Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 41: Questions about the mass of the Universe, moons made of gas, and backyard blackholes.

Transcript

Listener Questions 41: Questions about the mass of the Universe, moons made of gas, and backyard blackholes. · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Jorgey, how is your commute to work this morning?
• 0:11
  Speaker 2: Pretty short? Taking me about one or two minutes?
• 0:14
  Speaker 1: Is that your typical commune? Do you ever get stuck
• 0:16
  Speaker 1: in traffic and take like a whole five or six minutes?
• 0:19
  Speaker 2: Well, there can be a jam up in the kitchen
• 0:21
  Speaker 2: sometimes usually blueberry jam.
• 0:23
  Speaker 1: Well, I hope your traffic is only caused by the
• 0:25
  Speaker 1: tastiest kinds of accidents, like spilled nutella.
• 0:29
  Speaker 2: Yeah, it's a short community, but it can get kind
• 0:31
  Speaker 2: of nutty.
• 0:32
  Speaker 1: Only the most delicious of delays.
• 0:34
  Speaker 2: Nothing like tasty traffic. I am Horae. I'm the cartoonist
• 0:52
  Speaker 2: and the author of Oliver's Great Big Universe.
• 0:55
  Speaker 1: Hi, I'm Daniel. I'm a particle physicist and a professor
• 0:58
  Speaker 1: at UC Irvine, and I think think the whole universe
• 1:01
  Speaker 1: is pretty tasty.
• 1:02
  Speaker 2: What does it taste like? Though? Salty? Sweet? Bitter?
• 1:06
  Speaker 1: Astronauts tell us that space smells like barbecue.
• 1:08
  Speaker 2: So it's a umami universe.
• 1:12
  Speaker 1: Exactly. It sounds like it's more savory than sweet.
• 1:14
  Speaker 2: Spacey savory.
• 1:17
  Speaker 1: It's more French fry than milkshake.
• 1:19
  Speaker 2: Got there, I think, or it's French fries with milkshakes.
• 1:21
  Speaker 1: That's what happens in the multiverse when we cross our
• 1:24
  Speaker 1: savory universes with some of the other sweet ones.
• 1:26
  Speaker 2: That's what happens every time I go to McDonald's. Do
• 1:28
  Speaker 2: you ever dip your French fries in milkshake or ice cream?
• 1:31
  Speaker 1: I'm much of a fan of soggy French.
• 1:33
  Speaker 2: Fries, so no, you're missing up. But anyways, welcome to
• 1:38
  Speaker 2: our podcast, Daniel and Jorge Explain the Universe, a production
• 1:40
  Speaker 2: of iHeartRadio.
• 1:41
  Speaker 1: In which we sample all of the flavors of the universe,
• 1:45
  Speaker 1: everything that crunches, everything that crisps, everything that gets soggy
• 1:49
  Speaker 1: when you dip it into a milkshake. We think about
• 1:51
  Speaker 1: the tiniest quantum particles what they are really doing. We
• 1:54
  Speaker 1: think about how fluid flows around you on the surface
• 1:57
  Speaker 1: of the Earth, and we think about the centers of
• 1:59
  Speaker 1: black hole. Our goal is to embrace our curiosity, to
• 2:02
  Speaker 1: think widely about everything out there that makes us wonder,
• 2:06
  Speaker 1: and to talk to you about what we do and
• 2:08
  Speaker 1: don't know about what's happening.
• 2:10
  Speaker 2: That's right. It is a pretty amazing universe. And the
• 2:13
  Speaker 2: universe is everywhere all around you. In fact, even inside
• 2:16
  Speaker 2: of you. The universe is full of amazing facts and
• 2:19
  Speaker 2: questions for us to ask and possibly maybe sometimes answer, like,
• 2:23
  Speaker 2: for example, if you're an alien, do French fries become
• 2:27
  Speaker 2: Earth fries?
• 2:27
  Speaker 1: You know, I'm amazed at our abilities to continually generate
• 2:30
  Speaker 1: new questions that nobody has ever asked before, like that one.
• 2:36
  Speaker 2: Do I get a noble price for asking questions? Or
• 2:40
  Speaker 2: maybe depends on where you're from as an alien, like
• 2:42
  Speaker 2: if you're from Andromeda, do they become Milky Way pries?
• 2:46
  Speaker 1: But you know, sometimes these foods are not well named,
• 2:49
  Speaker 1: like the pastry that in America we call a Danish.
• 2:52
  Speaker 1: The Danish people don't call an American pastry. They actually
• 2:56
  Speaker 1: call it a Vienna pastry.
• 2:57
  Speaker 2: Wait what and what do they call it in Vienna?
• 3:00
  Speaker 2: A US pastry?
• 3:02
  Speaker 1: I think they call it a VNS so they take
• 3:04
  Speaker 1: credit for it. But we named it after the Danish.
• 3:07
  Speaker 2: Well, you know, history goes to the conquerors, I guess.
• 3:10
  Speaker 2: So whoever first discovered the Danish maybe they discovered it
• 3:14
  Speaker 2: in Denmark and then they got to call it the Danish.
• 3:16
  Speaker 1: And I've heard that there's a long debate about the
• 3:18
  Speaker 1: French fry whether it's actually invented in France or in Belgium.
• 3:22
  Speaker 2: But don't they speak French in Belgium, so technically they
• 3:25
  Speaker 2: would still call it pomfrets. So yeah, it's still a
• 3:29
  Speaker 2: French fry.
• 3:31
  Speaker 1: I'm going to stay out of that colonial and political discussion.
• 3:35
  Speaker 2: You know, let's stick to the universe instead, simpler things
• 3:39
  Speaker 2: like everything.
• 3:40
  Speaker 1: If Aliens are mad at us for calling them French fries,
• 3:42
  Speaker 1: at least they're not going to write angry emails to us.
• 3:45
  Speaker 2: Why would they get angry? If anything, it would be
• 3:47
  Speaker 2: the French.
• 3:53
  Speaker 1: I love all the French people and all the Belgian
• 3:55
  Speaker 1: people and all their cuisine and their culture.
• 3:57
  Speaker 2: But not the Danish. The Danish, you want to steal
• 4:02
  Speaker 2: their national pastry away from them.
• 4:04
  Speaker 1: They don't claim it as their national pastry. They call
• 4:06
  Speaker 1: it a Vienna pastry. It's not part of their national pride.
• 4:11
  Speaker 2: What do they called Vienna sausages? Then Danish sausage?
• 4:14
  Speaker 1: You mean wieners in a can. I don't think anybody
• 4:16
  Speaker 1: wants to take credit for that.
• 4:17
  Speaker 2: That's a whole separate universe. But yeah, the universe is
• 4:19
  Speaker 2: full of amazing questions for scientists to ask and also
• 4:23
  Speaker 2: everyday people to ask.
• 4:24
  Speaker 1: These questions we ask about the universe are questions that
• 4:27
  Speaker 1: people have been asking for generations, sometimes for thousands of years.
• 4:31
  Speaker 1: How big is the universe? How does it all work?
• 4:33
  Speaker 1: What's out there waiting for us? Are we alone? Because
• 4:36
  Speaker 1: it's just part of being human to look out of
• 4:39
  Speaker 1: the universe and want to understand it, to generate questions,
• 4:43
  Speaker 1: to have that wonder bubble up inside of you. And
• 4:46
  Speaker 1: it's not just professional scientists and cartoonists who are asking
• 4:49
  Speaker 1: these questions. It's everybody. It's you.
• 4:52
  Speaker 2: Yeah, it does seem to be kind of a human
• 4:54
  Speaker 2: quality curiosity in asking questions about the universe. I mean,
• 4:57
  Speaker 2: you don't see a lot of other animals asking questions
• 4:59
  Speaker 2: or doing research, right, I don't know.
• 5:00
  Speaker 1: I see curiosity in cats and dogs, even rats. There's
• 5:04
  Speaker 1: definitely curiosity out there.
• 5:06
  Speaker 2: You think cats wonder about the origin of the universe,
• 5:09
  Speaker 2: but gravity, the nature of space and time.
• 5:12
  Speaker 1: I think they wonder why their dinner is late. Yeah.
• 5:14
  Speaker 2: Yeah, they're just wondering how to kill you probably if
• 5:17
  Speaker 2: they could.
• 5:18
  Speaker 1: You could call that experimentation, you know.
• 5:21
  Speaker 2: Yeah, murders a feline experimentation FI. But yeah, everybody has questions,
• 5:27
  Speaker 2: and sometimes on this podcast we like to answer them.
• 5:29
  Speaker 1: We love to answer questions. If you are wondering something
• 5:32
  Speaker 1: about the nature of the universe, or there's something that
• 5:35
  Speaker 1: doesn't quite click in your mind. We want to help
• 5:37
  Speaker 1: you make its stap together. So please write to us
• 5:41
  Speaker 1: with your questions to questions at Danielandjorge dot com. When
• 5:45
  Speaker 1: we say it all the time, but we really mean it,
• 5:47
  Speaker 1: we love your questions. We answer all of them, and
• 5:50
  Speaker 1: if there's a question that's especially interesting or I think
• 5:52
  Speaker 1: a lot of people might want to hear the answer to,
• 5:55
  Speaker 1: we will even play it here on the podcast and
• 5:57
  Speaker 1: joke about it.
• 5:58
  Speaker 2: So today on the podcast will be Listener Questions number
• 6:07
  Speaker 2: forty one. Maybe we should stop numbering these question episodes.
• 6:13
  Speaker 2: I feel like at forty one we can probably stop counting,
• 6:16
  Speaker 2: or maybe we should stop with forty two, because that
• 6:18
  Speaker 2: is the answer.
• 6:20
  Speaker 1: That's right and everything. Well. Number them helps me keep
• 6:23
  Speaker 1: track of them, because otherwise I'll get confused about whether
• 6:25
  Speaker 1: or not we already answered a question or not.
• 6:28
  Speaker 2: Oh, I see, so I least itselful for one person, yes, exactly,
• 6:33
  Speaker 2: out of the entire universe.
• 6:35
  Speaker 1: And this way I can refer listeners. I can say,
• 6:37
  Speaker 1: check out Listener Questions twenty four, where we talked about
• 6:40
  Speaker 1: exactly that topic.
• 6:41
  Speaker 2: Oh, I see, they're like issues of a comic book,
• 6:44
  Speaker 2: like ooh, have you heard listener questions number thirty seven?
• 6:48
  Speaker 2: That's the one where the dark Phoenix rises from the ashes.
• 6:52
  Speaker 1: That's the one where we reveal that Jorge is actually Superman.
• 6:56
  Speaker 2: That's right. Do you think maybe these will be collector
• 6:58
  Speaker 2: items someday? Maybe we should make NFTs out of these episodes.
• 7:02
  Speaker 1: I think it's more likely that the aliens come and
• 7:04
  Speaker 1: make French fries out of us.
• 7:05
  Speaker 2: Than somebody would ever want to collect our podcast. Maybe
• 7:10
  Speaker 2: we should record a new French then.
• 7:12
  Speaker 1: But we really do love hearing your questions and thinking
• 7:15
  Speaker 1: about them and answering them. So let me just say again,
• 7:18
  Speaker 1: please don't be shy to write to us questions at
• 7:20
  Speaker 1: Danielandjorge dot com.
• 7:22
  Speaker 2: Yeah, so today we're answering questions from listeners and give
• 7:25
  Speaker 2: them some kind of answer at least, And we have
• 7:28
  Speaker 2: some pretty awesome questions here about the mass of the universe,
• 7:31
  Speaker 2: about gases, about moons made out of gas, and also
• 7:36
  Speaker 2: what would happen if you stuck your finger in a
• 7:38
  Speaker 2: black hole? A physical black hole I imagine.
• 7:40
  Speaker 1: As opposed to what a French fried black hole.
• 7:42
  Speaker 2: I don't know, a metaphorical black hole or something called
• 7:47
  Speaker 2: a black hole, but it's not really a black hole.
• 7:48
  Speaker 1: Mmmm. I see.
• 7:49
  Speaker 2: You just got to be in general careful about what
• 7:51
  Speaker 2: do you mean when you say stick your finger in things?
• 7:54
  Speaker 1: That's true. Some of these questions are a figurative rabbit hole.
• 7:57
  Speaker 2: Yeah, you gotta watch out for those two, because the
• 7:59
  Speaker 2: rabbit might your finger if you stick your finger in it.
• 8:01
  Speaker 2: So let's get to it. Our first question comes from Eric.
• 8:04
  Speaker 3: Hello, Daniel and Jore. I'm a big fan of your podcast.
• 8:08
  Speaker 3: I'm a line hauled truck driver who delivers freight from
• 8:12
  Speaker 3: Utah to Idaho. My question is how many tons of
• 8:15
  Speaker 3: mass would my rig have to pull if I were
• 8:18
  Speaker 3: to drag the whole universe up to Idaho rather than
• 8:21
  Speaker 3: delivering it a few pieces at a time. Please include
• 8:25
  Speaker 3: dark matter in your calculations, though I understand it would
• 8:28
  Speaker 3: be difficult to secure in place. Thank you and keep
• 8:32
  Speaker 3: up the good work.
• 8:33
  Speaker 2: All right, Thank you, Eric. That's an awesome question. And
• 8:35
  Speaker 2: I love that he's a long haul trucker.
• 8:37
  Speaker 1: He's out there delivering those fresh strawberries.
• 8:39
  Speaker 2: Yeah, or do you think he maybe sometimes cargoes frenchies?
• 8:43
  Speaker 1: Is really those long haul truck drivers that make our
• 8:45
  Speaker 1: economy work and keep everybody's shelves stocked. So thanks to
• 8:49
  Speaker 1: all the truckers who keep us fed.
• 8:51
  Speaker 2: Yeah, keep on trucking, and I guess we're happy to
• 8:53
  Speaker 2: keep those truckers entertaining thinking about the universe as they
• 8:56
  Speaker 2: drive those long stretches of road between states.
• 9:00
  Speaker 1: Yeah. One thing makes me worried, though, because a lot
• 9:02
  Speaker 1: of people write in and say that our podcast is
• 9:04
  Speaker 1: very nice to fall asleep to, gives them pleasant dreams
• 9:07
  Speaker 1: or whatever, and I really don't want long haul truckers
• 9:10
  Speaker 1: drifting off while they listen to us joke about the universe.
• 9:13
  Speaker 2: Has anybody ever written to say our podcast helps them
• 9:16
  Speaker 2: stay awake or it rarely happens.
• 9:19
  Speaker 1: I haven't gotten one of those messages yet, but I
• 9:22
  Speaker 1: hope it does that.
• 9:23
  Speaker 2: For Eric. Well, if you're a long haul trucker right
• 9:25
  Speaker 2: now listening to this, wake.
• 9:28
  Speaker 1: Up, don't alarm them, man, keep your.
• 9:31
  Speaker 2: Eyes on the road, that's right, don't look up it's
• 9:35
  Speaker 2: the night sky or at space too much.
• 9:38
  Speaker 1: But Eric asks a really fun question basically about the
• 9:41
  Speaker 1: mass of the whole universe, and I like how he
• 9:43
  Speaker 1: thinks about it in terms of how much his truck
• 9:45
  Speaker 1: can pull.
• 9:46
  Speaker 2: Yeah, it's kind of a funny question. His question is
• 9:48
  Speaker 2: how many tons of mass would his truck have to
• 9:52
  Speaker 2: pull if it had to pull the whole universe from
• 9:55
  Speaker 2: you to to Idaho. I guess that's a very specific.
• 9:57
  Speaker 1: Move they make in Utah. The people in Idaho especially
• 10:02
  Speaker 1: want because it's not potatoes, right. If anything, those are
• 10:05
  Speaker 1: going in the other direction.
• 10:06
  Speaker 2: Sounds like Eric got a request for a quote. Somebody
• 10:10
  Speaker 2: ordered the universe in Idaho.
• 10:11
  Speaker 1: Maybe he brings salt from Salt Lake City to Boise
• 10:14
  Speaker 1: and comes back with potatoes.
• 10:16
  Speaker 2: Right. They ran out of potatoes in Idaho, so they
• 10:18
  Speaker 2: need to import a whole universe of them from Utah.
• 10:22
  Speaker 1: No, dude, it must be the opposite. Idaho is where
• 10:25
  Speaker 1: potatoes grow.
• 10:26
  Speaker 2: That's what I mean. They ran out of potatoes in Iao,
• 10:29
  Speaker 2: so they had to import some from a different universe.
• 10:32
  Speaker 2: I guess.
• 10:33
  Speaker 1: I do think that Utah is a bit of a
• 10:34
  Speaker 1: different universe than Idaho.
• 10:36
  Speaker 4: Oh.
• 10:36
  Speaker 2: I think they're both different universes. Every state is a
• 10:39
  Speaker 2: different universe.
• 10:40
  Speaker 1: They're both beautiful, though, I've been to both. Gorgeous mountains everywhere.
• 10:43
  Speaker 2: But it's an interesting question, I guess. Really he's asking
• 10:46
  Speaker 2: how much does the universe weigh, or how much masses
• 10:49
  Speaker 2: there in the entire universe as far as we know.
• 10:52
  Speaker 1: Yeah, it's a really interesting question, and he thinks about
• 10:54
  Speaker 1: it in terms of his truck. A typical semi can
• 10:57
  Speaker 1: haul about fifteen thousand kilogram of stuff. But the universe,
• 11:01
  Speaker 1: of course, much much bigger than that. And I don't
• 11:04
  Speaker 1: even know how many muches I need to say to
• 11:07
  Speaker 1: give you the sense for how much bigger the universe is.
• 11:10
  Speaker 1: The actual number is that the mass of the part
• 11:12
  Speaker 1: of the universe that we can see is about ten
• 11:15
  Speaker 1: to the fifty three kilograms. So that's ten with fifty
• 11:19
  Speaker 1: three zeros in front of it, whereas his truck can
• 11:22
  Speaker 1: haul fifteen with three zeros in front of it. So
• 11:26
  Speaker 1: it's a lot bigger than what he can pull.
• 11:27
  Speaker 2: Yeah, I think he probably understands that this truck can
• 11:30
  Speaker 2: pull the whole universe. But I think he's asking how
• 11:32
  Speaker 2: much mass would his truck be required to pull if
• 11:36
  Speaker 2: he had to move it from you to Idaho. I
• 11:38
  Speaker 2: think he knows.
• 11:40
  Speaker 1: I'm pretty sure he knows, but the quantity is really staggering.
• 11:42
  Speaker 1: I mean, it's the case where like a kilogram is
• 11:44
  Speaker 1: really the wrong unit. To think about the mass of
• 11:46
  Speaker 1: the universe, a kilogram is like something you could hold
• 11:49
  Speaker 1: in your hand, So ten to the fifty three is
• 11:51
  Speaker 1: just too big a number to think about. If you
• 11:52
  Speaker 1: think about the universe in terms of like loads of
• 11:55
  Speaker 1: Eric's truck, his truck can pull about fifteen thousand kilograms.
• 11:58
  Speaker 1: That still comes out to like ten to forty nine truckloads.
• 12:01
  Speaker 1: So it's still a really really big number.
• 12:03
  Speaker 2: Oh you mean, like if he took the universe broke
• 12:06
  Speaker 2: it down into different pallets, how many trips would we
• 12:09
  Speaker 2: have to make to move the whole universe?
• 12:11
  Speaker 1: Exactly? So moving the whole universe would require moving ten
• 12:14
  Speaker 1: to the fifty three kilograms. Clearly impossible if he did
• 12:18
  Speaker 1: break it down. I know, Eric, you want to do
• 12:20
  Speaker 1: it all in one hall, But if you did break
• 12:21
  Speaker 1: it down into chunks your truck could actually handle, it
• 12:24
  Speaker 1: would take about ten to the forty nine truckloads.
• 12:28
  Speaker 2: And how long does each trip take?
• 12:29
  Speaker 1: So it's about five hours from Salt Lake City to Boise.
• 12:32
  Speaker 1: I'm not sure exactly where he's driving, which makes it
• 12:35
  Speaker 1: like a ten hour round trip. Now if he never sleeps,
• 12:38
  Speaker 1: and that means he has about time for nine hundred
• 12:40
  Speaker 1: trips in a year back and forth, so it's like
• 12:43
  Speaker 1: almost a thousand trips a year. But it's going to
• 12:46
  Speaker 1: take him ten to the forty nine truckloads. That comes
• 12:49
  Speaker 1: out to ten to the forty seven years of driving
• 12:53
  Speaker 1: back and forth, NonStop, no sleeping, no bathroom breaks, to
• 12:57
  Speaker 1: bring the whole universe back and forth between Salt Lakes
• 13:00
  Speaker 1: and Boise.
• 13:01
  Speaker 2: Oh man, but can he listen to our podcast while
• 13:03
  Speaker 2: he's driving? Might make him drive faster. He's like, oh God,
• 13:07
  Speaker 2: this is torture. I just want to get this over with.
• 13:10
  Speaker 2: I have to listen to this podcast.
• 13:11
  Speaker 1: You know, we got like five hundred hours of podcast
• 13:14
  Speaker 1: out there. But even still, he would run out pretty quick.
• 13:16
  Speaker 1: He would have to listen to every episode a lot
• 13:18
  Speaker 1: of times.
• 13:19
  Speaker 2: Interesting. I guess maybe the question is how do we
• 13:22
  Speaker 2: know how much the universe ways? First of all, we
• 13:25
  Speaker 2: don't know if the universe is finite or infinite, right.
• 13:27
  Speaker 1: We certainly don't. The universe could be infinitive, could go
• 13:30
  Speaker 1: on forever, or it could also be finite. The part
• 13:33
  Speaker 1: of the universe that we can see, what we call
• 13:36
  Speaker 1: the observable universe, is just the part where light has
• 13:39
  Speaker 1: had time to get to us from those far reaches
• 13:42
  Speaker 1: beyond that we literally can't see because even though it
• 13:45
  Speaker 1: might exist and photons from it could be racing through
• 13:48
  Speaker 1: space to reach us, it hasn't arrived yet because the
• 13:51
  Speaker 1: universe it's only like fourteen billion years old, so photons
• 13:55
  Speaker 1: that take fifteen billion years to get here haven't arrived. Yets,
• 13:58
  Speaker 1: we haven't seen that part of the universe. So there's
• 14:01
  Speaker 1: like a sphere surrounding us that we call the observable universe,
• 14:05
  Speaker 1: and that's the part we can see, and we can
• 14:07
  Speaker 1: measure how much stuff is in it, and so we
• 14:09
  Speaker 1: can talk about the mass of that part. But that
• 14:12
  Speaker 1: could be literally a zero percent fraction of the infinite universe,
• 14:16
  Speaker 1: or it could be most of the stuff that's out there.
• 14:18
  Speaker 1: We don't know what's beyond the boundary of the observable.
• 14:22
  Speaker 2: Yeah, the universe can be pretty big, but I guess
• 14:25
  Speaker 2: then the question is how do we know how much
• 14:26
  Speaker 2: it weighs or how much mass it has, Like we
• 14:28
  Speaker 2: have a hard time knowing exactly how much mass the
• 14:31
  Speaker 2: Earth has, right, Didn't we have a whole episode about that?
• 14:34
  Speaker 1: Yeah, we did have an episode about measuring the gravitational constant,
• 14:37
  Speaker 1: and that's a fun episode because we talk about how
• 14:39
  Speaker 1: they're trying to make that very very precise. What we
• 14:41
  Speaker 1: do when we measure the universe is that we measure
• 14:43
  Speaker 1: the typical energy density, like how much stuff is there
• 14:47
  Speaker 1: in a cubic light year of space an average cubic
• 14:50
  Speaker 1: light year of space. So we go out there and
• 14:53
  Speaker 1: we look at like all the stars and the gas
• 14:55
  Speaker 1: and the dust, and we add up all the dark
• 14:57
  Speaker 1: matter as Eric suggested that we include, and we measured
• 15:00
  Speaker 1: that by looking at how like galaxy swirl and the
• 15:03
  Speaker 1: large scale structure the universe which is influenced by dark matter.
• 15:06
  Speaker 1: We also add of the energy of the expansion dark energy.
• 15:10
  Speaker 1: So there's all these different components of the sort of
• 15:13
  Speaker 1: energy budget of the universe. Some of them we can
• 15:15
  Speaker 1: measure independently, some of them we measure together. All of
• 15:18
  Speaker 1: them we have multiple different ways of measuring. So we're
• 15:21
  Speaker 1: pretty confident we know all those various pieces of the pie.
• 15:24
  Speaker 2: But I think Eric is asking about the mass of
• 15:27
  Speaker 2: the universe, not the energy of it, right, because like
• 15:29
  Speaker 2: energy doesn't necessarily have to haul if we have to
• 15:31
  Speaker 2: move it from Utah to Idaho.
• 15:32
  Speaker 1: Yeah, that's right. There's different components is matter. There's radiation,
• 15:35
  Speaker 1: there's dark energy, so just the matter part of it, right,
• 15:38
  Speaker 1: we can measure that as well. Just the matter part
• 15:40
  Speaker 1: we can measure separately. And we've done that.
• 15:42
  Speaker 2: How do we do that? Like, how do we even
• 15:44
  Speaker 2: know how much the Earth weighs? Sorry? Giant scale? We
• 15:47
  Speaker 2: can put the whole earth on.
• 15:48
  Speaker 1: Well, once we measure the gravitational constant, which required using
• 15:51
  Speaker 1: like a pendulum and a weird mountain in Scotland that
• 15:55
  Speaker 1: we knew the density of, then we could measure the
• 15:57
  Speaker 1: mass of the Earth by understanding how it moves or
• 16:00
  Speaker 1: on the Sun. Because once you have the gravitational constant,
• 16:03
  Speaker 1: do you know the force?
• 16:04
  Speaker 2: But when do we need to know? Also the mass
• 16:05
  Speaker 2: of the Sun and how do we know that?
• 16:07
  Speaker 1: So the mass in general of stars we can connect
• 16:09
  Speaker 1: to their brightness because there's a model that tells us
• 16:12
  Speaker 1: that brighter stars are heavier, and that's somewhat theoretical but
• 16:17
  Speaker 1: also pretty well established. So in general we can tell
• 16:20
  Speaker 1: the mass of stars by looking at how bright they are.
• 16:22
  Speaker 2: Interesting, but it's based on a theory sort of, right.
• 16:25
  Speaker 1: Yeah, it is based on a theory. We have this
• 16:27
  Speaker 1: theory of how stars form, how they operate, how the
• 16:29
  Speaker 1: mass of those stars determines their temperature, which it determines
• 16:32
  Speaker 1: how bright they are. It has to do with how
• 16:34
  Speaker 1: fusion happens at various temperatures, and that works pretty well.
• 16:38
  Speaker 1: Of course, there's still big unanswered questions about what's going
• 16:40
  Speaker 1: on at the heart of star, the plasma flux tubes
• 16:43
  Speaker 1: that are snapping in the magnetic fields that don't really
• 16:45
  Speaker 1: make any sense. But on the whole, we're pretty confident
• 16:47
  Speaker 1: in our understanding of how massive stars are. Sometimes we
• 16:51
  Speaker 1: get lucky we see like a binary star system, and
• 16:53
  Speaker 1: we can use that to calibrate this because by the
• 16:56
  Speaker 1: relative motion we understand their masses.
• 16:58
  Speaker 2: M okay, stars that they're What about like planets and
• 17:03
  Speaker 2: gas and dost like? Have we measured the mass of
• 17:05
  Speaker 2: planets around other stars or do we just sort of
• 17:07
  Speaker 2: ignore that it's in say it's negligible.
• 17:09
  Speaker 1: That really is negligible, Like even in our Solar system,
• 17:12
  Speaker 1: the mass of things that are not the Sun is
• 17:14
  Speaker 1: about one percent. We can measure the mass of some
• 17:17
  Speaker 1: planets around other stars because we can see their size
• 17:21
  Speaker 1: as they eclipse their star, and we can get their
• 17:23
  Speaker 1: mass from the period, and so that tells us their
• 17:25
  Speaker 1: density et cetera. Et cetera. So we can study a
• 17:27
  Speaker 1: few planets outside our solar system, but on the whole
• 17:30
  Speaker 1: we have not observed very many of them. But mostly
• 17:33
  Speaker 1: it's stars. And then there's gas and dust. A huge
• 17:35
  Speaker 1: fraction of the mass of the universe that's not dark matter,
• 17:38
  Speaker 1: just the normal mass, is in gas and dust. A
• 17:42
  Speaker 1: lot of that is in galaxies, but also a lot
• 17:44
  Speaker 1: of that is between galaxies, Like the gas that flows
• 17:48
  Speaker 1: between galaxies that's still falling into galaxies is a huge
• 17:52
  Speaker 1: fraction of the normal matter in the universe.
• 17:55
  Speaker 2: And then how do you measure that. I mean, it's
• 17:56
  Speaker 2: so far away and it doesn't shine like a star.
• 18:00
  Speaker 2: Do you know how much of that stuff is out there?
• 18:01
  Speaker 1: That's pretty difficult to measure because it's diffuse. One way
• 18:04
  Speaker 1: we can do it is by looking at quasars. Quasars
• 18:07
  Speaker 1: send out these bright rays of light, these like pencil
• 18:10
  Speaker 1: beams of light, and when they pass through these filaments,
• 18:13
  Speaker 1: they get distorted, or they get diffracted, or they get bent.
• 18:16
  Speaker 1: So in some cases we have these beams that penetrate
• 18:18
  Speaker 1: this cosmic web and give us a measurement for what's there,
• 18:22
  Speaker 1: though it can be pretty tricky and those are pretty
• 18:24
  Speaker 1: rare so again we have models that describe like the
• 18:27
  Speaker 1: overall evolution of the universe, like the large scale structure
• 18:30
  Speaker 1: of the universe that tell us roughly how much gas
• 18:33
  Speaker 1: there is, but a lot of it has not been
• 18:35
  Speaker 1: directly seen. We actually had a fun episode about how
• 18:38
  Speaker 1: slime molds teach us about the large scale structure of
• 18:41
  Speaker 1: the universe and where these cosmic filaments are because they
• 18:44
  Speaker 1: tend to form in patterns that are similar to that
• 18:47
  Speaker 1: cosmic structure, but a lot of it is not observed.
• 18:50
  Speaker 1: It's extrapolated from a few observations.
• 18:52
  Speaker 2: So then you extrapolate that to hold galaxies, Like how
• 18:55
  Speaker 2: do you know how much mass is in a galaxy?
• 18:58
  Speaker 2: You only see di ferent far away.
• 19:00
  Speaker 1: We can measure the mass of a galaxy by looking
• 19:01
  Speaker 1: at the brightness of the stars, which tells us the
• 19:03
  Speaker 1: mass of the stars, then also watching its spin, which
• 19:06
  Speaker 1: tells us how much invisible mass there is. Because most
• 19:09
  Speaker 1: of the mass of most galaxies is actually in dark matter,
• 19:12
  Speaker 1: like eighty to ninety percent, and that we can't see
• 19:15
  Speaker 1: directly in any way. We can only see its gravitational
• 19:18
  Speaker 1: effects on the rest of the galaxy. So galaxies that
• 19:20
  Speaker 1: are spinning really really fast The only way to understand
• 19:23
  Speaker 1: why they are held together, why they're not throwing their
• 19:25
  Speaker 1: stars into intergalactic space, is to imagine that they have
• 19:28
  Speaker 1: a lot of dark matter in them. Sometimes we can
• 19:31
  Speaker 1: also see that dark matter directly through gravitational lensing, as
• 19:35
  Speaker 1: it distorts the light from other background galaxies.
• 19:38
  Speaker 2: I'm sort of getting the idea that you don't know
• 19:40
  Speaker 2: how much the universe wasays. A lot of it seems
• 19:44
  Speaker 2: sort of based on theories and models and what we
• 19:47
  Speaker 2: think is out there, but it sort of doesn't feel
• 19:49
  Speaker 2: like you've gone out there and measured how much mass
• 19:52
  Speaker 2: there is.
• 19:52
  Speaker 1: There's definitely a lot of extrapolation. And you know, something
• 19:55
  Speaker 1: that's happened recently is that cosmology has become a precision science.
• 19:58
  Speaker 1: It used to be the cosmologist people who think about
• 20:00
  Speaker 1: like the whole universe only really cared about getting answers
• 20:03
  Speaker 1: correct within like a factor of two or factor of five.
• 20:06
  Speaker 1: You know, that was precision cosmology a few decades ago.
• 20:10
  Speaker 1: These days, things have gotten better, and now we can
• 20:12
  Speaker 1: measure these things down to like five percent, one percent,
• 20:15
  Speaker 1: a tenth of one percent, and we're being more and
• 20:18
  Speaker 1: more careful about those uncertainties, asking questions like you're asking, like,
• 20:21
  Speaker 1: how do we really know them? Could we be getting
• 20:23
  Speaker 1: this wrong and in what ways? And do we have
• 20:25
  Speaker 1: another way to test this independently? So cosmology has really
• 20:29
  Speaker 1: become more and more precise, and you're certainly right that
• 20:31
  Speaker 1: we don't know exactly how much mass there is in
• 20:34
  Speaker 1: the universe. We have a pretty good picture to within,
• 20:36
  Speaker 1: you know, like one percent.
• 20:38
  Speaker 2: I guess even if you're off by you know, a
• 20:40
  Speaker 2: factor of ten or even one hundred, it's still a lot,
• 20:43
  Speaker 2: Like it would be the difference between ten to the
• 20:45
  Speaker 2: forty nine truckloads or ten to the forty eight truckloads,
• 20:48
  Speaker 2: which is still a lot of truckloads. Which is a
• 20:50
  Speaker 2: truckload of truckloads.
• 20:51
  Speaker 1: It's still a lot of truckloads. Yeah, exactly. And we
• 20:54
  Speaker 1: try to be careful about what we don't know, but
• 20:56
  Speaker 1: there's always room for surprises, right. The history of physics
• 20:59
  Speaker 1: is filled with examples of times when we thought we
• 21:01
  Speaker 1: knew what we were doing and then it was all
• 21:03
  Speaker 1: blown up because we discovered something which shakes the foundations.
• 21:07
  Speaker 1: So we could certainly be wrong about it, but I'd
• 21:09
  Speaker 1: be surprised, all.
• 21:10
  Speaker 2: Right, Well, I think that's the answer for Eric. He
• 21:12
  Speaker 2: asked how many tons of mass would his truck have
• 21:14
  Speaker 2: to pull if he were to move it from Utah
• 21:17
  Speaker 2: to Idaho, and the answer is about approximately We think
• 21:20
  Speaker 2: ten to the fifty three kilograms, which is a truckload
• 21:24
  Speaker 2: of truckloads.
• 21:26
  Speaker 1: Better get some coffee.
• 21:27
  Speaker 2: Eric, and maybe put this podcast on repeat unless it
• 21:30
  Speaker 2: makes you fall asleep, in which case maybe not. All right,
• 21:33
  Speaker 2: let's get to our other questions here. There's one about
• 21:37
  Speaker 2: moons made out of gas, and also what would happen
• 21:39
  Speaker 2: if you stuck your finger in a black hole? So
• 21:42
  Speaker 2: we'll get to those, but first let's take a quick break.
• 21:57
  Speaker 5: All right.
• 21:58
  Speaker 2: We're answering questions from listeners. We just asked her a
• 22:01
  Speaker 2: great one about the mass of the entire universe, or
• 22:04
  Speaker 2: at least the observable universe. And our next question comes
• 22:07
  Speaker 2: from Tim from Virginia.
• 22:09
  Speaker 4: Hey, Daniel and Jorge. This is Tim from Virginia. I
• 22:13
  Speaker 4: was thinking recently about gas, giant planets, and moons and was.
• 22:19
  Speaker 2: Curious why all of the moons that I've.
• 22:21
  Speaker 4: Ever heard of are rocky and there are no gas
• 22:24
  Speaker 4: moons that exist?
• 22:26
  Speaker 1: Or do they?
• 22:27
  Speaker 2: Why and why not? Thanks for answering, cheers, Why and
• 22:32
  Speaker 2: why not? That's the fundamental human question. But Dad, this
• 22:36
  Speaker 2: is a great question from Tim. Thank you Tim. And
• 22:38
  Speaker 2: his question is are there moons out there, at least
• 22:41
  Speaker 2: in our Solar system that are made out of gas?
• 22:44
  Speaker 1: Yeah? A really find question because he's noticing that there's
• 22:47
  Speaker 1: like two different kinds of planets, rocky planets where you
• 22:50
  Speaker 1: can walk around on the surface, and then like gas
• 22:53
  Speaker 1: giants like Jupiter and Saturn that are being blobs mostly
• 22:57
  Speaker 1: of gas that you just like gently sink into if
• 22:59
  Speaker 1: you try to walk on. All the moons, of course,
• 23:01
  Speaker 1: seem to be rocky, and so it's a great question.
• 23:04
  Speaker 1: Are the moons made of gas? And why not?
• 23:06
  Speaker 2: Yeah? And why skip from solid to gas? Could there
• 23:08
  Speaker 2: be liquid moons out there?
• 23:12
  Speaker 1: Are you? Especially if they'sty today? You want to drink
• 23:14
  Speaker 1: a whole moon, you know, to put your straw up
• 23:16
  Speaker 1: to it and just.
• 23:16
  Speaker 2: Like shop Yeah inhil a moon, eat the moon, drink
• 23:20
  Speaker 2: a moon worm or menu options for moons.
• 23:24
  Speaker 1: I want a moon boba, right, just like floating tapioca
• 23:26
  Speaker 1: inside the moon with a huge straw.
• 23:28
  Speaker 2: Yeah, Like is it going to hit your eye like
• 23:30
  Speaker 2: a big pizza pie or you know, is it going
• 23:33
  Speaker 2: to hit your face like a big puffer air.
• 23:36
  Speaker 1: And I like this question because it makes us think
• 23:37
  Speaker 1: about like why we have gas giants in the first place,
• 23:40
  Speaker 1: Like how do you get a gas planet to form?
• 23:43
  Speaker 2: Anyway, I guess it's sort of like that's how things
• 23:45
  Speaker 2: forman space, Like if you have a big cloud of
• 23:47
  Speaker 2: gas out there, it's eventually going to collapse into a
• 23:51
  Speaker 2: gas body, right.
• 23:52
  Speaker 1: Yeah, And most of the universe are these lighter elements hydrogen, helium,
• 23:56
  Speaker 1: et cetera, which we think of as gases, and so
• 23:59
  Speaker 1: the Sun is mostly made of hydrogen, and Jupiter is
• 24:02
  Speaker 1: mostly made of hydrogen. Hydrogen dominates the whole universe, and
• 24:06
  Speaker 1: so of course it also dominates the Solar System. The
• 24:08
  Speaker 1: other fun stuff that make us up carbon and oxygen
• 24:12
  Speaker 1: and nitrogen. It's a tiny fraction of the universe and
• 24:15
  Speaker 1: also a tiny fraction of the Solar System.
• 24:17
  Speaker 2: Like the most of the regular mass of the universe
• 24:20
  Speaker 2: is what percent of hydrogen.
• 24:22
  Speaker 1: So hydrogen is like ninety one percent of the universe
• 24:25
  Speaker 1: by atoms, like if you count the number of atoms,
• 24:28
  Speaker 1: but it's only like seventy four percent of the mass
• 24:31
  Speaker 1: fraction of the universe because it's so light. So uranium,
• 24:34
  Speaker 1: for example, is many many times heavier than hydrogen. So
• 24:37
  Speaker 1: a single uranium atom outweighs hundreds of hydrogen atoms.
• 24:41
  Speaker 2: But there aren't that many uranium atoms in the universe.
• 24:44
  Speaker 1: No, there really are not very many uranium atoms, so
• 24:47
  Speaker 1: like ninety one percent of all atoms out there are
• 24:50
  Speaker 1: just hydrogen.
• 24:50
  Speaker 2: Yeah, so it's sort of a hydrogen universe. But then
• 24:53
  Speaker 2: I guess the question is can you form a moon
• 24:55
  Speaker 2: out of hydrogen or any gas?
• 24:57
  Speaker 1: Yeah, So I think to answer that question we have
• 24:59
  Speaker 1: to think about why we have also planets made out
• 25:02
  Speaker 1: of gas and some planets made out of rocks, right,
• 25:04
  Speaker 1: Like why do we have rocky planets and why do
• 25:07
  Speaker 1: we have gas planets? And as you said, everything forms
• 25:09
  Speaker 1: out of the original blob that created the Solar System,
• 25:12
  Speaker 1: a blob of gas and dust, etc. That then collapsed
• 25:15
  Speaker 1: and made the star. Not all of it falls into
• 25:18
  Speaker 1: the star, because some of it's spinning really really fast
• 25:20
  Speaker 1: and ends up in orbit, and some of that stuff
• 25:22
  Speaker 1: has enough gravity of its own to gather itself together
• 25:26
  Speaker 1: to make planets. And there's this division between the inner
• 25:29
  Speaker 1: Solar System and the outer Solar System. The inner Solar
• 25:32
  Speaker 1: System is where we get like rocky planets, and the
• 25:34
  Speaker 1: outer Solar system is where we get like gas giants,
• 25:37
  Speaker 1: and the division comes from where water is able to freeze.
• 25:41
  Speaker 1: Like in the inner Solar System, there's so much radiation
• 25:43
  Speaker 1: from the Sun that water is basically a vapor even
• 25:46
  Speaker 1: when it's out in space, but outpast what we call
• 25:49
  Speaker 1: the snow line, and you're far enough away from the Sun,
• 25:52
  Speaker 1: water can form crystals. So those crystals gather together and
• 25:55
  Speaker 1: they help build those planets. So as the Solar System
• 25:58
  Speaker 1: is forming, those water crystals help see the formation of
• 26:01
  Speaker 1: the gas giants, help them gobble up their own helping
• 26:03
  Speaker 1: of gas, which is why Jupiter got such a big scoop.
• 26:07
  Speaker 2: Of hydrogen, right, Isn't it also a little bit because
• 26:10
  Speaker 2: like any gas that was close to the Sun sort
• 26:12
  Speaker 2: of fill in right away because it's so light.
• 26:14
  Speaker 1: Yeah, there's actually two different effects there. One is you're right,
• 26:18
  Speaker 1: the Sun gobbles up a lot of gas and dust,
• 26:20
  Speaker 1: and then once it starts fusing, it blows away all
• 26:23
  Speaker 1: remaining gas and dust, like the solar wind blew away
• 26:26
  Speaker 1: the Earth's atmosphere in the early formation of the Solar system.
• 26:30
  Speaker 1: So any hydrogen in the inner Solar System either fell
• 26:32
  Speaker 1: into the Sun or got blown out by the Sun's radiation,
• 26:36
  Speaker 1: which is why we end up with only the heavier
• 26:38
  Speaker 1: stuff making planets in the Inner Solar System and in
• 26:41
  Speaker 1: the Outer Solar System, you're far enough away from the
• 26:43
  Speaker 1: Sun that you can capture some hydrogen and you have
• 26:46
  Speaker 1: the assistance of these water crystals to seed your gravitational attraction.
• 26:50
  Speaker 1: Plus you're far enough away from the Sun that its
• 26:52
  Speaker 1: radiation doesn't blow all of your hydrogen out into deep space.
• 26:56
  Speaker 2: All right, So there was sort of a big band
• 26:58
  Speaker 2: of hydrogen gas in the Outer Solar System, which is
• 27:01
  Speaker 2: where you know Jupiter and Saturn and all of those
• 27:03
  Speaker 2: gas planets came from. But I guess the question is
• 27:06
  Speaker 2: can you make a moon out of gas?
• 27:07
  Speaker 1: So in principle, you can make a moon out of gas,
• 27:10
  Speaker 1: but you probably can't keep a moon out of gas
• 27:13
  Speaker 1: because in order to hold onto gas, you have to
• 27:15
  Speaker 1: have enough mass, Like the Earth holds onto its thin
• 27:19
  Speaker 1: layer of atmosphere because of its mass. The gravity of
• 27:22
  Speaker 1: the Earth is holding the atmosphere to it. Mars, which
• 27:26
  Speaker 1: is smaller, has much less mass than a much thinner atmosphere.
• 27:30
  Speaker 1: Our moon, which is even smaller than Mars, has much
• 27:33
  Speaker 1: much less gravity and has essentially no atmosphere for that reason.
• 27:37
  Speaker 1: So you make something that's too small, even if it
• 27:40
  Speaker 1: started out with a little envelope of gas, or even
• 27:42
  Speaker 1: a lot of gas, it's just gonna lose it. It's
• 27:44
  Speaker 1: just gonna boil away into space.
• 27:47
  Speaker 2: I guess if you're like a gas molecule and you're
• 27:49
  Speaker 2: hanging out in the Moon, you could be like, oh,
• 27:52
  Speaker 2: this moon is not so attractive. I'll just fly off
• 27:54
  Speaker 2: into space. That's what you mean by boil off, right.
• 27:57
  Speaker 1: Yeah, every hydrogen molecule in the vicinity of the moon
• 28:00
  Speaker 1: and basically has escape velocity. It's not that hard to
• 28:03
  Speaker 1: escape the gravity of the Moon because the Moon doesn't
• 28:05
  Speaker 1: have that much mass. So any hydrogen atom that's out
• 28:09
  Speaker 1: there is basically hot enough it has enough speed that
• 28:11
  Speaker 1: if it's pointed in the direction of space, it'll just
• 28:13
  Speaker 1: keep going and the Moon can't hold onto it. That's
• 28:16
  Speaker 1: also partially true for the Earth, like the Earth is
• 28:19
  Speaker 1: losing some of its hydrogen. That's one reason why hydrogen
• 28:22
  Speaker 1: is a tiny fraction of our atmosphere, because it's the
• 28:25
  Speaker 1: hardest to hold onto because it's so light.
• 28:28
  Speaker 2: So now let's say what happens if I made a
• 28:31
  Speaker 2: moon out of gas. Like I just took a tag
• 28:33
  Speaker 2: of hydrogen out into space and I released it, creating
• 28:36
  Speaker 2: a cloud of hydrogen. Is that cloud gonna keep orbiting
• 28:39
  Speaker 2: around the Earth or is it just gonna disperse?
• 28:41
  Speaker 1: It depends a little bit also on the temperature. If
• 28:43
  Speaker 1: you could chill that hydrogen down and keep it cold,
• 28:47
  Speaker 1: then it might stay together. If it was kind of more,
• 28:49
  Speaker 1: if you like sprayed it out of a nozzle and
• 28:50
  Speaker 1: it's moving pretty fast, then it's just gonna disperse.
• 28:54
  Speaker 2: It be liquid. Do you mean, like if it was
• 28:55
  Speaker 2: super cold it would be liquid or would it stay
• 28:58
  Speaker 2: in gas form?
• 29:00
  Speaker 1: Sure? It is essentially zero out there, so the phases
• 29:02
  Speaker 1: get a little bit weird you think about it in
• 29:04
  Speaker 1: terms of vapor versus crystals. Really there's no like flowing liquid.
• 29:09
  Speaker 2: All right, So then could you form any moon out
• 29:11
  Speaker 2: of gas?
• 29:12
  Speaker 1: If possible, if you made it really really cold and
• 29:14
  Speaker 1: really really massive, but then basically you're making another planet.
• 29:18
  Speaker 1: That's basically what the gas giants are.
• 29:20
  Speaker 2: So like, for example, if I take the mass of
• 29:22
  Speaker 2: our moon and made it into gas, would it stay
• 29:26
  Speaker 2: as a you know, as a satellite or would that
• 29:29
  Speaker 2: just disperse?
• 29:30
  Speaker 1: It would just disperse? Yeah, there are some moons in
• 29:32
  Speaker 1: the Solar System that do have an atmosphere like Titan.
• 29:35
  Speaker 1: For example, a moon of Saturn does have an atmosphere,
• 29:38
  Speaker 1: and its atmosphere is actually a little bit thicker than
• 29:41
  Speaker 1: the Earth's atmosphere. Titan, of course, it's not a small moon.
• 29:44
  Speaker 1: It's a really massive thing. It's like ten times the
• 29:46
  Speaker 1: mass of our moon.
• 29:48
  Speaker 2: I think you're saying that there aren't any then gas
• 29:51
  Speaker 2: moons in our solar system.
• 29:52
  Speaker 1: There aren't any gas moons in our solar system. And
• 29:54
  Speaker 1: almost every moon in our solar system doesn't even have
• 29:57
  Speaker 1: an atmosphere because they don't have the mass to hold
• 29:59
  Speaker 1: it toge together. Titan is really an exception. It's the
• 30:02
  Speaker 1: only one that has enough mass to hold an atmosphere.
• 30:05
  Speaker 1: That's probably because it's really cold, and also because it's
• 30:07
  Speaker 1: around Saturn instead of Jupiter. Jupiter has more radiation to
• 30:10
  Speaker 1: blast its moons than Saturn does. If you took a huge,
• 30:14
  Speaker 1: massive blob of gas and made it really, really cold,
• 30:16
  Speaker 1: it might collapse into a gas moon, but it would
• 30:18
  Speaker 1: take very special conditions.
• 30:20
  Speaker 2: All right. It sounds like gas is just too slippery
• 30:23
  Speaker 2: to wispy to really kind of hold together unless you
• 30:26
  Speaker 2: have a lot of gravity, in which case you would
• 30:28
  Speaker 2: be a gas planet like Jupiter or Saturn.
• 30:31
  Speaker 1: Yeah, though, as we talked about recently on the podcast,
• 30:33
  Speaker 1: the distinction between a moon and a planet is a
• 30:35
  Speaker 1: little bit fuzzy. You might have, for example, a pair
• 30:38
  Speaker 1: of planets that are orbiting each other, call one a planet,
• 30:41
  Speaker 1: one a moon. In that scenario, both of them could
• 30:44
  Speaker 1: really be gas planets. The one of them, technically you
• 30:47
  Speaker 1: might call a moon of the other one and make
• 30:49
  Speaker 1: the thing big enough to be able to hold its gas.
• 30:51
  Speaker 1: It's basically a planet.
• 30:53
  Speaker 2: Like you could have a situation where like a Saturn
• 30:55
  Speaker 2: Neptune is orbiting around a Jupiter out there in another
• 30:58
  Speaker 2: solar system, in which case you would have a gas moon.
• 31:01
  Speaker 1: Yeah, although it might be like a binary planet system
• 31:04
  Speaker 1: sharing an orbit. But yeah, then it's just a question
• 31:06
  Speaker 1: of names.
• 31:07
  Speaker 2: I wonder if, technically, like our atmosphere sort of is
• 31:10
  Speaker 2: like a gas moon, right, I mean, technically all the
• 31:16
  Speaker 2: gas in our atmosphere is kind of in orbit around
• 31:19
  Speaker 2: the Earth, right, It's not stuck to the Earth technically.
• 31:22
  Speaker 1: That's an interesting question. And we did talk in that
• 31:24
  Speaker 1: episode about moons that there's no lower limit to the
• 31:27
  Speaker 1: definition of moon. It's basically any natural satellite. If you
• 31:31
  Speaker 1: go far out past the atmosphere to Earth's exosphere, you
• 31:35
  Speaker 1: have these little particles which really are in orbit around
• 31:38
  Speaker 1: the Earth. In the atmosphere, it's not really fair to
• 31:40
  Speaker 1: say it's in orbit because a lot of the forces
• 31:42
  Speaker 1: on those objects come from neighboring gas molecules. Out in
• 31:44
  Speaker 1: the exosphere where it's really collisionless, where the molecules don't
• 31:48
  Speaker 1: really talk to each other. Then yeah, you could say
• 31:50
  Speaker 1: those things are in orbit around the Earth. So each
• 31:52
  Speaker 1: one is like a particle sized moon.
• 31:55
  Speaker 2: There you go. I guess you can have a gas moon,
• 31:57
  Speaker 2: but you can have a gas sort of moon or
• 32:00
  Speaker 2: orbit around the planet.
• 32:02
  Speaker 1: Yeah, you can't have a gas giant moon, but you
• 32:04
  Speaker 1: can have a gas particle moon, I suppose.
• 32:07
  Speaker 2: All right, Well, I think that answers Tim's question. Are
• 32:10
  Speaker 2: there moons made out of gas? Not that we know of,
• 32:13
  Speaker 2: at least not here in our Solar system. There might
• 32:15
  Speaker 2: be out there binary planet systems that are made out
• 32:18
  Speaker 2: of gas, in which case you might call one of
• 32:19
  Speaker 2: them a gas moon. But also maybe there are particle
• 32:23
  Speaker 2: moons going around the Earth right now. They're just too
• 32:25
  Speaker 2: small to see, all right, let's get to our last
• 32:27
  Speaker 2: question from Stuart about what happens when you stick your
• 32:31
  Speaker 2: finger in a black hole. So we'll get to that,
• 32:34
  Speaker 2: but first stick another quick break. All right, we're answering
• 32:49
  Speaker 2: listener questions, and we've answered questions about the mass of
• 32:52
  Speaker 2: the universe and about whether moons can be made out
• 32:55
  Speaker 2: of gas. Our last question comes from Stewart from New Zealand.
• 32:58
  Speaker 5: Hey, Danieline hei here grew up in South Africa but
• 33:01
  Speaker 5: live in Auckland, New Zealan. Now big fan of the show,
• 33:04
  Speaker 5: been listening since the very beginning. I've got a bit
• 33:06
  Speaker 5: of a hypothetical that's been making my brain herd. I
• 33:09
  Speaker 5: was wondering, what if we could create a stable black hole,
• 33:12
  Speaker 5: say roughly earth mass, which I know is going to
• 33:14
  Speaker 5: be about the size of a ping pong ball, or
• 33:16
  Speaker 5: maybe a bit larger to say the size of a
• 33:17
  Speaker 5: tennis ball, but critically small enough that it's not going
• 33:20
  Speaker 5: to suck us in. And I then wondered what would
• 33:22
  Speaker 5: happen if I stuck my fingertip in and pulled my
• 33:24
  Speaker 5: finger out again. I presume my fingertip would get ripped off.
• 33:27
  Speaker 5: But then I was wondering about what forignification effects might
• 33:30
  Speaker 5: occur on my actual finger, and then also made me
• 33:34
  Speaker 5: wonder would I then see an image of my fingertip
• 33:37
  Speaker 5: on the surface of the black hole. And then also
• 33:40
  Speaker 5: if I was to come back, say a week later,
• 33:42
  Speaker 5: would I still see that image of my finger on
• 33:44
  Speaker 5: the black hole. I'm hoping you can help me out
• 33:46
  Speaker 5: with the answers, because this one's really been making my
• 33:48
  Speaker 5: brain herd love the show before to the next episode.
• 33:50
  Speaker 1: Thanks guys.
• 33:51
  Speaker 2: Awesome question or should I see? Questions from Stewart, one
• 33:55
  Speaker 2: of our og listeners from NZ New Zealand. It sounds
• 33:58
  Speaker 2: like he basically just wants to pull a prank the
• 34:00
  Speaker 2: black hole and be like, hey, black hole, pull my finger.
• 34:02
  Speaker 1: It sounds like he's really curious and if we put
• 34:05
  Speaker 1: a black hole in front of him, he would not
• 34:06
  Speaker 1: be able to resist sticking something inside.
• 34:10
  Speaker 2: Well, I'm glad he's going to do it, because I
• 34:12
  Speaker 2: definitely don't want to try with my finger. So that's
• 34:15
  Speaker 2: an interesting question. I guess he really just kind of
• 34:17
  Speaker 2: wants to know what happens to things as they go
• 34:20
  Speaker 2: into a black hole, you know, because it's so weird
• 34:23
  Speaker 2: to think about what happens in the vicinity of a
• 34:25
  Speaker 2: black hole. And I guess he's painting the scenario where
• 34:28
  Speaker 2: we somehow create a black hole with the same mass
• 34:30
  Speaker 2: as the Earth, which would be I think about the
• 34:33
  Speaker 2: size of a pigpunk ball or a small lemon, right,
• 34:36
  Speaker 2: And like, what if you had it right in front
• 34:38
  Speaker 2: of you, what did you stuck your finger in it?
• 34:39
  Speaker 2: What would happen?
• 34:40
  Speaker 1: Yeah? I love this question because it makes it immediate. Right,
• 34:43
  Speaker 1: black holes seem weird and mysterious and out in deep space.
• 34:46
  Speaker 1: That makes you want to like explore it concretely, like
• 34:49
  Speaker 1: have one in front of you and poke it and
• 34:50
  Speaker 1: prod it. And you know, that's what physics labs are
• 34:53
  Speaker 1: all about, and that's why we are trying to make
• 34:55
  Speaker 1: black holes the large Hatreron Collider so we can do
• 34:58
  Speaker 1: these kinds of experiments I mean with Stuart's fingertips. But yeah,
• 35:02
  Speaker 1: we want to play with black holes.
• 35:03
  Speaker 2: It sounds like you're playing with everybody's fingers by making
• 35:07
  Speaker 2: black holes here on Earth? Have you asked everyone's permission
• 35:10
  Speaker 2: to pull their fingers? But yeah, I guess it's an
• 35:12
  Speaker 2: interesting scenario because you know, we are used to thinking
• 35:14
  Speaker 2: about black holes as being humongous, right, I mean the
• 35:17
  Speaker 2: one at the center of our galaxy is many millions
• 35:19
  Speaker 2: of times bigger than our sun or heavier than our sun,
• 35:23
  Speaker 2: And so you imagine that if you're right next to
• 35:25
  Speaker 2: a black hole, it just looks like a gigantic thing
• 35:27
  Speaker 2: that covers your entire field of vision. But maybe if
• 35:31
  Speaker 2: it's small, like about the size of a lemon or
• 35:34
  Speaker 2: a penguin ball, maybe it'd be small enough to like
• 35:36
  Speaker 2: do little experiments on it, like stick your finger in it.
• 35:38
  Speaker 1: Yeah, you're right. The black holes are not about enormous
• 35:41
  Speaker 1: amounts of mass. They're really about the density of mass.
• 35:45
  Speaker 1: So you could take almost anything and if you squeeze
• 35:47
  Speaker 1: it down enough into a small enough radius, high enough density,
• 35:52
  Speaker 1: then you'll form an event horizon. The calculation is called
• 35:54
  Speaker 1: the short Stiles radius. It tells you the radius of
• 35:57
  Speaker 1: the event horizon for a given mass, so's long as
• 36:00
  Speaker 1: you get all the mass of something within that radius,
• 36:03
  Speaker 1: then it becomes a black hole. You get an event horizon.
• 36:06
  Speaker 1: And if you plug the numbers in for the Earth,
• 36:08
  Speaker 1: then the radius of that event horizon is just under
• 36:11
  Speaker 1: one centimeter. So if you were able to take the
• 36:13
  Speaker 1: Earth and somehow squeeze it down to something with the
• 36:16
  Speaker 1: radius of a centimeter, it would have an event horizon.
• 36:19
  Speaker 1: All that mass inside of it would have so much
• 36:21
  Speaker 1: gravity that it would bend space and create that threshold.
• 36:25
  Speaker 2: So if you could do that, you would have a
• 36:27
  Speaker 2: black hole possibly in front of you, right like on
• 36:30
  Speaker 2: your desktop.
• 36:30
  Speaker 1: You would have a black hole in front of you.
• 36:32
  Speaker 1: Though it would be very, very powerful. There's a couple
• 36:35
  Speaker 1: confusing things going on here. On one hand, Stewart's on
• 36:38
  Speaker 1: the right track that if you can pack the Earth
• 36:39
  Speaker 1: into a black hole, you're not fundamentally changing the amount
• 36:42
  Speaker 1: of mass that's there. You're just squeezing it down. So
• 36:44
  Speaker 1: if you stay at the same distance you were before,
• 36:47
  Speaker 1: you're still going to feel the same amount of gravity.
• 36:49
  Speaker 1: He's imagining that an earth mass black hole is not
• 36:52
  Speaker 1: going to be that powerful because the Earth's gravity doesn't
• 36:55
  Speaker 1: feel that powerful. I mean, I'm standing on the Earth's
• 36:57
  Speaker 1: surface that can jump and avoid it, right, But that's
• 36:59
  Speaker 1: because I'm pretty far away from the center of mass
• 37:02
  Speaker 1: of the Earth. If I formed an earth mass black
• 37:05
  Speaker 1: hole and then got really really close to it, like
• 37:08
  Speaker 1: a centimeter, two centimeters, even a meter, its gravity would
• 37:11
  Speaker 1: be much more powerful than the gravity we feel here
• 37:14
  Speaker 1: on the surface of the Earth. Because I'd be much
• 37:16
  Speaker 1: much closer.
• 37:17
  Speaker 2: Right, Like, if I made a black hole like that,
• 37:19
  Speaker 2: I would the same mass as to Earth, and i
• 37:21
  Speaker 2: put it in the center of the Earth, and I'm
• 37:23
  Speaker 2: standing about an earth radius away from it, i would
• 37:26
  Speaker 2: feel the same gravity that I'm feeling right now, which
• 37:29
  Speaker 2: is doesn't seem like a lot. But I'm pretty far
• 37:31
  Speaker 2: away from the black hole, right It's like ten thousand
• 37:35
  Speaker 2: miles or something like that.
• 37:36
  Speaker 1: You're pretty far from the center of mass of the Earth.
• 37:38
  Speaker 1: If instead you compacted all that mass into one centimeter
• 37:42
  Speaker 1: and then you stood right next to it, then you'd
• 37:44
  Speaker 1: be seven hundred million times closer to the center of
• 37:48
  Speaker 1: mass than you are in the surface of the Earth.
• 37:51
  Speaker 1: And because gravity gets stronger with distance squared, like twice
• 37:55
  Speaker 1: as close means four times as strong, then the gravity
• 37:58
  Speaker 1: of the earth mass black hole, if you're one centimeter
• 38:02
  Speaker 1: away from it, would be quadrillions of times more powerful
• 38:05
  Speaker 1: than Earth's gravity.
• 38:06
  Speaker 2: Right, it would be like five times ten to the
• 38:08
  Speaker 2: seventeen right five with seventeen zeros basically.
• 38:12
  Speaker 1: G exactly, so it would gobble Steward up. There wouldn't
• 38:16
  Speaker 1: be like time to think about which finger to stick
• 38:18
  Speaker 1: into it. It's to be incredibly powerful gravity you would
• 38:22
  Speaker 1: slurp him up in a moment.
• 38:23
  Speaker 2: Yeah, I think you're saying, if you're close enough to
• 38:24
  Speaker 2: touch it, that means you're at arm's length from it, Yes,
• 38:27
  Speaker 2: in which case the gravity would be super duper strong,
• 38:30
  Speaker 2: but maybe more important, the tidle forces would be shredding
• 38:33
  Speaker 2: you apart exactly.
• 38:35
  Speaker 1: The title forces come from the variation of gravity across distance.
• 38:40
  Speaker 1: If you're a point mass, you don't feel any title forces.
• 38:42
  Speaker 1: You just feel gravity. But if you're larger, so that
• 38:45
  Speaker 1: parts of you are closer to the black hole and
• 38:47
  Speaker 1: parts of you are further away, then they're feeling different
• 38:49
  Speaker 1: amounts of gravity. And basically the black hole is tugging
• 38:52
  Speaker 1: you apart because it's pulling on different parts of you
• 38:55
  Speaker 1: with different strengths.
• 38:56
  Speaker 2: Right, Like that happens right now as you're sitting there
• 38:58
  Speaker 2: or standing there on the surface, so the Earth your
• 39:00
  Speaker 2: feet are getting pulled more than your head.
• 39:03
  Speaker 1: Yeah, your feet are getting pulled more than your head.
• 39:05
  Speaker 1: So your Earth is trying to pull your head off
• 39:07
  Speaker 1: of your body. And as you get closer to the
• 39:10
  Speaker 1: black hole, the difference in those two forces grows, and
• 39:13
  Speaker 1: so the effective force the Earth trying to decapitate. You
• 39:16
  Speaker 1: also grows, and eventually it overcomes your body's ability to
• 39:20
  Speaker 1: keep your head on your shoulders.
• 39:22
  Speaker 2: So like, if you were maybe a meter from a
• 39:24
  Speaker 2: small black hole like that and you raise your arm
• 39:27
  Speaker 2: to point your finger towards it, your finger would suddenly
• 39:30
  Speaker 2: feel a huge amount more force than the rest of
• 39:32
  Speaker 2: your body. So basically it would pull your finger, right,
• 39:35
  Speaker 2: it will shred pull your finger out of your body.
• 39:38
  Speaker 1: Yeah, you can calculate the safe distance with which you
• 39:41
  Speaker 1: can approach a black hole, and it depends on the
• 39:44
  Speaker 1: mass of the black hole, of course, because the tile
• 39:46
  Speaker 1: forces go by like the derivative of the gravitational force,
• 39:50
  Speaker 1: and for an earth mass black hole, it's between one
• 39:53
  Speaker 1: and ten thousand kilometers. So you can't get very close
• 39:56
  Speaker 1: to an earth mass black hole without its charading you apart.
• 40:00
  Speaker 2: Oh, so you'd have to be pretty much as far
• 40:03
  Speaker 2: away from it as we are from the center of
• 40:05
  Speaker 2: the Earth right now, For.
• 40:06
  Speaker 1: An earth mass black hole, you need to still stay
• 40:08
  Speaker 1: at least a thousand kilometers away from the edge of
• 40:11
  Speaker 1: the black hole to avoid being pulled apart.
• 40:14
  Speaker 2: So basically you can't stick your finger inside of that black.
• 40:17
  Speaker 1: Hole and less your thanos and you have like more
• 40:21
  Speaker 1: body integrity and ability to resist the tidal forces somehow.
• 40:25
  Speaker 1: Then yeah, you can never even get close enough to
• 40:27
  Speaker 1: stick your finger in.
• 40:28
  Speaker 2: Well, I guess you could. I mean you'd raise your hand,
• 40:31
  Speaker 2: the bung hole will rip your arm out, your finger out,
• 40:35
  Speaker 2: and then technically it would get sucked in and you'd
• 40:38
  Speaker 2: be sort of sticking your finger in, but you wouldn't
• 40:40
  Speaker 2: be attached to that finger.
• 40:42
  Speaker 1: Yeah, and your finger would be a long string of
• 40:44
  Speaker 1: particles pulled into spaghetti by the tidal forces before it
• 40:47
  Speaker 1: even got to the black hole.
• 40:49
  Speaker 2: But I think maybe Stuart's question was, like, you know,
• 40:51
  Speaker 2: let's say that you made a black hole, maybe with
• 40:54
  Speaker 2: smaller or maybe you're somehow able to create a stick
• 40:57
  Speaker 2: that is strong enough to hold together that you can
• 41:00
  Speaker 2: poke into a black hole. I think he's asking what
• 41:03
  Speaker 2: would you see? What would happen? Because I know we've
• 41:05
  Speaker 2: talked about like around a black hole, time freezes to stop. Right.
• 41:10
  Speaker 1: Yeah, when space gets curved, it time goes slow. So
• 41:13
  Speaker 1: things that fall into a black hole for an outside observer,
• 41:17
  Speaker 1: their time goes slower. So if you drop a clock
• 41:20
  Speaker 1: into a black hole and then you watch it with
• 41:22
  Speaker 1: a telescope, you'll see that the time on that clock
• 41:24
  Speaker 1: will tick slower than the clock that you are holding.
• 41:27
  Speaker 1: That also controls how quickly it falls into a black hole.
• 41:31
  Speaker 1: So as things approach the event horizon, their time gets
• 41:33
  Speaker 1: slower and slower, and they get more and more smeared out. Also,
• 41:37
  Speaker 1: they get red shifted by that curvature, so things get
• 41:41
  Speaker 1: slowed down and smeared out into the red pininy.
• 41:44
  Speaker 2: I guess if you take this stick that you're going
• 41:46
  Speaker 2: to stick into the black hole, you put an indestructible
• 41:48
  Speaker 2: watch at the end of it, and then you use
• 41:51
  Speaker 2: that to poke the black hole, you would see it.
• 41:54
  Speaker 2: I guess you would see it approach the black hole
• 41:56
  Speaker 2: the event horizon. You would see that the takes in
• 41:59
  Speaker 2: the clocks aren't going slower, taking slower. And then would
• 42:02
  Speaker 2: you actually see that the rod the event horizon if
• 42:07
  Speaker 2: you keep pushing it towards it.
• 42:08
  Speaker 1: So this is a little bit tricky and a common
• 42:10
  Speaker 1: source of misunderstanding. People often say you can never see
• 42:13
  Speaker 1: anything enter a black hole because time slows down and
• 42:16
  Speaker 1: you have to wait till the end of the universe
• 42:18
  Speaker 1: to see something actually fall into the black hole. That's true.
• 42:21
  Speaker 1: If you just drop like a particle into a black hole,
• 42:23
  Speaker 1: it'll take forever for it to actually fall in. But
• 42:26
  Speaker 1: what's happening as it falls in is that the event
• 42:28
  Speaker 1: horizon is already growing, like as it approaches the black hole,
• 42:32
  Speaker 1: it contributes its gravitational energy to the mass of the
• 42:35
  Speaker 1: black hole. So the event horizon is actually growing out
• 42:38
  Speaker 1: to meet it. It's not like it has to pass
• 42:40
  Speaker 1: over the event horizon to contribute to the black hole.
• 42:43
  Speaker 1: The two approach each other very slowly. What that means
• 42:46
  Speaker 1: is if you then throw something else in, like a
• 42:48
  Speaker 1: second particle, that second particle will pull the event horizon
• 42:51
  Speaker 1: out even further and you will see the first one absorbed.
• 42:54
  Speaker 1: So it's true that if you drop a single particle
• 42:56
  Speaker 1: and then nothing else into a black hole, it will
• 42:59
  Speaker 1: never enter the event horizon. But if you use a stick,
• 43:02
  Speaker 1: which is like a long string of particles, then the
• 43:04
  Speaker 1: next particle pulls the event horizon over the previous one,
• 43:06
  Speaker 1: et cetera, et cetera, so you actually would see the
• 43:09
  Speaker 1: tip enter the black hole.
• 43:10
  Speaker 2: All right, well, maybe let's do it play by place.
• 43:12
  Speaker 2: I have this long indestructible stick with a watch at
• 43:15
  Speaker 2: the end of it. I pointed towards the black hole.
• 43:17
  Speaker 2: I poke the black hole, and I stop at the
• 43:20
  Speaker 2: moment the tip touches the black hole. It's at the
• 43:23
  Speaker 2: edge of the black hole, and I push it in
• 43:25
  Speaker 2: an inch. Are you saying that that that inch of
• 43:27
  Speaker 2: indestructible rod that I push it into this black hole
• 43:32
  Speaker 2: is enough to grow the event horizon an inch?
• 43:36
  Speaker 1: The mount of the event horizon grows depends on the
• 43:38
  Speaker 1: mass of the thing that you're putting into it, So
• 43:40
  Speaker 1: it depends if this rod is made out of like
• 43:42
  Speaker 1: lead or titanium or hydrogen or whatever. But just because
• 43:46
  Speaker 1: you put an inch worth of rod doesn't mean the
• 43:48
  Speaker 1: event horizon grows an inch.
• 43:50
  Speaker 2: So then let's say it's not right. Then if I
• 43:53
  Speaker 2: push it an inch into the black hole, am I
• 43:56
  Speaker 2: going to see it go into the black hole?
• 43:57
  Speaker 1: Then you are because you're pushing it in, right, You're
• 43:59
  Speaker 1: not just waiting for the event horizon to grow out
• 44:02
  Speaker 1: to gobble it. You're pushing it in. When I say
• 44:04
  Speaker 1: the event horizon is growing out. This just to help
• 44:06
  Speaker 1: people understand how something can actually fall into the event horizon.
• 44:10
  Speaker 1: When an object falls into the event horizon, it's because
• 44:12
  Speaker 1: the next thing falling in has pulled the event horizon
• 44:15
  Speaker 1: out over it.
• 44:16
  Speaker 2: M right, Okay, So then maybe let's not think about
• 44:20
  Speaker 2: that scenario. Let's think about the one Steward is thinking about,
• 44:23
  Speaker 2: which is sticking your finger into the black hole. See
• 44:25
  Speaker 2: if I stick this metal finger into the black hole,
• 44:28
  Speaker 2: I would see it going.
• 44:29
  Speaker 1: You would see it go in time would slow down
• 44:30
  Speaker 1: and it would get red shifted still right, Your finger
• 44:33
  Speaker 1: would get redder and redder and darker and darker and
• 44:35
  Speaker 1: then eventually invisible right in black. But you would see
• 44:39
  Speaker 1: it going. You would have your finger sticking out of
• 44:41
  Speaker 1: a black hole.
• 44:42
  Speaker 2: It would hurt, or at least the back part of
• 44:44
  Speaker 2: your metal indestructible finger is sticking out of the black hole.
• 44:47
  Speaker 2: Now what if I pull it?
• 44:47
  Speaker 1: Then you're going to have a finger tipless finger?
• 44:51
  Speaker 2: You mean I lost my watch? Yeah? Exactly could you
• 44:54
  Speaker 2: pull it?
• 44:55
  Speaker 5: I guess?
• 44:55
  Speaker 2: I guess, yeah, I guess could you? It'd be hard,
• 44:58
  Speaker 2: but you could, right, I guess.
• 45:00
  Speaker 1: Yeah. If we're talking about a really small black hole,
• 45:02
  Speaker 1: one that you could stand next to safely, then it
• 45:04
  Speaker 1: actually wouldn't have that much gravity. Like if you take
• 45:07
  Speaker 1: the Empire States building and you squeeze it down into
• 45:10
  Speaker 1: a black hole, it's going to have as much gravity
• 45:12
  Speaker 1: as the Empire States building, and that's not that much, right,
• 45:14
  Speaker 1: You can stand next to the mPire States building without
• 45:17
  Speaker 1: like leaning over because if it's gravity, because remember gravity
• 45:20
  Speaker 1: is super duper weak, so even something as big as
• 45:22
  Speaker 1: a building doesn't have that much gravity.
• 45:25
  Speaker 2: Well, but then gravity increases the closer you get to it,
• 45:27
  Speaker 2: so maybe it would still shredd you if you got
• 45:29
  Speaker 2: you know, within an inch of it.
• 45:30
  Speaker 1: Maybe mm hmm. You can get closer to a building
• 45:33
  Speaker 1: mass black hole than you can actually to the center
• 45:35
  Speaker 1: of mass of a building.
• 45:36
  Speaker 2: Absolutely, So then if I stick a metal finger into it,
• 45:40
  Speaker 2: I would see it go in. I could pulk the
• 45:42
  Speaker 2: black hole. But then when I pulled my finger, it
• 45:44
  Speaker 2: will have eaten whatever was inside of the event horizon.
• 45:47
  Speaker 1: And the last things in there would be smeared across
• 45:50
  Speaker 1: the surface of the event horizon because the last thing
• 45:52
  Speaker 1: you tried to stick in would take forever to actually
• 45:55
  Speaker 1: fall in until something else comes along and it pulls
• 45:58
  Speaker 1: out the event horizon over it all?
• 46:00
  Speaker 2: Right, Well, I think that answers Stuart's question. Don't stick
• 46:03
  Speaker 2: your finger in a black hole.
• 46:04
  Speaker 1: Don't stick your finger in a black hole, Stewart, This
• 46:07
  Speaker 1: is not medical advice, but it's physics advice.
• 46:09
  Speaker 2: Well, I wonder if like the black hole is so little,
• 46:12
  Speaker 2: like like you said, with the mass of the empire
• 46:14
  Speaker 2: state building, I imagine it would be you know, super
• 46:16
  Speaker 2: duper tiny small, right, like micron small?
• 46:20
  Speaker 5: Right?
• 46:20
  Speaker 1: Yeah. Absolutely, The masses of the black holes we try
• 46:22
  Speaker 1: to make the large Hadron collider are even tinier, and
• 46:25
  Speaker 1: their event horizons are really really small. Yeah, we're talking microscopic.
• 46:30
  Speaker 2: What happens if you stick your fingers in those, you'll
• 46:32
  Speaker 2: make a hole in your finger.
• 46:33
  Speaker 1: Yeah, I suppose it'd be like a laser beam. But
• 46:35
  Speaker 1: there's another effect there which is really really microscopic. Black
• 46:38
  Speaker 1: holes don't last very long. So if you make a
• 46:40
  Speaker 1: black hole that's really really small, it'll hawking radiation away
• 46:44
  Speaker 1: its mass really really fast, because the rate of hawking
• 46:47
  Speaker 1: radiation depends on the temperature, which is inversely proportional to
• 46:51
  Speaker 1: the mass, So really small black holes are hotter and
• 46:54
  Speaker 1: have more hawking radiation, so they actually don't last very long.
• 46:58
  Speaker 2: So you'd have to have a fast finger. You have
• 47:00
  Speaker 2: to be pretty quick pok it before it evaporates.
• 47:03
  Speaker 1: You'd have to be determined to hurt yourself.
• 47:05
  Speaker 2: All right, Well, I think that answers Stuart's question. It's
• 47:08
  Speaker 2: sort of It's not necessarily the case that you would
• 47:11
  Speaker 2: never see what happens. You would see what happens if
• 47:14
  Speaker 2: you start something into a black hole.
• 47:15
  Speaker 1: That's right. If you manage to somehow s arrive getting
• 47:17
  Speaker 1: next to a black hole, you can actually stick stuff
• 47:20
  Speaker 1: into it and lose.
• 47:21
  Speaker 2: It, and then the joke would be on the black hole.
• 47:24
  Speaker 2: You can make the fart sound if you like, but
• 47:26
  Speaker 2: I guess the black hole keeps your fingers, so then
• 47:28
  Speaker 2: the joke's on.
• 47:29
  Speaker 5: You.
• 47:29
  Speaker 1: Don't try this at home, folks, but.
• 47:31
  Speaker 2: Do try it in a large particle collider. I don't
• 47:34
  Speaker 2: understand the message here.
• 47:35
  Speaker 1: Well, if those black holes are actually made, they would
• 47:37
  Speaker 1: evaporate very, very rapidly because they're super duber tiny.
• 47:41
  Speaker 2: Just don't let Stuart near them because he might want
• 47:43
  Speaker 2: us stick his fingers quickly before they evaporate. All right, Well,
• 47:46
  Speaker 2: those are three awesome questions. Thanks again to our listeners
• 47:49
  Speaker 2: for sending us these amazing questions.
• 47:51
  Speaker 1: Thank you everybody out there for being curious and wondering
• 47:54
  Speaker 1: about the nature of the world, which is the reason
• 47:55
  Speaker 1: why we get to do science and think about how
• 47:58
  Speaker 1: the universe works. You have a question about how something works,
• 48:01
  Speaker 1: Please don't be shy. Send it to us to questions
• 48:04
  Speaker 1: at danielanjorgey dot com.
• 48:05
  Speaker 2: Yeah, as you sit out there in the long call
• 48:08
  Speaker 2: of life wondering about the universe, staring out at the sky,
• 48:10
  Speaker 2: wondering what you can stick your finger in, just remember
• 48:13
  Speaker 2: it's an amazing.
• 48:14
  Speaker 1: Universe and dip your French fries into shakes, not into
• 48:17
  Speaker 1: black holes.
• 48:17
  Speaker 2: Oh what would happen then? Would they still be French?
• 48:20
  Speaker 1: They wouldn't be crunchy.
• 48:21
  Speaker 2: It would be decapitated, beheaded like in the French Revolution.
• 48:27
  Speaker 2: All right, Well, we hope you enjoyed that. Thanks for
• 48:29
  Speaker 2: joining us, See you next time.
• 48:39
  Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
• 48:42
  Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
• 48:46
  Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
• 48:51
  Speaker 1: you listen to your favorite shows.