Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions #11

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Listener Questions #11 · Daniel and Kelly’s Extraordinary Universe

0:06
Speaker 1: Black holes make a gravitational wave. White chocolate is Daniel's save.
0:11
Speaker 2: What controls colors on our furry friends? It's biology, so.
0:16
Speaker 1: It depends particle colliders make mini booms. The big Bang
0:20
Speaker 1: filled the whole room.
0:22
Speaker 2: Biology, physics, archaeology, and forestry. Thank you for not asking
0:26
Speaker 2: about chemistry.
0:28
Speaker 1: What diseases you get from your cats? We'll find answers
0:31
Speaker 1: to all of that.
0:32
Speaker 2: Whatever questions keep you up at night, Daniel and Kelly's
0:35
Speaker 2: answers will make it all right.
0:37
Speaker 1: Welcome to another Listener Questions episode on Daniel and Kelly's
0:41
Speaker 1: Extraordinary Universe. Hello, I'm Kelly Wadersmith. I study parasites and space,
1:00
Speaker 1: and I'm excited to learn more about black holes today.
1:02
Speaker 2: Hi. I'm Daniel. I'm a particle physicist and I love cats,
1:06
Speaker 2: though I don't have nearly as many pets as exist
1:09
Speaker 2: on the Wienersmith Farm.
1:10
Speaker 1: Well, I mean that's hard to beat. So you're a
1:12
Speaker 1: cat person rather than a dog person, Is that what
1:14
Speaker 1: I'm hearing?
1:15
Speaker 2: Well, I grew up with cats, always loved cats, but
1:18
Speaker 2: my daughter is allergic cats. So now we have a
1:20
Speaker 2: dog and love my dog of course, and so kind
1:23
Speaker 2: of a dog person now but my daughter is getting
1:26
Speaker 2: shots so that she can tolerate cats, and we're hoping
1:28
Speaker 2: to get a cat soon.
1:30
Speaker 1: Oh exciting. Now are you going to adopt that cat?
1:32
Speaker 1: Where are you going to get the cat from?
1:34
Speaker 2: It? Was that? Or create the cat in collisions at
1:36
Speaker 2: the large hadron collider? So probably going to adopt it.
1:38
Speaker 1: Yeah, excellent. Well, we have a growing number of cats
1:42
Speaker 1: because we live on a farm in the woods and
1:44
Speaker 1: they find us and then they move in and I
1:47
Speaker 1: can never kick them out. We almost ended up with
1:50
Speaker 1: three beagles because they were also like dropped on the
1:54
Speaker 1: property and well saying no more animals. I am like
1:58
Speaker 1: simultaneously dumping pile of food in front of them. I
2:01
Speaker 1: can't help myself.
2:02
Speaker 2: Oh I see that was the other option. The option
2:04
Speaker 2: is adopt cats or have them adopt you, which is
2:06
Speaker 2: what you're doing on the farm.
2:08
Speaker 1: Yep, yep, although the goats I think I will be
2:11
Speaker 1: purchasing directly.
2:13
Speaker 2: Well, there's some sort of gravitational cat hole effect there,
2:16
Speaker 2: I think, because the more cats you get, the more
2:18
Speaker 2: they attract more cats, and then cats hear about your
2:20
Speaker 2: farm they're like, oh wow, it's a cat haven, and
2:23
Speaker 2: pretty soon you're gonna be a cat lady.
2:24
Speaker 1: Yeah, it's true. And we're also getting into chicken math.
2:27
Speaker 1: Have you heard about chicken math?
2:29
Speaker 2: Tell me about chicken math.
2:31
Speaker 1: It's when you decide you're going to get four chickens
2:33
Speaker 1: because it's not really that much work. So you actually
2:35
Speaker 1: get ten chickens, and then before you know what, the
2:38
Speaker 1: order you put in actually had a four in the front,
2:40
Speaker 1: and now you've got forty chickens. And anyway, I did
2:43
Speaker 1: duck math recently, and so now we have five ducks
2:46
Speaker 1: and two geese coming. My husband's not excited about the geese.
2:51
Speaker 1: We decided we were gonna name the geese Jacques Gusta
2:55
Speaker 1: and franc Scene Gusto. I think Jacques had two wives.
2:58
Speaker 1: One of them was Franccene. Anyway, we're very excited.
3:01
Speaker 2: Well, at least you have control over the names of
3:03
Speaker 2: the pets, even if not the species or number of them.
3:07
Speaker 2: Gives you a little bit of illusion of control.
3:09
Speaker 1: That's right. All that matters is that they let me
3:11
Speaker 1: snuggle them.
3:12
Speaker 2: And in this crazy universe that can sometimes feel out
3:14
Speaker 2: of our control, one way we can sort of establish
3:17
Speaker 2: a little bit of a finger hold on sanity is
3:20
Speaker 2: to think about the universe and try to understand it,
3:23
Speaker 2: try to grapple with the mysteries of the cosmos, and
3:26
Speaker 2: the best way to do that is to start by
3:28
Speaker 2: asking questions. Questions we have and questions that you have.
3:32
Speaker 1: Chicken math might not make sense, but Daniel and Kelly's
3:35
Speaker 1: answers do. So if you would like to submit your
3:37
Speaker 1: questions about the universe, write us at questions at danielands
3:41
Speaker 1: Kelly dot org. And it might take us a little
3:43
Speaker 1: while before your answer airs, because we are actually fairly
3:47
Speaker 1: well organized and we're about two months ahead of schedule,
3:49
Speaker 1: and we've got a bit of a list of questions.
3:51
Speaker 1: But you will get an answer from us, for sure.
3:53
Speaker 1: We respond to everyone that's.
3:55
Speaker 2: Right right to us with your questions at questions at
3:58
Speaker 2: Daniel and Kelly dot org. Everyone gets an answer, and
4:01
Speaker 2: some people get on the podcast. And today we have
4:03
Speaker 2: questions from three listeners about black holes, about furry pets,
4:07
Speaker 2: and about tiny little bangs. Our first question comes from
4:11
Speaker 2: Mark from Ireland about black holes. Here's Mark's question.
4:15
Speaker 3: Hi, Daniel and Kelly, this is Mark from Ireland and
4:19
Speaker 3: I have a question about merging black holes. When two
4:23
Speaker 3: black holes spiral towards each other to merge, they lose
4:27
Speaker 3: mass and in doing so, generates gravitational waves. The newly
4:32
Speaker 3: formed black hole will have a mass less than the
4:34
Speaker 3: sum of the two original black holes. My question is
4:39
Speaker 3: what actual mass is converted into gravitational waves and how
4:44
Speaker 3: does this happen? In trying to get my head around
4:47
Speaker 3: this phenomenon, I see there are lots of other interesting
4:50
Speaker 3: questions that might arise. Maybe you can explain the merging
4:54
Speaker 3: process and detail. I really enjoy the podcast and look
4:59
Speaker 3: forward to new episodes. Thank you and keep up the
5:02
Speaker 3: good work.
5:03
Speaker 1: Whoa great question. Okay, so I'm going to assume that
5:06
Speaker 1: we've never actually seen black holes collide and we are
5:09
Speaker 1: guessing what happens, or have we seen black.
5:11
Speaker 2: Holes Colyde, depends what you mean by seeing and black holes.
5:14
Speaker 2: But yes, we actually have seen black holes collide. We've
5:18
Speaker 2: observed these ingravitational waves collisions of dozens and dozens of
5:23
Speaker 2: pairs of black holes. Now it seems sort of fantastical
5:26
Speaker 2: and science fiction y, but it's our reality.
5:29
Speaker 1: Okay, So then what did you mean when you said
5:31
Speaker 1: it depends what you mean by black holes and observe,
5:34
Speaker 1: because it sounds like we have seen black holes collide.
5:38
Speaker 2: Yeah, I think most people in astronomy would say that
5:40
Speaker 2: we have seen black holes collide. Okay, but you know,
5:42
Speaker 2: we don't technically know that they are black holes. We've
5:45
Speaker 2: seen very dense, compact, dark objects which are consistent with
5:50
Speaker 2: black holes collide, that we've never really observed the event
5:53
Speaker 2: horizon directly, So there's an asterisk there on do we
5:56
Speaker 2: really know black holes are black holes? And in terms
5:59
Speaker 2: of seeing, we've observed the radiation generated by that collision,
6:03
Speaker 2: and that's what today's question is all about, how those
6:04
Speaker 2: black holes merge and the radiation they give off. So
6:07
Speaker 2: we've observed that gravitational radiation and it looks exactly like
6:11
Speaker 2: you would expect from black holes colliding. But I don't
6:13
Speaker 2: know if that counts as seeing it because it's not
6:15
Speaker 2: like visible light.
6:17
Speaker 1: Okay, all right, I got it. So let's start from
6:19
Speaker 1: the basics. What's a black hole?
6:22
Speaker 2: Right? So black hole famous prediction from classical general relativity. Right,
6:27
Speaker 2: This is Einstein's theory that space is curved. Gravity is
6:30
Speaker 2: not really a force. So what you think is gravity
6:33
Speaker 2: is actually just the effect of space time being curved.
6:36
Speaker 2: If you don't notice that space time is curved, it
6:38
Speaker 2: looks like something is bending the light or changing the
6:41
Speaker 2: path of the Earth. But it's actually just the curvature
6:44
Speaker 2: of space time. Space time curves in response to mass,
6:47
Speaker 2: and if you get enough mass in a small area,
6:50
Speaker 2: it curves space time so much that things get trapped.
6:53
Speaker 2: Space time is curved so that like light can't even escape.
6:57
Speaker 2: It's not like there's so much gravity it even pulls
6:59
Speaker 2: on photon. It's that space itself is bent so that
7:03
Speaker 2: inside a black hole, space only points towards the center.
7:06
Speaker 2: And so this creates the phenomenon we call the event horizon,
7:09
Speaker 2: beyond which anything that falls in is trapped. It will
7:13
Speaker 2: only move towards the center of the black hole. And
7:16
Speaker 2: so this is the defining feature of a black hole,
7:18
Speaker 2: the event horizon. This is the thing we haven't actually
7:21
Speaker 2: literally technically observed. We've seen lots of indirect evidence for
7:25
Speaker 2: black holes, but never actually observe the event horizon. And
7:28
Speaker 2: beyond the event horizon, we can't tell anything that happens.
7:31
Speaker 2: We can know the mass of the black hole, we
7:33
Speaker 2: can know if it has electric charge, we can know
7:34
Speaker 2: if it's spinning, but everything else is shrouded in mystery.
7:38
Speaker 1: We've done eleven of these listener questions episodes so far.
7:41
Speaker 1: In thinking back, I feel like most of them have
7:45
Speaker 1: had at least a question about a black hole. What
7:47
Speaker 1: do you think it is about black holes that keep
7:50
Speaker 1: people up at night?
7:51
Speaker 2: I think it's an incredible prediction of physics, something so
7:54
Speaker 2: strange and beyond our intuition. But macroscopic, right, like quantum
7:58
Speaker 2: mechanics makes all sorts of weirds about electrons, what they're
8:01
Speaker 2: secretly doing while you're asleep, whatever, But we'll never see
8:04
Speaker 2: those because they're microscopic. You can never observe them. Black
8:07
Speaker 2: holes are a prediction that are like technically you could
8:10
Speaker 2: see you could be near a black hole and observe
8:12
Speaker 2: it and see all this strange effects. So it feels
8:14
Speaker 2: sort of like magic, I think. And yeah, you're right,
8:17
Speaker 2: people are fascinated by black holes. It's a significant fraction
8:20
Speaker 2: of the questions that we get are about black holes.
8:23
Speaker 2: So yeah, absolutely, it's fantastic. It's wonderful. It's incredible that
8:26
Speaker 2: we've actually seen them, and we've seen these collisions. I
8:29
Speaker 2: remember in the late nineties deciding where to go to
8:32
Speaker 2: graduate school and what to work on, and I had
8:33
Speaker 2: an opportunity to work on this project Lego the gravitational
8:37
Speaker 2: wave observatory, and they were looking to see these black
8:40
Speaker 2: holes merging and the gravitational waves generated by them. And
8:42
Speaker 2: I remember thinking, they're never going to make that work.
8:45
Speaker 2: It's crazy, and so I decided not to work on that.
8:48
Speaker 2: And then of course they won the Nobel Prize. But
8:51
Speaker 2: you know, hey, maybe if I had worked on it,
8:53
Speaker 2: it wouldn't have worked out, and they wouldn't have won
8:55
Speaker 2: a Nobel Prize. So maybe they won the Nobel Prize
8:58
Speaker 2: because I didn't work on it.
9:00
Speaker 1: Anyway, hard to say, do you ever regret not going
9:03
Speaker 1: into black holes? Or are you totally happy with the
9:05
Speaker 1: path your life took?
9:07
Speaker 2: You know, there are always other options you could consider,
9:09
Speaker 2: but I'm pretty happy with how everything worked out, and
9:11
Speaker 2: so yeah, I don't worry too much about the counterfactuals.
9:14
Speaker 2: But it is amazing that humanity has figured out a
9:16
Speaker 2: way to observe these collisions. Einstein predicted this decades and
9:20
Speaker 2: decades ago, but he thought it was going to be
9:21
Speaker 2: impossible to observe because gravitational radiation is very, very weak,
9:25
Speaker 2: because gravity itself is not very powerful, and so you
9:29
Speaker 2: need an extraordinarily sensitive instrument to see this stretching and
9:33
Speaker 2: squeezing of space time, this gravitational radiation, unless, of course,
9:37
Speaker 2: you're right next to the black holes colliding, in which
9:39
Speaker 2: case the signal is very powerful and you're probably dead.
9:43
Speaker 1: I feel like that's another thing that gets people interested
9:46
Speaker 1: in the idea that observing this could kill you, but
9:49
Speaker 1: if you could survive what's on the other side, I
9:52
Speaker 1: just feel like it's amazing. But Okay, so we have
9:54
Speaker 1: observed collisions, and you said that we've observed a lot
9:57
Speaker 1: of them, and.
9:58
Speaker 2: It was a little bit of a surprise when we
10:00
Speaker 2: saw the first one. You know, we didn't know how
10:02
Speaker 2: often does this happen in the universe. We're building our
10:04
Speaker 2: first eyeball for gravitational waves, and how long it takes
10:07
Speaker 2: the sea one depends on how often they happen, and
10:09
Speaker 2: there were lots of predictions. Some people predicted that it
10:12
Speaker 2: would take decades to see one, but they saw one
10:14
Speaker 2: almost immediately after turning the thing on, and everyone's like,
10:18
Speaker 2: oh my gosh. Wow. So it turns out these collisions
10:21
Speaker 2: happen more often than people suspected.
10:23
Speaker 1: So does that mean we were totally off in our
10:26
Speaker 1: predictions for how many black holes there are or how
10:29
Speaker 1: much they're moving? Around what were we wrong about in particular.
10:32
Speaker 2: So we're not sure. Black hole formation is still kind
10:34
Speaker 2: of mystery. Super massive black holes or things we don't
10:37
Speaker 2: really understand, so something we're still trying to understand and
10:40
Speaker 2: we don't understand. Also the distribution of black hole masses.
10:43
Speaker 2: There seem to be some smaller ones, some bigger ones,
10:45
Speaker 2: but there aren't intermediate sized ones. So there's a lot
10:49
Speaker 2: we don't understand about black hole formation, how often it happens,
10:52
Speaker 2: how often they're close to each other, right, this kind
10:54
Speaker 2: of stuff, So a lot of really interesting astrophysics is
10:57
Speaker 2: being opened up by this study.
10:59
Speaker 1: No gold locks black holes, and Mark.
11:02
Speaker 2: Is interested in what happens when these two black holes
11:05
Speaker 2: form and where the mass goes, because you know, there's
11:08
Speaker 2: nothing free in the universe. If two black holes collide
11:11
Speaker 2: and produce gravitational waves, gravitational waves carry energy. They're stretching
11:15
Speaker 2: and squeezing of space time, and that energy has to
11:18
Speaker 2: come from somewhere, and it comes from the internal energy
11:21
Speaker 2: of the black hole system. These two things are orbiting
11:24
Speaker 2: each other and for them to collapse down into one,
11:26
Speaker 2: they have to lose that angular momentum, so they radiate
11:29
Speaker 2: it away in gravitational waves and Marx's questions trying to
11:32
Speaker 2: understand where the mass goes, because the mass of the
11:35
Speaker 2: resulting black hole is not just the sum of the
11:39
Speaker 2: masses of the two black holes that go in. It's
11:41
Speaker 2: smaller than that because energy is lost to gravitational waves.
11:45
Speaker 1: And we have talked in other episodes about how energy
11:48
Speaker 1: is mass, but maybe not. It's complicated, is that, right?
11:53
Speaker 2: Yeah, Mass is a measure of internal stored energy. Right,
11:57
Speaker 2: So like a proton's mass, it's not just the mass
11:59
Speaker 2: of the stuff that makes it up. It's the mass
12:01
Speaker 2: of the stuff that makes it up, plus the energy
12:03
Speaker 2: they have relative to each other. In fact, most of
12:05
Speaker 2: the mass of the proton comes from that energy, the
12:07
Speaker 2: binding energy of the quarks together. So if you have
12:11
Speaker 2: a black hole black hole system, two black holes orbiting
12:14
Speaker 2: each other, the mass of the whole system is the
12:17
Speaker 2: massive black hole one plus the massive black hole two
12:20
Speaker 2: plus their relative energy, and that's a lot. There's a
12:23
Speaker 2: lot of gravitational energy between those two black holes. Let's
12:26
Speaker 2: say black hole one is forty masses of the Sun,
12:29
Speaker 2: for example, and black hole two is thirty masses of
12:32
Speaker 2: the Sun. These are typical numbers. Then the energy of
12:34
Speaker 2: the whole system would be forty plus thirty plus whatever
12:38
Speaker 2: energy they have in their relative rotation, and that could
12:41
Speaker 2: be like thirty or forty or fifty, right, it depends
12:43
Speaker 2: on the configuration. So the total energy of the system
12:46
Speaker 2: could be much more than seventy. You could be one hundred,
12:48
Speaker 2: one hundred and twenty, this kind of thing. But a
12:51
Speaker 2: lot of that energy is lost when the two radiated
12:54
Speaker 2: away in order to combine. They have to radiate away
12:57
Speaker 2: some energy in order to combine, otherwise they would just
13:00
Speaker 2: or bit forever.
13:01
Speaker 1: And are they losing the energy of the black holes
13:04
Speaker 1: or are they losing the energy that surrounds the black
13:06
Speaker 1: holes or a little bit of both.
13:08
Speaker 2: Yeah, So this is a great question. And this is
13:09
Speaker 2: what Mark is asking, is like he wants to do
13:11
Speaker 2: some accounting. Is their mass actually lost? And I think
13:14
Speaker 2: he's interested in this because people think of black holes
13:17
Speaker 2: as something that can never lose mass, right at least
13:19
Speaker 2: in classical general relativity, And so he's wondering, like, is
13:22
Speaker 2: this a way for mass to escape somehow the black holes?
13:26
Speaker 2: And it's a little bit tricky. There's a couple of
13:28
Speaker 2: things to keep in mind. So the final black hole
13:31
Speaker 2: is smaller than the sum of the two original black holes,
13:34
Speaker 2: but always larger than either of them. So neither black
13:38
Speaker 2: hole shrinks. Both black holes grow.
13:41
Speaker 1: Nope, no, no, no, You've lost me. Don't they become
13:44
Speaker 1: one black hole when they merge.
13:46
Speaker 2: Yes, they become one black hole exactly, And so there's
13:49
Speaker 2: no shrinking of the event horizon. Like the final event
13:52
Speaker 2: horizon is bigger than either of the incoming event horizons. Okay,
13:56
Speaker 2: so no event horizon is shrinking. It's not like you're
13:58
Speaker 2: seeing behind the event horizon of either black hole. Both
14:02
Speaker 2: of them are growing, right, but the final is smaller
14:05
Speaker 2: than the sum of the two parts. It feels trickier.
14:07
Speaker 2: It feels like I'm cheating.
14:09
Speaker 1: Yes, so I guess what I'm not following is Okay,
14:11
Speaker 1: when they merge, I no longer think of them as
14:13
Speaker 1: two separate parts. They're just one part. But it sounds
14:16
Speaker 1: like you are still trying to keep accounting on two parts,
14:20
Speaker 1: but now they've become one. So what am I missing?
14:24
Speaker 2: Yeah? I think think about it from the point of
14:26
Speaker 2: view of black hole one. Okay, black Hole one has
14:29
Speaker 2: an event horizon, and it has a certain mass, and
14:32
Speaker 2: you could just be in its reference frame and it
14:34
Speaker 2: has another black hole orbiting it, right, and then that
14:37
Speaker 2: black hole radiates some energy and falls in and it
14:40
Speaker 2: gets gobbled up. Black Hole one grows. Right, So we
14:44
Speaker 2: followed all the rules of general relativity. The event horizon
14:46
Speaker 2: is not shrunk because it can never shrink, because if
14:49
Speaker 2: it did, you'd see things inside the event horizon. It
14:52
Speaker 2: has grown. Its mass has gone up. Right, in classical
14:55
Speaker 2: general relativity, black hole masses can only go up. So
14:58
Speaker 2: from the point of view of black hole one, the
15:00
Speaker 2: fact that black hole two is a black hole is
15:02
Speaker 2: kind of irrelevant. It's eaten some energy and it's grown.
15:06
Speaker 2: You can play the same game from the point of
15:08
Speaker 2: view a black hole two. Right, The thing is symmetric.
15:10
Speaker 2: Black Hole two grows, it gains mass, it's eating black
15:14
Speaker 2: hole one. The two merge. The final result is bigger
15:17
Speaker 2: than black hole two. Everything is happy from a general
15:20
Speaker 2: relativity point of view.
15:21
Speaker 1: Okay, so at the end you still have just one
15:24
Speaker 1: black hole, but that one black hole is bigger than
15:28
Speaker 1: black hole one or black hole two were originally.
15:32
Speaker 2: Yes, exactly, Okay, and so it feels like mass has
15:35
Speaker 2: been lost and we're playing some sort of shell game here.
15:38
Speaker 2: I think there's another thing to understand that might help people,
15:41
Speaker 2: which is, the mass of the black hole doesn't just
15:44
Speaker 2: depend on what's beyond the event horizon. You can make
15:48
Speaker 2: a black hole more massive without crossing the event horizon. So,
15:51
Speaker 2: for example, say I shoot Kelly into orbit around a
15:54
Speaker 2: black hole, hypothetically speaking, or Zach. Should we talk about Zaz? Yeah, yes,
16:00
Speaker 2: of course Zach is in orbit around a black hole. Okay,
16:03
Speaker 2: Now that black hole's mass grows even before Zach goes
16:07
Speaker 2: over the event horizon. Right, you tend to think like, oh,
16:10
Speaker 2: it's has to eat Zach before it grows to add
16:12
Speaker 2: to its mass. But the mass is a measure of
16:15
Speaker 2: the energy of the system, right, So the black hole's
16:18
Speaker 2: mass actually grows before Zach falls over the event horizon.
16:23
Speaker 1: So at what point does Zach become part of the
16:25
Speaker 1: system mm.
16:26
Speaker 2: Hmm, Well when he has a relationship to it, like
16:28
Speaker 2: it's a gravitationally bound to it, than to an external
16:31
Speaker 2: observer who's like a little bit further away, like it's
16:34
Speaker 2: a black hole, Zach's system. The whole thing has more
16:37
Speaker 2: mass than the black hole or than Zach does, and
16:41
Speaker 2: so you don't have to like add stuff to the
16:44
Speaker 2: black hole over the event horizon in order for the
16:46
Speaker 2: black hole to gain in mass. This is actually crucial
16:50
Speaker 2: for the way that black holes actually grow in the universe.
16:52
Speaker 2: You might have heard, for example, if you do throw
16:54
Speaker 2: your husband into a black hole, you'll never actually see
16:57
Speaker 2: him cross the event horizon because time slows down. And
17:00
Speaker 2: a lot of people write it and say, all right,
17:02
Speaker 2: but then how do black holes actually grow if nothing
17:04
Speaker 2: can cross the event horizon because time slows down. But
17:07
Speaker 2: the answer is that the event horizon grows before Zack
17:10
Speaker 2: reaches it. It grows out to meet him. He and
17:13
Speaker 2: the event horizon approach each other. And so if Zach
17:17
Speaker 2: was the last thing you ever threw into a black hole,
17:19
Speaker 2: it's true that he would never cross it, you'd never
17:21
Speaker 2: see him. But if after you throw Zach into a
17:24
Speaker 2: black hole, you feel bad and you throw him a sandwich,
17:26
Speaker 2: and that sandwich approaches the black hole, and as it
17:29
Speaker 2: approaches the black hole, it pulls the event horizon over Zack, right,
17:33
Speaker 2: because the event horizon comes out to meet the thing
17:36
Speaker 2: that's approaching it. Because again, the mass of the black
17:39
Speaker 2: hole depends on the stored energy, which includes the gravitational
17:42
Speaker 2: energy it has with things around it. So you shouldn't
17:45
Speaker 2: think of these things as just like boxes, right, Remember,
17:47
Speaker 2: mass it's not just like a measure of how much
17:49
Speaker 2: stuff is inside the black hole. It's a more comprehensive
17:53
Speaker 2: measure of the energy of that whole system. You don't
17:56
Speaker 2: have to be over the event horizon in order to
17:58
Speaker 2: be part of that system.
18:00
Speaker 1: So one, the next time you say biology is complicated,
18:04
Speaker 1: I'm going to just start laughing right away. But okay. Two,
18:06
Speaker 1: So if you threw Zach ten thousand sandwiches because you
18:10
Speaker 1: are like you're going to be there for a while,
18:12
Speaker 1: would the event horizon pass Zach faster than if you
18:16
Speaker 1: just threw him one sandwich because you don't really care
18:19
Speaker 1: about what happens in the long run.
18:21
Speaker 2: Mm hmm, yeah, absolutely, okay. And if you threw them
18:24
Speaker 2: in a series, then chicken sandwich number one would pass first,
18:28
Speaker 2: chicken sandwich number two, then chicken number three, and the
18:31
Speaker 2: last chicken sandwich would not cross the event horizon. So
18:34
Speaker 2: it's true, you can't see something cross the event horizon
18:37
Speaker 2: if it's the last thing that you throw. But in
18:40
Speaker 2: our universe there's never a last thing. There's always like
18:42
Speaker 2: more gas and more particles. And that's how black holes
18:44
Speaker 2: in the universe actually grow, all right, But back to
18:47
Speaker 2: Mark's question, what's going on here is that the mass
18:51
Speaker 2: of the whole system. Right, Let's say we start with
18:53
Speaker 2: our example of a forty and a thirty black hole,
18:56
Speaker 2: and together they have a mass of like one hundred
18:58
Speaker 2: and twenty, right, including all gravitational energy and rotational energy.
19:02
Speaker 2: As they inspirle, they radiate away a bunch of that energy.
19:06
Speaker 2: So the mass of the system was one twenty. It's
19:08
Speaker 2: radiated away I don't know sixty. So now the final
19:11
Speaker 2: black hole is sixty instead of one twenty. So sixty
19:15
Speaker 2: is bigger than forty and bigger than thirty, but smaller
19:18
Speaker 2: than forty plus thirty. But all that's happened is that
19:21
Speaker 2: some of that rotational gravitational energy has been radiated away.
19:25
Speaker 2: So even though the whole system started out with mass
19:28
Speaker 2: of one twenty, now it's down to sixty because it's
19:30
Speaker 2: radiated away half of its energy. I'm just making up
19:33
Speaker 2: these numbers. They're roughly correct in the order of magnitude,
19:36
Speaker 2: but I haven't done like any calculations. But that's the
19:38
Speaker 2: right way to think about it as the energy of
19:40
Speaker 2: the whole system.
19:41
Speaker 1: All right, Well, I think I understand black holes better now,
19:45
Speaker 1: although I say that after every explanation and then I
19:49
Speaker 1: get things wrong the next time we talk about it.
19:51
Speaker 1: But let's see what Mark from Ireland thinks of that explanation.
19:55
Speaker 3: Hi, Daniel and Kelly, thank you very much for that
19:58
Speaker 3: very informative answer to mike question. I think black holes
20:02
Speaker 3: are really amazing, and merging black holes are even more amazing.
20:07
Speaker 3: It's incredible that during the final fifth of a second
20:09
Speaker 3: of their inward spiral, that they are flying around one
20:13
Speaker 3: another at near relativistic speeds, often up to a rate
20:17
Speaker 3: of two hundred and fifty orbits a second, and radiate
20:21
Speaker 3: the equivalent of multiple solar masses of energy in the
20:24
Speaker 3: former gravitational waves. It really is crazy, crazy physics. Well,
20:29
Speaker 3: you've answered my questions very well, and thank you both
20:33
Speaker 3: for taking the time to do so. I'm sure you'll
20:36
Speaker 3: hear from me again at some stage in the future,
20:38
Speaker 3: and in the meantime, I'm going to keep listening in.
20:57
Speaker 1: All right, So now we are onto by all, from
21:00
Speaker 1: black holes to black spots. We are talking about patterns
21:03
Speaker 1: on our furry friends. Let's hear what Simon from Germany
21:07
Speaker 1: wanted to know about.
21:09
Speaker 4: Hi, Daniel N. Kelly Simon here from Germany. Thanks for
21:12
Speaker 4: a great podcast. They're a fine background to my daily
21:16
Speaker 4: run in the woods. I have a question here for Kelly,
21:19
Speaker 4: one that has puzzled me for quite some time, and
21:22
Speaker 4: it's in relation to the coloration of our furry friends.
21:27
Speaker 4: So if we take a dog, for example, who is
21:29
Speaker 4: black and white, and we zoom into the border between
21:33
Speaker 4: the two colors, presumably we have one skin cell or
21:37
Speaker 4: hair cell with black pigmentation and the neighboring cell as
21:41
Speaker 4: a white pigmentation. The question is how is this information
21:46
Speaker 4: passed down? Presumably the information is contained in a precursor cell,
21:51
Speaker 4: one splitting into a black and one into a white.
21:54
Speaker 4: The question is what is the mechanism for this? Thanks
21:57
Speaker 4: for a great podcast, guys, Keep up the good work,
22:00
Speaker 4: and I look forward to hearing some insight into this question.
22:03
Speaker 2: See biology also has really massively important questions.
22:07
Speaker 1: Are you being facetious?
22:08
Speaker 2: I can't tell no, I'm trying to make a gravitational pun.
22:12
Speaker 1: Oh good, excellent? Okay, sorry, went right over my head.
22:15
Speaker 1: All right, So this was actually a fairly difficult question
22:19
Speaker 1: to read about and to try to understand. And it's biology.
22:22
Speaker 1: So it depends.
22:24
Speaker 2: Let me see if I can interpret the question to
22:25
Speaker 2: make sure I understand what he's asking. Okay, I think
22:28
Speaker 2: he's basically trying to do some physics here, which is
22:30
Speaker 2: to like zoom in on the microprocesses involved. He's like
22:34
Speaker 2: looking at his dog and seeing there's white patches and
22:37
Speaker 2: black patches and wondering like what makes one bit white
22:40
Speaker 2: and one black? And he's trying to understand it by
22:42
Speaker 2: zooming in on the boundary and saying like, there's got
22:44
Speaker 2: to be a point where there's one cell that's white
22:47
Speaker 2: and one cell that's black, and that's where the difference is.
22:50
Speaker 2: And he wants to highlight like what's going on between
22:53
Speaker 2: those cells to understand why one turns white and black,
22:56
Speaker 2: but also obviously to zoom out and understand, like how
22:59
Speaker 2: do you get these patterns?
23:00
Speaker 1: Yes, And that's how I interpreted the question as well.
23:03
Speaker 1: And the answer is that if you are looking at
23:06
Speaker 1: animal patterns in general, it depends on the colors, it
23:10
Speaker 1: depends on the pattern shape, it depends on the animal.
23:13
Speaker 1: But Simon in particular referenced dogs and referenced white and black,
23:18
Speaker 1: and so I decided that I was going to hone
23:21
Speaker 1: in on that in particular, all right, because I needed
23:23
Speaker 1: a foothold for this question. And so in dogs, there
23:27
Speaker 1: are hair follicles or fur follicles that produce either black
23:32
Speaker 1: or brown colors, or yellow or white colors. So one
23:36
Speaker 1: follicle can produce either of those colors depending on the
23:40
Speaker 1: instructions that it's given. So it's not like you have
23:43
Speaker 1: different kinds of cells next to each other. It's all
23:46
Speaker 1: the same cell, but it just is following different sets
23:49
Speaker 1: of instructions.
23:51
Speaker 2: So they're just like printers, and they can get an
23:52
Speaker 2: instruction for a black hair or a white hair and
23:55
Speaker 2: they're happy to do it.
23:56
Speaker 1: That's right, Yes, exactly.
23:57
Speaker 2: Interesting, So who sends the instructions?
24:00
Speaker 1: So the instructions are encoded in a gene called a gooty,
24:05
Speaker 1: and this gene is important for coloration in a lot
24:08
Speaker 1: of different species, and the gene produces a hormone. The
24:13
Speaker 1: hormone gets released from the cell.
24:15
Speaker 2: I'm a little confused because a gene is part of
24:18
Speaker 2: your DNA, and so when you're saying the gene produces
24:21
Speaker 2: a hormone, do you mean the gene when it's transcribed
24:24
Speaker 2: into a protein is that hormone or the gene when
24:27
Speaker 2: transcribed into a protein. Is some little machine that makes
24:30
Speaker 2: the hormone or excuse my naive biologic question.
24:33
Speaker 1: No, No, that's a great question. I skipped a bunch
24:34
Speaker 1: of steps. So, as I understand it, the gene encodes
24:37
Speaker 1: for a hormone, and so when that gene is essentially
24:40
Speaker 1: read and turned into a protein, that protein is a
24:44
Speaker 1: hormone that subsequently gets released from the cell.
24:47
Speaker 2: The hair follicle cell, or some other kind of cell
24:49
Speaker 2: that's controlling the hair follicle cells.
24:51
Speaker 1: What I think is happening here is that hair follicle
24:53
Speaker 1: cells are producing this message and then also sharing it
24:56
Speaker 1: with nearby cells.
24:57
Speaker 2: Oh interesting, Okay, one.
25:00
Speaker 1: Gets released and it talks to the nearby cells. If
25:03
Speaker 1: you are a hair follicle next to a cell that
25:06
Speaker 1: has just released this hormone, then you produce white.
25:11
Speaker 2: Interesting.
25:12
Speaker 1: If you don't get that hormone message, you default to
25:16
Speaker 1: making black or brown?
25:18
Speaker 2: Wow? Fascinating right.
25:19
Speaker 1: So cells can do either, and so the question is
25:24
Speaker 1: why are some cells making the signal that say turn
25:28
Speaker 1: on white and why are some cells not making that
25:31
Speaker 1: signal and telling nearby cells to default to brown or black?
25:35
Speaker 2: I loveI we like follow the chain of logic here like,
25:38
Speaker 2: this is happening because of that, because of that, because
25:40
Speaker 2: of that, because of that, and now we're like detectives
25:42
Speaker 2: following the clues all the way back to the source.
25:44
Speaker 2: So are you going to tell us who the killer is?
25:46
Speaker 2: Who is making these decisions about whether to produce this hormone?
25:49
Speaker 1: You know, it's biology, so that the answer is never,
25:51
Speaker 1: you know, kernel mustard. It's much more complicated. So you've
25:55
Speaker 1: got this a gooty gene, And what determines whether or
25:58
Speaker 1: not genes are turned on or off is that there
26:00
Speaker 1: are these regions called promoters, and when something binds to
26:03
Speaker 1: the promoter, that can turn the gene on. And so
26:06
Speaker 1: it seems that whether or not this hormone is made
26:09
Speaker 1: or not has to do with some complicated interactions happening
26:11
Speaker 1: with the promoter for the genes. And so some cells
26:14
Speaker 1: have these promoters turned on, so they're making this make
26:18
Speaker 1: white message, and some genes don't get this promoter turned on,
26:21
Speaker 1: so they are not giving a message, and nearby cells
26:24
Speaker 1: make black or brown. Part of why I didn't get
26:26
Speaker 1: into the details is because it might help you understand
26:29
Speaker 1: exactly what's happening in this very particular instance. But to
26:33
Speaker 1: understand coloration in general, that's more a story about promoters
26:37
Speaker 1: getting turned on or off.
26:38
Speaker 2: So in general, then how do promoters get turned on
26:42
Speaker 2: or off? I mean, this is part of your DNA,
26:44
Speaker 2: what determines whether or not that DNA is getting turned
26:47
Speaker 2: on or off.
26:48
Speaker 1: In general, we don't understand what's happening super well here,
26:51
Speaker 1: and we understand this process a lot better in rodents
26:54
Speaker 1: in birds, and in part that's because we feel much
26:57
Speaker 1: more comfortable doing experiments on these animals in the lab.
27:00
Speaker 2: All that's kind of sad, I know.
27:02
Speaker 1: I know it is sad, But then you can also
27:04
Speaker 1: pick animals that have much simpler color patterns and fewer
27:08
Speaker 1: colors to boots, and that makes it easier to sort
27:10
Speaker 1: of get a handle on these sorts of things, whereas
27:12
Speaker 1: dogs have loads of different color patterns, and so trying
27:16
Speaker 1: to get a handle on all of the different ways
27:18
Speaker 1: these patterns can be made is much more complicated. The
27:21
Speaker 1: manuscript that I read even had a sentence being like,
27:23
Speaker 1: the situation in dogs is still unresolved, but they're doing
27:26
Speaker 1: their best to figure it out.
27:27
Speaker 2: Well, this is super interesting how we can go from
27:29
Speaker 2: like totally clues about it to understanding, Oh, follicles can
27:33
Speaker 2: print either color to understanding what controls what they print,
27:36
Speaker 2: and then follow that up the chain, and we're still
27:38
Speaker 2: crawling up the chain. It's incredible.
27:40
Speaker 1: It is incredible, And like I said, we've got a
27:42
Speaker 1: better handle on some species. And animal coloration in general
27:45
Speaker 1: is sort of fascinating. Like sometimes there are some animals
27:48
Speaker 1: that get it from their diet. For example, there are
27:50
Speaker 1: some fish that have red coloration that they get from
27:52
Speaker 1: the animals that they eat, and it just sort of
27:55
Speaker 1: like accumulates in their skin.
27:57
Speaker 2: That would be amazing if humans, for example, change color
28:00
Speaker 2: based on what they ate.
28:02
Speaker 1: Oh man, Yeah, there'd be very specific kinds of diets
28:05
Speaker 1: I imagine, And around Halloween you'd eat like a lot
28:08
Speaker 1: more carrots to get in the mood.
28:10
Speaker 2: Would be great, well, amazing. You could get a tan
28:15
Speaker 2: just by having lunch.
28:16
Speaker 1: That would be incredible and probably a lot safer than
28:18
Speaker 1: what we do now to get tans.
28:20
Speaker 2: All Right, So it turns out that Simon's question is
28:22
Speaker 2: cracked open a huge canyon of unresolved questions in biology.
28:28
Speaker 2: And not only do we not understand dogs, but the
28:30
Speaker 2: whole question of how animals get color is still an
28:33
Speaker 2: active area of research. And maybe having different answers in
28:36
Speaker 2: each species. Amazing.
28:38
Speaker 1: That's right, And so let's see if Simon feels like
28:41
Speaker 1: he learned anything from this answer.
28:44
Speaker 2: It sounds like Kelly read a lot of papers and
28:45
Speaker 2: learned a lot.
28:46
Speaker 1: Kelly read a lot of papers, learned a lot, and
28:48
Speaker 1: also learned that there's a lot that she doesn't know
28:50
Speaker 1: about how this stuff works out. So it was a
28:52
Speaker 1: learning experience for sure.
28:53
Speaker 2: All right, let's hear from Simon. Uh huh.
28:56
Speaker 4: Kelly definitely did learn something, and I think we as
29:00
Speaker 4: the audience, I've definitely learned something too. Thanks Kelly for
29:03
Speaker 4: the great insight into the invisible and incredibly complicated, it
29:08
Speaker 4: seems biological mechanisms behind something as simple as the coloration
29:13
Speaker 4: of our furry friends. I think understanding how it works
29:16
Speaker 4: at this very last step perhaps gives us some insight
29:20
Speaker 4: into how it works at the very first step. So
29:22
Speaker 4: if I go back to the very first cell directly
29:25
Speaker 4: after conceptions, say, where it splits into two, and then
29:27
Speaker 4: to four, and then to eight and so on, eventually
29:31
Speaker 4: giving rise to something that resembles a head, a torso,
29:34
Speaker 4: and four legs, to understand the finer details of how
29:37
Speaker 4: this information has passed down. How one cell knows to
29:40
Speaker 4: be a torso while as a direct neighbor knows to
29:43
Speaker 4: become a leg To understand how this transfer of information
29:47
Speaker 4: works from one cell division to the next will be
29:50
Speaker 4: fascinating to find out one day, But that's a question
29:53
Speaker 4: for another day. Maybe. Thanks Kelly for taking the time
29:56
Speaker 4: to look deeper into this mechanism and give us some
29:59
Speaker 4: insight into this very last step of cell division. Gave
30:03
Speaker 4: up the Great White cause.
30:21
Speaker 2: All right, we're back and we're moving on from the
30:23
Speaker 2: mysteries of biology to the mysteries of the very early universe?
30:27
Speaker 2: Which one do we understand less?
30:30
Speaker 1: Does it really need to be a competition? We don't
30:32
Speaker 1: understand much about anything.
30:33
Speaker 2: Some days it feels like Leonardo wanted to understand the
30:36
Speaker 2: relationship between particle collisions and the Big Bang. Here's his question.
30:41
Speaker 5: Hi, Kelly and Daniel loved the show. I heard particle
30:44
Speaker 5: accelerators being described as tiny banks as in The Big
30:47
Speaker 5: Bang but tiny in another podcast by doctor Katie Mack.
30:52
Speaker 5: I also know we measure the energy of impacts in
30:54
Speaker 5: giga electron votes, so can we also estimate the energy
30:58
Speaker 5: of the Big Bang in electron votes?
31:00
Speaker 6: And?
31:01
Speaker 5: If so, why are we not classifying accelerators in Meli
31:04
Speaker 5: or Fento banks and Easy because the number would be
31:07
Speaker 5: too unsatisfying. Grains from Brazil.
31:10
Speaker 1: All right, So, Daniel, I remember you telling me once
31:13
Speaker 1: that when you all turned on the particle collider for
31:15
Speaker 1: the first time, there was a little bit of a
31:17
Speaker 1: concern that maybe you would destroy the universe? Is that
31:21
Speaker 1: because you all thought you were going to kick off
31:22
Speaker 1: a tiny, big bang.
31:25
Speaker 2: Well, you know, anytime you do something that's never been
31:28
Speaker 2: done before, you don't know what's going to happen. That's
31:30
Speaker 2: the excitement of research, right, you know, you're exploring the unknown,
31:34
Speaker 2: you're potentially unleashing something you didn't expect. And so yeah,
31:39
Speaker 2: there's always a little frison of you know, enthusiasm and
31:43
Speaker 2: fear when that happens.
31:44
Speaker 1: But when I first infect a fish with a parasite,
31:47
Speaker 1: I don't worry that it's the end of humanity. Like,
31:49
Speaker 1: the scale feels very different here.
31:51
Speaker 2: Maybe you should think bigger, Kelly. Yeah, okay, for those
31:53
Speaker 2: of you worried at home, we didn't actually worry about
31:55
Speaker 2: that too much because the collisions we'd do with the
31:57
Speaker 2: particle colliders are not unusual in nature. They're very high
32:01
Speaker 2: energy collisions from particles slamming into the Earth's atmosphere all
32:04
Speaker 2: the time, much higher energy than what we achieve with
32:07
Speaker 2: the large a drunk collider. We didn't worry that we'd
32:09
Speaker 2: be collapsing the Higgs field or creating a black hole
32:12
Speaker 2: or anything like that. But it is a fascinating experiment
32:16
Speaker 2: because we are recreating conditions of the early universe. They're
32:19
Speaker 2: also conditions of our current universe, just not as widespread.
32:24
Speaker 2: And so it's often said that particle collisions recreate the
32:28
Speaker 2: Big Bang, and that's true in some sense, but there's
32:30
Speaker 2: also the potential there to sort of underscore misunderstandings about
32:34
Speaker 2: the Big Bang that we should probably clear up.
32:36
Speaker 1: Well, can we start with, like, what is the defining
32:38
Speaker 1: characteristic of a bang of any size? Small, medium, or large?
32:44
Speaker 2: Yeah, that's a good question. You know, in terms of
32:47
Speaker 2: the Big Bang, the Big Bang is more of a
32:51
Speaker 2: whiff than a bang, right, because the universe is expanding,
32:54
Speaker 2: but it's really sort of cooling. It's becoming older and colder.
32:59
Speaker 2: So the Big Bang is a description of how the
33:01
Speaker 2: universe is decreasing in density as time goes on. It's
33:05
Speaker 2: cooling down and getting more dilute. To run the clock backwards,
33:08
Speaker 2: the universe gets hotter and denser, and we can run
33:11
Speaker 2: backwards to a certain point what we call the plank
33:13
Speaker 2: time beyond which we know our theories don't work, and
33:16
Speaker 2: so everything is a question mark. And that's what we
33:18
Speaker 2: call the Big Bang is expansion from that moment. So
33:21
Speaker 2: it's a description of when the universe had very high
33:24
Speaker 2: energy density. It's not a tiny dot in empty space.
33:28
Speaker 2: The idea of a big bang, especially if you compare
33:31
Speaker 2: to particle collisions, makes it sound like something happening at
33:33
Speaker 2: one location, but the Big Bang was everywhere, and so
33:37
Speaker 2: the similarity between particle collisions and the Big Bang is
33:40
Speaker 2: that both have high energy density. Particle collisions of course,
33:43
Speaker 2: though in just one spot, the Big Bang was everywhere.
33:46
Speaker 1: Got it? Okay? And what kind of scale difference are
33:49
Speaker 1: we talking about in terms of energy between big and
33:52
Speaker 1: tiny bangs?
33:53
Speaker 2: Yeah, so it's a pretty big difference. We compare these
33:56
Speaker 2: things in a weird unit called electron volts, and it's
34:00
Speaker 2: sort of a generic unit of energy. You can also
34:02
Speaker 2: use it to measure mass, because we don't care about
34:04
Speaker 2: things like the speed of light, and so an electron
34:07
Speaker 2: volt is our unit, and to calibrate. For example, a
34:09
Speaker 2: proton has a mass of one giga electron vault, so
34:13
Speaker 2: a billion electron volts is the mass of a proton,
34:16
Speaker 2: and collisions that we can achieve here on Earth are
34:19
Speaker 2: in the scale of ten tarra electron vaults, so ten
34:22
Speaker 2: thousand times the mass of a proton. And that sounds
34:26
Speaker 2: pretty big, right, like ooh wow tarra Like that's a big.
34:30
Speaker 1: Number, But protons are pretty small.
34:32
Speaker 2: Protons are pretty small, exactly, And so the energy of
34:36
Speaker 2: the Big Bang in the same units is ten to
34:38
Speaker 2: the sixteen terra electron vaults, so ten to the fifteen
34:42
Speaker 2: times more energy than the collisions we have at the LHC.
34:46
Speaker 2: And ten of the fifteen is not a small number,
34:49
Speaker 2: you know, it's not fifteen times. It's ten to fifteen
34:53
Speaker 2: ten with fifteen zeros. If your bank account had one
34:57
Speaker 2: with fifteen zeros in it, you'd be very very rich,
35:00
Speaker 2: much much much richer than Elon Musk, probably like Elon
35:03
Speaker 2: Musk squared. So it's very very high energy.
35:07
Speaker 1: If particle physicists had enough money, would you guys try
35:11
Speaker 1: to make a particle collider you could do the Big
35:13
Speaker 1: Bang in because I'm not sure we can trust.
35:17
Speaker 2: You, guys, No, I think we would. And you know,
35:19
Speaker 2: the higher the energy collision, the more stuff you can make.
35:22
Speaker 2: Right we don't know what's out there in the sort
35:24
Speaker 2: of universe's menu of particles. And the incredible thing about
35:28
Speaker 2: these collisions is that you pour energy in and there's
35:31
Speaker 2: some sort of like quantum mechanical magic alchemy that happens,
35:35
Speaker 2: and the universe decides what from its menu to make,
35:38
Speaker 2: and it just sort of picks randomly from all the
35:40
Speaker 2: things that it can make, which means that if you
35:43
Speaker 2: pour enough energy into the collisions, you'll see everything the
35:46
Speaker 2: universe is capable of making. If you do it often enough,
35:49
Speaker 2: you don't even have to know what's out there. So
35:51
Speaker 2: it's like a way to explore the capacity of the
35:54
Speaker 2: universe without even knowing what it's capable of. You don't
35:57
Speaker 2: have to leave your house. It's like, hey, make me
36:00
Speaker 2: everything you can make right here. And as you turn
36:03
Speaker 2: up that energy, you get to explore higher and higher
36:06
Speaker 2: on nature's menu. And you could be just below the
36:09
Speaker 2: threshold and not make the thing because they don't have
36:11
Speaker 2: enough energy, and then you crank up the energy and
36:13
Speaker 2: boom it starts to pop out. So Yeah, we'd love
36:16
Speaker 2: to crank up the energy these things. We're still a
36:18
Speaker 2: factor of ten to fifteen away from the Big Bang,
36:21
Speaker 2: which means there could be particles that were made in
36:24
Speaker 2: the early universe and they're super duper massive and we
36:28
Speaker 2: haven't been able to make them yet. They could be
36:29
Speaker 2: made in collisions of cosmic rays in the atmosphere, but
36:32
Speaker 2: they're very short lived and we don't have detectors up
36:34
Speaker 2: there to see them.
36:35
Speaker 1: So check out Daniels go fundme for the next big
36:38
Speaker 1: particle collider.
36:40
Speaker 2: Leon artists question also asked, can we measure particle collisions
36:43
Speaker 2: in terms of milli or fempto bangs? And the answer
36:46
Speaker 2: is yes. So if you define one bang as ten
36:49
Speaker 2: to the sixteen TeV, then the Large Hadron Collider has
36:52
Speaker 2: collisions at about ten of the minus fifteen bangs or
36:55
Speaker 2: one femto bang, which, yeah, doesn't sound very impressive and
37:00
Speaker 2: not a great way to headline your science funding request.
37:03
Speaker 1: I don't know. I think femto bang sounds pretty.
37:05
Speaker 2: Cool, but it's also a way to sort of trace
37:08
Speaker 2: back the history of the universe. Like as the energy
37:11
Speaker 2: of your collisions goes up and up and up, you
37:13
Speaker 2: recreate conditions that existed everywhere in the universe further and
37:18
Speaker 2: further back in time and already ten TV one. Femto
37:22
Speaker 2: bang is pretty high energy. It takes you all the
37:25
Speaker 2: way back to like microseconds after the Big Bang because
37:28
Speaker 2: the energy started to fall off really really quickly. It
37:32
Speaker 2: becomes more gradual as time goes on. So we are
37:34
Speaker 2: probing conditions in a very very early universe microseconds after
37:39
Speaker 2: the Big Bang.
37:40
Speaker 1: Well, let's see if Leonardo is impressed by femto bangs.
37:45
Speaker 6: Hello, I'm also in teen Kelly, I'm also impressed by
37:48
Speaker 6: fento bank. Also, thanks for clarifying the differences between a
37:53
Speaker 6: particle collider and the early universe. I actually never considered
37:57
Speaker 6: that there could have been particle so massive. If that
38:00
Speaker 6: we will likely never be able to recreate. Thanks.
38:04
Speaker 2: All right, and today we have a special bonus question
38:08
Speaker 2: on gravitational and velocity based time dilation from ASTHMT. We
38:12
Speaker 2: decided we could squeeze in a fourth question for y'all,
38:16
Speaker 2: So here's Ozma's question about time dilation.
38:19
Speaker 7: Hello, I'm a smith, and my question is what would
38:22
Speaker 7: happen to time dialation if both high velocity and strong
38:26
Speaker 7: magnetic feeling interacted simultaneously. Would this cost time to slow
38:30
Speaker 7: down even more significantly or would there be no additional effect?
38:34
Speaker 7: Thank you?
38:35
Speaker 1: All right? So Daniel, I have been listening, well you talk,
38:38
Speaker 1: and I remember you told me there's two kinds of
38:41
Speaker 1: time dilation, gravity and velocity. But my brain is a sieve,
38:47
Speaker 1: so remind me what the difference between those is.
38:50
Speaker 2: Right, So there are two ways that clocks can appear slow. Now,
38:53
Speaker 2: clocks that you hold, that you have with you always
38:57
Speaker 2: run the same speed. But if Kelly gives Zach clock
39:01
Speaker 2: and then shoots them out of a cannon a very
39:03
Speaker 2: high speed relative to her, she will see Zach's clock
39:06
Speaker 2: running slow because velocity time dilation says moving clocks run slow. Now, Zach,
39:12
Speaker 2: with this telescope looking back at Kelly's clock, will disagree.
39:14
Speaker 2: He'll say, no, no, Kelly's clock is running slow. So that
39:17
Speaker 2: kind of time dilation is symmetric, meaning both wiener Smith's
39:22
Speaker 2: see the other one's clock running slow. And at least
39:25
Speaker 2: to this sort of confusion like whose clock is really
39:27
Speaker 2: slower and the answer is there is no really slower,
39:30
Speaker 2: they can argue forever and both be right. So it's
39:33
Speaker 2: sort of a marital trap for the two of them.
39:35
Speaker 1: Yeah, that's not great.
39:37
Speaker 2: But the other kind of time dilation, gravitational time dilation,
39:42
Speaker 2: is asymmetric, which means everybody can agree on it. So,
39:45
Speaker 2: for example, if Kelly does drop Zach near a black hole,
39:49
Speaker 2: she'll see his clock running slower, but he will see
39:51
Speaker 2: her clock running faster. They agree in this scenario, but
39:55
Speaker 2: whose clock is running slower or faster? Both of them
39:58
Speaker 2: see their own clocks running at normal speed. And so
40:01
Speaker 2: the cool thing here, and this is Ozma's question, is like,
40:03
Speaker 2: what happens when you have both? Do they constructively interfered,
40:07
Speaker 2: destructively interfered to his universe? Explode? What happens?
40:10
Speaker 1: I hope The answer is Kelly is right. Whatever time
40:13
Speaker 1: Kelly says is the correct time.
40:18
Speaker 2: The answer is they both contribute. So let's say, for example,
40:22
Speaker 2: that Kelly launches Zach into orbit. Right now, Zach is
40:26
Speaker 2: going really, really fast, and so his velocity means that
40:30
Speaker 2: his clock runs slower than clocks we have here on
40:34
Speaker 2: Earth from our point of view. Okay, but he's also
40:38
Speaker 2: further from the gravitational well of the Earth, so his
40:41
Speaker 2: clocks will run faster than ours. Because of the gravitational
40:45
Speaker 2: time dilation is less so we have actually gravitational time
40:49
Speaker 2: dilation right here on the surface of the Earth. Because
40:51
Speaker 2: of the Earth, we're all experiencing it all the time.
40:54
Speaker 2: Clocks out in deep space run faster. So from Kelly's
40:57
Speaker 2: point of view, Zach's clock runs slower because of velocity
41:01
Speaker 2: and faster because of gravity, and the gravity actually wins out.
41:05
Speaker 2: So the velocity time delation is like seven microseconds per
41:09
Speaker 2: day if he's up with GPS satellites, and forty five
41:13
Speaker 2: microseconds per day the other direction due to gravity. So
41:17
Speaker 2: overall gravity wins.
41:19
Speaker 1: So when I shoot him into orbit, because gravity is
41:22
Speaker 1: winning and it makes things faster, he should still be
41:25
Speaker 1: on time or early to the meetings. I let no
41:27
Speaker 1: excuse for being late, Is that right?
41:30
Speaker 2: I really feel like I don't want to get in
41:32
Speaker 2: the middle of here. Physics is not going to solve
41:35
Speaker 2: your marital.
41:35
Speaker 1: Problems, all right, all right, but baby sandwiches, well.
41:40
Speaker 2: Sandwiches yet well exactly now, from Zach's point of view,
41:44
Speaker 2: both of the effects make Earth's clocks slower. It's fascinating
41:48
Speaker 2: because from the Earth's point of view, we see the
41:49
Speaker 2: effects having different directions. But from Zach's point of view,
41:53
Speaker 2: he sees both effects having the same direction. He sees
41:56
Speaker 2: us moving quickly, which means our clocks run slow, and
41:59
Speaker 2: he sees a closer to a gravitational well of the earth,
42:03
Speaker 2: which means our clocks run slow.
42:05
Speaker 1: Oh see, now, I feel like you're citing with zech.
42:10
Speaker 1: This is no excuse.
42:11
Speaker 2: I feel like I need my lawyer present.
42:15
Speaker 1: All right, everybody, thanks for playing. Just a reminder that
42:17
Speaker 1: you too can send us questions at questions at danielant
42:21
Speaker 1: Kelly dot org. We answer every question, some of them
42:24
Speaker 1: end up on the show and we can't wait to
42:25
Speaker 1: hear from you.
42:26
Speaker 2: And some of our questions come from conversations on the discord.
42:29
Speaker 2: We encourage you to join our discord, where people ask
42:32
Speaker 2: and answer questions and make a bunch of nerdy jokes.
42:35
Speaker 2: You can find the invitation on our website Daniel and
42:37
Speaker 2: Kelly dot org.
42:45
Speaker 1: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We
42:49
Speaker 1: would love to hear from you, We really would.
42:52
Speaker 2: We want to know what questions you have about this
42:55
Speaker 2: Extraordinary Universe.
42:56
Speaker 1: We want to know your thoughts on recent shows, suggestions
42:59
Speaker 1: for future shows. If you contact us, we will get
43:02
Speaker 1: back to you.
43:03
Speaker 2: We really mean it. We answer every message, email us
43:07
Speaker 2: at Questions at Danielankelly dot.
43:09
Speaker 1: Org, or you can find us on social media. We
43:11
Speaker 1: have accounts on x, Instagram, Blue Sky and on all
43:15
Speaker 1: of those platforms. You can find us at D and
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43:19
Speaker 2: Oh be shy right to us