Latest / Daniel and Kelly’s Extraordinary Universe / Could black holes actually be fuzzballs?

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Could black holes actually be fuzzballs? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Or hey, does your family have any pets these days?
0:11
Speaker 1: We have a wild rabbit that les to hang out
0:13
Speaker 1: in our yard. Does that count? Are you it's pet
0:16
Speaker 1: or is it yours? That's a great question. I'll have
0:20
Speaker 1: to ask the rabbit. Do you have a dog? Right? Yes,
0:23
Speaker 1: we have a wonderful little dog named Pepito, an immigrant
0:25
Speaker 1: from Incinada. Now, is he called Pepita because he's he's
0:29
Speaker 1: actually peppit or or a seed? He is quite peppy,
0:33
Speaker 1: but he is not a seed, but he came with
0:35
Speaker 1: that name, so we don't actually know why he was
0:37
Speaker 1: called Peppita. But interestingly, he does seem to violate the
0:40
Speaker 1: laws of physics. Wait, what what do you mean your
0:43
Speaker 1: dog travels back in time? Is it actually from the teacher? No,
0:47
Speaker 1: he's amazingly a short haired dog, but seems to shed
0:51
Speaker 1: enough hair that we find these incredible fur balls around
0:54
Speaker 1: the house. And that is why we don't have a pet.
0:59
Speaker 1: Does a dog actually clean up after itself at least? Oh?
1:01
Speaker 1: Absolutely not. He just seems to turn dog food into fur.
1:05
Speaker 1: But how does that violate the laws of physics? Because
1:07
Speaker 1: I swear the fur balls he produced I have more
1:09
Speaker 1: masks than the food we're feeding them. What Maybe the
1:12
Speaker 1: dog is from the future. Maybe dogs know more about
1:15
Speaker 1: physics than we do. That's an extraordinary claim. Daniel, are
1:18
Speaker 1: you sure about this? Have you actually run the experiments?
1:21
Speaker 1: If you wait, how much food you've give him versus
1:23
Speaker 1: you measured the mass these furballs. I'm still waiting to
1:26
Speaker 1: hear back on my grant proposal from the Daniel Science
1:28
Speaker 1: Foundation to study your dog. It's very niche organization. Sounds
1:33
Speaker 1: like you have to work on a no hair theorem
1:35
Speaker 1: for your dog. Hi am poor handmade cartoonists and the
1:53
Speaker 1: co author of Frequently Asked Questions about the Universe. Hi.
1:56
Speaker 1: I'm Daniel. I'm a particle physicist and a professor at
1:59
Speaker 1: uc or Rhyne, and I'm no longer the hairiest thing
2:02
Speaker 1: in my family. Oh that's good. Who's the Who's the
2:05
Speaker 1: next in line for your title? The dog is number one,
2:08
Speaker 1: and I'm number two, and who's number three? I think
2:11
Speaker 1: I want to answer that question exactly. Some things are
2:15
Speaker 1: best left of mystery in this universe. I believe it
2:18
Speaker 1: that as a mystery in the listeners imagination. Welcome to
2:21
Speaker 1: our podcast. Daniel and Jorge Explain the Universe, a production
2:24
Speaker 1: of I Heart Radio, in which we dig into the
2:26
Speaker 1: hairiest tangly mysteries about the universe. We want to understand
2:31
Speaker 1: how everything works. We want to pull it apart and
2:34
Speaker 1: straighten it out for you and for us. We want
2:37
Speaker 1: to walk you right up to the place where our
2:39
Speaker 1: brains get twisted into not trying to understand how this
2:44
Speaker 1: universe works, how we can describe it all using simple
2:47
Speaker 1: mathematical equations, and how we can talk about it to
2:50
Speaker 1: each other, to other physicists, and to you and to
2:53
Speaker 1: your dog. Maybe because it is a pretty incredible universe.
2:57
Speaker 1: It's a dog gone universe. And we love to answer
2:59
Speaker 1: questions here on the podcast, all kinds of questions, amazing, incredible,
3:03
Speaker 1: deep questions about the universe, and also pet questions that
3:06
Speaker 1: people have about how things work, and sometimes questions about
3:09
Speaker 1: their pets. I think if you offered my dog like
3:11
Speaker 1: a scratch on the head or the answer to one
3:14
Speaker 1: of the deepest questions in the universe, probably go for
3:16
Speaker 1: the scratch on the head. Maybe a scratch on the
3:18
Speaker 1: head is the answer to everything, Daniel. Seems like a
3:21
Speaker 1: pretty simple answer but deep profound at the same time.
3:24
Speaker 1: We all want a little scratch in our hands maybe
3:26
Speaker 1: the answer is the sort of scratch on that internal
3:29
Speaker 1: itch in your mind, the one that makes you curious
3:31
Speaker 1: about how everything works. Or maybe it's all relative as
3:34
Speaker 1: Einstein set you know, to dog, Maybe a scratch on
3:37
Speaker 1: the head is the answer to the universe. Well, we
3:39
Speaker 1: already know the answer to life, the universe and everything.
3:42
Speaker 1: That's forty two. We just need to know what the
3:44
Speaker 1: question was. How many scratches to your dog do you
3:46
Speaker 1: have to give to for it to be happy? Definitely
3:49
Speaker 1: more than forty two. I'm on like forty two never
3:52
Speaker 1: seems to lose interest. Sounds like you have a greedy pet.
3:55
Speaker 1: Petpito is a wonderful addition to our family. We do
3:58
Speaker 1: like to answer questions here in the podcast, and we
4:01
Speaker 1: like to answer questions not just that people have in
4:03
Speaker 1: mind that are they're curious about it, but also questions
4:06
Speaker 1: that even physicists are answering at the cutting edge of
4:09
Speaker 1: our knowledge of the universe. That's right. The goal of
4:12
Speaker 1: physics is not just to explain why cannonballs fly over
4:15
Speaker 1: castle walls or why the Earth goes around the Sun,
4:19
Speaker 1: but to explain everything in the universe. We seek a unified,
4:23
Speaker 1: holistic description of the entire universe in terms of a
4:27
Speaker 1: simple equation the basic rules by which the universe runs,
4:31
Speaker 1: and that means that we have a pretty tall order.
4:33
Speaker 1: We have to explain everything that's out there. One thing
4:37
Speaker 1: that breaks the rule means the rule is not the
4:39
Speaker 1: right rule. So we go out there and look for
4:42
Speaker 1: the most extreme, the craziest, the bonkers situations where our
4:46
Speaker 1: understanding of the universe bends and breaks and snaps. That
4:50
Speaker 1: also gives us an opportunity to be creative and think
4:52
Speaker 1: about what is out there beyond our understanding. Yeah, because
4:56
Speaker 1: there are still big questions about the universe, big holes
4:59
Speaker 1: in our a theory of how everything works. May one
5:02
Speaker 1: of the biggest holes in our theory and our understanding
5:04
Speaker 1: of the universe is actually a hole, or at least
5:07
Speaker 1: we call it a hole. These objects that we call
5:09
Speaker 1: black holes are an enduring mystery and really capture the
5:12
Speaker 1: fascination not just of scientists but of the general public
5:16
Speaker 1: because they are so weird. We've been studying what we
5:19
Speaker 1: think our black holes for a few decades now, and
5:21
Speaker 1: yet deep questions remain about what might be inside them
5:25
Speaker 1: and if they are in fact black holes after all,
5:28
Speaker 1: you mean, they might not be holes. Maybe they're more
5:31
Speaker 1: like a ditch, Is that what you're saying, more like
5:33
Speaker 1: a dog, like something a dog would do in your
5:36
Speaker 1: yard to bury a bone. Well, they are very frustrating
5:39
Speaker 1: to study because you cannot see them directly because they
5:43
Speaker 1: are black, and so proving that something is a black
5:46
Speaker 1: hole is really quite challenging because you have to develop
5:49
Speaker 1: theories for how a black hole would look different from
5:51
Speaker 1: some other idea that also looks black. And you can't,
5:54
Speaker 1: of course go inside a black hole. So any proof
5:58
Speaker 1: that a black hole exists has to come from the outside,
6:01
Speaker 1: which means it has to be a little bit indirect.
6:03
Speaker 1: That forces us to develop like clever theories for what
6:06
Speaker 1: might be going on inside and to try to find
6:08
Speaker 1: hints for how that inside might somehow affect the outside
6:12
Speaker 1: where we live. You have to say, Daniel, I felt
6:14
Speaker 1: a little betray when you told me that black holes
6:17
Speaker 1: might not exist. I feel like we've been talking about
6:19
Speaker 1: them as if they exist for so long and then
6:21
Speaker 1: suddenly tell me that it's just kind of a little
6:24
Speaker 1: bit of a theory right now, we don't actually know
6:26
Speaker 1: they exist. Yeah, Well, there's always nuance to this understanding, right, Like,
6:30
Speaker 1: in the end, what do we really know about the
6:32
Speaker 1: nature of the universe. We have experiments which verify our models,
6:35
Speaker 1: but there are always questions there. There's always a level
6:39
Speaker 1: of refinement. There's always more to learn about what's really
6:42
Speaker 1: going on out there in the universe. And black holes
6:44
Speaker 1: are very slippery because they are so indirect. Unlike electrons
6:49
Speaker 1: or other things. You can't observe them directly. You can
6:52
Speaker 1: only see their influence on the parts of the universe
6:55
Speaker 1: that are near them. Well, that's a philosophical question. Can
6:57
Speaker 1: a black hole be slippery? You lose grasp of a
7:00
Speaker 1: black hole? I guess you studied it with physics. Theoretically
7:05
Speaker 1: and conceptually, they are very slippery. It's hard to hold
7:08
Speaker 1: a black hole in your mind. And you know, we
7:09
Speaker 1: don't even really have a great idea for what a
7:12
Speaker 1: black hole is, put aside all the crazy alternative ideas.
7:16
Speaker 1: Even the concept of a black hole is not super
7:19
Speaker 1: well defined right now in modern physics, because we have
7:22
Speaker 1: two descriptions of the universe, quantum mechanics and general relativity,
7:26
Speaker 1: and they disagree about what might be happening at the
7:29
Speaker 1: heart of a black hole. Yeah, it's hard to hold
7:31
Speaker 1: a black hole in your mind, and also in your hand.
7:33
Speaker 1: I hear, that's a bad idea, not recommended. Leave that
7:37
Speaker 1: black hole at the dollar store. Even if it's just
7:39
Speaker 1: a dollar, it's not worth it. Can you play catch
7:41
Speaker 1: with your pet with a black hole? Depends on how
7:44
Speaker 1: much you like your pet. I guess my pet does
7:46
Speaker 1: seem like a black hole. He just like inhales. All
7:48
Speaker 1: of that dog food is incredible, and those head scratches
7:51
Speaker 1: as well, I'm sure. But it is interesting that black
7:53
Speaker 1: holes may not be actually black holes. They could be
7:56
Speaker 1: something else. Physicists think, maybe something fuzzy, because in the
8:00
Speaker 1: end we are left to infer what might be in
8:02
Speaker 1: those crazy dark patches of space that we can't see directly.
8:07
Speaker 1: So theorists have been very creative coming up with all
8:09
Speaker 1: sorts of alternative suggestions for what might be sitting there
8:13
Speaker 1: in the blackness to be On the podcast, we'll be
8:15
Speaker 1: asking the question, what if black holes are actually fuzzballs?
8:26
Speaker 1: Daniel at these fuzzballs or fun balls? Are they fun fuzzball?
8:30
Speaker 1: I don't think they would be very fun to fall into,
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Speaker 1: even if they are actually part of the universe. It's
8:36
Speaker 1: never fun to fall into a hole, but they are
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Speaker 1: fun to think about and to imagine, and all the
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Speaker 1: artists conceptions of fuzzballs I fund on the internet are
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Speaker 1: pretty fun to look at. I think anything on the
8:47
Speaker 1: Internet is probably fun to look at. Out to a
8:49
Speaker 1: point perhaps to be careful about googling fuzzy balls on
8:52
Speaker 1: the internet, though, or any kind of balls really, or
8:56
Speaker 1: really anything on the Internet. Be careful of the Internet
9:00
Speaker 1: in general. You might fall into a black hole looking
9:04
Speaker 1: up random things. But as usually, we were wondering how
9:07
Speaker 1: many people out there had considered the question where their
9:09
Speaker 1: black holes could actually be fuzzballs. I imagine this is
9:12
Speaker 1: not a question people ask themselves every day. That's the
9:15
Speaker 1: job of physics, though, right to raise the deep dark
9:18
Speaker 1: questions about the universe, sorry, the deep dark questions, and
9:21
Speaker 1: the fuzzy questions as well. Daniel went out there into
9:24
Speaker 1: the Internet to ask people what is a fuzzball? So
9:28
Speaker 1: thanks very much everybody who volunteers for these. If you
9:31
Speaker 1: would like to participate for a future episode so that
9:34
Speaker 1: other people can hear your ideas about some difficult questions
9:37
Speaker 1: in physics, please don't be shy. Right to us two
9:40
Speaker 1: questions at Daniel and Jorge dot com. Here's what people
9:43
Speaker 1: have to say, possible is a type of baseball that
9:46
Speaker 1: it's playing the windowsill. And I'm sure I'm right, but
9:54
Speaker 1: it's not this type of baseball, not you asking me about.
10:00
Speaker 1: And I'm really curious what would be it? So what
10:04
Speaker 1: is fusiball? Fussiball? It sounds like something a cat would
10:08
Speaker 1: choke up. I've heard of the no hair theorem for
10:11
Speaker 1: black holes, so I'm guessing a fuzzball is the inverse
10:15
Speaker 1: theorem for white holes. A fuzzball is a little bit
10:19
Speaker 1: of lint that you pick off your sweater. I don't
10:23
Speaker 1: know what a fuzzible is, but if I had to
10:25
Speaker 1: take a guess, I think it's a collection of nucleons um.
10:31
Speaker 1: I don't know, all right, A lot of people associated
10:34
Speaker 1: this with pets as well. I didn't give people clues
10:37
Speaker 1: about black holes. I just wanted to know if they
10:39
Speaker 1: had heard the idea of a physics fuzzball. Someone thought
10:42
Speaker 1: it was maybe a type of pitch that you do
10:45
Speaker 1: in baseball. Isn't they also a drink? Isn't there a
10:48
Speaker 1: drink called a fuzzball or something? Everything is a drink
10:51
Speaker 1: these days? Some people they did associated with maybe black holes, right,
10:55
Speaker 1: They mentioned no hair theorem. Yeah, that's another tortured analogy
10:59
Speaker 1: in physics whether black holes have hair or not. So
11:02
Speaker 1: fuzzballs are sort of the other extreme. They're like the
11:04
Speaker 1: hairiest possibility for a black hole. That doesn't necessarily make
11:09
Speaker 1: them white holes. Though someone mentioned cats that they like
11:13
Speaker 1: the balls that cats regurgitate, yet another reason not to
11:16
Speaker 1: have pets. That's are wonderful additions to the family. Man,
11:19
Speaker 1: I encourage everybody out there to adopt a dog, or
11:21
Speaker 1: a cat or a wild rabbit. So this is an
11:24
Speaker 1: interesting question. Are black holes actually fastballs? I'm curious to
11:27
Speaker 1: know how this came up, Like who's that in their
11:29
Speaker 1: couch one day and thought, hey, I wonder if a
11:31
Speaker 1: black hole could be a fuzzball. Well, there's a big
11:33
Speaker 1: opportunity there in physics to solve one of the deepest
11:37
Speaker 1: outstanding questions, which is who describes the universe that we
11:41
Speaker 1: live in. Is it general relativity that tells us that
11:45
Speaker 1: space is smooth and continuous and classical, that objects move
11:50
Speaker 1: in smooth paths through that space, or is it quantum
11:54
Speaker 1: mechanics that tells us that everything is discreet and that
11:57
Speaker 1: objects don't have smooth classical paths. They have probabilities to
12:02
Speaker 1: be here and then probabilities to be there, but they
12:04
Speaker 1: don't have to go from here to there, and that
12:07
Speaker 1: space itself might actually be discreete. These two things are
12:10
Speaker 1: in conflict at the heart of a black hole. The
12:12
Speaker 1: description of a black hole in general relativity is inconsistent
12:16
Speaker 1: with our understanding of quantum mechanics. So there's definitely an
12:20
Speaker 1: opportunity here to be creative. Well, at least the conflict
12:23
Speaker 1: is inside of what we think might be a black hole.
12:25
Speaker 1: We don't know exactly. We don't know what's out there
12:28
Speaker 1: in the universe, but whatever is out there in the
12:29
Speaker 1: universe has to be following some rules, right. We think
12:33
Speaker 1: that the universe does follow laws, and that we can
12:36
Speaker 1: discover those through creativity and experimentation. And so something is
12:41
Speaker 1: happening out there. And if we could only see what
12:43
Speaker 1: was going on at the heart of a black hole
12:45
Speaker 1: or whatever thing is there in those black spots in space,
12:49
Speaker 1: then we could get a clue as to what rules
12:51
Speaker 1: it's following. All right, Well, let's dig into it, and
12:53
Speaker 1: let's start with the basics. I guess for those listeners
12:56
Speaker 1: that are not so familiar with black holes, Daniel, what
12:58
Speaker 1: are the basics of black holes, Why are they? Why
13:00
Speaker 1: do we think we've seen them? So it comes out
13:02
Speaker 1: of predictions from general relativity. About a hundred years ago,
13:06
Speaker 1: Einstein developed his theory that gravity is not a force
13:10
Speaker 1: between two objects with mass like Newton thought, where the
13:13
Speaker 1: Earth's gravity, for example, pulls on an apple or the
13:16
Speaker 1: Sun's gravity pulls on the Earth. Instead, Einstein said that
13:19
Speaker 1: space is bent by the presence of mass. But you
13:22
Speaker 1: can't see this bending directly, Like you have a chunk
13:25
Speaker 1: of space in front of you. It would look the
13:27
Speaker 1: same if it was curved or not curved, until you
13:30
Speaker 1: try to pass something through it. You shine light beams
13:32
Speaker 1: through space that's not curved, for example, and they just
13:35
Speaker 1: go through parallel. You shine light beams through space that
13:37
Speaker 1: is curved, then they change direction. But because we can't
13:41
Speaker 1: see that curvature directly, like with our own eyes, then
13:44
Speaker 1: it looks like there's a force there. It's sort of
13:47
Speaker 1: like if you were watching a soccer game and you
13:50
Speaker 1: could only see the ball and not the players, you
13:52
Speaker 1: would imagine, oh, there's something out there applying a force
13:55
Speaker 1: to the ball because it's changing direction, right, And the
13:58
Speaker 1: same way we see things moving paths that don't seem
14:01
Speaker 1: natural to us. The Earth moves in a path around
14:03
Speaker 1: the Sun, so we imagine a force of gravity, and
14:06
Speaker 1: actuality is just space being curved. So Einstein came up
14:09
Speaker 1: with this description of gravity as bending of space, and
14:13
Speaker 1: people played with it and thought, well, how much can
14:15
Speaker 1: space get bent? And it's about a hundred years ago.
14:18
Speaker 1: People came up with this solution to Einstein's equations that
14:20
Speaker 1: predicted that if you've got enough mass in one little spot,
14:23
Speaker 1: it would compactify itself so much that space would curve
14:26
Speaker 1: infinitely and the things that got really close to it
14:29
Speaker 1: would be trapped forever. It's kind of natural to think
14:32
Speaker 1: of gravity as a force, right, I mean, we sort
14:34
Speaker 1: of looked at electromagnetic forces. We saw magnets, you know,
14:38
Speaker 1: repel each other. We see that you can push against
14:40
Speaker 1: your chair and things like that. Those are still forces, right,
14:42
Speaker 1: and so it was I guess natural to think of
14:44
Speaker 1: gravity also. And it is natural to think of gravity
14:47
Speaker 1: also as a force. Yeah, there are definitely forces in
14:50
Speaker 1: the universe, and we've been able to describe them with theories,
14:52
Speaker 1: first classical theories like of electromagnetism and now quantum field
14:56
Speaker 1: theories of electromagnetism. So it's reasonable to say a b
15:00
Speaker 1: gravity is a force. Einstein's description of gravity is that
15:03
Speaker 1: it's not a force, is that it's a bending of space.
15:06
Speaker 1: It's a fictitious force that comes out of our inability
15:09
Speaker 1: to see that bending, and fictitious forces like this occur,
15:12
Speaker 1: and lots of other situations. Imagine, for example, you are
15:15
Speaker 1: on a Merry go Round and you try to throw
15:17
Speaker 1: a ball to your friend. Well, the ball wouldn't move
15:19
Speaker 1: in what looks to you like a straight line because
15:22
Speaker 1: the Merry go Round is spinning, and so you might imagine, oh,
15:24
Speaker 1: there's some force they're pushing the ball sideways. It's a
15:28
Speaker 1: fictitious force. It's just because your Merry go Round is spinning.
15:31
Speaker 1: Is no real force there. And so that's just Einstein's
15:33
Speaker 1: description of it. And you know, that works really well,
15:36
Speaker 1: and it predicts lots of things in our universe, and
15:39
Speaker 1: it's been tested out the wazoo. But fundamentally it is
15:41
Speaker 1: inconsistent with quantum mechanics. And yet as we look out
15:45
Speaker 1: into the universe, we do see some evidence for these
15:48
Speaker 1: black holes being out there. Well, I think that that's
15:50
Speaker 1: why you brought up general relativity, is because black holes
15:53
Speaker 1: were originally thought of because of this idea of relativity, right,
15:57
Speaker 1: I mean, it was initially kind of a theoretical concept.
16:00
Speaker 1: For about fifty years, it was only theoretical. People were
16:03
Speaker 1: playing around with this in the math you know, Einstein
16:05
Speaker 1: came up with this description of the universe, and then
16:08
Speaker 1: people are explored it mathematically and said, well, what else
16:10
Speaker 1: can this do? What is this predict about the universe?
16:13
Speaker 1: And this is a pretty basic process in physics, right.
16:15
Speaker 1: We come up with a description of what we see,
16:17
Speaker 1: what we think we understand, and then we tested in
16:20
Speaker 1: other scenarios. We try to understand its limitations and its strengths.
16:24
Speaker 1: And so people playing with the mathematics came up with
16:27
Speaker 1: this prediction of a singularity, although it took them a
16:29
Speaker 1: long time to even develop the mathematical concept of an
16:33
Speaker 1: event horizon, that something coming close to this object in
16:37
Speaker 1: space would be trapped and never be able to escape.
16:40
Speaker 1: And it was more than fifty years before we saw
16:42
Speaker 1: sort of any evidence that these things were actually out
16:44
Speaker 1: there in the universe. But I wonder if someone have
16:47
Speaker 1: come up with the idea of a black hole without
16:49
Speaker 1: general relativity, Like can you just imagine something having so
16:52
Speaker 1: much density and so much maths that the force of
16:55
Speaker 1: gravity is too much even for light. Yeah, the idea
16:58
Speaker 1: of an object so massive that it might pull light
17:01
Speaker 1: to its surface pre dates general relativity. It comes from
17:05
Speaker 1: like the middle of the seventeen hundreds, where people were
17:07
Speaker 1: thinking about very massive objects. So even in Newtonian gravity,
17:10
Speaker 1: people were wondering, like, is it possible to pull on light? Remember,
17:14
Speaker 1: back then we didn't even know what light was. The
17:17
Speaker 1: theory of light as electromagnetic radiation didn't come to like
17:19
Speaker 1: a hundred years after that. So people have been playing
17:22
Speaker 1: around with these ideas before relativity. Wait what So then
17:26
Speaker 1: people came up with black holes in the middle of
17:27
Speaker 1: the seventeen century. Not the name maybe, but you know,
17:31
Speaker 1: if you imagine a planet so dense that it trapped light,
17:33
Speaker 1: then that's basically a black hole, isn't it. Yeah. It
17:36
Speaker 1: was seventy four a guy named John Mitchell was wondering
17:39
Speaker 1: what happens if you make a star so massive, it's
17:42
Speaker 1: gravity so strong that essentially it's escape velocity would be
17:46
Speaker 1: at the speed of light. He was just doing a
17:48
Speaker 1: mental thought experiment, and he thought, well, any light that
17:50
Speaker 1: leaves that would not be able to escape, and it
17:53
Speaker 1: would essentially come back to the star. He called these
17:56
Speaker 1: things dark stars, not black holes. M interesting. Wow, So
18:01
Speaker 1: maybe we should just call black holes dark stars, although
18:04
Speaker 1: dark stars are now used to describe something else that
18:07
Speaker 1: we talked about on the podcast recently, which is a
18:09
Speaker 1: different quantum mechanical version of a black hole. So that
18:11
Speaker 1: name has already been used twice. It's in there like
18:14
Speaker 1: an International Copyright Office for physics names. If you file
18:18
Speaker 1: an nobody else can use that name. Shouldn't there be one?
18:21
Speaker 1: Like why if I come up with a new consept
18:23
Speaker 1: then I call it a black hole? Can I do that?
18:25
Speaker 1: You can try. I don't know if anybody is going
18:27
Speaker 1: to use it. It's sort of the wild wild West
18:29
Speaker 1: out there. All right. Well that's the basics of black holes,
18:32
Speaker 1: and so let's get into whether we see black holes
18:35
Speaker 1: and whether they're even holes at all. They might not
18:37
Speaker 1: be holes, they might be fuzzy balls. But first let's
18:40
Speaker 1: take a quick break. Alright, we're talking about pets. I
18:55
Speaker 1: guess holes and black holes and fuzzballs. Somehow it all
18:59
Speaker 1: makes sense because pets are fuzzy usually, and black holes
19:02
Speaker 1: are bad pets. Please don't get a black hole for
19:05
Speaker 1: your pet. Yeah, it'll eat everything, I mean literally everything
19:09
Speaker 1: in your house, and then your neighbor's house, and then
19:11
Speaker 1: your neighbor's neighbor's house, and then your neighbor's neighbor's pets
19:14
Speaker 1: as well. But yeah, we're talking about whether black holes
19:16
Speaker 1: are actually hold. Maybe they're not black holes, and they
19:19
Speaker 1: might be something called a fuzzball. Is that the actual
19:22
Speaker 1: physics name fuzzball? That is the actual physics name a fuzzball.
19:25
Speaker 1: And so with the whole judgment until you hear more
19:27
Speaker 1: about what it is. But I think it's not a
19:29
Speaker 1: terrible description of this theoretical idea. Well, let's find out.
19:33
Speaker 1: Now we're talking about the basics of a black hole,
19:36
Speaker 1: which is like a play sorce. Space is so bent
19:39
Speaker 1: by the density of matter that an energy that it
19:42
Speaker 1: sucks up even light. Now, Daniel, we've seen black hole now, right,
19:45
Speaker 1: a couple of years ago. Now, they've had pictures of
19:47
Speaker 1: black holes, so we know they exist. There are pictures
19:49
Speaker 1: on the internet of black holes that look like big,
19:53
Speaker 1: giant black holes. Yeah, if there are pictures on the Internet,
19:56
Speaker 1: then it must be true. Right, I've also seen pictures
19:58
Speaker 1: of Jedi warriors on the internet. Are you saying NASA
20:01
Speaker 1: put out tissues from images. No, Unfortunately, I'm going to
20:05
Speaker 1: give you a very legalistic quibble about the definition of
20:08
Speaker 1: the word seen. Right, So we have an image of
20:11
Speaker 1: a black hole, but does that mean that we have
20:13
Speaker 1: seen a black hole? I think if you have an
20:16
Speaker 1: image of something that you've captured, then yeah, you've technically
20:20
Speaker 1: seen it. I mean, I suppose if you keep the
20:21
Speaker 1: lens cap on your camera and you take a picture
20:23
Speaker 1: and you have a pure black image, have you taken
20:26
Speaker 1: a picture of the inside of your lens cap or
20:28
Speaker 1: is it just sort of a non picture? Wait? Wait, wait,
20:30
Speaker 1: what of the wait what? Yeah? Technically if I take
20:34
Speaker 1: a picture of your inside of your let's cap, is
20:38
Speaker 1: that what you're saying? Yeah? I mean the issue here
20:40
Speaker 1: is that we don't see any photons from a black hole,
20:43
Speaker 1: or in a black hole, if it exists, wouldn't give
20:46
Speaker 1: off any light. So the only thing we can do
20:48
Speaker 1: is look at the impact of the black hole on
20:50
Speaker 1: nearby space and ask is that consistent with what we
20:54
Speaker 1: expect from a black hole. That doesn't tell us necessarily
20:57
Speaker 1: that the black hole is there. The history of the
21:00
Speaker 1: discovery of black hole in the sort of slowly accumulating
21:03
Speaker 1: evidence for their existence is all a little bit indirect.
21:07
Speaker 1: It's all evidence for what black holes do to the
21:09
Speaker 1: stuff near them. I see you're getting a little technical
21:13
Speaker 1: here on the definition. But um well, let's maybe step
21:15
Speaker 1: people through it. How do we know black holes actually
21:18
Speaker 1: sort of exists because we've seen different kinds of evidence
21:21
Speaker 1: for them. Right, it dates back to the mid sixties.
21:24
Speaker 1: The first evidence we had that suggested the black holes
21:27
Speaker 1: might be real were very bright X ray sources. Now,
21:30
Speaker 1: remember black holes, they don't emit any light because any
21:32
Speaker 1: light that hits them gets absorbed, and they don't give
21:35
Speaker 1: off any light because the event horizon. But they're typically
21:38
Speaker 1: surrounded by stuff that's very affected by the strong gravity.
21:42
Speaker 1: So if you have a bunch of gas and dust
21:43
Speaker 1: that's about to fall into the black hole, and the
21:46
Speaker 1: intense gravity makes it very very hot, and so it
21:48
Speaker 1: emits in the X rays. So in the sixties, people
21:51
Speaker 1: saw these X rays from a spot in the sky
21:53
Speaker 1: that they didn't see anything else. It's called sidneys X one,
21:56
Speaker 1: and they didn't really understand it. And then later people
21:58
Speaker 1: were studying a blue super giant which seemed to have
22:01
Speaker 1: some heavy object orbiting it that was emitting X rays
22:04
Speaker 1: but otherwise totally dark. So these are sort of like
22:06
Speaker 1: the first clues that there was something massive with very
22:09
Speaker 1: strong gravity that wasn't giving off any light, right, Because
22:13
Speaker 1: it's weird for something not to emit regular light, but
22:16
Speaker 1: for it to admit X rays, which is also light,
22:19
Speaker 1: but it's just light in a different frequency. So it's
22:21
Speaker 1: weird for something to emit X rays but not regular light. Right. Yes,
22:24
Speaker 1: stuff in the universe emits light based on its temperature. Right.
22:28
Speaker 1: As stuff gets hotter, it emits light in higher and
22:31
Speaker 1: higher frequencies. So the Sun emits in the visible light
22:34
Speaker 1: because of its temperature, the Earth emits in the infrared
22:36
Speaker 1: because of its temperature. Very very hot gases out there
22:39
Speaker 1: in the universe emit X rays because they're very very hot,
22:43
Speaker 1: And so here we have a very compact source of
22:45
Speaker 1: X rays, but we don't understand what the object is
22:47
Speaker 1: because it's not emitting in any other frequencies, right, And
22:50
Speaker 1: so they thought if it's only emitting super duper high
22:53
Speaker 1: frequency light, then it must be something extreme, like maybe
22:56
Speaker 1: a black hole exactly. And that's also similar to the
23:00
Speaker 1: picture that we've seen of a black hole. What is
23:02
Speaker 1: that a picture of Well, if you look at it,
23:05
Speaker 1: it's a ring of glowing gas and at the center
23:08
Speaker 1: it's black. So the part that you're actually seeing is
23:11
Speaker 1: the ring of gas around the black hole. It's emitting light,
23:14
Speaker 1: it's emitting X rays because it's super duper hot. And
23:17
Speaker 1: that's the picture that we've seen. What are we seeing
23:20
Speaker 1: from the actual black hole itself? If it's there, What
23:22
Speaker 1: we're seeing no photons, it's like you're seeing the inside
23:25
Speaker 1: of your camera lens cap right, Right, Well, let's get
23:28
Speaker 1: to the picture. But first let's talk about some of
23:30
Speaker 1: the other ways we've seen black holes, right, because we
23:32
Speaker 1: know they're they're also from their gravity, right exactly. We
23:35
Speaker 1: can find places in space where there's very intense gravity
23:39
Speaker 1: but no obvious source of it, like the center of
23:41
Speaker 1: the Milky Way. When we look at stars in the
23:43
Speaker 1: very center of the Milky Way, we see them going
23:45
Speaker 1: really really fast and then changing direction on these very
23:48
Speaker 1: tight orbits, as if there was a very heavy object
23:51
Speaker 1: right there at the center of the Milky Way. And
23:53
Speaker 1: folks in nearby U. C. L A. Won the Nobel
23:55
Speaker 1: Prize for this discovery last year. They've been tracking these
23:58
Speaker 1: stars for like twenty years. Recons directing their orbits, and
24:00
Speaker 1: the orbits are consistent with some very massive object at
24:04
Speaker 1: the heart of our galaxy, and yet it admits no
24:07
Speaker 1: light directly. So that's very suggestive of the existence of
24:11
Speaker 1: a black hole. Right, We've all the same black holes
24:13
Speaker 1: sort of through gravitational waves, right, Yeah, any object in
24:17
Speaker 1: the universe that accelerates is going to give off gravitational waves.
24:20
Speaker 1: That just means that everything that has mass has a
24:22
Speaker 1: gravitational field, right it pulls on things or bends space
24:26
Speaker 1: in a certain way. If that thing now accelerates, then
24:29
Speaker 1: that gravitational field changes. Just like if you delete an
24:32
Speaker 1: object from space or add an object to space, you're
24:35
Speaker 1: changing the gravitational field and that information propagates out through space.
24:39
Speaker 1: You don't instantly change the gravitational field of the Sun.
24:42
Speaker 1: If you deleted it, the change in the field would
24:44
Speaker 1: propagate out through space. So gravitational waves are essentially just
24:49
Speaker 1: updates to the gravitational field because something has changed. They
24:53
Speaker 1: have a really big, heavy object and you accelerate it.
24:55
Speaker 1: For example, if two black holes are orbiting each other
24:58
Speaker 1: and then they're falling into awards each other and becoming
25:01
Speaker 1: one single massive black hole, then you will see gravitational
25:04
Speaker 1: waves from those orbits, and we have seen that, we've
25:07
Speaker 1: seen a bunch of those things. What is that actually
25:10
Speaker 1: evidence of its evidence that some very dense, massive objects
25:13
Speaker 1: were orbiting each other and collapsed into one. Right, So
25:17
Speaker 1: it seems like maybe, you know, at the beginning of
25:19
Speaker 1: the last century, we came up with this idea more
25:21
Speaker 1: officially over a black hole. And over the years we
25:24
Speaker 1: saw all this evidence that you know, there are really
25:27
Speaker 1: super duper dance things out there in space that are
25:31
Speaker 1: not bright, so they're not like stars. They don't seem
25:34
Speaker 1: to emit regular light, only X ray, which is the
25:36
Speaker 1: super intense kind of light. And so people thought, hey,
25:39
Speaker 1: that maybe those those things, those super dense objects are
25:42
Speaker 1: black holes. But then actually a few years ago they
25:44
Speaker 1: saw they we got pictures of a black hole. But
25:47
Speaker 1: now you're telling me that made black holes are not
25:49
Speaker 1: black holes. Well, all that evidence is a little bit indirect.
25:53
Speaker 1: It supports the conclusion that there's something small, something dark,
25:56
Speaker 1: and something heavy, right, but not exactly what it is is.
26:00
Speaker 1: And for a long time, the only thing in our
26:02
Speaker 1: sort of category of ideas that could be that small, dark,
26:06
Speaker 1: and heavy were black holes. So that was evidence that
26:09
Speaker 1: black holes exist because we see things out there that
26:12
Speaker 1: are consistent with black holes, and there were no other candidates.
26:15
Speaker 1: And one thing to keep in mind is sort of
26:17
Speaker 1: how close to the black hole our observations come. When
26:20
Speaker 1: you think about like stars orbiting the central black hole
26:23
Speaker 1: in the Milky Way, they don't ever really get that
26:26
Speaker 1: close to the black hole. So yeah, it could be
26:28
Speaker 1: a black hole. It could also just be some really
26:30
Speaker 1: big dark object not a black hole, because the stars
26:33
Speaker 1: don't get close enough to distinguish between those scenarios. So
26:37
Speaker 1: what was exciting about the black hole image is that
26:40
Speaker 1: now we're looking directly at the gas that's right around
26:43
Speaker 1: the black hole, it really shows us sort of how
26:45
Speaker 1: small the black hole or whatever this massive object is
26:49
Speaker 1: has to be. So again, the black hole image doesn't
26:51
Speaker 1: tell us definitively that it is a black hole. It
26:54
Speaker 1: just says, well, whatever it is, it's very very small.
26:57
Speaker 1: It's smaller than any other picture or any other measure.
27:00
Speaker 1: It told us it had to be, right, But I
27:02
Speaker 1: feel like the image, you know, it shows an aero
27:04
Speaker 1: space out of which no light seems to be escaping, right,
27:08
Speaker 1: is something small, something dan, something that not even light
27:11
Speaker 1: can escape isn't that the definition of a black hole.
27:13
Speaker 1: Wouldn't you just say, look at that giant black dot
27:16
Speaker 1: and say, hey, that's a black hole because it's a
27:18
Speaker 1: hole and it's black. Well, we don't see any light
27:20
Speaker 1: from it, right, but it's not definitive proof that there
27:22
Speaker 1: is an actual event horizon there. We don't know that
27:25
Speaker 1: there's an event horizon. Well, we talked on the podcast
27:28
Speaker 1: once about this other idea of a dark star. Maybe
27:31
Speaker 1: black holes don't have an event horizon. But the intense
27:34
Speaker 1: gravity of a collapsing star bends space and so it
27:39
Speaker 1: like stretches all the light to super long frequencies like
27:43
Speaker 1: massively red shifts and everything, and slows down time so
27:47
Speaker 1: that it looks like no light is emitted. But the
27:49
Speaker 1: light that submitted is just like very low intensity because
27:52
Speaker 1: time is slowed, and very long wavelength like the wavelength
27:56
Speaker 1: of the galaxy, which makes it impossible to see. We
27:59
Speaker 1: couldn't disting whish between those two scenarios. Wait, you're saying
28:02
Speaker 1: that maybe there's something there that it could be that
28:05
Speaker 1: we're just seeing a black spot that's not trapping light,
28:09
Speaker 1: it's just maybe stretching light beyond our sensors. Exactly. We
28:12
Speaker 1: don't definitively know that it's an event arise, and we
28:15
Speaker 1: haven't been there to test it, to observe it closely
28:18
Speaker 1: and directly. We're very very far away from these things,
28:20
Speaker 1: and all we're seeing is a lack of photons. But
28:23
Speaker 1: there are other ways to explain a lack of photons, right,
28:26
Speaker 1: like massive gravitational redshift from an object that doesn't actually
28:31
Speaker 1: have an event horizon where it's technically possible for it
28:34
Speaker 1: to mat radiation. We wouldn't notice or be able to
28:37
Speaker 1: observe that radiation. Right. But isn't it a little suspicious
28:40
Speaker 1: that you see this ring of light, right, and then
28:43
Speaker 1: it suddenly stops and you just see a black hole? Right?
28:46
Speaker 1: Like would something like a star that's collapsing or something
28:50
Speaker 1: that's just stretching light. Wouldn't that make it more continuous? Right?
28:53
Speaker 1: Because the whole ring is kind of consistent with this
28:56
Speaker 1: idea that there's stuff, you know, orbiting around and then
28:58
Speaker 1: some of it falls in and then it has to disappear. Otherwise,
29:01
Speaker 1: where is it going? Why isn't it shining light? Even
29:04
Speaker 1: for a black hole? It's fairly continuous, right, Things get
29:07
Speaker 1: gradually redder and redder and more and more slow down
29:10
Speaker 1: before they fall in the event horizon. Even for a
29:12
Speaker 1: black hole, you never actually see something fall into the
29:15
Speaker 1: event horizon, unless, of course, there's something else coming behind
29:18
Speaker 1: it to pull the event horizon over it. So these
29:20
Speaker 1: scenarios actually look the same, right, having just a very
29:23
Speaker 1: intense gravitational source to gradually red shift and slow everything
29:27
Speaker 1: down as it falls in, or there being an actual
29:30
Speaker 1: event horizon beyond which things can't leave. Those two things
29:33
Speaker 1: actually do look the same from a distance. But wouldn't
29:37
Speaker 1: people have seen these maybe in the infrared, Like if
29:40
Speaker 1: we look out into the center of our galaxy, for example,
29:43
Speaker 1: with our infrared telescopes, wouldn't then we see a huge
29:46
Speaker 1: source of infrared light. Yeah, but the infrared radiation would
29:49
Speaker 1: be crazy long wavelengths. We're talking about like wavelengths the
29:52
Speaker 1: size of the galaxy, And we do not have sensors
29:55
Speaker 1: that can pick up infrared radiation at those frequencies, right,
29:58
Speaker 1: but we don't need We see it sort of ramp
29:59
Speaker 1: up towards the infrared spectrum. Yeah, but that would look
30:02
Speaker 1: the same for a black hole, right. A black hole
30:04
Speaker 1: would also show you more and more infrared as you
30:07
Speaker 1: get closer and closer to the event horizon because everything
30:10
Speaker 1: is getting red shifted, so they look the same from
30:12
Speaker 1: the outside because they have the same gravitational effect on
30:15
Speaker 1: things outside the event horizon. What are saying, there's no
30:19
Speaker 1: way to tell between a black hole and a not
30:22
Speaker 1: black hole. The only way to tell us to go
30:24
Speaker 1: visit close up, or to maybe sense things in the
30:27
Speaker 1: long infrared. Maybe if you had the ability to sense
30:30
Speaker 1: things in the very very far infrared, then something falling
30:32
Speaker 1: into a non black hole would continue to emit light
30:36
Speaker 1: that you would very faintly see in the very very
30:39
Speaker 1: long infrared, whereas things that fall actually past the event
30:42
Speaker 1: horizon of a black hole would stop emitting. Although you know,
30:45
Speaker 1: if you just drop a single object into a black hole,
30:48
Speaker 1: it's going to admit forever because it never actually falls
30:51
Speaker 1: past the event horizon, right, So it's really quite tricky.
30:54
Speaker 1: M all right, Well, I think what you're saying is
30:56
Speaker 1: that there's some doubt about whether even the images that
30:59
Speaker 1: we have of a black hole or even a black
31:01
Speaker 1: hole or represent the black hole, because there's a very
31:03
Speaker 1: technical definition about what counts as a black hole, that
31:06
Speaker 1: it's not just a big round circle in space. So
31:09
Speaker 1: if it's not a black hole, what could it be.
31:11
Speaker 1: So in a previous episode, we did talk about this
31:13
Speaker 1: idea of a collapsing star slowed down by a gravity
31:17
Speaker 1: that would look just like a black hole, and that's
31:19
Speaker 1: a really cool idea. But today we wanted to talk
31:21
Speaker 1: about a different idea because there are several ideas for
31:24
Speaker 1: what might be there that looks like a black hole
31:26
Speaker 1: but actually isn't. The idea here is to sort of
31:28
Speaker 1: take a neutron star and extended to a super duper
31:31
Speaker 1: neutron star. A fuzzball is like a very very dense
31:36
Speaker 1: state of matter where matters condensed even beyond the ability
31:39
Speaker 1: of a neutron star, but not quite to a black hole. Right,
31:43
Speaker 1: we talked about neutron stars, which are like the densest
31:47
Speaker 1: things in the universe, right before you might get to
31:49
Speaker 1: a black hole. Maybe recap for us what a neutron
31:52
Speaker 1: star is and how they occur. Yeah, so gravity is
31:54
Speaker 1: pulling everything together, right, It's gathering gas and dust to
31:57
Speaker 1: form stars, and the only way to stop gravity is
32:00
Speaker 1: to push back in some way. Our Sun has massive gravity,
32:04
Speaker 1: but it doesn't collapse because it's pushing out with its
32:06
Speaker 1: nuclear fusion. Creating a lot of energy and radiation pushing back.
32:10
Speaker 1: When that ends, though, when the Sun runs out of
32:12
Speaker 1: fuel or gets too cool because it's made too many metals,
32:15
Speaker 1: then it collapses even further. But there are other ways
32:18
Speaker 1: to resist gravity. You can have, for example, a white
32:20
Speaker 1: dwarf where matter is compressed really really intensely, but it's
32:23
Speaker 1: pushing back because the electrons and the atoms don't like
32:26
Speaker 1: to overlap. That can resist gravity. Or you can compress
32:29
Speaker 1: it even further so that you squeeze all those electrons
32:33
Speaker 1: inside the nucleus where they meet up with protons and
32:36
Speaker 1: convert into neutrons. So now you get a very very
32:39
Speaker 1: dense object which is essentially just a huge blob of
32:42
Speaker 1: neutrons all squeezed together. Right, because neutrons are neutral, so
32:47
Speaker 1: I guess they don't repel each other kind of right,
32:49
Speaker 1: So they're pretty happy, I guess, to be in that
32:51
Speaker 1: super duper dense state. Yeah, though they do feel the
32:54
Speaker 1: strong force and the quarks that are inside the neutrons
32:57
Speaker 1: push against each other, and so it resists the compress
33:00
Speaker 1: shouldn due to gravity, and it wants to stay as
33:02
Speaker 1: a neutron. Though we don't know what's going on at
33:04
Speaker 1: the very very heart of the neutron stars, where the
33:07
Speaker 1: pressure and the density against even crazier we talked about
33:10
Speaker 1: in the podcast, it might form weird states of matter
33:12
Speaker 1: like cork, gluon plasmas, or nuclear pasta. The point is
33:16
Speaker 1: that you still have objects, You still have matters, still
33:19
Speaker 1: resisting the compression of gravity. You probably have those fundamental particles,
33:24
Speaker 1: the quarks and gluons, swimming around at the heart of
33:26
Speaker 1: a neutron star. And that we thought was sort of
33:29
Speaker 1: the last defense of matter against gravity. That if you
33:32
Speaker 1: made a neutron star heavier more than like maybe two
33:35
Speaker 1: or three times the mass of our Sun, that it
33:37
Speaker 1: could no longer resist the compression of gravity and it
33:39
Speaker 1: would collapse to a black hole. A fuzz ball is saying, wait,
33:42
Speaker 1: maybe there's one more like interior fortress. Maybe there's one
33:46
Speaker 1: more way to resist that collapse. Maybe the things that
33:49
Speaker 1: are inside corks and gluons can do their own thing
33:53
Speaker 1: and form a new state of matter to resist gravity.
33:56
Speaker 1: M Right, Well, first of all, I guess, can a
33:59
Speaker 1: neutron star see what's inside of what we think is
34:02
Speaker 1: a black hole? Like can a neutron star trap light
34:05
Speaker 1: or at least slow it down enough that it looks
34:07
Speaker 1: like a whole. Neutron stars are very dense gravitationally, and
34:11
Speaker 1: so they definitely have these kinds of effects on light,
34:14
Speaker 1: but they're not massive enough to create a black spot
34:17
Speaker 1: in space. We can see neutron stars. We can even
34:20
Speaker 1: image X rays from hot spots on their surfaces and
34:23
Speaker 1: see them spinning, So we know the neutron stars are there.
34:26
Speaker 1: They're hard to spot because they don't go very much
34:28
Speaker 1: in the visible but we have seen them. We know
34:31
Speaker 1: that they're there, and that they do not have an
34:32
Speaker 1: event horizon, not even like a soft event horizon or
34:36
Speaker 1: like what sort of looks like to the visible eye
34:38
Speaker 1: like an event horizon. But they're also bending light to right,
34:41
Speaker 1: and they're also sort of, if not trapping, then slowing
34:44
Speaker 1: light down enough so that it looks black to us.
34:47
Speaker 1: They're definitely slowing down time, and they're definitely red shifting
34:51
Speaker 1: light because of their gravity, but they do not have
34:53
Speaker 1: an event horizon. We can see emissions directly from neutron
34:56
Speaker 1: stars absolutely, all right. So then inside of an image
34:59
Speaker 1: of the black hole, it's definitely not a neutron star.
35:01
Speaker 1: So you're saying, maybe a neutron star. There's a one
35:04
Speaker 1: thing it can turn into that would look like a
35:07
Speaker 1: black hole, but that is not a black hole. Exactly.
35:09
Speaker 1: As you add more mass to a neutron star, then
35:12
Speaker 1: the gravity gets stronger and stronger, maybe so strong that
35:15
Speaker 1: the corks and gluons now crack open. Our experiments can't
35:18
Speaker 1: see what's inside quarks and gluons. We don't know if
35:21
Speaker 1: there is anything inside them at all, and if that
35:23
Speaker 1: is what it is. We have several candidate theories, but
35:26
Speaker 1: it's all basically just mathematical speculation. We know corks and
35:29
Speaker 1: gluons are real, we don't know what's inside them. But
35:33
Speaker 1: if corks and gluons are made out of these things
35:36
Speaker 1: called strings, out of string theory, that it might be
35:39
Speaker 1: possible when you make that neutron star more massive than
35:42
Speaker 1: instead of collapsing all the way to a black hole,
35:44
Speaker 1: that those strings come out of the corks and gluons
35:47
Speaker 1: and do their own weird dance to create this bizarre
35:50
Speaker 1: object called a fuzz ball, which would be capable of
35:54
Speaker 1: resisting gravitational collapse. M I see. So like if you
35:57
Speaker 1: take a neutron star add more mass to it, into
36:00
Speaker 1: the gravity is so great it cracks open the corks
36:03
Speaker 1: and the strong force that's holding them together and sort
36:06
Speaker 1: of apart. And once you crack those open, maybe there
36:09
Speaker 1: are strings that then stay whole. They don't collapse into
36:13
Speaker 1: a black hole because there might be some string force.
36:16
Speaker 1: I guess it's keeping them from collapsing into a black hole.
36:18
Speaker 1: Exactly is there is something inside corks and gluons and
36:22
Speaker 1: it's held together with some force we don't know yet,
36:24
Speaker 1: Not the strong force that's the one that holds corks
36:26
Speaker 1: and gluons together to each other. But whatever is inside
36:29
Speaker 1: corks and gluons is being held together with some other
36:32
Speaker 1: force we haven't yet discovered. The string force, not the
36:35
Speaker 1: strong force, the string force. What's stronger the string force
36:38
Speaker 1: or the strong force? What stringing here? The string force
36:40
Speaker 1: or the strong force. It's a mess. Maybe it's the
36:43
Speaker 1: strange force. Maybe to pick another vowel, you know, the
36:45
Speaker 1: string force stirm and dring, the strong force, the strong
36:50
Speaker 1: strong force. There you go, Well, whatever is inside corks
36:54
Speaker 1: and gluons, if there is something inside there would have
36:56
Speaker 1: some force and you have to overcome that to crack
36:59
Speaker 1: it open. And yeah, maybe those would be strings, and
37:02
Speaker 1: those strings interact in ways that we don't even really
37:04
Speaker 1: fully understand because string theory math is very very hard
37:08
Speaker 1: to do, very complicated. But the idea is that if
37:11
Speaker 1: you squeeze a bunch of these strings close enough together,
37:14
Speaker 1: then they might tie themselves into these really weird, very
37:17
Speaker 1: very long strings. Like strings. We think, if they do exist,
37:21
Speaker 1: that they're super duper small. They're like ten to the
37:23
Speaker 1: minus thirty five meters wide distance we call the plank length.
37:28
Speaker 1: But if you take a bunch of strings and you
37:29
Speaker 1: squeeze them together, we think they might loop up and
37:32
Speaker 1: form super duper big strings. Like as you squeeze them together,
37:36
Speaker 1: weirdly they get larger, right, like real string. Well, let's
37:40
Speaker 1: get into the details here of a string hoole. I
37:42
Speaker 1: guess you would have to change the name of it, right,
37:44
Speaker 1: Maybe fause ball is not the right name. Maybe it
37:46
Speaker 1: should be a string ball. So let's get into the
37:48
Speaker 1: details of that and whether or not we might ever
37:50
Speaker 1: be able to detect such a thing in space. But
37:53
Speaker 1: first let's take another quick break. I feel like you're
38:08
Speaker 1: stringing me along here, Daniel, to answer the question whether
38:11
Speaker 1: or not the black hole really exists or is what
38:14
Speaker 1: we think a black hole? What we think is an
38:16
Speaker 1: image of a black hole is actually an image of
38:18
Speaker 1: something else that is technically not a black hole, but
38:21
Speaker 1: maybe something called a string ball. Well, the Adventures of
38:25
Speaker 1: It could have called it a string ball, but they
38:27
Speaker 1: decided to go with a fuzz ball instead, right, even
38:30
Speaker 1: though string ball would be more accurate, wouldn't it. I
38:32
Speaker 1: don't know the images I've seen online that describe what
38:35
Speaker 1: these scientists are thinking about. It looks pretty fuzzy, so
38:38
Speaker 1: you know, I like buzz ball. Well, I think the
38:40
Speaker 1: idea is that if you take a neutron star, which
38:42
Speaker 1: is a super duper heavy object, and then you squeeze
38:46
Speaker 1: it even more, you break open the neutrons and the corks,
38:49
Speaker 1: and you spill out all the strings that might be
38:51
Speaker 1: inside of a cork, and then you make a ball
38:54
Speaker 1: out of those things before they actually collapse into an
38:58
Speaker 1: infinite singularity, which is but would be a black hole exactly,
39:02
Speaker 1: these things would resist collapse because of their stringiness. And also,
39:06
Speaker 1: really interestingly, strings themselves can't be part of a singularity
39:10
Speaker 1: because they have an extent, right, they have a minimum size.
39:14
Speaker 1: Strings are not point objects the way electrons are or
39:17
Speaker 1: quarks are in our current theory or in any theory
39:20
Speaker 1: of fundamental particles. Strings themselves have a minimum size there
39:24
Speaker 1: are quantum object so they can never have infinite density,
39:27
Speaker 1: which is sort of cool. Even if you had a
39:28
Speaker 1: single string, right, it's not a singularity. And here you
39:31
Speaker 1: take a bunch of strings, you put them together into
39:34
Speaker 1: a string ball or a buzz ball, whatever you want
39:36
Speaker 1: to call it, and it's actually quite big and quite massive.
39:39
Speaker 1: So this thing would be like a huge object. But
39:42
Speaker 1: it's also like made out of this weird fundamentally quantum
39:46
Speaker 1: thing a string. So you know, the sort of the
39:49
Speaker 1: way like a Bose Einstein condensate is a macroscopic object
39:52
Speaker 1: that obeys quantum properties. This thing also would be like
39:55
Speaker 1: a really big, huge macroscopic object that shows it's stringing nature.
40:01
Speaker 1: M So it'd be made out of strings. And you
40:03
Speaker 1: said that the strings would tie themselves together or you know,
40:06
Speaker 1: sort of become longer strands of strings. Strings when you
40:09
Speaker 1: combine them, their tension actually decreases, right, So as you
40:13
Speaker 1: put more strings together, the tension decreases as they get
40:17
Speaker 1: longer and longer. So are similar to like a guitar string, right,
40:20
Speaker 1: A guitar string that you shorten has a higher tension
40:23
Speaker 1: and makes a higher sound, whereas if you let your
40:26
Speaker 1: guitar string get longer than it makes a deeper sound. Right,
40:28
Speaker 1: And that's how it works on the fretboard, right, you're
40:30
Speaker 1: shortening the length of the string, you're increasing the tension,
40:33
Speaker 1: so you're increasing the frequency. The same thing happens for
40:35
Speaker 1: these kinds of strings. As you tie a bunch of
40:38
Speaker 1: them together, they tend to get longer and the tension decreases.
40:41
Speaker 1: And so if you can squeeze a bunch of strings together,
40:43
Speaker 1: they can make really big macroscopic objects like a fuzzball,
40:47
Speaker 1: sort of like a new state of matter. You can
40:50
Speaker 1: imagine it as all right, So then I guess you
40:53
Speaker 1: can compact all that mass even more, so you get
40:56
Speaker 1: even more intense density and even more bending at space.
40:59
Speaker 1: Would you then be able to trap light? Yeah, fuzzball
41:03
Speaker 1: has so much gravity in such a tiny spot that
41:06
Speaker 1: from the outside it looks like a black hole, right,
41:09
Speaker 1: the same way a dark star does. You don't actually
41:12
Speaker 1: have to have a singularity in order to bend space
41:15
Speaker 1: enough to create gravitational redshifting and time dilation to look
41:20
Speaker 1: like a black hole, or to be indistinguishable with our
41:23
Speaker 1: technology from a true general relativistic black hole, so it
41:26
Speaker 1: would have an event horizon. It doesn't have an event horizon, right,
41:30
Speaker 1: like a black hole, there is no event horizon there.
41:32
Speaker 1: But it does distort light in the same way a
41:34
Speaker 1: dark star wood. It makes the frequencies very very long,
41:38
Speaker 1: very red, and it slows everything down. Wait, why wouldn't
41:42
Speaker 1: it have an event horizon. Couldn't you imagine putting so
41:44
Speaker 1: many strengths in one spot that it would create an
41:47
Speaker 1: event horizon. You could, But this thing resists collapse to
41:50
Speaker 1: that density because the strings have the sort of like
41:53
Speaker 1: outward pressure like puff up, providing enough outward pressure to
41:57
Speaker 1: avoid collapsing to that density. But that's only as ming
42:00
Speaker 1: SEMs that the force that keeps them together is strong
42:03
Speaker 1: enough to prevent the event horizon from forming. But couldn't
42:06
Speaker 1: you also imagine a string ball where the force is
42:09
Speaker 1: strong enough not to create a singularity, but maybe strong
42:12
Speaker 1: enough to create an event horizon. In principle, what you're
42:14
Speaker 1: describing is like a quantum mechanical black hole, where you
42:17
Speaker 1: have enough mass within like the short styles radius to
42:19
Speaker 1: create an event horizon. That is technically possible if you
42:23
Speaker 1: can get some matter to that density This is the
42:25
Speaker 1: suggestion that strings are preventing the matter from getting to
42:29
Speaker 1: that density, so there is no event horizon there. You're
42:32
Speaker 1: right that if in principle, you could squeeze the strings
42:35
Speaker 1: down even further, you could satisfy that condition and create
42:38
Speaker 1: a classical black hole. But the calculations here suggest as
42:41
Speaker 1: strings are puffy enough that they resist compression, so they
42:44
Speaker 1: don't actually form a black hole. That's what makes this
42:47
Speaker 1: different from a black hole. There's no event horizon here,
42:50
Speaker 1: right right, We're not asking the question like how can
42:52
Speaker 1: you make a black hole without a singularity. We're asking
42:55
Speaker 1: the question, can you create something that looks like a
42:57
Speaker 1: black hole that wouldn't turn into a black hole? Exactly?
43:00
Speaker 1: Is there another step between neutron star and actual density
43:03
Speaker 1: of objects that create an event horizon? And this suggestion
43:06
Speaker 1: from string theory is that you can form this new
43:09
Speaker 1: state of matter called a fuzzball, which is not dense
43:11
Speaker 1: enough to create an event horizon, but sort of looks
43:14
Speaker 1: a lot like an event horizon to our technological eyeballs.
43:17
Speaker 1: Right because before the only step we knew was a
43:20
Speaker 1: neutron star, and we know that a neutron star wouldn't
43:22
Speaker 1: look like a black hole. But maybe because we know
43:25
Speaker 1: enough about the strong force, I guess to make that call.
43:28
Speaker 1: But maybe there's something that neutron star would collapse to
43:31
Speaker 1: that wouldn't be a true black hole. Yeah, exactly, you
43:33
Speaker 1: add mass to a neutron star, maybe there's another step
43:36
Speaker 1: there before it collapses to the density you need to
43:38
Speaker 1: create an event horizon. But from a distance, this thing
43:41
Speaker 1: is so close to an official black hole in terms
43:43
Speaker 1: of density that it acts almost like one. It's indistinguishable
43:47
Speaker 1: using our sensors from an actual black hole with the
43:49
Speaker 1: real event horizon, right, would be more like a black
43:52
Speaker 1: divid like vivid sort of looks like a hole from
43:54
Speaker 1: a certain press practice because there is it's trapping some things,
43:58
Speaker 1: but it's not actually a whole. Yeah, or maybe it's
44:00
Speaker 1: like an off black hole. Right, it's not black. If
44:04
Speaker 1: you look at really really carefully with the right instrument,
44:07
Speaker 1: you might detect some radiation, right, Yeah, But I think
44:10
Speaker 1: what it would sort of pretty much act like a
44:12
Speaker 1: black hole, like if you get near it, it would
44:13
Speaker 1: spaghettify you perhaps, right. Absolutely, gravity from a distance is
44:18
Speaker 1: the same as from any object of that mass, And
44:20
Speaker 1: because it is really really dense, you could get close
44:23
Speaker 1: enough for the tidal forces to be very dramatic. Right,
44:25
Speaker 1: And it would also form the rings around itself. Right, Yeah,
44:29
Speaker 1: it would form an acretion disk exactly. Just that. The
44:31
Speaker 1: difference is that it doesn't create an event horizon exactly.
44:33
Speaker 1: That's the difference. And it's not just speculation. These guys
44:36
Speaker 1: have done these calculations in string theory and suggested that
44:39
Speaker 1: this thing could actually form. That's really as possible for
44:42
Speaker 1: strings to create this state of matter. It's not just like, hey,
44:45
Speaker 1: maybe there's some state of matter. It actually does come
44:48
Speaker 1: from the calculations of how we think strings would behave
44:51
Speaker 1: if they were real. Right. But strength theories totally made up,
44:54
Speaker 1: so you know, it's the same thing. And if you
44:58
Speaker 1: make something up, if you prove something with a made theory,
45:00
Speaker 1: it's still made up, isn't it. It is still made
45:02
Speaker 1: up in this case, though it does match everything we
45:04
Speaker 1: see in the universe. Right. They basically give the same
45:07
Speaker 1: predictions for the observations as the classical general relativistic black hole.
45:11
Speaker 1: And it solves the quantum mechanics problem because these things
45:14
Speaker 1: do not create singularities that violate quantum mechanics. They are
45:18
Speaker 1: actual quantum mechanical objects. Plus they solve a bunch of
45:21
Speaker 1: other problems related to black holes, so theoretically they are
45:24
Speaker 1: very attractive for those reasons. Although you're right, we can't
45:27
Speaker 1: tell the difference between a black hole and a string
45:30
Speaker 1: ball or a fuzz ball, and so from that sense,
45:33
Speaker 1: it is just still made up, right. And also you've
45:35
Speaker 1: got to ask the question, like what happens if you
45:37
Speaker 1: do have a string ball and you put more strings
45:39
Speaker 1: into it? Is it eventually going to collapse into a
45:41
Speaker 1: black hole? Or are they saying that string balls can
45:43
Speaker 1: never become black holes? These would never become black holes
45:46
Speaker 1: because as you add more strings, they get larger and larger,
45:50
Speaker 1: so they don't get denser. Tension on the strings actually
45:52
Speaker 1: get smaller as they get larger. So as you add
45:56
Speaker 1: more and more strings, you just get a bigger string ball.
45:59
Speaker 1: M hm. So you ever increase the density, that's what
46:01
Speaker 1: you're saying. Yeah, the density never crosses that threshold. But
46:04
Speaker 1: if the force relaxes, wouldn't you be able to compress
46:07
Speaker 1: them more more stuff? You mean, like the force just
46:09
Speaker 1: took a vacation. It's like, hey, it's Friday, I'm tired
46:12
Speaker 1: of holding the string ball up yeah, pasically right, Like,
46:15
Speaker 1: if he's saying that the strings get more relaxed, wouldn't
46:17
Speaker 1: you be able to slip in more smaller strings in there?
46:20
Speaker 1: The strings getting more relaxed means length goes up, right,
46:23
Speaker 1: because the tension and the length are inversely proportional. That's
46:26
Speaker 1: why these things get bigger and bigger. So maybe in
46:28
Speaker 1: some versions of string theory these things wouldn't be allowed.
46:31
Speaker 1: But in the calculations that these folks have done, they
46:34
Speaker 1: suggested these things would never collapse to have an object
46:37
Speaker 1: with an event horizon. All right, So then this is
46:40
Speaker 1: an idea that maybe says that the things that we
46:43
Speaker 1: think are black holes are actually not black holes. Although
46:45
Speaker 1: even if these things do exist, would that make black
46:48
Speaker 1: holes impossible or just not likely? These would make black
46:52
Speaker 1: holes impossible at least out of matter that is made
46:54
Speaker 1: of strings. Couldn't I smash two strings together, a bunch
46:57
Speaker 1: of strings together, so fast and so hard that they
47:00
Speaker 1: form a real black hole. You know, that's a great
47:02
Speaker 1: question if temporarily you could overcome this stringy puffinus to
47:07
Speaker 1: create that density. I don't know the answer to that,
47:09
Speaker 1: and I don't know if anybody does, Because you know,
47:11
Speaker 1: these calculations are very very hard to do. String theory
47:14
Speaker 1: is very complex. These calculations are done in like eleven
47:17
Speaker 1: or twenty six dimensions because that's the space in which
47:20
Speaker 1: strings work. And so I don't think anybody knows the
47:22
Speaker 1: answer what would happen if you collided to string balls?
47:25
Speaker 1: Let's do it. But I feel like it's convenient that
47:29
Speaker 1: made up theory is so complex you can actually do
47:32
Speaker 1: a lot of calculations in it. You know, the people
47:34
Speaker 1: who do string theories say it's beautiful and it's wonderful.
47:37
Speaker 1: I've never done any string theory calculations myself, so I
47:39
Speaker 1: can't attest to that. But it is very complicated, as
47:41
Speaker 1: only a few people in the world who know how
47:43
Speaker 1: to do string theory calculations. And also we should say
47:46
Speaker 1: that they haven't done the full calculation here. They've taken
47:49
Speaker 1: like a lot of simplifications and they've solved it in
47:51
Speaker 1: like a few different cases that are related to our universe,
47:55
Speaker 1: but not exactly our universe. So they sort of suggestive calculations,
47:59
Speaker 1: not like really conclusive results. Interesting, well, we might need
48:03
Speaker 1: to change the name of black holes to spring balls
48:06
Speaker 1: or or fuzzballs, and this is also convenient like this
48:10
Speaker 1: idea of a fuzz ball or a string ball is
48:12
Speaker 1: interesting too because you said it solves other inconsistencies about
48:16
Speaker 1: real black holes. Classical black holes, the ones imagined by
48:19
Speaker 1: Einstein's theory of relativity, have a lot of problems with
48:22
Speaker 1: quantum mechanics, but they also have problems with information. You know.
48:25
Speaker 1: One problem is that things are falling into the black hole,
48:29
Speaker 1: and a classical black hole just sort of eats them.
48:31
Speaker 1: But we know that black holes eventually will evaporate. They
48:34
Speaker 1: admit this faint radiation at their edges called Hawking radiation,
48:38
Speaker 1: and so they disappear, and so in our universe that
48:40
Speaker 1: means that the information falls into a black hole and
48:43
Speaker 1: then is gone. We had a fun episode about the
48:45
Speaker 1: black hole information paradox, so check that out. But this
48:48
Speaker 1: is a real problem with the sort of the structure
48:50
Speaker 1: of classical black holes. What happens to information that falls
48:53
Speaker 1: inside of them? And so this solves them because there
48:56
Speaker 1: is no event horizon, and so nothing falls past the
48:59
Speaker 1: event horizon and disappears. So it sort of solves that
49:02
Speaker 1: problem by deleting it from the universe. M I see,
49:05
Speaker 1: if there is no event horizon, then there's no problem
49:08
Speaker 1: with an event horizon. Basically, stuff that you throw into
49:11
Speaker 1: the string ball just becomes more strings, and this quantum
49:13
Speaker 1: information is not lost, is still there on the string ball,
49:17
Speaker 1: all right, And that would make more sense in the universe,
49:20
Speaker 1: or it would just be more more easier to study,
49:24
Speaker 1: that would make more sense. Quantum mechanics says that information
49:27
Speaker 1: cannot be lost, that everything you do imprints itself on
49:30
Speaker 1: the future of the universe, and then in principle, you
49:34
Speaker 1: could reverse engineering to find out exactly what happened in
49:36
Speaker 1: the past. It's very deep principle in quantum mechanics. And
49:39
Speaker 1: if that is wrong, then like everything we think we
49:41
Speaker 1: understood abou quantum mechanics is wrong. So according to our
49:44
Speaker 1: current theories, information should not be lost in the universe,
49:47
Speaker 1: and yet classical black holes do seem to delete it.
49:50
Speaker 1: So this would nicely avert that problem, all right. Well,
49:53
Speaker 1: it sounds like every time you look at an image
49:55
Speaker 1: of a black hole, you should, in the back of
49:57
Speaker 1: your mind think, maybe it's not a black hole, maybe
50:00
Speaker 1: it's a string ball. And you know, science is a process.
50:03
Speaker 1: We start out with an idea and we get closer
50:05
Speaker 1: and closer to the truth. But you always have to
50:07
Speaker 1: keep in the back of your mind, what do we
50:08
Speaker 1: actually know? Have we really verified this? Is there a
50:12
Speaker 1: possibility for it to be something else, something other than
50:15
Speaker 1: the current theoretical idea, And so it's exciting to hear
50:19
Speaker 1: people thinking about what else black holes might be that
50:22
Speaker 1: would still look like the black holes we think we
50:25
Speaker 1: see out there in the universe. Right. Yeah, it's good
50:28
Speaker 1: to remember that this idea of a fastball is really
50:30
Speaker 1: just a theory, right, and in fact based on strength theory,
50:33
Speaker 1: which is sort of not like a real theory, It's
50:34
Speaker 1: more like a like a pet theory, right, more like
50:37
Speaker 1: a pepito theory. I do like to scratch the heads
50:40
Speaker 1: of string theories whenever I see them, just to give
50:42
Speaker 1: them some encouragement. That sounds really inappropriate, Daniel, Do you
50:46
Speaker 1: get consent before he's crashed their heads? They tend to purr.
50:48
Speaker 1: So what can I say? But yes, string theory is
50:51
Speaker 1: a speculative theory of what might be happening inside particles,
50:54
Speaker 1: and it makes this really fun prediction or what happens
50:57
Speaker 1: if you get like the mass of the sun in
50:58
Speaker 1: terms of strings and lease them all together. So it's
51:01
Speaker 1: a really fun prediction that would solve a bunch of
51:03
Speaker 1: problems and also be kind of awesome to think about. Yeah,
51:06
Speaker 1: at least in some universe, my not br universe, in
51:09
Speaker 1: some universe. Alright, Well, we hope you enjoyed that. Thanks
51:12
Speaker 1: for joining us, see you next time. Thanks for listening,
51:22
Speaker 1: and remember that Daniel and Jorge explained. The Universe is
51:25
Speaker 1: a production of I Heart Radio. For more podcast for
51:29
Speaker 1: my heart Radio, visit the i heart Radio app, Apple Podcasts,
51:33
Speaker 1: or wherever you listen to your favorite shows.