Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 61.0158: Black holes, gold asteroids and gravitational waves in time!

Transcript

Listener Questions 61.0158: Black holes, gold asteroids and gravitational waves in time! · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Hey, Daniel, what's the latest news in physics?
• 0:10
  Speaker 2: We still don't know how anything works. Newsflash.
• 0:15
  Speaker 1: That's not really news, is it.
• 0:16
  Speaker 2: It's true every single morning.
• 0:19
  Speaker 1: There's been no new discoveries in the last week or so.
• 0:23
  Speaker 2: No, we learn stuff every year, but the fraction of
• 0:25
  Speaker 2: all knowledge we have remains approximately zero.
• 0:29
  Speaker 1: You mean compared to the infinity of the universe or
• 0:33
  Speaker 1: how much you're already forgetting due to age.
• 0:37
  Speaker 2: I think both are true. The denominator is infinite and
• 0:39
  Speaker 2: the numerator is true. It's decaying with time, Yes, exactly.
• 0:46
  Speaker 2: I may have reached my peak smartness a few years ago.
• 0:49
  Speaker 1: Oh, I think I reached my peak smartness like when
• 0:52
  Speaker 1: I was five.
• 0:53
  Speaker 2: Maybe you should have retired then, man.
• 0:56
  Speaker 1: I wish I could have. Yeah, I could have been
• 1:00
  Speaker 1: playing golf for the last fifty years.
• 1:05
  Speaker 2: There you go, folks. Advice to all you five year
• 1:07
  Speaker 2: olds out there, what's the advice? Be rich and retire earlier.
• 1:26
  Speaker 1: I am Jorge, a cartoonist and the author of Oliver's.
• 1:28
  Speaker 2: Great Big Universe. Hi, I'm Daniel. I'm a particle physicist
• 1:32
  Speaker 2: and the professor at UC Irvine, and I don't plan
• 1:35
  Speaker 2: to ever retire.
• 1:35
  Speaker 1: What do you mean you'll have to like drag you
• 1:37
  Speaker 1: out of your office at some point, or you plan
• 1:39
  Speaker 1: to die in your office.
• 1:42
  Speaker 2: I plan to die in this job, though I haven't
• 1:44
  Speaker 2: actually decided where physically that will be.
• 1:48
  Speaker 1: I guess, Yeah, I guess you can work from work
• 1:50
  Speaker 1: and die from home. I guess. But really you don't
• 1:54
  Speaker 1: plan to ever, you know, not do physics.
• 1:57
  Speaker 2: As so long as I can keep teaching and thinking,
• 1:59
  Speaker 2: then yeah, I'll keep doing it.
• 2:01
  Speaker 3: Mmmm.
• 2:03
  Speaker 1: You don't believe in like making room for the next
• 2:06
  Speaker 1: generation of physicists.
• 2:08
  Speaker 2: They're all retiring at five. They don't need jobs.
• 2:12
  Speaker 1: Well, you need room for the four year olds, you know.
• 2:15
  Speaker 1: But anyways, Welcome to our podcast Daniel and Jorge Explain
• 2:18
  Speaker 1: the Universe, a production of iHeartRadio.
• 2:20
  Speaker 2: In which we make the whole universe our problem, to
• 2:23
  Speaker 2: figure it out, to explain it to you, to understand
• 2:26
  Speaker 2: how it all works, to break it down into its
• 2:29
  Speaker 2: tiniest little bits and make it make sense if at
• 2:32
  Speaker 2: all possible.
• 2:33
  Speaker 1: That's right. We try to retire the ignorance that we
• 2:36
  Speaker 1: have about our universe and the beautiful cosmos that we
• 2:39
  Speaker 1: all live in, and we try to make headway into
• 2:43
  Speaker 1: your brain to help you understand how it all works
• 2:45
  Speaker 1: and what it all means about our existence.
• 2:49
  Speaker 2: And step one to figuring it out is understanding what
• 2:52
  Speaker 2: we don't know is examining the questions we still have
• 2:56
  Speaker 2: in our minds. What is it that we want to
• 2:58
  Speaker 2: figure out? What can the usion do we have about
• 3:01
  Speaker 2: how things are fitting together? What topics remain completely unexplored
• 3:06
  Speaker 2: and unknown. And it's not just professional physicists and five
• 3:09
  Speaker 2: year olds asking questions about the universe. It's everybody. And
• 3:12
  Speaker 2: we want to encourage you, everybody out there who's listening,
• 3:16
  Speaker 2: who is curious about the nature of the universe, to
• 3:19
  Speaker 2: ask questions. Ask them of yourself, and if you can't
• 3:21
  Speaker 2: figure them out, ask them of us. Write them to
• 3:24
  Speaker 2: Questions at Danielandjorge dot com and you'll get an answer.
• 3:28
  Speaker 1: Yeah, Because, as we said many times, the process of science,
• 3:30
  Speaker 1: the process of discovery and finding knowledge out there, starts
• 3:34
  Speaker 1: with questions, starts with people being curious about what they
• 3:38
  Speaker 1: see and what they think they don't understand.
• 3:40
  Speaker 2: And if you write to us with your questions, you'll
• 3:42
  Speaker 2: get a reply at least even if it's not a
• 3:44
  Speaker 2: complete answer, Because some of these questions nobody knows the
• 3:48
  Speaker 2: answer to, so all we can do is fast forward
• 3:50
  Speaker 2: you to the current forefront of human.
• 3:52
  Speaker 1: Ignorance, right, because sometimes asking a question of a scientist
• 3:56
  Speaker 1: helps them come up with new questions, right, or think
• 3:59
  Speaker 1: of questions and new ways in their research. Right. Has
• 4:02
  Speaker 1: anybody ever written you and you're like, WHOA, I never
• 4:04
  Speaker 1: thought about that before.
• 4:07
  Speaker 2: People have definitely written to me with questions I've never
• 4:10
  Speaker 2: had myself, ideas I've never thought of all the time,
• 4:14
  Speaker 2: I don't know that any of them have like actually
• 4:16
  Speaker 2: spurred new research.
• 4:19
  Speaker 1: Or maybe like a new way to think about what
• 4:21
  Speaker 1: you're doing.
• 4:22
  Speaker 2: I think sometimes the way people ask questions forces me
• 4:25
  Speaker 2: to think about things in a new way. Sure, and
• 4:27
  Speaker 2: you know, always the process of teaching and explaining forces
• 4:31
  Speaker 2: you to examine your own understanding and shore it up
• 4:34
  Speaker 2: and make connections you didn't make before. So this whole
• 4:37
  Speaker 2: podcast is like deep in my understanding of physics because
• 4:40
  Speaker 2: I'm forced to go out there and make connections and
• 4:42
  Speaker 2: find explanations for things that I was pretty sure I understood.
• 4:46
  Speaker 2: But when you go to explain it, you can always
• 4:48
  Speaker 2: find holes in your understanding.
• 4:50
  Speaker 1: Yeah, it's all the big conversations and we try to
• 4:53
  Speaker 1: make all of you listeners part of the conversation here
• 4:55
  Speaker 1: in our podcast, because sometimes in our episodes we answer
• 4:59
  Speaker 1: questions that we yet from listeners like you.
• 5:01
  Speaker 2: As are right. Sometimes the questions that come in through
• 5:04
  Speaker 2: the inbox are fascinating or tricky or complicated, or I
• 5:08
  Speaker 2: just think everybody might enjoy hearing the answer, so we
• 5:11
  Speaker 2: select some to answer here on the podcast. Thank you
• 5:14
  Speaker 2: to everybody who sends in your questions.
• 5:16
  Speaker 1: So today on the podcast, we'll be tackling listener questions.
• 5:24
  Speaker 1: Number sixty one, So Daniel, we're back to numbering these sequentially?
• 5:30
  Speaker 1: Or is this still a random number with a secret
• 5:33
  Speaker 1: code in it?
• 5:33
  Speaker 2: This is not a random number with secret code.
• 5:35
  Speaker 1: No.
• 5:36
  Speaker 2: I like to be sequential because when people write in
• 5:38
  Speaker 2: and I tell them we're going to answer it on
• 5:40
  Speaker 2: the podcast, I like to tell them which episode to
• 5:42
  Speaker 2: wait for, So numbers are useful for that, though I
• 5:44
  Speaker 2: suppose I could name them. Also, this could be the
• 5:46
  Speaker 2: elephant episode, or we're going to have a Polka Dot
• 5:49
  Speaker 2: episode or whatever. Those are just as arbitrary as numbers. Yeah,
• 5:54
  Speaker 2: or or like random numbers too?
• 5:55
  Speaker 1: Right? This could be sixty one point seven four five three?
• 5:59
  Speaker 2: Sure? Why not?
• 6:03
  Speaker 1: Aren't extractional names? That's right? Or you give me like
• 6:05
  Speaker 1: Elon Muskin and name things with weird symbols in them.
• 6:09
  Speaker 1: Then we'd have to struggle to pronounce them. Yeah, I
• 6:11
  Speaker 1: guess it is a podcast. We have to read things
• 6:13
  Speaker 1: out loud, so we could.
• 6:15
  Speaker 2: Just give them weird sounds then you know.
• 6:18
  Speaker 1: Oh, there you go. This is listener questions number and
• 6:23
  Speaker 1: then but then you have to also have to write them,
• 6:25
  Speaker 1: so that might be Yeah, maybe we should just stick
• 6:28
  Speaker 1: the numbers. Wow, it's like numbers are useful integers. Yeah. Yeah,
• 6:32
  Speaker 1: all right, so sixty one. I feel like we've been
• 6:34
  Speaker 1: increasing these numbers because I feel like we just a
• 6:37
  Speaker 1: few weeks ago we were at number forty three.
• 6:40
  Speaker 2: Man, We've been doing about one a week for a
• 6:42
  Speaker 2: while now because we got so many more questions coming in.
• 6:45
  Speaker 1: MMM. And so our first question comes from Augustine, and
• 6:49
  Speaker 1: his question is about the gravity of black holes.
• 6:54
  Speaker 4: Hello, Danny on her head, this is your friend. I
• 6:57
  Speaker 4: have a crazy idea. We know that the gravity and
• 7:00
  Speaker 4: a black hole is so strong that it will reap
• 7:03
  Speaker 4: apart matter or what we call sometimes stagratification. My understanding
• 7:07
  Speaker 4: is that this will happen all the way until even
• 7:10
  Speaker 4: particles are pull apart. My brain now is thinking, okay,
• 7:14
  Speaker 4: what about quarts. If I'm correct, the stronger you pull
• 7:17
  Speaker 4: apart a couple of quarks, the stronger the force. And
• 7:20
  Speaker 4: when we put in a force to pull them apart,
• 7:23
  Speaker 4: we give them force enough to create a new one,
• 7:26
  Speaker 4: and they are always in pairs. So now we have
• 7:28
  Speaker 4: like four age sixteen and close quarts. So it could
• 7:33
  Speaker 4: be possible that inside black holes we have an infinite
• 7:37
  Speaker 4: machine of creating quarts that might even be so many
• 7:41
  Speaker 4: at some point that we create a new universe inside
• 7:43
  Speaker 4: a black hole. Or even more, what if all that
• 7:48
  Speaker 4: energy of the black hole turns into just quarts and
• 7:52
  Speaker 4: making the black hole disappear? Thank you?
• 7:56
  Speaker 1: All right? Really fun question. Basically, I think he's asking
• 7:59
  Speaker 1: can he make spaghetti out of quarks?
• 8:03
  Speaker 2: Well, you know all spaghetti is made out of quarks
• 8:06
  Speaker 2: and electrons, so yeah, but this is not a cooking show. Now,
• 8:10
  Speaker 2: I think he's asking a really hard question about what
• 8:13
  Speaker 2: happens to particles inside a black hole.
• 8:17
  Speaker 1: Now we're talking about black hole, so I suspect the
• 8:19
  Speaker 1: answer will be we have no idea. But Augustine is
• 8:22
  Speaker 1: sort of a friend of the podcast, right.
• 8:24
  Speaker 2: Yeah, that's right. Augustine has his own Spanish language podcast,
• 8:27
  Speaker 2: which you should go and check out Kurt Gasidad Scientifica.
• 8:30
  Speaker 2: It's excellent and he and I have been in conversation
• 8:33
  Speaker 2: about physics for several years and I think he wrote
• 8:36
  Speaker 2: this in to try to stump me.
• 8:37
  Speaker 1: Cool, So go ahead and check out that podcast, even
• 8:40
  Speaker 1: if you don't speak Spanish. I imagine it's interesting.
• 8:44
  Speaker 2: You'll either learn physics or Spanish.
• 8:45
  Speaker 1: Yeah, are both?
• 8:47
  Speaker 5: Oh my goodness. Yeah, all right, So the question is interesting.
• 8:55
  Speaker 5: I think the question is like what happens to a
• 8:58
  Speaker 5: particle as it goes into a black hole, Because we've
• 9:01
  Speaker 5: talked about before this idea of spa gutification. As you
• 9:05
  Speaker 5: get near a black hole, the intensity of the gravitational
• 9:07
  Speaker 5: feel is so high that it sort of rips you apart.
• 9:09
  Speaker 2: Right, Yeah, that's exactly right. Gravity is very very powerful
• 9:13
  Speaker 2: near a black hole. And if you have a physical extent,
• 9:16
  Speaker 2: if you're not just a point particle, like if you're
• 9:18
  Speaker 2: a little blob, then gravity on one side is going
• 9:21
  Speaker 2: to be stronger than gravity on the other side, and
• 9:23
  Speaker 2: that means you're getting pulled harder on one side, and
• 9:26
  Speaker 2: that's equivalent to being pulled apart. So, for example, if
• 9:29
  Speaker 2: you are near a black hole, and your feet are
• 9:32
  Speaker 2: closer than your head, then the black hole is trying
• 9:34
  Speaker 2: to pull you into spaghetti. So it's like trying to
• 9:36
  Speaker 2: pull your head off of your body and your feet
• 9:38
  Speaker 2: off of your ankles, because it's pulling on those things differently.
• 9:42
  Speaker 2: That's where spaghettification comes from. It's the tidal forces of
• 9:45
  Speaker 2: the black hole, not directly the strength of the gravity
• 9:48
  Speaker 2: of the black hole, but the difference in its strength
• 9:50
  Speaker 2: as you get closer or further.
• 9:53
  Speaker 1: Right, because gravity depends on distance, right, gravity gets stronger
• 9:56
  Speaker 1: the closer you are to the source, just like gravity
• 10:00
  Speaker 1: stronger here on Earth than it is out there in space.
• 10:03
  Speaker 1: But sometimes the difference can be so big that it
• 10:06
  Speaker 1: can be enough to rip you apart.
• 10:08
  Speaker 2: That's right. Technically, the Earth is trying to rip you
• 10:10
  Speaker 2: apart because as you stand on the surface, the gravity
• 10:13
  Speaker 2: on your feet is stronger than the gravity on your head,
• 10:16
  Speaker 2: but that difference is much weaker than the internal strength
• 10:19
  Speaker 2: of your body, and so you're able to hold yourself together.
• 10:21
  Speaker 2: But that's not true near a black hole, because not
• 10:24
  Speaker 2: only is the gravity stronger, but the differences are stronger
• 10:27
  Speaker 2: because gravity gets weaker much faster with distance.
• 10:30
  Speaker 1: Right, So it's super intense when you get close to
• 10:32
  Speaker 1: a black hole, and so like if you were to
• 10:35
  Speaker 1: jump in head first, you would get ripped apart. Now,
• 10:38
  Speaker 1: I think Augustine's question is what happens to a particle?
• 10:41
  Speaker 1: Does a particle get pulled apart? And maybe let's start
• 10:44
  Speaker 1: with an atom, like would an atom get pulled apart?
• 10:46
  Speaker 2: Yeah, it's a great question, and there's a couple of
• 10:48
  Speaker 2: competing issues here. Like number one, the tile forces depend
• 10:52
  Speaker 2: on you having a physical extent. The further apart you are,
• 10:54
  Speaker 2: the greater the distance between one side of you and
• 10:56
  Speaker 2: the other, the greater the difference and gravitational force will be.
• 11:00
  Speaker 2: So if there's no difference between one side of you
• 11:02
  Speaker 2: and the other, if you're like a point particle, then
• 11:04
  Speaker 2: there's no title forces. So title forces only apply to
• 11:07
  Speaker 2: things that are not point particles. And you're right, an atom,
• 11:10
  Speaker 2: for example, it's not a point particle, and so in
• 11:12
  Speaker 2: principle an atom could get pulled apart. But atoms are
• 11:15
  Speaker 2: so tiny, really really small, that the title forces are
• 11:20
  Speaker 2: going to be super duper tiny compared to like the
• 11:22
  Speaker 2: strength of the nuclear forces holding it together.
• 11:25
  Speaker 1: Right, I guess it's not just about how much gravity
• 11:27
  Speaker 1: there is it's about, like you said, the slope of
• 11:31
  Speaker 1: the gravity, or like the intensity of or how quickly
• 11:34
  Speaker 1: gravity is changing, Like the difference between one end of
• 11:36
  Speaker 1: the atom and the other end of the atom has
• 11:39
  Speaker 1: to be large enough to overcome those forces. But is
• 11:42
  Speaker 1: that possible? Though? It is kind of possible, isn't it?
• 11:44
  Speaker 2: In principle it is if you take the general relativistic
• 11:47
  Speaker 2: view of black holes a singularity, then as you get
• 11:50
  Speaker 2: closer and closer to the singularity, the curvature is just increasing.
• 11:54
  Speaker 2: And you might argue, well, the curvature has to be
• 11:56
  Speaker 2: crazy high for the title forces to compete with the
• 12:00
  Speaker 2: ternal strength of an atom. But then you can just
• 12:02
  Speaker 2: keep moving closer to the singularity to get arbitra early
• 12:05
  Speaker 2: strong gravity. And so, in principle, somewhere inside a black hole,
• 12:09
  Speaker 2: if there is a singularity there, you can get close
• 12:11
  Speaker 2: enough to it that the tidal forces should overcome the
• 12:15
  Speaker 2: strength of the bonds holding an atom together, and an
• 12:17
  Speaker 2: atom would get spaghetified.
• 12:20
  Speaker 1: So it wouldn't happen outside or as it goes in,
• 12:22
  Speaker 1: it would have to happen way in there.
• 12:25
  Speaker 2: Yeah, I did the calculation once, and outside the black
• 12:28
  Speaker 2: hole the gravity is not strong enough to spaghetify atoms.
• 12:31
  Speaker 2: But inside Again, if there is a singularity and we
• 12:33
  Speaker 2: don't know that there is, then in principle you could
• 12:36
  Speaker 2: get close enough inside.
• 12:38
  Speaker 1: Well, doesn't it depend on the size of the black hole,
• 12:41
  Speaker 1: Like the heavier and more intense the black hole is,
• 12:45
  Speaker 1: the less close you have to get to the center
• 12:48
  Speaker 1: to maybe rip apart an atom. Hmm.
• 12:50
  Speaker 2: Although if you can get arbitrary close then it doesn't
• 12:52
  Speaker 2: really matter what the mass of the black hole is
• 12:54
  Speaker 2: because you're decreasing that distance parameter. But yeah, for larger
• 12:57
  Speaker 2: black holes you don't have to get as close.
• 13:00
  Speaker 1: Did it even get to the center? Like, doesn't time
• 13:02
  Speaker 1: stop as you get to the edge or the surface
• 13:04
  Speaker 1: of a black hole?
• 13:06
  Speaker 2: Yeah, that's a little bit tricky. That depends on who's looking.
• 13:09
  Speaker 2: If you're in the outside of a black hole and
• 13:10
  Speaker 2: you're watching things fall in, then time slows down for
• 13:14
  Speaker 2: those objects according to you, and you never see them
• 13:16
  Speaker 2: fall into the black hole. But for the object itself,
• 13:19
  Speaker 2: time proceeds normally and they just fall in past the
• 13:22
  Speaker 2: event horizon and proceed towards the singularity and reach it
• 13:26
  Speaker 2: in finite time. General relativity is very tricky when it
• 13:29
  Speaker 2: comes to whose time we're talking about.
• 13:31
  Speaker 1: Right, But to the rest of the universe, it would
• 13:33
  Speaker 1: never happen.
• 13:34
  Speaker 2: Right, for the rest of the university, it would never
• 13:36
  Speaker 2: happen if it's the last thing you throw into the
• 13:38
  Speaker 2: black hole. As you approach the black hole, the black
• 13:41
  Speaker 2: holes of vent horizon actually grows out to meet you
• 13:44
  Speaker 2: because the power, the gravitational energy of the black hole
• 13:47
  Speaker 2: increases before the object crosses the event horizon. It's not
• 13:50
  Speaker 2: like it has to physically eat it and then it
• 13:52
  Speaker 2: pops out to be larger. So if you toss something
• 13:55
  Speaker 2: like a banana towards a black hole, it's event horizon
• 13:57
  Speaker 2: grows out or meet the banana, but never reaches it
• 14:00
  Speaker 2: unless you then throw an orange. That orange will pull
• 14:03
  Speaker 2: the event horizon out even further past the banana. So
• 14:06
  Speaker 2: the last thing to get thrown into a black hole
• 14:08
  Speaker 2: never actually reaches it, but earlier stuff will.
• 14:11
  Speaker 1: Will it like will the banana actually reach the center
• 14:13
  Speaker 1: of the black hole? Or are things frozen in time
• 14:16
  Speaker 1: inside the black hole?
• 14:18
  Speaker 2: Well, you can only answer these questions from the point
• 14:20
  Speaker 2: of view of some observer, and there's no observer on
• 14:23
  Speaker 2: the outside. They can see the inside of the black
• 14:25
  Speaker 2: hole from within the black hole, the banana reaches a singularity.
• 14:28
  Speaker 2: But I feel like Augustine is asking a question about
• 14:31
  Speaker 2: the interplay between the tidal forces and the strong nuclear
• 14:35
  Speaker 2: force inside that atom.
• 14:37
  Speaker 1: Right right, Well, we said that it would maybe pull
• 14:40
  Speaker 1: apart an atom and maybe even a cord, but only
• 14:43
  Speaker 1: if it gets close to the singularity. I guess. I
• 14:45
  Speaker 1: mean then now the question sort of hinges like, will
• 14:48
  Speaker 1: it ever get close to that singularity?
• 14:50
  Speaker 2: According to general relativity, things will approach the singularity, And
• 14:53
  Speaker 2: Augustine is asking about this interesting question that's trying to
• 14:56
  Speaker 2: balance this power of the black hole to pull basically
• 15:00
  Speaker 2: anything apart if it approaches a singularity, and the strong force,
• 15:03
  Speaker 2: which has this bizarre behavior that if you pull things apart,
• 15:06
  Speaker 2: it pops new particles out of the vacuum. And I
• 15:09
  Speaker 2: think he's wondering whether that's effectively creating an infinite amount
• 15:12
  Speaker 2: of mass.
• 15:13
  Speaker 1: Mmm, oh, I see, all right, let's dig into his
• 15:15
  Speaker 1: specific scenario. So now we're imagining it that a quark
• 15:19
  Speaker 1: somehow gets inside of a black hole and it does
• 15:22
  Speaker 1: make it close enough to this singularity that they would
• 15:25
  Speaker 1: get pulled apart, or.
• 15:27
  Speaker 2: I think imagine two quarks like you have a quark
• 15:29
  Speaker 2: antiquark pair. They're bound together into something like a pion,
• 15:33
  Speaker 2: or maybe you have three quarks within a proton, and
• 15:35
  Speaker 2: then those get pulled apart by the singularity. And when
• 15:38
  Speaker 2: those get pulled apart, there's now energy in that bond
• 15:41
  Speaker 2: which gets turned into mass in the form of new quarks. Mmm.
• 15:45
  Speaker 1: So then what would happen? So now you have a
• 15:47
  Speaker 1: third quark that suddenly appears next to the other two.
• 15:51
  Speaker 2: Yeah, actually you're going to get another pair of quarks.
• 15:53
  Speaker 2: So if you start, for example, with a quark antiquark pair,
• 15:56
  Speaker 2: and you pull them apart outside a black hole or
• 15:58
  Speaker 2: inside a black hole, with going to happen is that
• 16:00
  Speaker 2: there's a huge amount of energy stored in the strong
• 16:03
  Speaker 2: force between the two quarks. Because remember the strong force
• 16:05
  Speaker 2: is really weird, and the force between them doesn't decrease
• 16:09
  Speaker 2: with distance. As you increase the distance between the cork
• 16:12
  Speaker 2: and antiquark pair, the amount of energy in that bond
• 16:14
  Speaker 2: becomes enormous, and the universe prefers to convert that energy
• 16:18
  Speaker 2: back into mass, and it creates a new cork anti
• 16:20
  Speaker 2: cork pair, effectively reducing those distances. So you have like
• 16:24
  Speaker 2: cork antiquark now turns into cork antiquork cork antiquark.
• 16:28
  Speaker 1: So like they multiplied or they just sort of like
• 16:31
  Speaker 1: divided the energy between two.
• 16:32
  Speaker 2: Pairs, because I'm not sure what the difference is. Like,
• 16:35
  Speaker 2: you have one configuration with a lot of energy in
• 16:37
  Speaker 2: the bond. The next configuration, the one the universe prefers,
• 16:41
  Speaker 2: is to have lower energy in the bonds and have
• 16:43
  Speaker 2: more energy in the masses. The reason the universe prefers
• 16:46
  Speaker 2: that is that there's more possible configurations. That way, you
• 16:49
  Speaker 2: have more particles, they can get moved around a lot.
• 16:52
  Speaker 2: In general, the universe prefers to spread energy out because
• 16:55
  Speaker 2: it allows for more options. It's like an effective entropy.
• 16:58
  Speaker 1: Okay, so then the black hole would split the cork
• 17:01
  Speaker 1: pair and make four quarks. And now what happens next.
• 17:05
  Speaker 1: Then those four quarks would fall into the black hole.
• 17:07
  Speaker 1: Would they also get split?
• 17:09
  Speaker 2: Yep, those get split, and then you get more quarks,
• 17:11
  Speaker 2: and then those get split and you get more quarks.
• 17:13
  Speaker 1: But at some point, don't you start to dilute the energy?
• 17:17
  Speaker 1: Isn't each subsequent pair of quarks don't they have less
• 17:20
  Speaker 1: energy in their bonds?
• 17:22
  Speaker 2: Yeah? Exactly, And that's what happens in real life, like,
• 17:24
  Speaker 2: we do this at the Large Hadron Collider all the time.
• 17:26
  Speaker 2: We don't have a black hole yet, hopefully that we're
• 17:30
  Speaker 2: aware of. The lawyers require me to say. We create
• 17:33
  Speaker 2: quarks in it at quarks all the time, and we
• 17:35
  Speaker 2: create them in a way that they're flying apart. They
• 17:37
  Speaker 2: have a lot of velocity away from each other, and
• 17:39
  Speaker 2: so what happens is you get new pairs of quarks.
• 17:41
  Speaker 2: That energy is converted into mass, and eventually you got
• 17:44
  Speaker 2: a huge number of quark antiquark pairs and they're flying
• 17:47
  Speaker 2: away from each other, so that energy, that velocity gets
• 17:50
  Speaker 2: turned into mass. Effectively, what's happening here is something similar,
• 17:54
  Speaker 2: except you have gravitational energy. You're using the gravitational energy
• 17:59
  Speaker 2: of the black hole to basically pull the quarks apart.
• 18:02
  Speaker 2: That kinetic energy then gets turned into mass. So you're
• 18:05
  Speaker 2: turning the gravitational energy the black hole into mass.
• 18:09
  Speaker 1: So you're just sort of like churning energy around. You're
• 18:11
  Speaker 1: not creating new energy, you're not destroying energy. You know,
• 18:15
  Speaker 1: the energy still stays within the black hole. It's just that,
• 18:18
  Speaker 1: according to your theories, there's going to be a lot
• 18:20
  Speaker 1: of weird slashing around in there.
• 18:23
  Speaker 2: Yeah, exactly, and Augustine is wondering, like, does this turn
• 18:26
  Speaker 2: into an infinite amount of energy or where does this
• 18:29
  Speaker 2: energy come from? And the energy really comes from within
• 18:32
  Speaker 2: the black hole. It's just the gravitational energy of the
• 18:35
  Speaker 2: black hole. It's just like asking, hey, if you have
• 18:38
  Speaker 2: a particle near the edge of a black hole, doesn't
• 18:40
  Speaker 2: it accelerate as it gets towards the center of the
• 18:42
  Speaker 2: black hole? Where does that energy come from? That energy
• 18:46
  Speaker 2: just comes from the gravitational energy of the black hole.
• 18:49
  Speaker 2: It's converting the potential energy of the black hole into
• 18:51
  Speaker 2: kinetic energy of this particle. The thing about the black
• 18:54
  Speaker 2: hole is that doesn't change the overall energy of the
• 18:57
  Speaker 2: black hole. It still has the same total energy, which
• 18:59
  Speaker 2: is what in the end controls its gravitational power. So
• 19:02
  Speaker 2: it doesn't really matter what you do within the black hole.
• 19:05
  Speaker 2: Do you have quarks? Did you have the energy in
• 19:07
  Speaker 2: the bonds? You have it in the gravitational potential energy.
• 19:09
  Speaker 2: As you say, it's just sloshing around inside the black hole.
• 19:13
  Speaker 1: But do you get like an infinite number of quarks
• 19:15
  Speaker 1: being made or is there at some point does it
• 19:17
  Speaker 1: stop popping off these new quarks or is it that
• 19:20
  Speaker 1: at some point. You know, the courts you create have
• 19:22
  Speaker 1: so little energy to them that there's just not enough
• 19:25
  Speaker 1: to make new quarks.
• 19:26
  Speaker 2: It's a great question, and we don't actually know the
• 19:28
  Speaker 2: answer to it. In this simplistic model that I've drawn out,
• 19:30
  Speaker 2: where you have like a pure general relativity black hole
• 19:33
  Speaker 2: with an actual singularity in it, and then you have
• 19:36
  Speaker 2: these particles, you get an infinite number of quarks because
• 19:39
  Speaker 2: as you approach the singularity, there's always a place where
• 19:42
  Speaker 2: the new quarks are going to get rid apart to
• 19:44
  Speaker 2: make new quarks, to make more quarks. But the problem
• 19:46
  Speaker 2: there the infinity in the number of quarks comes from
• 19:48
  Speaker 2: the infinity in the singularity, which we don't think is physical.
• 19:52
  Speaker 2: So the real answer depends on knowing what's actually going
• 19:55
  Speaker 2: on inside a black hole, and the infinity in this
• 19:57
  Speaker 2: answer comes from the infinity and assuming that it's a singularity,
• 20:00
  Speaker 2: which is probably not true.
• 20:02
  Speaker 3: Mmm.
• 20:03
  Speaker 1: I see, so you're saying the answer is that we
• 20:05
  Speaker 1: don't know.
• 20:05
  Speaker 2: We didn't know.
• 20:09
  Speaker 1: We could just skipped the last twenty minutes. Daniel just
• 20:11
  Speaker 1: comes with my answer.
• 20:13
  Speaker 2: No, you were totally correct right off the bat, because
• 20:16
  Speaker 2: we don't know how gravity and quantum particles interact we
• 20:19
  Speaker 2: don't even know how to calculate gravity for quantum particles
• 20:21
  Speaker 2: that have uncertain locations. So the right answer depends on
• 20:24
  Speaker 2: figuring out quantum gravity, which we have not yet done.
• 20:27
  Speaker 1: Right, We don't even know if it'll make it to
• 20:29
  Speaker 1: the center, right, Like, we don't really know what happens
• 20:31
  Speaker 1: even beyond the event horizon.
• 20:33
  Speaker 2: Right, Yeah, exactly right. There are some theories that black
• 20:35
  Speaker 2: holes have no center, have no interiors, all just smeared
• 20:38
  Speaker 2: on this sphericle event horizon, and there is nothing in
• 20:42
  Speaker 2: the bulk. All the information is just encoded on a
• 20:44
  Speaker 2: two D surface, that the black hole is not actually
• 20:47
  Speaker 2: part of our universe.
• 20:48
  Speaker 1: Sounds like maybe the next question is not can you
• 20:50
  Speaker 1: make spaghetti out of quarks? Is can you make smir
• 20:52
  Speaker 1: out of quarts?
• 20:57
  Speaker 2: All Schmeer has quarts in it, and in fact, the
• 20:59
  Speaker 2: Germans have a kind of spread called quark, which is
• 21:02
  Speaker 2: some kind of yogrity spread.
• 21:05
  Speaker 1: It sounds like the Germans know the answer to this question.
• 21:08
  Speaker 2: Perhaps the answer is probably one really long German word.
• 21:12
  Speaker 1: Are there a German science podcast you've been on that
• 21:15
  Speaker 1: maybe could help us illuminate the topic? Here, you've been
• 21:20
  Speaker 1: on nine of them.
• 21:25
  Speaker 2: I'm going to leave you in the quantum superposition of
• 21:27
  Speaker 2: thinking that was nine englishman. I think that was just
• 21:31
  Speaker 2: a bad pun. I think it was a pretty good pun,
• 21:34
  Speaker 2: or a pretty good pun.
• 21:35
  Speaker 1: All right, Well, thank you Augustine for what do you
• 21:37
  Speaker 1: do in your podcast and also for sending us this question.
• 21:40
  Speaker 1: So now let's get to our next questions. We have
• 21:43
  Speaker 1: one here about golden asteroids and one about the effects
• 21:47
  Speaker 1: of gravitational waves on time, So let's get to those.
• 21:51
  Speaker 1: But first let's take a quick break where we're answering
• 22:07
  Speaker 1: listener questions here today on podcast number sixty one point
• 22:12
  Speaker 1: zero zero zero zero zero right now? Does a podcast
• 22:14
  Speaker 1: number have those decimals or is it a pure integer?
• 22:17
  Speaker 2: I think it gets rounded by our heart processing system.
• 22:22
  Speaker 1: I didn't know we had a process for rounding titles.
• 22:27
  Speaker 1: All right. Our next question comes from Mike, who comes
• 22:29
  Speaker 1: from Brooklyn.
• 22:31
  Speaker 2: Hi, Daniel, and Jorge.
• 22:33
  Speaker 6: Is it possible that somewhere in the universe there are
• 22:36
  Speaker 6: asteroids as big as our moon, made entirely of rare
• 22:39
  Speaker 6: metals such as gold or silver. How large an object
• 22:43
  Speaker 6: or system of such objects could there be? Thanks for
• 22:46
  Speaker 6: considering this question. You guys are the best and Katie
• 22:50
  Speaker 6: and Kelly are awesome co hosts too from Mike and Brooklyn.
• 22:55
  Speaker 1: All right, thank you, Mike. Pretty cool question. I guess
• 22:58
  Speaker 1: the question is could you have a giant gold asteroid
• 23:02
  Speaker 1: out there?
• 23:03
  Speaker 2: Yeah, and he wants a giant gold moon.
• 23:06
  Speaker 1: Moon or a gold planet. Is that possible?
• 23:11
  Speaker 2: I love the idea. Well it's a golden idea.
• 23:14
  Speaker 1: Well, let's dig into it. What are the chances that
• 23:18
  Speaker 1: pure gold things are out there.
• 23:20
  Speaker 2: There's definitely a lot of gold out there in the universe,
• 23:22
  Speaker 2: Like there is a lot of gold in the Earth,
• 23:25
  Speaker 2: and there are big blobs of gold in some sort
• 23:27
  Speaker 2: of like big heavy metallic asteroids. But the process by
• 23:31
  Speaker 2: which gold is made in the universe makes it, I think,
• 23:34
  Speaker 2: pretty unlikely to have like just a huge gold bar
• 23:37
  Speaker 2: floating out there in space.
• 23:39
  Speaker 1: Hmmm, what do you mean? How is gold made in
• 23:41
  Speaker 1: the universe?
• 23:42
  Speaker 2: Well, gold is a very heavy element, like many very
• 23:44
  Speaker 2: rare valuable elements, and it's so heavy that it can't
• 23:48
  Speaker 2: actually be made inside stars.
• 23:50
  Speaker 1: Right.
• 23:50
  Speaker 2: The brief history of the universe is that we started
• 23:52
  Speaker 2: out with almost all hydrogen, and then we formed stars
• 23:55
  Speaker 2: after a few hundred million years. Those stars are hot
• 23:58
  Speaker 2: and dense enough to do fusion which can make heavier elements,
• 24:01
  Speaker 2: but only up to about iron. Up to about iron,
• 24:04
  Speaker 2: when you fuse nuclei, you actually gain energy that releases energy.
• 24:08
  Speaker 2: It powers the star above iron. It costs energy to
• 24:11
  Speaker 2: do fusion, so you're cooling the star, you're consuming the
• 24:14
  Speaker 2: star's energy. So stars basically make elements up to about iron.
• 24:19
  Speaker 2: Heavier things than that require more specialized conditions, like the
• 24:22
  Speaker 2: collisions of neutron stars or supernova collapses that briefly create
• 24:27
  Speaker 2: the conditions necessary to consume that energy and make the
• 24:31
  Speaker 2: heavier elements m.
• 24:33
  Speaker 1: So you need a star to explode to make anything
• 24:34
  Speaker 1: above iron.
• 24:35
  Speaker 2: Anything above iron is made either in supernova so star
• 24:38
  Speaker 2: explosions or in neutron star collisions. And it used to
• 24:42
  Speaker 2: be that we thought it was mostly supernova but then
• 24:44
  Speaker 2: recently observations of neutron star collisions have sort of tilted
• 24:48
  Speaker 2: the balance, and now we think that probably most of
• 24:50
  Speaker 2: the gold in the universe is made in neutron star collisions.
• 24:54
  Speaker 2: How do we do that, Well, some neutron star collisions
• 24:56
  Speaker 2: they've observed in a couple of different ways, Like they've
• 24:58
  Speaker 2: seen the gravitational waves generated by these really intense massive
• 25:03
  Speaker 2: objects orbiting around each other and then eventually colliding, and
• 25:06
  Speaker 2: they also observed them astronomically, like they saw light from
• 25:10
  Speaker 2: the same event, and from that light they can measure
• 25:12
  Speaker 2: like how much gold was created, because gold, like every
• 25:15
  Speaker 2: other element, has a very special atomic fingerprint. It tends
• 25:19
  Speaker 2: to glow in certain wavelengths and give off light in
• 25:21
  Speaker 2: certain wavelengths. So they're able to measure the amount of
• 25:23
  Speaker 2: golden clouds around this neutron star collision by looking at
• 25:27
  Speaker 2: the light that came from it. It's this new era
• 25:29
  Speaker 2: of multi messenger astronomy where you see the same event
• 25:32
  Speaker 2: in two different sort of channels, and our understanding is
• 25:35
  Speaker 2: still pretty fuzzy, but it suggests that like huge amounts
• 25:38
  Speaker 2: of gold were made, like more than the mass of
• 25:41
  Speaker 2: the Earth is made in each of these collisions.
• 25:43
  Speaker 1: But I guess maybe a question is is it only
• 25:46
  Speaker 1: gold that gets made or is it all materials above,
• 25:51
  Speaker 1: you know, iron, get made in an equal amount or
• 25:55
  Speaker 1: is it sort of random.
• 25:56
  Speaker 2: It's not just gold that gets made. It's all these
• 25:58
  Speaker 2: heavy elements get made these kind of special events in
• 26:01
  Speaker 2: supernova implusions, in neutron star collisions, and it's definitely not equal, right,
• 26:06
  Speaker 2: Some of these things are easier to make because the
• 26:08
  Speaker 2: pathways for them to happen. Some of these things are
• 26:10
  Speaker 2: very very unstable, so even though you make them, they
• 26:12
  Speaker 2: disappear very rapidly and then decay down into other stuff.
• 26:16
  Speaker 2: We had a whole episode recently with Kelly about which
• 26:18
  Speaker 2: elements are more common in the universe, where we dig
• 26:21
  Speaker 2: into the science and the chemistry of that. But basically,
• 26:23
  Speaker 2: you're making everything possible and then only the stable stuff
• 26:26
  Speaker 2: sticks around very long.
• 26:28
  Speaker 1: Now, I know that in a supernova, I think what
• 26:30
  Speaker 1: happens is the inside of the star collapses and then
• 26:34
  Speaker 1: it bounces, and there's this huge shockwave. And as the
• 26:36
  Speaker 1: shockwave goes through the rest of the star, the outside
• 26:38
  Speaker 1: of the star, it basically squeezes things so much in
• 26:42
  Speaker 1: this shockwave that the neutrons and protons fuse together to
• 26:45
  Speaker 1: make these heavy elements.
• 26:47
  Speaker 2: Right mm hmm, yeah, that's right. You need very high
• 26:50
  Speaker 2: pressure and very high temperature in order to create these
• 26:53
  Speaker 2: heavy elements, and you need a lot of energy because
• 26:55
  Speaker 2: these processes absorb energy rather than creating it.
• 26:59
  Speaker 1: Now, is there a sort of a a propensity or
• 27:01
  Speaker 1: a tendency as the shockwave goes out to have phases
• 27:06
  Speaker 1: where it's making a lot of gold and then suddenly
• 27:09
  Speaker 1: it's making a ton of other elements and then suddenly
• 27:11
  Speaker 1: or is it all random all the time?
• 27:13
  Speaker 2: Yeah, that's a great question. It's not something we understand.
• 27:15
  Speaker 2: It's an area of current research exactly how that's happening.
• 27:19
  Speaker 2: This shockwave physics is very complicated because it's very sensitive
• 27:22
  Speaker 2: to a lot of the details. It's not like, on
• 27:24
  Speaker 2: average it ends up doing the same thing a little
• 27:27
  Speaker 2: bit hotter, a little bit colder, or the shockwave starts
• 27:29
  Speaker 2: here or starts there, and the conditions of the shockwave change.
• 27:33
  Speaker 2: So that's something people are working on right now. They
• 27:35
  Speaker 2: have these really complicated models of what's going on inside supernova.
• 27:38
  Speaker 1: So we don't know yet, but I imagine maybe the
• 27:42
  Speaker 1: conditions to make gold are maybe different than the conditions
• 27:44
  Speaker 1: to make lead or titanium, right, And so I imagine that
• 27:49
  Speaker 1: it's not just all random all the time. Maybe you know,
• 27:52
  Speaker 1: as the explosion goes out, maybe you get the conditions
• 27:54
  Speaker 1: for gold, and then suddenly the conditions change for something else, etc.
• 27:58
  Speaker 2: But it's also not clear that the condition are the
• 28:00
  Speaker 2: same across the whole star. The explosion might start in
• 28:03
  Speaker 2: one spot and then end in another. Spot, and so
• 28:06
  Speaker 2: you might simultaneously have different conditions across different parts of
• 28:09
  Speaker 2: the surface.
• 28:10
  Speaker 1: But I imagine there has to be a reason that
• 28:12
  Speaker 1: you find gold nuggets on Earth, right, like all those atoms,
• 28:17
  Speaker 1: those trillions of atoms in a gold nugget must have
• 28:19
  Speaker 1: been made at the same time. Or do you think
• 28:21
  Speaker 1: they were made separately in different phases and somehow they
• 28:24
  Speaker 1: got together at some point.
• 28:26
  Speaker 2: I think the formation of the gold that we find
• 28:28
  Speaker 2: here on Earth doesn't reflect how it is actually made
• 28:32
  Speaker 2: in the star. I think it more reflects the differentiation
• 28:34
  Speaker 2: process and the geology, the rock formation of what's happening
• 28:38
  Speaker 2: here on Earth. As the Earth cools. I think likely anyway,
• 28:42
  Speaker 2: gold made in these neutron stars comes out as a
• 28:44
  Speaker 2: huge fine spray, a mist, which then gets mixed out
• 28:48
  Speaker 2: into the universe, and you know these little granules that
• 28:50
  Speaker 2: then spread out. I don't think gold nuggets are formed
• 28:54
  Speaker 2: and then survive in that shape to be dug up.
• 28:56
  Speaker 1: You're saying, maybe it all gets made as dust, gold dust,
• 29:00
  Speaker 1: and then when the Earth was like a big ball
• 29:02
  Speaker 1: of lava, maybe gold doest sprinkle throughout it. The gold
• 29:06
  Speaker 1: doest somehow, you know, settled in the same spot and
• 29:09
  Speaker 1: then stuck together.
• 29:11
  Speaker 2: Yeah, that's exactly right. The Earth is formed from a
• 29:13
  Speaker 2: huge blob of gas and dust. Some of that is
• 29:16
  Speaker 2: little flecks of gold or heavier elements, and then as
• 29:19
  Speaker 2: that gets squeezed together into a planet, it gets hot, right,
• 29:21
  Speaker 2: and it gets molten, and then you have all sorts
• 29:24
  Speaker 2: of processes that happen. Like some of these elements are
• 29:26
  Speaker 2: called iron loving elements. They like to mix with iron
• 29:29
  Speaker 2: and they flow with the iron. So then as the
• 29:32
  Speaker 2: Earth is cooling, it differentiates and some of the heavy
• 29:35
  Speaker 2: things sink and some of the lighter things rise. And
• 29:38
  Speaker 2: the flow of those molten rocks and elements and oxides
• 29:40
  Speaker 2: and all sorts of complicated stuff determines where things end up.
• 29:44
  Speaker 2: And the big blobs that's why, like you get veins
• 29:46
  Speaker 2: of heavy metals or veins of copper here and there
• 29:49
  Speaker 2: comes from those molten flows, which then cool.
• 29:52
  Speaker 1: But you're saying that out there in space in the supernova,
• 29:55
  Speaker 1: we're not sure if these things get made as dust
• 29:58
  Speaker 1: or as layer chunks.
• 30:00
  Speaker 2: Yeah, we're not sure. I mean, I think it's most
• 30:02
  Speaker 2: likely because it's just the chaos and they energy this
• 30:05
  Speaker 2: process that it's spread out in terms of tiny granules,
• 30:08
  Speaker 2: But I don't know what the maximum size would be.
• 30:10
  Speaker 2: It's certainly possible that you get big ingots or even
• 30:14
  Speaker 2: enormous blobs. I mean, you can't rule out the possibility
• 30:16
  Speaker 2: that you're making like a blob the size of the
• 30:18
  Speaker 2: Los Angeles of pure gold. You know, quantum mechanically, anything
• 30:22
  Speaker 2: as possible.
• 30:22
  Speaker 1: So in principle it could be What about these neutron
• 30:25
  Speaker 1: star collisions. Is the mechanism the same like a shockwave
• 30:28
  Speaker 1: or do things it made from the soup of neutrons
• 30:32
  Speaker 1: and quarts that make up the stars.
• 30:34
  Speaker 2: Well, there definitely is a collision there and that creates
• 30:36
  Speaker 2: a shockwave through both neutron stars. Then they settle down
• 30:39
  Speaker 2: to form one bigger neutron star or a black hole
• 30:42
  Speaker 2: more likely if they're over the threshold now for a
• 30:44
  Speaker 2: neutron star to be stable, but we really don't understand
• 30:48
  Speaker 2: what's inside a neutron star and how that all works.
• 30:50
  Speaker 2: So we know that there's a process there that's capable
• 30:53
  Speaker 2: of creating these heavy elements, but we do not have
• 30:55
  Speaker 2: a detailed understanding of it. We don't even understand a
• 30:58
  Speaker 2: single stable neutron star, not to mention like two of
• 31:00
  Speaker 2: them smashing into each other, having complex shock waves bouncing
• 31:04
  Speaker 2: around inside.
• 31:05
  Speaker 1: Because I think neutron stars are basically like a giant
• 31:08
  Speaker 1: ball of soup of neutrons and quarks, right, So, I
• 31:12
  Speaker 1: mean it seems possible you could just scoop up some
• 31:14
  Speaker 1: neutrons or quarks and then damn you certainly get a
• 31:17
  Speaker 1: giant gold planet.
• 31:19
  Speaker 2: Well, neutron star is a little bit more complicated than that,
• 31:21
  Speaker 2: Like near the outside, they actually have a crust which
• 31:23
  Speaker 2: you can have some protons and electrons in it. Then
• 31:25
  Speaker 2: then we think there's probably a layer there's pure neutrons,
• 31:28
  Speaker 2: and below that we just don't really know, Like below
• 31:31
  Speaker 2: that probably doesn't even make sense to call it neutrons,
• 31:34
  Speaker 2: As you say, it's just like a soup of quarks,
• 31:36
  Speaker 2: like a quark gluon plasma, where the energy and the
• 31:38
  Speaker 2: density are so high that the whole idea of a
• 31:40
  Speaker 2: neutron doesn't really make sense. It's like a drop in
• 31:43
  Speaker 2: an ocean, right, you don't really call it a drop anymore.
• 31:46
  Speaker 2: And then below that we think probably there are new
• 31:48
  Speaker 2: states of matter, nuclear pasta or other weird exotic forms
• 31:52
  Speaker 2: of matter that only exist under these very high pressure
• 31:54
  Speaker 2: and temperature situations. So it's not just a ball of neutrons,
• 31:57
  Speaker 2: though there's plenty of neutrons there to play with.
• 32:00
  Speaker 1: H all right, So it sounds sort of unlikely that
• 32:03
  Speaker 1: in our universe there have foreign moons or big asteroids
• 32:06
  Speaker 1: of just pure gold. Right. Although there aren't there giant
• 32:09
  Speaker 1: asteroids of pure iron out there.
• 32:12
  Speaker 2: There are giant asteroids out there which are very metallic.
• 32:15
  Speaker 2: Like in our Solar system. We have a bunch of
• 32:17
  Speaker 2: different kinds of asteroids. There's like C type that have
• 32:20
  Speaker 2: a lot of water and ice in them, but there
• 32:23
  Speaker 2: is a kind called S type, which is a lot
• 32:25
  Speaker 2: of metal. For example, like a ten meters wide asteroid
• 32:28
  Speaker 2: might have like six hundred thousand kilograms of metal, including
• 32:33
  Speaker 2: like fifty kilograms of platinum and gold. And then there's
• 32:36
  Speaker 2: the M type, which are more rare, but they have
• 32:39
  Speaker 2: like ten times as much metal. So yes, these asteroids
• 32:42
  Speaker 2: do have a lot of metal in them, but they
• 32:44
  Speaker 2: start from the same basic materials as the Earth, and
• 32:47
  Speaker 2: so roughly they have like a random scoop of the
• 32:49
  Speaker 2: Solar system. It's just on the Earth, a lot of
• 32:52
  Speaker 2: this stuff is sunk down into the core and so
• 32:54
  Speaker 2: it's not as prevalent in the crust.
• 32:57
  Speaker 1: So you're saying that there are metal asteroids out there,
• 32:59
  Speaker 1: but there are sort of a mix of metals.
• 33:01
  Speaker 2: Yeah, exactly. It's not a pure gold asteroid, very unlikely,
• 33:05
  Speaker 2: or pure platinum. Most of these things are rocks with
• 33:08
  Speaker 2: a lot of metals mixed in and so, yes, they
• 33:10
  Speaker 2: are rich in gold and platinum. It's definitely out there.
• 33:13
  Speaker 2: But a pure gold asteroid or a silver asteroid, especially
• 33:16
  Speaker 2: when the size of the moon seems very unlikely.
• 33:19
  Speaker 1: What about gold plated, I mean it is, you know,
• 33:21
  Speaker 1: sometimes that's just as violable.
• 33:27
  Speaker 2: Well, you know, maybe we've been fooled and they actually
• 33:29
  Speaker 2: aren't filled with gold.
• 33:31
  Speaker 1: They just covered it's a pure gold inside. It's just
• 33:34
  Speaker 1: a mix of metals on the outside.
• 33:36
  Speaker 2: Well, you might wonder, like, how do we know the
• 33:38
  Speaker 2: composition of these things. It's mostly by looking at their
• 33:41
  Speaker 2: gravitational behavior. We can deduce their mass, and by looking
• 33:44
  Speaker 2: at their size, we deduce their volume, and that gives
• 33:46
  Speaker 2: us a sense of their density, and so we estimate
• 33:49
  Speaker 2: from the density of these things what they might be
• 33:51
  Speaker 2: made out of. For example, NASA is planning a mission
• 33:54
  Speaker 2: to an asteroid called Psyche, which is a big M
• 33:57
  Speaker 2: type asteroid. It's like two hundred kilometers across, and it's
• 34:01
  Speaker 2: so heavy, so dense that it has one percent of
• 34:04
  Speaker 2: the mass of the entire asteroid belt in this one
• 34:07
  Speaker 2: very metallic, very dense asteroid.
• 34:10
  Speaker 1: WHOA. Well, I wonder if maybe Mike was also asking
• 34:14
  Speaker 1: the question, like could you make a giant moon out
• 34:17
  Speaker 1: of gold? Like would it hold?
• 34:24
  Speaker 2: I don't think Mike was asking that. I think you're
• 34:26
  Speaker 2: asking that. I'm wondering what sort of like astro geoengineering
• 34:29
  Speaker 2: projects you have in mind over there.
• 34:31
  Speaker 1: Well, he's asking how large an object there or such
• 34:34
  Speaker 1: an object could there be?
• 34:35
  Speaker 2: Hmm, Yeah, that's a good question. In principle, you can
• 34:38
  Speaker 2: make an object about the size of the Earth, any
• 34:41
  Speaker 2: rocky object, anything primarily made out of heavier elements. You
• 34:45
  Speaker 2: can't really make it much bigger than the Earth because
• 34:47
  Speaker 2: then it's gravity just makes it denser and denser. You
• 34:50
  Speaker 2: can make about an earth sized blob of gold and
• 34:53
  Speaker 2: have it floating out there in the solar system.
• 34:55
  Speaker 1: Whoa, it's a lot of bling for the solar system.
• 35:01
  Speaker 2: That'd be a pretty cool engineering project. Like if you
• 35:03
  Speaker 2: come to an alien solar system and you find that
• 35:05
  Speaker 2: it's filled with like huge diamonds and Earth sized blobs
• 35:09
  Speaker 2: of gold. You might think like, Wow, these aliens know
• 35:11
  Speaker 2: what they're doing.
• 35:12
  Speaker 1: Or maybe gold is so cheap that they can make
• 35:16
  Speaker 1: a whole planet out of them.
• 35:18
  Speaker 2: Or maybe they've transcended the Kardashev scale and into the
• 35:21
  Speaker 2: Kardashian scale as you joked about it.
• 35:24
  Speaker 1: Yeah, there you go. All right, Well, thanks Mike for
• 35:28
  Speaker 1: that question. I guess the answer is that it's not likely,
• 35:32
  Speaker 1: but still possible. In the end, we don't really know.
• 35:36
  Speaker 2: In the end, almost anything is possible, but it seems
• 35:38
  Speaker 2: very unlikely for the universe to arrange for a gold
• 35:42
  Speaker 2: moon in our sky.
• 35:43
  Speaker 1: Unless Mike is secretly a super trillionaire or something.
• 35:47
  Speaker 2: If he finds that gold moon, he'll definitely be one.
• 35:49
  Speaker 1: Yeah. Other then you have to wonder why he lives
• 35:51
  Speaker 1: in New Jersey.
• 35:52
  Speaker 2: Oh he said, Brooklyn.
• 35:54
  Speaker 1: Oh, Brooklyn, Brooklyn. Oh, well that makes more sense. All right. Well,
• 35:57
  Speaker 1: let's get to our last question of the day, and
• 35:59
  Speaker 1: this one is the effects of gravitational waves on time.
• 36:04
  Speaker 1: So let's get to that. But first let's take another
• 36:06
  Speaker 1: quick break where we're asking listener questions here today, and
• 36:22
  Speaker 1: our third question comes from Max.
• 36:25
  Speaker 3: Hi, Daniel Dan JORGEV. This is Max calling from Stockholm, Sweden.
• 36:31
  Speaker 3: I have a question about gravitational waves, as they affect
• 36:37
  Speaker 3: the space, which has been proven in Bligo and Virgo,
• 36:43
  Speaker 3: do they also affect time the same way? Being compressed
• 36:49
  Speaker 3: and stressed as space, time is basically just one unit?
• 36:58
  Speaker 1: All right? Pretty cool? Can you get wavy with time?
• 37:02
  Speaker 1: Is basically the question.
• 37:04
  Speaker 2: Yeah. I love this kind of question because here again
• 37:07
  Speaker 2: he's bringing together two ideas we talk about all the time,
• 37:10
  Speaker 2: space and time are related. Gravitational waves or ripples in
• 37:13
  Speaker 2: space and time? Do they also affect time? Great question, Max.
• 37:18
  Speaker 1: Right, because I guess we know from relativity that gravity
• 37:23
  Speaker 1: is not just about making things come together. It's about
• 37:26
  Speaker 1: distorting space, and it's not just about distorting space but
• 37:29
  Speaker 1: also distorting time. Right, Like a black hole not just
• 37:32
  Speaker 1: bends space around it, but it also bends time around it.
• 37:35
  Speaker 2: Right. Yeah, that's exactly right. And there's a really important
• 37:37
  Speaker 2: progression of subtle ideas here as we go from like
• 37:41
  Speaker 2: Newton's idea of space and time to Einstein's special relativity
• 37:45
  Speaker 2: view of space and time where he brings space and
• 37:47
  Speaker 2: time together to one coherent object where they affect each other.
• 37:51
  Speaker 2: But we still have a clear sense of what time
• 37:54
  Speaker 2: is and what space is, and then into general relativity,
• 37:57
  Speaker 2: where concepts of space and time are much harder to
• 37:59
  Speaker 2: enter crprit out of our sort of generalized coordinates that
• 38:02
  Speaker 2: people use.
• 38:03
  Speaker 1: So maybe Tarrika for our listeners. What is a gravitational wave?
• 38:07
  Speaker 2: So gravitational wave is a wave in space time itself.
• 38:11
  Speaker 2: General relativity says we don't know what space time is,
• 38:15
  Speaker 2: but effectively, all we can do is measure the distances
• 38:18
  Speaker 2: between two points, Like we have this point here and
• 38:20
  Speaker 2: that point there. We can measure the distance between them,
• 38:23
  Speaker 2: and we can also measure the curvature of space, which
• 38:26
  Speaker 2: is how those relative distances change. So in space is curved,
• 38:29
  Speaker 2: things get closer together or further apart, depending on exactly
• 38:32
  Speaker 2: the nature of the curvature, and so ripples in that
• 38:35
  Speaker 2: curvature are gravitational waves because everything with energy creates curvature
• 38:41
  Speaker 2: in the universe. According to general relativity, if I have
• 38:43
  Speaker 2: a big massive object, then it's curving space and that's
• 38:46
  Speaker 2: what controls how things move around it. If I then
• 38:49
  Speaker 2: wiggle that object, then how I'm curving space is changing
• 38:53
  Speaker 2: with time because that information takes time to propagate out
• 38:56
  Speaker 2: from the wiggling object. So take a big black hole.
• 38:59
  Speaker 2: It's bending space. Now wiggle it, and you're making gravitational
• 39:03
  Speaker 2: waves from that black hole, waves in that curvature of space.
• 39:07
  Speaker 1: Right. It's kind of like about the propagation or how
• 39:11
  Speaker 1: it spreads the effects and how the group's effects of
• 39:13
  Speaker 1: gravity spread out basically.
• 39:15
  Speaker 2: Right, Yeah, if you wiggle a black hole, if the
• 39:18
  Speaker 2: curvature at a distant point doesn't instantly wiggle, right because
• 39:21
  Speaker 2: it doesn't know that you wiggle that, it takes time
• 39:23
  Speaker 2: for that information to propagate. And that's what the gravitational
• 39:27
  Speaker 2: wave is, is the propagation of that information.
• 39:29
  Speaker 4: Right.
• 39:30
  Speaker 1: Like, for example, if the Sun for some reason started
• 39:33
  Speaker 1: moving back and forth or wiggling or rocking back and forth, like,
• 39:36
  Speaker 1: we would feel that gravitational effect here on Earth, right,
• 39:39
  Speaker 1: we would feel that wiggling of the Sun gravitationally, like
• 39:43
  Speaker 1: the Earth would start to wobble too. But since it
• 39:46
  Speaker 1: takes some time for that gravitational effect to come from
• 39:48
  Speaker 1: the Sun to the Earth, that's kind of what we
• 39:50
  Speaker 1: call the wave, right, Like those wiggles as they propagate
• 39:54
  Speaker 1: out into the universe and then reach us, those are
• 39:56
  Speaker 1: the waves exactly.
• 39:58
  Speaker 2: It's very similar to other kinds of waves. You take
• 40:00
  Speaker 2: an electron has an electric field. Now you wiggle that electron,
• 40:04
  Speaker 2: you're making wiggles in that electric field. Those wiggles are photons.
• 40:08
  Speaker 2: Those ripples are updating you about where the electron is now.
• 40:12
  Speaker 2: So the same way you can create ripples in the
• 40:13
  Speaker 2: electromagnetic field by wiggling an electron, you can create ripples
• 40:17
  Speaker 2: in space time by wiggling anything that has mass.
• 40:20
  Speaker 1: All right, Now we've been able to measure those from
• 40:23
  Speaker 1: really incredible events that are happening out there in space.
• 40:26
  Speaker 2: Yeah, it's really sort of amazing. Einstein predicted these things,
• 40:30
  Speaker 2: but he also said we may never see them because
• 40:32
  Speaker 2: these are very very small. We're talking about tiny changes
• 40:36
  Speaker 2: in the distances between objects. Like you hold two mirrors
• 40:40
  Speaker 2: a couple of miles apart. The distance between them might
• 40:43
  Speaker 2: change by less than the width of a proton as
• 40:46
  Speaker 2: the gravitational wave passes by. So these things are very
• 40:49
  Speaker 2: difficult to measure. But we actually have been able to.
• 40:52
  Speaker 2: They have these very sensitive interferometers. We shoot laser beams
• 40:56
  Speaker 2: between these mirrors that are very carefully isolated from everything.
• 41:00
  Speaker 2: Credible triumph of experimental physics. And they've seen them a
• 41:02
  Speaker 2: few years ago, and now we've seen dozens and dozens
• 41:05
  Speaker 2: of these things.
• 41:06
  Speaker 1: Right, Well, as we've mentioned before, like everything moving, any
• 41:09
  Speaker 1: mass moving makes a gravitation wave. If I wave my arm,
• 41:12
  Speaker 1: I'm creating gravitational waves. They're just so small that nobody
• 41:15
  Speaker 1: can ever really feel them, although I have been working
• 41:18
  Speaker 1: out on my arm is pretty pretty massive lately.
• 41:23
  Speaker 2: Technically requires acceleration, not just motion. But yes, any accelerating
• 41:27
  Speaker 2: mass will create gravitational.
• 41:29
  Speaker 1: Waves, right right, Like if I wave my arm, right.
• 41:31
  Speaker 2: Yeah, if you move it back and forth, that's acceleration,
• 41:34
  Speaker 2: and that will create gravitational waves. Those are so tiny
• 41:36
  Speaker 2: we'll never see them. Gravitational waves we have been able
• 41:39
  Speaker 2: to see are from super incredibly massive objects black holes
• 41:43
  Speaker 2: or neutron stars swirling around each other as they collide.
• 41:47
  Speaker 1: Now, does it have to be acceleration, Like if let's
• 41:49
  Speaker 1: say an asteroid is moving in a straight line through space,
• 41:53
  Speaker 1: doesn't it create a ripple as it goes along too?
• 41:56
  Speaker 1: Because I like, I'm going to feel differently it's gravitation
• 42:00
  Speaker 1: attraction as it goes past me.
• 42:02
  Speaker 2: Well, velocity is relative, right, and so the gravitational field
• 42:06
  Speaker 2: there doesn't depend on relative quantities. It only depends on
• 42:09
  Speaker 2: absolute quantities. Acceleration is absolute, and so you don't create
• 42:14
  Speaker 2: gravitational waves. Just by having a velocity. You can experience
• 42:19
  Speaker 2: a changing gravitational field, but that's not necessarily a gravitational wave.
• 42:23
  Speaker 2: Like if you're near the Earth and you're moving away
• 42:25
  Speaker 2: from the Earth, you're measuring a change in your local
• 42:27
  Speaker 2: gravity because you're moving away from the Earth. So time
• 42:30
  Speaker 2: dependence in your position and in your velocity. But there's
• 42:34
  Speaker 2: no gravitational wave created unless you have acceleration, which is
• 42:37
  Speaker 2: an absolute quantity.
• 42:38
  Speaker 1: It's sort of a wave, right, Like if an asteroid
• 42:40
  Speaker 1: flies past me, I'm going to feel no gravity from it,
• 42:43
  Speaker 1: and then I'm going to feel a lot of gravity
• 42:44
  Speaker 1: as it's near me, and then I'm going to feel
• 42:46
  Speaker 1: les gravity as it flies away from me. Then I
• 42:48
  Speaker 1: sort of experience kind of a wave of gravity.
• 42:51
  Speaker 2: Well, again, you experience a change in how much local
• 42:54
  Speaker 2: gravity you measure, Like if you get closer to an electron,
• 42:57
  Speaker 2: you're going to measure a stronger electric field, and if
• 42:59
  Speaker 2: you move away, you're gonna measure a weaker electric field.
• 43:01
  Speaker 2: But there's no electromagnetic wave there. It's just your motion
• 43:04
  Speaker 2: relative to the electron that's changing your local measurement.
• 43:08
  Speaker 1: The effect is the same, though, don't I feel changing
• 43:12
  Speaker 1: my gravitational field over time?
• 43:15
  Speaker 2: If you wanted to create exactly the same set of
• 43:17
  Speaker 2: local measurements, you wanted an oscillating gravitational field that you
• 43:20
  Speaker 2: need to move back and forth, and that's acceleration. So
• 43:24
  Speaker 2: you can't do it without acceleration.
• 43:25
  Speaker 1: M Well, let's get to the question here. Now, we
• 43:30
  Speaker 1: know that a gravitational wave affects space. That's how we
• 43:34
  Speaker 1: measure them, right, Like we have giant rulers made out
• 43:36
  Speaker 1: of lasers very deep underground, and as they contract and
• 43:40
  Speaker 1: expand we know that a gravitational wave has passed by us.
• 43:44
  Speaker 2: Yeah.
• 43:45
  Speaker 1: Now the question is does it also affect time?
• 43:47
  Speaker 2: Yeah? And the answer is pretty unsatisfying. The answer is
• 43:52
  Speaker 2: you can't really say yes or no because it depends
• 43:55
  Speaker 2: on what time means in general relativity, which is very
• 43:58
  Speaker 2: fuzzy and unclear. That's the short version of the unsatisfying answer.
• 44:03
  Speaker 2: The longer version of the unsatisfying answer. It takes a
• 44:06
  Speaker 2: bit of a tour through special relativity. Right, Like Newton says,
• 44:10
  Speaker 2: space and time are totally separate things. Things move through
• 44:13
  Speaker 2: space there obviously, time moves forward. Space and time are unrelated,
• 44:18
  Speaker 2: Einstein tells us in special relativity, No, no, space and
• 44:21
  Speaker 2: time are two parts of the same thing. It's a
• 44:23
  Speaker 2: beautiful realization that together they make a lot more sense
• 44:27
  Speaker 2: than a part. It's like electricity and magnetism fused together
• 44:30
  Speaker 2: into one idea makes much more sense than two separate ideas.
• 44:34
  Speaker 2: This is not to say that they're the same thing.
• 44:36
  Speaker 2: Two things can be two parts of the same thing
• 44:38
  Speaker 2: without being equivalent. Like you say the front and the
• 44:41
  Speaker 2: back of the elephant are two parts of an elephant.
• 44:43
  Speaker 2: Doesn't mean the front and back are the same thing.
• 44:45
  Speaker 2: So space and time are closely related in special relativity,
• 44:49
  Speaker 2: and space affects time and time effects space. But you
• 44:51
  Speaker 2: can always still say what is time and what is space?
• 44:55
  Speaker 2: Now we get to general relativity. In general relativity, the
• 44:58
  Speaker 2: coordinates you choose, like which direction things we're moving in,
• 45:02
  Speaker 2: are not so physical. They're just sort of like abstract,
• 45:05
  Speaker 2: and you can choose lots of different sort of systems
• 45:08
  Speaker 2: in order to do your calculations, like are using polar
• 45:11
  Speaker 2: coordinates or using xyz or lots of much more complicated
• 45:15
  Speaker 2: abstract coordinate systems, And some of those coordinates it's impossible
• 45:20
  Speaker 2: to say, like which direction is time and which direction
• 45:22
  Speaker 2: is space, they're all sort of mixed together. For example,
• 45:25
  Speaker 2: as you were saying earlier, what happens as you're going
• 45:28
  Speaker 2: inside a black hole, Well, time and space sort of reverse.
• 45:31
  Speaker 2: Right now, your future is the singularity. Every path into
• 45:35
  Speaker 2: your future ends at the singularity. Time and space have
• 45:38
  Speaker 2: sort of reversed roles there. That's just sort of shorthand
• 45:41
  Speaker 2: way of saying that we have a new interpretation for
• 45:44
  Speaker 2: the coordinates.
• 45:45
  Speaker 1: Now I imagine this is super complicated, but I feel
• 45:48
  Speaker 1: like we're getting a little bit abstract here. Like I
• 45:50
  Speaker 1: wonder if Max is asking, you know, how in these
• 45:54
  Speaker 1: experiments where we can measure gravitation of ways, you can
• 45:56
  Speaker 1: see that the length of something changes as the wave
• 46:01
  Speaker 1: goes past. Does I wonder if he's asking, you know,
• 46:03
  Speaker 1: if I had a clog, would I see my clock
• 46:06
  Speaker 1: suddenly take a little faster and then take a little
• 46:08
  Speaker 1: slower as the wave goes past me.
• 46:10
  Speaker 2: The answer is, you can't really separate it out into
• 46:12
  Speaker 2: the effects of space and the effects of time, and
• 46:14
  Speaker 2: the details of it dependent a little bit on exactly
• 46:17
  Speaker 2: how you've built your clock. Like let's say, instead of
• 46:20
  Speaker 2: having lego or you have lasers, and you're shooting lasers
• 46:23
  Speaker 2: back and forth to measure distance. You have like two
• 46:25
  Speaker 2: people far apart from each other, and they're constantly sending
• 46:28
  Speaker 2: each other little laser pings. Right like, I'm going to
• 46:31
  Speaker 2: send you a pulse of lasers every one nanosecond or something,
• 46:35
  Speaker 2: and then you're going to observe those We're going to
• 46:37
  Speaker 2: try to see if the time between the pulses changes
• 46:39
  Speaker 2: as the gravitational wave goes by. Right, Well, what's going
• 46:42
  Speaker 2: to happen as the gravitational wave goes by is that
• 46:45
  Speaker 2: those pings are going to get either red shifted or
• 46:47
  Speaker 2: blue shifted by the gravitational wave. But whether you interpret
• 46:51
  Speaker 2: that as like space expanding or time slowing down depends
• 46:55
  Speaker 2: in general relativity, on these coordinate systems that you've chosen.
• 46:59
  Speaker 2: So somebody could come along and say, look, I interpret
• 47:02
  Speaker 2: this as space bending. Somebody else come along and say, no,
• 47:04
  Speaker 2: I interpret that as time bending. In general relativity, most
• 47:07
  Speaker 2: people tend to work in what's called a synchronous gauge,
• 47:11
  Speaker 2: where you basically put all the bending into the space
• 47:13
  Speaker 2: part and you say time doesn't bend at all, And
• 47:16
  Speaker 2: that's just sort of like our interpretation. But it's totally
• 47:19
  Speaker 2: valid to say no, actually, time is doing the bending.
• 47:22
  Speaker 2: So the answer is sort of like, yeah, space time
• 47:24
  Speaker 2: as a whole is bending. Whether you call that space
• 47:27
  Speaker 2: bending or time bending is a little bit arbitrary.
• 47:30
  Speaker 1: I wonder if what do you mean is like, let's
• 47:32
  Speaker 1: say a measuring time using a Grandfather clock, right with
• 47:36
  Speaker 1: like a swinging pendulum, and that's how measuring time. Now,
• 47:41
  Speaker 1: if the wave is coming let's say from directly at me,
• 47:47
  Speaker 1: and I face the Grandfather clock in one direction, then
• 47:52
  Speaker 1: maybe it's not going to fec how it takes. But
• 47:54
  Speaker 1: if I turn in ninety degrees, maybe it is going
• 47:56
  Speaker 1: to efac how it takes. And in which case you
• 47:59
  Speaker 1: might say in one instance that it did slow down time,
• 48:03
  Speaker 1: But in the other instance you might say, no, it
• 48:04
  Speaker 1: doesn't slow that time. It just stretched space.
• 48:08
  Speaker 2: Yeah, that's right. And even in the case where it
• 48:10
  Speaker 2: did slow down time, you could argue it did it
• 48:13
  Speaker 2: slow down time because time actually went slower or because
• 48:16
  Speaker 2: increase the distance that the pendulum had to swing, Right,
• 48:18
  Speaker 2: You can interpret it both ways. Sort of how even
• 48:21
  Speaker 2: in special relativity you can interpret like contraction of distances
• 48:25
  Speaker 2: and stretching of time to be two sides of the
• 48:28
  Speaker 2: same coin, Like when I travel to a nearby star
• 48:31
  Speaker 2: at nearer the speed of light, I see the distance
• 48:34
  Speaker 2: to the star contracted, so it only takes me a
• 48:36
  Speaker 2: minute to get there. Somebody else sees me flying for
• 48:39
  Speaker 2: light years, but my time is slowed down, which is
• 48:41
  Speaker 2: why it only seems like a minute for me. So
• 48:43
  Speaker 2: I see length contracted, somebody else sees time dilated. In
• 48:47
  Speaker 2: many cases, it just depends on your perspective whether you're
• 48:50
  Speaker 2: calling it a space effect or a time effect.
• 48:53
  Speaker 1: Well as it is super complicated. But I feel like
• 48:57
  Speaker 1: maybe in the past we've talked about or you've mentioned
• 49:00
  Speaker 1: there are separate effects in terms of the bending of
• 49:02
  Speaker 1: space and the slowing down of time, Like if you
• 49:05
  Speaker 1: swing by a black hole, then time will move slower
• 49:09
  Speaker 1: for you. Right, that's not up for interpretation, is it.
• 49:12
  Speaker 2: You're exactly right that there are two separate effects we're
• 49:14
  Speaker 2: talking about here. One is like velocity dependent time dilation
• 49:18
  Speaker 2: or length contraction, which is a different effect than gravitational
• 49:22
  Speaker 2: based time dilation, which is just due to the curvature
• 49:25
  Speaker 2: of space. You're totally right, those are two separate effects,
• 49:28
  Speaker 2: and you're right that the gravitational one is an absolute effect.
• 49:32
  Speaker 2: It's not like I see your time slowed down and
• 49:34
  Speaker 2: you see my time slowed down and the gravitational one.
• 49:36
  Speaker 2: Everybody agrees, like the person close to the black hole
• 49:39
  Speaker 2: agrees that their time is going slower than the person
• 49:42
  Speaker 2: further from the black hole.
• 49:43
  Speaker 1: So then what's happening as a gravitational wave goes past me?
• 49:46
  Speaker 1: Is it more like a black hole, like we're getting
• 49:48
  Speaker 1: far from a black hole, or is it more like
• 49:51
  Speaker 1: we're speeding up and slowing that.
• 49:53
  Speaker 2: The gravitational wave is a curvature effects, so it's definitely
• 49:55
  Speaker 2: more like being close to a black hole. But I
• 49:58
  Speaker 2: was going to say that even the story with being
• 50:00
  Speaker 2: close to a black hole, we're interpreting that as an
• 50:02
  Speaker 2: effect on time. You can also change your gauge. They
• 50:05
  Speaker 2: call it in general relativity, redefine the axes and pretend
• 50:09
  Speaker 2: that it's only happening in space coordinates. So in general
• 50:12
  Speaker 2: relativity you can basically interpret these things as space or time,
• 50:16
  Speaker 2: because the distinction between the two becomes much more fuzzy.
• 50:19
  Speaker 1: Even the case of going near a black hole. I me,
• 50:21
  Speaker 1: you just say that everyone can agree that time slow.
• 50:24
  Speaker 2: Down, everyone agrees about the magnitude of the effect, and
• 50:27
  Speaker 2: if both of you agree on the co ordinates, then
• 50:29
  Speaker 2: we interpret that in terms of time. So, yeah, everybody
• 50:32
  Speaker 2: agrees that the person close to the black hole has
• 50:34
  Speaker 2: a stronger effect. If you're using a certain gauge, then
• 50:37
  Speaker 2: we interpret that as a time effect. If we choose
• 50:40
  Speaker 2: a different gauge, then we interpret that as a space effect.
• 50:43
  Speaker 2: The thing we agree on is the magnitude of the effect.
• 50:46
  Speaker 2: Whether it's space or time is up to interpretation.
• 50:49
  Speaker 1: Wait, so then you already saying that when I go
• 50:51
  Speaker 1: near a black hole, I could interpret that not as
• 50:54
  Speaker 1: a change in time.
• 50:55
  Speaker 2: Yes, you could choose some weird coordinates in general relativity
• 50:58
  Speaker 2: to interpret that as just a bend of space, because
• 51:00
  Speaker 2: it is a bending of space, right, that's curvature, And
• 51:03
  Speaker 2: so if you redefine your time, then you could choose
• 51:05
  Speaker 2: time to be invariant.
• 51:07
  Speaker 1: Yeah, but it isn't the case. I mean, I know
• 51:09
  Speaker 1: this because I saw the movie Interstellar that if you
• 51:11
  Speaker 1: go near a black hole and then come back, you'll
• 51:14
  Speaker 1: be younger than me. That's not That doesn't seem like
• 51:17
  Speaker 1: it depends on a coordinate system. That's like, I'm gonna
• 51:20
  Speaker 1: see you're you're gonna be younger than me. There's no
• 51:22
  Speaker 1: way that I cannot see that.
• 51:24
  Speaker 2: If one of us takes a trip to the black
• 51:25
  Speaker 2: hole and comes back, then you completed a loop. You're
• 51:29
  Speaker 2: back to the same location in space, and that makes
• 51:32
  Speaker 2: those calculations invariant. It actually doesn't depend in that case
• 51:36
  Speaker 2: on the choice of coordinates or gauges. So yeah, in
• 51:38
  Speaker 2: that case, like in Interstellar, everyone also agrees.
• 51:42
  Speaker 1: All right, well, then let's mee just close it out then,
• 51:46
  Speaker 1: and what would say is the answer then? For Max's question,
• 51:49
  Speaker 1: does time get dilated as a gravitation away comes through
• 51:53
  Speaker 1: or can you just ignore it?
• 51:55
  Speaker 2: I would say that space time does get dilated absolutely,
• 51:58
  Speaker 2: which part of space time? Saying gets stretched out is
• 52:01
  Speaker 2: a little bit arbitrary. Most people tend to work in
• 52:04
  Speaker 2: a choice of gauges where only space is getting stretched.
• 52:08
  Speaker 2: It's just sort of simpler, and it's more natural for
• 52:10
  Speaker 2: people to choose. But in the end it is a
• 52:12
  Speaker 2: little arbitrary because it really is all of space time
• 52:15
  Speaker 2: getting squeezed.
• 52:16
  Speaker 1: All right, And if Matthew McConaughey were to serve a
• 52:18
  Speaker 1: gravitational wave, would he look come back younger or older?
• 52:23
  Speaker 1: Let he makes it too sure.
• 52:25
  Speaker 2: I think he's frozen in time. He doesn't look like
• 52:27
  Speaker 2: he's aging at all.
• 52:28
  Speaker 1: Right, right, that's what I mean that maybe that's a
• 52:30
  Speaker 1: secret he's serving gravitational waves up there.
• 52:33
  Speaker 2: Yeah, we should all be in the Matthew McConaughey gauge.
• 52:35
  Speaker 1: There you go, and then maybe we can all retire.
• 52:40
  Speaker 1: All right. Well, we tried, Max, Sorry, but it sounds
• 52:43
  Speaker 1: like the answer is that it's really complicated and you
• 52:46
  Speaker 1: need a degree in gravitational relativity to figure it out.
• 52:51
  Speaker 2: But you're right that space and time are deeply, deeply connected.
• 52:54
  Speaker 1: All right. Well, thanks to everyone who sent them their
• 52:57
  Speaker 1: questions here today. It's always fun to take a deep
• 53:00
  Speaker 1: dive into people's curiosity and to think about these scenarios
• 53:04
  Speaker 1: that we don't think about it every day.
• 53:07
  Speaker 2: Absolutely, we love your curiosity, not just because it tells
• 53:10
  Speaker 2: us that our passion for wanting to understand the universe
• 53:13
  Speaker 2: is shared by so many other people, but because it
• 53:16
  Speaker 2: actually literally powers us. Your support for science and your
• 53:19
  Speaker 2: curiosity is what makes science possible. Thank you very much.
• 53:23
  Speaker 1: Yeah, and if anyone ever makes a gold asteroid out there, hey,
• 53:27
  Speaker 1: how about you sent me a chunk of it, because
• 53:29
  Speaker 1: you know more about forty two years late on retiring.
• 53:32
  Speaker 2: Yeah, so please donate a chunk of your next gold
• 53:35
  Speaker 2: asteroid to Jorge's retirement.
• 53:37
  Speaker 1: Yeah, there you go. All right, Well, we hope you
• 53:39
  Speaker 1: enjoyed that. Thanks for joining us, See you next time.
• 53:47
  Speaker 2: For more science and curiosity, come find us on social media,
• 53:51
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• 53:59
  Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.
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