Latest / Daniel and Kelly’s Extraordinary Universe / Can we put black holes to work for us?

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Can we put black holes to work for us? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, when is all this physics research going to
0:11
Speaker 1: pay off? Payoff? What do you mean did you invest
0:14
Speaker 1: in some exo planet startup kind of like with my taxes? Right?
0:18
Speaker 1: Isn't all of physics research funded by the public. I
0:20
Speaker 1: guess that's true. But isn't the sheer pleasure of learning
0:23
Speaker 1: about the universe enough for you? Like you want some
0:26
Speaker 1: cash out? Also, it's not enough for my bank account.
0:29
Speaker 1: That's fresh. But you know, I'd be nice to get
0:31
Speaker 1: at least some nice invengors out of it. You know,
0:33
Speaker 1: I think everyone is still waiting for the teleporting machine,
0:35
Speaker 1: or the backpacks or the warp drive. Well I might
0:38
Speaker 1: be able to offer you a pasta maker. Is it
0:40
Speaker 1: a warp pasta maker? No, but it's a black hole
0:43
Speaker 1: powered spaghettification machine. What what's the plane? Are were going
0:48
Speaker 1: to open an Italian restaurant next to a black hole? Yeah? Exactly,
0:51
Speaker 1: fresh black hole pasta delivered in a thousand years. You're
0:54
Speaker 1: getting not tipped from me if it takes a thousand
0:56
Speaker 1: years to get my dinner darker than a squid. Inc
0:59
Speaker 1: Is it fusion? For see or inguinilla physicists? It must
1:03
Speaker 1: be or zoes because their length contracted or is the
1:05
Speaker 1: little grain ones? Hi am more handmade cartoonists and the
1:23
Speaker 1: creator of PhD comics. Hi, I'm Daniel. I'm a particle
1:26
Speaker 1: physicist and a professor a UC Irvine and I do
1:30
Speaker 1: make homemade pasta. Oh you do? Do you make each
1:33
Speaker 1: noodle individually or do you have one of those machines?
1:37
Speaker 1: I sculpt them by hand. Each one is a work
1:39
Speaker 1: of art. I give them a name. I meant an
1:41
Speaker 1: n F T for each one I see. And then
1:44
Speaker 1: everyone just gets one piece of pasta for dinner, one
1:48
Speaker 1: big pasta, exactly pasta, and they're called one giant too.
1:52
Speaker 1: Do you just set it down in the middle of
1:53
Speaker 1: the dinner table? Sit here? That's right, exactly, Technically it's pasta. No,
1:58
Speaker 1: we use a pasta machine and so we slice it
2:00
Speaker 1: up into spaghetti or linguini or one of the other nies. Yeah,
2:04
Speaker 1: we have one of those in our house and we've
2:06
Speaker 1: used it a few times. But it's a lot of work.
2:07
Speaker 1: It absolutely is a lot of work, but there's also
2:10
Speaker 1: something fun about it. You get your kitchen all flowery
2:12
Speaker 1: and your pants all covering flower At the end, you
2:14
Speaker 1: get something which tastes a little bit better than something
2:17
Speaker 1: you can buy in the store, a little bit better.
2:19
Speaker 1: I guess it might be worth it that. But welcome
2:21
Speaker 1: to our podcast, Daniel and Jorge Explain the Universe, a
2:23
Speaker 1: production of I Heart Radio in which we turn your
2:26
Speaker 1: brain into spaghetti by exploring all of the mysteries of
2:29
Speaker 1: the universe, everything that's out there that makes sense to us,
2:32
Speaker 1: and everything that's out there that doesn't yet make sense.
2:35
Speaker 1: We talk about the tiniest little particles buzzing around in
2:38
Speaker 1: your toenail, all the way up to supermassive black holes
2:42
Speaker 1: anchoring enormous galaxies billions of years away. We don't shy
2:45
Speaker 1: away from the biggest, deepest, darkest, craziest, most bonker's question,
2:49
Speaker 1: because we want to introduce you to the craziness that
2:52
Speaker 1: is this universe. That's right. We take all of that
2:55
Speaker 1: amazing resource that physicists and scientists are doing at the
2:58
Speaker 1: edge of human knowledge. We take that and we boil
3:00
Speaker 1: it for a really long time until it's soft and
3:03
Speaker 1: soggy enough for people to consume. No, we stop at
3:06
Speaker 1: just the right moment so we can serve up the
3:08
Speaker 1: information all dente. We like it a little bit of crunch.
3:11
Speaker 1: Your kids like it with a little bit of crunch.
3:13
Speaker 1: Mine like it's super soggy. Yeah, no, mine like it overcooked.
3:16
Speaker 1: They even call it overcooked. They're like, make sure to
3:18
Speaker 1: make it overcooked. Make sure you overcook it. And then
3:22
Speaker 1: we sprinkle it with a little bit of olive oil, right,
3:24
Speaker 1: and that jokes exactly. Do you like your pasta with bananas? Well,
3:27
Speaker 1: that's how we're serving it today. Oh man, we just
3:31
Speaker 1: invented a new recipe, banana marinara. That's just fun to
3:34
Speaker 1: say a and b intriguingly tasty. Perhaps maybe, I don't know,
3:39
Speaker 1: maybe more controversial than pineapple on pizza is banana on pasta.
3:43
Speaker 1: It's a slippery slope once you start putting fruit into
3:46
Speaker 1: it telling food, especially if the banana peels are all
3:49
Speaker 1: over the floor, then it's definitely a slippery slope. Yeah.
3:51
Speaker 1: So we like to talk about science and all of
3:53
Speaker 1: the amazing things that people are out there discovering and
3:55
Speaker 1: all of the big mysteries, all the things we don't
3:58
Speaker 1: know about the universe, every thing that physicists are in
4:01
Speaker 1: their offices and labs thinking about and pondering about that
4:04
Speaker 1: maybe one day will be something that everybody knows. That's right,
4:07
Speaker 1: and there's a variety of motivations for digging into the
4:11
Speaker 1: mysteries of the universe. Some of us just want to know,
4:14
Speaker 1: are driven by the insatiable curiosity to understand the universe.
4:18
Speaker 1: See it as a giant puzzle, a mystery posed for
4:22
Speaker 1: humanity that we need to unravel, no matter how many
4:25
Speaker 1: millennia takes to gain that understanding of the universe. But others,
4:28
Speaker 1: the more practical minded folks among us, might be interested
4:32
Speaker 1: in figuring out how the universe works to better our lives,
4:35
Speaker 1: to figure out how to put it to work for us,
4:38
Speaker 1: to take advantage of that knowledge to deliver inventions to humanity. Yeah,
4:42
Speaker 1: because that's what the universe is there for. Right, It's
4:44
Speaker 1: there for us. It's the whole reason it's there, is
4:47
Speaker 1: just to make our lives easier and more exciting. I suppose. Maybe,
4:51
Speaker 1: I mean it could be there for the aliens, right,
4:53
Speaker 1: maybe we're just part of the aliens universe. Wait, what
4:57
Speaker 1: we're there for the aliens? Hopefully not for dinner. Maybe
5:02
Speaker 1: maybe we're just here to be a plot twist in
5:04
Speaker 1: some drama that's been going on for thousands of years
5:06
Speaker 1: over on Proximus Centauri. You know, well, I see, we're
5:10
Speaker 1: just like an adjacent to an event or Avengers movie
5:13
Speaker 1: or something exactly. You thought you were going to be
5:14
Speaker 1: part of the main cast. It turns out you only
5:16
Speaker 1: got a few lines. You won't get your own Marvel
5:18
Speaker 1: movie for another trillion years. Perhaps they'll eventually make a
5:22
Speaker 1: Marvel movie out of every single person in the Marvel
5:25
Speaker 1: University plant. It will be the ultimate crossover, you know,
5:28
Speaker 1: it will just be called not the Marvel Universe, just
5:31
Speaker 1: the universe. Well, regardless of why the universe exists, of
5:36
Speaker 1: question we may never know the answer to. It is
5:39
Speaker 1: interesting to think about how we can put the universe
5:41
Speaker 1: to work for us, because sometimes the knowledge of physics
5:44
Speaker 1: extracts does have practical value. Yeah, I mean, we have
5:48
Speaker 1: nuclear fission right, powering most of Europe, I think, and
5:52
Speaker 1: a lot of the United States and around the world.
5:54
Speaker 1: That was all physics, right, That was all physics, the
5:57
Speaker 1: good and the bad. We also have nuclear weapons into
6:00
Speaker 1: that civilian populations and used for political ends. But you know,
6:03
Speaker 1: there's two sides to every corn. Yeah, that's right, it's
6:08
Speaker 1: all your fault. But even our everyday sort of inventions
6:11
Speaker 1: that we use every day in our cell phones, have
6:14
Speaker 1: you know physics stuff in it that we learned, maybe
6:16
Speaker 1: not the cutting edge stuff now, but stuff that was
6:18
Speaker 1: cutting edge a long time ago. You know, all those
6:20
Speaker 1: tiny little circuits and how they work down at the
6:22
Speaker 1: atomic level. We needed to understand how to make those things.
6:26
Speaker 1: That's right. Essentially, the nature of your life today, the
6:28
Speaker 1: way you live your day is the way it is
6:31
Speaker 1: because we understood quantum mechanics that lead to revolutions in
6:35
Speaker 1: computing and therefore electronics and your life. And so it's
6:39
Speaker 1: true that basic research, digging into the nature of space
6:43
Speaker 1: and time and forces eventually gives us the power to
6:46
Speaker 1: change our lives. You know, it's a song I've lung
6:49
Speaker 1: many times on this podcast. I don't understand why politicians
6:52
Speaker 1: don't just invest more in basic research, because it pays
6:55
Speaker 1: itself back a hundredfold. Every dollar you spend today gives
6:59
Speaker 1: your children and your grandchildren improved quality of life. I
7:02
Speaker 1: don't get it. Why do we don't invest in that more? Actually,
7:04
Speaker 1: that's kind of an interesting philosophical question, like do you
7:06
Speaker 1: think we could have invented the cell phone without knowing physics? Right?
7:10
Speaker 1: Like could we just have been tinkered and then done
7:13
Speaker 1: engineering just to get it to work and eventually gone
7:15
Speaker 1: on the cell phone without understanding quantum mechanics or fusion. Absolutely,
7:19
Speaker 1: I think, as from a philosophical point of view, it
7:22
Speaker 1: is possible to make technological advancements without understanding what you're doing.
7:28
Speaker 1: We have sort of like the invention of modern science,
7:31
Speaker 1: at least in the Western world, only like five years ago.
7:33
Speaker 1: This question is like trying to develop models that explain
7:36
Speaker 1: what we're seeing. But we definitely had technological advancement well
7:40
Speaker 1: before then. People have been forging very impressive like samurai
7:43
Speaker 1: swords for thousands of years without understanding, like what's going
7:47
Speaker 1: on with the metallurgy they were doing. Why are you
7:50
Speaker 1: dipping the sword in water now? And then you dip
7:52
Speaker 1: it in this other thing and you wait this number
7:53
Speaker 1: of seconds. You can sort of random walk your way
7:57
Speaker 1: into technology without understanding what's going on. Could you get
8:00
Speaker 1: all the way to the cell phone? You know, you
8:02
Speaker 1: give yourself off another thousand years or million years? Yeah? Maybe? Wait,
8:05
Speaker 1: so are you saying that we don't need physics, then
8:07
Speaker 1: I think that's what you just concluded. I think technically
8:09
Speaker 1: you don't need physics, but definitely it helps. It's super
8:12
Speaker 1: charges your technological advancements because you understand what's going on,
8:16
Speaker 1: then you can come up with new ideas for how
8:19
Speaker 1: to use them. You're like the little sprinkle of parsley
8:22
Speaker 1: at the top of the pasta. Is that what physics
8:25
Speaker 1: has been reduced to in this episode? I'd say you're
8:27
Speaker 1: the reason you're getting your pasta in five minutes instead
8:29
Speaker 1: of in a million years. Oh, I see, I see,
8:32
Speaker 1: I see. That's you're the reason it's not stale and stiff.
8:35
Speaker 1: Right up, we're getting hot, fresh pasta because of physicists.
8:38
Speaker 1: That's right. I'll take credit for that hot fresh cell
8:40
Speaker 1: phones slurp it up. Would you like a little parsley
8:42
Speaker 1: on your cell phone? Having some bananas? Well, at least
8:46
Speaker 1: you can look at pictures of bananas and parsley in
8:48
Speaker 1: your cell phone now instead of in a thousand years,
8:51
Speaker 1: So that that's something. So that's something. Yeah, exactly, I'll
8:54
Speaker 1: put that on my CV. You can swipe left on
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Speaker 1: a banana and do all kinds of things with it.
9:00
Speaker 1: But yeah, it is a pretty amazing universe, and sometimes
9:02
Speaker 1: we wonder if we can put more of it to
9:04
Speaker 1: work for us, especially the things out there that are
9:07
Speaker 1: amazing and seemingly super amazingly incredibly powerful exactly because we
9:12
Speaker 1: are struggling constantly as a species to extract enough energy
9:16
Speaker 1: for our survival. At the same time, we are surrounded
9:19
Speaker 1: by intensely powerful astrophysical objects. The Son, of course is
9:23
Speaker 1: a great example. We capture a tiny little bit of
9:26
Speaker 1: its energy, and they're even more powerful, incredibly vast things
9:30
Speaker 1: out there that are like huge engines pumping out energy.
9:33
Speaker 1: Could we take advantage of some of these incredible astrophysical
9:36
Speaker 1: machines to gather some energy we need, you know, to
9:40
Speaker 1: charge our cell phones. So today on the podcast, we'll
9:42
Speaker 1: be asking the question can we put black holes to
9:50
Speaker 1: work for us? WHOA Daniel? I feel like this is
9:55
Speaker 1: going to that idea of putting an Italian restaurant next
9:57
Speaker 1: to a black hole and maybe having a black hole
9:59
Speaker 1: watched the dishes for us. Is that what you mean? Yeah,
10:01
Speaker 1: I'm just wondering when the black holes are going to unionize,
10:03
Speaker 1: you know, when they're gonna rise up against us, their oppressors,
10:07
Speaker 1: and be like, hey, these conditions are terrible and stuck
10:10
Speaker 1: out here in the middle of nowhere and we're just
10:11
Speaker 1: eating gas and dust all day interesting, and then they're
10:14
Speaker 1: going to change their name to red holes. You know,
10:19
Speaker 1: solidarity of communism. That's right, black holes of the universe unite.
10:24
Speaker 1: You have nothing to lose but your event horizons. That
10:27
Speaker 1: is their ultimate plan, isn't it all black holes? They
10:30
Speaker 1: just want to unite and get basically create one giant
10:35
Speaker 1: union or one giant black hole, one socialist black hole exactly.
10:38
Speaker 1: That's the future of the universe. This is a question
10:41
Speaker 1: by tapping into the power of these crazy objects, I
10:44
Speaker 1: mean the amount of light radiated from black holes, amount
10:47
Speaker 1: of gravitational energy stored in black holes, we are like
10:50
Speaker 1: sitting on the edge of an incredible river of energy
10:53
Speaker 1: and we're just really bad at tapping into it. We're
10:56
Speaker 1: like burning coal that we dig up from underground to
10:58
Speaker 1: get tiny little slipper of energy out. It's ridiculous. Yeah,
11:02
Speaker 1: there's a lot of amazing things happening in the universe,
11:04
Speaker 1: but you know, I would think that black holes would
11:06
Speaker 1: be sort of like the last place you go to
11:08
Speaker 1: to get energy or to get anything useful out of it,
11:11
Speaker 1: because you know, they're kind of in the name their
11:13
Speaker 1: their holes. It's like, why would you go to a
11:15
Speaker 1: hole to get something out of it? Maybe we could
11:19
Speaker 1: throw a trash into the black hole, so we wouldn't
11:22
Speaker 1: have to think about it. But it's kind of weird, right,
11:24
Speaker 1: because black holes suck everything in and once he gets
11:27
Speaker 1: sucked in, you can't get out, So it's kind of
11:28
Speaker 1: weird to think that you could use them for anything useful.
11:31
Speaker 1: That's true, but they are also really vast stores of energy.
11:35
Speaker 1: I mean, the reason that they are black holes is
11:37
Speaker 1: because they have so much mass in them, and that
11:40
Speaker 1: mass reflects internal store and energy. So you can think
11:42
Speaker 1: of a black hole like a giant cosmic battery. So
11:47
Speaker 1: much energy has been poured into it. It's just sitting there,
11:50
Speaker 1: compressed and dense and bubbling up. So it's tempting to think, like,
11:53
Speaker 1: can we tap into that a tiny little bit? But
11:55
Speaker 1: it's weird because we know nothing can ever get out
11:57
Speaker 1: of a black hole. That's true, we can to take
12:00
Speaker 1: anything out of a black hole. But remember the black
12:02
Speaker 1: holes have influence far beyond their event horizon. If you're
12:06
Speaker 1: anywhere near a black hole, they will tug on you
12:08
Speaker 1: the same way the sun does. And so the mass
12:11
Speaker 1: of the black hole, even though it's contained within the
12:13
Speaker 1: event horizon, can influence things outside the event horizon, and
12:18
Speaker 1: you can use that gravity to maybe charge your cell phone.
12:21
Speaker 1: I see, you just want to mooch off of their influence,
12:24
Speaker 1: all of their hard earn, you know, connections and information.
12:28
Speaker 1: That's right. You go to the black holes Instagram page
12:30
Speaker 1: and you leave a comment and maybe you'll get it
12:32
Speaker 1: to followers. That's the plant. See there you go first
12:35
Speaker 1: to pose. But yeah, and and this has something to
12:38
Speaker 1: do with and the concept called the ergosphere, which is
12:41
Speaker 1: a sort of a weird, weird thing, right. Yeah, people
12:44
Speaker 1: are used to thinking about black holes is just having
12:46
Speaker 1: an event horizon, but black holes turn out to be
12:48
Speaker 1: much more complicated than that. They have various regions within
12:52
Speaker 1: and outside of the event horizon that might let you
12:55
Speaker 1: tap into it to use its energy. And so that's
12:58
Speaker 1: the central part of this concept. And then to buy
13:00
Speaker 1: Roger Penrose to tap into the energy of a black
13:03
Speaker 1: hole through its ergosphere. Right, So that's kind of a
13:06
Speaker 1: strange word. So as usual, we were wondering how many
13:08
Speaker 1: people out there had heard of this concept of the
13:11
Speaker 1: ergosphere or know that it's related to black holes. So
13:15
Speaker 1: Daniel went out there into the Internet to ask people
13:17
Speaker 1: the question, what do you think is an ergo sphere?
13:20
Speaker 1: And things very much to our volunteers. If you'd like
13:23
Speaker 1: to participate, please just email me. It's very easy. You
13:26
Speaker 1: can record your answers at home, in the leisure of
13:28
Speaker 1: your bathrobe or whatever you like. Please just email us
13:31
Speaker 1: two questions at Daniel and Jorge dot com. Right, but
13:34
Speaker 1: you don't have to wear a bathrobe to answer it
13:36
Speaker 1: to you? Or is that a weird little request just
13:38
Speaker 1: from you. You don't have to wear anything. You don't
13:41
Speaker 1: have to tell me what you're wearing. It's totally up
13:43
Speaker 1: to you. No dress code for these questions. Well, I
13:46
Speaker 1: feel like the more we talk about this, the creepier
13:49
Speaker 1: it gets. Anyways, here's what people have to say. People
13:52
Speaker 1: have some pretty interesting answers ergo the following. Well, that
13:56
Speaker 1: makes me think of two things. The exosphere, which is
13:59
Speaker 1: the sort of of um for this limitations I think
14:04
Speaker 1: of our planet, right, the exosphere is like the furthest
14:09
Speaker 1: layer out maybe before the magnetosphere you think of like
14:12
Speaker 1: atmo tripo sphere. So maybe ergosphere has something to do
14:16
Speaker 1: with that layering system of of different tiered spheres around
14:21
Speaker 1: the Earth. But it also makes me think of ergonomics,
14:25
Speaker 1: So maybe it has something to do with the most
14:29
Speaker 1: ergonomic the most efficient way to have a spear or
14:34
Speaker 1: um some sort of three dimensional object. I happen to
14:38
Speaker 1: know that ergo means work and sphere is a round object.
14:43
Speaker 1: If I had to guess, I would say it's some
14:46
Speaker 1: kind of moving or working around object, or surrounds something
14:52
Speaker 1: that's round that's moving. That's the best guess I got through.
14:56
Speaker 1: Sphere obviously makes me think of the term atmosphere, but
15:00
Speaker 1: it's nothing I ever heard in relation to Earth, So
15:04
Speaker 1: I would think maybe it has to do with the
15:05
Speaker 1: atmosphere of other planets, maybe even the atmosphere around stars. Well,
15:12
Speaker 1: it sounds like ergonomics, but I'm guessing it doesn't have
15:16
Speaker 1: anything to do with that, so maybe some sort of atmosphere.
15:22
Speaker 1: All right. People had some pretty good answers here. I
15:25
Speaker 1: mean people sort of related it to ergonomics, which is
15:28
Speaker 1: maybe sort of related, right because someone as someone pointed
15:31
Speaker 1: out the word ergo means work. Yeah. I like that
15:33
Speaker 1: when people have no idea what I'm talking about, they
15:35
Speaker 1: try to break down the linguistics and understand the origins
15:38
Speaker 1: of the word, because that assumes that somebody out there
15:41
Speaker 1: in the astronomy community has made a sensible choice of names.
15:45
Speaker 1: For this thing. Ha ha ha the fools, little did
15:48
Speaker 1: they know? You just picked names out of a hat.
15:50
Speaker 1: That's right. It is a bit of a leap of faith.
15:52
Speaker 1: So I appreciate that. Thank you. That's a vote of
15:54
Speaker 1: confidence right there for astronomical naming. But sort of is
15:58
Speaker 1: that true? Does ergo really mean work? Like that's where
16:00
Speaker 1: ergonomics come from. I just kind of got my mind
16:03
Speaker 1: blown a little bit. Yeah, ergonomics is like, how do
16:06
Speaker 1: you say comfortably while you do work? I see, it's
16:08
Speaker 1: not the economics of work, and there's the anomics of
16:13
Speaker 1: the ergo. But yeah, so it has something to do
16:17
Speaker 1: with black holes and also work, which is kind of
16:20
Speaker 1: what we're talking about, right, getting black holes to work
16:22
Speaker 1: for us exactly. The ergo sphere plays an important role
16:26
Speaker 1: in trying to extract work from a black hole, to
16:29
Speaker 1: get it to give you energy, and also to do
16:31
Speaker 1: it in a comfortable posture so that it doesn't get
16:34
Speaker 1: lower back paint. All right, well, Daniel, maybe let's start
16:37
Speaker 1: at the beginning here and maybe step us through what
16:39
Speaker 1: exactly is a black hole for those of us who
16:42
Speaker 1: had not heard about it before or heard our podcast.
16:45
Speaker 1: So black hole is the most dramatic feature of Einstein's
16:49
Speaker 1: general relativity, this concept that gravity is not just a force.
16:54
Speaker 1: It's not just the way two things tug at each other.
16:57
Speaker 1: But it's not really a force. It just comes out
16:59
Speaker 1: of the act that space itself is curved. So when
17:02
Speaker 1: you have a really massive object, it curves space time,
17:06
Speaker 1: meaning that it changes the relationship between points and makes
17:09
Speaker 1: some of them closer and some of them further, so
17:12
Speaker 1: that light, for example, appears to travel in a curve.
17:15
Speaker 1: It's very naturally moving through curved space. So matter bends space.
17:20
Speaker 1: It tells space how to curve, and then space tells
17:23
Speaker 1: matter how to move. And if you have enough matter somewhere,
17:27
Speaker 1: if you have enough density of stuff in a small
17:30
Speaker 1: enough area, then you curve space so much that it's
17:34
Speaker 1: distorted that every path now leads towards the center. And
17:38
Speaker 1: that's what a black hole is. It's a region of
17:40
Speaker 1: space where every path now leads towards the center of
17:43
Speaker 1: the black hole, making it impossible to exit. Some people
17:47
Speaker 1: think it's because gravity is so strong. It's like tugging
17:49
Speaker 1: on those photons and making it impossible for them to leave.
17:52
Speaker 1: That sort of a Newtonian view of a black hole
17:54
Speaker 1: A better way to think about it is that space
17:56
Speaker 1: is so distorted that every future you have ends in
18:00
Speaker 1: the singularity. Every path you could take always ends at
18:03
Speaker 1: the center of the black hole if you're inside the
18:05
Speaker 1: event horizon, right, because like even the Earth does that, right,
18:09
Speaker 1: Like the Earth technically sort of bend space time around
18:12
Speaker 1: it so that it to us, you know, it's kind
18:14
Speaker 1: of down is the only way to go, right, I
18:16
Speaker 1: mean the gravity we feel now sitting here, Like the
18:19
Speaker 1: reason I'm sitting in my ergonomic chair is that space
18:22
Speaker 1: time around me is bent in such a way that
18:25
Speaker 1: it makes my body go towards the center of the Earth. Yeah, precisely,
18:29
Speaker 1: every mass been space, not just black holes, not just
18:32
Speaker 1: the Sun, not just the Earth, but you and the
18:35
Speaker 1: banana you ate this morning also bend space. It's just
18:38
Speaker 1: that the amount of bending depends on the amount of mass,
18:41
Speaker 1: and so the more mass you have in a small
18:43
Speaker 1: amount of space, the more bending you get. Right. And
18:46
Speaker 1: so a black hole is is sort of like the Earth,
18:48
Speaker 1: but just super duper dense, right, like a lot more
18:52
Speaker 1: dancer and a lot more massive. Yeah, And you can
18:55
Speaker 1: make a black hole out of almost any mass. If
18:57
Speaker 1: you took the Earth for example, and compactified it down
18:59
Speaker 1: to the size of peanut. All that same matter, everything
19:02
Speaker 1: that's in and on the Earth, squeeze down to less
19:05
Speaker 1: than a centimeter, you would get a black hole, and
19:08
Speaker 1: it would have the same gravitational strength as the Earth
19:11
Speaker 1: does now, but you could get much closer to most
19:14
Speaker 1: of that mass. So if you got really close to
19:16
Speaker 1: that peanut, it would have a very very strong pull
19:18
Speaker 1: on you. Right. In fact, it's kind of mind blowing
19:20
Speaker 1: to think about it. Like if you took the Earth
19:22
Speaker 1: and you like only left like a mile of Earth
19:26
Speaker 1: at the surface, right, Like if you if you hallowed
19:28
Speaker 1: it out kind of like an eggshell, he took everything
19:31
Speaker 1: that was in the middle the yolk, and you squeeze
19:33
Speaker 1: it down to the size of a peanut. Then like
19:35
Speaker 1: we wouldn't tell the difference, right, Like life would just
19:37
Speaker 1: go on exactly the same way, you know, like the
19:41
Speaker 1: center of the return to a black hole, and we
19:42
Speaker 1: wouldn't maybe feel it, well, you wouldn't feel it gravitationally,
19:45
Speaker 1: that's for sure. You would have the same gravitational force
19:48
Speaker 1: on yourself, that's true. Of course, it would change, you know,
19:51
Speaker 1: tectonics and lava flow and all sorts of other stuff.
19:54
Speaker 1: And I don't think that a shell of the Earth
19:56
Speaker 1: that's a mile thick could hold itself up. But from
19:58
Speaker 1: a gravitational point of you absolutely you'd feel the same force.
20:02
Speaker 1: Because for gravity, you can always replace an object with
20:05
Speaker 1: a point particle at its center of mass with that
20:08
Speaker 1: same mass, and you'll feel the same gravity. You're not
20:11
Speaker 1: sensitive to the details of how the object is put together, right,
20:14
Speaker 1: And in fact, it would still kind of keep on spinning,
20:17
Speaker 1: right because black holes can spin, That's right. Black holes
20:20
Speaker 1: can spin. And if you make a black hole out
20:22
Speaker 1: of something that is spinning, then that black hole has
20:25
Speaker 1: to spin because spin is something that's conserved in this universe.
20:29
Speaker 1: Something that's spinning can't stop spinning unless you have some
20:32
Speaker 1: external torque on it. So in an isolated system like
20:35
Speaker 1: a star out in space, if it's spinning and then
20:38
Speaker 1: collapses into a black hole, that black hole has to
20:40
Speaker 1: have the same amount of spin as the original star.
20:43
Speaker 1: And one thing that's interesting about black holes is that
20:45
Speaker 1: you know, like if you made a black hole out
20:47
Speaker 1: of the Earth, you sort of know what was inside
20:49
Speaker 1: of that black hole, right, it would be the Earth
20:51
Speaker 1: just really squished together, but maybe not right, like maybe
20:55
Speaker 1: when things get squished down that much, things maybe change,
20:58
Speaker 1: and we have no idea what's going on when you
21:00
Speaker 1: squeeze it that small. We definitely have no idea what's
21:02
Speaker 1: going on inside the black hole. Like general relativity tells us,
21:06
Speaker 1: you don't have matter in the same way that we do.
21:08
Speaker 1: That it's all squeezed down into a singularity, a point
21:11
Speaker 1: of zero volume but non zero mass, and that's the
21:15
Speaker 1: sort of classical picture. That's what Einstein's prediction tells us.
21:18
Speaker 1: But we also know that that's wrong. That can't possibly
21:21
Speaker 1: be what's actually inside a black hole for a couple
21:24
Speaker 1: of reasons. One is that there's an infinity, there's an
21:27
Speaker 1: infinite density, so it's not as much a prediction of
21:30
Speaker 1: general relativity as a breakdown of general relativity is, like
21:33
Speaker 1: this is where general relativity doesn't work anymore. And the
21:36
Speaker 1: other is that we know it violates quantum mechanics. You
21:38
Speaker 1: can't have a point of zero size and know exactly
21:41
Speaker 1: where it is and have it have a zero velocity.
21:43
Speaker 1: It's just too much information. That amount of information doesn't
21:46
Speaker 1: exist in the universe. So we don't know what's going
21:49
Speaker 1: on with the matter that's inside a black hole. But
21:51
Speaker 1: we know it's definitely not a singularity. It's probably some
21:54
Speaker 1: other crazy froth and quantum stuff. And the closest analog
21:59
Speaker 1: we have our new tron stars, which are very very
22:02
Speaker 1: dense remnants from stars that are not dense enough to
22:05
Speaker 1: become a black hole. But close and inside the heart
22:08
Speaker 1: of a neutron star there are crazy things going on
22:11
Speaker 1: with very high temperatures and pressures and weird forms of
22:14
Speaker 1: matter that we've never seen before, all new kinds of
22:16
Speaker 1: pasta inside maybe turns into cuscous right, like a little
22:19
Speaker 1: tiny ball, a fuzzy infinite singularity cosmic cuscoose. That sounds
22:24
Speaker 1: like a nice name for a dish. All right, Well,
22:26
Speaker 1: black holes also have something pretty interesting called an ergosphere
22:30
Speaker 1: that may be able to do work for us and
22:32
Speaker 1: solve all of our energy needs. So let's get into
22:35
Speaker 1: what an ergosphere is. But first let's take a quick break. Alright,
22:51
Speaker 1: we're talking about black holes and their ergosphere. That's apparently
22:55
Speaker 1: a feature of black holes that we may be able
22:58
Speaker 1: to tap into for energy. I guess data would be
23:01
Speaker 1: to go to a black hole, Daniel and set up
23:04
Speaker 1: like an ergosphere energy sucking station. Next event, Yeah, precisely,
23:09
Speaker 1: and ergospheres are really cool because they're a feature of
23:12
Speaker 1: a more complicated black hole. Like typical black hole you
23:16
Speaker 1: imagine is what you just described. Take the Earth, compactify
23:19
Speaker 1: it down to a peanut, you get a black hole.
23:21
Speaker 1: But most actual black holes out there in the universe
23:24
Speaker 1: have more than just mass. They also have spin, like
23:27
Speaker 1: we talked about, and the reason is that basically everything
23:30
Speaker 1: out there in the universe that could make a black
23:32
Speaker 1: hole is spinning. It's very rare to find something out
23:35
Speaker 1: there in the universe that's not spinning in some way.
23:37
Speaker 1: The Sun is spinning, the Earth is spinning, or Solar
23:40
Speaker 1: system spinning, the galaxy is spinning. Everything is spinning. So
23:42
Speaker 1: if you're gonna make a black hole, then it's gonna
23:44
Speaker 1: end up spinning and spinning. Black Holes are more complicated
23:48
Speaker 1: than your normal, like vanilla short sized black hole, and
23:52
Speaker 1: they have more than just an event horizon. They have
23:54
Speaker 1: several regions both within and outside the event horizon, with
23:58
Speaker 1: really fascinating different effects on the spacetime. WHOA, and I
24:03
Speaker 1: guess you know, it's kind of weird to think of
24:05
Speaker 1: a whole spinning, right like a hole is the lack
24:08
Speaker 1: of something, you know, It's like if I dig a
24:10
Speaker 1: hole on the ground, that hole is not. It's weird
24:13
Speaker 1: to think that the whole will spin. It is weird
24:16
Speaker 1: to think about that, And there's sort of two things
24:18
Speaker 1: to grapple with their one is what's spinning on the
24:21
Speaker 1: inside of the hole, and the other is what's spinning
24:23
Speaker 1: on the outside. On the inside, it's hard to think
24:26
Speaker 1: about things spinning because we imagine a singularity at the
24:30
Speaker 1: heart of the black hole, at least in classical general relativity,
24:33
Speaker 1: and a singularity has no size as zero volume. So
24:37
Speaker 1: it's sort of like when we talk about a quantum particle,
24:40
Speaker 1: an electron that has spin, but we don't say it
24:42
Speaker 1: physically spin. This can't spin because there's no extent to it.
24:46
Speaker 1: It doesn't change by spinning. So black holes that spin
24:50
Speaker 1: don't have singularities in them. They have something else. They
24:53
Speaker 1: have a ring inside. It's like a ring ularity instead
24:56
Speaker 1: of a singularity. That's a nice pun, but I guess
25:00
Speaker 1: maybe one way to picture it is that if you
25:02
Speaker 1: like imagine a black hole forming, right, it's not every
25:05
Speaker 1: the stuff that makes that goes into the black hole
25:07
Speaker 1: is not going to go straight in and compact itself.
25:09
Speaker 1: It's usually like stuff that's swirling and because of gravity,
25:13
Speaker 1: it's swirling towards the middle, and then at some point
25:15
Speaker 1: it gets squished so much that it enters the event horizon.
25:18
Speaker 1: But maybe like the ideas that maybe as it goes
25:20
Speaker 1: in it preserves some of that spin, so that maybe
25:23
Speaker 1: inside of the black hole things are still spinning like
25:26
Speaker 1: the center. Maybe we don't know what's going on, but
25:28
Speaker 1: the stuff right outside the center up until the event horizon,
25:31
Speaker 1: maybe that stuff is still going around in circles. Definitely
25:34
Speaker 1: it is, and we see that right, that's what the
25:36
Speaker 1: accretion disk is. It's stuff that has so much spin
25:40
Speaker 1: that it hasn't yet fallen into the black hole. Like
25:42
Speaker 1: you might wonder, how does anything avoid falling into a
25:45
Speaker 1: black hole or the same way that the Earth avoids
25:48
Speaker 1: falling into the Sun, because we are spinning around that
25:50
Speaker 1: we have orbital velocity, and we can't just like lose that.
25:53
Speaker 1: It can't just go away. The Earth can't just stop
25:55
Speaker 1: spinning around the Sun and fall into the Sun. In
25:58
Speaker 1: the same way the stuff that on deck to go
26:01
Speaker 1: into the black hole but is spinning around it. You
26:04
Speaker 1: can't just like give up that spin and fall in
26:07
Speaker 1: the way things fall into the black holes, that they
26:09
Speaker 1: bump into each other and that slows them down or
26:11
Speaker 1: knocks one of them into the black hole and knocks
26:14
Speaker 1: one of them out. So you're write things that are
26:16
Speaker 1: about to go into a black hole mostly spin around
26:19
Speaker 1: it and then fall in. And if you think about it,
26:21
Speaker 1: if you're just like a random particle headed towards a
26:24
Speaker 1: black hole, unless you're headed exactly at the center of it,
26:27
Speaker 1: then you have some spin relative to the center of
26:30
Speaker 1: the black hole. Imagine just a spinning disk. For example,
26:33
Speaker 1: if you're a particle and you hit a spinning disk,
26:35
Speaker 1: unless you hit it at the very center, then you're
26:37
Speaker 1: gonna make that disc spin faster or slower. Right, But
26:41
Speaker 1: I guess I mean like, as I have this sort
26:43
Speaker 1: of spin relative to the black hole, and then as
26:45
Speaker 1: I enter the event horizon and before I fall to
26:49
Speaker 1: the very core of the black hole, maybe I'm still
26:52
Speaker 1: going around in circles or in a spiral. You are, yeah,
26:55
Speaker 1: and you still have that spin exactly. And so things
26:58
Speaker 1: are spinning on the outside of the black hole, and
27:00
Speaker 1: things are spinning on the inside of the black hole,
27:02
Speaker 1: and that's just because of conservation of angular momentum, right,
27:06
Speaker 1: It can't go away, and so if the black hole
27:08
Speaker 1: sort of isolated in space, then the stuff that started
27:12
Speaker 1: forming the black hole has to keep spinning. And what's
27:15
Speaker 1: fascinating is that, you know, maybe the insingularity, it's like
27:19
Speaker 1: a circle of zero volume that's spinning, so you can
27:22
Speaker 1: have angular momentum. But even more interesting is what's going
27:24
Speaker 1: on outside the event horizon, because outside the event horizon
27:28
Speaker 1: of a spinning black hole is not like a hole
27:30
Speaker 1: that you just sort of like slide into. It's more
27:33
Speaker 1: like a whirlpool, which I think you were like describing
27:35
Speaker 1: as you fall in, your spinning around it, and it's
27:38
Speaker 1: so strong that it's spinning space itself. It's like dragging
27:42
Speaker 1: space around with it as it spins. Well, what do
27:45
Speaker 1: you mean, like it's swirling spacetime itself. Yeah, I remember
27:48
Speaker 1: we had an episode about frame dragging. This incredible experiment,
27:52
Speaker 1: gravity Probe B that has the smoothest balls known demand
27:56
Speaker 1: spinning in these gyroscopes out in a satellite in space,
28:00
Speaker 1: and these gyroscopes can detect how the Earth spinning is
28:04
Speaker 1: dragging space with it, which makes those gyroscopes twist a
28:08
Speaker 1: tiny bit. So this has the effect of spinning things,
28:11
Speaker 1: not just pulling on them. So, because the Earth is spinning,
28:14
Speaker 1: it doesn't just tug on satellites out in space. It
28:17
Speaker 1: also gently spins them a little bit. And that's because
28:20
Speaker 1: it's dragging space with it. Sort of like imagine putting
28:24
Speaker 1: a fork into a big sheet of pasta and spinning it.
28:28
Speaker 1: The whole sheet of pasta then gets like twirled up
28:31
Speaker 1: around the fork. Whoa, And that's just sort of a
28:33
Speaker 1: consequence of the speed limit of the universe. Kind of like,
28:37
Speaker 1: why does that dragging occur? Why do things get spun
28:40
Speaker 1: around if they're not touching actually the center. It's just
28:44
Speaker 1: an extension of the question, you know, why does space
28:46
Speaker 1: get bent around masses? We don't know. It's just something
28:49
Speaker 1: we've observed. And the effect of space getting bent is
28:52
Speaker 1: the force of gravity. Now, the effect of space dragging
28:56
Speaker 1: around a spinning object is that it causes a spin
28:59
Speaker 1: on things. Remember, the curvature of space creates this fictitious
29:03
Speaker 1: force of gravity. Gravity is not just like pulling you
29:06
Speaker 1: towards the densest spot. It's also spinning you a little bit.
29:09
Speaker 1: So you're saying kind of like the Earth spinning right
29:12
Speaker 1: now is imparting a little bit of spin on the
29:15
Speaker 1: Moon for example. Yes, and it's a very very subtle
29:18
Speaker 1: effect compared to its tug, which is why it took
29:20
Speaker 1: a very sensitive experiment. We have a whole episode on
29:23
Speaker 1: gravity probe B and what is frame dragging people should
29:26
Speaker 1: dig into if they're interested in that. The effect of
29:28
Speaker 1: space being spun around on the outside past the event
29:32
Speaker 1: horizon of a spinning black hole creates this new region
29:36
Speaker 1: we call the ergosphere. Well wait, let me go back
29:39
Speaker 1: a little bit, Like in the example of the Earth
29:41
Speaker 1: and the Moon, like the Earth spinning is imparting some
29:44
Speaker 1: spin on the Moon, but in the sense that like
29:47
Speaker 1: it's making the Moon spin faster in place, or it's
29:50
Speaker 1: making it spin faster sort of around the Earth spin
29:53
Speaker 1: faster in place. Like if you put an object in
29:56
Speaker 1: orbit around the Earth that wasn't spinning the Earth but
29:58
Speaker 1: very gently started to spin around its own axis. Interesting,
30:02
Speaker 1: and that is that because of sort of like the
30:04
Speaker 1: difference in the distance from the end of the Moon
30:06
Speaker 1: that's furtherest from the Earth, and the difference to that
30:09
Speaker 1: from the point that's closer to the Earth. You know,
30:11
Speaker 1: do you know what I mean? Like, could that be
30:13
Speaker 1: a way to explain why the spinning happens. Yeah, Like,
30:16
Speaker 1: imagine what would happen if you put a ball into
30:18
Speaker 1: a whirlpool. It wouldn't just fall in towards the center.
30:21
Speaker 1: It would start to spin because the current on the
30:23
Speaker 1: inner side of it wouldn't be the same strength as
30:26
Speaker 1: the current on the outer side of it is. That
30:28
Speaker 1: would be an effective rotation on the Earth. I see,
30:31
Speaker 1: like the side of the Moon closer to the Earth
30:34
Speaker 1: is getting maybe pushed along a little bit faster, which
30:37
Speaker 1: is than making the Moon's kind of spin in place. Yeah,
30:40
Speaker 1: it's sort of like tidal forces where the Earth is
30:44
Speaker 1: pulling harder on the near side of the Moon, for example,
30:46
Speaker 1: than the far side because the difference in their distance
30:50
Speaker 1: from the center of the Earth, and that effectively elongates
30:52
Speaker 1: the Moon. In this case, it's the swirling of space time,
30:57
Speaker 1: which is faster closer to the spinning object. The Earth
31:00
Speaker 1: with a black hole, just like the near side of
31:02
Speaker 1: the Moon is being dragged faster than the far side,
31:05
Speaker 1: so it effectively spins the Moon as well as carrying
31:08
Speaker 1: it along in this swirling space time. Alright, So then
31:13
Speaker 1: you're saying that this is kind of what happens outside
31:15
Speaker 1: of a black hole, Like if I'm outside of a
31:17
Speaker 1: black hole, I'm gonna get spun in place because the
31:20
Speaker 1: part of me that's closer to the black hole sort
31:21
Speaker 1: of wants to spin faster around the black hole than
31:23
Speaker 1: the part of me that's furthest away from the black hole.
31:27
Speaker 1: And so now imagine a photon moving around a black hole.
31:31
Speaker 1: We're still outside the event horizon, right, All the same
31:33
Speaker 1: rules apply to a spinning black hole that you can't
31:36
Speaker 1: escape the event horizon. But now this is funny region
31:38
Speaker 1: outside the event horizon. Think about a photon moving around
31:43
Speaker 1: a black hole. A photon moving around a black hole
31:45
Speaker 1: is now moving through space itself that's being dragged. And
31:50
Speaker 1: so there's this region outside the event horizon where a
31:53
Speaker 1: photon moving as fast as it can at the speed
31:56
Speaker 1: of light through that space would appear to be stationary
32:00
Speaker 1: to you. It's sort of like swimming upstream. So say you're,
32:03
Speaker 1: for example, far away from the black hole, and you're
32:05
Speaker 1: watching this spinning black hole, and you see a photon
32:08
Speaker 1: enter this region outside the event horizon and move against
32:12
Speaker 1: the current of the black holes. The black hole spinning
32:15
Speaker 1: one way and the photons going in the other direction.
32:17
Speaker 1: It's sort of like swimming upstream, so like somebody in
32:20
Speaker 1: a whirlpool trying to escape. So you're saying, like the
32:22
Speaker 1: black hole is dragging space around sort of like you said,
32:25
Speaker 1: like the four you know, trailing on a Plato spaghetti,
32:28
Speaker 1: and so the spaghetti is all wanting to sort of
32:30
Speaker 1: troll in one direction. You're saying, what if I shoot
32:32
Speaker 1: a photon that's going in the opposite direction, You're saying,
32:35
Speaker 1: it's gonna seem like it's not moving exactly the same way.
32:38
Speaker 1: A photon inside the event horizon trying to escape the
32:42
Speaker 1: black hole in your sort of normal vanilla black hole
32:45
Speaker 1: would appear to stop right because it can't escape the
32:47
Speaker 1: event horizon. For an outside observer, that photon can appear
32:51
Speaker 1: to have zero velocity as it tries to climb out
32:55
Speaker 1: of the gravitational well of the black holes event horizon,
32:58
Speaker 1: but of course it can't make it out. The analogous
33:00
Speaker 1: behavior for a spinning black hole and a photon and
33:03
Speaker 1: its ergosphere is that the photon is trying to go
33:06
Speaker 1: around the black hole, moving opposite the direction of spin,
33:10
Speaker 1: but unable to overcome the swirling of space itself because
33:13
Speaker 1: it's limited to moving through space at the speed of light.
33:17
Speaker 1: It's like somebody trying to swim against a whirlpool and
33:20
Speaker 1: getting swept up along with it. Now, inside the ergosphere,
33:24
Speaker 1: it gets overcome by the swirling of space, so it
33:27
Speaker 1: actually moves backwards, the opposite direction you would expect. The
33:30
Speaker 1: edge of the ergosphere is defined as the points where
33:33
Speaker 1: the photon appears to be motionless, where its speed is
33:36
Speaker 1: exactly counteracted by the swirling of space, and outside the
33:40
Speaker 1: ergosphere further from the black hole. Of course, photon is
33:43
Speaker 1: going to overcome this swirling of space because it's not
33:46
Speaker 1: as strong whoa I see. So, because you know, the
33:49
Speaker 1: event horizon is where you might in a stationary black hole,
33:53
Speaker 1: that's where a photon that's trying to leave the black
33:55
Speaker 1: hole would seem like it's stuck in space right, not
33:57
Speaker 1: moving right. But you're saying that for a spinning black holes.
34:00
Speaker 1: Because of this dragging effect, there's some weird stuff that
34:03
Speaker 1: happens outside of the event horizon where you can actually
34:06
Speaker 1: maybe see a photon kind of stop in space that's
34:09
Speaker 1: right inside the ergosphere, which is this region outside the
34:12
Speaker 1: event horizon. In order to be like stationary relative to
34:16
Speaker 1: the black hole, you would have to be moving faster
34:18
Speaker 1: than light, and so at the ergosphere. Then what defines
34:21
Speaker 1: the edge of the ergosphere is where a photon which
34:24
Speaker 1: is moving at light speed can be stationary relative to
34:27
Speaker 1: the black hole, and so outside the ergosphere, of course,
34:30
Speaker 1: you can be stationary relative to the black hole without
34:32
Speaker 1: going faster than the speed of light. Inside the ergosphere,
34:35
Speaker 1: because the space is being spun so fast. To be
34:38
Speaker 1: stationary with respect to the black hole, you would have
34:40
Speaker 1: to go faster than the speed of light, which is impossible.
34:43
Speaker 1: So everything, even photons, are like pushed along in this
34:46
Speaker 1: whirlpool outside the event horizon, inside the ergosphere, I thought
34:52
Speaker 1: that was kind of like impossible to see a photon
34:54
Speaker 1: like stop. There's a really subtle and fascinating point here
34:57
Speaker 1: that we're going to dig into in a future episode.
35:00
Speaker 1: It's true that photons are always observed to be going
35:02
Speaker 1: at the speed of light. That's like a well known
35:05
Speaker 1: result of special relativity, But there are some qualifiers to
35:08
Speaker 1: that that are not usually explained. Those qualifiers are that
35:11
Speaker 1: the photon has to be near you is to be
35:13
Speaker 1: a local photon, and it has to be in flat
35:16
Speaker 1: space space without any curvature, So local observers people always
35:21
Speaker 1: see nearby photons moving at the speed of light, but
35:23
Speaker 1: things that are far away from you. General relativity says
35:26
Speaker 1: that if space is curved, you could see photons going
35:29
Speaker 1: at faster than the speed of light, or less than
35:31
Speaker 1: the speed of light, or even stopping, because in general relativity,
35:34
Speaker 1: it's very hard to even define what you mean by
35:37
Speaker 1: the velocity of objects that are far away from you
35:39
Speaker 1: in curved space, Like you wouldn't actually maybe see this
35:42
Speaker 1: photon stopping because you know, there's all kind of weird
35:46
Speaker 1: stuff going on, all sorts of weird stuff going on,
35:48
Speaker 1: and what you mean by velocity in that case is
35:51
Speaker 1: not even well defined. But we'll dig into that in
35:53
Speaker 1: an upcoming episode, right. Not to mention also the question
35:56
Speaker 1: of how do you even see a photon? Right, Like,
35:58
Speaker 1: the only way to see a photon is if it
36:00
Speaker 1: hits your eyeball, Like if it's if a photon it
36:02
Speaker 1: stuck outside of a black hole, how do you even
36:04
Speaker 1: see it? You can't see it, right, You can't even
36:06
Speaker 1: bounce a photon office, right. If you can't get to it,
36:09
Speaker 1: then you can't interact with it, and you can't observe
36:11
Speaker 1: it all. Right, So then an ergosphere is sort of
36:13
Speaker 1: the region of space around a black hole, of a
36:15
Speaker 1: spinning black hole, where space is being dragged so much
36:19
Speaker 1: it's like it can overpower a photon. Yeah. And there's
36:22
Speaker 1: one more really cool wrinkle about this, which is the
36:24
Speaker 1: shape of the ergosphere. You might think it would be
36:26
Speaker 1: a sphere, right, Well, wrong, It's more like a taurus
36:30
Speaker 1: or a donut. It's not spherically symmetric because there's a
36:33
Speaker 1: spin axis and the effect is due to spin, So
36:37
Speaker 1: the ergosphere is like a doughnut around that spin axis.
36:41
Speaker 1: There's actually no ergosphere past the event horizon along the
36:44
Speaker 1: north south spin axis because there's no spin in that direction.
36:49
Speaker 1: But on the plane where it's spinning perpendicular to the
36:52
Speaker 1: north south axis, the ergosphere can extend out like fifty
36:56
Speaker 1: percent further than the event horizon, depending of course, on
36:59
Speaker 1: how fast the black hole the spinning, And so there's
37:02
Speaker 1: no ergosphere sort of like on the north pole. In
37:04
Speaker 1: the south pole, it's sort of like a big fat
37:06
Speaker 1: blob around the event horizon along the equator. Oh, I see,
37:10
Speaker 1: But what is it a donut like a taurus or
37:12
Speaker 1: is it more like a you know, one of those
37:14
Speaker 1: jelly filled donuts, which is like just a flat block.
37:19
Speaker 1: It should have been called the ergo jelly filled donut.
37:21
Speaker 1: You're exactly right, no, but but seriously, like, what's the shape.
37:25
Speaker 1: Is it shaped like like a doughnut with a hole
37:26
Speaker 1: in the middle, or is it shape more like a
37:28
Speaker 1: blobby piece of bread. It's a blobby pizza dough that's spinning, right,
37:31
Speaker 1: and so it doesn't actually have a hole in the middle.
37:34
Speaker 1: At the very core. It's minimum size is the event
37:36
Speaker 1: horizon itself, and then it grows out to me to
37:39
Speaker 1: have a larger radius at the equator. So it's like
37:42
Speaker 1: a spinning piece of pizza dough. I feel like there's
37:44
Speaker 1: a mathematical name for that kind of shape, but we
37:47
Speaker 1: just don't can't come up with it right now. It's
37:49
Speaker 1: not jelly filled donut, is it. It's the jelly donut.
37:51
Speaker 1: It's it's totally the jelly filled donut. I hear geometrists
37:55
Speaker 1: talk about that all the time. All right, Well, apparently
37:58
Speaker 1: you can use this ergosphere, this jelly filled doughnut area
38:02
Speaker 1: around a spinning black hole to get some work out
38:04
Speaker 1: of the black hole. So let's get into how to
38:07
Speaker 1: do that. But first let's take a quick break, all right, Daniel,
38:22
Speaker 1: how do you put a giant jelly filled donut that
38:25
Speaker 1: bend space and time to work for you, instead of
38:28
Speaker 1: just adding some weight around your middle part. The idea
38:31
Speaker 1: invented by Roger Penrose is to throw something into the
38:34
Speaker 1: black hole's ergosphere and have a gravitationally slink shot out
38:38
Speaker 1: because of the swirling of space time, and have it
38:41
Speaker 1: come out with more speed more energy than it had
38:44
Speaker 1: going in. That you have, for example, a rock or
38:46
Speaker 1: a spaceship or something, and you let it come close
38:50
Speaker 1: to the black hole. You do not go inside the
38:51
Speaker 1: event horizon, or of course it's lost forever. You just
38:54
Speaker 1: go into the whirlpool near it, inside the ergosphere. And
38:58
Speaker 1: what happens there is your into this whirlpool, you pick
39:01
Speaker 1: up a bunch of energy because the black hole is
39:03
Speaker 1: pulling on you, so it's speeding you up. So now
39:06
Speaker 1: you have this energy. But of course you want to
39:08
Speaker 1: get out right. You don't want to just spend the
39:10
Speaker 1: rest of your life swirling around a black hole eventually
39:12
Speaker 1: to fall in. So what you have to do is
39:14
Speaker 1: somehow escape the vicinity of this black hole. But now
39:18
Speaker 1: you've picked up all of this energy which is pulling
39:20
Speaker 1: you in towards the center. So what you have to
39:22
Speaker 1: do is sacrifice something. You like chop off a piece
39:25
Speaker 1: of your block, or you use some fuel or something.
39:28
Speaker 1: You throw something into the event horizon. You sacrifice some
39:32
Speaker 1: part of your ship into the event horizon, which gives
39:35
Speaker 1: you momentum the other direction kicks you out and in
39:37
Speaker 1: the end you come out with more energy than you
39:40
Speaker 1: came in with. Wait what Okay, So I guess the
39:44
Speaker 1: idea is to throw something at a black hole but
39:47
Speaker 1: not and have it sort of like do a swing
39:50
Speaker 1: by of the black hole without going into the event horizon,
39:53
Speaker 1: because if it goes into the event horizon, then your toast.
39:55
Speaker 1: But you just go right outside of it and somehow
39:58
Speaker 1: you're able to escape that when of something escape anyways,
40:02
Speaker 1: like you know, we're swinging around the sun. You can
40:04
Speaker 1: swing a satellite towards the Sun, but it'll just come
40:07
Speaker 1: out the other way. Yeah, it's possible to whip around
40:10
Speaker 1: the Sun and come out the other side. It's harder
40:12
Speaker 1: to do that with a black hole because the angles
40:15
Speaker 1: of escape start to shrink down as you get close
40:17
Speaker 1: to the black hole, until you have to be going
40:19
Speaker 1: straight away perpendicular from the black hole in order to escape.
40:23
Speaker 1: We do something similar all the time. Change the direction
40:27
Speaker 1: of your space probe and give it a little bit
40:29
Speaker 1: of a speed boost. You can swing it around Jupiter, right,
40:33
Speaker 1: It doesn't have to fall into Jupiter. You can just
40:35
Speaker 1: go around Jupiter and it can pick up some energy.
40:38
Speaker 1: And we talked about that once on a previous episode.
40:40
Speaker 1: And what that does is steal a little bit of
40:43
Speaker 1: the energy from Jupiter and it gives it to the probe.
40:45
Speaker 1: This is an analogy to that, but it's more powerful
40:48
Speaker 1: because the ergosphere has a lot of energy in it,
40:52
Speaker 1: So it's like a supercharged version of this gravitational slingshot.
40:55
Speaker 1: I see. So then the idea is that I sling
40:57
Speaker 1: shot something into a black hole and somehow, actusly it
41:00
Speaker 1: comes out with more energy than it had when it
41:02
Speaker 1: went in. Yeah, and it's not a miracle, you know,
41:04
Speaker 1: it's physics. The reason it has more energy than when
41:07
Speaker 1: it came in is that it's stealing some of that
41:09
Speaker 1: energy from the black hole. The black hole is using
41:12
Speaker 1: its gravity, it's using the spinning mass to spin space
41:17
Speaker 1: time and you're getting carried along with it. So it's
41:19
Speaker 1: gusting up your kinetic energy. It's giving you more velocity.
41:23
Speaker 1: I see. So The idea would be, like I throw
41:25
Speaker 1: a rock at the black hole, it goes through the ergosphere,
41:29
Speaker 1: it picks up some spin like it's been some space,
41:31
Speaker 1: and then it shoots out the other end, or maybe
41:34
Speaker 1: it comes back around towards me. So now I have
41:36
Speaker 1: the same rock that I threw in, but now it's spinning,
41:39
Speaker 1: which has some extra energy to it. Not quite. You
41:42
Speaker 1: throw a rock near a black hole into the ergosphere,
41:45
Speaker 1: it wouldn't necessarily just come out right. So that comes
41:47
Speaker 1: that close to a black hole is very likely eventually
41:50
Speaker 1: going to fall into the black hole. So if you
41:52
Speaker 1: throw it that close to a black hole, it's probably doomed.
41:55
Speaker 1: It's technically possible for it to escape, but it's probably doomed,
41:59
Speaker 1: but it will pick up a bunch more energy before
42:01
Speaker 1: it falls into the black hole because spacetime is dragging
42:04
Speaker 1: it is pulling on it. Now, in order to get
42:07
Speaker 1: it out of the ergosphere, you're gonna have to either
42:09
Speaker 1: burn some fuel on your rocket or split that rock
42:12
Speaker 1: in half so that part of it falls into the
42:14
Speaker 1: center of the black hole and part of it gets
42:16
Speaker 1: a push out of the ergosphere. But you're saying, then
42:19
Speaker 1: what comes back is only half a rock. Yes, you
42:21
Speaker 1: get half a rock back, but it has more energy
42:24
Speaker 1: than the rock you threw in. What do you mean,
42:25
Speaker 1: like it's coming at me faster than the one I like,
42:28
Speaker 1: I drop it in, but it comes at me with
42:31
Speaker 1: a whole bunch of velocity. Yeah, exactly. And so you
42:33
Speaker 1: throw the rock in and you get a smaller rock out,
42:36
Speaker 1: but has overall more kinetic energy than the rock you
42:39
Speaker 1: threw in. Oh, I see. So it's like I'm feeding
42:41
Speaker 1: the black hole and in exchange, I'm getting shot at
42:44
Speaker 1: by little rocks. Yes, but it's not an even exchange, right.
42:48
Speaker 1: The black hole is getting some mass because it gets
42:51
Speaker 1: part of your rock, but it's giving you more energy
42:54
Speaker 1: than you're giving it. So you're extracting energy from the
42:58
Speaker 1: black hole. Wait what so the black hole loses in
43:01
Speaker 1: this little scheme of your The black hole slows down
43:05
Speaker 1: a tiny bit. If you do this, you're essentially stealing
43:08
Speaker 1: some of the energy from the black hole spin, which
43:10
Speaker 1: effectively slows it down a tiny bit, the same way
43:14
Speaker 1: hawking radiation shrinks the size of a black hole by
43:17
Speaker 1: stealing some of its energy, giving a little boost to
43:20
Speaker 1: a particle. This steals some of the energy of the
43:22
Speaker 1: black hole spin and slows down its spin. So does
43:27
Speaker 1: that mean that then you're sort of killing the black
43:29
Speaker 1: hole a little bit. You're slowing down the black hole
43:32
Speaker 1: stealing some of its energy, and so you can steal
43:35
Speaker 1: some like almost thirty percent of the energy of the
43:38
Speaker 1: black hole can be stored in its spin. So yeah,
43:41
Speaker 1: you can steal that much energy from a black hole
43:44
Speaker 1: using this idea. Oh I see, but you wouldn't kill
43:46
Speaker 1: the black hole because the only thing you can steal
43:48
Speaker 1: is a spin of it. You can't steal the actual
43:50
Speaker 1: black hole in the middle. Yeah, but remember that mass
43:54
Speaker 1: is just a reflection of energy that's stored inside, and
43:57
Speaker 1: so the spin of the black hole contributes to its mass. Right,
44:01
Speaker 1: a black hole that's spinning is more massive than a
44:04
Speaker 1: black hole with the same stuff in it that's not
44:07
Speaker 1: spinning because the whole gravitational energy reflects all the internal energy,
44:11
Speaker 1: even spin. So you are stealing some of its mass.
44:14
Speaker 1: You're right, But I guess what I mean is that
44:16
Speaker 1: you can steal energy from it. But at some point
44:18
Speaker 1: the black hole is gonna stop spinning. It's going to
44:21
Speaker 1: be game over for your little energy sucker. That's right,
44:23
Speaker 1: you'll suck all the rotational energy out of this giant
44:26
Speaker 1: cosmic battery, and then all you'll be left with is
44:29
Speaker 1: a short child black hole. You'll shrink the ergosphere gradually
44:32
Speaker 1: down to the event horizon, and it will disappear because
44:34
Speaker 1: short child black holes, normal ones that don't spin, don't
44:38
Speaker 1: have an ergosphere. Right, But it will be a bigger
44:40
Speaker 1: black hole, short child black hole, because you fed it
44:43
Speaker 1: all these little rocks. That's true, but you've stolen more
44:47
Speaker 1: energy than you've given so net it'll lose energy and
44:51
Speaker 1: therefore lose mass, but you lose a bunch of rocks
44:55
Speaker 1: of rock exactly. And you might remember this actually is
44:59
Speaker 1: a plot point in my favorite movie Interstellar. There's some
45:02
Speaker 1: moment when they realize they don't have enough fuel to
45:05
Speaker 1: get where they're going, and so they do a black
45:07
Speaker 1: hole gravitational slingshot where they dive into the ergosphere and
45:11
Speaker 1: take advantage of the penrose process. Wow, and then what
45:14
Speaker 1: did they sacrifice? They burned a bunch of fuel, right,
45:17
Speaker 1: And it's effectively the same thing. If you use fuel,
45:19
Speaker 1: you're giving yourself a momentum kick, and you're kicking something
45:22
Speaker 1: else out the other end. Interesting, all right, So then
45:25
Speaker 1: we could potentially get energy from this ergosphere, but you
45:29
Speaker 1: got to shoot a lot of rocks. Is there more
45:31
Speaker 1: sort of like practical scenario or some sort of like
45:33
Speaker 1: device that would do this automatically. You could do this
45:36
Speaker 1: also with photons, right, You can drop photons into the
45:39
Speaker 1: ergosphere and they would come out with more energy than
45:42
Speaker 1: they went in. They wouldn't be going faster, but it
45:45
Speaker 1: would change their frequency. And so if you build some
45:48
Speaker 1: device that like dropped photons into the ergosphere and they
45:52
Speaker 1: came out, and you could basically be harrasting the energy
45:55
Speaker 1: of the black hole by increasing the power of your light.
45:58
Speaker 1: All right, So then the scheme would be to gather
46:00
Speaker 1: a bunch of rocks, throw them at a black hole,
46:03
Speaker 1: and then have something that trends when when they come
46:06
Speaker 1: back faster at us, we somehow harness that energy. If
46:10
Speaker 1: you did this, for example, to the black hole at
46:12
Speaker 1: the center of our Milky Way, Sagittarius a star, you
46:15
Speaker 1: could steal as much energy as all the stars in
46:20
Speaker 1: the Milky Way are putting out in a billion years.
46:23
Speaker 1: So we're talking about like vast cosmic amounts of energy.
46:26
Speaker 1: It would just really dwarf you all of human energy production. Right,
46:30
Speaker 1: because I think what you mean is that the black
46:33
Speaker 1: hole at the center of our galaxy has all that
46:36
Speaker 1: energy stored in its spin. It has as much energy
46:39
Speaker 1: in its spin as the light that the Milky Way
46:41
Speaker 1: emits in a billion years. Yeah, there's a huge amount
46:44
Speaker 1: of energy stored in the spin of the black hole
46:46
Speaker 1: at the center of the galaxy. So that could potentially
46:49
Speaker 1: be stolen from us by some rocky scheme. Exactly. Maybe
46:55
Speaker 1: aliens are building pasta makers right next to the center
46:58
Speaker 1: of the galaxy. Yeah, thats right. Does it work with
47:00
Speaker 1: orzo pasta too, Like if I throw a bunch of
47:02
Speaker 1: little or zo collets, do they come out? You know?
47:06
Speaker 1: Like like Linquini on the other side, I suppose, So
47:09
Speaker 1: you know, for me, the question is is it theoretically
47:12
Speaker 1: possible to get energy out of a black hole? Once
47:14
Speaker 1: the answer is yes, the rest is up to the engineers.
47:17
Speaker 1: But I guess you know, to do this, you would
47:20
Speaker 1: need a lot of rocks, right, you would need a
47:21
Speaker 1: lot of You would need to build like giant rockets
47:25
Speaker 1: or something, or giant spaceships or giant like black hole
47:28
Speaker 1: the harvester devices or vehicles that you throw in and
47:32
Speaker 1: then they that know when to start coming out to
47:34
Speaker 1: on the other side, and that's your job. I guess
47:39
Speaker 1: to say, thanks for telling us that, but you're not
47:43
Speaker 1: telling us how to make it work. And our time
47:45
Speaker 1: is up. Thank you very much, Good luck. I'm gonna
47:49
Speaker 1: go make some homemade pasta lunch. No, but seriously, like,
47:53
Speaker 1: how practical is this idea? Right? Like you would need
47:56
Speaker 1: to come up with like some kind of spaceship that
47:59
Speaker 1: you throw into the black hole that then what then
48:03
Speaker 1: separates and then boost its way out and then you
48:07
Speaker 1: catch it on the other side. Yeah, so you need
48:09
Speaker 1: to develop some system, you know, where you have like
48:11
Speaker 1: explosive elements in rocks or rocks that split in half,
48:15
Speaker 1: or you know, somehow devise a way to do it
48:17
Speaker 1: with particle beams. But you know, in principle it is possible,
48:21
Speaker 1: all right. And so this idea is interesting because kind
48:25
Speaker 1: of where things are headed in the universe. We're heading
48:28
Speaker 1: towards sort of like an all black hole universe, right,
48:31
Speaker 1: Like eventually all of the black holes in the center
48:33
Speaker 1: of all those galaxies will eventually sort of consume all
48:36
Speaker 1: of those galaxies, and then they those clusters might also
48:40
Speaker 1: kind of crunched down to giant black holes. So We're
48:43
Speaker 1: going through a future where everything will be black holes, right,
48:46
Speaker 1: and so it might be good to know how to
48:48
Speaker 1: get energy out of the sons will continue to burn
48:51
Speaker 1: in this universe, and we do know that black holes
48:53
Speaker 1: will live on for billions and trillions of years, and
48:56
Speaker 1: so instead of just getting our energy from the nearest star,
48:59
Speaker 1: we might to learn how to get it from the
49:01
Speaker 1: nearest black hole. Right, But even then it's going to
49:04
Speaker 1: run out, right, Like, this is not a renewable resource,
49:06
Speaker 1: is it. Like once you take all the spin out
49:08
Speaker 1: of a black hole, it's kind of maybe useless to us,
49:11
Speaker 1: I suppose, But there are vast quantities of energy stored
49:14
Speaker 1: in these black holes, beyond even I think our capacity
49:17
Speaker 1: to charge our phones. I don't know. I wouldn't put
49:21
Speaker 1: it past humans to swipe their way into oblivion in
49:24
Speaker 1: the in trillions of years. All right, Well, an interesting
49:28
Speaker 1: idea and potentially maybe something that could propel humanity into
49:32
Speaker 1: the far far future. And just kind of another lesson
49:35
Speaker 1: about where the universe likes to hide energy, how it
49:39
Speaker 1: has all these crazy processes out there that are maybe
49:41
Speaker 1: storing vast amounts of potential energy. And we already know
49:45
Speaker 1: that the universe around us is very, very dense with energy.
49:49
Speaker 1: Every atom in your body contains an incredible amount of energy.
49:52
Speaker 1: Raisins worth of matter has more energy than a nuclear bomb.
49:57
Speaker 1: And so it's just a question of figuring out how
49:59
Speaker 1: to horror was that and how to do it safely? Yeah,
50:02
Speaker 1: I think I'll focus on the rhes fear first and
50:04
Speaker 1: the well, the more posture you eat, the larger the
50:07
Speaker 1: horhes fear gets. But then my head starts to spend
50:09
Speaker 1: and that creates these singularities or at least another jelly
50:13
Speaker 1: filled donut exactly the banana gularity. All right, well, we
50:16
Speaker 1: hope you enjoyed that. Thanks for joining us, see you
50:19
Speaker 1: next time. Thanks for listening, and remember that Daniel and
50:29
Speaker 1: Jorge Explain the Universe is a production of I Heart
50:32
Speaker 1: Radio or more podcast for my heart Radio, visit the
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50:39
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