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Are black holes really black holes? · Daniel and Kelly’s Extraordinary Universe

0:01
Speaker 1: Hey, it Jorhan Daniel here, and we want to tell
0:03
Speaker 1: you about our new book. It's called Frequently Asked Questions
0:06
Speaker 1: about the Universe because you have questions about the universe,
0:09
Speaker 1: and so we decided to write a book all about them.
0:12
Speaker 1: We talk about your questions, we give some answers, we
0:14
Speaker 1: make a bunch of silly jokes as usual, and we
0:17
Speaker 1: tackle all kinds of questions, including what happens if I
0:20
Speaker 1: fall into a black hole? Or is there another version
0:22
Speaker 1: of you out there that's right? Like usual, we tackle
0:25
Speaker 1: the deepest, darkest, biggest, craziest questions about this incredible cosmos.
0:29
Speaker 1: If you want to support the podcast, please get the
0:31
Speaker 1: book and get a copy not just for yourself, but
0:34
Speaker 1: you know, for your nieces and nephews, cousins, friends, parents, dogs, hamsters,
0:39
Speaker 1: and for the aliens. So get your copy of Frequently
0:42
Speaker 1: Asked Questions about the Universe is available for pre order now,
0:46
Speaker 1: coming out November two. You can find more details at
0:49
Speaker 1: the book's website, Universe f a Q dot com. Thanks
0:53
Speaker 1: for your support, and if you have a hamster that
0:55
Speaker 1: can read, please let us know. We'd love to have
0:57
Speaker 1: them on the podcast. Hey Daniel, how do you know
1:10
Speaker 1: that an electron is actually an electron? What do you mean?
1:14
Speaker 1: I mean, what else could it be? Well, what do
1:16
Speaker 1: you really know about an electron? Well, that's a good question.
1:19
Speaker 1: I mean, you can measure things about it, like it's mass,
1:22
Speaker 1: and it's charge and it's spin. So even if you can,
1:26
Speaker 1: you know, look at it directly, that's enough to tell
1:29
Speaker 1: you that it's an electron. I guess. So, I mean
1:31
Speaker 1: if it quacks like an electron and it walks like
1:34
Speaker 1: an electron, then you call an electron a doctron. But
1:38
Speaker 1: I guess you know, how do you know there isn't
1:39
Speaker 1: another particle with like the same charge and mass and spin,
1:43
Speaker 1: but is not an electron like another particle hiding and
1:47
Speaker 1: electron clothing. Yeah, like the incocniton or the full electron,
1:53
Speaker 1: or the non electron or the electron. Not. Well, I'm
1:56
Speaker 1: glad we have a name for it, even if we
1:58
Speaker 1: haven't discovered it yet. I am or Hammer cartoonists and
2:16
Speaker 1: the creator of PhD comics. Hi, I'm Daniel. I'm a
2:18
Speaker 1: part of Gold physicist or at least I walk like
2:21
Speaker 1: one and I quack like one. Oh really, physicists quack
2:24
Speaker 1: that a thing you do when you discover something amazing
2:26
Speaker 1: about the universe. Oh yeah, we quack about corks all
2:29
Speaker 1: the time and quasars. Yeah, I guess regular nerds a
2:33
Speaker 1: snort and when they laugh and we're get excited. Physicists
2:37
Speaker 1: are hardcore and you quack, yeah exactly, don't quibble about
2:40
Speaker 1: the way we quack. And that's why you fly south
2:42
Speaker 1: every winter, right, that's why I live in south southern California.
2:46
Speaker 1: Sabbaticals in the South Pacific. No, i' made a mistake.
2:49
Speaker 1: I took my sabbatical by going north. I went to
2:51
Speaker 1: Copenhagen briefly, but you went in the summer though, right,
2:55
Speaker 1: days were long, Right exactly, it's the right place to
2:58
Speaker 1: go in the summer. This is one smart duck. But anyways,
3:01
Speaker 1: welcome to our podcast, Daniel and Jorge Explain the Universe,
3:03
Speaker 1: a production of I Art Radio, in which we fly
3:06
Speaker 1: north and we fly south, we go on sabbatical, and
3:09
Speaker 1: we engage our brains in the big questions of the universe.
3:12
Speaker 1: We try to ask the biggest, deepest, darkest, craziest questions
3:16
Speaker 1: about the nature of the universe, what's in it, what's
3:19
Speaker 1: out there, and what it really means? Is the reality
3:22
Speaker 1: we see around us, the reality that's actually out there
3:25
Speaker 1: independent of human thought, or is it vastly different than
3:28
Speaker 1: our crazy, tiny human brains can't imagine? Is the worldlined
3:31
Speaker 1: us and hiding and pretending to be something that it
3:34
Speaker 1: isn't or is it just the way it looks? Yeah,
3:36
Speaker 1: because it is a pretty tricky universe. You know, it's
3:39
Speaker 1: not only big and almost a hidden from us because
3:42
Speaker 1: it's so large, but there's also, you know, kind of
3:45
Speaker 1: strange things about it, because you know, the only things
3:47
Speaker 1: that we know about the universe are the things we
3:49
Speaker 1: can see or at least measure with our instruments, and sometimes,
3:53
Speaker 1: you know, the universe places tricks on us. Yeah, and
3:55
Speaker 1: you can ask really fun, interesting philosophical questions, like how
3:58
Speaker 1: do you know what some thing is? Like you eat
4:00
Speaker 1: an ice cream cone? You know, it feels like an
4:02
Speaker 1: ice cream cone in your hand, it tastes like an
4:04
Speaker 1: ice cream cone. How do you know it's not actually
4:06
Speaker 1: something else and you're being fooled and it tastes like
4:09
Speaker 1: an ice cream cone, but it's actually something crazy and weird,
4:12
Speaker 1: like an assembly of nanobots that's been collected to like
4:15
Speaker 1: invade your body and taste like ice cream. Oh, my gosh,
4:19
Speaker 1: you just give me nightmares about eating ice cream. I
4:23
Speaker 1: hope I didn't just ruin ice cream for everybody you
4:25
Speaker 1: might have. Yeah, No, I'm gonna worry eating nanobots or
4:28
Speaker 1: something evil nanobots fooling my tongue. There is a deep
4:31
Speaker 1: question there because we are limited in the ways that
4:33
Speaker 1: we interact with the universe, right, We can't see the absolute, ultimate,
4:37
Speaker 1: complete truth of the universe. Ever. We have these narrow
4:39
Speaker 1: little ways. We can see, we can taste, we can touch,
4:42
Speaker 1: we can smell, and that paints a picture in our
4:45
Speaker 1: minds of what we think the universe is like. But
4:48
Speaker 1: it's a very narrow way to interact with the universe,
4:50
Speaker 1: and it is possible that we are confused about what's
4:53
Speaker 1: actually out there. Yeah, because I guess the universe is
4:56
Speaker 1: tricky like that, And I mean it's so complex. That's
4:59
Speaker 1: something that it seem like, you know, ice cream could
5:02
Speaker 1: be something else. You know, it could have fake sugar
5:04
Speaker 1: or nana bots or artificial flavors, you know, or artificial
5:09
Speaker 1: nana bouts, Like, hey, I ordered nano bots of my
5:11
Speaker 1: ice cream. These aren't real nano bots. Now, I can't
5:13
Speaker 1: even trust the nana bouts They could be you know,
5:16
Speaker 1: the cheap kind or something. That's right, they kind of
5:18
Speaker 1: give you indigestion later, you don't want to eat those.
5:20
Speaker 1: It could be po bots or fempty bots. Well, I
5:23
Speaker 1: paid for Nana bots and I just got these Milli bots. Man,
5:25
Speaker 1: I can even see these with my eyeballs. What's going on?
5:28
Speaker 1: They're too crunchy. Yeah, they ruined the texture of your
5:32
Speaker 1: fake ice cream. But mostly we're not that worried about
5:34
Speaker 1: ice cream. As long as it tastes good, it's fine.
5:37
Speaker 1: Mostly we're worried about the nature of the universe and
5:40
Speaker 1: what's in it, what's out there in the universe. Yeah,
5:42
Speaker 1: and one of the most interesting things out there for
5:45
Speaker 1: people to study are black holes. It seems like we
5:48
Speaker 1: get a question about black holes almost every week on
5:51
Speaker 1: the podcast, right, Yeah, this should basically become a black
5:53
Speaker 1: hole podcast. We're basically just falling into the gravitational attraction
5:57
Speaker 1: of the mysteries of black holes. Yeah. I guess the
5:59
Speaker 1: r very attractive and deep. Yeah, and once you start
6:03
Speaker 1: talking about them, you basically can't escape. There's like a
6:05
Speaker 1: question horizon or something. Yeah, it's a massive topic. But
6:10
Speaker 1: even black holes, as you know, as much as we
6:13
Speaker 1: know about them, Like, we know they're there. You can
6:15
Speaker 1: see them gravitationally. And now recently, in the last year
6:18
Speaker 1: or two, we've actually gotten pictures of black holes. Right, Yeah,
6:21
Speaker 1: we have a lot of information about black holes, and
6:23
Speaker 1: you just said we know that they are there, And
6:26
Speaker 1: that's a really interesting question. Like, we know a lot
6:29
Speaker 1: of things about black holes. We've measured a lot of
6:31
Speaker 1: things about black holes. A lot of things that we
6:33
Speaker 1: see makes sense a black holes were there. But you know,
6:36
Speaker 1: how do we really know it's not just a bunch
6:39
Speaker 1: of nanobots out there fooling us in deep space? Oh? Man,
6:42
Speaker 1: I imagine we're not going to be licking the black
6:44
Speaker 1: holes or eating them, hopefully not. I don't think anybody
6:47
Speaker 1: ever said licking the black hole until you just said it.
6:50
Speaker 1: Then it's the first time in human history anybody ever
6:52
Speaker 1: said that. We'll trade that and put it on our
6:54
Speaker 1: T shirts. Daniel and Horror explain the universe liking the
6:58
Speaker 1: black holes. That's like a pitch for the science fiction
7:01
Speaker 1: version of a Christmas story. Yeah, you're going to shoot
7:05
Speaker 1: your eye out and or well into a singularity forever. Alright,
7:09
Speaker 1: we're talking about black holes today and this sort of
7:12
Speaker 1: philosophical question almost about the true nature of black holes
7:16
Speaker 1: and whether or not we are actually looking at or
7:18
Speaker 1: feeling black holes. Yeah, what's actually out there that's giving
7:22
Speaker 1: us the impression that black holes exist? And could it
7:25
Speaker 1: be something else masquerading as a black hole? Oh man, sneaky.
7:30
Speaker 1: So today on the program, we'll be tackling the question
7:37
Speaker 1: what if black holes are not actually black holes? And Daniel,
7:42
Speaker 1: are we questioning you know that they're not actually black
7:45
Speaker 1: the color black, or that they're not actually holes or
7:48
Speaker 1: both both and everything? We're questioning everything today, we're blowing
7:52
Speaker 1: it all up. No, we are wondering what we actually
7:55
Speaker 1: know about the nature of black holes. What evidence do
7:57
Speaker 1: we have that they are this we your conceptual object
8:01
Speaker 1: that really just exists in our minds and existed only
8:04
Speaker 1: in the minds of physicists for fifty years before we
8:07
Speaker 1: discovered them. Well, actually, I guess maybe they existed in
8:10
Speaker 1: the universe before that, but the idea is only fifty
8:12
Speaker 1: or so years old, and so we're asking the question,
8:14
Speaker 1: is what's actually out there consistent with what's in our mind? Yeah,
8:18
Speaker 1: Because I think black holes have had sort of an
8:20
Speaker 1: interesting journey, right, Like first week thought up of them
8:24
Speaker 1: as an imaginary thing, like we saw the theory and
8:26
Speaker 1: we imagine that they could exist, and then we sort
8:28
Speaker 1: of confirmed that they're there but not actually seeing them.
8:32
Speaker 1: They sort of looked like they were there gravitationally, and
8:36
Speaker 1: then more recently we've actually seen them. We have pictures
8:39
Speaker 1: of them. But now we're asking the question here today,
8:42
Speaker 1: are they really actually black holes? The things that we're
8:45
Speaker 1: seeing in feeling? Yeah, because can you really see something
8:48
Speaker 1: that's just black? You know, it's like sort of not
8:50
Speaker 1: seeing it is seeing it. You know, we didn't see
8:53
Speaker 1: light from the black hole, which would have told us
8:56
Speaker 1: it's not a black hole. What we saw is not light,
8:59
Speaker 1: which is not the same thing is seeing the black hole.
9:01
Speaker 1: We didn't see the not black hole, or we saw
9:05
Speaker 1: the not black hole we didn't. I don't know. I'm
9:07
Speaker 1: confusing myself. Did it not see a not black hole
9:10
Speaker 1: that is not actually there? Let's just keep going in
9:13
Speaker 1: exactly consistent with the black hole prediction. We didn't see
9:16
Speaker 1: photons from it. What does that actually proved? Right? Right?
9:20
Speaker 1: If it looks like a triple negative and it walks
9:22
Speaker 1: like a triple negative, it's actually true. Maybe I don't
9:25
Speaker 1: know these philosophical jokes are too much for me. But
9:28
Speaker 1: I guess if a black hole is not actually a
9:29
Speaker 1: black hole, what else could it be? Yeah, and so
9:32
Speaker 1: there are a bunch of other ideas for what could
9:36
Speaker 1: maybe be masquerading as a black hole. What out there
9:39
Speaker 1: in the universe, other theoretical concepts for what could give
9:42
Speaker 1: us the same sort of set of observed data that
9:45
Speaker 1: could give us the same experience without actually being a
9:48
Speaker 1: black hole. Interesting? Do we have a name for these
9:50
Speaker 1: mysterious fake full black holes or black holes? We do?
9:55
Speaker 1: And this is this call these things dark stars, which
9:59
Speaker 1: is how sort of cool in science fiction? E. It
10:01
Speaker 1: does sound like another Marvel superhero or villain. I think,
10:05
Speaker 1: actually that is maybe a d C hero, thinking we'll
10:08
Speaker 1: have to google it. It sounds to me like the
10:10
Speaker 1: jet black version of the Death Star. Interesting, that's for
10:14
Speaker 1: the next Star Wars equal when there's another death Star
10:17
Speaker 1: like the fourth one, but actually bigger and darker. Is
10:20
Speaker 1: that what you're saying? Yeah, well, you know in Star
10:22
Speaker 1: Wars they're always saying that's not a moon, that's a
10:24
Speaker 1: space station, and this one they'll say, that's not a
10:27
Speaker 1: black hole, that's a dark star space station. Oh my,
10:30
Speaker 1: gosh called j J Abams. I'm sure he's a listener,
10:34
Speaker 1: So j J you call us, that's right, you have
10:38
Speaker 1: Daniel's email for waiting. So a dark star. So that's
10:42
Speaker 1: kind of what we'll be talking about today, is that,
10:44
Speaker 1: you know, maybe black holes are not black holes. Maybe
10:46
Speaker 1: there's something called a dark stars. Yeah, exactly. These are fun,
10:50
Speaker 1: crazy concepts that might be real out there in the universe.
10:53
Speaker 1: So as usual, we were wondering how many people out
10:56
Speaker 1: there had thought about the trueness of black holes and
10:59
Speaker 1: had heard of these things called dark stars. So Daniel
11:03
Speaker 1: went out there and ask people on the internet what
11:06
Speaker 1: is a dark star? And if you are out there
11:08
Speaker 1: in the Internet and still don't feel safe venturing outside
11:11
Speaker 1: and talking to humans in person, I get it. And
11:14
Speaker 1: so if you'd like to participate in these questions online
11:17
Speaker 1: please they'll be shy and right to us two questions
11:19
Speaker 1: at Daniel and Jorge dot com. We'd love to hear
11:22
Speaker 1: your voice on the podcast. So think about it for
11:25
Speaker 1: a second. If I say the words dark star, what
11:27
Speaker 1: comes to your mind? It was what people had to say.
11:30
Speaker 1: I think a dark star is a white dwarf that
11:34
Speaker 1: has sufficiently cooled to become a black dwarf and doesn't
11:40
Speaker 1: emit any radiation. Sounds like it's one that would not
11:44
Speaker 1: emit any light, but maybe it's still emits radiation. Why
11:49
Speaker 1: that would be, I have no idea, but that's my guess.
11:52
Speaker 1: So I think I've heard of this where like say
11:56
Speaker 1: a brown dwarf, a brown dwarf is niclear a star,
12:00
Speaker 1: but it's a lot gammer and a lot cooler, and
12:05
Speaker 1: typically a lot smaller. So that would be what I
12:09
Speaker 1: would think a dark star is. White dwarfs are going
12:13
Speaker 1: to burn out and become dark. It could also be
12:16
Speaker 1: you guys thinking about dark matter somehow forming a star,
12:20
Speaker 1: but the dark matter cannot interact with itself, so does
12:24
Speaker 1: that work. At the beginning, I thought this dark star
12:28
Speaker 1: was black hole, but lately I read that dark star
12:36
Speaker 1: might be a type of star from the beginning of
12:38
Speaker 1: the universe, really really big star, much bigger than battle
12:45
Speaker 1: Juice or any other type of star that we've seen
12:49
Speaker 1: until now. So this is from the really beginning of
12:56
Speaker 1: the universe. If I say to you, what is the
12:58
Speaker 1: dark star, what would you think? Well? Probably it could
13:02
Speaker 1: also me and not very bright stars, and mostly there
13:05
Speaker 1: are rampwarfs like Barnold Star are proxima centauri. All those
13:11
Speaker 1: dark not very dark, does not be bright. A dark
13:16
Speaker 1: star also awesome name for a band or opening cover
13:19
Speaker 1: of a band. Dark star definitely, I'm going to go
13:23
Speaker 1: with the dark matter star, even though dude, I have
13:25
Speaker 1: no idea how such a thing could exists, because what
13:27
Speaker 1: even is dark matter? No one knows. But if it
13:30
Speaker 1: could clump and immage energy in the form of dark radiation, well,
13:34
Speaker 1: even better band name. Then you will get a dark star.
13:37
Speaker 1: I think a dark star is probably maybe a theoretical
13:42
Speaker 1: object in dark matter, So maybe it's a star made
13:44
Speaker 1: entirely of dark matter, but I'm not arrely sure. I
13:47
Speaker 1: guess a dark star would be the star that's not
13:50
Speaker 1: emitting light, so maybe a star that has already undergone
13:57
Speaker 1: a supernova or that has collapsed into a black hole
14:02
Speaker 1: or something otherwise. Um, I guess a rock star that
14:08
Speaker 1: trash is hotel rooms would also be a dark star. Right.
14:13
Speaker 1: Interesting answers here. I feel like all of these answers
14:15
Speaker 1: could be a theory of physics in itself. There are
14:19
Speaker 1: some great answers, and you hear some real knowledge in there.
14:22
Speaker 1: There are people talking about dark matter stars or black dwarves.
14:25
Speaker 1: Black dwarves are a real thing, are they? They absolutely are.
14:28
Speaker 1: There are when a white dwarf, which is just a
14:31
Speaker 1: huge hunk of hot metal no longer actually fusing and
14:34
Speaker 1: giving off light, just sort of like glowing in the universe,
14:37
Speaker 1: when they cool down eventually and stop glowing and become dark,
14:41
Speaker 1: and so that's a black dwarf. I like this suggestion
14:43
Speaker 1: that maybe it's like a dark matter star, which we
14:46
Speaker 1: actually talked about on the podcast, right, Yeah, we did
14:48
Speaker 1: talk about whether you can make dark matter stars and
14:50
Speaker 1: maybe whether they would make dark photons using dark fusion
14:53
Speaker 1: or something crazy like that. So if you're interested in
14:56
Speaker 1: dark matter stars, go check out that whole episode. I see,
14:58
Speaker 1: but that's its separate rock band, right, There's a Dark
15:01
Speaker 1: Star and there's Dark Matter Star. Yeah. I think they
15:04
Speaker 1: toured together once in the eighties, but it didn't go
15:06
Speaker 1: very well. The Extra Dark Tour is epic and the
15:09
Speaker 1: story well, they never turned on the lights and so
15:11
Speaker 1: nobody could tell if they were there. Yeah, they all right,
15:15
Speaker 1: And then someone at the end said that maybe it's
15:17
Speaker 1: a black hole. So they were sort of close to
15:20
Speaker 1: the truth here, maybe yeah, yeah, maybe there are masquerining
15:23
Speaker 1: as black holes. All right, let's jump into this subject
15:26
Speaker 1: of whether or not a black hole is actually a
15:28
Speaker 1: black hole and what else it could be. So let's
15:32
Speaker 1: start from the basics. Daniel, why do we think we've
15:35
Speaker 1: seen black holes? It's a really fun story. Actually, we
15:38
Speaker 1: did a podcast episode about the discovery of black holes,
15:41
Speaker 1: and it's really cool to trace the history of the
15:44
Speaker 1: idea and then the history of the observation, like, this
15:48
Speaker 1: is not something I think we could have ever discovered
15:51
Speaker 1: if we didn't know to look for it, because in
15:53
Speaker 1: the end, the evidence is not a smoking gun. It's
15:56
Speaker 1: like the kind of thing you can hunt for subtle
15:58
Speaker 1: signals of if you know to see it. So it's
16:01
Speaker 1: sort of like, you know, a story. The moral of
16:03
Speaker 1: the story is you should really think carefully about what's
16:06
Speaker 1: out there in the universe, because it might give you
16:07
Speaker 1: crazy ideas for what to look for. And this crazy
16:10
Speaker 1: idea came from Albert Einstein himself in nineteen fifteen when
16:14
Speaker 1: he came up with general relativity, which is the way
16:17
Speaker 1: to describe how space bends in response to mass, and
16:20
Speaker 1: then how mass moves through that bend space. So that's
16:23
Speaker 1: the theory of general relativity, and just a year later
16:26
Speaker 1: somebody solved his equations and discovered they predicted something really,
16:29
Speaker 1: really weird. And that's when the idea of a black
16:31
Speaker 1: hole was born. Now more than a hundred years ago, right,
16:34
Speaker 1: maybe you can step us through this a little bit.
16:36
Speaker 1: So what was Einstein looking at? Like, he was looking
16:39
Speaker 1: at the equations of gravity, and like, what happens if
16:42
Speaker 1: you get enough gravity into into or mass into one
16:44
Speaker 1: tiny spot? How does that affect the equations that he
16:47
Speaker 1: was coming up with? What exactly was he looking at?
16:49
Speaker 1: He was looking for a general equation, one that described,
16:53
Speaker 1: you know how space bends when you have mass in it.
16:55
Speaker 1: So if you put a son here and you put
16:57
Speaker 1: a planet there, then how does space curve? And then
17:00
Speaker 1: how do things move through that curved space? But his
17:03
Speaker 1: equations are famously hard to solve, Like, we can't solve
17:06
Speaker 1: them for even very basic simple scenarios like a son
17:09
Speaker 1: and a planet. We've only been able to solve them
17:11
Speaker 1: for very simple situations like an empty universe with nothing
17:15
Speaker 1: in it, or a universe like filled smoothly with matter
17:19
Speaker 1: with no lumps or bumps at all. These kinds of
17:22
Speaker 1: very simple situations lead to solutions where we say, if
17:25
Speaker 1: you have a certain mass distribution, then I can tell
17:27
Speaker 1: you how space bends. It's not easy for a given
17:31
Speaker 1: arbitrary mass distribution to solve Einstein's equations and know how
17:34
Speaker 1: space bends. It's like, it's very difficult. Einstein's equations just
17:38
Speaker 1: tell you, like the rules that it has to follow.
17:40
Speaker 1: But as we talked about once in the podcast, knowing
17:42
Speaker 1: the equations doesn't necessarily mean you know how to find
17:45
Speaker 1: a solution. And so even though we had these equations,
17:47
Speaker 1: nobody had ever solved his equations, including Einstein. When he
17:50
Speaker 1: put them out there, he was like, here are the equations.
17:53
Speaker 1: But just a year later, a soldier on the front
17:55
Speaker 1: lines of World War one, kurse short child, solve them
17:59
Speaker 1: for this easy scenario where you have a really immense
18:02
Speaker 1: amount of mass all in one place. And so that
18:04
Speaker 1: was the first ever solution to the Einstein equations. This
18:07
Speaker 1: one really weird, extreme scenario. And sometimes in math, like
18:11
Speaker 1: the really extreme weird scenarios are easier to solve than
18:14
Speaker 1: the more complicated general ones. I see. So Einstein didn't
18:18
Speaker 1: even think about black holes. He just put out, you know,
18:21
Speaker 1: general equations for like everyday life and somebody looked at
18:24
Speaker 1: that and say, well, what if I crank up the
18:26
Speaker 1: mass and put it onto one spot that leads to
18:29
Speaker 1: like a special solution, which is a black hole. Precisely
18:32
Speaker 1: in Einstein was like, wow, nice work and never thought
18:35
Speaker 1: of that. That's very cool. He was like man penning
18:37
Speaker 1: himself on the back, kind of like, wow, that's a
18:40
Speaker 1: pretty awesome thing that came from something I did. Yeah,
18:43
Speaker 1: I think it's always cool in science to see somebody
18:45
Speaker 1: follow up on your work. You know, you don't want
18:46
Speaker 1: to write a paper and then have nobody read it
18:48
Speaker 1: and nobody respond to it. You want people to read
18:50
Speaker 1: it and build on it. And of course lots of
18:52
Speaker 1: people have done that for now, but this was like
18:54
Speaker 1: the first step. This is the first time somebody took
18:56
Speaker 1: his equations and said, all right, you know what kind
18:59
Speaker 1: of universe is him this describe So Einstein hadn't really
19:02
Speaker 1: thought about this idea of like a volume in space
19:05
Speaker 1: that if you go into it you can never escape. No,
19:07
Speaker 1: he had not thought about that at all. And in fact,
19:09
Speaker 1: even though this solution existed in general relativity since the
19:14
Speaker 1: nineteen sixteen, people didn't really understand the impact of the concept.
19:18
Speaker 1: What it meant, you know, what it would actually look
19:20
Speaker 1: like in space until decades later. It was like in
19:23
Speaker 1: the fifties that this concept of an event horizon was
19:27
Speaker 1: even invented. You know, before that people were like, well,
19:29
Speaker 1: what would that mean? Would it just looks like sort
19:31
Speaker 1: of a frozen star because there's so much gravity to
19:34
Speaker 1: be crazy time dilation. So it wasn't until the fifties
19:37
Speaker 1: of people realized that no information could leak out of this,
19:39
Speaker 1: that there was like a barrier beyond which all information
19:42
Speaker 1: was hidden. So it takes decades sometimes to understand the
19:45
Speaker 1: consequences even of theoretical ideas interesting. So I guess the
19:49
Speaker 1: black hole wasn't really a black hole for for forty
19:52
Speaker 1: years until somebody figured out that, you know, if you
19:55
Speaker 1: actually were in the presence of one, it would look
19:57
Speaker 1: like a giant black ball. Yeah, but even then it
20:00
Speaker 1: was like a crazy idea. And you have to understand,
20:02
Speaker 1: physics is filled with crazy hypothetical ideas that nobody believes
20:06
Speaker 1: are real, that nobody thinks actually exist in our universe.
20:09
Speaker 1: Like if you read papers, there are papers describing all
20:12
Speaker 1: sorts of crazy, bonkers things, and these are just theorists exploring,
20:15
Speaker 1: like what could happen. What about this, could this work?
20:18
Speaker 1: What would it mean? And this was in that category
20:20
Speaker 1: for a long long time, not something anybody ever expected
20:23
Speaker 1: to see in the universe or actually observe. And that
20:26
Speaker 1: changed in the sixties when there was the discovery of
20:29
Speaker 1: neutron stars. I made a podcast recently about the discovery
20:32
Speaker 1: of pulsars, which was very cool. That shocked people because
20:35
Speaker 1: these are closely related to black holes. They're very dense,
20:38
Speaker 1: very compact objects with incredible gravity. So people start to think,
20:41
Speaker 1: hold on a second, if neutron stars are real, could
20:44
Speaker 1: black holes be real? Also, so neutron stars are totally
20:47
Speaker 1: different because you can still escape a neutron star, right, Yeah,
20:50
Speaker 1: they don't have an event horizon, but they are crazy
20:53
Speaker 1: dense gravitational objects. Okay, so we found it, and that
20:56
Speaker 1: made people think, Hey, maybe this other crazy idea called
20:59
Speaker 1: the black all exists out there. Let's go look for it. Yeah.
21:02
Speaker 1: And then around the same time, we started seeing unexplained
21:05
Speaker 1: radiation from the sky, like people were sending rockets up
21:09
Speaker 1: into the upper atmosphere to measure the radiation from space,
21:12
Speaker 1: and they found an incredibly bright X ray source that
21:15
Speaker 1: nobody could explain, like something out there was generating very
21:19
Speaker 1: very high energy photons. To have high energy photons, you
21:22
Speaker 1: need like really really hot gas, and you know, you
21:25
Speaker 1: look in the sky and you don't see anything there,
21:28
Speaker 1: so you're like, what's out there? It's dark and it's
21:30
Speaker 1: generating this crazy X ray source. So that was weird
21:33
Speaker 1: and interesting. Well, I mean it's dark and like the
21:36
Speaker 1: visible light spectrum, is that what you mean? Right, Like
21:39
Speaker 1: you can't see with the naked eye, but if you
21:40
Speaker 1: have an X ray telescope you can see the light
21:42
Speaker 1: in that frequency. Yeah, And so that tells you there's
21:44
Speaker 1: something out there which is glowing only in this very
21:47
Speaker 1: very high energy photons. That's weird, you know, And so
21:51
Speaker 1: we knew it was something and it had to be
21:52
Speaker 1: kind of small because it was like not a whole
21:54
Speaker 1: lot of room around there. You could like pinpoint where
21:57
Speaker 1: this was coming from, and it couldn't be some like huge,
22:00
Speaker 1: massive extended object because there was like other stuff nearby.
22:03
Speaker 1: And that was the sort of the second clue, like
22:05
Speaker 1: we saw that there was something out there that was
22:06
Speaker 1: dark because we couldn't see it in a visible light,
22:09
Speaker 1: but it was generating these X rays and it was
22:11
Speaker 1: pretty small. We found another example of one that was
22:15
Speaker 1: orbiting a super giant blue star and it was emitting
22:19
Speaker 1: this crazy radiation, but there was nothing visible there and
22:22
Speaker 1: there wasn't a lot of room for anything, So that
22:25
Speaker 1: suggested it had to be something which was like very
22:27
Speaker 1: small but very high energy. Did you call them like
22:30
Speaker 1: X stars or x essence? There were so small, extra small,
22:36
Speaker 1: all right, So then people went out to look for
22:38
Speaker 1: black holes. But I guess the question is was what
22:40
Speaker 1: they found actually black holes? So let's get into that
22:44
Speaker 1: question and what this dark star is and what it means.
22:48
Speaker 1: But first let's take a quick break, all right. I
23:03
Speaker 1: know we are questioning black holes. Are black holes actually
23:07
Speaker 1: black holes, like in the sense of the concept of
23:10
Speaker 1: a black hole that Einstein helped figure out, or maybe
23:13
Speaker 1: there could be something else that acts like something that
23:15
Speaker 1: could be a black hole. Yeah. I feel like we're
23:17
Speaker 1: in you know, act two of some murder mystery where
23:20
Speaker 1: we have a bunch of clues and we have a suspect,
23:22
Speaker 1: and we're like, all these clues pointed that suspect, and
23:25
Speaker 1: then we're wondering, hole on a second, is it possible
23:28
Speaker 1: that it was actually the ex husband or the sun
23:31
Speaker 1: or whatever, were that one character that you didn't pay
23:33
Speaker 1: attention to, and you have to reassess your evidence. You're like,
23:36
Speaker 1: what do we actually know about who killed this person?
23:39
Speaker 1: So this is the part where you like twiddle your
23:42
Speaker 1: mustache and like what if, Yeah, you know, maybe that
23:46
Speaker 1: was just a paste on mustache or maybe there's shaved
23:49
Speaker 1: their mustache off or something. You know, the whole thing
23:51
Speaker 1: was just a deep fick. And so I think it's
23:53
Speaker 1: useful to like catalog exactly what we do know about
23:56
Speaker 1: these objects that we've been calling black holes. But maybe
23:59
Speaker 1: it's really just the ex husband or an ex black
24:02
Speaker 1: hole husband. Anyways, So you're telling me that we sort
24:06
Speaker 1: of figured out theoretically that there could be black holes
24:09
Speaker 1: out there, and then we saw some clues and then
24:12
Speaker 1: we actually went and found what we think are black holes. Yeah,
24:15
Speaker 1: we have identified these objects out there in space, and
24:18
Speaker 1: essentially we know that they are small, that they are dark,
24:22
Speaker 1: and that they are heavy. Right. We know they're small
24:25
Speaker 1: because sometimes we see other stars orbiting nearby them and
24:28
Speaker 1: coming very very close, so they can't be that big.
24:30
Speaker 1: We know that they are dark because they don't give
24:32
Speaker 1: off a lot of visible radiation or almost none or
24:34
Speaker 1: exactly none, and We know that they are heavy because
24:37
Speaker 1: we can measure their gravitational impact on other stars nearby.
24:41
Speaker 1: We see stars like whizzing around them really fast, which
24:44
Speaker 1: only happens you have like a lot of gravity. So
24:47
Speaker 1: we have something that's small and dark and heavy. And
24:51
Speaker 1: for a long time we had, you know, only one
24:53
Speaker 1: candidate that could fit the bill, one candidate that could
24:56
Speaker 1: satisfy all of those requirements, and that was black holes.
25:00
Speaker 1: So I guess, yeah, I guess from a far enough distance,
25:02
Speaker 1: that's how you would define it, right, if you're far
25:04
Speaker 1: away enough, it's just something that is not visible in
25:09
Speaker 1: the in the light invisible light spectrum. But it's also
25:12
Speaker 1: very heavy, yeah, because we've never like actually seen an
25:15
Speaker 1: event horizon in the sense that we haven't like dropped
25:18
Speaker 1: something in it and see it disappear, you know, or
25:21
Speaker 1: measure the gravitational impact on it. Even the direct photograph
25:24
Speaker 1: we have of a black hole, right, the one that
25:27
Speaker 1: was a big hullabaloo in the news and etcetera, Like,
25:29
Speaker 1: what is it? Really what you're looking at is an
25:31
Speaker 1: accretion disc is the gas around the black hole, and
25:34
Speaker 1: in the center you see something black. So again you
25:37
Speaker 1: know that it's small, that it's dark and it's heavy,
25:40
Speaker 1: you don't actually know it's nature. And the argument that
25:44
Speaker 1: it's a black hole is basically like nothing else can
25:46
Speaker 1: do that. So if you can think of something else
25:49
Speaker 1: that can do that, then you know, maybe it's that
25:51
Speaker 1: other thing instead. But we've also seen gravitational waves right
25:55
Speaker 1: from black holes or what we think are black holes
25:57
Speaker 1: crashing into each other. We have exactly we've seen gravitational
26:00
Speaker 1: waves from black holes merging from neutron stars merging from
26:04
Speaker 1: neutron stars, and black holes merging. What does that tell us?
26:07
Speaker 1: It tells us again that there's something very massive with
26:10
Speaker 1: a lot of gravity and that general relativity mostly works,
26:14
Speaker 1: So that could be explained by something else, you know,
26:17
Speaker 1: just as massive and small and dark in that same
26:20
Speaker 1: location that would also emit gravitational waves, like anything that
26:25
Speaker 1: dense and small would emit gravitational waves also, So that's
26:29
Speaker 1: also not a unique signature of black holes. Like let's
26:32
Speaker 1: not jump to conclusions. And so maybe a possible thing
26:35
Speaker 1: this could be instead of a black hole is something
26:38
Speaker 1: called a dark star, So like what is the dark star? Then? Yeah,
26:41
Speaker 1: So the idea is, you know, exercise your brain, think
26:44
Speaker 1: about other ways to arrange matter that gives the same
26:47
Speaker 1: sort of outwards appearance but looks different fundamentally. And so
26:50
Speaker 1: a dark star is like again very very dense matter.
26:54
Speaker 1: You know, you take star and it's done burning, and
26:57
Speaker 1: so it no longer can provide like ready Asian pressure
27:00
Speaker 1: to push outwards, and gravity takes over and it pulls
27:04
Speaker 1: the star in and it collapses into something very very dense.
27:07
Speaker 1: And there's lots of different scenarios. One scenarios it becomes
27:10
Speaker 1: a neutron star, right, and that's a scenario where to
27:12
Speaker 1: avoids total gravitational collapse because of the neutrons putting pressure
27:16
Speaker 1: on each other. But there's this other idea that it
27:19
Speaker 1: could collapse to something even more dense than a neutron star,
27:22
Speaker 1: but not a black hole. And so that's what a
27:24
Speaker 1: dark star is. It's got something called a plank core
27:28
Speaker 1: where the core is collapsed and gravitationally, but it doesn't
27:30
Speaker 1: go all the way to a black hole because something
27:32
Speaker 1: prevents that, something does actually push back. Interesting, Yeah, I
27:36
Speaker 1: remember a neutron star. It's like the stuff is squeezed
27:39
Speaker 1: together so much that it like dissolves into almost pure corks. Right,
27:43
Speaker 1: And so you have this giant wall of corks kind
27:46
Speaker 1: of holding together because there's enough energy there to pushing
27:50
Speaker 1: the quarts pushing each other away, but it's still super
27:53
Speaker 1: super dense. Yeah, and we do not understand the internal
27:55
Speaker 1: physics of the neutron star very well at all. It's
27:58
Speaker 1: like a really active area of research, and it's really
28:01
Speaker 1: difficult to study because corks are complicated. You know, they
28:04
Speaker 1: used the strong force, which is a big mess to
28:06
Speaker 1: do calculations in. Every time you emit a gluon, it
28:08
Speaker 1: emits more gluons. You have infinite numbers of gluons every
28:11
Speaker 1: time you want to do a calculation. So we don't
28:13
Speaker 1: really understand what's going on inside a neutron star. But roughly, yes,
28:16
Speaker 1: it's like a huge particle because all the corks are
28:19
Speaker 1: bound together into this incredible you know, like ten fifteen
28:23
Speaker 1: kilometer objects that's the mass of the Sun. So you're
28:26
Speaker 1: saying that there's another step that you can take between
28:28
Speaker 1: that and a black hole, which is maybe a dark star.
28:32
Speaker 1: And so what's happening, Like are the corks somehow running
28:35
Speaker 1: out of juice and so they squeeze in a little further,
28:38
Speaker 1: Like what's going on? How would this dark star come
28:40
Speaker 1: to be yes. So the reason neutron star is stable
28:42
Speaker 1: is because the corks are pushing back against each other.
28:45
Speaker 1: And so to go deeper and darker and go beyond
28:49
Speaker 1: a neutron star, you need more gravity. So if you
28:51
Speaker 1: have more mass than a neutron star can be, like
28:54
Speaker 1: neutron stars can be at most, you know, mass, maybe
28:57
Speaker 1: twice the mass of the Sun or so, we're not
28:59
Speaker 1: exactly sure. If you have more mass than that, then
29:02
Speaker 1: you can have enough gravity to overcome whether corks are
29:05
Speaker 1: doing to resist the collapse, just the same way like
29:07
Speaker 1: our son currently is resisting gravitational collapse. It's doing so
29:11
Speaker 1: by burning and his fusion and photons pushing out. The
29:14
Speaker 1: neutron stars pushing out because of the cork forces. If
29:17
Speaker 1: you have more gravity, you can overcome that, and then
29:19
Speaker 1: you can go deeper. And there's another layer. People think
29:22
Speaker 1: this is all hypothetical. People think that there's another layer
29:25
Speaker 1: where quantum mechanics itself prevents you from getting to a
29:28
Speaker 1: black hole. So the particles get so close that the
29:31
Speaker 1: quantum mechanics uncertainty principle prevents you from collapsing even further. Interesting,
29:36
Speaker 1: so I would have like a neutron star super dance,
29:39
Speaker 1: and I add more neutrons to it, more mass to it,
29:43
Speaker 1: and before it actually collapses into a black hole, maybe
29:47
Speaker 1: there's something about quantum mechanics that keeps it not collapsing,
29:52
Speaker 1: because quantum mechanics doesn't like having particles localized in a
29:55
Speaker 1: very specific region. Right, The whole idea of a singularity
29:59
Speaker 1: inside a black whole huge amount of mass and basically
30:02
Speaker 1: zero volume, is nonsensical when it comes to quantum mechanics.
30:05
Speaker 1: Quantum mechanics says, if that happens, then the uncertainty and
30:08
Speaker 1: the momentum of all those particles would basically be infinite,
30:11
Speaker 1: so they would basically have infinite energy, and then they
30:13
Speaker 1: would escape. The whole thing of a singularity doesn't make
30:16
Speaker 1: sense from the point of view of quantum mechanics. So
30:18
Speaker 1: the idea is maybe quantum mechanics prevents you from getting there,
30:21
Speaker 1: that as the particles are collapsing, that the uncertainty principle
30:25
Speaker 1: prevents them from getting so close as to actually form
30:28
Speaker 1: a singularity. I guess the key thing here is that
30:30
Speaker 1: it's small, it's dark, it's super dense, but it's not
30:33
Speaker 1: technically a black hole because it doesn't get dense enough
30:37
Speaker 1: to form an event horizon, which is like the actual
30:40
Speaker 1: like point where nothing can escape. Yeah, this dark star
30:43
Speaker 1: would not have an event horizon exactly. And also it
30:45
Speaker 1: wouldn't have a singularity at its core. You know, the
30:48
Speaker 1: really defining characteristics of a black hole are the singularity
30:51
Speaker 1: at its core and the event horizon. And so this
30:54
Speaker 1: would be a very very dense object, even denser than
30:57
Speaker 1: neutron stars, but not actually a black hole, and quantum
31:00
Speaker 1: mechanics would be preventing that. And something else that's super
31:03
Speaker 1: fascinating about these objects is that they're not stable like
31:06
Speaker 1: a neutron star is stable. It's a balance between these
31:08
Speaker 1: two foss squeezing down gravity and pushing out because of
31:12
Speaker 1: the corks, this plank core is not actually stable. People
31:17
Speaker 1: think that quantum mechanics is more like a rubber sheet,
31:20
Speaker 1: you know that You're like it collapses and then it
31:22
Speaker 1: bounces back, so it provides like a maximum density or
31:25
Speaker 1: like a minimum size to this object, and then it
31:27
Speaker 1: pushes back and then the star expands again. But wouldn't
31:30
Speaker 1: that be evidence or an argument against these dark stars,
31:34
Speaker 1: Like if they don't last very long, why do we
31:36
Speaker 1: think they could exist, right, Well, they might not last
31:38
Speaker 1: that long in their own time, right, but the gravity
31:41
Speaker 1: is really really intense and so time is slowed down.
31:45
Speaker 1: So what these dark stars might be is like this
31:47
Speaker 1: object that's collapsing, that's going to bounce back from this
31:50
Speaker 1: plank core. But from our point of view, it might
31:53
Speaker 1: take billions or trillions of years for that bounds to
31:56
Speaker 1: happen because it's super slowed down by the gravity aational
32:00
Speaker 1: time dilation. So it looks stable to us on our
32:03
Speaker 1: time scale, but you know, if you're inside of it,
32:05
Speaker 1: the whole thing would be over in a blip. It's
32:07
Speaker 1: like a loophole. Like it's unstable and it won't last
32:10
Speaker 1: for long. But it depends on what you mean by long,
32:12
Speaker 1: all right, So so from our point of view it
32:14
Speaker 1: would look like a stable thing, but it's actually not. Yeah,
32:17
Speaker 1: and it doesn't have an event horizon, and so unlike
32:19
Speaker 1: a black hole, it could actually emit information. It could
32:23
Speaker 1: like actually leak photons. But I guess why is it
32:26
Speaker 1: dark and why is it emitting X rays but not
32:28
Speaker 1: visible light? Yeah? Great question, right, Because we have to
32:31
Speaker 1: match all the observations for these things to explain what
32:33
Speaker 1: we see. They have to actually predict what we see.
32:36
Speaker 1: So how could these things be dark? Again, it's gravity
32:39
Speaker 1: and the relativistic effects. If these things really do have
32:42
Speaker 1: this much gravity, because they're very, very dense objects, so
32:45
Speaker 1: much so that they have this crazy time dilation. They
32:48
Speaker 1: have another effect on things, which is that they read shift.
32:51
Speaker 1: So they might be emitting photons, but those photons would
32:54
Speaker 1: be shifted towards the red, so far towards the red
32:57
Speaker 1: that they're essentially invisible. Like, take a visible light photon
33:01
Speaker 1: that has a wavelength of you know, a few d
33:03
Speaker 1: nimes and stretch that thing out past infrared, out past radio,
33:08
Speaker 1: so it has like a wavelength you know, like the
33:09
Speaker 1: size of the galaxy, or maybe a little smaller. That
33:12
Speaker 1: would be a photon that's so big it would be
33:14
Speaker 1: almost invisible. And so this would look like a black hole. Wow,
33:17
Speaker 1: photon the size of a galaxy. That's wild. Well, let's
33:21
Speaker 1: get into why we think these dark stars might be
33:24
Speaker 1: real and whether or not they actually maybe supplanted black
33:29
Speaker 1: holes and make them not real. But first let's take
33:32
Speaker 1: another quick break. All right, we're talking about dark stars
33:47
Speaker 1: and whether the things that we call black holes are
33:50
Speaker 1: actually maybe not black holes, and maybe there are these
33:53
Speaker 1: dark stars, and so we talked about what those are. Now, Daniel,
33:57
Speaker 1: why do we think that maybe black holes are not
33:59
Speaker 1: black holes, but they're actually these so far theoretical dark stars. Yeah. Well,
34:03
Speaker 1: one reason is that black holes are a headache. You know,
34:06
Speaker 1: they don't really make sense. There's lots of puzzles, like
34:09
Speaker 1: they're fascinating, they're amazing, and they're sort of a fun headache.
34:13
Speaker 1: But you know, there's lots of things about black holes
34:15
Speaker 1: that we don't understand, like can a singularity be real?
34:19
Speaker 1: Is that something which actually exists in our universe? You know,
34:22
Speaker 1: as we said, general relativity predicts that singularities are real,
34:25
Speaker 1: but quantum mechanics says they can't exist. And so we've
34:28
Speaker 1: long struggled to understand that contradiction. And so this is
34:33
Speaker 1: sort of like a way around this to say, like, oh, well,
34:35
Speaker 1: maybe they just never happened and so we don't have
34:37
Speaker 1: to explain them. So would this supplant even like the
34:41
Speaker 1: black holes we think are at the center of galaxies,
34:44
Speaker 1: Like could those supermassive black holes in the center of
34:47
Speaker 1: galaxies that we know are humongous, could at those actually
34:50
Speaker 1: be dark stars? Or are we only talking about the
34:52
Speaker 1: smaller black holes. Now we're talking about all of them,
34:54
Speaker 1: so we could supplant all of them, and that You
34:56
Speaker 1: asked a question before the break about the X rays,
34:59
Speaker 1: like how do we ling the X rays and the
35:00
Speaker 1: other radiation because the supermassive black holes at the center
35:04
Speaker 1: of our galaxy. You know, from the actual black hole,
35:07
Speaker 1: there's no light right there black but around them are
35:10
Speaker 1: these crazy accretion disks of hot gas that are emitting
35:13
Speaker 1: X rays and other very high energy radiation. But that's
35:16
Speaker 1: just from the gravity of the object. And so a
35:18
Speaker 1: dark star with the same gravity as a black hole,
35:21
Speaker 1: but without the actual singularity in the event horizon would
35:24
Speaker 1: have the same gravitational impact on nearby stuff, heating it
35:27
Speaker 1: up and swirling it around and generating that same radiation.
35:31
Speaker 1: So yeah, you could have a huge dark star at
35:34
Speaker 1: the center of our galaxy that's like in the middle
35:36
Speaker 1: of a billion or trillion year collapse and rebounds out,
35:41
Speaker 1: but it looks to us like a black hole. I
35:43
Speaker 1: feel like you're kind of saying that maybe black holes
35:46
Speaker 1: in themselves are impossible, Like maybe it's impossible to have
35:49
Speaker 1: a black hole, and actually, like when you try to
35:52
Speaker 1: get a black hole, the most you get is one
35:54
Speaker 1: of these like super compressed dark stars which are being
35:57
Speaker 1: kind of prevented from collapse by quantum mechanics. Yeah, exactly.
36:02
Speaker 1: And so maybe the reason that black holes make no
36:04
Speaker 1: sense theoretically and inconsistent with quantum mechanics is because quantum
36:08
Speaker 1: mechanics prevents them from happening. Right, If the universe really
36:11
Speaker 1: does follow these rules of the uncertainty principle, then that's
36:14
Speaker 1: inconsistent with singularities, and so maybe the uncertainty principle prevents
36:18
Speaker 1: the singularity from ever forming. Oh man, I feel like
36:21
Speaker 1: you just blew my mind if you had how many
36:23
Speaker 1: podcasts about black holes and now you tell me like,
36:25
Speaker 1: maybe they're not actually real, Like maybe they're impossible. Yeah,
36:29
Speaker 1: and in some sense, like coming up with this other
36:32
Speaker 1: explanation for them solves all these other problems that black
36:35
Speaker 1: holes bring with them. Right, we've had multiple episodes about
36:38
Speaker 1: like the black hole information paradox. We know the quantum
36:41
Speaker 1: information is not destroyed, So what happens when things fall
36:44
Speaker 1: into a black hole? What happens to their information when
36:47
Speaker 1: the black hole eventually evaporates, We don't know. It's not
36:50
Speaker 1: something that makes any sense to us, and we can't
36:52
Speaker 1: explain because we have no good theory of quantum gravity
36:56
Speaker 1: that tells us what happens when there is gravity between
36:59
Speaker 1: part of goals. And so maybe the solution of that
37:02
Speaker 1: is just scratch black holes from the list of things
37:05
Speaker 1: we want to explain, right, we don't need to get
37:07
Speaker 1: about it, you know, like never mind, you know these
37:10
Speaker 1: things we've been talking about forever. Uh, whoops, never mind,
37:15
Speaker 1: it's actually not possible. Yeah, it's really fun idea, you know,
37:18
Speaker 1: like take something off your to do list by erasing
37:20
Speaker 1: it instead of doing it. I gotta clean the toilet. No,
37:25
Speaker 1: toilets don't exist. Done with that, Yeah, you're gonna have
37:28
Speaker 1: other problems if you think toilets don't exists. But the
37:32
Speaker 1: cool thing about dark stars is not only do they
37:35
Speaker 1: get rid of this thorny problem of black holes, but
37:38
Speaker 1: they could explain other mysteries of the universe that are
37:41
Speaker 1: out there. Yeah, other dark and mysterious stuff. Right. Yeah.
37:45
Speaker 1: For example, we've long wondered, you know, what is the
37:48
Speaker 1: stuff out there in the universe that's creating all this
37:51
Speaker 1: gravity that seems to be holding the galaxy together, some
37:55
Speaker 1: weird new kind of matter that we don't know what
37:57
Speaker 1: it is and we can't see it, but it has gravity,
38:00
Speaker 1: and it's affected the structure of the universe, and it
38:02
Speaker 1: affects how galaxies spin, and it seems to be everywhere
38:05
Speaker 1: and really important, and it's more of it. And then
38:07
Speaker 1: there is a normal matter, but we don't really know
38:09
Speaker 1: what it is and we haven't been able to see
38:11
Speaker 1: it or interact with it or detected. So this stuff
38:14
Speaker 1: dark matter. We have a long list of candidates for
38:16
Speaker 1: what it might be, but now because of dark stars,
38:20
Speaker 1: we have sort of a new candidate that appears on
38:22
Speaker 1: that list, and that's these crazy long wavelength photons. So
38:26
Speaker 1: you're saying that the light from these the dark stars
38:29
Speaker 1: is what could be dark k matter or are you
38:30
Speaker 1: saying that maybe the universe is like riddled and filled
38:33
Speaker 1: with tiny dark stars everywhere. You know, it's the light
38:36
Speaker 1: and the radiation from these dark stars. So these dark
38:39
Speaker 1: stars look a lot like black holes, but they do
38:42
Speaker 1: give off some light, but that light is invisible to
38:44
Speaker 1: us because it's so low frequency, and that light itself
38:48
Speaker 1: might be the dark matter. It could be that there's
38:51
Speaker 1: so much of it out there that the light itself
38:53
Speaker 1: is helping curve space. Because remember photons have no mass,
38:57
Speaker 1: but in general relativity, space bends in the presence of energy,
39:01
Speaker 1: not just mass, so photons can contribute to that. And
39:04
Speaker 1: so these things can contribute photons or even gravitons that
39:09
Speaker 1: are hard to detect, but overall, having lots and lots
39:11
Speaker 1: and lots of them around, they can bend the shape
39:14
Speaker 1: of space and exactly the way dark matter does. I
39:16
Speaker 1: feel like now you're saying that maybe dark matter doesn't exist,
39:19
Speaker 1: and really it's just dark light. Dark stars emitting dark
39:23
Speaker 1: photons could explain everything. But wouldn't black holes also emit
39:27
Speaker 1: you know, these dark photons, if black holes existed. But
39:30
Speaker 1: black holes don't emit anything, right, I mean, black holes
39:32
Speaker 1: don't emit light. The stuff around them emits light. But
39:36
Speaker 1: this is the one thing that would be different between
39:38
Speaker 1: black holes and dark stars. That these dark stars, because
39:40
Speaker 1: they don't have event horizons, they do emit light, and
39:43
Speaker 1: that light is crazy stretch to low frequencies by the
39:46
Speaker 1: gravitational strength of the dark star. Can we measure these
39:51
Speaker 1: long wavelength light? Can we have a detector to see
39:54
Speaker 1: if they're there? It's very difficult to interact with something
39:56
Speaker 1: that's such a long wavelength. They're basically just ignores you.
40:00
Speaker 1: That's why, for example, we do radio astronomy because radio
40:02
Speaker 1: waves can go through like clouds of gas and dust
40:05
Speaker 1: and tell us what's going on in the center of
40:06
Speaker 1: the galaxy. Because to them, the clouds of gas and
40:08
Speaker 1: dust are like nothing, and so it's very, very difficult
40:11
Speaker 1: to interact with those photons. You need a detector like
40:14
Speaker 1: the size of the galaxy almost in order to interact
40:17
Speaker 1: with them. I feel like you're telling me, like, maybe
40:19
Speaker 1: you know that dark matter halo that we know is
40:22
Speaker 1: or a cloud that is sort of covering our galaxy.
40:24
Speaker 1: Maybe it's just it's not dark matter. May it's just
40:26
Speaker 1: like one giant photon, like one one ginormous photon, you know,
40:33
Speaker 1: confusing us. That'd be hilarious if it's like, Hi, I'm Bob,
40:35
Speaker 1: I'm a photon and I've been the dark matter of
40:37
Speaker 1: the whole time. Yeah, there you go. We found our culprit.
40:43
Speaker 1: Why didn't you introduce yourself in Act one? Man? Why
40:45
Speaker 1: did you wait on to Act three? That's just bad
40:47
Speaker 1: mystery writing. Well, that's really interesting to think about. But
40:50
Speaker 1: you know, photons are quantized and really really low frequency
40:54
Speaker 1: photon would not have that much energy right, because the
40:56
Speaker 1: energy the photon depends on its wavelength. So in order
40:59
Speaker 1: to explain the dark no matter, you need a lot
41:01
Speaker 1: of these photons. They have to be Bob and like
41:03
Speaker 1: ten to the twenty seven of his friends. I think,
41:05
Speaker 1: kind of like the nuta book, they're fooling ice cream
41:08
Speaker 1: flavor of the galaxy. Yeah, and you know, this is
41:11
Speaker 1: a fun theory for people to think about, like could
41:13
Speaker 1: this be becauld it really exists out there in the universe.
41:16
Speaker 1: What are ways we could separate them from black holes
41:19
Speaker 1: that we could actually detect. But it's a new area.
41:22
Speaker 1: People are playing with it, you know. Carlo Rovelli wrote
41:24
Speaker 1: a fun paper about them. I read a few papers
41:26
Speaker 1: on this topic. It's still something that's in people's minds.
41:29
Speaker 1: I see, like we don't know if it's even possible
41:30
Speaker 1: to have these dark stars or whether they would just
41:33
Speaker 1: collapse into the black hole. Yeah, the signs of them
41:36
Speaker 1: is still very new and tentative, and people are doing
41:38
Speaker 1: calculations and making all sort of assumptions and disagreeing with
41:41
Speaker 1: each other about what these things might look like. It's
41:44
Speaker 1: really at the forefront of knowledge. But you know, black
41:46
Speaker 1: holes were at the forefront of knowledge. For decades before
41:48
Speaker 1: we understood really what they would mean and what they
41:51
Speaker 1: would look like in the universe, and so it might
41:53
Speaker 1: just take a little while for sort of like people
41:55
Speaker 1: to digest this stuff intellectually and figure out how to
41:58
Speaker 1: look for them correctly. Well, it's at that picture that
42:00
Speaker 1: we took up the black hole last year or two
42:02
Speaker 1: years ago. It was pretty convincing. But now when I
42:04
Speaker 1: look at it, and maybe I'll imagine a little tiny
42:07
Speaker 1: bob in the middle there laughing at us and twitterling.
42:10
Speaker 1: It's a mustache, yeh, exactly. Maybe it has a totally
42:13
Speaker 1: jet black mustache and you can't see it, and it's
42:17
Speaker 1: laughing at you and admitting dark matter. That's crazy. All right, Well,
42:21
Speaker 1: I guess once more the universe is full of potential surprises.
42:25
Speaker 1: And I guess the main lesson here is don't trust physicists.
42:29
Speaker 1: You know, maybe we're talking about this whole podcast. No,
42:34
Speaker 1: the lesson is fund physicists to think of crazy ideas,
42:38
Speaker 1: because they might find stuff that's actually out there, and
42:40
Speaker 1: then they might come up with even better explanations to
42:42
Speaker 1: describe what you see. We definitely need creative brain story
42:46
Speaker 1: about how the universe works. That's a good positive spin.
42:49
Speaker 1: All right, well, we hope you enjoyed that. Thanks for
42:51
Speaker 1: joining us, see you next time. Thanks for listening, and
43:02
Speaker 1: remember that Daniel and Jorge Explain the Universe is a
43:05
Speaker 1: production of I Heart Radio. Or more podcast from my
43:08
Speaker 1: heart Radio. Visit the I heart Radio app, Apple Podcasts,
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Speaker 1: or wherever you listen to your favorite shows.