Latest / Daniel and Kelly’s Extraordinary Universe / What causes the biggest explosions in the universe?

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What causes the biggest explosions in the universe? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, do you like looking for shooting stars? I
0:11
Speaker 1: do because sometimes the nice sky is really static, it
0:15
Speaker 1: seems frozen, and so it's exciting to see something streak
0:18
Speaker 1: and flame out across the sky. You know they aren't
0:21
Speaker 1: really stars, right, Um? I am aware, thank you very much.
0:25
Speaker 1: I also know that nobody's actually shooting those stars as
0:29
Speaker 1: far as we know. You know aliens. Hello, you're going
0:33
Speaker 1: to hit the aliens button before me. But it would
0:37
Speaker 1: be cool to actually see a star explode, you know
0:40
Speaker 1: what I mean. You're looking at at the sky and
0:42
Speaker 1: suddenly one of them just goes Yeah, as long as
0:45
Speaker 1: it's not our star, would be pretty fun to watch.
1:04
Speaker 1: Hi am poor handmade cartoonists and the creator of PhD comics. Hi.
1:08
Speaker 1: I'm Daniel Whitson. I'm a particle physicist, and I'm the
1:11
Speaker 1: co author of the book We Have No Idea, A
1:14
Speaker 1: Guide to the Unknown Universe, book about all the things
1:17
Speaker 1: we don't know about the universe. And you wrote it
1:20
Speaker 1: with a really awesome and fun cartoonist, didn't you? I did,
1:23
Speaker 1: in fact, and I was recently contacted by one of
1:27
Speaker 1: our listeners and one of our readers in the Czech Republic,
1:30
Speaker 1: who's reading our book in check, I hope it says
1:33
Speaker 1: the same things. It doesn't English. Well, he actually told
1:35
Speaker 1: me how to translate the title in check literally into English.
1:40
Speaker 1: But how does it translate. Apparently it translates to we
1:43
Speaker 1: don't even know fart about it. Really, the word fart,
1:47
Speaker 1: isn't it? He says. It's a very common expression in
1:50
Speaker 1: check for I don't know fart about that, and that's
1:53
Speaker 1: the expression they chose for the title in check. Wow.
1:56
Speaker 1: I wonder if we had named that, made that the
1:58
Speaker 1: actual title in English, maybe we would assault, we would
2:00
Speaker 1: dislike more copies. I don't know. Maybe the book would
2:03
Speaker 1: kind of stink. But it's a really fun book. It's
2:05
Speaker 1: all about the unanswered questions of the universe, all the
2:09
Speaker 1: things we'd like to know about our lives and where
2:12
Speaker 1: and where we live and how the universe began but
2:14
Speaker 1: don't yet know. And so we hope on this podcast
2:17
Speaker 1: to take you on a tour of what we do
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Speaker 1: and don't know about the universe, and maybe one of
2:21
Speaker 1: you out there, a young budding scientist, will be the
2:23
Speaker 1: one to figure out the answers. That's right. We bring
2:26
Speaker 1: to you all the amazing mysteries of the universe, and
2:28
Speaker 1: all the farts in the universe and all the mysterious
2:31
Speaker 1: farts in the US parts, the ones that fortunately you
2:35
Speaker 1: can't smell through this audio podcast. Well, welcome to Daniel
2:38
Speaker 1: and Jorge Explain the Universe, a production of I Heart
2:41
Speaker 1: Radio in which we examine them the amazing, the mysterious,
2:44
Speaker 1: all the weird and wonderful things in our bonkers universe,
2:47
Speaker 1: and we talk about them in a way we hope
2:48
Speaker 1: entertains you and also teaches you something deep about the
2:51
Speaker 1: physics of our universe. Yeah, we talked about all the
2:55
Speaker 1: sort of a nice and beautiful and wonderful, inspiring things
2:58
Speaker 1: that are out there in universe, the big and the small,
3:01
Speaker 1: but we also talk about some of the crazy things
3:03
Speaker 1: that happened. That's right, because the universe is dramatic and
3:06
Speaker 1: it is violent, and when it wants to make a splash,
3:09
Speaker 1: it goes big, it goes supernova, it goes hyper nova, hypernova. Yeah,
3:16
Speaker 1: So to be on the program, we'll be tackling perhaps
3:19
Speaker 1: one of the most um I don't know, violent or
3:23
Speaker 1: you know, dramatic or you know, maybe interesting events that
3:27
Speaker 1: happened out in the universe. And that happens quite a bit.
3:30
Speaker 1: That's right. It's one of the most interesting and dramatic
3:32
Speaker 1: things that can happen in our universe. One of the
3:34
Speaker 1: things we've seen, the kind of thing that we can
3:37
Speaker 1: even find in historical records that people in ancient times
3:40
Speaker 1: noticed happening in the sky and wondered what it was
3:43
Speaker 1: all about? Right, and then so the question is how
3:46
Speaker 1: much do we know about it? How much do we
3:48
Speaker 1: understand about this incredible event and what we can do
3:52
Speaker 1: if one happens near us? Yeah, and the answer is
3:55
Speaker 1: basically dig a hole and pray. All right, let's get
4:00
Speaker 1: into that. So to be on the podcast will be
4:02
Speaker 1: asking the question what makes a supernova blow explode? I
4:12
Speaker 1: guess super what makes a supernova explode? Or what makes
4:15
Speaker 1: a supernova a supernova? What makes a supernova so super? Yeah? Yeah,
4:21
Speaker 1: why isn't it a super dupernova? Or well, you know,
4:24
Speaker 1: the name nova is actually quite fascinating. It means new
4:28
Speaker 1: and so super. So supernova is like something super and
4:32
Speaker 1: new in the sky. It comes from people looking at
4:34
Speaker 1: the sky and saying, hey, that wasn't there before, or
4:37
Speaker 1: that's different, and it's pretty rare to see something change
4:40
Speaker 1: in the sky. I mean, we're used to the patterns
4:42
Speaker 1: of the seasons and the days and the nights and
4:44
Speaker 1: all that stuff. But otherwise the stars, you know, their
4:48
Speaker 1: lifespan is much longer than ours, and so to see
4:51
Speaker 1: one dies pretty unusual. We'll be talking talking about supernovas
4:54
Speaker 1: and what how what causes a supernova and how that works.
4:57
Speaker 1: But it's basically the biggest explode shin you can have
5:01
Speaker 1: in space? Right? Is that true? The whole universe? That's
5:04
Speaker 1: the biggest explosion that happens. It's the biggest explosion we've
5:07
Speaker 1: seen so far. I mean, the stars are one of
5:10
Speaker 1: the biggest things out there. I guess you can imagine
5:12
Speaker 1: a galaxy exploding, but it's hard to see how that
5:15
Speaker 1: would happen. A galaxy nova. Nobody's ever seen that yet.
5:18
Speaker 1: What would you call that an uber nova or over nova?
5:25
Speaker 1: But I guess maybe it's the biggest explosion because you know,
5:29
Speaker 1: stars are some of the most you know, energy pack
5:31
Speaker 1: things out there, right, I mean that that can explode
5:35
Speaker 1: like you don't see a black hole exploding. You don't
5:37
Speaker 1: yet see black holes exploding. That would be fascinating. And yeah,
5:40
Speaker 1: the key to having a big explosion is not just
5:43
Speaker 1: being massive, having a lot of energy, but releasing it
5:46
Speaker 1: very very rapidly. Right, That's basically what an explosion is.
5:49
Speaker 1: It's like it's like a bomb. You want to deposit
5:52
Speaker 1: a lot of energy and you want to do really quickly,
5:55
Speaker 1: so you got a shock wave of action. And that's
5:57
Speaker 1: the thing that makes supernova is exciting that they happen ly.
6:00
Speaker 1: It also is the thing that makes them hard to
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Speaker 1: understand and hard to spot because we don't know it
6:05
Speaker 1: precisely what causes the star to go supernova, and they
6:08
Speaker 1: don't happen that often, so it's pretty rare to see
6:11
Speaker 1: one's start to go oh wow. Really, we don't know
6:14
Speaker 1: what cosses these supernovas. No, we have some general sense
6:17
Speaker 1: for what happens during the supernova, and we'll dig into
6:20
Speaker 1: it on today's podcast. But what makes it go now
6:23
Speaker 1: and not next week. To predict when an individual star
6:26
Speaker 1: will go supernova is not something we know how to do.
6:29
Speaker 1: Nobody's pressing a switch that you can see. Yeah, they
6:31
Speaker 1: don't annow it's a big countdown like NASA. You know,
6:36
Speaker 1: t's not taking time bomb. No, and astronomers would love
6:40
Speaker 1: to see a star like five seconds before superno, one
6:43
Speaker 1: second before supernova the first moments, you know, that would
6:47
Speaker 1: be fascinating, so you can catch it as it as
6:49
Speaker 1: it's happening. Yeah, And there's actually a guy who was
6:53
Speaker 1: watching the skies in two thousand and sixteen, an astronomer,
6:56
Speaker 1: an amateur astronomer. He was just happen to be looking
6:59
Speaker 1: at one star her through his telescope and he saw
7:02
Speaker 1: it go supernova, like in real time. Wow. What are
7:05
Speaker 1: the chances of that? Well, they're pretty low because it's
7:07
Speaker 1: actually not that many stars that will go supernova, Like,
7:10
Speaker 1: not every star ends up in a supernova. And of
7:13
Speaker 1: course stars lived for a really long long time, and
7:16
Speaker 1: so they calculated the odds is like one in ten
7:19
Speaker 1: million or one in a hundred million that if you're
7:21
Speaker 1: looking at a star or through a telescope, that you'll
7:23
Speaker 1: be watching it go supernova. Oh. So this person was
7:26
Speaker 1: looking at the star through his telescope or her telescope
7:29
Speaker 1: and it went supernova as he was looking at it.
7:31
Speaker 1: As he was looking at it. Now, of course this
7:33
Speaker 1: time delay went supernova a long long time ago, but
7:36
Speaker 1: the images from that supernova arrived on Earth as his
7:40
Speaker 1: eyeballs were pointed at it. Oh wow, And so how
7:43
Speaker 1: did he prove this. Did he have a about his
7:45
Speaker 1: cell phone and took a picture of it? Yea, all
7:49
Speaker 1: good amateur astronomers have cameras attached to their telescopes, so
7:53
Speaker 1: he snapped some photos. Then, of course he alerted astronomers
7:56
Speaker 1: who all pointed their telescopes at it to try to
7:58
Speaker 1: catch a glimpse of the first moment to the star
8:00
Speaker 1: going nova. What is that true? He actually took pictures
8:03
Speaker 1: of it? Oh yeah, Oh wow, that's pretty interesting. Wow.
8:07
Speaker 1: And so supernovas are sort of famous, like people have
8:09
Speaker 1: heard of them. People know that they're a thing. They're
8:11
Speaker 1: pretty dramatic. Their pr campaigns have been pretty good. Yeah,
8:15
Speaker 1: they're there's sort of in the general consciousness for sure,
8:19
Speaker 1: of I think culture and society. I mean, everyone knows
8:21
Speaker 1: him as his stars exploding. Yeah, but I was curious,
8:24
Speaker 1: you know, how much did people actually know about a supernova?
8:27
Speaker 1: Did they know what really happens inside? Do they know
8:29
Speaker 1: what causes it? Do they know whether we understand supernovas?
8:33
Speaker 1: So I walked around campus here at you see Irvine,
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Speaker 1: and I asked folks what they knew about supernovas. Yeah,
8:39
Speaker 1: so think about it for a second. You've probably heard
8:41
Speaker 1: of supernovas, But do you know what causes them and
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Speaker 1: how they actually explode? Here's what people had to say.
8:48
Speaker 1: I guess it's something to do with the star exploding.
8:50
Speaker 1: When a star explodes, What makes it happened? Um, the
8:55
Speaker 1: death of the star. Supernovas usually like an exploding star, right,
9:00
Speaker 1: so what makes its age? Are you going to explode
9:04
Speaker 1: when you get over? Who knows? I know that supermanovas
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Speaker 1: are when a star reaches the end of its life
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Speaker 1: and eventually the force of gravity overcomes the push from
9:15
Speaker 1: the inside of the star and it collapses and then explodes.
9:19
Speaker 1: I know they're in space and it's is it? Is
9:21
Speaker 1: it when a star like implodes or something more? I
9:24
Speaker 1: know that they are the final stage and stars. Okay,
9:28
Speaker 1: what makes it happen? Eventually, the the it becomes too dense,
9:33
Speaker 1: the elements that it creates in the in the middle.
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Speaker 1: At that point it collapses in on itself. And there's
9:39
Speaker 1: a few things that can happen. But a supernova is
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Speaker 1: one of them. A supernova No, I don't alright? Cool,
9:45
Speaker 1: So I think it sounds like everyone knows what it means,
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Speaker 1: Like it means the death or the explosion of a star. Yeah,
9:51
Speaker 1: they knew that it marks the end of the life
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Speaker 1: of a star, but a few people have really a
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Speaker 1: sense for like what's going on inside the supernova? What
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Speaker 1: makes it happen? Why do stars die that way? Why
10:02
Speaker 1: do stars die at all? Why don't they just burn forever?
10:05
Speaker 1: So it's a big e explosion in space. And you're
10:07
Speaker 1: saying it's rare, so only about one to three supernova's
10:11
Speaker 1: per century or something like that in a typical galaxy. Yeah,
10:14
Speaker 1: we have seen a lot of supernovas from Earth, but
10:16
Speaker 1: almost all of them have been in other galaxies. And
10:20
Speaker 1: that's because most stars will not go supernova. In a
10:23
Speaker 1: galaxy like the Milky Way that has about a hundred
10:26
Speaker 1: billion stars, only about one or two, maybe three will
10:30
Speaker 1: go supernova in a hundred years. So it's not it's
10:34
Speaker 1: pretty rare. Most stars don't go supernova. Most stars do
10:38
Speaker 1: not go supernova. The fact that we've seen hundreds is
10:40
Speaker 1: only because there are so many stars and so many
10:43
Speaker 1: galaxies out there. But you know, we're lucky and we're
10:46
Speaker 1: glad actually that they're not a lot of supernovas, because
10:49
Speaker 1: they're pretty devastating. Oh I see, So if a supernova
10:53
Speaker 1: goes off in a galaxy far away, we'll will actually
10:56
Speaker 1: see it, like it'll outshine the whole galaxy and we'll
10:59
Speaker 1: see it, uh, you know, take over the light from
11:02
Speaker 1: the galaxy. That's right. It's a really dramatic event. It
11:04
Speaker 1: can be as bright as the entire sum of all
11:07
Speaker 1: the light from the rest of the stars in the galaxy.
11:10
Speaker 1: And so it's like it like doubles the brightness of
11:13
Speaker 1: a galaxy when it happens. And the most amazing thing
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Speaker 1: is that most of the energy from the supernova doesn't
11:19
Speaker 1: even come out in the form of light, so you're
11:21
Speaker 1: seeing a tiny fraction of this incredible explosion in the
11:25
Speaker 1: visual spectrum. So if you see if you're looking at
11:27
Speaker 1: a galaxy at any point and you see it certainly
11:30
Speaker 1: bright up, it's because of a supernova inside of it,
11:33
Speaker 1: like one of its hundred billion stars went boom. Yeah, precisely. Well,
11:37
Speaker 1: let's get into it, Daniel, all right, um, and explain.
11:40
Speaker 1: Let's explain to people what a supernova is. I guess
11:44
Speaker 1: what's the technical definition of a supernova. Yeah, so technically
11:47
Speaker 1: a supernova is the end of the life of some
11:50
Speaker 1: kinds of stars. Now not all stars. In fact, most
11:53
Speaker 1: stars will not go supernova. But it's essentially the star
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Speaker 1: explodes and it sends out most of the energy that's
12:00
Speaker 1: stored inside of it out into space in the form
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Speaker 1: of electromagnetic radiation, so visible light, which is a tiny fraction,
12:07
Speaker 1: and an enormous number of neutrinos, just like gobs and
12:10
Speaker 1: gobs and gobs of neutrinos, and then also an enormous
12:14
Speaker 1: amount of matter. This is like shock wave of just
12:17
Speaker 1: stuff that gets spewed across the universe, like the shrapnel
12:21
Speaker 1: and the grenade. Yeah, like the shrapnel and the grenade.
12:24
Speaker 1: And it's good that that happens because that goes out
12:27
Speaker 1: and that seeds other stars to form, and it spreads
12:29
Speaker 1: the heavy metals that were burned inside that star out
12:32
Speaker 1: into the universe, so you can get interesting things like
12:34
Speaker 1: a rocky planets then life on them. Well that's interesting.
12:37
Speaker 1: So it's not Supernova is not like an accident that
12:40
Speaker 1: happens to a star. It thought like um, a star
12:43
Speaker 1: is suddenly gets out of balance. It's like it's like
12:45
Speaker 1: in the DNA of the star. You know, like once
12:48
Speaker 1: you once you know what kind of story you are,
12:50
Speaker 1: you will most likely go supernova or if you know
12:53
Speaker 1: the kind of star you know you'll never get you'll
12:55
Speaker 1: never go supernova. Yeah, it's sort of like that, and
12:58
Speaker 1: it's not totally under good, but it's something like if
13:01
Speaker 1: you know how much master is to a star and
13:04
Speaker 1: you know what it's made out of, Like did it
13:06
Speaker 1: start just from burning hydrogen because you're one of the
13:08
Speaker 1: first stars in the universe, or do you already collect
13:12
Speaker 1: the burning remnants of other dead stars and so you
13:14
Speaker 1: have helium and oxygen and nitrogen and carbon and all
13:18
Speaker 1: that stuff already. If you know that starting point, you
13:20
Speaker 1: can almost always predict the life cycle of a star,
13:24
Speaker 1: including whether it's going to become a black hole or
13:26
Speaker 1: a neutron star, or goes supernova, become a white dwarf
13:29
Speaker 1: or whatever. That's basically what determines it is like how
13:32
Speaker 1: big a scoop of stuff did you get of the universe?
13:34
Speaker 1: And what's in that scoop? Wow? And that the terms
13:37
Speaker 1: your your whole life cycle. If you're a star, like
13:40
Speaker 1: you're born and everyone already knows how you're gonna die.
13:44
Speaker 1: Here's a baby. Oh, this baby is going to be
13:46
Speaker 1: a rock star and it's going to you know, shine brightly,
13:50
Speaker 1: but then it's going to go out in a blaze
13:52
Speaker 1: of glory when he or sheet turns thirty two. Stars
13:55
Speaker 1: are not nearly as exciting and variable as people are. Right.
13:59
Speaker 1: They're much bigger, and they're much more dramatic, but they're
14:02
Speaker 1: also simpler, and also they don't really interact with each other.
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Speaker 1: Like a star is pretty isolated. It's got its own
14:07
Speaker 1: little pocket of stuff and it just sits there and
14:09
Speaker 1: burns it until it can't burn it anymore. We know
14:12
Speaker 1: it's gonna go supernova, but you can't predict when it's
14:15
Speaker 1: going to go supernova. Yeah, these stars have some something
14:17
Speaker 1: of a variable lifetime, and you know these events, the
14:20
Speaker 1: supernov event happens really quickly. Remember that the like the
14:23
Speaker 1: time scale for stars can be millions and billions of years,
14:27
Speaker 1: but the supernova events, the time scale for that is
14:30
Speaker 1: days and so days, days, and so it happens really quickly,
14:35
Speaker 1: especially the first bit the explosion. We're talking seconds and minutes,
14:39
Speaker 1: and so what triggers that to happen? Is it like
14:41
Speaker 1: a clock that ticking down. Eventually it's just gonna happen
14:44
Speaker 1: like that. You could predict it a million or a
14:47
Speaker 1: billion years in advance, if you knew well enough. What
14:49
Speaker 1: was happening inside the star or is there some like
14:52
Speaker 1: quantum mechanical randomness that's happening, or is it triggered by
14:55
Speaker 1: some external event, like the star becomes really fragile and
14:58
Speaker 1: then you know, a path seeing shock away from something
15:01
Speaker 1: else makes it go. We just don't really understand those
15:04
Speaker 1: moments or you know, um like a planet falls into
15:08
Speaker 1: it and that triggers it. Perhaps, Yeah, there are stars
15:11
Speaker 1: like that that do get triggers from in falling material,
15:15
Speaker 1: but we don't know exactly like when that happens. All right, well,
15:17
Speaker 1: let's get into the mystery of what triggers supernovas and
15:20
Speaker 1: what's actually happening when they explode. But first let's take
15:23
Speaker 1: a quick break. Right, So we we've seen a couple
15:39
Speaker 1: of these supernovas in the night sky, like without telescopes. Right,
15:43
Speaker 1: there's a historical record of supernovas and in humanity's history. Yeah,
15:48
Speaker 1: it's a big event in the night sky when something blows.
15:52
Speaker 1: And back before people really understood what stars were, they
15:54
Speaker 1: were still interested in looking at them and commenting about them.
15:57
Speaker 1: And so you can go back in the historical record
15:59
Speaker 1: and can find ancient astronomers writing about this and the
16:03
Speaker 1: earliest one. It's called h B nine is from b
16:08
Speaker 1: C and we see this an ancient ancient texts. They
16:11
Speaker 1: talk about the appearance of a new star in the sky.
16:14
Speaker 1: So they just called it HB nine. What were those
16:16
Speaker 1: ancient people thinking they had acronyms and numbers for I
16:20
Speaker 1: don't know, we don't know who was We know it
16:22
Speaker 1: was some unnamed Indian astronomers. We call it h B nine.
16:26
Speaker 1: But you know they wrote about it as a as
16:28
Speaker 1: a new object in the sky. Well, what would we
16:30
Speaker 1: see if if I happened to be looking at the
16:32
Speaker 1: nice guy and a Superno, what just happened to you know,
16:36
Speaker 1: occur while I'm looking at this guy? What would I see?
16:38
Speaker 1: Would I see a star suddenly grow bright and fill
16:42
Speaker 1: the sky with light? Or would just would it just
16:44
Speaker 1: be a star that gets a little bit brighter. Well,
16:46
Speaker 1: it depends on how close it is. Of course, the
16:49
Speaker 1: star is gonna get millions and millions or even billions
16:52
Speaker 1: of times brighter than it normally is. Like, would it
16:55
Speaker 1: be dangerous to look at it? Yes, if you are
16:58
Speaker 1: looking at a star that's going supernova in our galaxy,
17:02
Speaker 1: it could be very dangerous. I mean, you could fry
17:04
Speaker 1: all life on Earth. That's kind of dangerous. So yes,
17:06
Speaker 1: looking at it would be bad, all right, Um, and
17:11
Speaker 1: then what would would I see it go bright for
17:14
Speaker 1: like a few seconds, for a few hours, for a
17:16
Speaker 1: few days. So the light curve of a supernova looks
17:19
Speaker 1: like very rapidly getting brighter and brighter over the period
17:22
Speaker 1: of a few days and then gradually fading over the
17:25
Speaker 1: period of a few weeks outter a few months. So
17:27
Speaker 1: it wouldn't be like a sudden flash. You would get
17:30
Speaker 1: a little bit of warning. You would get brighter and
17:31
Speaker 1: brighter and brighter over a couple of days. Yeah, And
17:34
Speaker 1: you can actually get a warning before the flash arrives
17:37
Speaker 1: because we see neutrinos arrive before the photons. Neutrinos get
17:42
Speaker 1: here first and they tell you watch out a supernova's
17:45
Speaker 1: coming three hours later. Oh really, it's like an early
17:48
Speaker 1: warning system, it is. And you can actually sign up
17:51
Speaker 1: for an early warning emails there instead of neutrino detectors
17:55
Speaker 1: here on Earth, and you can go to a website
17:57
Speaker 1: called s News and they will send you an email
18:00
Speaker 1: when they detect a big flux of neutrinos coming to
18:03
Speaker 1: the Earth. Oh wow, cool, So that you can run
18:06
Speaker 1: outside and not look at it, just so you can know.
18:09
Speaker 1: Man who doesn't want to know, so you can go
18:12
Speaker 1: down down to your bunker and not look up at
18:15
Speaker 1: the sky like our president. It might mean that in
18:17
Speaker 1: three minutes you are that's going to fry. Yeah, it
18:21
Speaker 1: could be. That would be the first warning. And the
18:23
Speaker 1: neutrinos get here first because they're the only ones that
18:25
Speaker 1: can escape the star. Photons, of course, travel faster than
18:29
Speaker 1: neutrinos because neutrinos are not massless like photons are. But
18:33
Speaker 1: neutrinos can fly out of the star, whereas the photons
18:35
Speaker 1: get absorbed inside the star as it's happening, and so
18:39
Speaker 1: photons don't leave the supernova until like the shock wave
18:42
Speaker 1: reaches the surface, which is a few hours after the
18:44
Speaker 1: beginning of the explosion. Yeah, the the the explosion itself. Yeah,
18:48
Speaker 1: they get sort of reabsorbed, and it takes a little
18:50
Speaker 1: while for the photons that will reach Earth to be omitted.
18:54
Speaker 1: So that's why the neutrinos get here first, not because
18:56
Speaker 1: they're faster, but because they sort of left first and
18:58
Speaker 1: didn't get socked. All right, Well, let's get into what's
19:02
Speaker 1: happening here. It's super fun to think about this stuff,
19:05
Speaker 1: you know, because it's a it's a dramatic event, and
19:07
Speaker 1: so people really like thinking not just about how stars
19:10
Speaker 1: form and how they burned, but how they blow up
19:12
Speaker 1: and what makes it happen. And as far as we know,
19:15
Speaker 1: there are sort of two totally different kinds of supernovas
19:18
Speaker 1: that happened. Both of these kinds of supernova reflect this
19:21
Speaker 1: classic Titanic battle between gravity and fusion. In one case,
19:27
Speaker 1: fusion winds and in the other case, it's gravity that
19:30
Speaker 1: comes out on top. The first one we call a
19:32
Speaker 1: runaway fusion, and the second one is probably better well known,
19:36
Speaker 1: is the core collapse supernova. But they're really very different
19:39
Speaker 1: kinds of events. Would you classify them both as supernovas? Like,
19:43
Speaker 1: it's still a star exploding, it just happens in in
19:45
Speaker 1: very different ways. Yeah, And there's lots of different categories
19:48
Speaker 1: of supernovas. You might have heard of type one A,
19:50
Speaker 1: type two, type two C or whatever those described basically
19:54
Speaker 1: what they look like in the sky, what the sort
19:56
Speaker 1: of energy spectrum from them looks like. But there's two
19:59
Speaker 1: fundamental mech isms, this runaway fusion and this core collapse.
20:02
Speaker 1: That's cool, Let's let's get into the first one here
20:05
Speaker 1: runaway fusion. That sounds like um, like an experiment that
20:09
Speaker 1: got away from you. I thought you were gonna say
20:11
Speaker 1: it sounds like a physics based romcom movie, Julia Roberts.
20:15
Speaker 1: So this is what happens when a star. It sort
20:18
Speaker 1: of has like a resurgence. It's a star that's had
20:21
Speaker 1: its day and then sort of died, and then it
20:25
Speaker 1: has a bit of a comeback, really like it had
20:27
Speaker 1: a nice long life as a regular star, and it
20:30
Speaker 1: was already waning, but then it rallied at the end precisely,
20:34
Speaker 1: and it's sort of in retirement and then it sort
20:36
Speaker 1: of brought back for one last explosion. And so what
20:40
Speaker 1: happens here is you have a very normal kind of star,
20:42
Speaker 1: a big star, a red giant. And remember what's happening
20:46
Speaker 1: inside a star is that gravity is pushing in, it's
20:49
Speaker 1: squeezing everything, and because of all that pressure, you're getting fusion.
20:54
Speaker 1: You're turning hydrogen into helium and helium and heavier stuff
20:58
Speaker 1: and heavier stuff into even heavy your stuff. Right, You're
21:01
Speaker 1: you're squeezing stuff together so much it's it's burning and
21:03
Speaker 1: exploding and fusion ng and releasing energy at the same time.
21:07
Speaker 1: That's right. And you might wonder, like, why doesn't an
21:10
Speaker 1: object like that immediately collapse into a black hole. And
21:13
Speaker 1: the reason is that there's outwards pressure and that pressure
21:16
Speaker 1: comes from the explosions, right, it's burning, that's shooting stuff out.
21:20
Speaker 1: And also because matter doesn't like to get squeezed that far,
21:23
Speaker 1: so you know, you squeeze stuff together, it doesn't like
21:26
Speaker 1: to compress, so there's some pressure back out and that's
21:29
Speaker 1: what keeps the star alive. Is this balance between gravity
21:32
Speaker 1: squeezing in and pressure pushing out to keep it alive. Right.
21:37
Speaker 1: It's kind of like if you're squeezing a bag of
21:39
Speaker 1: of of corn kernels, like you would squeeze them, but
21:43
Speaker 1: that would someone would be popping at the same time,
21:45
Speaker 1: so you wouldn't automatically just collapse or explode. You might
21:48
Speaker 1: reach this balance, which is a star. I've heard of fusion,
21:51
Speaker 1: and I've heard of cold fusion, but I've never, until today,
21:54
Speaker 1: heard of corn fusion. I think you might be a
21:59
Speaker 1: brand of pop corn. It's a brand of popcorn physics
22:03
Speaker 1: snacks corn fusions, right, Yeah, there you go. Well, I'm
22:07
Speaker 1: waiting for candy corn fusion. But that's why I think
22:09
Speaker 1: that's what you mean. It's like you squeeze something and
22:11
Speaker 1: then it pops. And so if you have a whole
22:13
Speaker 1: bunch of that and you're squeezing them, David, some of
22:14
Speaker 1: them keep popping until you it's hard to sort of
22:17
Speaker 1: like keep compressing them. I know we're supposed to be
22:19
Speaker 1: talking about supernovous, but now I'm desperately curious. What would
22:22
Speaker 1: happen if you actually squeeze that much popcorn? Would they pop?
22:25
Speaker 1: I bet they would. Bet you'd be heating and pressuring,
22:28
Speaker 1: and uh yeah, you might get a self sustaining corn reaction.
22:34
Speaker 1: That's exactly the idea. And what happens inside the stars
22:37
Speaker 1: that you're fusing the stuff and it's making heavier stuff,
22:40
Speaker 1: and that heavier stuff can then, if you're big enough,
22:43
Speaker 1: and if you're hot enough, can also get squeezed and
22:46
Speaker 1: burned and fused. But as the stuff gets heavier and heavier,
22:49
Speaker 1: you need higher and higher temperatures to keep the reaction going. Oh,
22:53
Speaker 1: I see, at some point you sort of run out
22:55
Speaker 1: of fuel, Right, at some point you can't keep this
22:57
Speaker 1: up forever. You can't keep it up forever. And for
23:00
Speaker 1: some kind of stars, the ones we're talking about red giants,
23:02
Speaker 1: they keep burning until they sort of make carbon, and
23:05
Speaker 1: it's basically like ash, and so it burns all the fuel,
23:09
Speaker 1: but it's not big enough to burn carbon, and that's
23:11
Speaker 1: sort of the end of its life. It's like, Okay,
23:14
Speaker 1: I'm done. I've burned as far as I could, as
23:16
Speaker 1: hot as I could. I reached my pinnacle. Now I'm
23:18
Speaker 1: a big ball of hot carbon. I don't have it
23:21
Speaker 1: in me to make this carbon fuses. It's just not
23:25
Speaker 1: big enough. Like if there were more of it right
23:27
Speaker 1: then there would be enough gravitational pressure to squeeze it,
23:29
Speaker 1: make it hotter and to ignite that carbon, but there
23:32
Speaker 1: isn't and so it just sort of stops there, Okay,
23:34
Speaker 1: and then it sort of cools off. Yeah, and what
23:37
Speaker 1: you have there or something called a white dwarf, which
23:39
Speaker 1: is a fascinating object because it's not fusing anymore. It's
23:42
Speaker 1: just sort of like a big hot lump of carbon,
23:45
Speaker 1: but it's still glowing. It's glowing because it's super duper hot.
23:48
Speaker 1: It's literally white hot carbon. It's glowing in the infrared,
23:52
Speaker 1: are also invisible light. In the visible light, yeah, you
23:54
Speaker 1: can see white dwarfs, but they're not shining because of fusion.
23:57
Speaker 1: They're shining because they're just sort of left overheat from
24:01
Speaker 1: their past life when they were fusing. And my favorite
24:04
Speaker 1: bit about this is that white dwarfs, because there's no
24:07
Speaker 1: more energy coming in there, eventually they're cooling off, and
24:10
Speaker 1: eventually they'll just sort of snuff out and turn into
24:13
Speaker 1: something called a black dwarf. Oh, I see, if you
24:16
Speaker 1: it's red hot, it's white hot, and so that's somebody
24:19
Speaker 1: it can just cool off and it just becomes like
24:21
Speaker 1: a giant ball of rock. Yeah, but that's never happened
24:24
Speaker 1: yet in the universe. We estimate that they would take
24:27
Speaker 1: about ten to the fifteen years, that's how hot this
24:30
Speaker 1: thing is to cool off. But the universe isn't old
24:34
Speaker 1: enough for any black dwarfs to exist. So we have
24:36
Speaker 1: this like category of stars that we haven't sort of
24:39
Speaker 1: achieved yet, haven't unlocked yet as a universe, like a
24:45
Speaker 1: like a video game. Yeah, like a video game, like
24:47
Speaker 1: a video game achievement. I see. So we know what's
24:50
Speaker 1: going to happen to them, but none, none of none
24:52
Speaker 1: of them have actually done it. None of them have
24:53
Speaker 1: actually done it, and some small fraction of them sort
24:56
Speaker 1: of step off that path, right, So you might be thinking, Okay,
24:59
Speaker 1: how's this d up in a supernova? Well, what happens
25:02
Speaker 1: is that some of these guys they think they're at
25:04
Speaker 1: the end of their career, but then they get a
25:06
Speaker 1: sudden dose of extra fuel. To say, for example, you're
25:09
Speaker 1: in a binary star system and you're a white dwarf,
25:12
Speaker 1: and then the other star starts expanding because it gets
25:14
Speaker 1: older and you start sucking up some of its material,
25:17
Speaker 1: or for some other reason, a bunch of new material
25:20
Speaker 1: comes by and you accrete it and you suck it in.
25:23
Speaker 1: Is it that little bit of extra energy or you
25:26
Speaker 1: know gravity, It needs to start cooking that carbon precisely,
25:30
Speaker 1: and so you get enough extra fuel, right, you get
25:33
Speaker 1: all this extra stuff, then you can get hot enough
25:35
Speaker 1: to burn carbon. And what happens then is that it
25:37
Speaker 1: just goes nuts because it's like volatile, like carbon is volatile. Yeah,
25:41
Speaker 1: and this is what we call runaway fusion. It's not
25:43
Speaker 1: like very slowly cooking gently over millions and billions of years.
25:48
Speaker 1: It's like it burns all that really fast, all at once.
25:52
Speaker 1: And in the usual star, you know, you have these
25:53
Speaker 1: shells different temperatures and different densities. You have the heavier
25:57
Speaker 1: stuff in the middle and the lighter stuff on the outside.
26:00
Speaker 1: But here you have basically a ball of carbon with
26:02
Speaker 1: some oxygen in it, and it's just ready to go.
26:04
Speaker 1: And you deposit enough fuel on that thing and it
26:07
Speaker 1: will explode like ten to the forty four jewels, all
26:11
Speaker 1: within just a few seconds. It unbinds the star. It's
26:15
Speaker 1: really incredible. It really literally like blows up from the
26:18
Speaker 1: inside here. Fusion wins and gravity just can't keep the
26:21
Speaker 1: star together anymore. Imagine what would happen if every part
26:25
Speaker 1: of the Earth suddenly had a huge amount of energy
26:28
Speaker 1: like it had, It's enough energy to escape the Earth's gravity. Well,
26:32
Speaker 1: that's what happens to this star, Like every element of
26:35
Speaker 1: the star now has escape velocity from the star. Gravity
26:38
Speaker 1: is overcome and it's just like spews itself over the cosmos.
26:43
Speaker 1: So how does it start. It starts in the middle,
26:45
Speaker 1: like some of the carbon starts to fuse, and then
26:47
Speaker 1: that releases energy with it, which then fuses the carbon
26:52
Speaker 1: in the in the outer layers, and so the whole
26:54
Speaker 1: thing just suddenly has enough energy to fuse and explode. Yeah,
26:59
Speaker 1: and you know, this is sort of the simplified model
27:01
Speaker 1: for what we think might be happening and runaway stars,
27:04
Speaker 1: and we've seen some of them, and but you know,
27:06
Speaker 1: it's hard to really know those first moments because again
27:09
Speaker 1: you can only spot the star after it started to
27:12
Speaker 1: go superno, but we don't know which white dwarfs are
27:15
Speaker 1: about to go. So we really haven't seen the very
27:18
Speaker 1: beginning moments very often, and so it's really difficult to
27:22
Speaker 1: study until compare our simulations to data because it happens
27:27
Speaker 1: within a few seconds. Like it's like it would like
27:30
Speaker 1: be trying to figure out what made a grenade explode
27:32
Speaker 1: or something, because you know, it just explodes. Yeah, it's
27:35
Speaker 1: like if you're looking at a huge field of grenades
27:37
Speaker 1: and you don't know which one is going to explode.
27:40
Speaker 1: All you can do is like snap your neck around
27:41
Speaker 1: as soon as one blows, But then you've missed it.
27:43
Speaker 1: So you never get to see those first moments. And
27:46
Speaker 1: so you might think, well, why don't we just image
27:48
Speaker 1: all the stars all the time, And yeah, I'd love
27:51
Speaker 1: to do that, right, that would be a great strategy.
27:53
Speaker 1: Just as just as signed some grad students to each
27:55
Speaker 1: star in the in the universe, how many grad students
27:58
Speaker 1: do we have, and we do have have some really
28:00
Speaker 1: big survey missions UM that scanned the whole sky and
28:04
Speaker 1: try to spot these things. But again, you can only
28:06
Speaker 1: notice them, you know, after they happen. We'd love to
28:08
Speaker 1: study them just before they happen, so we can see
28:12
Speaker 1: what's causing it, right, because I guess we UM. I mean,
28:16
Speaker 1: they do surveys of the sky that they're always looking
28:18
Speaker 1: at stars, but to get enough of information from the
28:21
Speaker 1: one that blew up is hard because you have to
28:23
Speaker 1: sort of focus on it. Yeah, and you'd love to
28:26
Speaker 1: use our most powerful telescopes. And we have sort of
28:28
Speaker 1: two kinds of telescopes. Ones that are really broad they
28:30
Speaker 1: can image the whole night sky, but they're not that powerful,
28:34
Speaker 1: and ones that can look really deeply at one object,
28:37
Speaker 1: like the hubble, you know, but it can't really scan
28:40
Speaker 1: the whole night sky because it's it has to point
28:42
Speaker 1: really carefully at one thing. I see. So even with
28:45
Speaker 1: the early warning system of the neutrinos, we can't that
28:48
Speaker 1: won't tell us which star is gonna blow. That's what
28:51
Speaker 1: we try to do. We try to see the neutrinos
28:53
Speaker 1: and then like whip stuff around. But you know, neutrinos
28:55
Speaker 1: are hard to spot because even a gazillion of them
28:58
Speaker 1: will come through the Earth and not interact. And you know,
29:01
Speaker 1: new tunion detectors are sometimes busy doing other things, are
29:04
Speaker 1: not dedicated to supernova's. They try to hook these things up,
29:07
Speaker 1: and when the neutrinos tell us the superno is coming,
29:10
Speaker 1: they point in that direction. And so we do our best,
29:12
Speaker 1: because remember, the supernovas have taught us a lot about
29:15
Speaker 1: the universe. They're the ones that gave us the clue
29:17
Speaker 1: that the universe is expanding. All right, So that that's
29:20
Speaker 1: the first way that a star can goes supernova is
29:23
Speaker 1: it's happily retired, but then it gets something triggers it,
29:27
Speaker 1: and it just goes out in a blaze of glory,
29:31
Speaker 1: runaway blaze of glory. That's right. It was saving up
29:34
Speaker 1: for one last hurrah. All right, Let's get into the
29:36
Speaker 1: second way in which supernose can happen, But first let's
29:39
Speaker 1: take a quick break, al right, Daniel. So the second
29:54
Speaker 1: way that uh supernova can happen is called core collapse.
29:58
Speaker 1: And I think this is maybe the one that most
29:59
Speaker 1: peop we're familiar with. Why why is this one? More?
30:02
Speaker 1: I guess popular this is the case where gravity wins
30:05
Speaker 1: in the epics struggle with fusion. I think this one's
30:08
Speaker 1: maybe more awesome. I mean, I don't mean anything negative
30:11
Speaker 1: about runaway fusion the size of a star glowing five
30:15
Speaker 1: billion times brighter than the sun. But this one involves
30:18
Speaker 1: implosion and explosion, so maybe it's like double awesome. Okay,
30:22
Speaker 1: so there's some implosion involved in this one, right, I
30:24
Speaker 1: guess it's in the word core collapse. Yeah. So in
30:28
Speaker 1: this scenario, again, you start as a really big star.
30:31
Speaker 1: You've gotta be our big enough star to even consider
30:33
Speaker 1: going supernova, like a star like our Sun is never
30:36
Speaker 1: going to go supernova. Hey, that's good to know, and
30:40
Speaker 1: be what do you mean big? Like, what's the threshold
30:42
Speaker 1: for supernova? Is it like many times the size of
30:45
Speaker 1: our sun or a little bit more. It's like five
30:47
Speaker 1: to eight times in the mass of the Sun is
30:49
Speaker 1: like the bare minimum you need to have a supernova.
30:52
Speaker 1: Beyond that, you can't even get an agent to return
30:54
Speaker 1: your phone. Yeah, you're forever be list which I think
30:59
Speaker 1: is a good thing. But this sort of core collapse
31:02
Speaker 1: superno requires a really big star. And we were talking
31:05
Speaker 1: earlier about what's happening inside the stars. You have this
31:08
Speaker 1: fusion and you're creating heavier and heavier stuff. Well, in
31:11
Speaker 1: some stars they are big enough to fuse carbon, and
31:14
Speaker 1: then they fuse the byproducts of carbon and make heavier stuff,
31:17
Speaker 1: and the byproduct of that make even heavier stuff. So
31:20
Speaker 1: it's a bigger factory, and it goes beyond what these
31:23
Speaker 1: other stars that we talked about can do. They can
31:25
Speaker 1: actually fuse carbon and and uh and make heavier and
31:29
Speaker 1: heavier elements. But it's sort of a more controlled process
31:32
Speaker 1: because it's happening gradually. It's like an equilibrium. Stuff is
31:35
Speaker 1: slashing back and forth, and the carbon fuses and turns
31:38
Speaker 1: into the next thing. And these guys confuse all the
31:41
Speaker 1: way up to iron. Remember that up to iron, when
31:43
Speaker 1: you have fusion, you release energy. Above iron or nickel
31:47
Speaker 1: or so when you fuse it absorbs energy and so
31:51
Speaker 1: it would cool the star down. So like what comes
31:54
Speaker 1: right before iron. Yes, so iron is number twenty six
31:57
Speaker 1: and nicholas, and that's about as high as you can go.
32:00
Speaker 1: I mean below that you have oxygen at eight you
32:03
Speaker 1: can make you make magnesium a twelve aluminum silicon. Anything
32:09
Speaker 1: below iron, when you fuse it together, releases energy so
32:13
Speaker 1: that that sustains the explosion of the star. But you're saying,
32:18
Speaker 1: after iron, if I want to fuse more things, I
32:20
Speaker 1: have to sink energy into it. Yeah, and so it
32:23
Speaker 1: actually sucks energy out of the star. It starts to
32:25
Speaker 1: cool it. And this is the enemy of the star.
32:28
Speaker 1: The star remembers trying to well, it doesn't like feel
32:31
Speaker 1: anything or want anything. But if a star is going
32:33
Speaker 1: to continue to burn, it needs to exert outward pressure
32:36
Speaker 1: against gravity. But it's sort of working against itself because
32:39
Speaker 1: it's making heavier and heavier stuffed. And so you know,
32:42
Speaker 1: as it's making heavier and heavier stuff, it's making the
32:46
Speaker 1: gravity stronger and more powerful because it's getting denser at
32:49
Speaker 1: its core. And so if you're then also cooling down
32:54
Speaker 1: your own reaction, then you're fighting against yourself. Wow. So
32:58
Speaker 1: and eventually what happens. It winds like you run out
33:01
Speaker 1: of things to fuse. Everything's iron, and then gravity wins. Yeah,
33:05
Speaker 1: eventually gravity wins and it pulls itself together and it
33:10
Speaker 1: collapses and gravity says, all right, I'm blowing past you.
33:14
Speaker 1: And there's this point it's called the Chandra Shaker limit.
33:17
Speaker 1: It's essentially when matter cannot be squeezed anymore. Let's see
33:21
Speaker 1: when all the electrons are pushed down into their lowest orbitals,
33:25
Speaker 1: and everything is tucked as close as possible, and that's
33:28
Speaker 1: what like a white dwarf for a neutron star is
33:30
Speaker 1: sitting at. But when gravity has enough power to overcome that,
33:34
Speaker 1: that electron degenerously. When you have too much stuff, then
33:37
Speaker 1: it collapses and gravity takes over, meaning that um, whatever
33:41
Speaker 1: is keeping the star kind of fluffy, it's no longer enough.
33:46
Speaker 1: Burned too much, and now it's it's too heavy. Yeah,
33:49
Speaker 1: there's not enough outwards pressure and there's growing gravitational pressure inwards,
33:54
Speaker 1: and so eventually gravity just overwhelms it, and that's when
33:57
Speaker 1: you get this core collapse. I guess collapse means that
33:59
Speaker 1: it it's just sort of like folds folds in or
34:03
Speaker 1: what does that mean? Like all the Adams were happy
34:06
Speaker 1: sort of bunched together, but now they crunched in together more. Yeah,
34:09
Speaker 1: and you actually get an inwards going shock wave. And
34:12
Speaker 1: so people sometimes talk about supernovas as implosions and that's why,
34:16
Speaker 1: because you get this shock wave of stuff rushing in
34:19
Speaker 1: towards the center. Wow, because the in the innerts of
34:23
Speaker 1: the star are I guess collapsing before they were sort
34:27
Speaker 1: of fluffy from all the energy. But now they're just
34:30
Speaker 1: they're out of energy, so that everything's just crunching together.
34:33
Speaker 1: To think about the surface of the star, what's happening
34:36
Speaker 1: there is it's constantly getting pulled in by all the
34:38
Speaker 1: heavy stuff inside the star, and it's getting pushed out
34:41
Speaker 1: by the burning. Eventually, if the burning is not strong enough,
34:45
Speaker 1: you know, if it passes this limit, then that stuff
34:47
Speaker 1: gets pulled in and it compresses the next layer, which
34:50
Speaker 1: compresses the next layer, which compresses the next layer. And
34:52
Speaker 1: it's a runaway process because the more you compress something,
34:55
Speaker 1: the higher density it is, the stronger the gravitational force, right,
35:00
Speaker 1: because as you get closer, the gravity stronger. Yeah, so
35:04
Speaker 1: the whole thing just it just falls inwards. It falls inwards,
35:08
Speaker 1: and then what happens depends on how much stuff you
35:11
Speaker 1: started with. And if you're like super duper big, like
35:14
Speaker 1: more than forty times the mass of our Sun, then
35:17
Speaker 1: that's basically it. You just collapse into a black hole
35:19
Speaker 1: without even making a peep. The star just kind of
35:22
Speaker 1: bloop turns into a black hole. Yeah, you can just
35:24
Speaker 1: go and suck itself into a black hole without a supernova,
35:28
Speaker 1: like you can skip the supernova stuff. If you're big, Okay,
35:31
Speaker 1: so that's if you're really big. If you're really big,
35:34
Speaker 1: But if you're not big enough, then the core collapse
35:37
Speaker 1: sort of goes inwards and then it bounces off the hot,
35:40
Speaker 1: dense core of the start, like the shock wave comes
35:43
Speaker 1: in and it reaches a point where the stuff is
35:46
Speaker 1: so dense that it can reflect that shock wave back out,
35:50
Speaker 1: and that's when the supernova happens. That's when like stuff
35:52
Speaker 1: flies out from the star. Oh, it's all this energy
35:56
Speaker 1: of stuff falling in. It's the balance. That's actually the explode. Yes,
36:00
Speaker 1: it's the bounce. And if you're too big, you don't
36:02
Speaker 1: get the bounce, right because it just like turns into
36:05
Speaker 1: a black hole and then nothing can escape. But if
36:07
Speaker 1: you're if you're below that, if you're like around thirty
36:11
Speaker 1: times the mass of the Sun, then you get a
36:13
Speaker 1: bounce that goes out with a supernova and the core
36:16
Speaker 1: becomes a black hole. Oh really, only the core that
36:19
Speaker 1: the other stuff bounces away. Yeah, you get the supernova,
36:22
Speaker 1: this huge shock you know, expus plasma through the universe
36:26
Speaker 1: and neutrinos and light and energy, but the core of
36:29
Speaker 1: it remains and becomes a black hole, and that's different
36:31
Speaker 1: than the other kind of runaway fusion, which didn't form
36:34
Speaker 1: a black hole. That's right, Those don't usually form a
36:36
Speaker 1: black hole. Sometimes those can end with a really dense
36:39
Speaker 1: neutron star, but a lot of times it's just blowing
36:42
Speaker 1: out most of the mass of the star in the
36:44
Speaker 1: runaway fusion. In this case, if you're more than forty
36:47
Speaker 1: times the mass of the Sun, you go straight to
36:49
Speaker 1: black hole. If you're more than thirty times the mass
36:52
Speaker 1: of the Sun, you've got a huge supernova when the
36:54
Speaker 1: bounce turns around and you get a black hole the core.
36:58
Speaker 1: If you're a little smaller than that, it's the same story.
37:01
Speaker 1: Things bounce off the center and then explode down to
37:04
Speaker 1: a supernova, but instead of a black hole the center,
37:06
Speaker 1: and you get a neutron star, which is like a
37:09
Speaker 1: really dense massive material, but not quite dense enough to
37:12
Speaker 1: form a black hole. I see you just you just
37:15
Speaker 1: become a like a compact star. Yes, you just become
37:18
Speaker 1: a really compact blob. And then there's a little window
37:22
Speaker 1: between like seven and ten times the mass of our
37:24
Speaker 1: Sun where um when the gravitational collapse happens. Then it
37:29
Speaker 1: causes runaway fusion and the whole thing just blows um
37:33
Speaker 1: in a huge explosion. So there's all these like pockets
37:36
Speaker 1: like if you're this big, then you'll go supernova if
37:39
Speaker 1: you but if you're a little bit smaller you won't.
37:41
Speaker 1: But then if you're a little bit smaller still you will.
37:44
Speaker 1: Like we said, the fate of the star depends almost
37:46
Speaker 1: entirely on its mass, and so there these little windows
37:49
Speaker 1: like if you're in this window, this happens. If you're
37:51
Speaker 1: in this window, that happens. It's like, oh, man, I
37:53
Speaker 1: shouldn't have eaten that last planet now, now now I'm
37:56
Speaker 1: gonna explode. Literally. Wow, that's interesting. But again, sort of
38:01
Speaker 1: the common thing about all of these scenarios is that
38:05
Speaker 1: it's the it's a collapsing star that becomes a supernova, right,
38:09
Speaker 1: And sometimes it's at the bound. Sometimes it's just it
38:11
Speaker 1: creates a runaway explosion. Yea. For all these core collapse
38:15
Speaker 1: they start with really big stars have been big enough
38:18
Speaker 1: to burn a lot of heavy stuff to go past
38:21
Speaker 1: the carbon limit and uh, and then to pass this
38:24
Speaker 1: gender's say, card limit and collapse gravitationally, right, and then
38:29
Speaker 1: a couple of different things might happen after that. To
38:32
Speaker 1: be a supernova or not. Yeah, you could be black hole.
38:35
Speaker 1: You can be black hole plus supernova. You can be
38:38
Speaker 1: just supernova. You could have as a neutron star. There's
38:40
Speaker 1: lots of different options there, all right, So I guess
38:42
Speaker 1: the next question is should we worry about supernova? Is Daniel,
38:45
Speaker 1: is this something that might happen like with three minute warning,
38:49
Speaker 1: we'll find out that the star next to us is
38:51
Speaker 1: going supernova and then and then goodbye Planet Earth? Or
38:55
Speaker 1: is it unlikely to happen around us? Well, we sort
38:57
Speaker 1: of trying to calculate two different things. One is how
39:00
Speaker 1: close would a supernova have to be to be dangerous?
39:04
Speaker 1: And they figured that if ones within like twenty five
39:07
Speaker 1: light years or so, it would basically destroy half of
39:09
Speaker 1: the Earth's ozone layer, because the half that's facing that
39:12
Speaker 1: star would be fried. And that would be bad because
39:15
Speaker 1: we'd be suddenly like totally exposed to space. An amount
39:17
Speaker 1: of X rays deposited on the planet would like sterilize
39:20
Speaker 1: half the population and or give them cancer instant, Oh
39:23
Speaker 1: my god, within minutes or within days or very quickly. Yeah,
39:27
Speaker 1: I mean, does it really matter if it takes days
39:29
Speaker 1: or minutes to get cancer? You've got cancer. Well, but
39:32
Speaker 1: everything else would stay the same, like a solar system
39:34
Speaker 1: would still be here and we'd be going around the
39:36
Speaker 1: same orbit. Yeah, and you know, that's an interesting question.
39:38
Speaker 1: People wonder if there are gravitational waves from supernova, but
39:42
Speaker 1: we've never seen one before. But it wouldn't affect like
39:45
Speaker 1: the gravity of the Earth. We'd still be orbiting the
39:47
Speaker 1: Sun the same way. Would just be like you know,
39:48
Speaker 1: mostly toast. But fortunately, we've looked around and we haven't
39:52
Speaker 1: spotted anything that we think is going to go supernova,
39:55
Speaker 1: anything anywhere within the nearest five light years. Now, again,
39:59
Speaker 1: we don't have a great understanding of when a stargo supernova,
40:02
Speaker 1: but we think we have a sense for the which
40:04
Speaker 1: kind of star can go supernova, and we don't see
40:07
Speaker 1: any of those nearby. And you know, supernovas are not
40:10
Speaker 1: just bad news, right, supernova is they're sort of part
40:13
Speaker 1: of the life cycle of the galaxy. You know how
40:16
Speaker 1: we learned that forest fires aren't all bad because they
40:19
Speaker 1: helped like clean out dead wood and provide space for
40:22
Speaker 1: new animals. You know, well, they're good as long as
40:25
Speaker 1: you don't live in your house is not next to you. Yeah,
40:28
Speaker 1: exactly that way. It's a sign of a healthy forest
40:31
Speaker 1: to have occasional small fires. In the same way it's
40:34
Speaker 1: a sign of a healthy galaxy to occasionally, know, clear
40:37
Speaker 1: out some of the clutter in the dust and blow
40:39
Speaker 1: up the old stuff and make room for something new.
40:41
Speaker 1: Because that is kind of how um heavier materials like
40:44
Speaker 1: we wouldn't be you and I wouldn't be here if
40:47
Speaker 1: if it's not for a supernova, and it's not just
40:50
Speaker 1: the supernova throw that stuff out into the universe. That
40:53
Speaker 1: is true. But also we wonder about like what makes
40:56
Speaker 1: a star begin, Like give a big cloud of gas
40:59
Speaker 1: and dust. Is gravity just like very gradually pulling it
41:02
Speaker 1: together over billions of years. Some people think that it's
41:05
Speaker 1: the shock wave from a nearby supernova that sort of
41:08
Speaker 1: triggers that gravitational collapse of that cloud into a star.
41:13
Speaker 1: So it might be that the death of a star
41:15
Speaker 1: the supernova is what you need to form new stars.
41:18
Speaker 1: Stars begetting stars. It's all cycle, man, it's the circle
41:22
Speaker 1: of life. Somebody que Elton John, But who who made
41:26
Speaker 1: the first star? Then, Daniel, what came for as the
41:28
Speaker 1: star or the supernova? The eternal question? I believe that
41:32
Speaker 1: one for the philosopher's all right, well, I feel like
41:34
Speaker 1: I learned a lot about supernovas today. You know, I
41:37
Speaker 1: thought that they only did the supernova through core collapse.
41:41
Speaker 1: They didn't know that there were all these other ways
41:43
Speaker 1: that they can happen. Yeah, supernovura fascinating and we're constantly
41:46
Speaker 1: studying them because they are dramatic and they're awesome to
41:49
Speaker 1: learn about, and because we'd like to know, you know,
41:51
Speaker 1: what happens at the end of life of a star.
41:53
Speaker 1: It's it's fascinating, it's dramatic, but it's also still mysterious. Yeah,
41:57
Speaker 1: and it's a big part of how the universe works, right,
42:00
Speaker 1: like how you make metals and everything all around this,
42:05
Speaker 1: everything around us is was basically made in a supernova.
42:08
Speaker 1: Would you say that, like all the metal and components
42:11
Speaker 1: in your phone, in your car, that all came from
42:14
Speaker 1: a supernova. All that stuff was fused inside a hot
42:17
Speaker 1: star billions of years ago. Yes. All right, Well, we
42:21
Speaker 1: hope you enjoyed that. And the next time you look
42:23
Speaker 1: up at the night sky and see something getting brighter,
42:25
Speaker 1: duck or at least close your eyes. At least close
42:29
Speaker 1: your eyes and look it up online later. All right,
42:32
Speaker 1: thanks for joining us, See you next time. Before you
42:43
Speaker 1: still have a question after listening to all these explanations,
42:46
Speaker 1: please drop us a line. We'd love to hear from you.
42:49
Speaker 1: You can find us on Facebook, Twitter, and Instagram at
42:52
Speaker 1: Daniel and Jorge That's one Word, or email us at
42:55
Speaker 1: Feedback at Daniel and Jorge dot com. Thanks for listening,
42:59
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
43:02
Speaker 1: a production of I Heart Radio. For more podcast from
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Speaker 1: my heart Radio, visit the I heart Radio Apple Podcasts,
43:09
Speaker 1: or wherever you listen to your favorite shows. Yeah,