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What are boson stars? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, what does it take to be a star?
0:11
Speaker 1: I think you either have to have enormous natural talent
0:14
Speaker 1: or rich and famous parents. I bet that helps. But
0:19
Speaker 1: what about a star out there in the universe. Oh,
0:21
Speaker 1: that's easier. All you need is like a lot of gas,
0:24
Speaker 1: Like a lot of gas, like the bourbon kind, or
0:27
Speaker 1: the other kind of gas, any kind of gas that
0:31
Speaker 1: kind of make a star out of methane. I don't
0:33
Speaker 1: really know how that would smell, but I bet it
0:35
Speaker 1: would burn pretty well. How about a starman out of
0:39
Speaker 1: laughing gas? That would be pretty funny. I am more
0:58
Speaker 1: handmade cartoonists and the creator of PhD comics. Hi, I'm Daniel.
1:02
Speaker 1: I'm a particle physicist and I'm no kind of star.
1:06
Speaker 1: But I bet you're a gas. I try to make
1:09
Speaker 1: people laugh. Well. Welcome to our podcast, Daniel and Jorge
1:12
Speaker 1: Explain the Universe, a production of our Heart Radio in
1:15
Speaker 1: which we try to gas you up about all the
1:17
Speaker 1: incredible things out there in the universe, the things we understand,
1:21
Speaker 1: the things we don't understand, and the things that scientists
1:24
Speaker 1: are still puzzling over, and the things that make you
1:27
Speaker 1: curious about how our universe works. We try to wrap
1:31
Speaker 1: it all up and ject some jokes and make it
1:33
Speaker 1: all understandable to you. Yeah, because there is a lot
1:36
Speaker 1: out there in the universe to be curious about, including
1:39
Speaker 1: things that may or may not exist. Those are the
1:42
Speaker 1: best things to be curious about. Like is there a
1:44
Speaker 1: tiny little teacup between here in Venus? Yes? Can you
1:49
Speaker 1: prove it? Though I have faith, Daniel in the teacup hypothesis? Well, fortunately,
1:56
Speaker 1: we have better ways of exploring the universe than just faith.
1:58
Speaker 1: We have science, and science encourages us to think creatively,
2:02
Speaker 1: but then ask ourselves questions like how do we know
2:05
Speaker 1: that's true? And how could we approve it? Yeah, because
2:08
Speaker 1: the universe is full of surprises. Sometimes we think some
2:11
Speaker 1: things are impossible, even though the math says that it's possible,
2:15
Speaker 1: and then we find those things out there in the cosmos. Yeah,
2:18
Speaker 1: we have surprises, both experimentally and theoretically. Sometimes we look
2:23
Speaker 1: out into the universe with a new kind of telescope
2:25
Speaker 1: and we see something totally weird than we never expected
2:28
Speaker 1: and didn't understand, like the Fermi bubbles or all sorts
2:32
Speaker 1: of other weird stuff like pulsars. And then there are
2:34
Speaker 1: theoretical surprises where we find something in the math that
2:38
Speaker 1: says this thing could exist in the universe, maybe even
2:41
Speaker 1: should exist. Let's go and see if it's real. Yeah,
2:45
Speaker 1: because I feel like there's no there's nothing in the
2:47
Speaker 1: universe that says that what our expectations are of it
2:51
Speaker 1: or what our experience of it is has to dictate
2:55
Speaker 1: what is actually out there. Thank God for that, right,
2:57
Speaker 1: it's nice that the universe is filled with surprises. It
3:00
Speaker 1: would be borning of the universe was just like the
3:02
Speaker 1: surface of the Earth and not much else. Well, you
3:05
Speaker 1: know that old cars that says, I hope you have
3:07
Speaker 1: an interesting life. Yes, I want to live in interesting
3:10
Speaker 1: scientific times. Actually, I want to live in times when
3:14
Speaker 1: we discover crazy things that totally upend our knowledge of
3:18
Speaker 1: the universe and our understanding of our place in it.
3:20
Speaker 1: That's the power of science. That's the joy of it,
3:23
Speaker 1: is revealing the truth and stripping away our intuition and
3:27
Speaker 1: the ideas that came about just from like living on
3:29
Speaker 1: the surface of the Earth. Well, today we're going to
3:31
Speaker 1: talk about what such thing the scientists think that could
3:34
Speaker 1: be out there. At least the math says it's possible,
3:36
Speaker 1: but we don't really know if it does exist. It
3:39
Speaker 1: would be pretty wild if it does. That's right. It
3:41
Speaker 1: turns out that even though we've talked about neutron stars
3:44
Speaker 1: and magnet oars and crazy white dwarves and all sorts
3:48
Speaker 1: of other kinds of stars. We've done the biggest stars
3:51
Speaker 1: in the universe, the weirdest stars in the universe, it
3:53
Speaker 1: turns out there are even weirder, stranger kinds of stars
3:57
Speaker 1: we haven't even scratched the surface of. So is this
4:00
Speaker 1: the weirdest Star Daniel episode in our Extreme series? This
4:04
Speaker 1: is the most hypothetical list Star I see, I see,
4:07
Speaker 1: the most imaginative star, maybe the most bunkers is Star. Yeah,
4:11
Speaker 1: because each of these sort of extreme examples tells something
4:15
Speaker 1: a little bit about what matter can and cannot do. Right,
4:19
Speaker 1: they're sort of like, you know, extreme examples of where
4:22
Speaker 1: you can take physics. Yeah, these are really useful thought experiments.
4:26
Speaker 1: You say to yourself, is this possible? And if the
4:29
Speaker 1: laws of physics say that it is, then you go
4:31
Speaker 1: out there and you hunt in the universe to see
4:33
Speaker 1: if you find it. And if you find it, cool
4:35
Speaker 1: you've learned something about the universe. And if you don't
4:37
Speaker 1: find it, if you can prove that it doesn't exist
4:40
Speaker 1: somehow that it should exist in the universe, but we
4:43
Speaker 1: don't see any of it. There's a clue, there's a
4:45
Speaker 1: hint that there's something about physics you don't yet understand.
4:49
Speaker 1: And those clues are super valuable because those are the
4:52
Speaker 1: ones that lead us down the path to revealing something
4:55
Speaker 1: true about the universe we didn't know before. Yeah, and
4:57
Speaker 1: that's the whole point of signs, to find out things
5:00
Speaker 1: we didn't know before. What It's not just to make
5:02
Speaker 1: us feel good or make us laugh sometimes, or do
5:05
Speaker 1: you have interesting careers. Science makes me feel good. You know.
5:08
Speaker 1: I had a tasty breakfast this morning because of science.
5:11
Speaker 1: I slept in a warmhouse last night because of science.
5:13
Speaker 1: I'm alive because of science. So, yes, science makes me
5:16
Speaker 1: feel good. I think you mean engineering, Daniel. I don't
5:19
Speaker 1: think a scientists, you know, fix your A C system.
5:22
Speaker 1: This scientist certainly didn't fix my own AC system. That's true. Well,
5:25
Speaker 1: today on the podcast will be asking the question what
5:33
Speaker 1: is a Boson star now, Daniel? That doesn't just refer
5:37
Speaker 1: to the press the button when they discovered the Higgs Boson, right,
5:41
Speaker 1: That would be me. Yes, I'm a star in the
5:43
Speaker 1: Higgs boson. Uh no, I was Did you press the button?
5:47
Speaker 1: I pressed lots of buttons, actually, yes, because I spent
5:49
Speaker 1: time in the control room at the large Hadron Collider,
5:52
Speaker 1: which looks a lot like you know, the way they
5:54
Speaker 1: depict the control room at NASA where they're launching the
5:57
Speaker 1: shuttle or whatever. It's a bunch of monitors and people
5:59
Speaker 1: at desk looking at screens, and you got buttons in
6:02
Speaker 1: front of you, and so yeah, sometimes you actually get
6:04
Speaker 1: to press a button. Yeah, did you press any buttons?
6:07
Speaker 1: Was your role there monitoring the collisions or something? Yeah,
6:10
Speaker 1: you monitor collisions, You make sure the data that's coming
6:12
Speaker 1: in looks reasonable, and then in very rare circumstances, there
6:15
Speaker 1: might be an emergency. I was actually on shift the
6:18
Speaker 1: large hingge On collider when they first turned it on,
6:21
Speaker 1: very early on. It was two thousand eight, if I
6:23
Speaker 1: remember correctly, when we had that accident when there was
6:26
Speaker 1: a spot that was welded poorly and there was an
6:29
Speaker 1: arc and liquid helium was ejected and the whole thing broke,
6:32
Speaker 1: and this this big red button in the control room
6:35
Speaker 1: that you have to hit in the case of an emergency.
6:37
Speaker 1: And I had said at that desk for weeks looking
6:39
Speaker 1: at that button, wanting to press that button, because you know,
6:42
Speaker 1: buttons they have to be pressed right, And so I
6:45
Speaker 1: actually got to press that button. Wow. Now it wasn't
6:48
Speaker 1: just a coincidence that things went wrong when you weren't
6:51
Speaker 1: on the shift. It was a hud of coincidence that
6:54
Speaker 1: things went wrong when I was on shift. Absolutely nothing
6:57
Speaker 1: to do with me at all. It's not like I
6:59
Speaker 1: knocked coffee onto a critical control panel or something. Right
7:03
Speaker 1: with t But yeah, we're asking the question what is
7:06
Speaker 1: a Boson star? And I have to say, I've never
7:08
Speaker 1: heard of this concept a boson star. I mean, I've
7:10
Speaker 1: heard of the Higgs boson, and I think I know
7:12
Speaker 1: what a boson is. It's a kind of particle. But also,
7:16
Speaker 1: but put together with the word star, it's a whole
7:18
Speaker 1: new thing. Yeah. It's fun to just like take two
7:20
Speaker 1: science words and stick them together and say, hey, is
7:23
Speaker 1: this a thing in the universe. I wonder if that's
7:24
Speaker 1: how they came up with this idea. Let's come up
7:26
Speaker 1: with a few quantum black hole that is a thing?
7:30
Speaker 1: Man there, remote dynamic firm me on teleporting hamsters, all right, Yeah,
7:40
Speaker 1: this is an interesting concept in physics. Is it kind
7:43
Speaker 1: of like a new thing, or is it an old
7:45
Speaker 1: thing that people are rediscovering? What's the context here? It's
7:48
Speaker 1: not that old an idea. It's something people have been
7:51
Speaker 1: thinking about in the last few decades, but it's received
7:53
Speaker 1: a little bit of attention recently because one of the
7:56
Speaker 1: ingredients you need to make it a particularly weird kind
8:00
Speaker 1: of Boson has sort of seen a resurgence of interest
8:03
Speaker 1: as a candidate for what might explain the dark matter.
8:06
Speaker 1: All right, well, let's see if people on the internet
8:08
Speaker 1: know what it is. As usual, Daniel went out there
8:10
Speaker 1: and as well, if they knew what a Boson star is. Yeah,
8:15
Speaker 1: and so my deepest gratitude as usual for people who
8:18
Speaker 1: are willing to volunteer to speculate without any preparation on
8:22
Speaker 1: tough physics concepts even Jorge hasn't heard about. So if
8:25
Speaker 1: you would like to participate in the future, please write
8:27
Speaker 1: to me. Two questions at Daniel and Jorge dot com.
8:31
Speaker 1: All right, well here's what people have to say, no idea,
8:35
Speaker 1: the clowns of the star. Do you know there's bosons
8:41
Speaker 1: and fermions. Those are two types of particle. I think
8:45
Speaker 1: one adds up to a different charge and the other.
8:48
Speaker 1: So maybe a boson star is just a start, just
8:50
Speaker 1: completely made out of bosons. That's my best guess. I
8:53
Speaker 1: thought we are done with boson. We find the piggs
8:56
Speaker 1: boson then and that's it. Well and on, No, I
9:02
Speaker 1: don't boson stars. No, sorry, Well I've never heard of them.
9:06
Speaker 1: But my assumption would be that if you can have
9:09
Speaker 1: a star that's only made of neutrons, then you'd be
9:13
Speaker 1: looking at a star that's only made of bosons. However,
9:17
Speaker 1: what that would look like or how it behaves has
9:19
Speaker 1: completely lost all me. Boson stars are stars to give
9:24
Speaker 1: off a lot of bosons, um, and I'm gonna have
9:27
Speaker 1: to back up a few podcasts to remember what bosons are.
9:31
Speaker 1: All right, A lot of good guesses. I like the
9:34
Speaker 1: one about clowns, Like I wonder how many boson stars
9:38
Speaker 1: can you fit into a small car? A lot? Actually
9:41
Speaker 1: a lot. You can seek me a lot of them
9:43
Speaker 1: into there because they're bosons. No. I love hearing these
9:46
Speaker 1: folks try to work it out on the fly. That's
9:49
Speaker 1: my favorite thing about this. It's not like I got
9:51
Speaker 1: your question. I like hearing people think about it and
9:53
Speaker 1: apply their knowledge of physics and try to put these
9:56
Speaker 1: things together and figure it out, you know, in fifteen seconds.
9:58
Speaker 1: So thanks to everybody for your great ideas. Yeah, well,
10:02
Speaker 1: there are a lot of good ideas here. Some people
10:04
Speaker 1: are saying they're stars that give off a lot of bosons,
10:07
Speaker 1: and some people may be saying, we're thinking that there
10:10
Speaker 1: are stars made out of bosons. Could it be a
10:12
Speaker 1: star that eats bosons? Yeah, and there's one person who
10:17
Speaker 1: suggested that maybe neutron stars are made out of bosons,
10:21
Speaker 1: which is a cool idea. Neutron stars are super awesome,
10:24
Speaker 1: but neutrons are not actually bosons. Even though you can
10:27
Speaker 1: have objects we call stars made out of only neutrons,
10:31
Speaker 1: that doesn't qualify as a boson star, but good try.
10:34
Speaker 1: All right, well let's get into it, Daniel, that us
10:36
Speaker 1: three it. What is a boson star? I guess maybe
10:39
Speaker 1: start with the word boson? What does that mean? Yeah,
10:41
Speaker 1: So there are two kinds of particles out there in
10:44
Speaker 1: the universe that we've discovered. There are fermions and there
10:47
Speaker 1: are bosons. And these are not just like cool names
10:50
Speaker 1: for things. These actually have meetings, and the meetings are
10:53
Speaker 1: important because fermions and bosons are very very different kinds
10:57
Speaker 1: of particles. What's the difference. Well, fermions tend to be
11:00
Speaker 1: the kind of particles that make up matter, and bosons
11:03
Speaker 1: tend to be the kind of particles that transmit forces. So,
11:06
Speaker 1: for example, electrons are fermions, Quarks are fermions. Even when
11:11
Speaker 1: you put three quirks together to make a proton or
11:13
Speaker 1: a neutron, you still get a fermion. And so all
11:16
Speaker 1: the stuff that we're made out of, me and you,
11:19
Speaker 1: and amsters and most of the stars in the universe
11:22
Speaker 1: are made out of fermions. Right, So all the matter
11:26
Speaker 1: in the universe are made out of fermions. Were fermion
11:29
Speaker 1: fellas we are, yes, and all the other kind of
11:32
Speaker 1: stuff like light beams and higgs bosons and the weak
11:36
Speaker 1: nuclear force and the strong force. These use particles to
11:40
Speaker 1: communicate between fermions. Like what happens when an electron repels
11:44
Speaker 1: another electron is the exchange a photon. That photon is
11:48
Speaker 1: a boson. So all the particles that represent how matter
11:52
Speaker 1: particles interact, those are force particles. Those are the boson particles.
11:57
Speaker 1: So fermion particles are matter particles, and boson particles are
12:02
Speaker 1: the force particles. Right, So is that the criteria like
12:05
Speaker 1: what they do. Isn't it technically like from a theory
12:08
Speaker 1: point of view that they're all just kind of the same.
12:11
Speaker 1: They're all just like excitations in a quantum field. They
12:14
Speaker 1: are all excitations of quantum fields. But those fields are different,
12:18
Speaker 1: and it's not just about what they do, like what
12:20
Speaker 1: role they serve. They actually have a fundamentally different mathematical
12:24
Speaker 1: structure because all the firm On particles, which are excitations
12:27
Speaker 1: of fer me On fields, have a different quantum spin
12:30
Speaker 1: than all the Boson particles, which are excitations of the
12:33
Speaker 1: Boson field. Remember we talked about quantum spin once in
12:37
Speaker 1: an episode. It's not like that the particles are actually spinning.
12:41
Speaker 1: It's just that they have this property which is really
12:43
Speaker 1: closely related to angular momentum, and so we call it
12:47
Speaker 1: quantum spin. But it's a quantum property which means you
12:49
Speaker 1: can only have a couple of values of it. So,
12:51
Speaker 1: for example, an electron has one half spin can either
12:55
Speaker 1: spin one half up or spin one half down. So
12:59
Speaker 1: for me, on all have these half integer spins half
13:03
Speaker 1: three halves, five halves, whatever. Bosons all have integer spins
13:08
Speaker 1: zero one or two. So if you can go sort
13:11
Speaker 1: of halfway up or halfway down, your fermion, and if
13:14
Speaker 1: you are on the integer number zero, one or two,
13:16
Speaker 1: then you're a boson. So they have different sort of
13:19
Speaker 1: mathematical structures, and that tells us about like the number
13:22
Speaker 1: of different configurations the field can be in. And so
13:25
Speaker 1: fermions and bosons really are fundamentally different kinds of particles.
13:28
Speaker 1: It's like they're part of a different kind of feel altogether, yes,
13:31
Speaker 1: which probably lets them do different things, yes, exactly. And
13:34
Speaker 1: there's a very important property that makes fermions and bosons different. Now,
13:39
Speaker 1: fermions they can't hang out in the same state, like
13:42
Speaker 1: you can't have two electrons hanging out in the same
13:45
Speaker 1: quantum state. You can't have them have the same spin
13:48
Speaker 1: and the same location and the same energy. They just
13:50
Speaker 1: don't get along. They exclude each other. And that's why,
13:54
Speaker 1: for example, when you have a complicated atom with eight
13:57
Speaker 1: electrons around it, for example, they're not all on the
14:00
Speaker 1: lowest energy state. They stack up on top of each
14:02
Speaker 1: other like a game of Connect four. So fermions cannot
14:05
Speaker 1: hang out in the same quantum state, but bosons can.
14:09
Speaker 1: It's the same for quarts, it's the same for quarks. Yeah, absolutely,
14:12
Speaker 1: for any kind of fermion. They will not hang on
14:15
Speaker 1: the same state like this one. In that state, it's done,
14:18
Speaker 1: it's filled in, it's checked off, and the next one
14:21
Speaker 1: that comes in has to settle in at some other state,
14:24
Speaker 1: either higher energy or a different spin or something. But
14:27
Speaker 1: only they're really close together or in the same exact spot.
14:31
Speaker 1: Location is part of your quantum state, And so if
14:34
Speaker 1: you're like isolated in a box, like in a quantum dot,
14:37
Speaker 1: or in a hydrogen atom or something, then the energy
14:39
Speaker 1: level or the spin or something else has to distinguish
14:42
Speaker 1: you from the other electrons. If you're in a different location,
14:45
Speaker 1: that counts as having a different quantum state. But bosons
14:48
Speaker 1: can overlap. Bosons can totally overlap. You can have two
14:52
Speaker 1: bosons in exactly the same quantum state. And you know,
14:56
Speaker 1: for example, take two flashlights and shine them at each other.
14:59
Speaker 1: The phote toons don't like bounce off each other. You
15:02
Speaker 1: can't fill up a room with like light from flashlights
15:04
Speaker 1: and have it be like stuffed full. But fermions repel
15:07
Speaker 1: each other, you know, That's why matter has volume, that's
15:10
Speaker 1: why things fill up. So bosons you can have as
15:13
Speaker 1: many of them as you like in the same state
15:15
Speaker 1: and We've done really interesting experiments that we talked about
15:18
Speaker 1: the podcast, like the bosons dyin condensate, which is an
15:22
Speaker 1: extreme example of this, when you get a huge number
15:24
Speaker 1: of bosons all together in the same quantum state. All right,
15:28
Speaker 1: so then a boson star and then is a star
15:31
Speaker 1: made out of bosons or that gives off the bosons? Yeah,
15:34
Speaker 1: a boson star is a star made out of boson.
15:37
Speaker 1: The Sun, for example, is made out of fermions. It's
15:39
Speaker 1: made out of quarks and electrons all mixed up in
15:42
Speaker 1: different configurations, but they're all fermions, And a Boson star
15:46
Speaker 1: would be a star made out of just boson, like
15:49
Speaker 1: a star made out of light, pure light. Yes, so
15:52
Speaker 1: not every boson is capable of making a Boson star,
15:56
Speaker 1: but yeah, photons are an example of bosons. They're like
15:59
Speaker 1: the most miss kind of boson. But think about sort
16:02
Speaker 1: of how hard it is to make a star. You
16:04
Speaker 1: can't just make a star out of anything. We talked
16:07
Speaker 1: on the podcast about the conditions for making a star.
16:10
Speaker 1: It's actually quite tricky, right, even like stars made out
16:13
Speaker 1: of fermions. You have to have enough mass so that
16:16
Speaker 1: there's gravity that pulls it together and you make like
16:19
Speaker 1: an object not just like a big fluffy cloud out
16:22
Speaker 1: there in the universe. Has to be gravity pulling it together,
16:25
Speaker 1: but there also has to be something else working in
16:27
Speaker 1: the other direction. So gravity doesn't like run away and
16:30
Speaker 1: give you a black hole. In most stars, that's fusion.
16:34
Speaker 1: Gravity comes together and it makes the core of the
16:36
Speaker 1: star really really hot, and so you get light and
16:39
Speaker 1: energy flying out and that pushes against gravity. So the
16:42
Speaker 1: key thing about making a star is this balance. You
16:44
Speaker 1: need something pulling in gravity and you need something pushing
16:48
Speaker 1: out to prevent the collapse. And this is not like
16:50
Speaker 1: an eternally stable thing, so it's not that easy to
16:53
Speaker 1: make it happen. Though in most stars you have fusion
16:55
Speaker 1: and gravity imbalance, and other stars that aren't burning like
16:59
Speaker 1: white dwarf, you know, other weirder stuff happening. But then
17:01
Speaker 1: the question about boson stars is like, what can you
17:04
Speaker 1: get to balance gravity to make a boson star? Right? Well,
17:08
Speaker 1: I guess the tricky part is that you say that
17:10
Speaker 1: bosons are the force particles that transmit forces. So are
17:14
Speaker 1: you talking about like a the idea that you can
17:16
Speaker 1: make a star out of force particles? Like what does
17:21
Speaker 1: that even mean? Daniel, Like a star that where you
17:24
Speaker 1: bring things that are pure force. Yeah, we'll remember that
17:28
Speaker 1: forces aren't transmitted by particles. But those particles can also
17:31
Speaker 1: be real. You know, photons are what electrons used to
17:34
Speaker 1: talk to each other. But photons can also just exist, right.
17:37
Speaker 1: They can fly across the universe, they can be part
17:39
Speaker 1: of a laser beam, and they're created all the time.
17:42
Speaker 1: And so these particles, you know, that's the role they
17:45
Speaker 1: play in our matter and sort of the story we
17:48
Speaker 1: tell about nature, but they can also just exist. So, yeah,
17:51
Speaker 1: you can get a huge pile of bosons all together
17:54
Speaker 1: and then ask questions like what happens to them? Do
17:56
Speaker 1: they form interesting structures? Right? That's the physics game we play.
18:00
Speaker 1: We think what happens when you've got a huge pile
18:02
Speaker 1: of how did yougen together? Oh? Look it does this
18:04
Speaker 1: cool thing. It makes a star. And now people are
18:06
Speaker 1: playing that game, like what happens if you've got a
18:09
Speaker 1: huge number of bosons together? Could you make a star
18:12
Speaker 1: at them? What would they do? Many? Could you fit
18:14
Speaker 1: into a small car? Big fundamental questions? All right, well
18:18
Speaker 1: let's get into how you might actually make a boson
18:21
Speaker 1: star and if they exist, what would they be like?
18:24
Speaker 1: But first let's take a quick break. All right, we're
18:39
Speaker 1: talking about boson stars, a hypothetical, possible, maybe theoretically plausible
18:46
Speaker 1: kind of star, but that maybe we haven't seen yet
18:49
Speaker 1: out there in the universe. We talked about how there
18:52
Speaker 1: are stars that might be made out of bosons. I
18:55
Speaker 1: guess my first question is, how would you even like
18:57
Speaker 1: get a bunch of bosons together? Like, do they have mass?
19:00
Speaker 1: Would gravity bring them together? Or do you need to
19:02
Speaker 1: capture them somehow or you know, lure them with big
19:05
Speaker 1: shoes and red noses? How do we bring them together
19:08
Speaker 1: really comically sized cookies? I think, and that just pulled
19:11
Speaker 1: them all in. No, that's a fair question. You know.
19:14
Speaker 1: You can ask two different questions. One is if I
19:16
Speaker 1: had a huge pile of bosons, would they form a star?
19:19
Speaker 1: And the other question is could I just get or
19:22
Speaker 1: should I expect to see in the universe a huge
19:24
Speaker 1: pile of bosons? Right, it's possible that this thing could
19:28
Speaker 1: potentially exist if you could assemble the ingredients, but that
19:31
Speaker 1: it just doesn't happen in our universe because it's not
19:34
Speaker 1: a consequence of the Big Bang in any way. So
19:36
Speaker 1: those are two totally interesting but separate questions. Oh, I see.
19:40
Speaker 1: One is like can it exist? And the other one
19:43
Speaker 1: is it doesn't exist? Yeah, exactly. And you know, we
19:47
Speaker 1: talked in this podcast about the infinity of the universe
19:50
Speaker 1: and everything that can happen will happen, and that's mostly true.
19:53
Speaker 1: But there's an important coffee out that you had need
19:55
Speaker 1: to have the right initial conditions. You know, it might
19:58
Speaker 1: be that even in an infinite universe, there's no way
20:01
Speaker 1: to start from a hot, dense state that we began
20:04
Speaker 1: from and end up with like a huge pile of
20:06
Speaker 1: bosons all in the same place that then, you know,
20:09
Speaker 1: do whatever they do, maybe make a star. All right, well,
20:12
Speaker 1: let's play the first game. Then what if you suddenly
20:15
Speaker 1: have a bunch of bosons all in the same place
20:19
Speaker 1: or the same vicidity or like volume. What are we
20:23
Speaker 1: talking about? Yeah, that's exactly what you need to do.
20:25
Speaker 1: And you need to think about the two ingredients to
20:27
Speaker 1: make a star. One is gravity and the others outward pressure.
20:31
Speaker 1: So to have gravity, you need to have these objects
20:34
Speaker 1: having some appreciable mass, Right, you need to have gravity
20:38
Speaker 1: be able to work on these things. Now, they're folks
20:40
Speaker 1: out there probably thinking whole lot of second. I know,
20:42
Speaker 1: photons don't have mass, but they are affected by gravity
20:46
Speaker 1: because they can't, for example, escape black holes. And that's true.
20:49
Speaker 1: And we talked once on the podcast about how you
20:51
Speaker 1: could like focus enough photons together to maybe make a
20:54
Speaker 1: black hole, but to make a stable Boson star, you'd
20:57
Speaker 1: actually need to have a particle with at least little
21:00
Speaker 1: bit of mass, so gravity has like a little bit
21:02
Speaker 1: more of a handle to pull it together, right. Well,
21:06
Speaker 1: But it isn't like mass the same thing as energy, Like,
21:09
Speaker 1: if I have a lot of photons in one place,
21:11
Speaker 1: wouldn't that warp the space around it just like it
21:14
Speaker 1: as if it had a lot of mass. Yeah, absolutely would.
21:17
Speaker 1: And you could, for example, make a black hole if
21:20
Speaker 1: you concentrated photons together enough. But a star is a
21:23
Speaker 1: little bit different. It's actually harder to make than a
21:25
Speaker 1: black hole. Black hole is just like a bunch of
21:27
Speaker 1: energy in a super tiny space. A star is a balance, right,
21:31
Speaker 1: It has to be a balance to have just the
21:33
Speaker 1: right amount of gravity and just the right amount of
21:35
Speaker 1: outward pressure. So these two things match, And the calculations
21:39
Speaker 1: just don't suggest that photons could make a Boson star.
21:43
Speaker 1: They don't have enough mass to like pull together in
21:45
Speaker 1: the right density to get the outward pressure you need.
21:49
Speaker 1: I see. I think what you're saying is that for
21:50
Speaker 1: something to be called the star, I mean, it can't
21:53
Speaker 1: be a black hole basically, and it can't be an
21:55
Speaker 1: explosion either. It has to like shine and shine consistently.
21:59
Speaker 1: And you're saying thing that you just can't do that
22:01
Speaker 1: with bosons, like they wouldn't stick together if they don't
22:04
Speaker 1: have mass. You can't do that with photons. There are
22:07
Speaker 1: other bosons out there that might be candidates for making
22:10
Speaker 1: a boson star, but we don't think that photons can
22:12
Speaker 1: do all right, So which bosons could do it? Well,
22:15
Speaker 1: let's go through the kinds of bosons there are in
22:18
Speaker 1: the universe. What's on the menu next up our gluons.
22:22
Speaker 1: But gluons also have no mass. We've got to scratch
22:25
Speaker 1: them off. We also need a particle that's stable. We
22:29
Speaker 1: don't want our boson start to decay instantaneously into other
22:32
Speaker 1: kinds of stuff, and so that, for example, removes Higgs bosons.
22:36
Speaker 1: Higgs bosons exist in the universe, but very very briefly,
22:40
Speaker 1: they very rapidly decay into pairs of fermions, like a
22:43
Speaker 1: Higgs will decay into two bottom corks or into two
22:46
Speaker 1: muans or something like that. So we need a stable particle.
22:49
Speaker 1: So we don't think there are any Higgs stars out there,
22:52
Speaker 1: which is too bad because that would be kind of awesome. Yeah,
22:55
Speaker 1: pretty good name recognition right there. And so that removes
22:59
Speaker 1: the possibility of a Hig star and also a W
23:02
Speaker 1: star or a Z star. WS and zs are the
23:06
Speaker 1: bosons associated with the weak nuclear force, and they're also
23:09
Speaker 1: very massive and they decay very quickly. Z s decay
23:12
Speaker 1: into a pair of corks. Ws decay also into a
23:15
Speaker 1: pair of corks or sometimes into leftons, and so you
23:18
Speaker 1: just can't make them out of those particles because they
23:20
Speaker 1: would just decay into a Meon star. Well, I'm sad
23:23
Speaker 1: that we can't have gluon stars, but we have glue balls. Actually,
23:27
Speaker 1: glue balls are a stable configuration of just gluons, a
23:30
Speaker 1: particle made out of just gluons, which is pretty but
23:34
Speaker 1: you can't have a gluon star unfortunately. Yeah. Also that's
23:38
Speaker 1: a sticky subject. So what does that leave us, which particle,
23:42
Speaker 1: which boson particle could we used to make a Boson star. Well,
23:46
Speaker 1: that basically crosses off all the bosons that we know exists.
23:49
Speaker 1: So all right, we're done, but we're not done because
23:55
Speaker 1: there are always more particles on the list, this long,
23:57
Speaker 1: infinite list of hypothetic goal particles, particles that we think
24:02
Speaker 1: might exist and if they did, could do other weird
24:06
Speaker 1: things that the particles were familiar with don't do. And
24:09
Speaker 1: near the top of that list is a particle which
24:12
Speaker 1: has gotten a lot of attention recently. Theoretically, it's called
24:16
Speaker 1: the axion. Yeah, we had an episode about that. Maybe
24:20
Speaker 1: remind folks what an axon is, And by folks I
24:23
Speaker 1: mean including myself. Well, an axon is named after a
24:27
Speaker 1: detergent because it was thought up by Frank Wilcheck and
24:29
Speaker 1: he was doing a grocery shopping while he was thinking
24:31
Speaker 1: about the name, and there's a detergent called axon, and
24:34
Speaker 1: he thought, oh, that's a cool name. So the axon
24:37
Speaker 1: particle is one that was thought up to sort of
24:39
Speaker 1: explain a theoretical puzzle in the strong force. People didn't
24:44
Speaker 1: really understand why the strong force was different from the
24:46
Speaker 1: weak force in a subtle way, and so they came
24:49
Speaker 1: up with this axion to explain it. But the reason
24:51
Speaker 1: that axons are interesting recently is that people think they're
24:54
Speaker 1: a good candidate for what might be the dark matter particle.
24:58
Speaker 1: Remember that while we no dark matter is a thing,
25:01
Speaker 1: we know it's out there. We know it's providing gravity.
25:04
Speaker 1: Most of the gravity in the universe actually comes from
25:07
Speaker 1: dark matter. We still don't know what it's made out of.
25:10
Speaker 1: It could be made out of one particle, or many particles,
25:14
Speaker 1: or some other weird kind of stuff. But we have
25:16
Speaker 1: this sort of list of candidates. One of the particles
25:19
Speaker 1: on that list is a firmion. It's called the WHIMP,
25:21
Speaker 1: the weekly interacting massive particle, and it's sort of the
25:24
Speaker 1: leading candidate for a long time, but nobody's founded. We
25:27
Speaker 1: have all these dedicated experiments looking for whimps and not
25:31
Speaker 1: seeing them. So recently people have been charted, I think
25:33
Speaker 1: a little more broadly, dig deeper into that bag of
25:36
Speaker 1: hypothetical particles to find other things. And the idea that
25:39
Speaker 1: the axion might be the dark matter is sort of
25:42
Speaker 1: popular these days. Wow, alright, I'm a little confused now.
25:46
Speaker 1: So you're saying that dark matter could be made out
25:49
Speaker 1: of something that's not matter, that's a force a force particle,
25:54
Speaker 1: and that's an axion, and that if these things exist,
25:58
Speaker 1: you could potentially put them together to make an action star. Yes, exactly.
26:02
Speaker 1: You totally understood it, so it must have been perfectly clear.
26:05
Speaker 1: So we don't know that acidons exist, right, it's an idea.
26:08
Speaker 1: It would be sort of beautiful theoretically and solvement of
26:10
Speaker 1: interesting problems. If you're interested in that, go dig into
26:13
Speaker 1: that podcast episode specifically on that topic. We don't know
26:16
Speaker 1: that they exist, but they would solve an interesting theoretical
26:19
Speaker 1: problem about the strong force. They might also be dark matter,
26:22
Speaker 1: and yes, they would be the perfect ingredient for making
26:25
Speaker 1: a Boson star because they are boson and they have
26:28
Speaker 1: a little bit of mass and they are stable. Hey
26:33
Speaker 1: did I tell you that Frank will Chick retweeted me
26:35
Speaker 1: the other day or mentioned being a tweet. I didn't
26:39
Speaker 1: know that. I didn't even know he tweeted you. I
26:41
Speaker 1: felt like an action star my cell there for a
26:43
Speaker 1: moment there, alright. So then if a Boson star exists,
26:48
Speaker 1: it would be potentially made out of actions, which is
26:52
Speaker 1: you're saying are stable and they do last for a while,
26:55
Speaker 1: and they do have mass, and so they could get
26:57
Speaker 1: sort of bunched together by gravity. Yeah, that's the requirements
27:00
Speaker 1: to be the dark matter, right, you need to have
27:02
Speaker 1: mass otherwise you can not explain in the dark matter.
27:05
Speaker 1: And you need to be stable on cosmological time scales,
27:07
Speaker 1: because we think dark matter sticks around a long time
27:10
Speaker 1: and still here after all. So axions satisfy both of
27:13
Speaker 1: those requirements. And then you have to ask the question like, well,
27:16
Speaker 1: what makes it a star? And I heard you saying earlier, like, well,
27:20
Speaker 1: it has to shine. And I know we've talked on
27:22
Speaker 1: this podcast before about the definition of a star versus
27:25
Speaker 1: a planet, and a star is defined to be something
27:27
Speaker 1: that has fusion happening at its core. Here though, unfortunately
27:31
Speaker 1: we're gonna have to be inconsistent and relax that definition
27:34
Speaker 1: because a boson star doesn't actually shine. How convenient. So
27:40
Speaker 1: what are we talking about then? That Like, if you
27:41
Speaker 1: get a whole bunch of axons together, then gravity would
27:46
Speaker 1: keep them in a in a ball of axions, like
27:49
Speaker 1: a sphere of acions. What what would happen if I
27:52
Speaker 1: get a bunch of them together? But like, even even
27:54
Speaker 1: if I get two of them together, do they attract
27:55
Speaker 1: each other by gravity? They would attract each other with gravity. Now,
27:58
Speaker 1: just two particles would have infinitesimal gravitational force, And so
28:02
Speaker 1: that's why we don't think about gravitationally bound particle systems. Right,
28:06
Speaker 1: Like the proton and the electron, the gravitational force between
28:09
Speaker 1: them is basically zero. We should compare to the other forces.
28:13
Speaker 1: But if you have a lot of axions near each other,
28:15
Speaker 1: then yeah, you're going to have a lot of mass
28:17
Speaker 1: and that will make a gravitationally bound system. And so
28:20
Speaker 1: you can get a huge serving of axions and they
28:23
Speaker 1: would clump together and they would fall into each other,
28:26
Speaker 1: and then you have to ask the question, well, like
28:27
Speaker 1: why wouldn't you just make a black hole? Right? Remember,
28:30
Speaker 1: a star has to have two conditions, needs to have
28:33
Speaker 1: gravity to clump it together, and it needs to have
28:36
Speaker 1: something to resist falling into a black hole. The reason
28:39
Speaker 1: why our son is not a black holes because it's
28:41
Speaker 1: resisting that through fusion. The reason that white dwarfs, which
28:45
Speaker 1: is the future of our Son, aren't black holes is
28:47
Speaker 1: not because they're burning. It's because they're actually made out
28:50
Speaker 1: of fermions. And those fermions don't want to sit on
28:53
Speaker 1: top of each other. Right, Fermions have this exclusion principle,
28:57
Speaker 1: and so that's like quantum mechanics at work there, and
29:00
Speaker 1: that white dwarfs don't fall into black holes is because
29:03
Speaker 1: of quantum mechanics of their fermions. But axons are different.
29:07
Speaker 1: Bosons are different. They can't do either of those things.
29:10
Speaker 1: They can't make fusion to have radiation pressure. They can't
29:14
Speaker 1: rely on the poly exclusion principle because that only applies
29:16
Speaker 1: to fermions, meaning like if you get a bunch of
29:19
Speaker 1: electrons at some point they'll repel each other, or protons
29:22
Speaker 1: or you know, balls of dirt or neutrons. Yeah, I
29:25
Speaker 1: like to make a planet, but bosons they can't sit
29:28
Speaker 1: on top of each other. So I guess if you
29:30
Speaker 1: get a whole bunch of them together, why wouldn't they
29:32
Speaker 1: just all sit in the same point. That's kind of
29:35
Speaker 1: what you're saying, right, And if they do, then you
29:37
Speaker 1: would form a black hole exactly. So you need a
29:39
Speaker 1: boson which would prevent itself somehow from collapsing. And the
29:43
Speaker 1: way you do that here is another property of quantum mechanics.
29:47
Speaker 1: So you're exactly right there. The reason a neutron star
29:50
Speaker 1: and a white dwarf don't collapse into a black hole
29:53
Speaker 1: is because the fermi pressure. Right, it's all these particles
29:55
Speaker 1: not wanting to sit on top of each other. Boson
29:57
Speaker 1: stars can't do that. But there's an another property of
30:00
Speaker 1: quantum mechanics, the uncertainty principle, that just prevents axions and
30:04
Speaker 1: bosons from being too constrained. Right, if you have a
30:09
Speaker 1: bunch of axions and say they're all within the same
30:12
Speaker 1: sort of location, then that creates a large uncertainty on
30:15
Speaker 1: their position, because the uncertainty principle tells us that there's
30:19
Speaker 1: like a minimum amount of uncertainty in the momentum and
30:22
Speaker 1: the position of these particles. So if you can strain
30:25
Speaker 1: their position and their momentum becomes uncertain and then they
30:27
Speaker 1: fly off, the quantum mechanics sort of resists having these
30:31
Speaker 1: things collapse. What do you mean They can't merge like
30:33
Speaker 1: they can be used together like fermions. Well, not all
30:36
Speaker 1: fermions confuse together, only some, only some, but yeah, but
30:40
Speaker 1: bosons typically don't interact with themselves, like photons don't interact
30:45
Speaker 1: with other photons. Photons don't merge together to form something else.
30:49
Speaker 1: Some bosons do, like gluons or higgs. Bosons have a
30:52
Speaker 1: self interaction, but most bosons, including axions, don't interact with themselves.
30:57
Speaker 1: They just like don't even see each other, and unlike
31:00
Speaker 1: add up, Like if you have two in the same spot,
31:02
Speaker 1: don't they just add up. They don't add up because
31:03
Speaker 1: they don't like fill energy levels. Right, they can all
31:06
Speaker 1: be in the same energy level. That's not a problem
31:08
Speaker 1: for bosons, and they don't have any interaction. You know
31:11
Speaker 1: that field, the axon field doesn't interact with itself at all,
31:15
Speaker 1: just the same way photons don't. Photons, for example, only
31:18
Speaker 1: interact with charge particles. Right. They will ignore neutrons and
31:22
Speaker 1: neutrinos and anything else that has zero electric charge, including
31:26
Speaker 1: their photons, and axions are the same way they ignore
31:29
Speaker 1: all other axon. If I have two photons in the
31:32
Speaker 1: same spot, then they just become a bigger photon or
31:34
Speaker 1: are they still technically to fold doon, there's still two photons. Yeah,
31:38
Speaker 1: And I should add here that there are actually a
31:40
Speaker 1: few different flavors of axons, since they are a hypothetical particle.
31:45
Speaker 1: Right now, we're talking about the ones that don't interact
31:48
Speaker 1: with themselves or with photons, But there are other versions
31:52
Speaker 1: of these theories where they have some small self interaction
31:56
Speaker 1: and they can feel photons a little bit. Those variants
31:59
Speaker 1: can also make boson stars, and sometimes that self interaction
32:03
Speaker 1: can help if it's repulsive, because the axons might repel
32:07
Speaker 1: each other and then form that outward pressure to keep
32:10
Speaker 1: the axon star from collapsing. All right, well that's our
32:14
Speaker 1: main imaginary candidate for these imaginary stars, the axon, and
32:19
Speaker 1: so that's how you would make one. But let's talk
32:21
Speaker 1: about whether or not we actually see them out there
32:24
Speaker 1: in space and what they would be like. But first,
32:27
Speaker 1: let's take another quick break a right. We're talking about
32:42
Speaker 1: boson stars that may exist out there in the cosmos,
32:46
Speaker 1: and if they do, they might be made out of axons,
32:49
Speaker 1: which themselves may or may not exist. I feel like
32:53
Speaker 1: we're stacking imaginaries here. The imaginary concepts exclude each other, Daniel,
32:58
Speaker 1: do they add up? Confused? Can they merge? These bonkers
33:02
Speaker 1: concepts are all boson, so we can have an infinite
33:04
Speaker 1: number of bonkers nous. I see, they don't exclude each other,
33:07
Speaker 1: so you can just stack him infinitely exactly until we
33:10
Speaker 1: get a bozo star. All right, Well, let's say that
33:13
Speaker 1: the axion does exist, and let's say that you could
33:16
Speaker 1: somewhere out there and get them all together enough to
33:20
Speaker 1: make some sort of axon object. That still doesn't tell
33:23
Speaker 1: me how that makes it a start, Like, why isn't
33:25
Speaker 1: wouldn't be called an axion planet or an axion you know, Well,
33:32
Speaker 1: if you were around when they were deciding on the
33:34
Speaker 1: name of these things, then that would have been a
33:36
Speaker 1: good idea axion planet. I think that makes more sense,
33:39
Speaker 1: you know, because the planet is a nonfusing blob of
33:43
Speaker 1: stuff out there in the universe made out of basically whatever.
33:47
Speaker 1: So yeah, these axions are also they're not fusing, they're
33:50
Speaker 1: not glowing, they're not giving off any light. They're just
33:53
Speaker 1: a stable collection of axions that are resisting collapsing into
33:57
Speaker 1: a black hole. So I think they called it a
34:00
Speaker 1: star just to sort of make it sound awesome, not
34:04
Speaker 1: because it's actually doing it really? Was that a in
34:08
Speaker 1: the physics paper in there, I don't know. I mean,
34:10
Speaker 1: in the same way our neutron stars stars, right, they're
34:14
Speaker 1: just a big collection of neutrons that aren't collapsing into
34:16
Speaker 1: a black hole yet. But they're not glowing, right, They're
34:19
Speaker 1: not using there's no radiation being emitted there. So the
34:23
Speaker 1: same way like white dwarfs, right, we call those stars.
34:26
Speaker 1: So yeah, astronomy has got support to do. I think
34:29
Speaker 1: what you're saying. That is it? In physics, there are
34:31
Speaker 1: no standards for being a star. Anyone can be a star.
34:34
Speaker 1: It's like our society today. You need an Instagram account. Yeah,
34:37
Speaker 1: for famous parents. Being a physicist is easy. It's no
34:40
Speaker 1: big deal. No, I'm saying, I cannot defend the naming
34:43
Speaker 1: of this thing as a star. It's just there's nothing
34:46
Speaker 1: I can say about it, and that makes any sense.
34:48
Speaker 1: But I guess you're saying that it is possible theoretically
34:51
Speaker 1: to have a whole bunch of axons together in the
34:54
Speaker 1: same spot without collapsing into a black hole. And what
34:57
Speaker 1: keeps them from collapsing? Is this on certainty principle? He said, yeah, exactly.
35:02
Speaker 1: As he's trying to constrain them to be in a
35:03
Speaker 1: smaller and smaller location, the uncertainty grows on their energy,
35:07
Speaker 1: and that essentially resists them being constrained. So the uncertainty
35:11
Speaker 1: principle resists them from being collapsed too far into a
35:15
Speaker 1: tiny little spot. So how big would an actium planet
35:19
Speaker 1: evolve be? Like, if you get a whole bunch of
35:21
Speaker 1: them together, would it be just super tiny or would
35:24
Speaker 1: it actually be the size of a planet. It's a
35:26
Speaker 1: great question, And it depends on the mass of the
35:28
Speaker 1: boson star, and so a more massive boson star would
35:32
Speaker 1: be larger have a similar sort of structure two black holes,
35:35
Speaker 1: right or more massive black hole than just becomes larger
35:39
Speaker 1: and larger and larger sort of in volume. And so
35:41
Speaker 1: boson stars in the same way would resist collapsing. And
35:44
Speaker 1: the more bosons you have, the more resistance there is,
35:47
Speaker 1: and so they would just sort of like grow larger
35:49
Speaker 1: and larger. But the question is, like, you know, are
35:51
Speaker 1: there boson stars and if so, how big are they? Yeah,
35:55
Speaker 1: because I feel like you're saying that the it's the
35:57
Speaker 1: uncertainty principle that keeps him kind of from collapsing. Can
36:02
Speaker 1: you have an uncertainty principle the size of a planet,
36:04
Speaker 1: like that's a big ball of uncert is a big
36:07
Speaker 1: ball of uncertainty, Yeah, exactly. But you know it also
36:10
Speaker 1: applies locally and not just globally, so you can have
36:13
Speaker 1: like patches of these things where you have bosons lying
36:16
Speaker 1: on top of each other. So yeah, I think it
36:18
Speaker 1: certainly could apply to something the size of a planet.
36:21
Speaker 1: I mean it does also for white dwarves righting, for
36:24
Speaker 1: neutron stars, there you have, like quantum mechanics at work
36:27
Speaker 1: preventing particles from overlapping on top of each other, providing
36:30
Speaker 1: the resistance to collapsing into a black hole. Does that
36:33
Speaker 1: apply to photons to like? Can photons also be stacked
36:37
Speaker 1: like that? Does the uncertainty principle also prevent photons from
36:40
Speaker 1: being on top of each other? Yeah? Absolutely. If you
36:42
Speaker 1: try to localize photons in the same way, then it
36:46
Speaker 1: will prevent you from knowing their energy in exactly the
36:48
Speaker 1: same way. The uncertainty principle applies to all quantum particles.
36:51
Speaker 1: It might be easier to understand the uncertainty principle if
36:54
Speaker 1: you think about it in terms of temperature. Quantum mechanics
36:57
Speaker 1: prevents anything from going to absolute zero temperature because there's
37:01
Speaker 1: always a minimum energy. Otherwise you'd know a particle's momentum
37:05
Speaker 1: and location at once because it'd be frozen in place.
37:08
Speaker 1: So there's a minimum temperature for any collection of particles.
37:11
Speaker 1: And that's quantum mechanics keeping something from collapsing into a
37:15
Speaker 1: single dot. So the way you, for example, you would
37:17
Speaker 1: make a black hole out of photons is not by
37:21
Speaker 1: trying to squeeze a bunch of photons that already exist
37:24
Speaker 1: into the same location, but by overlapping laser beams on
37:27
Speaker 1: top of each other, the photons from different directions are
37:30
Speaker 1: all coming together in the same place. Well, let's say
37:32
Speaker 1: that these stars exist, these boson stars exist. What would
37:36
Speaker 1: they be like? Could we see the one, would we
37:38
Speaker 1: feel attracted to them? Would they, you know, burn our
37:42
Speaker 1: eyes if we look at them? They would actually look
37:43
Speaker 1: a lot like black holes because they are dense gravitational objects.
37:47
Speaker 1: There contortions in space time right due to the mass
37:51
Speaker 1: of all the axons, And they're not glowing. They're not
37:54
Speaker 1: giving off any light or there's no fusion happening inside
37:58
Speaker 1: of them, but they're not black right. Light can escape them,
38:01
Speaker 1: so there's no event horizon. But they're sort of like transparent.
38:05
Speaker 1: In fact, they're more like transparent holes than black holes.
38:08
Speaker 1: It's weird to think that a whole is transparent, because
38:10
Speaker 1: the aren't all wholes transparent. Technically, I suppose that it
38:15
Speaker 1: would be a non weird hole for once. They would
38:18
Speaker 1: be essentially invisible, but they would distort the light around them,
38:22
Speaker 1: so it's sort of like just being seeing a big
38:24
Speaker 1: lens in the sky. It would look a lot like
38:27
Speaker 1: dark matter, right, dark matter you can't see visually, but
38:30
Speaker 1: you can detect that it's there because of its gravity,
38:33
Speaker 1: and so Boson stars would be the same. They would
38:36
Speaker 1: distort space around them, bending the path of light for example,
38:39
Speaker 1: so you would see gravitational lensing and all sorts of
38:41
Speaker 1: other weird stuff. There wouldn't be an event horizon I see,
38:45
Speaker 1: but wouldn't They wouldn't block or reflect, like like if
38:48
Speaker 1: I have a bunch of axons there and I shoot
38:50
Speaker 1: a laser beam into it. With the laser beam, just
38:52
Speaker 1: shoot right through it. It wouldn't interact with the with
38:55
Speaker 1: the axons. If you shot a laser beam into a
38:57
Speaker 1: Boson star, then no, nothing would happen to go right
39:00
Speaker 1: through because photons and axons don't interact with each other
39:03
Speaker 1: for some theories of axons. There are other versions of
39:06
Speaker 1: axons where the photons and axons can interact a bit.
39:10
Speaker 1: But here we're thinking about axions as dark matter with
39:13
Speaker 1: no reaction to photons. The only effect would be gravitational.
39:16
Speaker 1: If you shot your laser beams sort of near the
39:18
Speaker 1: Boson star, it might curve the path of your laser.
39:22
Speaker 1: It would bend your laser, but the axions and the
39:24
Speaker 1: photons is quantum particles don't interact, I see, and what
39:27
Speaker 1: these things need to be huge? Or could you have
39:30
Speaker 1: a small Bozon star? We don't know. Actually that's a
39:32
Speaker 1: great question. I think they might be really huge. In fact,
39:35
Speaker 1: there's some speculation that some of the black holes at
39:38
Speaker 1: the center of galaxies might actually just be Boson stars.
39:43
Speaker 1: But there's also the possibility that you could make them
39:45
Speaker 1: to be fairly small. In the same way that like
39:47
Speaker 1: black holes you can make to me, really really really small,
39:50
Speaker 1: you could also make Boson stars and it's fairly small
39:53
Speaker 1: helping as long as they were compact enough. All right, Well,
39:56
Speaker 1: so there would be basically transparent. And it's kind of
40:00
Speaker 1: like could they have planets other planets, like real planets
40:03
Speaker 1: orbiting around them? Absolutely they could, and they might also
40:06
Speaker 1: not be transparent for very long because, for example, think
40:10
Speaker 1: about what happens if you toss a banana and a
40:13
Speaker 1: Boson star. What happens, Well, it passes through the axons
40:17
Speaker 1: and it falls towards the center because of the gravity,
40:19
Speaker 1: and then it just sort of stays there right like
40:22
Speaker 1: you just fall into it and not be able to escape.
40:25
Speaker 1: It has the gravitational pull of something else. With the
40:28
Speaker 1: same mass, and so things would fall into the core
40:32
Speaker 1: of it. It would collect normal matter at its core.
40:34
Speaker 1: It wouldn't get crushed or anything. Yeah, absolutely, it might
40:38
Speaker 1: get crushed. Your banana might not survive, but it also
40:41
Speaker 1: wouldn't escape. And so if these boson stars are near
40:44
Speaker 1: other matter, then that matter might fall into them and
40:47
Speaker 1: that would be visible. Oh you mean, like in the
40:49
Speaker 1: same way that dark matter, for example, kind of helps
40:53
Speaker 1: gather galaxy. Yeah, and acon star could help gather banana
40:59
Speaker 1: because the way stars tell us where dark matter is,
41:02
Speaker 1: bananas tell us where both stars are perfect analogy. And
41:07
Speaker 1: that would be super real because you see a banana,
41:09
Speaker 1: but it would have like the mass of a black
41:11
Speaker 1: hole exactly, like the most powerful banana in the universe,
41:15
Speaker 1: and it would attract other bananas and monkeys and r maybe,
41:21
Speaker 1: and you would also get other gravitational effects, like it
41:24
Speaker 1: might have matter swirling around it, the same way that
41:27
Speaker 1: black holes do. If you have nearby gas, it would
41:30
Speaker 1: get pulled in by the gravitational field. But it doesn't
41:32
Speaker 1: always collapse in, right, Not everything near a black hole
41:36
Speaker 1: automatically falls in because it's spinning. So some things instead
41:39
Speaker 1: of falling in gather into this accretion disc, and a
41:43
Speaker 1: Boson star might also get an accretion disk, and it
41:46
Speaker 1: might have radiation from that accretion disc. And the way
41:49
Speaker 1: that we detect black holes normally is we see like
41:53
Speaker 1: gravitational influence and an acretion disc and like signals from
41:57
Speaker 1: that accreation disc of incredible gravity tational stress. Those are
42:01
Speaker 1: also the signals of a Boson star. So how could
42:04
Speaker 1: we tell the difference? Or is it even possible that
42:07
Speaker 1: black holes are made out of bosons? Like you could
42:12
Speaker 1: throw bozons into a black hole and it would grow too, right, Yeah,
42:16
Speaker 1: you can throw anything into a black hole, and you
42:17
Speaker 1: can make a black hole out of anything, So it's
42:19
Speaker 1: possible that black holes have a lot of bosons or
42:22
Speaker 1: axons in them. Certainly, how could you tell the difference
42:25
Speaker 1: between a black hole and a Bozon star. You'd have
42:28
Speaker 1: to look really directly at it, because a Boson star
42:30
Speaker 1: doesn't have an event horizon. So, for example, when we
42:33
Speaker 1: directly image that black hole and we saw the shadow
42:36
Speaker 1: of the black hole, we saw the back of the
42:38
Speaker 1: event horizon in the front of it inside the accretion disk.
42:42
Speaker 1: That's pretty clearly not a Boson star because there's a
42:45
Speaker 1: black spot in the middle. But if you looked at
42:47
Speaker 1: one of these things directly and you didn't see the
42:49
Speaker 1: black spot, if you saw gas all the way through it,
42:51
Speaker 1: then you think, oh, that's probably a Bozon star. All right, Well,
42:54
Speaker 1: then how could we see these hypothetical Bozon stars if
42:57
Speaker 1: they exist? And there are two ways. One is direct
43:00
Speaker 1: imaging of them, right, just look at black hole candidates
43:02
Speaker 1: and see if you can see the event horizon. If
43:05
Speaker 1: you can't, then it might be a Boson star. There's
43:07
Speaker 1: another way, which is maybe easier, because directly imaging black
43:11
Speaker 1: holes is hard. You know, We've been working on it
43:13
Speaker 1: for a long time and only done it for one
43:15
Speaker 1: and that's it. Looking at the gravitational waves. Gravitational waves
43:19
Speaker 1: are generated from spinning black holes or from things moving
43:22
Speaker 1: around black holes, like neutron stars and stuff like that.
43:25
Speaker 1: So because there's a slightly different structure in the field,
43:29
Speaker 1: because boson is of a different distribution than like a singularity,
43:32
Speaker 1: the heart of a black hole is a slightly different
43:34
Speaker 1: pattern in the gravitational waves, so you might be able
43:37
Speaker 1: to detect the difference. There's some recent paper is talking
43:40
Speaker 1: about like exactly how to look for gravitational waves that
43:44
Speaker 1: come from Boson star collisions rather than black hole collisions.
43:48
Speaker 1: So this is an imaginary event featuring two imaginary objects
43:52
Speaker 1: made out of an imaginary particle made out of a
43:54
Speaker 1: lot of imaginary particles. Yes, exactly. I feel like now
44:00
Speaker 1: we're going deeper into the rabbit hole here, we're being
44:02
Speaker 1: incepted to like level four and there's even level five
44:07
Speaker 1: inception there, which is, like, how did these things get
44:09
Speaker 1: made in the first place? Even if axions are real,
44:13
Speaker 1: even if all the laws of physics work the way
44:15
Speaker 1: we're talking about, so that if you put axons in
44:18
Speaker 1: the same place they would make a Boson star. Are
44:20
Speaker 1: their conditions in our universe for that to happen? Should
44:24
Speaker 1: it arise? So it's not easy to imagine how you
44:27
Speaker 1: would make that many axions. Really, you got to go
44:30
Speaker 1: all the way back to the Big Bang and say
44:33
Speaker 1: maybe during the Big Bang there was some crazy fluctuation
44:35
Speaker 1: and these things got made primordially and like before most
44:39
Speaker 1: particles were made, when maybe even early black holes were made,
44:42
Speaker 1: that you've got these weird collections of bosons created quantum
44:46
Speaker 1: mechanically during the Big Bang, and those are the seeds
44:50
Speaker 1: of current Boson stars. Because I guess you can't think
44:53
Speaker 1: of any circumstances right now in our universe in which
44:56
Speaker 1: you could get that many bo's. Yeah, and then maybe Daniel,
45:00
Speaker 1: we're just imaginary imagining these imaginary things. My brain feels
45:04
Speaker 1: like it's filled with banana sometimes, which might be imaginary
45:08
Speaker 1: themselves if they weren't so delicious. Good thing. Physics is
45:12
Speaker 1: so easy, right, all right? Well, so that's a Boson
45:14
Speaker 1: star and that's pretty interesting. And now are there people
45:17
Speaker 1: looking for these right now? Is this something that people
45:20
Speaker 1: are taking seriously or is it still kind of in
45:22
Speaker 1: the back of the conference room. There, It's definitely in
45:24
Speaker 1: the back of the conference room, but there are also
45:27
Speaker 1: some people taking it very seriously, which is sort of
45:29
Speaker 1: the way in physics. You've got like the mainstream stuff
45:32
Speaker 1: people are working on, and then you've got the people
45:34
Speaker 1: thinking in the back of the room, going, m what
45:35
Speaker 1: about this other weird thing? And sometimes those ideas are right.
45:40
Speaker 1: I'm really glad that in science were open to all
45:42
Speaker 1: sorts of crazy ideas. And there are definitely people dedicated
45:46
Speaker 1: to this topic, you know, running detailed simulations of what
45:49
Speaker 1: Boson stars would look like and trying to understand like
45:52
Speaker 1: the plasma loops that might form around them, and how
45:54
Speaker 1: you would see those signals and gravitational wave detectors of
45:57
Speaker 1: the future. So it's definitely something people are thinking about.
46:00
Speaker 1: And how many of those can you fit into a
46:02
Speaker 1: clown car or how many of you are willing to
46:05
Speaker 1: get into one for the sake of physics. That's philosophy.
46:09
Speaker 1: That's philosophy, man, that's not science. See, that's the other
46:12
Speaker 1: imaginary science. Or maybe it's psychology. I don't know. All right, Well,
46:16
Speaker 1: it's always interesting to think about what could be out
46:19
Speaker 1: there in the universe, you know, like we have all
46:21
Speaker 1: these rules, and if you sort of think about those
46:24
Speaker 1: rules enough, you sort of come up with these weird
46:26
Speaker 1: things that may or may not exist. Yeah, And it
46:28
Speaker 1: could be that we are in the era before the
46:30
Speaker 1: discovery of Boson stars, when people are just thinking about
46:33
Speaker 1: what could be out there in the universe. So if
46:36
Speaker 1: you are a budding astronomer or astrophysicist and you're thinking
46:39
Speaker 1: the universe has all been discovered, there is still plenty
46:42
Speaker 1: of crazy stuff out there for you to find. Yeah,
46:45
Speaker 1: because at some point even thinks like black holes in
46:48
Speaker 1: dark matter, they're all imaginary. Back at the conference room,
46:54
Speaker 1: these are now just Nobel prizes waiting to be one. Well,
46:57
Speaker 1: we hope you enjoyed that. And the next time you
47:00
Speaker 1: look at into the Start, I think about what you're
47:01
Speaker 1: not seeing that could be out there sucking bananas and
47:05
Speaker 1: turning them into smoothies. Thanks for joining us, see you
47:09
Speaker 1: next time. Thanks for listening, and remember that Daniel and
47:19
Speaker 1: Jorge explain the Universe is a production of I Heart
47:22
Speaker 1: Radio or more podcast or my heart Radio. Visit the
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47:29
Speaker 1: to your favorite shows. Yeah,