Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 56: Neutron Stars, Dense matter and shared atmospheres!

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Listener Questions 56: Neutron Stars, Dense matter and shared atmospheres! · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, or hey, I got a question for you that
• 0:11
  Speaker 1: connects our two favorite things.
• 0:13
  Speaker 2: Ooh, is it about sleeping or taking a nap?
• 0:17
  Speaker 1: No, it's about physics and food.
• 0:20
  Speaker 2: H you mean are other two favorite things? All right?
• 0:22
  Speaker 2: What's the question?
• 0:23
  Speaker 1: Question? Is what astronomical object out there in the universe
• 0:28
  Speaker 1: would you most want to taste like?
• 0:31
  Speaker 2: Would I prefer to take a bite out of a
• 0:32
  Speaker 2: black hole or a yellow star?
• 0:35
  Speaker 1: Exactly? Chocolate versus banana?
• 0:37
  Speaker 2: Wait? A black holes made out of chocolate? Is that
• 0:39
  Speaker 2: what you're saying.
• 0:40
  Speaker 1: That's what we're trying to find out.
• 0:42
  Speaker 2: I see you're the mastermind in this evil scheme or
• 0:45
  Speaker 2: tasty scheme, one of the two. I guess in either case,
• 0:48
  Speaker 2: I'd rather just take a nap.
• 1:05
  Speaker 3: Hi.
• 1:05
  Speaker 2: I'm horim my cartoonists and the author of Oliver's Great
• 1:08
  Speaker 2: Big Universe.
• 1:08
  Speaker 1: Hi, I'm Daniel. I'm a particle physicist and a professor
• 1:11
  Speaker 1: at UC Irvine, and I do want to know what
• 1:14
  Speaker 1: a black hole tastes like?
• 1:15
  Speaker 2: Isn't that sort of a strange question to ask what
• 1:17
  Speaker 2: a whole tastes like? When did did you just leave
• 1:19
  Speaker 2: you with an empty stomach?
• 1:20
  Speaker 1: Maybe it actually be kind of a great diet you know, like,
• 1:23
  Speaker 1: take a bite of a black hole. It's like negative bites.
• 1:26
  Speaker 2: Oh, I see, we just suck out your ords and
• 1:29
  Speaker 2: you would weigh less. Yeah that works. I mean I
• 1:32
  Speaker 2: think that's all the rage in Hollywood.
• 1:33
  Speaker 1: Now this is the physics ozembic exactly.
• 1:38
  Speaker 2: Yeah. Well, I mean it's a philosophical question, like what
• 1:40
  Speaker 2: does nothingness taste like?
• 1:42
  Speaker 1: But a black hole isn't even nothing, right, it's super
• 1:44
  Speaker 1: dense something.
• 1:45
  Speaker 2: Well, there's things in the black hole, I guess, But
• 1:48
  Speaker 2: is in most of a black hole nothingness or I guess?
• 1:51
  Speaker 2: We don't know.
• 1:51
  Speaker 1: We don't know.
• 1:52
  Speaker 2: That's the point.
• 1:52
  Speaker 1: That's the deepest question in modern physics, which I want
• 1:55
  Speaker 1: you to take a bite out of.
• 1:56
  Speaker 2: You mean, the biggest question in modern physics. This is
• 1:58
  Speaker 2: what the black holes take?
• 2:00
  Speaker 1: Yeah, exactly.
• 2:02
  Speaker 2: But then here's the problem. If you do get this data,
• 2:05
  Speaker 2: isn't it very subjective? Though? It's not really objective data,
• 2:08
  Speaker 2: is it?
• 2:09
  Speaker 1: It's still data?
• 2:09
  Speaker 2: Like I might be like, hey, it's delicious, but then
• 2:12
  Speaker 2: you know, other people might disagree.
• 2:14
  Speaker 1: It's still data. We still want to know what's inside
• 2:16
  Speaker 1: a black hole. It's like when you look at an
• 2:18
  Speaker 1: amazing chocolate cake, it looks like chocolate on the outside,
• 2:21
  Speaker 1: But what if it's secretly vanilla on the inside. The
• 2:23
  Speaker 1: only way to know is to take a bite. So
• 2:25
  Speaker 1: we want to learn about what's inside a black hole,
• 2:27
  Speaker 1: maybe we just have to take a bite.
• 2:30
  Speaker 2: But I guess what I'm saying is like having a
• 2:31
  Speaker 2: person take a bite wouldn't really tell you what's inside.
• 2:34
  Speaker 2: What if it's something I've never tasted.
• 2:36
  Speaker 1: Before, But what if it's just vanilla?
• 2:38
  Speaker 2: That would be the most boring result there, like literally,
• 2:43
  Speaker 2: but anyways, welcome to our podcast, Daniel and Jorge Explain
• 2:45
  Speaker 2: the Universe, a production of iHeartRadio.
• 2:48
  Speaker 1: In which we encourage you to take a big, juicy
• 2:51
  Speaker 1: bite out of the universe. We hope the universe tastes
• 2:54
  Speaker 1: better than just vanilla. We hope that it's filled with
• 2:56
  Speaker 1: all sorts of weird stuff we never anticipated, things we've
• 2:59
  Speaker 1: never encountered before. That's just the way reality rolls. It's
• 3:03
  Speaker 1: filled with all sorts of amazing things for us to discover,
• 3:06
  Speaker 1: to understand, and to explain to you.
• 3:08
  Speaker 2: That's right. It is a tasty universe, full of interesting
• 3:11
  Speaker 2: and fascinating flavors and sometimes a lot of mysterious flavors.
• 3:15
  Speaker 2: Flavors that make you want to go, Uh, what is
• 3:18
  Speaker 2: this that I'm eating? What is it that I'm smelling?
• 3:20
  Speaker 2: What is this made out of?
• 3:21
  Speaker 1: And we know that listeners to the podcast are the
• 3:23
  Speaker 1: ones who are curious about the nature of the universe.
• 3:26
  Speaker 1: You listen because you have a deep itch to understand
• 3:29
  Speaker 1: how the universe works, and we want to reach out
• 3:32
  Speaker 1: and scratch that itch for you. And that same mitch
• 3:34
  Speaker 1: will lead you to ask questions about how everything works.
• 3:37
  Speaker 1: When ideas don't fit together in your mind, or when
• 3:40
  Speaker 1: you read something that just doesn't make sense to you,
• 3:42
  Speaker 1: you wonder, how does this all work? Is it possible
• 3:44
  Speaker 1: to understand xyz? And we encourage you to reach out
• 3:47
  Speaker 1: to us with your questions to questions At Danielandhorge dot
• 3:51
  Speaker 1: com we write back to everybody that's ray.
• 3:53
  Speaker 2: You can send in your questions and sometimes we'll pick
• 3:55
  Speaker 2: those questions to answer on the podcast or at least
• 3:58
  Speaker 2: talk about the question. Sometimes would you talk about the
• 4:00
  Speaker 2: questions without getting to an answer.
• 4:02
  Speaker 1: Well, sometimes we give an answer and you say that's
• 4:04
  Speaker 1: not really an answer, that's just a description, and then
• 4:06
  Speaker 1: we get into the philosophy.
• 4:10
  Speaker 2: I guess in either case, it's an answer technically.
• 4:14
  Speaker 1: Depends on what really is an answer anyway, man, there's
• 4:17
  Speaker 1: a deep question in philosophy.
• 4:19
  Speaker 2: But in either case, we talk about questions.
• 4:22
  Speaker 1: We do. We play your questions, we talk about them.
• 4:24
  Speaker 1: We hope to give you as much of an answer
• 4:27
  Speaker 1: as we can. Not every question in science has an answer,
• 4:30
  Speaker 1: but we want to take you at least to the
• 4:31
  Speaker 1: forefront of human understanding and ignorance so you can share
• 4:35
  Speaker 1: in our confusion.
• 4:36
  Speaker 2: Yeah, and sometimes the answer is choco lily smooth, and
• 4:39
  Speaker 2: sometimes the answer is a little spicy, little piquant.
• 4:43
  Speaker 1: Either way, we love hearing your questions, we love answering them,
• 4:46
  Speaker 1: we love talking about them. Please do keep sending them in.
• 4:49
  Speaker 2: And also, I should say I'm a little offended at
• 4:50
  Speaker 2: your negative comments about vanilla. It is one of my
• 4:53
  Speaker 2: favorite flavor.
• 4:54
  Speaker 1: You're the one who said that would be the most
• 4:55
  Speaker 1: boring outcome to a black hole. I didn't say vanilla
• 4:58
  Speaker 1: was boring.
• 5:01
  Speaker 2: Well, what I mean is like, if the flavor of
• 5:03
  Speaker 2: something as complex and mysterious as a black hole, it
• 5:06
  Speaker 2: just came down to one flavor. I mean, I think
• 5:09
  Speaker 2: vanilla would be the best case scenario, but it's not
• 5:14
  Speaker 2: the most complex as so you could.
• 5:16
  Speaker 1: Get it'd be pretty fascinating though. If black holes tasted familiar,
• 5:19
  Speaker 1: you took a bite of a black hole, you're like, hmm,
• 5:21
  Speaker 1: tastes like pineapple, that would be very surprising.
• 5:24
  Speaker 2: Let's break this down, Daniel, how would you even taste
• 5:26
  Speaker 2: a black hole because you can't take a scoop of
• 5:27
  Speaker 2: it out of the black hole, right, it's the whole
• 5:29
  Speaker 2: point of a black hole. Well, you'd have to go
• 5:31
  Speaker 2: It's the only way to taste a black hole, is, Yeah,
• 5:33
  Speaker 2: is to go inside of a black hole. That's the
• 5:34
  Speaker 2: only way to sample what's inside of a black hole. Yeah,
• 5:37
  Speaker 2: But then you could never get out. You can never
• 5:39
  Speaker 2: even if you find out what it tastes like, you
• 5:41
  Speaker 2: could never tell anyone unless the other person is there
• 5:44
  Speaker 2: with you.
• 5:44
  Speaker 1: You could take a bite of a cosmic pineapple. Maybe
• 5:47
  Speaker 1: singularities taste like cherries, who knows, But yeah, you'd have
• 5:50
  Speaker 1: to be inside the black hole to even take that bite, and.
• 5:54
  Speaker 2: You could only tell people who are in the black
• 5:56
  Speaker 2: hole with you.
• 5:56
  Speaker 1: Right, the first real black hole club is you don't
• 5:59
  Speaker 1: talk about black hole.
• 6:00
  Speaker 2: No, you could, but then only people in the club
• 6:03
  Speaker 2: can find out.
• 6:03
  Speaker 1: Yeah, that's right, very secret.
• 6:05
  Speaker 2: There's like a warmhole in the middle. I guess you
• 6:07
  Speaker 2: could yes, transmit that information, or.
• 6:10
  Speaker 1: If it's possible to encode the information in the pattern
• 6:12
  Speaker 1: of hawking radiation, like some theories of quantum gravity suggest,
• 6:15
  Speaker 1: then maybe you could tell everybody else what black holes
• 6:17
  Speaker 1: taste like.
• 6:18
  Speaker 2: Oh so wait, the first rule of a black hole
• 6:20
  Speaker 2: is not that you can't ever get out of the
• 6:22
  Speaker 2: black hole.
• 6:22
  Speaker 1: You already broke the rules quantum mechanics. Less you break
• 6:25
  Speaker 1: all sorts of rules. Man, it's wonderful. But anyway, we're
• 6:27
  Speaker 1: here to answer other people's questions, not talk about the
• 6:29
  Speaker 1: flavor of black holes.
• 6:32
  Speaker 2: I don't know. I imagine this is a question for a
• 6:33
  Speaker 2: lot of people. I mean, you brought it up.
• 6:35
  Speaker 1: I did, Yes, I did bring it up.
• 6:37
  Speaker 2: You're curious about it.
• 6:38
  Speaker 1: But I'm still not taking about that black hole. I'm
• 6:40
  Speaker 1: sending you up.
• 6:41
  Speaker 2: Maybe I'll take more of it like a slurp. That's
• 6:43
  Speaker 2: these more cautious.
• 6:44
  Speaker 1: Well, I was inspired to think about tasting things by
• 6:47
  Speaker 1: the phrasing of our first question.
• 6:49
  Speaker 2: Yes, that's right, because today on the podcast we'll be
• 6:51
  Speaker 2: tackling listener questions. Number fifty six Taste Edition. Is this
• 7:00
  Speaker 2: the extra Spicy Edition, Extra Heavy Meal Edition? These are
• 7:04
  Speaker 2: pretty heavy questions. We have a question here about a
• 7:07
  Speaker 2: neutron star, about gravitational pressure, and about orbital dynamics. These
• 7:13
  Speaker 2: are not light subjects you would have these appetizers.
• 7:16
  Speaker 1: Know this is all heavy duty stuff.
• 7:19
  Speaker 2: This is main course material here. Yeah, we like to
• 7:23
  Speaker 2: answer questions here from our listeners, and so let's get
• 7:26
  Speaker 2: down to our first question, and this one is from
• 7:29
  Speaker 2: Drew Hi Daniel Jorge.
• 7:30
  Speaker 3: I was listening to some of the older episodes and
• 7:33
  Speaker 3: neutron stars kept coming up, and it seems like we
• 7:36
  Speaker 3: always talk about a tablespoon or teaspoon of a neutron
• 7:39
  Speaker 3: star material and how heavy and massive.
• 7:42
  Speaker 2: That would be.
• 7:43
  Speaker 4: And it got me to thinking, what would happen if
• 7:45
  Speaker 4: we actually took that tablespoon or teaspoon of neutron star
• 7:51
  Speaker 4: and dumped it into one of our oceans, And what
• 7:54
  Speaker 4: would happen if we did it on land. I assume
• 7:57
  Speaker 4: heat would be a major factor, but either way, that's
• 8:01
  Speaker 4: my question.
• 8:02
  Speaker 1: Let me know.
• 8:03
  Speaker 2: Thanks. All right, this sounds like a terrible idea, which
• 8:08
  Speaker 2: is why I'm glad you're asked us first. I'm glad
• 8:11
  Speaker 2: he's not an experimental physicist who decided to try this
• 8:16
  Speaker 2: out before asking anyone.
• 8:17
  Speaker 1: And I love the impossible visual of this, you know,
• 8:20
  Speaker 1: a teaspoon of neutron star dumping into the oceans. As
• 8:23
  Speaker 1: if you could like hold a teaspoon of neutron star,
• 8:26
  Speaker 1: like the spoon would be strong enough, or if you
• 8:28
  Speaker 1: were holding it you might be like tempted to lick
• 8:30
  Speaker 1: it or something.
• 8:31
  Speaker 2: Well, I think that's what the question is all abouts.
• 8:33
  Speaker 2: If you want to know what would happen could you
• 8:35
  Speaker 2: take a teaspoon of a neutron star and what would
• 8:37
  Speaker 2: happen if you brought it here to Earth.
• 8:39
  Speaker 1: Yeah, it's a great question, and it really guessed at
• 8:41
  Speaker 1: the heart of some mysteries of modern physics.
• 8:45
  Speaker 2: All right, well break it down, Daniel. What is a
• 8:47
  Speaker 2: neutron star?
• 8:48
  Speaker 1: First of all, a neutron star is one of the
• 8:50
  Speaker 1: possible end states of stars. Stars are big balls of
• 8:54
  Speaker 1: gas that are compressed by gravity to a state where
• 8:56
  Speaker 1: they can perform fusion at their core, creating heavier elements
• 9:00
  Speaker 1: and also a lot of heat and radiation. But eventually
• 9:03
  Speaker 1: that fusion runs out of fuel and gravity wins, collapsing
• 9:06
  Speaker 1: the star. You can either get a white dwarf, which
• 9:08
  Speaker 1: is like a really heavy lump of stuff, or you
• 9:11
  Speaker 1: can get a neutron star if it's even heavier where
• 9:13
  Speaker 1: it overcomes some of the degeneracy pressure and squeezes the
• 9:16
  Speaker 1: electrons and protons down into neutrons, or if you have
• 9:20
  Speaker 1: even more mass than gravity, totally wins and creates a
• 9:23
  Speaker 1: black hole. So a neutron star is incredibly dense remnant
• 9:27
  Speaker 1: of a star?
• 9:28
  Speaker 2: Does it have to be the remnant of a star?
• 9:30
  Speaker 2: You can make a neutron star potentially.
• 9:32
  Speaker 1: Oh, yeah, you can make a neutron star. Step one
• 9:34
  Speaker 1: is make a star.
• 9:35
  Speaker 2: I mean, not necessarily star. I mean you could just
• 9:36
  Speaker 2: take material and squeeze it down enough, and you potentially
• 9:39
  Speaker 2: might make a neutron star.
• 9:41
  Speaker 1: Right if you had like civilization HARDISHEV level three type
• 9:44
  Speaker 1: abilities to do stellar engineering or something, then in principle, yeah,
• 9:48
  Speaker 1: you can make one without making a star. But I
• 9:50
  Speaker 1: think the recipe would be gather a star amount of
• 9:53
  Speaker 1: material and let gravity squeeze it down into a neutron star.
• 9:56
  Speaker 1: Maybe you could speed up the process by applying some
• 9:58
  Speaker 1: external pressure.
• 10:00
  Speaker 2: And why do we need the Kardashians for this, because
• 10:03
  Speaker 2: they're so dense.
• 10:04
  Speaker 1: So many jokes I'm not going to make there about
• 10:06
  Speaker 1: the masses of various Kardashians. No Kardashev level of three.
• 10:10
  Speaker 1: Oh Kardashev.
• 10:11
  Speaker 2: Yes, I see, yes, you said that kind of fast,
• 10:15
  Speaker 2: all right, So then a neutrons are is basically like
• 10:17
  Speaker 2: kind of the heaviest or the densest thing you can
• 10:20
  Speaker 2: have potentially in the universe before it turns into a
• 10:23
  Speaker 2: black hole.
• 10:23
  Speaker 1: Yeah, that's right. Remember that gravity is very powerful, but
• 10:26
  Speaker 1: it's also super duper weak, so it's possible to overcome
• 10:29
  Speaker 1: the effects of gravity, like you can overcome the effects
• 10:31
  Speaker 1: of Earth's gravity is just by jumping. Your muscles are
• 10:34
  Speaker 1: stronger than all the gravity on the Earth, And so
• 10:36
  Speaker 1: the reason everything in the universe doesn't collapse into a
• 10:39
  Speaker 1: black hole is because its structural strength can overcome gravity.
• 10:43
  Speaker 1: So the Earth doesn't collapse into a black hole the
• 10:45
  Speaker 1: size of a peanut because the strength of its material
• 10:48
  Speaker 1: is more powerful than Earth's gravity.
• 10:50
  Speaker 2: I mean, like the individual particles are repelling each other
• 10:53
  Speaker 2: enough to fight the squeezing.
• 10:55
  Speaker 1: Of gravity exactly. But as things get more mass, if
• 10:58
  Speaker 1: you overcome the ability of those four resist So if
• 11:01
  Speaker 1: you added enough mass to the Earth, for example, then
• 11:03
  Speaker 1: it would overcome its structural strength and it would get
• 11:05
  Speaker 1: squeeze down into something like a white dwarf. If you
• 11:09
  Speaker 1: add even more mass than you overcome the next barrier
• 11:12
  Speaker 1: and you get a neutron star. So each of these
• 11:14
  Speaker 1: kinds of states represents overcoming one of these barriers in
• 11:17
  Speaker 1: the battle against gravity, which it eventually will win and
• 11:20
  Speaker 1: turn things into black holes.
• 11:23
  Speaker 2: Now, wait, are you saying a neutron star is not stable,
• 11:25
  Speaker 2: like it'll eventually collapse or can you have a neutron
• 11:28
  Speaker 2: star lasting for a long time?
• 11:30
  Speaker 1: Now, we think neutron stars are stable, but there are
• 11:32
  Speaker 1: black holes out there, and eventually the black holes will
• 11:34
  Speaker 1: just eat everything.
• 11:35
  Speaker 2: Now, when you have a neutron star, did you just
• 11:37
  Speaker 2: have the neutron star or is it like a giant
• 11:40
  Speaker 2: cloud or blob of stuff with the neutron star in
• 11:42
  Speaker 2: the center.
• 11:43
  Speaker 1: Yeah, a lot of the material from the star is
• 11:45
  Speaker 1: blown out. So often you have like a nebula with
• 11:47
  Speaker 1: a neutron star at its heart, and.
• 11:49
  Speaker 2: It's called a neutron star because basically all of the
• 11:52
  Speaker 2: material in it has basically kind of degenerated to be neutrons.
• 11:57
  Speaker 1: Yeah. You start out basically with protons and electrons and
• 12:00
  Speaker 1: weaze them together and they do inverse beta decay into neutrons.
• 12:03
  Speaker 2: You mean the electrons just disappear or they merge with protons.
• 12:07
  Speaker 1: They merge with protons to make a neutron, So like
• 12:09
  Speaker 1: a neutron will decay into a proton and an electron,
• 12:12
  Speaker 1: and there's some neutrino accounting you've got to take care
• 12:14
  Speaker 1: of also. But if you squeeze things down, the inverse
• 12:16
  Speaker 1: can happen, and you can convert a proton and an
• 12:19
  Speaker 1: electron into a neutron. But we don't actually know the
• 12:21
  Speaker 1: state of matter inside a neutron star because it's so intense.
• 12:24
  Speaker 1: The pressure is so great that gravity is powerful and
• 12:28
  Speaker 1: the quantum forces are powerful, so both of those things
• 12:30
  Speaker 1: are at play, and that's not something we know how
• 12:32
  Speaker 1: to reconcile. So the heart of neutron stars really are
• 12:35
  Speaker 1: getting at questions of like quantum gravity situations where you
• 12:38
  Speaker 1: need to understand quantum mechanics and gravity.
• 12:40
  Speaker 2: Wait, wait, are you saying that we don't know if
• 12:42
  Speaker 2: neutron stars are made out of neutrons.
• 12:44
  Speaker 1: We know there's a lot of neutrons in there, but
• 12:46
  Speaker 1: as you get towards the center and the pressure gets
• 12:48
  Speaker 1: really really high, we don't really know. If you can
• 12:50
  Speaker 1: call them neutrons anymore because the neutrons get squeezed so
• 12:53
  Speaker 1: closely together that like the difference between the quarks and
• 12:56
  Speaker 1: one neutron and another neutron becomes artificial, and it might
• 12:59
  Speaker 1: become like a cork gluon plasma. We talked about it
• 13:02
  Speaker 1: in another episode. You might even get things like nuclear
• 13:04
  Speaker 1: pasta weird new forms of matter that quarks and gluons
• 13:07
  Speaker 1: can form under extreme pressure.
• 13:10
  Speaker 2: And what would that pass the taste like very dense
• 13:14
  Speaker 2: vanilla mint.
• 13:15
  Speaker 1: Pineapple, I hope not squidd ink maybe.
• 13:18
  Speaker 2: Or nothing or nothing because it's a neutron star.
• 13:20
  Speaker 1: One of the fascinating things that matter can do is
• 13:23
  Speaker 1: under high pressures, it can form new states. Like if
• 13:25
  Speaker 1: you take carbon and you squeeze it with really high pressure,
• 13:28
  Speaker 1: you get a diamond. But it doesn't always revert when
• 13:30
  Speaker 1: you lower the pressure, Like you make a diamond, you
• 13:32
  Speaker 1: bring it up to the surface of the Earth, it
• 13:33
  Speaker 1: doesn't explode back into carbon. It retains that pressure. What
• 13:37
  Speaker 1: we don't really know is what happens when you make
• 13:39
  Speaker 1: neutron star stuff and then you take it out of
• 13:41
  Speaker 1: the neutron star and put it somewhere else, like on
• 13:44
  Speaker 1: Drew's teaspoon. Is it like a diamond of neutrons star
• 13:47
  Speaker 1: material or does it explode back into a bunch of
• 13:50
  Speaker 1: protons and electrons?
• 13:51
  Speaker 2: Mmm, I feel like we skip the step there. So
• 13:54
  Speaker 2: I guess first of all, the scenario drew withstinol was
• 13:56
  Speaker 2: staying a teaspoon of a neutron star. So, since this
• 14:00
  Speaker 2: is almost the densest stuff in the universe, how much
• 14:01
  Speaker 2: does that teaspoon weight?
• 14:03
  Speaker 1: So a teaspoon of neutron star material has the mass
• 14:06
  Speaker 1: of like ten to the twelve kilograms. That's like a
• 14:09
  Speaker 1: trillion kilograms. It's like a thousand times the mass of
• 14:13
  Speaker 1: the Great Pyramid of Giza.
• 14:15
  Speaker 2: Whoa, And this is like from the surface of the
• 14:18
  Speaker 2: neutron star the center or is this just kind of
• 14:20
  Speaker 2: like an average scoop.
• 14:22
  Speaker 1: This is like an average scoop. It gets more dense
• 14:24
  Speaker 1: at the core and less dense at the edge. But
• 14:26
  Speaker 1: this is like roughly in the middle. But this stuff
• 14:29
  Speaker 1: is like ten to the fifteen times denser than the Sun.
• 14:33
  Speaker 1: It's really incredible. It's like ten to the seventeen kilograms
• 14:36
  Speaker 1: per cubic meter.
• 14:37
  Speaker 2: So the one teaspoon of neutron star you said weighs
• 14:40
  Speaker 2: how many pyramids.
• 14:41
  Speaker 1: Like about a thousand times the Great Pyramid of Giza.
• 14:44
  Speaker 2: Wow, in one little tiny teaspoon. So first of all,
• 14:47
  Speaker 2: I mean, let's forget the fact that it might be
• 14:48
  Speaker 2: hard to take a scoop of a neutron star. But
• 14:51
  Speaker 2: just bringing it to Earth, I mean you'd be carrying
• 14:53
  Speaker 2: a huge amount of weight in this very small space, right, Like,
• 14:57
  Speaker 2: it would probably be really hard to just like hold it.
• 14:59
  Speaker 1: Up, very hard to accelerate it and to bring it
• 15:02
  Speaker 1: to Earth and to gradually lower it down.
• 15:04
  Speaker 2: Yeah, right, because it'd be sort of like balancing a
• 15:07
  Speaker 2: thousand pyramids onto a little tiny point, right. It would
• 15:10
  Speaker 2: probably break or crush anything you try to set it.
• 15:12
  Speaker 1: On exactly, and if you accidentally dropped it while you
• 15:15
  Speaker 1: were in orbit, it would plumb it towards the surface
• 15:17
  Speaker 1: of the Earth and cause a lot of destruction.
• 15:20
  Speaker 2: M because it has a lot of mass, right.
• 15:22
  Speaker 1: It's very strong gravity.
• 15:24
  Speaker 2: Okay, So let's say Drew brought a teaspoon of this stuff,
• 15:27
  Speaker 2: brought it to Earth, and I think maybe the biggest question,
• 15:29
  Speaker 2: as you said, is what would happen to that teaspoon
• 15:31
  Speaker 2: when you first take it out of the nutron star?
• 15:34
  Speaker 2: Because it was it's super dense because the forces in
• 15:37
  Speaker 2: the neutron star are squeezing it together. When you take
• 15:40
  Speaker 2: it out of the nutron star and nothing is squeezing
• 15:42
  Speaker 2: that together, does it just explode or expand the.
• 15:45
  Speaker 1: Short answer is that we don't know, because we don't
• 15:47
  Speaker 1: understand the dynamics inside a neutron star. They are all
• 15:50
  Speaker 1: sorts of theories for what's going on inside of it,
• 15:52
  Speaker 1: nuclear pasta quarklow and plasma, other weird forms of matter.
• 15:56
  Speaker 1: People are writing papers about this every day. Actually do
• 15:59
  Speaker 1: a little bit of research on this topic myself, and
• 16:01
  Speaker 1: there's just a lot of question marks because it's combining
• 16:03
  Speaker 1: two of the hardest things in physics, general relativity, which
• 16:07
  Speaker 1: is very difficult to do any calculations with, and the
• 16:09
  Speaker 1: strong nuclear force, which is a huge headache to do
• 16:11
  Speaker 1: any calculations with. So now you want to understand what's
• 16:14
  Speaker 1: happening when these two things are both doing their thing,
• 16:17
  Speaker 1: it's almost impossible. So we really just don't know. But
• 16:19
  Speaker 1: I suspect that whatever is formed there is not stable,
• 16:22
  Speaker 1: that if you suddenly transport it to Earth, you like
• 16:24
  Speaker 1: build a wormhole between the center of the neutron star
• 16:27
  Speaker 1: and Drew's kitchen and you got a tea spoons worth
• 16:30
  Speaker 1: of material, they would not be stable that it would explode.
• 16:33
  Speaker 2: Right, because there's all this stuff squeezing it together and
• 16:35
  Speaker 2: suddenly nothing squeezing it together. So potentially it might explode.
• 16:38
  Speaker 2: But as you said, it could also maybe be like
• 16:40
  Speaker 2: a diamond, where it is super squeeze carbon, but it's
• 16:43
  Speaker 2: somehow clicked into place, and diamonds don't explode.
• 16:47
  Speaker 1: Diamonds do not explode.
• 16:48
  Speaker 2: Yes, that's true, and so how bad would it be
• 16:50
  Speaker 2: for this thing to explode here on Earth?
• 16:52
  Speaker 1: It would be really really bad. Material with that density
• 16:56
  Speaker 1: has really high kinetic energy, like the particles inside of
• 16:59
  Speaker 1: it are whizzing around with incredible velocity kinetic energy.
• 17:03
  Speaker 2: Why does it necessarily have kinetic energy?
• 17:05
  Speaker 1: Well, think about how it was formed. You took a
• 17:07
  Speaker 1: thousand pyramids of gizo's worth of hydrogen, for example, as
• 17:11
  Speaker 1: a big diffuse gas, and you squeeze it down to
• 17:14
  Speaker 1: a t spoon. To do that, you're pushing on it.
• 17:16
  Speaker 1: If you have walls, for example, every time you're pushing
• 17:19
  Speaker 1: those walls closer and closer, you're pushing on those particles.
• 17:22
  Speaker 1: So applying that pressure to squeeze this down pushes on
• 17:25
  Speaker 1: all the particles and now they have very very high energy.
• 17:27
  Speaker 2: Right, that's find you maybe form a neutron star. But
• 17:30
  Speaker 2: what if I take my a neutron star and I
• 17:32
  Speaker 2: freeze it before taking a scoop out of it? Did
• 17:34
  Speaker 2: I just blow your mind?
• 17:38
  Speaker 1: Hm? I love the idea of like deep freezing a
• 17:40
  Speaker 1: bit of neutron star, and then you could like deep
• 17:42
  Speaker 1: fry it, and then you could take a bite out of.
• 17:44
  Speaker 2: It, deep freeze the neutron star, yet the whole star,
• 17:47
  Speaker 2: and then you take a scoop.
• 17:49
  Speaker 1: I think it's impossible to cool down a neutron star
• 17:52
  Speaker 1: because of the quantum mechanics of neutrons. The issue is
• 17:55
  Speaker 1: that neutrons are fermions like electrons and other particles. You
• 17:58
  Speaker 1: can't have two of them in the same state, and
• 18:00
  Speaker 1: so that creates a minimum temperature for neutron stars because basically,
• 18:04
  Speaker 1: if you have one neutron in like a really low
• 18:06
  Speaker 1: energy state, then you can't have another one. The next
• 18:08
  Speaker 1: one has to get into the next high energy state,
• 18:11
  Speaker 1: so there's like a minimum energy.
• 18:13
  Speaker 2: What would happen if you tried to freeze a neutron star.
• 18:15
  Speaker 1: You just couldn't get that neutron into a lower state, like,
• 18:17
  Speaker 1: they just don't go into that lower state if it's
• 18:20
  Speaker 1: already occupied. It's like trying to get two electrons into
• 18:22
  Speaker 1: the same state of hydrogen. No amount of cooling will
• 18:25
  Speaker 1: get them that low. The electrons will just refuse to
• 18:28
  Speaker 1: do that. They won't give up the energy.
• 18:30
  Speaker 2: They can't sort of like maybe how you can't freeze
• 18:34
  Speaker 2: an atom technically, right, at some point the electrons are
• 18:37
  Speaker 2: still orbiting around the nucleus.
• 18:40
  Speaker 1: And this actually touches on the topic of our next question.
• 18:42
  Speaker 2: All right, So, continuing with the scoop of a neutron star,
• 18:45
  Speaker 2: you're saying it would have a lot of compressed energy
• 18:48
  Speaker 2: in there, and so when you take away the gravity,
• 18:50
  Speaker 2: maybe all that energy would be released.
• 18:52
  Speaker 1: Yeah, exactly. And the amount of energy is really incredible.
• 18:55
  Speaker 1: It's a little bit of calculation. It's more energy than
• 18:58
  Speaker 1: the sun emits of second. It's about equivalent to one
• 19:03
  Speaker 1: billion atomic bombs.
• 19:05
  Speaker 2: WHOA, that would be bad news for all of us.
• 19:09
  Speaker 1: Yes, very very bad news for everybody. Neutrons are very dangerous.
• 19:13
  Speaker 1: They are hadronic particles and if they go through you,
• 19:15
  Speaker 1: they don't have electric charge. But they're basically just like
• 19:17
  Speaker 1: tiny bullets and they can really do a lot of damage.
• 19:20
  Speaker 1: And if you have a bunch of neutrons really high
• 19:22
  Speaker 1: compressed and then they explode with high speed, you have
• 19:25
  Speaker 1: like ten to the thirty eight neutrons traveling at some
• 19:28
  Speaker 1: significant fraction of the speed of light. It's an enormous
• 19:31
  Speaker 1: amount of energy deposited everywhere. And so you might wonder like, oh,
• 19:34
  Speaker 1: is it going to drop through the Earth or whatever. No,
• 19:36
  Speaker 1: it's just going to explode and basically vaporize a huge
• 19:39
  Speaker 1: chunk of the Earth.
• 19:40
  Speaker 2: Well, I guess you know, if you are able to
• 19:42
  Speaker 2: get it front the neutron star to the Earth, it
• 19:45
  Speaker 2: must be sort of stable though, right.
• 19:48
  Speaker 1: It depends like maybe you used a wormhole. So you
• 19:50
  Speaker 1: just like open up a wormhole between the center of
• 19:52
  Speaker 1: the neutron star and Drew's kitchen and then a little
• 19:55
  Speaker 1: bit leak through.
• 19:56
  Speaker 2: Oh I see if you just use magic is what
• 19:58
  Speaker 2: you're saying.
• 19:59
  Speaker 1: Wormhold or not magic. I think it's probably impossible to
• 20:02
  Speaker 1: take a spoonfull of neutron star and transport it through
• 20:05
  Speaker 1: space to Drew's kitchen. I think that's probably impossible.
• 20:09
  Speaker 2: Well, I guess either way, it's bad news.
• 20:11
  Speaker 1: It's bad news and the rest of us. It would
• 20:14
  Speaker 1: be like a huge asteroid hitting the Earth, something like
• 20:17
  Speaker 1: several thousand times the devastation of the dinosaur killer that
• 20:21
  Speaker 1: hit sixty five million years ago. So definitely bad news.
• 20:25
  Speaker 2: Like maybe at the scale of the asteroid or rock
• 20:28
  Speaker 2: that created the Moon perhaps.
• 20:29
  Speaker 1: Or more maybe not that dramatic, but almost that scale. Yes,
• 20:33
  Speaker 1: Like the Earth would look different. You could see it
• 20:35
  Speaker 1: from space for sure, bad news for Drew and all
• 20:38
  Speaker 1: of his neighbors and the rest of us on Earth.
• 20:41
  Speaker 2: I see, all right, well, I guess the answer for drewis, Hey, Drew,
• 20:44
  Speaker 2: maybe you should eat the teaspoon before you bring it
• 20:46
  Speaker 2: to Earth.
• 20:48
  Speaker 1: Don't order a teaspoon of neutron star on Instacart please.
• 20:52
  Speaker 2: That's right on wormhold card. Exact age would not be good.
• 20:55
  Speaker 2: All right, thanks Drew for that question. Let's get to
• 20:57
  Speaker 2: our other questions here today. We have questions about gravity
• 21:00
  Speaker 2: pressure and about orbital dynamics, say said heavy stuff. We'll
• 21:04
  Speaker 2: get to that, but first let's take a quick break.
• 21:19
  Speaker 2: We're taking listener questions here today, and our next question
• 21:22
  Speaker 2: comes from Nol from Perth.
• 21:24
  Speaker 5: Good day, Daniel, and Hi, this is Noel from Perth, Australia.
• 21:28
  Speaker 5: I was sitting here thinking one day I wonder if
• 21:31
  Speaker 5: matter under extreme pressure can ever be stopped. What I
• 21:35
  Speaker 5: mean by that is, is there ever a point where
• 21:38
  Speaker 5: we have so much gravitational pressure that all movement of
• 21:43
  Speaker 5: matter can be frozen in time? Is that possible? Would
• 21:48
  Speaker 5: love to hear your answer on this one. Thank you
• 21:50
  Speaker 5: very much and love hearing your podcast. Cheers mate.
• 21:53
  Speaker 2: See all right, gooday to two nol or good eight.
• 21:57
  Speaker 2: I guess technically I'm not quite sure I understood this question.
• 22:00
  Speaker 2: What do you think nol here is asking.
• 22:02
  Speaker 1: I think Noel has heard that you can't cool matter
• 22:05
  Speaker 1: down so that things actually stop forever, like absolute zero
• 22:08
  Speaker 1: is impossible in quantum mechanics. But he's wondering if instead
• 22:11
  Speaker 1: you can use pressure. You could just like squeeze stuff
• 22:14
  Speaker 1: down so that it stops moving.
• 22:16
  Speaker 3: Oh.
• 22:17
  Speaker 2: I see, so we're talking kind of about the same
• 22:19
  Speaker 2: question we talked about just now in the other question, Yeah,
• 22:21
  Speaker 2: which is like, what's the coldest that you can get something,
• 22:25
  Speaker 2: especially if it's super dense like a neutron star.
• 22:28
  Speaker 1: Yeah, and he's probably also wondering, like is matter moving
• 22:31
  Speaker 1: inside a singularity inside a black hole? Oh?
• 22:34
  Speaker 2: Really? That's in here also it's a very dense question.
• 22:38
  Speaker 1: He's wondering about the extremes of gravitational pressure, are you I.
• 22:42
  Speaker 2: See, I see. Well, I guess I wouldn't necessarily associate
• 22:45
  Speaker 2: extreme pressure with things stopping. In fact, I kind of associate,
• 22:49
  Speaker 2: you know, the intense gravity inside of the sun to
• 22:52
  Speaker 2: like fusion and things just getting hotter and hotter, or
• 22:54
  Speaker 2: like we talked about the neutron star, just gets hotter
• 22:56
  Speaker 2: the more you compress it.
• 22:57
  Speaker 1: Yeah, exactly. It's like if your toddler is going crazy
• 23:00
  Speaker 1: and you lock them in the room, They're not necessarily
• 23:03
  Speaker 1: just going to calm down. They might just bounce off
• 23:04
  Speaker 1: the walls. Same thing happens if you take an electron
• 23:06
  Speaker 1: and try to squeeze it down to a smaller and
• 23:09
  Speaker 1: smaller space.
• 23:10
  Speaker 2: Well, let's maybe start with the concept that he talks about,
• 23:12
  Speaker 2: which is getting things to stop. And I guess what
• 23:15
  Speaker 2: he means is like cooling things down or squeezing them
• 23:18
  Speaker 2: so much where they don't have any kinetic energy or
• 23:20
  Speaker 2: they're not moving.
• 23:21
  Speaker 1: Yeah, he talks about it being frozen in time, so
• 23:23
  Speaker 1: no kinetic energy. So you want to simultaneously squeeze stuff
• 23:27
  Speaker 1: down plus pull out that kinetic energy. Somehow cool it
• 23:31
  Speaker 1: and squeeze it at the same time.
• 23:33
  Speaker 2: What do you think frozen in time means doesn't change
• 23:35
  Speaker 2: over time at all?
• 23:36
  Speaker 1: Yeah exactly, that's just not moving. I think he's interested
• 23:39
  Speaker 1: in absolute zero essentially, like finding a path to getting
• 23:43
  Speaker 1: things completely frozen.
• 23:44
  Speaker 3: Mmm.
• 23:45
  Speaker 2: I see, But absolute zero does exist right in the universe.
• 23:49
  Speaker 1: Absolute zero does exist, But quantum mechanics tells us it's
• 23:51
  Speaker 1: impossible for anything to actually be stopped because that would
• 23:55
  Speaker 1: violate some basic principles. There's a minimum amount of energy
• 23:58
  Speaker 1: everything has to have in the universe according to quantum mechanics.
• 24:00
  Speaker 1: So you can't actually ever get material to absolute zero.
• 24:04
  Speaker 2: Like anything that has matter or substance to it, you
• 24:07
  Speaker 2: can't freeze it down to zero. Is that things that
• 24:10
  Speaker 2: are always going to be jiggling a little bit or
• 24:12
  Speaker 2: moving or having some sort of minimum energy just from
• 24:15
  Speaker 2: having the minimum quantum property.
• 24:18
  Speaker 1: Yeah, exactly. And there's a few ways to think about that.
• 24:20
  Speaker 1: One is in terms of the uncertainty principle, Like if
• 24:23
  Speaker 1: something has zero energy, then you know its location and
• 24:27
  Speaker 1: you know it's momentum both zero and you know both
• 24:29
  Speaker 1: of those perfectly well, and that violates the uncertainty principle.
• 24:32
  Speaker 1: So the uncertainty principle tells you if you locate something
• 24:35
  Speaker 1: in one position, you squeeze it down super well, then
• 24:37
  Speaker 1: the uncertainly on its momentum is infinite. Right, So essentially,
• 24:40
  Speaker 1: squeezing something down to just one location you give it
• 24:43
  Speaker 1: infinite temperature. So that tells you you can't. Another way
• 24:46
  Speaker 1: to think about it is just in terms of the
• 24:48
  Speaker 1: solutions of quantum fields, like what are quantum fields? These
• 24:51
  Speaker 1: things that fill space and they vibrate, but if you
• 24:53
  Speaker 1: look at the mathematics of them, they can vibrate in
• 24:55
  Speaker 1: various ways, but they can never have zero energy. That
• 24:59
  Speaker 1: configuration with the field has zero energy is not a
• 25:01
  Speaker 1: solution to the wave equations. The wave equations require a
• 25:04
  Speaker 1: minimum amount of buzzing in these fields at all times.
• 25:09
  Speaker 2: But then no, I guess is imagining a scenario where
• 25:11
  Speaker 2: maybe you squeeze things so much that they can't move anymore. Like,
• 25:15
  Speaker 2: for example, if you take a gas and you squeeze it.
• 25:18
  Speaker 2: As a gas, it's moving, all the particles in it
• 25:20
  Speaker 2: are moving a lot, but as you squeeze it, maybe
• 25:22
  Speaker 2: it turns first into I guess, liquid hydrogen, which makes
• 25:25
  Speaker 2: the molecules there moveless, and then you keep squeezing it,
• 25:29
  Speaker 2: you'll actually get like hydrogen ice, right, and then the
• 25:32
  Speaker 2: atoms are almost not moving at all, maybe they're still vibrating.
• 25:35
  Speaker 2: And so the question is, maybe if you keep squeezing
• 25:37
  Speaker 2: beyond solid, can you actually make the molecules and the
• 25:40
  Speaker 2: atoms in there stop?
• 25:42
  Speaker 1: Yeah, exactly. It's sort of a fund mental question. And
• 25:45
  Speaker 1: you know, if you put quantum mechanics aside and just
• 25:47
  Speaker 1: think about like the classical universe, where everything has like
• 25:49
  Speaker 1: a location and path through space and time, then there's
• 25:53
  Speaker 1: no issue. You could take something, you could squeeze it down,
• 25:56
  Speaker 1: you could give it zero energy, not a problem at all.
• 25:59
  Speaker 1: If you think of tiny particles, is just like little
• 26:02
  Speaker 1: grains of sand. Right. The issue really is with quantum
• 26:05
  Speaker 1: mechanics that these particles are not little grains of sand.
• 26:08
  Speaker 1: They follow different rules, so they do all have minimum energy,
• 26:11
  Speaker 1: and they have uncertainty on them, and they also follow
• 26:14
  Speaker 1: these other rules like the poly exclusion principle. If you
• 26:16
  Speaker 1: have a big pile of electrons, you can't squeeze them
• 26:19
  Speaker 1: all down to zero energy because they won't be in
• 26:21
  Speaker 1: the same energy level. Fermions will not allow another fermion
• 26:25
  Speaker 1: in the same energy level, the same quantum state. So
• 26:27
  Speaker 1: there's a minimum energy to all those electrons. That's sometimes
• 26:30
  Speaker 1: called electron degeneracy pressure. It's one of the things that
• 26:33
  Speaker 1: keeps a white dwarf from collapsing, for example.
• 26:36
  Speaker 2: But I guess maybe, just as a matter of exercise,
• 26:39
  Speaker 2: let's maybe follow Knowle's reasoning here and let's just keep
• 26:43
  Speaker 2: squeezing things, right, So if you squeeze things more, they'll
• 26:45
  Speaker 2: get solid. Then eventually they'll turn into neutron stars, right,
• 26:49
  Speaker 2: which is what we talked about in the previous question.
• 26:51
  Speaker 1: Yeah, exactly, Then be neutron stars. And now we're already
• 26:54
  Speaker 1: beyond level of knowledge because we don't know what's going
• 26:57
  Speaker 1: on inside a neutron star. Maybe there's nuclear pasta, maybe
• 27:00
  Speaker 1: there's weird new kinds of crystals, maybe weird neutron diamonds.
• 27:03
  Speaker 2: We just don't know, right, So is it possible that
• 27:05
  Speaker 2: inside of an entrance star things stop, like things click
• 27:09
  Speaker 2: into place in such a way that they kind of
• 27:11
  Speaker 2: have zero energy.
• 27:12
  Speaker 1: I think the most correct answer is to just say
• 27:14
  Speaker 1: we don't know, because it depends on the details of
• 27:17
  Speaker 1: quantum gravity, like what happens to particles when you're under
• 27:21
  Speaker 1: really intense pressure and really intense gravity. We just don't
• 27:24
  Speaker 1: know the answer to that. We need a theory of
• 27:26
  Speaker 1: quantum gravity that tells us how to do gravitational calculations
• 27:29
  Speaker 1: for particles. So we're just speculating, and it might be
• 27:31
  Speaker 1: that there are some theories of quantum gravity that reveal
• 27:33
  Speaker 1: the universe is very different from the way that we expect.
• 27:35
  Speaker 1: That we can't just extrapolate our quantum rules down to
• 27:39
  Speaker 1: very very high pressures and very high densities.
• 27:41
  Speaker 2: Any like, if we keep squeezing something, maybe at some
• 27:43
  Speaker 2: point the Heisenberg uncertainty principle doesn't work. M m like
• 27:47
  Speaker 2: extreme gravity is maybe Heisenberg takesification.
• 27:50
  Speaker 1: Yeah, Like, let me say it this way. General relativity says, yes,
• 27:53
  Speaker 1: that's no problem. You can squeeze things down to infinite
• 27:56
  Speaker 1: density and zero velocity. That's the singularity at the heart
• 27:58
  Speaker 1: of a black hole, for example. CIS says No, as
• 28:01
  Speaker 1: you squeeze things down, they get higher and higher energy,
• 28:03
  Speaker 1: and so it's impossible to get things down to zero velocity.
• 28:07
  Speaker 1: But the crux is which wins at these very high
• 28:09
  Speaker 1: I densities. What's actually going on inside a black hole?
• 28:12
  Speaker 1: As you've pointed out, many times. I'm biased towards quantum mechanics,
• 28:15
  Speaker 1: and I suspect that we can extrapolate from quantum mechanics
• 28:17
  Speaker 1: and think that whatever is going on at the heart
• 28:19
  Speaker 1: of black holes or in neutron stars or in Nole's
• 28:22
  Speaker 1: kitchen is going to be more like quantum mechanics than
• 28:25
  Speaker 1: like general relativity. But I could be wrong, and it
• 28:27
  Speaker 1: could be very surprising, and it could be more gravitational,
• 28:29
  Speaker 1: more classical than we expect.
• 28:31
  Speaker 2: Yeah, yeah, no, I'm definitely in the vanilla camp. I
• 28:34
  Speaker 2: think vanilla wins at the end, meaning like maybe general
• 28:38
  Speaker 2: relativity wins at the end, and maybe things do freeze
• 28:40
  Speaker 2: and then stop moving, right, yeah, or you know, at
• 28:43
  Speaker 2: some point you make a black hole if you squeeze
• 28:45
  Speaker 2: things enough, which technically does freeze time. Right, isn't time
• 28:49
  Speaker 2: frozen on the surface of a black hole? And definitely
• 28:52
  Speaker 2: just inside of a black hole, is in time technically frozen.
• 28:54
  Speaker 1: M Yes. Absolutely. Then again, we have all sorts of
• 28:57
  Speaker 1: reasons why we think general relativity must to be wrong
• 29:00
  Speaker 1: and can't be an accurate description of what's going on
• 29:03
  Speaker 1: in the universe. But again, it's a big open question.
• 29:06
  Speaker 1: We don't know the answer to these things. And we
• 29:07
  Speaker 1: could certainly be wrong. All we can do right now
• 29:10
  Speaker 1: is extrapolate from quantum mechanics, or extrapolate from general relativity,
• 29:13
  Speaker 1: or wait until some genius combines the two and gives
• 29:16
  Speaker 1: us a picture of quantum gravity.
• 29:17
  Speaker 2: Mmm, so somebody makes neopolitan ice cream out of a
• 29:21
  Speaker 2: black hole? No, but with the black hole, don't we
• 29:24
  Speaker 2: know they look like that. Time stops on the surface
• 29:27
  Speaker 2: of a black hole, so it wouldn't that technically freeze things?
• 29:30
  Speaker 2: As Noel suggests.
• 29:31
  Speaker 1: Time stops at the event horizon for a distant observer.
• 29:34
  Speaker 1: For somebody falling into a black hole, time doesn't stop,
• 29:36
  Speaker 1: and you can continue to do your dance, or eat
• 29:38
  Speaker 1: your ice cream, or take a bite out of whatever
• 29:40
  Speaker 1: else you see inside the black hole.
• 29:42
  Speaker 2: Yeah, but to us, they would appear frozen.
• 29:44
  Speaker 1: To us, they would appear frozen. Yes, but again that
• 29:46
  Speaker 1: violates quantum mechanics. So who knows if it's really true?
• 29:49
  Speaker 1: But yes, general relativity allows things to freeze to zero velocity.
• 29:53
  Speaker 2: All right, Well, no, I guess that's the answer for you.
• 29:56
  Speaker 2: Daniel doesn't know. Nobody knows on that angel question of
• 30:02
  Speaker 2: what's going on inside of a black hole, because that's
• 30:04
  Speaker 2: the ultimate I guess a squeezing of things due to
• 30:07
  Speaker 2: gravitational pressure.
• 30:08
  Speaker 1: I feel like as this podcast goes along, more and
• 30:10
  Speaker 1: more the questions have the same answer, which is, we
• 30:13
  Speaker 1: don't know because we don't know quantum gravity.
• 30:15
  Speaker 2: Gosh, why did you just fix that? Daniel, let's figure
• 30:17
  Speaker 2: it out. What are you doing spending time on this
• 30:20
  Speaker 2: podcast when you can be solving the biggest question we have?
• 30:24
  Speaker 1: Yeah, well, just before we recorded this, I was eating
• 30:26
  Speaker 1: some pineapple cake and trying to think deeply about the
• 30:29
  Speaker 1: nature of condensed matter. But I didn't quite figure it out.
• 30:31
  Speaker 2: It didn't work. Huh. Just gonna have to keep on trying. Yeah,
• 30:36
  Speaker 2: I'm sure your doctor will have something to say about that.
• 30:39
  Speaker 2: All right, well, thanks for that question. Now, now let's
• 30:41
  Speaker 2: get to our last question. This one is about orbital
• 30:45
  Speaker 2: dynamics and shared atmosphere, so let's explore that out there
• 30:49
  Speaker 2: in space. But first let's take another quick break.
• 31:03
  Speaker 5: All right.
• 31:04
  Speaker 2: We're askering listener questions here today, and our last question
• 31:06
  Speaker 2: here comes from Joe Hey.
• 31:08
  Speaker 6: Daniel, and Jorge. I had a question about something I
• 31:11
  Speaker 6: saw on the show Foundation, where a planet and its
• 31:14
  Speaker 6: moon shared an atmosphere, and I was wondering if that's
• 31:17
  Speaker 6: actually possible. I look forward to hearing what you guys
• 31:20
  Speaker 6: have to say.
• 31:21
  Speaker 2: All right, cool question. That's a fun show. Do you
• 31:23
  Speaker 2: watch that show, Daniel?
• 31:24
  Speaker 1: Yeah, I read all these books and I watched the show.
• 31:27
  Speaker 1: It's a lot of fun and I love that scene
• 31:29
  Speaker 1: that he's talking about.
• 31:30
  Speaker 2: So I read all the books several times when I
• 31:32
  Speaker 2: was younger, and I was very excited about the show.
• 31:34
  Speaker 2: Loved the first season. Second season, I was like, I'm out.
• 31:40
  Speaker 2: It just deviated a little bit too much from the
• 31:42
  Speaker 2: books for my day. So I guess this is thank
• 31:44
  Speaker 2: be a spoiler, but I'm probably not gonna watch it,
• 31:46
  Speaker 2: so I guess we can talk about it.
• 31:47
  Speaker 1: Yeah, this doesn't really spoil any of the plot. It's
• 31:49
  Speaker 1: just a really cool, clever scene. One of the things
• 31:52
  Speaker 1: I liked about the show is that it did dv
• 31:53
  Speaker 1: from the books. It sort of lives in the same
• 31:55
  Speaker 1: universe as the books, but doesn't just take those storylines,
• 31:59
  Speaker 1: which I thought.
• 31:59
  Speaker 2: Was creety, You mean it has the same foundation exactly.
• 32:04
  Speaker 1: It's fundamentally the same universe.
• 32:06
  Speaker 2: Except people have crazy superpowers.
• 32:07
  Speaker 1: Right. Yeah, But here Joe's talking about a really striking
• 32:10
  Speaker 1: scene where there's a herd of some kind of animal
• 32:12
  Speaker 1: and they take a running leap off of a hill
• 32:15
  Speaker 1: and they land on a moon that's orbiting very very
• 32:18
  Speaker 1: close by. So there's like continuous atmosphere between the planet
• 32:21
  Speaker 1: and its moon, so that you can jump from one
• 32:24
  Speaker 1: to the other.
• 32:25
  Speaker 2: What how big is this moon in this planet, like
• 32:28
  Speaker 2: sort of Earth size or what.
• 32:29
  Speaker 1: Yeah, that's a great question. I don't remember the details.
• 32:32
  Speaker 1: It was definitely pretty big in the sky. So this
• 32:35
  Speaker 1: is a real size planet and a real size moon,
• 32:37
  Speaker 1: I mean big enough to have an atmosphere.
• 32:39
  Speaker 2: So it's more like a dual planet, kind of like
• 32:41
  Speaker 2: a twin planet sort of.
• 32:43
  Speaker 1: One of them was definitely smaller than the other, so
• 32:44
  Speaker 1: I'm sure astronomers would have a fun time arguing about
• 32:47
  Speaker 1: whether one was the moon or they were binary planets.
• 32:50
  Speaker 2: To be like, that's not a moon. So then in
• 32:53
  Speaker 2: the show, there's a planet with a large sized moon
• 32:56
  Speaker 2: that is orbiting around the planet, but it's so close
• 32:59
  Speaker 2: that you can sort of jump between them.
• 33:02
  Speaker 1: Yeah, exactly.
• 33:03
  Speaker 2: Now there's two things here, like one is this technically possible?
• 33:06
  Speaker 2: Like can you have a moon that big orbiting that
• 33:09
  Speaker 2: close to a planet? And the other question, I guess
• 33:12
  Speaker 2: is would they share an atmosphere.
• 33:14
  Speaker 1: Yeah, exactly. So the first question has to do basically
• 33:17
  Speaker 1: with gravitational tidal forces, because if you just think about
• 33:20
  Speaker 1: the planets as points, there's no reason why they can't
• 33:23
  Speaker 1: orbit super duper close to each other. Like gravity works
• 33:25
  Speaker 1: really far away, gravity works really close together. You can
• 33:28
  Speaker 1: get two things close together and orbiting. The reason it
• 33:31
  Speaker 1: might not work is because of the tidal forces.
• 33:34
  Speaker 2: Wait, wait, you're saying, technically it's possible, like our Moon
• 33:37
  Speaker 2: could orbit really close to us enough for us to
• 33:40
  Speaker 2: jump to it potentially.
• 33:41
  Speaker 1: Potentially if you ignore the tidal forces. The tidal forces
• 33:44
  Speaker 1: are the crux of the issue.
• 33:45
  Speaker 2: But something that big orbiting wouldn't it have to be
• 33:48
  Speaker 2: going super duper fast, Like what are the orbital dynamics there?
• 33:51
  Speaker 1: Yes, absolutely, the closer you get, the smaller the radio
• 33:54
  Speaker 1: is the higher of the velocity. So if you were
• 33:56
  Speaker 1: like orbiting the Earth one meter above its surface, you'd
• 33:59
  Speaker 1: have to go very very fast, where you could be
• 34:01
  Speaker 1: moving more slowly if you were further away.
• 34:03
  Speaker 2: I feel like I've seen a YouTube video about this,
• 34:05
  Speaker 2: which I know is not the most reliable source, but
• 34:08
  Speaker 2: I think at some point like you wouldn't get a
• 34:10
  Speaker 2: stable orbit like at some point the Moon would start
• 34:13
  Speaker 2: to spiral in and fall to the Earth. Maybe there's
• 34:15
  Speaker 2: no actual orbit that could make that work.
• 34:18
  Speaker 1: Well, the equations are pretty simple if you're talking about
• 34:20
  Speaker 1: just two points, and if you're ignoring things like drag
• 34:23
  Speaker 1: and tidle forces, then you can have orbits at any stage,
• 34:27
  Speaker 1: Like you could have two grains of sand orbiting each
• 34:29
  Speaker 1: other in deep space very close together.
• 34:31
  Speaker 2: But wouldn't they be going super duper fast or wouldn't
• 34:34
  Speaker 2: the orbits be like super stretched out.
• 34:37
  Speaker 1: Yeah, they certainly could. But if again, if it's just
• 34:39
  Speaker 1: two points with no drag, no friction, no tidle forces,
• 34:42
  Speaker 1: then the math is pretty simple.
• 34:43
  Speaker 2: All right, so it sounds like it's possible, but you're
• 34:45
  Speaker 2: saying tidle forces would make this impossible exactly.
• 34:48
  Speaker 1: You can calculate the gravity between two points. That's pretty simple.
• 34:51
  Speaker 1: But now take one of those things and say what
• 34:53
  Speaker 1: if it's not a point, what if it has real
• 34:54
  Speaker 1: size to it? You know, inflate it from a point
• 34:57
  Speaker 1: to like a basketball or a moon or whatever. Now,
• 34:59
  Speaker 1: part of that thing is closer to the object that's orbiting,
• 35:01
  Speaker 1: and part of it's further away. You have like the
• 35:03
  Speaker 1: near side and the far side. Because gravity depends on distance,
• 35:07
  Speaker 1: those two pieces are now feeling different amounts of gravity.
• 35:10
  Speaker 1: The closer side of the Moon feels Earth's gravity more
• 35:12
  Speaker 1: than the far side of the Moon, for example, and
• 35:14
  Speaker 1: that's the tidal force. The difference between the strength of
• 35:17
  Speaker 1: gravity on one side and the other is effectively a
• 35:19
  Speaker 1: force pulling that object apart.
• 35:22
  Speaker 2: So there would be a force on the Moon splitting
• 35:25
  Speaker 2: it into two.
• 35:26
  Speaker 1: Yeah exactly. And that's why as you approach a black hole,
• 35:28
  Speaker 1: for example, the tidal forces can pull you apart because
• 35:32
  Speaker 1: in really intense gravity, the difference between the force on
• 35:34
  Speaker 1: your feet and the force on your head can be
• 35:36
  Speaker 1: enough to overcome the structural integrity of your body. And
• 35:39
  Speaker 1: this is why, for example, some planets have rings and
• 35:42
  Speaker 1: some planets have moons, because if the stuff is too
• 35:45
  Speaker 1: close to the planet, it's within some limit called the
• 35:48
  Speaker 1: Roche limit, then the tidal forces of the planet would
• 35:50
  Speaker 1: tear apart any moon and turn it into rings.
• 35:53
  Speaker 2: M So I guess if this moon is not you know,
• 35:56
  Speaker 2: stick enough or dense enough or strong enough, it would
• 35:58
  Speaker 2: break apart.
• 35:59
  Speaker 1: Yeah, exactly. And so it depends on the structural strength
• 36:01
  Speaker 1: of the moon. Like if you have a moon made
• 36:03
  Speaker 1: of water. It's much easier to tear apart than if
• 36:05
  Speaker 1: you had a moon made of diamond, for example. So
• 36:08
  Speaker 1: it's not just like a hard and fast limit around
• 36:10
  Speaker 1: any object. You have to take intoccount lots of different things.
• 36:12
  Speaker 1: It's a rough guide, so it depends on the masses
• 36:14
  Speaker 1: of the planets and the rigidity the satellite. But I
• 36:16
  Speaker 1: looked into a few calculations, and if you had two earths,
• 36:19
  Speaker 1: for example, and estimating what their structural integrity are, the
• 36:23
  Speaker 1: two earths could orbit each other as long as the
• 36:25
  Speaker 1: surfaces were more than one thousand kilometers apart.
• 36:28
  Speaker 2: What which is very little, right.
• 36:30
  Speaker 1: Yeah, it's like a sixth of the radius of the Earth. Wow,
• 36:33
  Speaker 1: so you couldn't jump a thousand kilometers, but a thousand
• 36:36
  Speaker 1: kilometers is not that far. The Earth would be really
• 36:38
  Speaker 1: big in the sky.
• 36:39
  Speaker 2: Well, you would only need to jump five hundred kilometers
• 36:42
  Speaker 2: because then you would get sucked into the gravity of
• 36:44
  Speaker 2: the other planet.
• 36:46
  Speaker 1: That's true. But if you jump five hundred kilometers and
• 36:48
  Speaker 1: you got stuck there, you'd be like right between the
• 36:50
  Speaker 1: gravity of the two I guess that would be kind
• 36:52
  Speaker 1: of cool.
• 36:52
  Speaker 2: Also, well, it would be kind of unstable, Like how
• 36:54
  Speaker 2: fast would these two earths be orbiting around each other.
• 36:56
  Speaker 2: Did you calculate that?
• 36:57
  Speaker 1: I didn't calculate that, But it would be very very.
• 36:59
  Speaker 2: Fast, super duper fast.
• 37:01
  Speaker 1: Right, We're duper fast exactly because they have to avoid
• 37:04
  Speaker 1: falling into each other.
• 37:05
  Speaker 2: Right, That's what I was trying to say earlier, Like,
• 37:07
  Speaker 2: at some point these orbits get unreasonably fast.
• 37:10
  Speaker 1: I guess there could be a limit at the speed
• 37:12
  Speaker 1: of light, right, So there might be some radius at
• 37:15
  Speaker 1: which things need to go faster than the speed of
• 37:17
  Speaker 1: light to avoid falling in and then there's no orbit.
• 37:19
  Speaker 1: Maybe that's what you're referring to earlier.
• 37:21
  Speaker 2: Or you know, at some point you're just spinning too fast,
• 37:23
  Speaker 2: everything would fly off the surface of the Earth.
• 37:25
  Speaker 1: Yeah, that's true.
• 37:26
  Speaker 2: Or that you wouldn't be able to hold an atmosphere maybe, Yeah.
• 37:28
  Speaker 1: The atmosphere is definitely an issue also because an atmosphere
• 37:31
  Speaker 1: provides drag, right, And so if the Earth has an
• 37:34
  Speaker 1: atmosphere and the other Earth has an atmosphere and they're
• 37:37
  Speaker 1: that close together, then they're going to be dragging on
• 37:39
  Speaker 1: each other. They're not just flying through empty space conserving
• 37:42
  Speaker 1: their kinetic energy. They're losing energy the same way that
• 37:45
  Speaker 1: like the Iss loses energy as it goes around the
• 37:47
  Speaker 1: Earth because it's not in very high orbit, and so
• 37:50
  Speaker 1: there's a little bit of drag there and has to
• 37:52
  Speaker 1: constantly like bump itself up to avoid falling into the Earth.
• 37:55
  Speaker 1: We have an atmosphere and the other Earth has an atmosphere.
• 37:57
  Speaker 1: We're orbiting each other that close, we're going to be
• 37:59
  Speaker 1: dragging on you each other a little bit.
• 38:01
  Speaker 2: Okay, but it sounds like you're saying it is kind
• 38:03
  Speaker 2: of possible if this Moon is made out of diamonds
• 38:06
  Speaker 2: and it's okay that it's going so fast. Yeah, maybe
• 38:08
  Speaker 2: we don't have such a need for an atmosphere between
• 38:11
  Speaker 2: these two planets.
• 38:12
  Speaker 1: But there's also maybe a solution there, like if you
• 38:14
  Speaker 1: could end up in like a geosynchronous orbit and get
• 38:17
  Speaker 1: tidal locking, like imagine the Moon is basically always above
• 38:21
  Speaker 1: the same spot on the Earth, you're not actually dragging
• 38:24
  Speaker 1: through the atmosphere. And if you get tidal locking, so
• 38:26
  Speaker 1: they're not spinning a relative to each other, the two
• 38:28
  Speaker 1: faces of the objects are facing each other constantly, then
• 38:32
  Speaker 1: you could imagine having an atmosphere. You wouldn't be dragging
• 38:34
  Speaker 1: through that atmosphere. The atmosphere would be spinning with the
• 38:37
  Speaker 1: combined Earth Moon system.
• 38:39
  Speaker 2: So if the Moon is made out of diamonds and
• 38:42
  Speaker 2: we're tidally logged, meaning that the atmosphere is spinning around
• 38:45
  Speaker 2: with the Moon, then you're saying it's possible. But even
• 38:48
  Speaker 2: if you're going super super fast like I said earlier,
• 38:50
  Speaker 2: wouldn't that blow away the atmosphere.
• 38:52
  Speaker 1: If you want to be really close, then you can't
• 38:54
  Speaker 1: be in geosynchronous orbit at the same time. But if
• 38:56
  Speaker 1: you were willing to get a little bit further away,
• 38:58
  Speaker 1: so the Moon was always above the same location in
• 39:01
  Speaker 1: the atmosphere, then it wouldn't be moving through our atmosphere,
• 39:05
  Speaker 1: so it wouldn't be blowing away all right.
• 39:08
  Speaker 2: So it sounds like the answer is, yes, it's possible.
• 39:10
  Speaker 1: I think it is possible. I think it's very unlikely
• 39:12
  Speaker 1: for it to happen, though. I think this wouldn't form naturally.
• 39:15
  Speaker 1: You'd have to like capture a moon that would have
• 39:17
  Speaker 1: to come at exactly the right orbit because it need
• 39:20
  Speaker 1: be perfectly circular. You know, if it goes like elliptical
• 39:23
  Speaker 1: at all, then it's going like in and out of
• 39:24
  Speaker 1: the atmosphere. It's going to be dragging. So this seems
• 39:27
  Speaker 1: very very unlikely to ever see in the universe, even
• 39:30
  Speaker 1: if you could make all the equations work.
• 39:33
  Speaker 2: Oh, I see you were saying another possibilities that maybe
• 39:35
  Speaker 2: this moon is more like a visitor every once in
• 39:37
  Speaker 2: a while, Like it's in a very elliptical orbit, and
• 39:40
  Speaker 2: sometimes it's really far away, and sometimes it comes really
• 39:42
  Speaker 2: close enough for you to maybe jump from one to
• 39:44
  Speaker 2: the other.
• 39:46
  Speaker 1: Now I was actually saying the opposite. I was saying
• 39:48
  Speaker 1: that in order for this to be stable, it have
• 39:49
  Speaker 1: to be almost perfectly circular orbit, because if it's elliptical
• 39:53
  Speaker 1: and it comes that close, then it's going to be
• 39:54
  Speaker 1: dragging through the atmosphere. What you want is a really
• 39:57
  Speaker 1: stable setup that never changes, and to get a the
• 40:00
  Speaker 1: circular orbit is very challenging. You basically have to capture
• 40:03
  Speaker 1: a moon in exactly the right situation.
• 40:06
  Speaker 2: Well, I guess you mean by like having a constant
• 40:09
  Speaker 2: bridge between the two planets, But maybe I mean I
• 40:11
  Speaker 2: haven't seen the show, but maybe this only happened once
• 40:13
  Speaker 2: in a while.
• 40:14
  Speaker 1: Yeah, I think, Like again, if you had a Kardashev
• 40:16
  Speaker 1: level three civilization, you might be able to engineer this,
• 40:18
  Speaker 1: But I wouldn't expect to find this naturally happening in
• 40:20
  Speaker 1: the universe.
• 40:21
  Speaker 2: What if you're a Kardashian level seven planet.
• 40:25
  Speaker 1: And your whole planet is made of chocolate cake.
• 40:28
  Speaker 2: You can have a lot of hot air perhaps, all right, well,
• 40:30
  Speaker 2: I guess he asked for Joe is Yeah, the show
• 40:33
  Speaker 2: got something that is plausible, right, Yeah.
• 40:35
  Speaker 1: If you are a Kardashian level seven civilization and you
• 40:38
  Speaker 1: have moons made of diamonds, if you got that much bling,
• 40:41
  Speaker 1: then yeah, you might be able to pull it off.
• 40:43
  Speaker 2: And things are kind of perfectly locked in and spinning
• 40:46
  Speaker 2: slow enough, and it's not spinning fast enough to blow
• 40:49
  Speaker 2: away your atmosphere. It's potentially possible.
• 40:51
  Speaker 1: It is potentially possible. Yeah, good luck, Joe.
• 40:54
  Speaker 2: Well, I guess the problem is he would have to
• 40:55
  Speaker 2: jump up a lot. All right, Well, that answers all
• 40:58
  Speaker 2: of our questions here today. Thanks to everyone who asks questions.
• 41:01
  Speaker 1: Thanks very much to everybody who shares your curiosity. It's
• 41:04
  Speaker 1: the reason why we do this podcast, and it's the
• 41:06
  Speaker 1: reason why science moves forward. It's our combined curiosity as
• 41:10
  Speaker 1: a human species that lets us explore the universe. So
• 41:13
  Speaker 1: thanks everyone for your support.
• 41:15
  Speaker 2: We hope you enjoyed that. Thanks for joining us. See
• 41:17
  Speaker 2: you next.
• 41:18
  Speaker 1: Time for more science and curiosity. Come find us on
• 41:25
  Speaker 1: social media, where we answer questions and post videos. We're
• 41:29
  Speaker 1: on Twitter, Discorg, Insta, and now TikTok. Thanks for listening
• 41:33
  Speaker 1: and remember that Daniel and Jorge Explain the Universe is
• 41:36
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• 41:45
  Speaker 1: your favorite shows.