520 --> 00:20:56,879
Speaker 1: try to be careful about what we don't know, but

456
00:20:56,920 --> 00:20:59,480
Speaker 1: there's always room for surprises, right. The history of physics

457
00:20:59,520 --> 00:21:01,800
Speaker 1: is filled with examples of times when we thought we

458
00:21:01,880 --> 00:21:03,200
Speaker 1: knew what we were doing and then it was all

459
00:21:03,240 --> 00:21:06,640
Speaker 1: blown up because we discovered something which shakes the foundations.

460
00:21:07,000 --> 00:21:09,359
Speaker 1: So we could certainly be wrong about it, but I'd

461
00:21:09,359 --> 00:21:10,200
Speaker 1: be surprised, all.

462
00:21:10,240 --> 00:21:12,800
Speaker 2: Right, Well, I think that's the answer for Eric. He

463
00:21:12,840 --> 00:21:14,679
Speaker 2: asked how many tons of mass would his truck have

464
00:21:14,800 --> 00:21:17,119
Speaker 2: to pull if he were to move it from Utah

465
00:21:17,200 --> 00:21:20,760
Speaker 2: to Idaho, and the answer is about approximately We think

466
00:21:20,960 --> 00:21:24,720
Speaker 2: ten to the fifty three kilograms, which is a truckload

467
00:21:24,760 --> 00:21:25,520
Speaker 2: of truckloads.

468
00:21:26,880 --> 00:21:28,200
Speaker 1: Better get some coffee.

469
00:21:27,880 --> 00:21:30,879
Speaker 2: Eric, and maybe put this podcast on repeat unless it

470
00:21:30,880 --> 00:21:33,359
Speaker 2: makes you fall asleep, in which case maybe not. All right,

471
00:21:33,440 --> 00:21:36,280
Speaker 2: let's get to our other questions here. There's one about

472
00:21:37,040 --> 00:21:39,880
Speaker 2: moons made out of gas, and also what would happen

473
00:21:39,920 --> 00:21:42,480
Speaker 2: if you stuck your finger in a black hole? So

474
00:21:42,560 --> 00:21:45,000
Speaker 2: we'll get to those, but first let's take a quick break.

475
00:21:57,760 --> 00:21:58,040
Speaker 5: All right.

476
00:21:58,080 --> 00:22:01,119
Speaker 2: We're answering questions from listeners. We just asked her a

477
00:22:01,160 --> 00:22:04,200
Speaker 2: great one about the mass of the entire universe, or

478
00:22:04,200 --> 00:22:07,680
Speaker 2: at least the observable universe. And our next question comes

479
00:22:07,720 --> 00:22:09,800
Speaker 2: from Tim from Virginia.

480
00:22:09,840 --> 00:22:13,479
Speaker 4: Hey, Daniel and Jorge. This is Tim from Virginia. I

481
00:22:13,600 --> 00:22:19,159
Speaker 4: was thinking recently about gas, giant planets, and moons and was.

482
00:22:19,200 --> 00:22:21,600
Speaker 2: Curious why all of the moons that I've.

483
00:22:21,440 --> 00:22:24,200
Speaker 4: Ever heard of are rocky and there are no gas

484
00:22:24,200 --> 00:22:25,840
Speaker 4: moons that exist?

485
00:22:26,280 --> 00:22:26,800
Speaker 1: Or do they?

486
00:22:27,840 --> 00:22:32,080
Speaker 2: Why and why not? Thanks for answering, cheers, Why and

487
00:22:32,119 --> 00:22:36,480
Speaker 2: why not? That's the fundamental human question. But Dad, this

488
00:22:36,560 --> 00:22:38,680
Speaker 2: is a great question from Tim. Thank you Tim. And

489
00:22:38,720 --> 00:22:41,760
Speaker 2: his question is are there moons out there, at least

490
00:22:41,800 --> 00:22:44,360
Speaker 2: in our Solar system that are made out of gas?

491
00:22:44,560 --> 00:22:47,520
Speaker 1: Yeah? A really find question because he's noticing that there's

492
00:22:47,720 --> 00:22:50,919
Speaker 1: like two different kinds of planets, rocky planets where you

493
00:22:50,920 --> 00:22:53,800
Speaker 1: can walk around on the surface, and then like gas

494
00:22:53,840 --> 00:22:57,240
Speaker 1: giants like Jupiter and Saturn that are being blobs mostly

495
00:22:57,280 --> 00:22:59,560
Speaker 1: of gas that you just like gently sink into if

496
00:22:59,560 --> 00:23:01,639
Speaker 1: you try to walk on. All the moons, of course,

497
00:23:01,800 --> 00:23:03,760
Speaker 1: seem to be rocky, and so it's a great question.

498
00:23:04,040 --> 00:23:05,879
Speaker 1: Are the moons made of gas? And why not?

499
00:23:06,200 --> 00:23:08,159
Speaker 2: Yeah? And why skip from solid to gas? Could there

500
00:23:08,200 --> 00:23:09,440
Speaker 2: be liquid moons out there?

501
00:23:12,320 --> 00:23:14,160
Speaker 1: Are you? Especially if they'sty today? You want to drink

502
00:23:14,160 --> 00:23:16,359
Speaker 1: a whole moon, you know, to put your straw up

503
00:23:16,400 --> 00:23:17,000
Speaker 1: to it and just.

504
00:23:16,880 --> 00:23:20,880
Speaker 2: Like shop Yeah inhil a moon, eat the moon, drink

505
00:23:20,920 --> 00:23:23,640
Speaker 2: a moon worm or menu options for moons.

506
00:23:24,000 --> 00:23:26,879
Speaker 1: I want a moon boba, right, just like floating tapioca

507
00:23:26,880 --> 00:23:28,560
Speaker 1: inside the moon with a huge straw.

508
00:23:28,640 --> 00:23:30,200
Speaker 2: Yeah, Like is it going to hit your eye like

509
00:23:30,240 --> 00:23:33,040
Speaker 2: a big pizza pie or you know, is it going

510
00:23:33,080 --> 00:23:35,960
Speaker 2: to hit your face like a big puffer air.

511
00:23:36,080 --> 00:23:37,800
Speaker 1: And I like this question because it makes us think

512
00:23:37,840 --> 00:23:40,800
Speaker 1: about like why we have gas giants in the first place,

513
00:23:40,840 --> 00:23:43,040
Speaker 1: Like how do you get a gas planet to form?

514
00:23:43,119 --> 00:23:45,520
Speaker 2: Anyway, I guess it's sort of like that's how things

515
00:23:45,680 --> 00:23:47,760
Speaker 2: forman space, Like if you have a big cloud of

516
00:23:47,960 --> 00:23:50,960
Speaker 2: gas out there, it's eventually going to collapse into a

517
00:23:51,000 --> 00:23:52,760
Speaker 2: gas body, right.

518
00:23:52,640 --> 00:23:56,480
Speaker 1: Yeah, And most of the universe are these lighter elements hydrogen, helium,

519
00:23:56,520 --> 00:23:59,199
Speaker 1: et cetera, which we think of as gases, and so

520
00:23:59,240 --> 00:24:02,639
Speaker 1: the Sun is mostly made of hydrogen, and Jupiter is

521
00:24:02,680 --> 00:24:06,119
Speaker 1: mostly made of hydrogen. Hydrogen dominates the whole universe, and

522
00:24:06,119 --> 00:24:08,879
Speaker 1: so of course it also dominates the Solar System. The

523
00:24:08,920 --> 00:24:12,240
Speaker 1: other fun stuff that make us up carbon and oxygen

524
00:24:12,320 --> 00:24:15,040
Speaker 1: and nitrogen. It's a tiny fraction of the universe and

525
00:24:15,119 --> 00:24:17,760
Speaker 1: also a tiny fraction of the Solar System.

526
00:24:17,880 --> 00:24:20,199
Speaker 2: Like the most of the regular mass of the universe

527
00:24:20,359 --> 00:24:22,520
Speaker 2: is what percent of hydrogen.

528
00:24:22,200 --> 00:24:25,480
Speaker 1: So hydrogen is like ninety one percent of the universe

529
00:24:25,560 --> 00:24:28,400
Speaker 1: by atoms, like if you count the number of atoms,

530
00:24:28,560 --> 00:24:31,359
Speaker 1: but it's only like seventy four percent of the mass

531
00:24:31,400 --> 00:24:34,320
Speaker 1: fraction of the universe because it's so light. So uranium,

532
00:24:34,359 --> 00:24:37,560
Speaker 1: for example, is many many times heavier than hydrogen. So

533
00:24:37,640 --> 00:24:41,600
Speaker 1: a single uranium atom outweighs hundreds of hydrogen atoms.

534
00:24:41,800 --> 00:24:44,320
Speaker 2: But there aren't that many uranium atoms in the universe.

535
00:24:44,560 --> 00:24:47,439
Speaker 1: No, there really are not very many uranium atoms, so

536
00:24:47,480 --> 00:24:50,040
Speaker 1: like ninety one percent of all atoms out there are

537
00:24:50,160 --> 00:24:50,760
Speaker 1: just hydrogen.

538
00:24:50,880 --> 00:24:53,400
Speaker 2: Yeah, so it's sort of a hydrogen universe. But then

539
00:24:53,400 --> 00:24:55,480
Speaker 2: I guess the question is can you form a moon

540
00:24:55,520 --> 00:24:57,560
Speaker 2: out of hydrogen or any gas?

541
00:24:57,680 --> 00:24:59,280
Speaker 1: Yeah, So I think to answer that question we have

542
00:24:59,320 --> 00:25:01,960
Speaker 1: to think about why we have also planets made out

543
00:25:02,000 --> 00:25:04,840
Speaker 1: of gas and some planets made out of rocks, right,

544
00:25:04,920 --> 00:25:07,040
Speaker 1: Like why do we have rocky planets and why do

545
00:25:07,080 --> 00:25:09,880
Speaker 1: we have gas planets? And as you said, everything forms

546
00:25:09,960 --> 00:25:12,720
Speaker 1: out of the original blob that created the Solar System,

547
00:25:12,840 --> 00:25:15,919
Speaker 1: a blob of gas and dust, etc. That then collapsed

548
00:25:15,960 --> 00:25:18,200
Speaker 1: and made the star. Not all of it falls into

549
00:25:18,240 --> 00:25:20,360
Speaker 1: the star, because some of it's spinning really really fast

550
00:25:20,440 --> 00:25:22,679
Speaker 1: and ends up in orbit, and some of that stuff

551
00:25:22,720 --> 00:25:25,679
Speaker 1: has enough gravity of its own to gather itself together

552
00:25:26,000 --> 00:25:29,399
Speaker 1: to make planets. And there's this division between the inner

553
00:25:29,400 --> 00:25:32,280
Speaker 1: Solar System and the outer Solar System. The inner Solar

554
00:25:32,320 --> 00:25:34,359
Speaker 1: System is where we get like rocky planets, and the

555
00:25:34,400 --> 00:25:37,160
Speaker 1: outer Solar system is where we get like gas giants,

556
00:25:37,440 --> 00:25:41,000
Speaker 1: and the division comes from where water is able to freeze.

557
00:25:41,200 --> 00:25:43,720
Speaker 1: Like in the inner Solar System, there's so much radiation

558
00:25:43,840 --> 00:25:46,560
Speaker 1: from the Sun that water is basically a vapor even

559
00:25:46,560 --> 00:25:49,040
Speaker 1: when it's out in space, but outpast what we call

560
00:25:49,119 --> 00:25:51,600
Speaker 1: the snow line, and you're far enough away from the Sun,

561
00:25:52,080 --> 00:25:55,520
Speaker 1: water can form crystals. So those crystals gather together and

562
00:25:55,520 --> 00:25:57,920
Speaker 1: they help build those planets. So as the Solar System

563
00:25:58,000 --> 00:26:01,240
Speaker 1: is forming, those water crystals help see the formation of

564
00:26:01,280 --> 00:26:03,879
Speaker 1: the gas giants, help them gobble up their own helping

565
00:26:03,920 --> 00:26:07,480
Speaker 1: of gas, which is why Jupiter got such a big scoop.

566
00:26:07,200 --> 00:26:10,040
Speaker 2: Of hydrogen, right, Isn't it also a little bit because

567
00:26:10,119 --> 00:26:12,480
Speaker 2: like any gas that was close to the Sun sort

568
00:26:12,480 --> 00:26:14,720
Speaker 2: of fill in right away because it's so light.

569
00:26:14,880 --> 00:26:17,960
Speaker 1: Yeah, there's actually two different effects there. One is you're right,

570
00:26:18,000 --> 00:26:20,680
Speaker 1: the Sun gobbles up a lot of gas and dust,

571
00:26:20,800 --> 00:26:23,760
Speaker 1: and then once it starts fusing, it blows away all

572
00:26:23,840 --> 00:26:26,879
Speaker 1: remaining gas and dust, like the solar wind blew away

573
00:26:26,960 --> 00:26:29,879
Speaker 1: the Earth's atmosphere in the early formation of the Solar system.

574
00:26:30,119 --> 00:26:32,640
Speaker 1: So any hydrogen in the inner Solar System either fell

575
00:26:32,680 --> 00:26:35,840
Speaker 1: into the Sun or got blown out by the Sun's radiation,

576
00:26:36,359 --> 00:26:38,359
Speaker 1: which is why we end up with only the heavier

577
00:26:38,400 --> 00:26:41,399
Speaker 1: stuff making planets in the Inner Solar System and in

578
00:26:41,440 --> 00:26:43,760
Speaker 1: the Outer Solar System, you're far enough away from the

579
00:26:43,760 --> 00:26:46,159
Speaker 1: Sun that you can capture some hydrogen and you have

580
00:26:46,240 --> 00:26:49,960
Speaker 1: the assistance of these water crystals to seed your gravitational attraction.

581
00:26:50,400 --> 00:26:52,760
Speaker 1: Plus you're far enough away from the Sun that its

582
00:26:52,840 --> 00:26:56,080
Speaker 1: radiation doesn't blow all of your hydrogen out into deep space.

583
00:26:56,160 --> 00:26:58,000
Speaker 2: All right, So there was sort of a big band

584
00:26:58,080 --> 00:27:01,000
Speaker 2: of hydrogen gas in the Outer Solar System, which is

585
00:27:01,000 --> 00:27:03,800
Speaker 2: where you know Jupiter and Saturn and all of those

586
00:27:03,920 --> 00:27:06,399
Speaker 2: gas planets came from. But I guess the question is

587
00:27:06,440 --> 00:27:07,720
Speaker 2: can you make a moon out of gas?

588
00:27:07,760 --> 00:27:10,160
Speaker 1: So in principle, you can make a moon out of gas,

589
00:27:10,200 --> 00:27:12,879
Speaker 1: but you probably can't keep a moon out of gas

590
00:27:13,280 --> 00:27:15,679
Speaker 1: because in order to hold onto gas, you have to

591
00:27:15,760 --> 00:27:19,440
Speaker 1: have enough mass, Like the Earth holds onto its thin

592
00:27:19,560 --> 00:27:22,879
Speaker 1: layer of atmosphere because of its mass. The gravity of

593
00:27:22,920 --> 00:27:26,080
Speaker 1: the Earth is holding the atmosphere to it. Mars, which

594
00:27:26,119 --> 00:27:29,960
Speaker 1: is smaller, has much less mass than a much thinner atmosphere.

595
00:27:30,240 --> 00:27:33,720
Speaker 1: Our moon, which is even smaller than Mars, has much

596
00:27:33,840 --> 00:27:37,760
Speaker 1: much less gravity and has essentially no atmosphere for that reason.

597
00:27:37,880 --> 00:27:39,879
Speaker 1: So you make something that's too small, even if it

598
00:27:40,000 --> 00:27:42,480
Speaker 1: started out with a little envelope of gas, or even

599
00:27:42,520 --> 00:27:44,760
Speaker 1: a lot of gas, it's just gonna lose it. It's

600
00:27:44,800 --> 00:27:46,199
Speaker 1: just gonna boil away into space.

601
00:27:47,040 --> 00:27:49,680
Speaker 2: I guess if you're like a gas molecule and you're

602
00:27:49,680 --> 00:27:52,240
Speaker 2: hanging out in the Moon, you could be like, oh,

603
00:27:52,280 --> 00:27:54,520
Speaker 2: this moon is not so attractive. I'll just fly off

604
00:27:54,560 --> 00:27:57,119
Speaker 2: into space. That's what you mean by boil off, right.

605
00:27:57,080 --> 00:28:00,000
Speaker 1: Yeah, every hydrogen molecule in the vicinity of the moon

606
00:28:00,119 --> 00:28:03,280
Speaker 1: and basically has escape velocity. It's not that hard to

607
00:28:03,440 --> 00:28:05,719
Speaker 1: escape the gravity of the Moon because the Moon doesn't

608
00:28:05,720 --> 00:28:09,000
Speaker 1: have that much mass. So any hydrogen atom that's out

609
00:28:09,040 --> 00:28:11,520
Speaker 1: there is basically hot enough it has enough speed that

610
00:28:11,600 --> 00:28:13,760
Speaker 1: if it's pointed in the direction of space, it'll just

611
00:28:13,840 --> 00:28:16,480
Speaker 1: keep going and the Moon can't hold onto it. That's

612
00:28:16,520 --> 00:28:19,000
Speaker 1: also partially true for the Earth, like the Earth is

613
00:28:19,080 --> 00:28:21,960
Speaker 1: losing some of its hydrogen. That's one reason why hydrogen

614
00:28:22,040 --> 00:28:25,320
Speaker 1: is a tiny fraction of our atmosphere, because it's the

615
00:28:25,359 --> 00:28:27,520
Speaker 1: hardest to hold onto because it's so light.

616
00:28:28,560 --> 00:28:31,280
Speaker 2: So now let's say what happens if I made a

617
00:28:31,320 --> 00:28:33,040
Speaker 2: moon out of gas. Like I just took a tag

618
00:28:33,119 --> 00:28:36,119
Speaker 2: of hydrogen out into space and I released it, creating

619
00:28:36,160 --> 00:28:39,080
Speaker 2: a cloud of hydrogen. Is that cloud gonna keep orbiting

620
00:28:39,080 --> 00:28:41,000
Speaker 2: around the Earth or is it just gonna disperse?

621
00:28:41,120 --> 00:28:43,680
Speaker 1: It depends a little bit also on the temperature. If

622
00:28:43,680 --> 00:28:46,959
Speaker 1: you could chill that hydrogen down and keep it cold,

623
00:28:47,120 --> 00:28:49,160
Speaker 1: then it might stay together. If it was kind of more,

624
00:28:49,200 --> 00:28:50,840
Speaker 1: if you like sprayed it out of a nozzle and

625
00:28:50,880 --> 00:28:53,480
Speaker 1: it's moving pretty fast, then it's just gonna disperse.

626
00:28:54,200 --> 00:28:55,880
Speaker 2: It be liquid. Do you mean, like if it was

627
00:28:55,960 --> 00:28:58,960
Speaker 2: super cold it would be liquid or would it stay

628
00:28:58,960 --> 00:28:59,600
Speaker 2: in gas form?

629
00:29:00,080 --> 00:29:02,640
Speaker 1: Sure? It is essentially zero out there, so the phases

630
00:29:02,680 --> 00:29:04,600
Speaker 1: get a little bit weird you think about it in

631
00:29:04,640 --> 00:29:09,000
Speaker 1: terms of vapor versus crystals. Really there's no like flowing liquid.

632
00:29:09,440 --> 00:29:11,560
Speaker 2: All right, So then could you form any moon out

633
00:29:11,560 --> 00:29:12,000
Speaker 2: of gas?

634
00:29:12,040 --> 00:29:14,280
Speaker 1: If possible, if you made it really really cold and

635
00:29:14,360 --> 00:29:18,000
Speaker 1: really really massive, but then basically you're making another planet.

636
00:29:18,200 --> 00:29:20,160
Speaker 1: That's basically what the gas giants are.

637
00:29:20,960 --> 00:29:22,920
Speaker 2: So like, for example, if I take the mass of

638
00:29:22,960 --> 00:29:26,160
Speaker 2: our moon and made it into gas, would it stay

639
00:29:26,200 --> 00:29:29,360
Speaker 2: as a you know, as a satellite or would that

640
00:29:29,520 --> 00:29:30,120
Speaker 2: just disperse?

641
00:29:30,360 --> 00:29:32,920
Speaker 1: It would just disperse? Yeah, there are some moons in

642
00:29:32,960 --> 00:29:35,960
Speaker 1: the Solar System that do have an atmosphere like Titan.

643
00:29:35,960 --> 00:29:38,840
Speaker 1: For example, a moon of Saturn does have an atmosphere,

644
00:29:38,840 --> 00:29:41,200
Speaker 1: and its atmosphere is actually a little bit thicker than

645
00:29:41,240 --> 00:29:44,120
Speaker 1: the Earth's atmosphere. Titan, of course, it's not a small moon.

646
00:29:44,160 --> 00:29:46,560
Speaker 1: It's a really massive thing. It's like ten times the

647
00:29:46,600 --> 00:29:47,480
Speaker 1: mass of our moon.

648
00:29:48,480 --> 00:29:51,360
Speaker 2: I think you're saying that there aren't any then gas

649
00:29:51,400 --> 00:29:52,600
Speaker 2: moons in our solar system.

650
00:29:52,640 --> 00:29:54,880
Speaker 1: There aren't any gas moons in our solar system. And

651
00:29:54,960 --> 00:29:57,400
Speaker 1: almost every moon in our solar system doesn't even have

652
00:29:57,440 --> 00:29:59,720
Speaker 1: an atmosphere because they don't have the mass to hold

653
00:29:59,720 --> 00:30:02,479
Speaker 1: it toge together. Titan is really an exception. It's the

654
00:30:02,520 --> 00:30:05,120
Speaker 1: only one that has enough mass to hold an atmosphere.

655
00:30:05,160 --> 00:30:07,280
Speaker 1: That's probably because it's really cold, and also because it's

656
00:30:07,280 --> 00:30:10,680
Speaker 1: around Saturn instead of Jupiter. Jupiter has more radiation to

657
00:30:10,760 --> 00:30:14,200
Speaker 1: blast its moons than Saturn does. If you took a huge,

658
00:30:14,200 --> 00:30:16,640
Speaker 1: massive blob of gas and made it really, really cold,

659
00:30:16,680 --> 00:30:18,960
Speaker 1: it might collapse into a gas moon, but it would

660
00:30:18,960 --> 00:30:20,920
Speaker 1: take very special conditions.

661
00:30:20,440 --> 00:30:23,560
Speaker 2: All right. It sounds like gas is just too slippery

662
00:30:23,600 --> 00:30:26,360
Speaker 2: to wispy to really kind of hold together unless you

663
00:30:26,360 --> 00:30:28,720
Speaker 2: have a lot of gravity, in which case you would

664
00:30:28,760 --> 00:30:31,440
Speaker 2: be a gas planet like Jupiter or Saturn.

665
00:30:31,560 --> 00:30:33,560
Speaker 1: Yeah, though, as we talked about recently on the podcast,

666
00:30:33,600 --> 00:30:35,719
Speaker 1: the distinction between a moon and a planet is a

667
00:30:35,720 --> 00:30:37,960
Speaker 1: little bit fuzzy. You might have, for example, a pair

668
00:30:38,000 --> 00:30:41,320
Speaker 1: of planets that are orbiting each other, call one a planet,

669
00:30:41,400 --> 00:30:44,440
Speaker 1: one a moon. In that scenario, both of them could

670
00:30:44,440 --> 00:30:47,520
Speaker 1: really be gas planets. The one of them, technically you

671
00:30:47,600 --> 00:30:49,640
Speaker 1: might call a moon of the other one and make

672
00:30:49,720 --> 00:30:51,440
Speaker 1: the thing big enough to be able to hold its gas.

673
00:30:51,480 --> 00:30:52,960
Speaker 1: It's basically a planet.

674
00:30:53,240 --> 00:30:55,800
Speaker 2: Like you could have a situation where like a Saturn

675
00:30:55,920 --> 00:30:58,760
Speaker 2: Neptune is orbiting around a Jupiter out there in another

676
00:30:58,760 --> 00:31:01,800
Speaker 2: solar system, in which case you would have a gas moon.

677
00:31:01,920 --> 00:31:04,320
Speaker 1: Yeah, although it might be like a binary planet system

678
00:31:04,400 --> 00:31:06,520
Speaker 1: sharing an orbit. But yeah, then it's just a question

679
00:31:06,600 --> 00:31:07,080
Speaker 1: of names.

680
00:31:07,360 --> 00:31:10,640
Speaker 2: I wonder if, technically, like our atmosphere sort of is

681
00:31:10,720 --> 00:31:15,520
Speaker 2: like a gas moon, right, I mean, technically all the

682
00:31:16,360 --> 00:31:19,600
Speaker 2: gas in our atmosphere is kind of in orbit around

683
00:31:19,680 --> 00:31:22,200
Speaker 2: the Earth, right, It's not stuck to the Earth technically.

684
00:31:22,440 --> 00:31:24,560
Speaker 1: That's an interesting question. And we did talk in that

685
00:31:24,680 --> 00:31:27,960
Speaker 1: episode about moons that there's no lower limit to the

686
00:31:27,960 --> 00:31:31,160
Speaker 1: definition of moon. It's basically any natural satellite. If you

687
00:31:31,200 --> 00:31:35,120
Speaker 1: go far out past the atmosphere to Earth's exosphere, you

688
00:31:35,120 --> 00:31:38,000
Speaker 1: have these little particles which really are in orbit around

689
00:31:38,040 --> 00:31:40,000
Speaker 1: the Earth. In the atmosphere, it's not really fair to

690
00:31:40,000 --> 00:31:42,040
Speaker 1: say it's in orbit because a lot of the forces

691
00:31:42,040 --> 00:31:44,960
Speaker 1: on those objects come from neighboring gas molecules. Out in

692
00:31:44,960 --> 00:31:48,040
Speaker 1: the exosphere where it's really collisionless, where the molecules don't

693
00:31:48,080 --> 00:31:50,080
Speaker 1: really talk to each other. Then yeah, you could say

694
00:31:50,080 --> 00:31:52,000
Speaker 1: those things are in orbit around the Earth. So each

695
00:31:52,000 --> 00:31:53,760
Speaker 1: one is like a particle sized moon.

696
00:31:55,320 --> 00:31:57,720
Speaker 2: There you go. I guess you can have a gas moon,

697
00:31:57,800 --> 00:32:00,600
Speaker 2: but you can have a gas sort of moon or

698
00:32:00,680 --> 00:32:01,680
Speaker 2: orbit around the planet.

699
00:32:02,680 --> 00:32:04,840
Speaker 1: Yeah, you can't have a gas giant moon, but you

700
00:32:04,840 --> 00:32:06,840
Speaker 1: can have a gas particle moon, I suppose.

701
00:32:07,840 --> 00:32:10,680
Speaker 2: All right, Well, I think that answers Tim's question. Are

702
00:32:10,680 --> 00:32:12,959
Speaker 2: there moons made out of gas? Not that we know of,

703
00:32:13,160 --> 00:32:15,560
Speaker 2: at least not here in our Solar system. There might

704
00:32:15,600 --> 00:32:18,200
Speaker 2: be out there binary planet systems that are made out

705
00:32:18,200 --> 00:32:19,720
Speaker 2: of gas, in which case you might call one of

706
00:32:19,760 --> 00:32:23,160
Speaker 2: them a gas moon. But also maybe there are particle

707
00:32:23,600 --> 00:32:25,760
Speaker 2: moons going around the Earth right now. They're just too

708
00:32:25,760 --> 00:32:27,920
Speaker 2: small to see, all right, let's get to our last

709
00:32:27,960 --> 00:32:31,440
Speaker 2: question from Stuart about what happens when you stick your

710
00:32:31,440 --> 00:32:34,240
Speaker 2: finger in a black hole. So we'll get to that,

711
00:32:34,320 --> 00:32:49,560
Speaker 2: but first stick another quick break. All right, we're answering

712
00:32:49,560 --> 00:32:52,440
Speaker 2: listener questions, and we've answered questions about the mass of

713
00:32:52,480 --> 00:32:55,080
Speaker 2: the universe and about whether moons can be made out

714
00:32:55,120 --> 00:32:58,440
Speaker 2: of gas. Our last question comes from Stewart from New Zealand.

715
00:32:58,520 --> 00:33:01,600
Speaker 5: Hey, Danieline hei here grew up in South Africa but

716
00:33:01,720 --> 00:33:04,120
Speaker 5: live in Auckland, New Zealan. Now big fan of the show,

717
00:33:04,160 --> 00:33:06,440
Speaker 5: been listening since the very beginning. I've got a bit

718
00:33:06,440 --> 00:33:09,200
Speaker 5: of a hypothetical that's been making my brain herd. I

719
00:33:09,320 --> 00:33:12,120
Speaker 5: was wondering, what if we could create a stable black hole,

720
00:33:12,160 --> 00:33:14,160
Speaker 5: say roughly earth mass, which I know is going to

721
00:33:14,160 --> 00:33:15,959
Speaker 5: be about the size of a ping pong ball, or

722
00:33:16,160 --> 00:33:17,920
Speaker 5: maybe a bit larger to say the size of a

723
00:33:17,960 --> 00:33:20,280
Speaker 5: tennis ball, but critically small enough that it's not going

724
00:33:20,360 --> 00:33:22,520
Speaker 5: to suck us in. And I then wondered what would

725
00:33:22,520 --> 00:33:24,880
Speaker 5: happen if I stuck my fingertip in and pulled my

726
00:33:24,920 --> 00:33:27,760
Speaker 5: finger out again. I presume my fingertip would get ripped off.

727
00:33:27,800 --> 00:33:30,520
Speaker 5: But then I was wondering about what forignification effects might

728
00:33:30,520 --> 00:33:34,160
Speaker 5: occur on my actual finger, and then also made me

729
00:33:34,200 --> 00:33:36,840
Speaker 5: wonder would I then see an image of my fingertip

730
00:33:37,560 --> 00:33:40,000
Speaker 5: on the surface of the black hole. And then also

731
00:33:40,160 --> 00:33:42,000
Speaker 5: if I was to come back, say a week later,

732
00:33:42,120 --> 00:33:44,120
Speaker 5: would I still see that image of my finger on

733
00:33:44,160 --> 00:33:46,120
Speaker 5: the black hole. I'm hoping you can help me out

734
00:33:46,120 --> 00:33:48,000
Speaker 5: with the answers, because this one's really been making my

735
00:33:48,040 --> 00:33:50,840
Speaker 5: brain herd love the show before to the next episode.

736
00:33:50,880 --> 00:33:51,400
Speaker 1: Thanks guys.

737
00:33:51,560 --> 00:33:55,320
Speaker 2: Awesome question or should I see? Questions from Stewart, one

738
00:33:55,360 --> 00:33:58,440
Speaker 2: of our og listeners from NZ New Zealand. It sounds

739
00:33:58,480 --> 00:34:00,080
Speaker 2: like he basically just wants to pull a prank the

740
00:34:00,120 --> 00:34:02,760
Speaker 2: black hole and be like, hey, black hole, pull my finger.

741
00:34:02,880 --> 00:34:05,000
Speaker 1: It sounds like he's really curious and if we put

742
00:34:05,000 --> 00:34:06,680
Speaker 1: a black hole in front of him, he would not

743
00:34:06,760 --> 00:34:09,080
Speaker 1: be able to resist sticking something inside.

744
00:34:10,680 --> 00:34:12,040
Speaker 2: Well, I'm glad he's going to do it, because I

745
00:34:12,040 --> 00:34:15,040
Speaker 2: definitely don't want to try with my finger. So that's

746
00:34:15,040 --> 00:34:17,279
Speaker 2: an interesting question. I guess he really just kind of

747
00:34:17,440 --> 00:34:20,239
Speaker 2: wants to know what happens to things as they go

748
00:34:20,360 --> 00:34:23,080
Speaker 2: into a black hole, you know, because it's so weird

749
00:34:23,120 --> 00:34:25,600
Speaker 2: to think about what happens in the vicinity of a

750
00:34:25,600 --> 00:34:28,000
Speaker 2: black hole. And I guess he's painting the scenario where

751
00:34:28,040 --> 00:34:30,840
Speaker 2: we somehow create a black hole with the same mass

752
00:34:30,840 --> 00:34:33,440
Speaker 2: as the Earth, which would be I think about the

753
00:34:33,480 --> 00:34:36,520
Speaker 2: size of a pigpunk ball or a small lemon, right,

754
00:34:36,640 --> 00:34:38,000
Speaker 2: And like, what if you had it right in front

755
00:34:38,040 --> 00:34:39,600
Speaker 2: of you, what did you stuck your finger in it?

756
00:34:39,920 --> 00:34:40,600
Speaker 2: What would happen?

757
00:34:40,760 --> 00:34:43,200
Speaker 1: Yeah? I love this question because it makes it immediate. Right,

758
00:34:43,239 --> 00:34:46,560
Speaker 1: black holes seem weird and mysterious and out in deep space.

759
00:34:46,760 --> 00:34:48,960
Speaker 1: That makes you want to like explore it concretely, like

760
00:34:49,040 --> 00:34:50,680
Speaker 1: have one in front of you and poke it and

761
00:34:50,719 --> 00:34:53,200
Speaker 1: prod it. And you know, that's what physics labs are

762
00:34:53,239 --> 00:34:55,160
Speaker 1: all about, and that's why we are trying to make

763
00:34:55,200 --> 00:34:58,000
Speaker 1: black holes the large Hatreron Collider so we can do

764
00:34:58,160 --> 00:35:01,840
Speaker 1: these kinds of experiments I mean with Stuart's fingertips. But yeah,

765
00:35:02,080 --> 00:35:03,560
Speaker 1: we want to play with black holes.

766
00:35:03,680 --> 00:35:07,000
Speaker 2: It sounds like you're playing with everybody's fingers by making

767
00:35:07,040 --> 00:35:10,000
Speaker 2: black holes here on Earth? Have you asked everyone's permission

768
00:35:10,040 --> 00:35:12,120
Speaker 2: to pull their fingers? But yeah, I guess it's an

769
00:35:12,120 --> 00:35:14,879
Speaker 2: interesting scenario because you know, we are used to thinking

770
00:35:14,920 --> 00:35:17,040
Speaker 2: about black holes as being humongous, right, I mean the

771
00:35:17,040 --> 00:35:19,440
Speaker 2: one at the center of our galaxy is many millions

772
00:35:19,440 --> 00:35:23,399
Speaker 2: of times bigger than our sun or heavier than our sun,

773
00:35:23,440 --> 00:35:25,200
Speaker 2: And so you imagine that if you're right next to

774
00:35:25,200 --> 00:35:27,680
Speaker 2: a black hole, it just looks like a gigantic thing

775
00:35:27,719 --> 00:35:31,160
Speaker 2: that covers your entire field of vision. But maybe if

776
00:35:31,160 --> 00:35:34,360
Speaker 2: it's small, like about the size of a lemon or

777
00:35:34,400 --> 00:35:36,680
Speaker 2: a penguin ball, maybe it'd be small enough to like

778
00:35:36,880 --> 00:35:38,840
Speaker 2: do little experiments on it, like stick your finger in it.

779
00:35:38,920 --> 00:35:41,640
Speaker 1: Yeah, you're right. The black holes are not about enormous

780
00:35:41,680 --> 00:35:44,920
Speaker 1: amounts of mass. They're really about the density of mass.

781
00:35:45,360 --> 00:35:47,719
Speaker 1: So you could take almost anything and if you squeeze

782
00:35:47,719 --> 00:35:51,440
Speaker 1: it down enough into a small enough radius, high enough density,

783
00:35:52,040 --> 00:35:54,680
Speaker 1: then you'll form an event horizon. The calculation is called

784
00:35:54,719 --> 00:35:57,120
Speaker 1: the short Stiles radius. It tells you the radius of

785
00:35:57,160 --> 00:36:00,160
Speaker 1: the event horizon for a given mass, so's long as

786
00:36:00,160 --> 00:36:03,160
Speaker 1: you get all the mass of something within that radius,

787
00:36:03,239 --> 00:36:05,920
Speaker 1: then it becomes a black hole. You get an event horizon.

788
00:36:06,000 --> 00:36:07,920
Speaker 1: And if you plug the numbers in for the Earth,

789
00:36:08,320 --> 00:36:10,960
Speaker 1: then the radius of that event horizon is just under

790
00:36:11,040 --> 00:36:13,400
Speaker 1: one centimeter. So if you were able to take the

791
00:36:13,440 --> 00:36:16,880
Speaker 1: Earth and somehow squeeze it down to something with the

792
00:36:16,960 --> 00:36:19,680
Speaker 1: radius of a centimeter, it would have an event horizon.

793
00:36:19,760 --> 00:36:21,759
Speaker 1: All that mass inside of it would have so much

794
00:36:21,840 --> 00:36:25,200
Speaker 1: gravity that it would bend space and create that threshold.

795
00:36:25,400 --> 00:36:27,200
Speaker 2: So if you could do that, you would have a

796
00:36:27,239 --> 00:36:30,080
Speaker 2: black hole possibly in front of you, right like on

797
00:36:30,120 --> 00:36:30,720
Speaker 2: your desktop.

798
00:36:30,920 --> 00:36:32,319
Speaker 1: You would have a black hole in front of you.

799
00:36:32,520 --> 00:36:35,120
Speaker 1: Though it would be very, very powerful. There's a couple

800
00:36:35,200 --> 00:36:38,200
Speaker 1: confusing things going on here. On one hand, Stewart's on

801
00:36:38,200 --> 00:36:39,799
Speaker 1: the right track that if you can pack the Earth

802
00:36:39,840 --> 00:36:42,440
Speaker 1: into a black hole, you're not fundamentally changing the amount

803
00:36:42,480 --> 00:36:44,799
Speaker 1: of mass that's there. You're just squeezing it down. So

804
00:36:44,840 --> 00:36:47,520
Speaker 1: if you stay at the same distance you were before,

805
00:36:47,960 --> 00:36:49,960
Speaker 1: you're still going to feel the same amount of gravity.

806
00:36:49,960 --> 00:36:52,160
Speaker 1: He's imagining that an earth mass black hole is not

807
00:36:52,239 --> 00:36:55,080
Speaker 1: going to be that powerful because the Earth's gravity doesn't

808
00:36:55,080 --> 00:36:57,320
Speaker 1: feel that powerful. I mean, I'm standing on the Earth's

809
00:36:57,320 --> 00:36:59,560
Speaker 1: surface that can jump and avoid it, right, But that's

810
00:36:59,560 --> 00:37:02,520
Speaker 1: because I'm pretty far away from the center of mass

811
00:37:02,600 --> 00:37:05,480
Speaker 1: of the Earth. If I formed an earth mass black

812
00:37:05,520 --> 00:37:08,040
Speaker 1: hole and then got really really close to it, like

813
00:37:08,080 --> 00:37:11,600
Speaker 1: a centimeter, two centimeters, even a meter, its gravity would

814
00:37:11,640 --> 00:37:14,279
Speaker 1: be much more powerful than the gravity we feel here

815
00:37:14,320 --> 00:37:16,440
Speaker 1: on the surface of the Earth. Because I'd be much

816
00:37:16,520 --> 00:37:17,320
Speaker 1: much closer.

817
00:37:17,520 --> 00:37:19,400
Speaker 2: Right, Like, if I made a black hole like that,

818
00:37:19,400 --> 00:37:20,920
Speaker 2: I would the same mass as to Earth, and i

819
00:37:21,000 --> 00:37:23,439
Speaker 2: put it in the center of the Earth, and I'm

820
00:37:23,520 --> 00:37:26,799
Speaker 2: standing about an earth radius away from it, i would

821
00:37:26,800 --> 00:37:29,160
Speaker 2: feel the same gravity that I'm feeling right now, which

822
00:37:29,200 --> 00:37:31,120
Speaker 2: is doesn't seem like a lot. But I'm pretty far

823
00:37:31,160 --> 00:37:35,200
Speaker 2: away from the black hole, right It's like ten thousand

824
00:37:35,400 --> 00:37:36,440
Speaker 2: miles or something like that.

825
00:37:36,560 --> 00:37:38,680
Speaker 1: You're pretty far from the center of mass of the Earth.

826
00:37:38,920 --> 00:37:42,520
Speaker 1: If instead you compacted all that mass into one centimeter

827
00:37:42,640 --> 00:37:44,919
Speaker 1: and then you stood right next to it, then you'd

828
00:37:44,920 --> 00:37:48,480
Speaker 1: be seven hundred million times closer to the center of

829
00:37:48,520 --> 00:37:50,440
Speaker 1: mass than you are in the surface of the Earth.

830
00:37:51,080 --> 00:37:55,040
Speaker 1: And because gravity gets stronger with distance squared, like twice

831
00:37:55,080 --> 00:37:58,759
Speaker 1: as close means four times as strong, then the gravity

832
00:37:58,960 --> 00:38:01,920
Speaker 1: of the earth mass black hole, if you're one centimeter

833
00:38:02,040 --> 00:38:05,360
Speaker 1: away from it, would be quadrillions of times more powerful

834
00:38:05,360 --> 00:38:06,280
Speaker 1: than Earth's gravity.

835
00:38:06,560 --> 00:38:08,360
Speaker 2: Right, it would be like five times ten to the

836
00:38:08,560 --> 00:38:12,640
Speaker 2: seventeen right five with seventeen zeros basically.

837
00:38:12,440 --> 00:38:16,560
Speaker 1: G exactly, so it would gobble Steward up. There wouldn't

838
00:38:16,600 --> 00:38:18,560
Speaker 1: be like time to think about which finger to stick

839
00:38:18,600 --> 00:38:22,000
Speaker 1: into it. It's to be incredibly powerful gravity you would

840
00:38:22,000 --> 00:38:23,040
Speaker 1: slurp him up in a moment.

841
00:38:23,160 --> 00:38:24,680
Speaker 2: Yeah, I think you're saying, if you're close enough to

842
00:38:24,680 --> 00:38:27,120
Speaker 2: touch it, that means you're at arm's length from it, Yes,

843
00:38:27,239 --> 00:38:30,040
Speaker 2: in which case the gravity would be super duper strong,

844
00:38:30,120 --> 00:38:33,640
Speaker 2: but maybe more important, the tidle forces would be shredding

845
00:38:33,719 --> 00:38:35,560
Speaker 2: you apart exactly.

846
00:38:35,800 --> 00:38:39,520
Speaker 1: The title forces come from the variation of gravity across distance.

847
00:38:40,000 --> 00:38:42,200
Speaker 1: If you're a point mass, you don't feel any title forces.

848
00:38:42,239 --> 00:38:45,080
Speaker 1: You just feel gravity. But if you're larger, so that

849
00:38:45,160 --> 00:38:47,000
Speaker 1: parts of you are closer to the black hole and

850
00:38:47,040 --> 00:38:49,360
Speaker 1: parts of you are further away, then they're feeling different

851
00:38:49,440 --> 00:38:52,600
Speaker 1: amounts of gravity. And basically the black hole is tugging

852
00:38:52,640 --> 00:38:54,799
Speaker 1: you apart because it's pulling on different parts of you

853
00:38:55,160 --> 00:38:56,320
Speaker 1: with different strengths.

854
00:38:56,560 --> 00:38:58,719
Speaker 2: Right, Like that happens right now as you're sitting there

855
00:38:58,800 --> 00:39:00,759
Speaker 2: or standing there on the surface, so the Earth your

856
00:39:00,800 --> 00:39:03,239
Speaker 2: feet are getting pulled more than your head.

857
00:39:03,440 --> 00:39:05,120
Speaker 1: Yeah, your feet are getting pulled more than your head.

858
00:39:05,160 --> 00:39:07,799
Speaker 1: So your Earth is trying to pull your head off

859
00:39:07,840 --> 00:39:10,440
Speaker 1: of your body. And as you get closer to the

860
00:39:10,480 --> 00:39:13,400
Speaker 1: black hole, the difference in those two forces grows, and

861
00:39:13,440 --> 00:39:16,200
Speaker 1: so the effective force the Earth trying to decapitate. You

862
00:39:16,560 --> 00:39:20,759
Speaker 1: also grows, and eventually it overcomes your body's ability to

863
00:39:20,840 --> 00:39:22,520
Speaker 1: keep your head on your shoulders.

864
00:39:22,600 --> 00:39:24,360
Speaker 2: So like, if you were maybe a meter from a

865
00:39:24,400 --> 00:39:26,960
Speaker 2: small black hole like that and you raise your arm

866
00:39:27,120 --> 00:39:30,120
Speaker 2: to point your finger towards it, your finger would suddenly

867
00:39:30,120 --> 00:39:32,640
Speaker 2: feel a huge amount more force than the rest of

868
00:39:32,640 --> 00:39:35,879
Speaker 2: your body. So basically it would pull your finger, right,

869
00:39:35,880 --> 00:39:38,800
Speaker 2: it will shred pull your finger out of your body.

870
00:39:38,920 --> 00:39:41,759
Speaker 1: Yeah, you can calculate the safe distance with which you

871
00:39:41,800 --> 00:39:44,480
Speaker 1: can approach a black hole, and it depends on the

872
00:39:44,520 --> 00:39:46,799
Speaker 1: mass of the black hole, of course, because the tile

873
00:39:46,840 --> 00:39:49,680
Speaker 1: forces go by like the derivative of the gravitational force,

874
00:39:50,280 --> 00:39:53,040
Speaker 1: and for an earth mass black hole, it's between one

875
00:39:53,200 --> 00:39:56,600
Speaker 1: and ten thousand kilometers. So you can't get very close

876
00:39:56,640 --> 00:39:59,520
Speaker 1: to an earth mass black hole without its charading you apart.

877
00:40:00,000 --> 00:40:02,960
Speaker 2: Oh, so you'd have to be pretty much as far

878
00:40:03,160 --> 00:40:05,239
Speaker 2: away from it as we are from the center of

879
00:40:05,239 --> 00:40:06,279
Speaker 2: the Earth right now, For.

880
00:40:06,280 --> 00:40:08,680
Speaker 1: An earth mass black hole, you need to still stay

881
00:40:08,880 --> 00:40:11,840
Speaker 1: at least a thousand kilometers away from the edge of

882
00:40:11,880 --> 00:40:14,000
Speaker 1: the black hole to avoid being pulled apart.

883
00:40:14,239 --> 00:40:17,920
Speaker 2: So basically you can't stick your finger inside of that black.

884
00:40:17,719 --> 00:40:21,239
Speaker 1: Hole and less your thanos and you have like more

885
00:40:21,280 --> 00:40:25,400
Speaker 1: body integrity and ability to resist the tidal forces somehow.

886
00:40:25,520 --> 00:40:27,560
Speaker 1: Then yeah, you can never even get close enough to

887
00:40:27,600 --> 00:40:28,360
Speaker 1: stick your finger in.

888
00:40:28,440 --> 00:40:30,520
Speaker 2: Well, I guess you could. I mean you'd raise your hand,

889
00:40:31,400 --> 00:40:35,439
Speaker 2: the bung hole will rip your arm out, your finger out,

890
00:40:35,520 --> 00:40:38,600
Speaker 2: and then technically it would get sucked in and you'd

891
00:40:38,600 --> 00:40:40,840
Speaker 2: be sort of sticking your finger in, but you wouldn't

892
00:40:40,880 --> 00:40:42,240
Speaker 2: be attached to that finger.

893
00:40:42,400 --> 00:40:44,480
Speaker 1: Yeah, and your finger would be a long string of

894
00:40:44,480 --> 00:40:47,719
Speaker 1: particles pulled into spaghetti by the tidal forces before it

895
00:40:47,760 --> 00:40:48,879
Speaker 1: even got to the black hole.

896
00:40:49,000 --> 00:40:51,600
Speaker 2: But I think maybe Stuart's question was, like, you know,

897
00:40:51,719 --> 00:40:54,040
Speaker 2: let's say that you made a black hole, maybe with

898
00:40:54,160 --> 00:40:57,480
Speaker 2: smaller or maybe you're somehow able to create a stick

899
00:40:57,920 --> 00:41:00,200
Speaker 2: that is strong enough to hold together that you can

900
00:41:00,239 --> 00:41:03,040
Speaker 2: poke into a black hole. I think he's asking what

901
00:41:03,040 --> 00:41:05,319
Speaker 2: would you see? What would happen? Because I know we've

902
00:41:05,360 --> 00:41:10,040
Speaker 2: talked about like around a black hole, time freezes to stop. Right.

903
00:41:10,120 --> 00:41:13,520
Speaker 1: Yeah, when space gets curved, it time goes slow. So

904
00:41:13,719 --> 00:41:17,040
Speaker 1: things that fall into a black hole for an outside observer,

905
00:41:17,480 --> 00:41:20,320
Speaker 1: their time goes slower. So if you drop a clock

906
00:41:20,440 --> 00:41:22,400
Speaker 1: into a black hole and then you watch it with

907
00:41:22,480 --> 00:41:24,880
Speaker 1: a telescope, you'll see that the time on that clock

908
00:41:24,880 --> 00:41:27,600
Speaker 1: will tick slower than the clock that you are holding.

909
00:41:27,840 --> 00:41:30,640
Speaker 1: That also controls how quickly it falls into a black hole.

910
00:41:31,120 --> 00:41:33,959
Speaker 1: So as things approach the event horizon, their time gets

911
00:41:33,960 --> 00:41:37,400
Speaker 1: slower and slower, and they get more and more smeared out. Also,

912
00:41:37,480 --> 00:41:40,919
Speaker 1: they get red shifted by that curvature, so things get

913
00:41:41,000 --> 00:41:44,160
Speaker 1: slowed down and smeared out into the red pininy.

914
00:41:44,280 --> 00:41:46,319
Speaker 2: I guess if you take this stick that you're going

915
00:41:46,360 --> 00:41:48,800
Speaker 2: to stick into the black hole, you put an indestructible

916
00:41:48,960 --> 00:41:51,439
Speaker 2: watch at the end of it, and then you use

917
00:41:51,480 --> 00:41:54,440
Speaker 2: that to poke the black hole, you would see it.

918
00:41:54,760 --> 00:41:56,640
Speaker 2: I guess you would see it approach the black hole

919
00:41:56,680 --> 00:41:59,400
Speaker 2: the event horizon. You would see that the takes in

920
00:41:59,440 --> 00:42:02,959
Speaker 2: the clocks aren't going slower, taking slower. And then would

921
00:42:02,960 --> 00:42:07,520
Speaker 2: you actually see that the rod the event horizon if

922
00:42:07,560 --> 00:42:08,759
Speaker 2: you keep pushing it towards it.

923
00:42:08,840 --> 00:42:10,720
Speaker 1: So this is a little bit tricky and a common

924
00:42:10,760 --> 00:42:13,600
Speaker 1: source of misunderstanding. People often say you can never see

925
00:42:13,640 --> 00:42:16,640
Speaker 1: anything enter a black hole because time slows down and

926
00:42:16,640 --> 00:42:18,200
Speaker 1: you have to wait till the end of the universe

927
00:42:18,239 --> 00:42:21,440
Speaker 1: to see something actually fall into the black hole. That's true.

928
00:42:21,520 --> 00:42:23,799
Speaker 1: If you just drop like a particle into a black hole,

929
00:42:23,760 --> 00:42:26,080
Speaker 1: it'll take forever for it to actually fall in. But

930
00:42:26,160 --> 00:42:28,719
Speaker 1: what's happening as it falls in is that the event

931
00:42:28,760 --> 00:42:32,439
Speaker 1: horizon is already growing, like as it approaches the black hole,

932
00:42:32,520 --> 00:42:35,840
Speaker 1: it contributes its gravitational energy to the mass of the

933
00:42:35,880 --> 00:42:38,680
Speaker 1: black hole. So the event horizon is actually growing out

934
00:42:38,719 --> 00:42:40,560
Speaker 1: to meet it. It's not like it has to pass

935
00:42:40,600 --> 00:42:43,120
Speaker 1: over the event horizon to contribute to the black hole.

936
00:42:43,440 --> 00:42:46,000
Speaker 1: The two approach each other very slowly. What that means

937
00:42:46,160 --> 00:42:48,440
Speaker 1: is if you then throw something else in, like a

938
00:42:48,480 --> 00:42:51,920
Speaker 1: second particle, that second particle will pull the event horizon

939
00:42:51,960 --> 00:42:54,840
Speaker 1: out even further and you will see the first one absorbed.

940
00:42:54,920 --> 00:42:56,880
Speaker 1: So it's true that if you drop a single particle

941
00:42:56,920 --> 00:42:59,680
Speaker 1: and then nothing else into a black hole, it will

942
00:42:59,719 --> 00:43:02,080
Speaker 1: never enter the event horizon. But if you use a stick,

943
00:43:02,120 --> 00:43:04,360
Speaker 1: which is like a long string of particles, then the

944
00:43:04,400 --> 00:43:06,799
Speaker 1: next particle pulls the event horizon over the previous one,

945
00:43:06,840 --> 00:43:09,200
Speaker 1: et cetera, et cetera, so you actually would see the

946
00:43:09,239 --> 00:43:10,560
Speaker 1: tip enter the black hole.

947
00:43:10,719 --> 00:43:12,800
Speaker 2: All right, well, maybe let's do it play by place.

948
00:43:12,840 --> 00:43:15,160
Speaker 2: I have this long indestructible stick with a watch at

949
00:43:15,200 --> 00:43:17,439
Speaker 2: the end of it. I pointed towards the black hole.

950
00:43:17,520 --> 00:43:20,400
Speaker 2: I poke the black hole, and I stop at the

951
00:43:20,480 --> 00:43:23,120
Speaker 2: moment the tip touches the black hole. It's at the

952
00:43:23,239 --> 00:43:24,960
Speaker 2: edge of the black hole, and I push it in

953
00:43:25,080 --> 00:43:27,759
Speaker 2: an inch. Are you saying that that that inch of

954
00:43:27,920 --> 00:43:32,399
Speaker 2: indestructible rod that I push it into this black hole

955
00:43:32,560 --> 00:43:36,080
Speaker 2: is enough to grow the event horizon an inch?

956
00:43:36,480 --> 00:43:38,879
Speaker 1: The mount of the event horizon grows depends on the

957
00:43:38,920 --> 00:43:40,840
Speaker 1: mass of the thing that you're putting into it, So

958
00:43:40,880 --> 00:43:42,759
Speaker 1: it depends if this rod is made out of like

959
00:43:42,920 --> 00:43:46,759
Speaker 1: lead or titanium or hydrogen or whatever. But just because

960
00:43:46,760 --> 00:43:48,680
Speaker 1: you put an inch worth of rod doesn't mean the

961
00:43:48,680 --> 00:43:50,120
Speaker 1: event horizon grows an inch.

962
00:43:50,520 --> 00:43:53,239
Speaker 2: So then let's say it's not right. Then if I

963
00:43:53,280 --> 00:43:56,000
Speaker 2: push it an inch into the black hole, am I

964
00:43:56,040 --> 00:43:57,359
Speaker 2: going to see it go into the black hole?

965
00:43:57,400 --> 00:43:59,640
Speaker 1: Then you are because you're pushing it in, right, You're

966
00:43:59,640 --> 00:44:02,040
Speaker 1: not just waiting for the event horizon to grow out

967
00:44:02,080 --> 00:44:04,839
Speaker 1: to gobble it. You're pushing it in. When I say

968
00:44:04,840 --> 00:44:06,560
Speaker 1: the event horizon is growing out. This just to help

969
00:44:06,560 --> 00:44:09,920
Speaker 1: people understand how something can actually fall into the event horizon.

970
00:44:10,280 --> 00:44:12,480
Speaker 1: When an object falls into the event horizon, it's because

971
00:44:12,520 --> 00:44:15,600
Speaker 1: the next thing falling in has pulled the event horizon

972
00:44:15,680 --> 00:44:16,480
Speaker 1: out over it.

973
00:44:16,920 --> 00:44:20,839
Speaker 2: M right, Okay, So then maybe let's not think about

974
00:44:20,880 --> 00:44:23,120
Speaker 2: that scenario. Let's think about the one Steward is thinking about,

975
00:44:23,160 --> 00:44:25,879
Speaker 2: which is sticking your finger into the black hole. See

976
00:44:25,880 --> 00:44:28,200
Speaker 2: if I stick this metal finger into the black hole,

977
00:44:28,239 --> 00:44:28,960
Speaker 2: I would see it going.

978
00:44:29,200 --> 00:44:30,920
Speaker 1: You would see it go in time would slow down

979
00:44:30,960 --> 00:44:33,480
Speaker 1: and it would get red shifted still right, Your finger

980
00:44:33,520 --> 00:44:35,640
Speaker 1: would get redder and redder and darker and darker and

981
00:44:35,680 --> 00:44:39,200
Speaker 1: then eventually invisible right in black. But you would see

982
00:44:39,239 --> 00:44:41,160
Speaker 1: it going. You would have your finger sticking out of

983
00:44:41,160 --> 00:44:41,840
Speaker 1: a black hole.

984
00:44:42,440 --> 00:44:44,360
Speaker 2: It would hurt, or at least the back part of

985
00:44:44,400 --> 00:44:46,919
Speaker 2: your metal indestructible finger is sticking out of the black hole.

986
00:44:47,000 --> 00:44:47,920
Speaker 2: Now what if I pull it?

987
00:44:47,960 --> 00:44:49,960
Speaker 1: Then you're going to have a finger tipless finger?

988
00:44:51,000 --> 00:44:54,600
Speaker 2: You mean I lost my watch? Yeah? Exactly could you

989
00:44:54,600 --> 00:44:54,960
Speaker 2: pull it?

990
00:44:55,000 --> 00:44:55,440
Speaker 5: I guess?

991
00:44:55,600 --> 00:44:58,200
Speaker 2: I guess, yeah, I guess could you? It'd be hard,

992
00:44:58,280 --> 00:44:59,960
Speaker 2: but you could, right, I guess.

993
00:45:00,080 --> 00:45:01,960
Speaker 1: Yeah. If we're talking about a really small black hole,

994
00:45:02,000 --> 00:45:04,520
Speaker 1: one that you could stand next to safely, then it

995
00:45:04,560 --> 00:45:07,279
Speaker 1: actually wouldn't have that much gravity. Like if you take

996
00:45:07,320 --> 00:45:10,239
Speaker 1: the Empire States building and you squeeze it down into

997
00:45:10,239 --> 00:45:12,040
Speaker 1: a black hole, it's going to have as much gravity

998
00:45:12,040 --> 00:45:14,719
Speaker 1: as the Empire States building, and that's not that much, right,

999
00:45:14,719 --> 00:45:17,080
Speaker 1: You can stand next to the mPire States building without

1000
00:45:17,120 --> 00:45:20,320
Speaker 1: like leaning over because if it's gravity, because remember gravity

1001
00:45:20,400 --> 00:45:22,640
Speaker 1: is super duper weak, so even something as big as

1002
00:45:22,640 --> 00:45:24,840
Speaker 1: a building doesn't have that much gravity.

1003
00:45:25,120 --> 00:45:27,319
Speaker 2: Well, but then gravity increases the closer you get to it,

1004
00:45:27,360 --> 00:45:29,399
Speaker 2: so maybe it would still shredd you if you got

1005
00:45:29,560 --> 00:45:30,600
Speaker 2: you know, within an inch of it.

1006
00:45:30,640 --> 00:45:33,000
Speaker 1: Maybe mm hmm. You can get closer to a building

1007
00:45:33,120 --> 00:45:35,560
Speaker 1: mass black hole than you can actually to the center

1008
00:45:35,600 --> 00:45:36,560
Speaker 1: of mass of a building.

1009
00:45:36,880 --> 00:45:39,600
Speaker 2: Absolutely, So then if I stick a metal finger into it,

1010
00:45:40,000 --> 00:45:42,080
Speaker 2: I would see it go in. I could pulk the

1011
00:45:42,120 --> 00:45:44,400
Speaker 2: black hole. But then when I pulled my finger, it

1012
00:45:44,440 --> 00:45:48,000
Speaker 2: will have eaten whatever was inside of the event horizon.

1013
00:45:47,600 --> 00:45:50,120
Speaker 1: And the last things in there would be smeared across

1014
00:45:50,160 --> 00:45:52,480
Speaker 1: the surface of the event horizon because the last thing

1015
00:45:52,520 --> 00:45:54,960
Speaker 1: you tried to stick in would take forever to actually

1016
00:45:55,000 --> 00:45:58,520
Speaker 1: fall in until something else comes along and it pulls

1017
00:45:58,520 --> 00:46:00,360
Speaker 1: out the event horizon over it all?

1018
00:46:00,480 --> 00:46:02,960
Speaker 2: Right, Well, I think that answers Stuart's question. Don't stick

1019
00:46:03,000 --> 00:46:04,000
Speaker 2: your finger in a black hole.

1020
00:46:04,440 --> 00:46:06,920
Speaker 1: Don't stick your finger in a black hole, Stewart, This

1021
00:46:07,000 --> 00:46:09,240
Speaker 1: is not medical advice, but it's physics advice.

1022
00:46:09,480 --> 00:46:12,080
Speaker 2: Well, I wonder if like the black hole is so little,

1023
00:46:12,160 --> 00:46:14,320
Speaker 2: like like you said, with the mass of the empire

1024
00:46:14,360 --> 00:46:16,840
Speaker 2: state building, I imagine it would be you know, super

1025
00:46:16,960 --> 00:46:19,840
Speaker 2: duper tiny small, right, like micron small?

1026
00:46:20,040 --> 00:46:20,200
Speaker 5: Right?

1027
00:46:20,360 --> 00:46:22,480
Speaker 1: Yeah. Absolutely, The masses of the black holes we try

1028
00:46:22,520 --> 00:46:25,799
Speaker 1: to make the large Hadron collider are even tinier, and

1029
00:46:25,960 --> 00:46:30,160
Speaker 1: their event horizons are really really small. Yeah, we're talking microscopic.

1030
00:46:30,440 --> 00:46:32,680
Speaker 2: What happens if you stick your fingers in those, you'll

1031
00:46:32,680 --> 00:46:33,680
Speaker 2: make a hole in your finger.

1032
00:46:33,800 --> 00:46:35,880
Speaker 1: Yeah, I suppose it'd be like a laser beam. But

1033
00:46:35,920 --> 00:46:38,719
Speaker 1: there's another effect there which is really really microscopic. Black

1034
00:46:38,719 --> 00:46:40,759
Speaker 1: holes don't last very long. So if you make a

1035
00:46:40,760 --> 00:46:44,439
Speaker 1: black hole that's really really small, it'll hawking radiation away

1036
00:46:44,480 --> 00:46:47,280
Speaker 1: its mass really really fast, because the rate of hawking

1037
00:46:47,360 --> 00:46:51,120
Speaker 1: radiation depends on the temperature, which is inversely proportional to

1038
00:46:51,160 --> 00:46:54,480
Speaker 1: the mass, So really small black holes are hotter and

1039
00:46:54,600 --> 00:46:57,879
Speaker 1: have more hawking radiation, so they actually don't last very long.

1040
00:46:58,080 --> 00:47:00,400
Speaker 2: So you'd have to have a fast finger. You have

1041
00:47:00,520 --> 00:47:03,480
Speaker 2: to be pretty quick pok it before it evaporates.

1042
00:47:03,719 --> 00:47:05,440
Speaker 1: You'd have to be determined to hurt yourself.

1043
00:47:05,719 --> 00:47:08,919
Speaker 2: All right, Well, I think that answers Stuart's question. It's

1044
00:47:08,920 --> 00:47:11,799
Speaker 2: sort of It's not necessarily the case that you would

1045
00:47:11,800 --> 00:47:13,960
Speaker 2: never see what happens. You would see what happens if

1046
00:47:14,000 --> 00:47:15,319
Speaker 2: you start something into a black hole.

1047
00:47:15,400 --> 00:47:17,360
Speaker 1: That's right. If you manage to somehow s arrive getting

1048
00:47:17,400 --> 00:47:20,040
Speaker 1: next to a black hole, you can actually stick stuff

1049
00:47:20,040 --> 00:47:21,200
Speaker 1: into it and lose.

1050
00:47:21,000 --> 00:47:23,439
Speaker 2: It, and then the joke would be on the black hole.

1051
00:47:24,280 --> 00:47:26,200
Speaker 2: You can make the fart sound if you like, but

1052
00:47:26,280 --> 00:47:28,040
Speaker 2: I guess the black hole keeps your fingers, so then

1053
00:47:28,360 --> 00:47:29,279
Speaker 2: the joke's on.

1054
00:47:29,360 --> 00:47:29,560
Speaker 5: You.

1055
00:47:29,880 --> 00:47:31,600
Speaker 1: Don't try this at home, folks, but.

1056
00:47:31,600 --> 00:47:34,000
Speaker 2: Do try it in a large particle collider. I don't

1057
00:47:34,040 --> 00:47:35,000
Speaker 2: understand the message here.

1058
00:47:35,000 --> 00:47:37,480
Speaker 1: Well, if those black holes are actually made, they would

1059
00:47:37,480 --> 00:47:41,160
Speaker 1: evaporate very, very rapidly because they're super duber tiny.

1060
00:47:41,440 --> 00:47:43,440
Speaker 2: Just don't let Stuart near them because he might want

1061
00:47:43,480 --> 00:47:46,759
Speaker 2: us stick his fingers quickly before they evaporate. All right, Well,

1062
00:47:46,840 --> 00:47:49,400
Speaker 2: those are three awesome questions. Thanks again to our listeners

1063
00:47:49,400 --> 00:47:51,160
Speaker 2: for sending us these amazing questions.

1064
00:47:51,400 --> 00:47:54,000
Speaker 1: Thank you everybody out there for being curious and wondering

1065
00:47:54,040 --> 00:47:55,840
Speaker 1: about the nature of the world, which is the reason

1066
00:47:55,880 --> 00:47:58,200
Speaker 1: why we get to do science and think about how

1067
00:47:58,239 --> 00:48:01,359
Speaker 1: the universe works. You have a question about how something works,

1068
00:48:01,400 --> 00:48:04,000
Speaker 1: Please don't be shy. Send it to us to questions

1069
00:48:04,000 --> 00:48:05,840
Speaker 1: at danielanjorgey dot com.

1070
00:48:05,920 --> 00:48:08,040
Speaker 2: Yeah, as you sit out there in the long call

1071
00:48:08,120 --> 00:48:10,759
Speaker 2: of life wondering about the universe, staring out at the sky,

1072
00:48:10,880 --> 00:48:13,480
Speaker 2: wondering what you can stick your finger in, just remember

1073
00:48:13,640 --> 00:48:14,680
Speaker 2: it's an amazing.

1074
00:48:14,400 --> 00:48:17,120
Speaker 1: Universe and dip your French fries into shakes, not into

1075
00:48:17,160 --> 00:48:17,800
Speaker 1: black holes.

1076
00:48:17,880 --> 00:48:20,320
Speaker 2: Oh what would happen then? Would they still be French?

1077
00:48:20,600 --> 00:48:21,520
Speaker 1: They wouldn't be crunchy.

1078
00:48:21,800 --> 00:48:26,760
Speaker 2: It would be decapitated, beheaded like in the French Revolution.

1079
00:48:27,400 --> 00:48:29,279
Speaker 2: All right, Well, we hope you enjoyed that. Thanks for

1080
00:48:29,360 --> 00:48:31,520
Speaker 2: joining us, See you next time.

1081
00:48:39,400 --> 00:48:42,200
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

1082
00:48:42,280 --> 00:48:46,200
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts

1083
00:48:46,280 --> 00:48:50,920
Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

1084
00:48:51,000 --> 00:48:52,720
Speaker 1: you listen to your favorite shows.