Latest / Daniel and Kelly’s Extraordinary Universe / What does our black hole look like?

Transcript

What does our black hole look like? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, hooray, Today is Happy Astronomy Donut Day. Are they
• 0:13
  Speaker 1: giving away free donuts at every telescope? Yeah, you know,
• 0:18
  Speaker 1: today is the day that astronomers around the world get
• 0:21
  Speaker 1: together to gaze in awe at the picture of a doughnut. Man,
• 0:25
  Speaker 1: I need you physicist like snacks, but to dedicate a
• 0:28
  Speaker 1: whole day to that, it's just taking it to the
• 0:30
  Speaker 1: whole new level. Max. Donut jokes are pretty sweet. Yeah,
• 0:35
  Speaker 1: they really make your eyes glaze over there, like the
• 0:38
  Speaker 1: frosting on top of your breakfast. But what's so special
• 0:40
  Speaker 1: about this donut? Strangely enough, one of the weirdest things
• 0:44
  Speaker 1: in the universe looks like one of the most normal
• 0:47
  Speaker 1: everyday objects through a telescope. I'm not sure donuts an
• 0:51
  Speaker 1: everyday object. As you lead a very unhealthy lifestyle. Well,
• 0:56
  Speaker 1: maybe today's podcast will inspire you to start eating. What
• 0:59
  Speaker 1: are the like star flavored donuts? I don't know what
• 1:02
  Speaker 1: a star would taste like. Pretty brightly, I'm sure, little spicy.
• 1:05
  Speaker 1: Probably I'd like a doughnut covered in sparkles. Please. Hi'm
• 1:24
  Speaker 1: poor handmade cartoonists and the co author of Frequently Asked
• 1:27
  Speaker 1: Questions about the Universe. Hi, I'm Daniel, I'm a particle
• 1:30
  Speaker 1: physicist and a professor at U c Irvine, and it's
• 1:33
  Speaker 1: actually pretty rare that I eat a donut. Oh yeah,
• 1:36
  Speaker 1: rare because usually do other things with donuts. Yeah. I
• 1:39
  Speaker 1: usually build donut colliders and push them towards the speed
• 1:42
  Speaker 1: of left, just to see what happens. Oh man, I
• 1:45
  Speaker 1: do want to see what happens. Do they like morph
• 1:47
  Speaker 1: into a cronut or do they transform into he's a
• 1:51
  Speaker 1: veal or something? They actually get contracted into pancakes. Wow,
• 1:56
  Speaker 1: doughnut flavored pancakes. I think you've just blew everyone's mind
• 1:59
  Speaker 1: right now, because that's what pancakes need. They need to
• 2:01
  Speaker 1: be deep fried and even sweeter. Oh man, sounds like
• 2:04
  Speaker 1: the next hips through a trend. Donut pancakes or a
• 2:09
  Speaker 1: donut pancake sandwich. Mo Man, put some bacon on top,
• 2:13
  Speaker 1: and then you're done. Yeah, you're done for life. But anyways,
• 2:17
  Speaker 1: welcome to our podcast, Daniel and Jorge Explained the Universe,
• 2:20
  Speaker 1: a production of My Heart Radio in which we serve
• 2:23
  Speaker 1: up the most delicious breakfast ever, an intoxicating stack of
• 2:27
  Speaker 1: knowledge about the universe. Stuffed with mystery and cluelessness. We
• 2:31
  Speaker 1: chop up the biggest questions in the universe, from what's
• 2:34
  Speaker 1: going on at the center of our galaxy to how
• 2:36
  Speaker 1: did it all form? To how does it all make sense?
• 2:39
  Speaker 1: On the very smallest level, we don't shy away from
• 2:42
  Speaker 1: any of these questions, and we talk about them with
• 2:44
  Speaker 1: a healthy dose of silly dad jokes and a few
• 2:46
  Speaker 1: bites of a doughnut. Yeah, because it is a very
• 2:49
  Speaker 1: tasty and delicious universe, and we like to roll it
• 2:51
  Speaker 1: up here at the podcast, right up and dip it
• 2:54
  Speaker 1: in coffee in order to give you a big bite
• 2:56
  Speaker 1: of this amazing and incredible and awe inspiring cosmos. Do
• 3:00
  Speaker 1: you think physics needs a sweetener? That we need to
• 3:03
  Speaker 1: add comedy to physics to make it go down? In
• 3:05
  Speaker 1: physics like the medicine we're trying to get people to swallow.
• 3:08
  Speaker 1: I don't know how bitter are you? Then? Oh, I'm
• 3:14
  Speaker 1: mellowing in my old age. I'm no longer very cynical,
• 3:16
  Speaker 1: but I do feel like physics has this reputation of
• 3:19
  Speaker 1: being hard to understand or weird or intimidating or not
• 3:23
  Speaker 1: for everyone. And you know, that's one of the reasons
• 3:25
  Speaker 1: why we do this podcast is to try to make
• 3:27
  Speaker 1: sure everybody out there has access to these ideas and
• 3:30
  Speaker 1: can have fun thinking about them. Yeah, because technically everyone
• 3:34
  Speaker 1: is physics, right. I mean, we're sort of made out
• 3:36
  Speaker 1: of particles and put together by physics. And also physics
• 3:40
  Speaker 1: effects are everyday lives. Every day you wake up, you
• 3:43
  Speaker 1: are in a planet floating around in space, governed by
• 3:46
  Speaker 1: the laws of the universe. Assuming that there are laws
• 3:49
  Speaker 1: that we can figure out that humans are capable of
• 3:52
  Speaker 1: deriving these ideas that control the whole universe. It's a
• 3:57
  Speaker 1: pretty big notion. But we do our best to cast
• 3:59
  Speaker 1: our mind and out into the universe and try to
• 4:02
  Speaker 1: wrap it all up into our little brains, and we
• 4:04
  Speaker 1: have been doing our best. Humans have done an incredible
• 4:07
  Speaker 1: job of From our little perch here in this little
• 4:09
  Speaker 1: rock floating in a corner of the Milky Way, we've
• 4:11
  Speaker 1: been able to look out into the universe and period
• 4:14
  Speaker 1: the incredible things happening, and even deep within galaxies. That's
• 4:19
  Speaker 1: right through history, we've sort of expanded how far out
• 4:22
  Speaker 1: into the universe we've been able to see and our
• 4:24
  Speaker 1: sort of mental map about what's going on out there.
• 4:27
  Speaker 1: Remember that just a hundred years ago, we thought that
• 4:29
  Speaker 1: our galaxy was the only thing in the universe, and
• 4:31
  Speaker 1: now we can peer through all the stars in our
• 4:34
  Speaker 1: galaxy to see beyond it to other galaxies, to understand
• 4:37
  Speaker 1: the incredible depth of the cosmos, And we could also
• 4:41
  Speaker 1: look into the heart of our own galaxy to understand
• 4:44
  Speaker 1: what's going on at the center. Yeah, because while we've
• 4:47
  Speaker 1: been able to look out into the far reaches of
• 4:49
  Speaker 1: the observable universe, there is still a very big mystery
• 4:53
  Speaker 1: right here in the middle of our own neighborhood. That's right.
• 4:56
  Speaker 1: We sort of live in suburbia in our galaxy. We're
• 4:59
  Speaker 1: like twenty six thousand light years from the center of
• 5:02
  Speaker 1: the action, and we wonder, like, Hey, what's going on
• 5:06
  Speaker 1: down there? Is that part of the neighborhood totally different
• 5:09
  Speaker 1: from our part? Is there something crazy going on? Is
• 5:11
  Speaker 1: it just a bunch of stars? Yeah, I kind of
• 5:13
  Speaker 1: like living in the suburbs of the galaxy, you know.
• 5:16
  Speaker 1: I think as you get older, you're like, oh, I
• 5:18
  Speaker 1: like living in this small town where you can say
• 5:21
  Speaker 1: hi to people in the street and walk your dog
• 5:23
  Speaker 1: if you have a dog. Well, it's definitely a lot
• 5:24
  Speaker 1: more habitable. If we were closer to the center of
• 5:27
  Speaker 1: the galaxy, that would be incredibly intense radiation, and so
• 5:31
  Speaker 1: life as we know it would be pretty different. Everyone
• 5:34
  Speaker 1: would have a nicer tense I guess. And on the
• 5:37
  Speaker 1: far outskirts of the galaxy there aren't as many heavy
• 5:40
  Speaker 1: metals perform interesting chemistry. So right now we're living in
• 5:42
  Speaker 1: sort of the perfect slice of the galaxy for our
• 5:45
  Speaker 1: kind of life at least to evolve. Yeah, it's a
• 5:48
  Speaker 1: pretty good place to raise a family, I guess, is
• 5:49
  Speaker 1: what we're saying. And the schools are pretty good too,
• 5:52
  Speaker 1: and the donuts are pretty tasty. Well, speaking of donuts,
• 5:56
  Speaker 1: recently there has been a big news event about very
• 6:00
  Speaker 1: interesting and very heavy discovery right here in our galaxy.
• 6:04
  Speaker 1: That's right. We have been wondering for a long time
• 6:06
  Speaker 1: what exactly is going on at the center of our galaxy,
• 6:10
  Speaker 1: But it's very hard to see precisely because between us
• 6:13
  Speaker 1: and the center of the galaxy is a lot of
• 6:15
  Speaker 1: gas and dust and other things obscuring our view. And
• 6:19
  Speaker 1: so while we've been able to get hints about what
• 6:22
  Speaker 1: might be happening at the center, is there a black hole?
• 6:24
  Speaker 1: How big is it? How small is it? Until very
• 6:27
  Speaker 1: recently we haven't been a hud sure what's there? Not
• 6:31
  Speaker 1: until at least we trained a special Earth sized telescope
• 6:35
  Speaker 1: to take a picture of it. So today on the podcast,
• 6:37
  Speaker 1: we'll be tackling the question what is the center of
• 6:45
  Speaker 1: our galaxy? Or what does a black hole in the
• 6:49
  Speaker 1: center of our galaxy look like? And what would it
• 6:51
  Speaker 1: taste like if you took a huge bite out of
• 6:54
  Speaker 1: that cosmic donut? Oh man, I'd probably be very fattening.
• 6:57
  Speaker 1: You know, it's very dense with calories. It would be
• 7:00
  Speaker 1: a massive, massive undertaking. You probably would need to eat
• 7:03
  Speaker 1: for the rest of your life or be able to
• 7:06
  Speaker 1: eat anything for the rest of your life. Would be
• 7:08
  Speaker 1: the last thing you would eat. And so you've probably
• 7:10
  Speaker 1: seen by now what this picture looks like, because it
• 7:12
  Speaker 1: came out very recently and there was a lot of
• 7:14
  Speaker 1: science headlines and a lot of news about this. Everybody
• 7:17
  Speaker 1: was very excited. And if you haven't seen it, then
• 7:19
  Speaker 1: essentially it looks like a black image with a glowing
• 7:22
  Speaker 1: orange ring on it, something like a big fat glaze donut.
• 7:26
  Speaker 1: What if the glaze made out of danue particles going
• 7:29
  Speaker 1: at the speed of light close to the speed of light,
• 7:32
  Speaker 1: sparkly electron frosting. I have no idea, but yeah, this
• 7:35
  Speaker 1: was pretty big news because I guess it's the first
• 7:37
  Speaker 1: time we get a picture of the black hole at
• 7:39
  Speaker 1: the center of our galaxy, because before we just thought
• 7:42
  Speaker 1: it was there, or we saw evidence that it was there,
• 7:44
  Speaker 1: but it could have been there, could have been something
• 7:46
  Speaker 1: else in the middle there. That's right. We had sort
• 7:48
  Speaker 1: of indirect evidence of the existence of that black hole,
• 7:51
  Speaker 1: and we actually talked on the podcast once about how
• 7:53
  Speaker 1: it might be something else, some weird darky no matter.
• 7:56
  Speaker 1: And recently scientists have developed a technique to take these
• 7:59
  Speaker 1: picture to train a bunch of telescopes all around the Earth,
• 8:02
  Speaker 1: and they did this a few years ago for another
• 8:04
  Speaker 1: black hole M eight seven and released the first picture
• 8:08
  Speaker 1: ever of a black hole, and now they've done the
• 8:10
  Speaker 1: same for our galaxy. Yeah, it's kind of funny that
• 8:13
  Speaker 1: with the first picture of a black hole we've ever
• 8:15
  Speaker 1: gotten as a human species was from another galaxy. Right, Like,
• 8:18
  Speaker 1: we have a black hole right here in our house,
• 8:20
  Speaker 1: in our neighborhood, but the first one we took a
• 8:22
  Speaker 1: picture of was somebody else's black hole. Well, our black
• 8:25
  Speaker 1: holes actually harder to see than the one in the
• 8:28
  Speaker 1: neighboring galaxy. It's sort of like, you know, if you're
• 8:30
  Speaker 1: in your own house, it's harder to see what's on
• 8:33
  Speaker 1: your roof because you've got to look through the house.
• 8:35
  Speaker 1: But if you look out your window, you can see
• 8:37
  Speaker 1: what's on your neighbor's roof pretty easily. And so the
• 8:40
  Speaker 1: neighboring galaxies black hole is actually easier to spot than
• 8:43
  Speaker 1: the one in our own galaxy because of all the
• 8:45
  Speaker 1: stuff between us and the center of the galaxy. I see.
• 8:48
  Speaker 1: So if your neighbor's kids post for pictures more easily
• 8:51
  Speaker 1: than your kids, that's what you would take a picture
• 8:53
  Speaker 1: of them hanging out around your house. No, nobody. If
• 8:56
  Speaker 1: I had just invented the camera, I might test it
• 8:58
  Speaker 1: out on the neighbor's kids first before I take pictures
• 9:01
  Speaker 1: in my own in case it camera does something to
• 9:04
  Speaker 1: its subjects. Oops. I didn't realize I built a death
• 9:07
  Speaker 1: ray into my camera. Sorry guys, Sorry neighbor. But yeah,
• 9:11
  Speaker 1: it was pretty big news. It was on the headlines
• 9:14
  Speaker 1: of the Science news and people were pretty excited about it. Right,
• 9:17
  Speaker 1: It's like, you know, this is like our black hole.
• 9:19
  Speaker 1: People were calling it our black hole. I think it
• 9:21
  Speaker 1: was a hashtag on Twitter. Yeah, the scientists are very excited.
• 9:24
  Speaker 1: Some of them have been working on this black hole
• 9:26
  Speaker 1: for decades. One of them said, I've thought about Sagittarius
• 9:29
  Speaker 1: a star for a long time, twenty two years ago
• 9:32
  Speaker 1: with my first paper on this black hole. So seeing
• 9:35
  Speaker 1: the picture was like online chatting for years and then
• 9:37
  Speaker 1: finally meeting in person and realizing, wow, you're real. Yeah,
• 9:43
  Speaker 1: and uh, we'll find out if he or she was
• 9:45
  Speaker 1: disappointed or not exactly. But it was a big event
• 9:48
  Speaker 1: in science at least, And so I was wondering, you know,
• 9:51
  Speaker 1: I had people heard about this, had this penetrated into
• 9:53
  Speaker 1: the life of the everyday person. Yeah, So, as usual,
• 9:56
  Speaker 1: Daniel went out there into the world to ask people
• 9:58
  Speaker 1: walking on the street if they had seen the new
• 10:01
  Speaker 1: pictures of our black hole and if they knew what
• 10:03
  Speaker 1: it might look like. But the news juice came out
• 10:06
  Speaker 1: just yesterday, right, Daniel, So that the just run out
• 10:08
  Speaker 1: of your office right away to record people. I did.
• 10:11
  Speaker 1: I was curious whether you see I undergrad I have
• 10:14
  Speaker 1: their finger on the pulse of the science news, or
• 10:16
  Speaker 1: whether they had no idea what I'm talking about. To
• 10:19
  Speaker 1: think about it for a second, where were you when
• 10:22
  Speaker 1: they polished the first pictures of our milky waist black hole?
• 10:25
  Speaker 1: Here's what people had to say. Have you seen the
• 10:27
  Speaker 1: latest picture of the black hole at the center of
• 10:29
  Speaker 1: our galaxy? No? I have not. What do you imagine
• 10:33
  Speaker 1: that it might look like? Um, very empty in the center,
• 10:39
  Speaker 1: but surrounded by what may look white and black around
• 10:42
  Speaker 1: the surface. Have you seen the latest picture of the
• 10:44
  Speaker 1: black hole at the center of our galaxy? No? What
• 10:49
  Speaker 1: do you imagine a black hole might look like if
• 10:50
  Speaker 1: you could take a picture of it? Um, like a
• 10:54
  Speaker 1: big amorphous mass with like stars and planets in it. Yeah.
• 11:01
  Speaker 1: What do you think we might learn from taking a
• 11:02
  Speaker 1: picture of Why the scientists want to take a picture
• 11:05
  Speaker 1: of a black hole like for measuring? I didn't think
• 11:08
  Speaker 1: that black hole will look like that. What do you
• 11:10
  Speaker 1: think it would look? Just a whole with nothing around it?
• 11:14
  Speaker 1: So what do you think we've learned from this picture?
• 11:19
  Speaker 1: Something that no one who had have thought of it
• 11:23
  Speaker 1: would just shine some lights that it would help other
• 11:27
  Speaker 1: people to learn something on top of what we have
• 11:31
  Speaker 1: learned from this new picture. I guess what does the
• 11:34
  Speaker 1: black hole look like? Um? I feel like because space
• 11:39
  Speaker 1: is really dark and just be mostly black. But since
• 11:43
  Speaker 1: they're probably using like raise or something to try to
• 11:46
  Speaker 1: like figure it out, maybe like in the photo there's
• 11:49
  Speaker 1: like some like orange even like black in the middle
• 11:51
  Speaker 1: or something. And what do you think we learned from
• 11:53
  Speaker 1: taking such a picture? Why do scientists do it? I
• 11:56
  Speaker 1: think it's good to have in your records and study
• 12:00
  Speaker 1: out like how far we can go and like have
• 12:03
  Speaker 1: tangible evidence and use that kind of what we already
• 12:06
  Speaker 1: had in mind, which is what it actually looks like.
• 12:09
  Speaker 1: What do you think a black hole might look like?
• 12:11
  Speaker 1: In your imagination you took a picture of what would
• 12:13
  Speaker 1: you see? Black? Black and stars? I feel like yet
• 12:19
  Speaker 1: very bright blowing because it's supposed to be like an explosion, right,
• 12:23
  Speaker 1: it's like starts, so I feel like very sparkly. Yeah, colorful.
• 12:27
  Speaker 1: I would think you'ld be the opposite of what it's called,
• 12:31
  Speaker 1: because scientists are not good at naming things. Yeah, I
• 12:33
  Speaker 1: feel like dark because I feel like isn't black the
• 12:36
  Speaker 1: most dominant color? And black holes kind of absorbed everything.
• 12:39
  Speaker 1: I feel like it'd be dark in the senter and
• 12:40
  Speaker 1: then sparkly on the outside, like with everything that's consuming. Yeah,
• 12:43
  Speaker 1: what do you think a black hole would look like?
• 12:45
  Speaker 1: If you could take a picture of a black hole?
• 12:47
  Speaker 1: To me, like in a galaxy in the in space.
• 12:50
  Speaker 1: It's like a hole in space. It's like like if
• 12:53
  Speaker 1: you're looking at like water draining, That's what I would
• 12:55
  Speaker 1: imagine it looks like. But like a black form of
• 12:59
  Speaker 1: mass I us is what I would imagine it would
• 13:01
  Speaker 1: look like. I don't think I've actually looked at a
• 13:03
  Speaker 1: photo of a black hole. What do you think scientists
• 13:06
  Speaker 1: learned from taking this picture? Like? Why do they do it?
• 13:09
  Speaker 1: I mean, I think it's also an issue of if
• 13:13
  Speaker 1: a major mass black hole forms, it's sucking us in
• 13:17
  Speaker 1: and then potentially causing catastrophe in that sense and kind
• 13:20
  Speaker 1: of preventing I guess the world domination of black holeness. Yeah,
• 13:29
  Speaker 1: I personally would not want to be sucked into a
• 13:30
  Speaker 1: black hole. I feel like you've got a lot of
• 13:32
  Speaker 1: white guy answers here, Like the presumer said, it just
• 13:35
  Speaker 1: looks like a whole a whole lot of nothing. Well,
• 13:38
  Speaker 1: almost nobody had actually seen this picture already. They're not
• 13:42
  Speaker 1: like desperately tuned to science news the way I guess
• 13:45
  Speaker 1: physics professors are. But I asked them to speculate what
• 13:48
  Speaker 1: they thought a black hole might look like, and they
• 13:50
  Speaker 1: came up with some pretty creative answers. Yeah, creative and accurate, tod.
• 13:54
  Speaker 1: I mean it does look just like a whole. A
• 13:55
  Speaker 1: black hole does like like oh yeah. And the girl
• 13:59
  Speaker 1: who said, you know, maybe a hole with a bunch
• 14:01
  Speaker 1: of sparkly stuff around it. I showed her the picture
• 14:04
  Speaker 1: later and she was like, wow, I should switch to
• 14:05
  Speaker 1: being a physics major. Hey, yeah, or psychic reading or something.
• 14:11
  Speaker 1: I was sending her the answers with my mind. Yeah.
• 14:14
  Speaker 1: And somebody else said, it just looks black, mostly black,
• 14:17
  Speaker 1: but mostly black. What would the other not not black?
• 14:20
  Speaker 1: There's so many shades of black, man, you can't just
• 14:22
  Speaker 1: order black paint. If you go into the paint store.
• 14:24
  Speaker 1: There's like black Hole black. There's Matt black, there's Zen black.
• 14:28
  Speaker 1: You know, I see. Yeah, you gotta choose your paint
• 14:31
  Speaker 1: colors carefully. They might absorb all of your house or something.
• 14:35
  Speaker 1: You picked the wrong one. But he has some pretty
• 14:37
  Speaker 1: big news, and so I guess a lot of people
• 14:38
  Speaker 1: are wondering, what is this discovery about, how did we
• 14:41
  Speaker 1: actually take a picture of this black hole? And what
• 14:44
  Speaker 1: does it mean about what we understand about our galaxy.
• 14:46
  Speaker 1: It's actually kind of a big moment in understanding something
• 14:49
  Speaker 1: about black holes and in understanding the nature of our
• 14:53
  Speaker 1: own galaxy. So even though this just looks like a
• 14:55
  Speaker 1: big donut and it sort of looks like the last
• 14:57
  Speaker 1: donut we saw, we really did learn fascinating facts about
• 15:01
  Speaker 1: our own neighborhood. Another donut is never just another donut, Daniel.
• 15:05
  Speaker 1: You know you're hooked. Once you have one donut, You're
• 15:07
  Speaker 1: like always thinking about that next donut. And these scientists
• 15:10
  Speaker 1: are no different. They're just people a glaze it with
• 15:13
  Speaker 1: some addictive drug with knowledge. All right, well we'll step
• 15:16
  Speaker 1: people through this discovery, and I guess we'll start with
• 15:19
  Speaker 1: the basics. What is a black hole? And what are
• 15:21
  Speaker 1: some of the things we still don't know about black holes? Right? So,
• 15:24
  Speaker 1: black holes are these weird locations in space where there
• 15:27
  Speaker 1: is so much stuff crammed into a small area that
• 15:31
  Speaker 1: the gravity is so intense, The curvature of space is
• 15:34
  Speaker 1: so intense that there's a trapping region, an event horizon,
• 15:38
  Speaker 1: a sphere within which if you fall into it, you
• 15:40
  Speaker 1: cannot escape. No information can ever leave the event horizon
• 15:44
  Speaker 1: because space has been so strongly within that event horizon
• 15:47
  Speaker 1: that it becomes one directional. Every path leads towards the
• 15:52
  Speaker 1: center of the black hole. No matter what direction you
• 15:54
  Speaker 1: shoot a photon, it will always end up at the singularity.
• 15:58
  Speaker 1: So black holes are these strange of it's in space,
• 16:01
  Speaker 1: originally predicted by Einstein's theory of general relativity and then
• 16:04
  Speaker 1: actually seeing out there in the universe. Black holes are
• 16:07
  Speaker 1: not theoretical. We are certain that they are out there,
• 16:11
  Speaker 1: and some of them form when stars collapse at the
• 16:14
  Speaker 1: end of their life cycle and they can no longer
• 16:15
  Speaker 1: resist the pressure of gravity, squeezing them down into a
• 16:19
  Speaker 1: dense spot. And there are also black holes at the
• 16:21
  Speaker 1: centers of many galaxies. Yeah. One thing that's interesting about
• 16:24
  Speaker 1: black holes is that they come in many sizes, right, Like,
• 16:27
  Speaker 1: you're gonna have a tiny little black hole the size
• 16:29
  Speaker 1: of your pinky finger, and you can have one the
• 16:31
  Speaker 1: size of like ten bazillion sons, right, that's right. The
• 16:34
  Speaker 1: key thing is the density. You can take almost any
• 16:36
  Speaker 1: amount of mass and make it into a black hole
• 16:38
  Speaker 1: if you squeeze it down to a small enough radius,
• 16:41
  Speaker 1: because then space gets curved because remember that gravity falls
• 16:45
  Speaker 1: rapidly with distance. So if you have like a large
• 16:47
  Speaker 1: object like the Earth, you're pretty far from the center
• 16:50
  Speaker 1: of the Earth, essentially where the gravitational power comes from.
• 16:53
  Speaker 1: But if you squeeze the Earth down to the size
• 16:55
  Speaker 1: of a peanut, then you're getting much closer to all
• 16:57
  Speaker 1: that mass, and so the gravity is much much stronger,
• 17:00
  Speaker 1: and a peanut sized earth mask could actually form a
• 17:03
  Speaker 1: black hole. Black Holes come in a huge variety of sizes,
• 17:06
  Speaker 1: some of the millions or billions of times the mass
• 17:09
  Speaker 1: of our Sun. Yeah, it's pretty amazing. And most of
• 17:12
  Speaker 1: the big ones, I guess, are in the middle of galaxies.
• 17:15
  Speaker 1: And I guess the question that I knows how do
• 17:16
  Speaker 1: we know this, Like, how do we know galaxies have
• 17:18
  Speaker 1: supermassive black holes in the middle of them? Yeah, we
• 17:21
  Speaker 1: think that galaxies form with black holes at the hearts
• 17:23
  Speaker 1: of them. And until we had that picture of the
• 17:26
  Speaker 1: black hole in might s, we were in a sure
• 17:29
  Speaker 1: that they really were black holes. We have sort of
• 17:31
  Speaker 1: indirect evidence for the black hole because again, you can
• 17:34
  Speaker 1: never see a black hole directly because it doesn't give
• 17:37
  Speaker 1: off light, it doesn't reflect light, it absorbs all light.
• 17:40
  Speaker 1: So what we've seen before we saw these pictures were
• 17:42
  Speaker 1: just like stars orbiting around some location in space that
• 17:46
  Speaker 1: seemed to have very strong gravity, and we can do
• 17:49
  Speaker 1: calculations to think, like, well, what could be that small
• 17:53
  Speaker 1: and have that much gravity, and the only thing that
• 17:55
  Speaker 1: fit the bill was a black hole. It's sort of
• 17:58
  Speaker 1: like we've seen the trapick around the black hole, but
• 18:01
  Speaker 1: we had never seen, at least until a few years ago,
• 18:03
  Speaker 1: an actual picture of a black hole. That's right, and
• 18:06
  Speaker 1: a purist might say that we haven't even still proven
• 18:09
  Speaker 1: that black holes exist, because in the end, what we're
• 18:12
  Speaker 1: doing is always taking pictures of the traffic around the
• 18:14
  Speaker 1: black hole. Until recently, we were doing things like looking
• 18:17
  Speaker 1: at stars that were whizzing near the black hole, but
• 18:20
  Speaker 1: not getting even that close. What these pictures allow us
• 18:23
  Speaker 1: to do is to look even closer. Basically, they're taking
• 18:25
  Speaker 1: pictures of the stuff immediately around the black hole rather
• 18:29
  Speaker 1: than stars in sort of a more distant orbit. So
• 18:32
  Speaker 1: it gives us a better way to understand how small
• 18:34
  Speaker 1: it has to be, and that makes it more likely
• 18:37
  Speaker 1: to be a black hole. But still we're never a
• 18:40
  Speaker 1: sure because all of these things are always indirect I see, well,
• 18:44
  Speaker 1: I guess philosophically, it's impossible to take a picture of
• 18:47
  Speaker 1: a black hole, right, Like when you take a picture
• 18:49
  Speaker 1: of something, you're taking you're capturing the photons that bounce
• 18:51
  Speaker 1: off of something like your kids or you're taking. You're
• 18:55
  Speaker 1: capturing the photons that come off of a star. But
• 18:57
  Speaker 1: a black hole like literally doesn't by definition, doesn't admit anything.
• 19:00
  Speaker 1: So it's it's actually technically impossible to take a picture
• 19:04
  Speaker 1: of a black hole. It's technically impossible to see a
• 19:07
  Speaker 1: photon that has been within the event horizon. You could
• 19:09
  Speaker 1: see photons do things like orbit a black hole right,
• 19:13
  Speaker 1: move in a circle around a black hole, and from
• 19:16
  Speaker 1: that you could argue that there has to be something
• 19:18
  Speaker 1: there with incredible mass and a small radius. And then
• 19:21
  Speaker 1: you know, there's one more leap to say only black
• 19:24
  Speaker 1: holes could do that, And that's a leap because you
• 19:26
  Speaker 1: know that's our theory of physics. Maybe somebody else one
• 19:28
  Speaker 1: day will come up with another idea for what could
• 19:30
  Speaker 1: be there. We talked once in the podcast about the
• 19:32
  Speaker 1: idea of dark stars. Maybe black holes are not actually
• 19:35
  Speaker 1: black holes. They're just very slowly collapsing stars that are
• 19:39
  Speaker 1: going to bounce back eventually one day. So in principle,
• 19:42
  Speaker 1: you're right, you can never take a direct picture of
• 19:45
  Speaker 1: this object. You always have to use some physics idea,
• 19:48
  Speaker 1: some model to interpret the indirect information you gather from
• 19:51
  Speaker 1: what's happening in the very close vicinity. The name of
• 19:54
  Speaker 1: the game is to get as close as you can
• 19:56
  Speaker 1: to narrow down the spectrum of options. Right, right, And
• 19:59
  Speaker 1: do you volunteered get close to a black hole to
• 20:02
  Speaker 1: take a picture. I volunteered to receive ten billion dollars
• 20:04
  Speaker 1: from the government to build a telescope that lets me
• 20:07
  Speaker 1: take pictures of photons that went very close to the
• 20:09
  Speaker 1: black hole. So yes, thank you very much. Several levels
• 20:13
  Speaker 1: removed there, Just add the donuts to like, get why
• 20:15
  Speaker 1: did you get paid in donuts? Why don't we put
• 20:17
  Speaker 1: donuts in orbit around the black hole? That would be
• 20:20
  Speaker 1: pretty awesome, you know, just like shoot a series of donuts.
• 20:23
  Speaker 1: That sounds like an enormous waste of taxpayers dollars. Wouldn't
• 20:27
  Speaker 1: you like to see a black hole tear a part
• 20:28
  Speaker 1: of donut? I mean, come on, you would watch that video.
• 20:30
  Speaker 1: If I had a video right now of a black
• 20:32
  Speaker 1: hole spaghettifying a donut, you would watch it. It sounds
• 20:36
  Speaker 1: like a tragedy, donil. There's so many other things you
• 20:39
  Speaker 1: could throw at a black hole to see it gets spaghettified.
• 20:42
  Speaker 1: Why a donut? Well, that gives me another idea for
• 20:44
  Speaker 1: a terrible dish pasta made out of donuts. Has anybody
• 20:48
  Speaker 1: ever done that? Donuts spaghetti, donuts spaghetti? Yeah, interesting, it's
• 20:52
  Speaker 1: a donut made out of spaghetti, or spaghetti made out
• 20:55
  Speaker 1: of donuts, Spaghetti made out of donuts. Like, what would
• 20:57
  Speaker 1: happen if you threw a donut near a black hole?
• 20:59
  Speaker 1: It would get it spaghettified. So we're just doing that
• 21:02
  Speaker 1: for you and serving it up and charging you fifty bucks.
• 21:05
  Speaker 1: We'll add that to the many of our physics. The
• 21:07
  Speaker 1: restaurants that we talked about last time. Somebody's working on that, right.
• 21:11
  Speaker 1: We have somebody on that right, and we have people
• 21:14
  Speaker 1: our manager is looking into the business model for that.
• 21:17
  Speaker 1: I'm sure they're getting investors ready. But we study black
• 21:19
  Speaker 1: holes not just by looking at the stars in orbit
• 21:21
  Speaker 1: around them, but also by looking at their emissions. The
• 21:25
  Speaker 1: stuff that's closer to the black hole than actual stars
• 21:28
  Speaker 1: is this accretion disc and it's filled with gas that's
• 21:30
  Speaker 1: really really hot and giving off all sorts of particles
• 21:33
  Speaker 1: and X rays. Some of these guys that made very
• 21:35
  Speaker 1: very bright beams of light sort of up and down
• 21:38
  Speaker 1: along their spin axcess and these are called quasars, and
• 21:41
  Speaker 1: quasars are actually the reason that we believed black holes
• 21:44
  Speaker 1: exist in the first place. We saw these very bright
• 21:46
  Speaker 1: beams of light and we couldn't understand what else could
• 21:49
  Speaker 1: be making them, these very distant, very bright beams from
• 21:52
  Speaker 1: the early universe, until people understood, oh, maybe a black
• 21:56
  Speaker 1: hole accretion disc was powering this radiation. Interesting, that's the
• 22:00
  Speaker 1: only thing that could explain a quasar like. It couldn't
• 22:02
  Speaker 1: be a dark star or some other interesting, maybe new
• 22:05
  Speaker 1: physics object in the middle there. It had to be
• 22:07
  Speaker 1: black holes. The idea of dark stars hadn't been born
• 22:10
  Speaker 1: yet when people were discovering black holes in the sixties
• 22:13
  Speaker 1: or seventies, so it's sort of like anything in that
• 22:15
  Speaker 1: category had to be something that small and that dense.
• 22:19
  Speaker 1: People didn't realize that that was actually something out there
• 22:22
  Speaker 1: in the universe. They thought black holes were like a
• 22:24
  Speaker 1: theoretical concept, not something that would ever actually form, And
• 22:28
  Speaker 1: when they saw these quasars, they realized something needed to
• 22:30
  Speaker 1: be really incredibly gravitationally powerful in order to create these quasars. So, yeah,
• 22:35
  Speaker 1: you're right, it could be that dark stars are at
• 22:38
  Speaker 1: the heart of every galaxy or something else weirder, some
• 22:41
  Speaker 1: quantum gravity theory that's even stranger, but it had to
• 22:44
  Speaker 1: be something very small and very compact and very dense.
• 22:48
  Speaker 1: I feel like should work for Marvel there. That sounded
• 22:51
  Speaker 1: like a very exciting movie. So there is a black
• 22:53
  Speaker 1: hole in the middle of our galaxy, and I guess,
• 22:55
  Speaker 1: thankfully it's not a quaser, right, because if it was
• 22:57
  Speaker 1: a quasar, we might be fried. Right, that's right. We're
• 23:00
  Speaker 1: glad actually that that black hole is not a quasar.
• 23:03
  Speaker 1: These quazars don't emit in every direction. They tend to
• 23:05
  Speaker 1: admit sort of up and down along their spin access.
• 23:08
  Speaker 1: So it depends on where that quasar is pointed, where
• 23:11
  Speaker 1: the black hole is pointed. But it would be dangerous
• 23:14
  Speaker 1: if it was a quasar, could be like sweeping out
• 23:16
  Speaker 1: through the universe or sweeping out through the Milky Way.
• 23:19
  Speaker 1: But we didn't know a lot about this black hole already.
• 23:21
  Speaker 1: There was a Nobel Prize given recently do a couple
• 23:24
  Speaker 1: of folks for studying the motion of stars in the
• 23:27
  Speaker 1: vicinity of the black hole, which is really very strong
• 23:30
  Speaker 1: evidence for the black hole. Interesting. So there is a
• 23:33
  Speaker 1: black hole in the middle of our gaxy, and we
• 23:35
  Speaker 1: know some things about it, but we don't know everything
• 23:38
  Speaker 1: about it. And we also don't know a lot about
• 23:40
  Speaker 1: black holes in the middle of galaxies, how they get
• 23:42
  Speaker 1: so big, and so let's get into the discovery that's
• 23:45
  Speaker 1: made the news recently, and let's talk about the big
• 23:47
  Speaker 1: black hole don't. But first let's take a quick break.
• 24:02
  Speaker 1: All right, Daniel, we are putting together the many of
• 24:05
  Speaker 1: our physics, them the restaurant, and there's I guess for dessert,
• 24:08
  Speaker 1: They're going to be black hole donuts or black donut holes.
• 24:12
  Speaker 1: I think everything should be made out of donuts. You're
• 24:14
  Speaker 1: in a cup of coffee. We took some donuts and
• 24:16
  Speaker 1: we somehow turned it into coffee. You sort of donut juice,
• 24:19
  Speaker 1: donut pancakes, donut spaghetti, don't ut bananas. We might need
• 24:23
  Speaker 1: a biologist for that one. We need another billion years
• 24:26
  Speaker 1: of evolution. Yeah, but it's kind of interesting that we
• 24:28
  Speaker 1: took this picture of a black hole in the middle
• 24:30
  Speaker 1: of our galaxy and everyone started calling you the donut.
• 24:33
  Speaker 1: It was like really popular to use the word donut.
• 24:35
  Speaker 1: That's right. And Crispy Cream the company even got into
• 24:38
  Speaker 1: the game and they are today giving away free donuts.
• 24:41
  Speaker 1: You go into a Crispy Cream today, you can get
• 24:42
  Speaker 1: one free glazed donut in honor of this discovery. Wow,
• 24:46
  Speaker 1: that's amazing, and unfortunately I live far from a Crispy
• 24:49
  Speaker 1: Cream but the Daniel, have you gone in your crispy
• 24:51
  Speaker 1: cream donut yet? No? I have. Don't you want to celebrate?
• 24:54
  Speaker 1: I'm going to celebrate as soon as we finished this podcast,
• 24:57
  Speaker 1: So let's get onto it all right. Well, so there's
• 24:59
  Speaker 1: been a picture taking of the black hole in the
• 25:00
  Speaker 1: middle of our galaxy, and it's interesting because it's sort
• 25:04
  Speaker 1: of confirms that it's there, right, like we sort of
• 25:07
  Speaker 1: before I thought it was there. I knew a lot
• 25:09
  Speaker 1: about what was going on there, but we weren't sure
• 25:12
  Speaker 1: there was a black hole. That's right, And let's be
• 25:14
  Speaker 1: specific about what we knew and what we didn't know,
• 25:16
  Speaker 1: and then what we've learned today, because I think it's
• 25:19
  Speaker 1: really quite interesting. What we knew already was the mass
• 25:22
  Speaker 1: of the black hole. We knew that it was four
• 25:25
  Speaker 1: million times the mass of the Sun, and we can
• 25:28
  Speaker 1: measure that because we can look at its gravitational impact
• 25:31
  Speaker 1: on stars nearby. We can calculate the strength of gravity,
• 25:35
  Speaker 1: and we know the distance and we can see stars
• 25:37
  Speaker 1: whizzing around this black hole, so it's not hard to
• 25:40
  Speaker 1: figure out how massive it has to be to explain
• 25:43
  Speaker 1: all the stuff moving around it. The question that remains
• 25:46
  Speaker 1: is how big is it? In order to figure out
• 25:48
  Speaker 1: how big it is is harder because you know, a
• 25:50
  Speaker 1: big object than a small object with the same mass
• 25:53
  Speaker 1: have the same gravitational effect. So you can't tell the
• 25:56
  Speaker 1: size of this thing just by looking at how the
• 25:58
  Speaker 1: stars moved. Have to look and see what comes close
• 26:01
  Speaker 1: to the black hole. Well, I guess maybe help me
• 26:04
  Speaker 1: understand here. I feel like you're saying that we could
• 26:07
  Speaker 1: see the stars going around the black hole, but somehow
• 26:10
  Speaker 1: we couldn't see the black hole itself, Like I know,
• 26:12
  Speaker 1: it's in the middle of the galaxy and there's a
• 26:14
  Speaker 1: lot going on there and it's kind of hard to
• 26:16
  Speaker 1: see in there. But we could still see sort of
• 26:18
  Speaker 1: the stars that are very close to the black hole, right,
• 26:21
  Speaker 1: like those who can see right with regular telescopes. That's right.
• 26:23
  Speaker 1: So we're looking at the center of the galaxy with
• 26:26
  Speaker 1: different kinds of eyeballs because the center of the galaxy
• 26:28
  Speaker 1: is clouded with gas and with dust, so in order
• 26:31
  Speaker 1: to see stuff you have to use special kinds of telescopes.
• 26:34
  Speaker 1: We can see the stars, for example, they shine through
• 26:36
  Speaker 1: the gas of the dust, especially in the infrared. So
• 26:39
  Speaker 1: we can use the infrared to see these stars, and
• 26:41
  Speaker 1: so we can track the path of these stars and
• 26:43
  Speaker 1: see as they move around, and that tells us sort
• 26:46
  Speaker 1: of where the black hole should be, and it tells
• 26:49
  Speaker 1: us how massive it is. But I see the stars
• 26:52
  Speaker 1: sort of shine through all that stuff that's in the
• 26:55
  Speaker 1: middle of the galaxy. But I guess the black hole
• 26:57
  Speaker 1: doesn't shine through, right, because it's a black hole. And
• 27:01
  Speaker 1: it's also super duper duper small, right, So the kind
• 27:05
  Speaker 1: of thing that we're looking for is really really tiny.
• 27:08
  Speaker 1: It's like if you were trying to take a picture
• 27:09
  Speaker 1: of a doughnut that was on the surface of the Moon.
• 27:12
  Speaker 1: So you need a very very powerful camera in order
• 27:15
  Speaker 1: to see the stuff that's right around the black hole. Wait, what, like,
• 27:19
  Speaker 1: the equivalent size of the black hole in the middle
• 27:22
  Speaker 1: of our galaxy is the same as trying to see
• 27:25
  Speaker 1: a donut on the moon. Yeah, if you put a
• 27:27
  Speaker 1: donut on the surface of the Moon and try to
• 27:28
  Speaker 1: take a picture of it. Another analogy is that if
• 27:31
  Speaker 1: you were sitting in Munich in Germany and you were
• 27:33
  Speaker 1: trying to take a picture of bubbles in a glass
• 27:36
  Speaker 1: of beer. In New York City, like it's a big object,
• 27:38
  Speaker 1: but it's incredibly far away. The center of the galaxy
• 27:41
  Speaker 1: is twenty six thousand light years away, and this thing
• 27:44
  Speaker 1: doesn't emit a lot of light, right, it's black, and
• 27:47
  Speaker 1: so trying to take a picture of stuff around this
• 27:49
  Speaker 1: and also see the hole in the middle of it.
• 27:52
  Speaker 1: So it's a very very challenging problem, right, it's super
• 27:55
  Speaker 1: far away. And also, I mean it's not that big
• 27:58
  Speaker 1: cosmically speaking, right, I mean you might even think that
• 28:02
  Speaker 1: a black hole as being this huge thing, but and
• 28:04
  Speaker 1: it is four million times the massive our Sun. But
• 28:06
  Speaker 1: in terms of size, like four million times the mass
• 28:08
  Speaker 1: of our Sun, for a black hole is not like
• 28:10
  Speaker 1: one of those super giant ones you see out there
• 28:13
  Speaker 1: in other galaxies. That's right. The other black hole that
• 28:15
  Speaker 1: we took a picture of previously M eight seven is
• 28:18
  Speaker 1: more than a thousand times as massive, so it's like
• 28:22
  Speaker 1: six and a half billion times the mass of the Sun,
• 28:25
  Speaker 1: which made it much much bigger. So even though the
• 28:28
  Speaker 1: previous black hole that we saw M eight seven is
• 28:31
  Speaker 1: much bigger and much more massive, was also much further away.
• 28:34
  Speaker 1: So weirdly, these two black holes are about the same
• 28:37
  Speaker 1: size in the sky, like our black hole is smaller
• 28:41
  Speaker 1: and closer when we took a picture before it's much bigger.
• 28:44
  Speaker 1: But further so, they're about the same size and the
• 28:46
  Speaker 1: sky the way like the Sun and the Moon are
• 28:49
  Speaker 1: the same size and the sky, even though one is
• 28:51
  Speaker 1: obviously much bigger than the other, right, right, And what
• 28:54
  Speaker 1: if you put a donut on the surface of the Sun,
• 28:57
  Speaker 1: then you get a toasted doughnut. So I think what
• 28:59
  Speaker 1: you're saying is that our our black hole in the
• 29:01
  Speaker 1: middle of our galaxy is basically like a baby black hole. Right,
• 29:04
  Speaker 1: it's like a thousand times smaller than some of the
• 29:07
  Speaker 1: big boys that you see out there, exactly. And so
• 29:09
  Speaker 1: to put it in like more familiar units, the width
• 29:12
  Speaker 1: of this black hole, the radius of it was predicted
• 29:14
  Speaker 1: to be about point one a u, like ten percent
• 29:17
  Speaker 1: of the distance between the Earth and the Sun. So
• 29:20
  Speaker 1: if you like put it in our solar system, it
• 29:23
  Speaker 1: would fit within Mercury's orbit. Right, it's not that big
• 29:26
  Speaker 1: compared to like other astronomical objects. There are stars out
• 29:29
  Speaker 1: there that are much bigger than this black hole. Oh wow,
• 29:33
  Speaker 1: So it would fit within our solar system, but it
• 29:34
  Speaker 1: would probably make our solar system collapse, right, because it
• 29:38
  Speaker 1: is four million times the mass of our sun exactly.
• 29:40
  Speaker 1: I'm not suggesting anybody try this. I'm just trying to
• 29:42
  Speaker 1: give you a sense of scale. So we knew how
• 29:44
  Speaker 1: massive it was, and that tells us how big it
• 29:46
  Speaker 1: should be. The problem is, how do you actually measure
• 29:49
  Speaker 1: its radius? How do you tell how big this thing is?
• 29:52
  Speaker 1: All we had previously were stars that are whizzing around it,
• 29:55
  Speaker 1: but they weren't coming that close to the black hole.
• 29:57
  Speaker 1: They only came to within like twelve or fish teen
• 30:00
  Speaker 1: au of this black hole, So we knew there was
• 30:03
  Speaker 1: a big, massive thing there. We knew that its radius
• 30:06
  Speaker 1: had to be less than about twelve a U, but
• 30:08
  Speaker 1: that didn't mean that it was a black hole with
• 30:10
  Speaker 1: the radius point one au. So we need to do
• 30:13
  Speaker 1: it was like verify that it really was that compact,
• 30:16
  Speaker 1: that it wasn't like a larger, fluffier object. I see,
• 30:20
  Speaker 1: because I guess there's sort of a one to one
• 30:22
  Speaker 1: relationship between the mass of a black hole and its size, right,
• 30:26
  Speaker 1: Like black holes don't vary in density. I guess, like
• 30:29
  Speaker 1: you can't have a fluffy black hole and a really
• 30:31
  Speaker 1: compact black hole. It's like a black hole is a
• 30:33
  Speaker 1: black hole mostly like if we're talking about black holes
• 30:35
  Speaker 1: that don't spin, then a certain mass black hole tells
• 30:38
  Speaker 1: you exactly the radius. You can look it up. It's
• 30:40
  Speaker 1: called the short styles radius. It's a very simple calculation.
• 30:43
  Speaker 1: If black holes are spinning, it's a little bit different
• 30:46
  Speaker 1: because then their radius depends a little bit on their spin,
• 30:49
  Speaker 1: but not by a factor of like a hundred or ten.
• 30:51
  Speaker 1: You know, we're talking about like a factor of twenty.
• 30:54
  Speaker 1: If it's spinning, it can be a little larger or smaller.
• 30:56
  Speaker 1: So mostly a black holes radius is determined by its mass,
• 30:59
  Speaker 1: as you say it. But then how do we get
• 31:02
  Speaker 1: the prediction for our black hole? Because we did we
• 31:05
  Speaker 1: know if it was spinning or not. We didn't know
• 31:07
  Speaker 1: if it was spinning, So the prediction there is just
• 31:09
  Speaker 1: for like a short side black hole. But still we
• 31:11
  Speaker 1: only had like data that suggested that it was smaller
• 31:14
  Speaker 1: than like twelve AU, and the prediction for a non
• 31:17
  Speaker 1: spinning or a spinning black hole were all much much smaller.
• 31:20
  Speaker 1: They were like five or ten percent of an a U.
• 31:23
  Speaker 1: So we were like an order of magnitude away from
• 31:26
  Speaker 1: really knowing even that this was a black hole until
• 31:29
  Speaker 1: we got data that came much much closer to the
• 31:32
  Speaker 1: center of the black hole, right. I think we talked
• 31:33
  Speaker 1: about this in another podcast, like we physicists saw a
• 31:37
  Speaker 1: cloud of gas get near the black hole and that
• 31:40
  Speaker 1: sort of give us an estimate of how big it was. Yeah,
• 31:42
  Speaker 1: there was this gas cloud G two which people saw
• 31:45
  Speaker 1: it was like on a path to go pretty close
• 31:47
  Speaker 1: to the black hole and give us a sense for
• 31:49
  Speaker 1: like what its strength was. It was pretty weird because
• 31:52
  Speaker 1: people expected the gas cloud to be torn up by
• 31:55
  Speaker 1: the title forces in the gravity of the black hole,
• 31:58
  Speaker 1: and they thought that would really give them a clue
• 31:59
  Speaker 1: as how powerful it is and the radius of it.
• 32:01
  Speaker 1: But it sort of wasn't torn up the way they expected,
• 32:04
  Speaker 1: which made people wonder like, maybe it's actually a big
• 32:08
  Speaker 1: fluffy object and the gas clouds sort of passed through
• 32:11
  Speaker 1: this big fluffy object instead of like a dense object
• 32:14
  Speaker 1: and just at the heart of it. Other people thought, oh,
• 32:15
  Speaker 1: maybe it's not just a gas cloud. Maybe there's like
• 32:18
  Speaker 1: some stars inside of it holding it together. So that
• 32:20
  Speaker 1: was a bit of a mystery and it led people
• 32:22
  Speaker 1: to suggest instead of there being a black hole there,
• 32:24
  Speaker 1: maybe there was a big fluffy cloud of weird dark
• 32:27
  Speaker 1: matter objects called dark e nose, and we do indeed
• 32:29
  Speaker 1: have a whole podcast episode exploring that one. M I
• 32:32
  Speaker 1: see right. We need the stars around that area. We're
• 32:35
  Speaker 1: going around something heavy, But we didn't know if it
• 32:37
  Speaker 1: was a black hole or something which is really dense, right,
• 32:40
  Speaker 1: because it's it's kind of impossible to tell, or it
• 32:42
  Speaker 1: was impossible to tell exactly. And the most conclusive way
• 32:45
  Speaker 1: to know that it really is a black hole is
• 32:47
  Speaker 1: to look at the accretion disk, the stuff that's the
• 32:49
  Speaker 1: closest possible to the black hole, because that will reveal
• 32:53
  Speaker 1: the radius of the event horizon. Like you can't see
• 32:56
  Speaker 1: the event horizon, but you can see the stuff just
• 32:58
  Speaker 1: outside the event horizon, and that tells you where the
• 33:01
  Speaker 1: event horizon is. And if that confirms with your calculation
• 33:05
  Speaker 1: of where it should be, then that's pretty strong evidence
• 33:07
  Speaker 1: that it really is a black hole and not something else.
• 33:10
  Speaker 1: I see. Well, that's assuming it has an increation this, right.
• 33:13
  Speaker 1: Not all black holes haven't increation this, that's right. It's
• 33:16
  Speaker 1: assuming that it has one and that you can see it, right,
• 33:19
  Speaker 1: And so if it's a black hole that's just all
• 33:21
  Speaker 1: by itself, then you have no hope of measuring its
• 33:23
  Speaker 1: event horizon directly unless you're shooting donuts added or something.
• 33:26
  Speaker 1: But most black holes, you know, because they are actively
• 33:29
  Speaker 1: sucking stuff in, we'll have some kind of accretion disk.
• 33:31
  Speaker 1: But you're right, until we took this picture, we didn't
• 33:33
  Speaker 1: know what was there exactly around this tiny little dots
• 33:37
  Speaker 1: super duper far away. I guess if it doesn't have
• 33:40
  Speaker 1: an incretion disk, you could still see like how it
• 33:42
  Speaker 1: blocks the light that's coming from behind it. Right, If
• 33:45
  Speaker 1: you look at a picture of the sky, if you're
• 33:47
  Speaker 1: I guess you need to be closed. But if you're
• 33:49
  Speaker 1: up closed and you see that there's a spot in
• 33:51
  Speaker 1: the sky that you're not getting, you know, images of
• 33:54
  Speaker 1: pinpoint stars behind it, then that's also sort of a
• 33:57
  Speaker 1: picture of a black hole. Right. You'd have to know
• 33:59
  Speaker 1: a lot about the light field behind the black hole
• 34:02
  Speaker 1: to know what you're missing, so you're not confusing it,
• 34:05
  Speaker 1: which is like, oh, there's a gap in the stars,
• 34:07
  Speaker 1: or there's something else blocking you that's even further away. Right,
• 34:11
  Speaker 1: it looks to be that size. So that's why the
• 34:13
  Speaker 1: most direct evidence is in decreasing disc immediately around the
• 34:16
  Speaker 1: black hole. Right, And that is what the picture that
• 34:19
  Speaker 1: was released yesterday was. It was a picture basically like
• 34:23
  Speaker 1: a ring or a bright donut. That's the bright rings.
• 34:25
  Speaker 1: You're seeing the accretion disk, you're seeing light emitted from
• 34:28
  Speaker 1: the gas around the black hole, and then very excitingly,
• 34:31
  Speaker 1: you see a hole at this center of it. You
• 34:33
  Speaker 1: see something black. Like if it had been just a circle,
• 34:36
  Speaker 1: they would say, that's weird. We're seeing light from where
• 34:39
  Speaker 1: there should be a black hole. So that would have
• 34:41
  Speaker 1: been disappointing or it would have confused us. But we
• 34:44
  Speaker 1: in fact see a ring, and we see a hole
• 34:46
  Speaker 1: in the center of it, and that hole is exactly
• 34:48
  Speaker 1: the size you would expect it to be if there
• 34:50
  Speaker 1: is indeed a black hole with massive four million times
• 34:53
  Speaker 1: the mass of our sun. Yeah, so you can look
• 34:55
  Speaker 1: up pictures of this space donut. If you look up
• 34:58
  Speaker 1: I guess Milky Way, black Hole Hole and Discovery, you'll
• 35:01
  Speaker 1: probably find pictures of it. Now, Daniel, I'm not a
• 35:03
  Speaker 1: conspiracy theorist, and I totally trust that you physicists, but
• 35:06
  Speaker 1: it is a little suspicious. I think that the two
• 35:09
  Speaker 1: pictures of black holes we've gotten are like these perfect
• 35:12
  Speaker 1: little donuts, Like, what are the chances that these two
• 35:17
  Speaker 1: black holes that we look at You're looking at the
• 35:18
  Speaker 1: doughnut right, like from the top of the doughnut right,
• 35:21
  Speaker 1: because the donut could have been on its side, and
• 35:23
  Speaker 1: then we'd be like, oh, what is that. Yeah, it's
• 35:24
  Speaker 1: not a coincidence that these two things look similar. These
• 35:27
  Speaker 1: are the two best target black holes for this telescope,
• 35:31
  Speaker 1: Like the Milky Way black hole is the closest big
• 35:34
  Speaker 1: black hole to us, and m AD seven is like
• 35:36
  Speaker 1: one of the biggest nearby black holes. And coincidentally, they
• 35:40
  Speaker 1: appear to be about the same size in our sky.
• 35:43
  Speaker 1: So they're like number one and number two targets of
• 35:45
  Speaker 1: this telescope, And we didn't know until we looked at
• 35:48
  Speaker 1: them what their angles were, like, are these things aligned
• 35:52
  Speaker 1: with the galaxy? Are they out of alignment with the galaxy?
• 35:54
  Speaker 1: We didn't know until we looked at them. And it's
• 35:56
  Speaker 1: not even that easy to tell how the accretion disc
• 35:59
  Speaker 1: is allowed because there's a lot of distortion around the
• 36:01
  Speaker 1: black hole, you know, for example, like you can see
• 36:03
  Speaker 1: the part of the acretion disc that's behind the black
• 36:06
  Speaker 1: hole because light from it goes up and it gets
• 36:08
  Speaker 1: bent around the black hole. In two hour telescopes, so
• 36:11
  Speaker 1: you're almost always going to see the whole donut. No
• 36:13
  Speaker 1: matter what the orientation of the black hole is, right,
• 36:15
  Speaker 1: But if the donut is on its side, like perfectly
• 36:18
  Speaker 1: on its side from our view, it wouldn't look like
• 36:21
  Speaker 1: such a perfect donut. Of the picture that we're seeing.
• 36:24
  Speaker 1: The day that we have is really pretty fuzzy, and
• 36:26
  Speaker 1: so it's not easy to measure the angle of that donut.
• 36:29
  Speaker 1: And surprisingly a black hole that you look at sort
• 36:32
  Speaker 1: of side on, and in a black hole that you
• 36:34
  Speaker 1: look at sort of top down. Remember that a black
• 36:36
  Speaker 1: hole is a sphere, of course, so every direction is
• 36:38
  Speaker 1: the same. Black Holes are also spinning, so this accretion
• 36:42
  Speaker 1: disk around them has sort of a direction. Right, it's
• 36:45
  Speaker 1: like flat in two dimensions. It's really like, you know,
• 36:47
  Speaker 1: it's sort of the way the galaxy is flat, or
• 36:49
  Speaker 1: the way the Solar system is flat. The acretion disc
• 36:51
  Speaker 1: is like a tire around the black hole, right, or
• 36:54
  Speaker 1: like a record at a flat object around it if
• 36:57
  Speaker 1: you look at it edge on, if you look at
• 36:58
  Speaker 1: a top down, it doesn't actually look that different because
• 37:01
  Speaker 1: our picture is still pretty fuzzy, right. We can't really
• 37:04
  Speaker 1: resolve those kinds of differences. They try to do it,
• 37:07
  Speaker 1: and they think they have an idea for what the
• 37:09
  Speaker 1: angle of the black hole is, but it's not as
• 37:11
  Speaker 1: easy as you might imagine. It's not just like if
• 37:14
  Speaker 1: you look at it edge on, it looks like a line,
• 37:15
  Speaker 1: and if you look at it top down, it looks
• 37:17
  Speaker 1: like a circle because there's a lot of distortion from
• 37:20
  Speaker 1: the black hole itself. Even if you look at it
• 37:22
  Speaker 1: edge on, you still see the back of the accretion disk,
• 37:25
  Speaker 1: of the part that's blocked from you by the black hole.
• 37:28
  Speaker 1: And I see I think you're saying that the picture
• 37:30
  Speaker 1: is still not high enough resolution or it's still fuzzy
• 37:33
  Speaker 1: enough that we actually can't tell if we're looking at
• 37:35
  Speaker 1: the door from the top or the side. We can't tell.
• 37:38
  Speaker 1: But they do have an idea. The models that they're
• 37:40
  Speaker 1: using to describe this black hole are best described by
• 37:43
  Speaker 1: one where the black hole is actually sort of pointing
• 37:45
  Speaker 1: right at us, like we're looking at this thing weirdly,
• 37:48
  Speaker 1: almost top down. The data we're getting is most consistent
• 37:51
  Speaker 1: with us looking straight down on the top of the
• 37:53
  Speaker 1: black hole, like the accretion disk is sort of flat
• 37:56
  Speaker 1: with respect to us, which is a huge coincidence, like
• 38:00
  Speaker 1: you know, right, because it could have been pointing anywhere,
• 38:03
  Speaker 1: but it somehow it seems to be pointing right at
• 38:05
  Speaker 1: us in our spot in the Milky Way. It is
• 38:07
  Speaker 1: a really big coincidence. You might have expected the black
• 38:10
  Speaker 1: hole to be aligned with the galaxy right, that it's
• 38:12
  Speaker 1: spin would be arranged the same way as the galaxy
• 38:15
  Speaker 1: is spinning. But remember the black hole is a tiny
• 38:17
  Speaker 1: little part of the galaxy. It is not like a
• 38:19
  Speaker 1: very big fraction of the galaxy's mass. You wouldn't expect
• 38:22
  Speaker 1: it necessarily to be spinning the same way the galaxy does,
• 38:25
  Speaker 1: the way the Sun spins the way the Solar system does. Right,
• 38:27
  Speaker 1: the Sun is a huge fraction of the Solar systems mass.
• 38:31
  Speaker 1: It's most of the Solar System that the fact that
• 38:33
  Speaker 1: the Solar System spins with the Sun is not a surprise.
• 38:35
  Speaker 1: The black hole is a tiny dot at the heart
• 38:37
  Speaker 1: of the galaxy, so it can basically spin in any direction,
• 38:40
  Speaker 1: And you're right, it's a big coincidence that happens to
• 38:42
  Speaker 1: be spinning in a way that we look at it
• 38:44
  Speaker 1: sort of top down, and so we're very lucky actually
• 38:47
  Speaker 1: that there is no quois are there, because they would
• 38:49
  Speaker 1: be shooting right at us. It's like staring down the
• 38:53
  Speaker 1: barrel of a gun. So I guess what exactly did
• 38:56
  Speaker 1: we see in this picture of them that it confirmed
• 38:58
  Speaker 1: the size that we thought it was going to be,
• 38:59
  Speaker 1: or is the black hole they're bigger or smaller, So
• 39:02
  Speaker 1: it's exactly the size that we expected to be. Like,
• 39:04
  Speaker 1: we don't have great resolution, but we can measure the
• 39:06
  Speaker 1: event horizon looking the black hole shadow and it's too
• 39:10
  Speaker 1: within ten percent of what we expect. That it's like
• 39:12
  Speaker 1: really bang on. So it's in the series of you know,
• 39:15
  Speaker 1: big astronomical announcements that all say, yeah, no surprises. Einstein
• 39:20
  Speaker 1: was right again. That Einstein so annoying, always right. You know.
• 39:25
  Speaker 1: We love that we have this theory general relativity, that
• 39:28
  Speaker 1: it describes space and space time and black holes and
• 39:31
  Speaker 1: all sorts of stuff. We're also waiting for it to
• 39:33
  Speaker 1: break down. We're desperate to find a crack in it.
• 39:35
  Speaker 1: Not because we're rooting against Einstein, we love the guy,
• 39:38
  Speaker 1: but because we want to learn something. We only learn
• 39:41
  Speaker 1: something when the theory fails, when it disagrees with the
• 39:44
  Speaker 1: universe and gives us a clue about how to change
• 39:47
  Speaker 1: the theory. So it's satisfying that it works, but it's
• 39:50
  Speaker 1: also frustrating because it was an opportunity to learn something
• 39:53
  Speaker 1: new about the universe to get a clue about the
• 39:56
  Speaker 1: direction of quantum gravity. Come on a minute, Daniel, you're
• 39:59
  Speaker 1: rooting against its yes, yes, yes, I'm rooting against science.
• 40:03
  Speaker 1: I mean, like, look, we know Einstein was wrong. I
• 40:05
  Speaker 1: mean I get crackpot emails every day to say Einstein
• 40:08
  Speaker 1: was wrong, and I rolled my eyes. But the truth
• 40:10
  Speaker 1: is that we do know that Einstein has to be wrong. Right.
• 40:13
  Speaker 1: There's no way that general relatively is an accurate description
• 40:17
  Speaker 1: of the universe. It's inconsistent with quantum mechanics that predicts
• 40:20
  Speaker 1: absurd things like singularities, points of infinite density. We know
• 40:24
  Speaker 1: it breaks down, we just have never seen it happen. Yet. Well,
• 40:28
  Speaker 1: I don't think I stgin Mines. You know, he's not
• 40:30
  Speaker 1: really around anymore. I said, you're appointed yourself speaker for
• 40:33
  Speaker 1: the Einstein state. All right, Well, it is an amazing
• 40:37
  Speaker 1: discovery and an incredible feat of science and engineering to
• 40:40
  Speaker 1: take the picture of a tiny black hole in the
• 40:42
  Speaker 1: middle of a busy and cloudy galaxy. And so let's
• 40:46
  Speaker 1: get into how scientists were able to do this and
• 40:49
  Speaker 1: what it could all means for understanding of galaxies. And
• 40:52
  Speaker 1: there are origins. But first let's take another quick break.
• 41:08
  Speaker 1: All right, we're talking about how to take pictures of donuts,
• 41:11
  Speaker 1: right because I guess because its are really just instagrammers,
• 41:14
  Speaker 1: that's right. And before you eat anything you have to
• 41:16
  Speaker 1: take a picture of it. I guess, yeah, because you're
• 41:21
  Speaker 1: gonna eat it and it's gonna turn into something gross
• 41:23
  Speaker 1: in a second. Right, better take a picture before you
• 41:27
  Speaker 1: eat it. You're saying, yeah, i'd agree with that. Yeah,
• 41:30
  Speaker 1: not after you digested. Definitely. Nobody wants to see those pictures.
• 41:34
  Speaker 1: Here's my mouth full of chewed up donut. That's a
• 41:37
  Speaker 1: that's a black hole. You don't want to take a
• 41:39
  Speaker 1: picture of it, for sure. That's the way to lose
• 41:42
  Speaker 1: followers on social media or game strange ones. No matter
• 41:46
  Speaker 1: what your weirdness is, somebody out there into it. Yeah.
• 41:49
  Speaker 1: So we took a picture of the black hole in
• 41:50
  Speaker 1: the middle of our galaxy. It was big news and
• 41:52
  Speaker 1: it was a huge endeavor. I mean, you need a
• 41:55
  Speaker 1: telescope basically as big as you can make it here
• 41:57
  Speaker 1: on Earth. It's like the size of the Earth exactly.
• 42:00
  Speaker 1: They use this event Horizon telescope, which is actually a
• 42:03
  Speaker 1: network of telescopes around the Earth, so it's not like
• 42:06
  Speaker 1: one big telescope the size of the Earth. But if
• 42:09
  Speaker 1: you use a bunch of telescope simultaneously, you can get
• 42:12
  Speaker 1: almost the same power as if you had a telescope.
• 42:15
  Speaker 1: The size of the distance between your telescopes called interferometry.
• 42:20
  Speaker 1: It's really cool technique, yeah, because I think what maybe
• 42:22
  Speaker 1: something that people don't realize is that you know that
• 42:25
  Speaker 1: these telecopes don't sort of work the same way as
• 42:28
  Speaker 1: an optical telescope works. I mean, sort in principle it
• 42:31
  Speaker 1: is the same thing, but they actually use a lot
• 42:33
  Speaker 1: of sort of math and a lot of kind of
• 42:36
  Speaker 1: frequency analysis to sort of resolve the picture. Right, So
• 42:39
  Speaker 1: these things are not optical telescopes. You're right, there are
• 42:41
  Speaker 1: radio telescopes. So if you actually go to look at one,
• 42:44
  Speaker 1: they're just a bunch of antenna, right. There's not like
• 42:46
  Speaker 1: lenses and curved dishes that kind of stuff. There's just
• 42:49
  Speaker 1: a bunch of antennas. Right. They're collecting radio waves from
• 42:52
  Speaker 1: the center of the galaxy. And the way you put
• 42:54
  Speaker 1: them together to make a really big telescope is that
• 42:57
  Speaker 1: you point them all towards the same location, you nchronize
• 43:00
  Speaker 1: them all with really really precise like atomic clocks, and
• 43:03
  Speaker 1: then when a message arrives from somewhere really really far away,
• 43:06
  Speaker 1: like washes over the surface of the Earth, and you
• 43:09
  Speaker 1: sample it at different places around the Earth and then,
• 43:12
  Speaker 1: as you say, do a bunch of math to reconstruct
• 43:14
  Speaker 1: what must have been sending you this picture, right, because
• 43:16
  Speaker 1: you're sort of looking at for the nuances in the
• 43:19
  Speaker 1: signals between like the telescope in Australia and the one
• 43:22
  Speaker 1: in America, and so those subtle differences you have to
• 43:25
  Speaker 1: like use some incredible kind of maths and frequency analysis
• 43:29
  Speaker 1: to resolve those differences. And then somehow those differences give
• 43:32
  Speaker 1: you the picture of the black hole. Yeah, Like how
• 43:34
  Speaker 1: you say, somehow like it's magic or something. Yeah, YadA, YadA, YadA.
• 43:38
  Speaker 1: Twenty years of a PhD students of a three hundred
• 43:41
  Speaker 1: PC students life and you get a picture. But it's
• 43:43
  Speaker 1: something that we can actually understand a little bit. It
• 43:45
  Speaker 1: just comes down to interference. Like if you're getting life
• 43:48
  Speaker 1: from two different spots in the sky, one to the
• 43:50
  Speaker 1: left and one to the right, and when they get
• 43:52
  Speaker 1: to your antenna, they're either going to interfere in a
• 43:54
  Speaker 1: way that adds up to each other, like they make
• 43:56
  Speaker 1: each other stronger, or they're going to interfere in a
• 43:58
  Speaker 1: way that destructs each ech other, that suppresses each other,
• 44:01
  Speaker 1: like they cancel out, because these in the end are
• 44:03
  Speaker 1: just waves, So either they push in the same direction
• 44:05
  Speaker 1: to enhance each other, or they push in opposite directions
• 44:08
  Speaker 1: to cancel out. Now, if I'm on one spot of
• 44:11
  Speaker 1: the Earth and I'm looking at these two points in
• 44:12
  Speaker 1: the sky, I'll see a different kind of interference then
• 44:15
  Speaker 1: you will if you're on the other side of the Earth,
• 44:17
  Speaker 1: because the interference depends on how long it took the
• 44:20
  Speaker 1: waves to get to you. So if you have like
• 44:22
  Speaker 1: a different relative distance to those two points in the
• 44:24
  Speaker 1: sky that I do, you'll see a different interference pattern.
• 44:27
  Speaker 1: And if we compare what we are seeing, that will
• 44:29
  Speaker 1: give us a clue about how far apart these two
• 44:32
  Speaker 1: things are and what their relative brightness is. Remember that
• 44:35
  Speaker 1: you only get interference if you are seeing light from
• 44:38
  Speaker 1: more than just a point source. You need some sort
• 44:40
  Speaker 1: of extended source so that you can see different interference
• 44:44
  Speaker 1: when you're on different sides of the Earth, different parts
• 44:47
  Speaker 1: of this extended telescope. And if you just looked at
• 44:49
  Speaker 1: a point, for example, then you wouldn't get interference because
• 44:52
  Speaker 1: all the light would have the same number of wavelengths
• 44:55
  Speaker 1: traversed on its way to you. That's why interferometry lets
• 44:59
  Speaker 1: you understand the ape of a distant object. If it's extended,
• 45:02
  Speaker 1: you can resolve a picture of it by looking at
• 45:05
  Speaker 1: it from different locations to get different interference. But if
• 45:08
  Speaker 1: it has a shape, it has a size that we're
• 45:10
  Speaker 1: gonna see different things from the left side of it
• 45:12
  Speaker 1: and the right side of it. That's going to give
• 45:14
  Speaker 1: us different interference patterns on the surface. Then as you say,
• 45:17
  Speaker 1: we can do a bunch of map to figure out
• 45:19
  Speaker 1: what that means. And so that's why you want telescopes
• 45:22
  Speaker 1: that are really far apart, because they get like a
• 45:24
  Speaker 1: different interference pattern if they're far apart, and that's the
• 45:27
  Speaker 1: key to reconstructing the shape of this thing that you're
• 45:30
  Speaker 1: looking at. Right, And I guess we used the whole
• 45:33
  Speaker 1: earth to keep them as far apart as possible. Right,
• 45:36
  Speaker 1: Like how many telescopes or how many antennas were involved
• 45:38
  Speaker 1: at this event? Horizon telescope. They're all over the Earth.
• 45:41
  Speaker 1: There's three hundred scientists from thirteen institutions, and there's telescopes
• 45:46
  Speaker 1: like in North America and in South America. There's one
• 45:49
  Speaker 1: in the Mediterranean, there's one even in the South Pole.
• 45:52
  Speaker 1: So if you go online you can see what this
• 45:54
  Speaker 1: network of telescopes look like. And from my camps, at
• 45:56
  Speaker 1: least six different spots on the Earth that they're collecting
• 45:59
  Speaker 1: data from. It's pretty cool. It's pretty cool that you know,
• 46:01
  Speaker 1: scientists can work, you know, across countries and cultures like that.
• 46:05
  Speaker 1: Do they synchronize using it like a zoom call, because
• 46:07
  Speaker 1: that that might be a nightmare, I know, and they
• 46:10
  Speaker 1: were like muted the first time. Probably they all got
• 46:12
  Speaker 1: messed up. I mean. The amazing thing is that they
• 46:15
  Speaker 1: recorded all of this data five years ago in April
• 46:19
  Speaker 1: of two thousand seventeen, over just five nights of observing
• 46:22
  Speaker 1: and they've been crunching the data ever since. Wait what Yeah, so,
• 46:26
  Speaker 1: like that's how long it takes to analyze the data
• 46:29
  Speaker 1: and make the picture. That's incredible, just five nights, five
• 46:33
  Speaker 1: years ago, and that's the Event Horizon telescope. Like, wouldn't
• 46:36
  Speaker 1: they just keep recording this whole time? Or is it
• 46:38
  Speaker 1: that hard to kind of even get five nights coordinated? Yeah,
• 46:42
  Speaker 1: and it's hard to get any time on these telescopes,
• 46:44
  Speaker 1: not to mention coordinating time across all of these telescopes,
• 46:48
  Speaker 1: which are run by totally different agencies in different countries.
• 46:51
  Speaker 1: It's amazing they were able to do it at all
• 46:53
  Speaker 1: because remember that you need these telescopes to be pointing
• 46:56
  Speaker 1: at this thing at the same time. The inferometry only
• 47:00
  Speaker 1: works if you have data from the same moments, so
• 47:03
  Speaker 1: you're taking the picture of the object at the same time.
• 47:06
  Speaker 1: Whoa Like, even over five nights, it was moving. It
• 47:09
  Speaker 1: was changing. Yeah, because remember that this black hole is dynamic.
• 47:12
  Speaker 1: It's active, so a picture of it at one moment
• 47:15
  Speaker 1: won't be the same as a picture of it at
• 47:17
  Speaker 1: another moment. But that's also one of the things that
• 47:20
  Speaker 1: made this black hole harder to take a picture of
• 47:22
  Speaker 1: than the last one. Because the black hole is smaller,
• 47:26
  Speaker 1: the orbit time around it is shorter, like it only
• 47:29
  Speaker 1: takes a photon thirty seconds to orbit this smaller black hole,
• 47:32
  Speaker 1: So the whole black hole is like more active. It's
• 47:35
  Speaker 1: frothing and bubbling and burping. So it's like trying to
• 47:38
  Speaker 1: take a picture of your kids when they're running around
• 47:40
  Speaker 1: after eating too many doughnuts. You're more likely to get
• 47:43
  Speaker 1: a fuzzy picture than a crisp image that you get
• 47:45
  Speaker 1: if your kid was standing still, yeah, or your neighbor's
• 47:49
  Speaker 1: kids also, unless you also fed your neighbor's kids donuts,
• 47:53
  Speaker 1: but they're probably more well behaved. Well, that's one of
• 47:57
  Speaker 1: the things we learned about this black hole at the
• 48:00
  Speaker 1: center of our guys. He's not just kind of its size,
• 48:02
  Speaker 1: which sort of confirmed everything that we thought it was
• 48:05
  Speaker 1: going to be, but also it's the one of the
• 48:07
  Speaker 1: things during is that it is so dynamic. Right, It's
• 48:10
  Speaker 1: not like a beautiful, serene scene. It's like this crazy
• 48:13
  Speaker 1: chaoss going on around the black hole. Yeah, although that
• 48:16
  Speaker 1: was a little bit surprising as well. The black hole
• 48:19
  Speaker 1: actually isn't eating as much as you might expect compared
• 48:23
  Speaker 1: to its mass. It only eats a little bit. Like
• 48:25
  Speaker 1: if the black hole were the mass of a person,
• 48:27
  Speaker 1: like a hundred kilos, it would be only eating the
• 48:29
  Speaker 1: equivalent of one grain of rice every million years. Wait
• 48:34
  Speaker 1: what Yeah, this black hole it's like forty solar masses
• 48:38
  Speaker 1: every million years, but its mass is four million solar masses. Oh,
• 48:43
  Speaker 1: I see you're saying, like its intake is about, I
• 48:46
  Speaker 1: guess millions of times smaller than its actual mass, Like
• 48:49
  Speaker 1: it's an elf and eating a couple of grains of
• 48:51
  Speaker 1: rice every few million years. That's right, it's not really
• 48:54
  Speaker 1: gobbling that much mass compared to its size. So wait,
• 48:58
  Speaker 1: are you saying that it this black hole sort of
• 49:00
  Speaker 1: like it's done growing, kind of like it already ate
• 49:03
  Speaker 1: everything it can eat around it, and so now it's
• 49:05
  Speaker 1: out of food kind of, it's just because of where
• 49:08
  Speaker 1: it is, there doesn't happen to be a lot of
• 49:10
  Speaker 1: gas around for it to eat. In the future, it
• 49:13
  Speaker 1: microw more if something comes close. And then when the
• 49:16
  Speaker 1: Milky Way and Andromeda galaxies collide in the future, the
• 49:19
  Speaker 1: two black holes at their centers will form an even
• 49:22
  Speaker 1: bigger black hole. Interesting, and so this black hole has
• 49:25
  Speaker 1: a name. It's called Sagittarius a star, but it's not
• 49:28
  Speaker 1: a star. It's just it's literally like an asterisk. That's right.
• 49:32
  Speaker 1: They put a star in the name because it was
• 49:35
  Speaker 1: an exciting discovery. Wait what for real? Yeah? Like literally,
• 49:38
  Speaker 1: they use a star to denote excited states of atoms
• 49:41
  Speaker 1: and stuff, and so they were excited about this, so
• 49:44
  Speaker 1: they gave it a stock. Don't they know they can
• 49:45
  Speaker 1: use Miley faces or emojis now. Literally, it's basically like
• 49:50
  Speaker 1: they were trying to put a little emoji there. Yeah,
• 49:52
  Speaker 1: it's like old school text emojis for real. But why
• 49:57
  Speaker 1: were they so surprised when they named this. I'd say
• 49:59
  Speaker 1: they were more were excited than surprised. I guess, well,
• 50:02
  Speaker 1: is there a Sagittarius B. I guess, like, why is
• 50:04
  Speaker 1: it called Sagittarius A star? Well, it's called Sagittarius because
• 50:07
  Speaker 1: it was found near the constellation of Sagittarius. And then
• 50:11
  Speaker 1: back in the fifties, they were scanning the sky for
• 50:14
  Speaker 1: radio sources and found this one near that constellation. It
• 50:18
  Speaker 1: was the first big bright radio source they found in
• 50:20
  Speaker 1: that part of the sky. So they called it Sagittarius A.
• 50:24
  Speaker 1: And then when they imagine there might be a black
• 50:25
  Speaker 1: hole there, they called that Sagittarius A star. So it
• 50:29
  Speaker 1: really could have just also been Sagittarius A. O MG, exactly,
• 50:32
  Speaker 1: that's precisely what the star means. So they thought it
• 50:36
  Speaker 1: was maybe a star, or they thought it was just
• 50:39
  Speaker 1: like a radio source. But then later I guess we
• 50:41
  Speaker 1: found out it's actually the black hole. Ye. Discovery of
• 50:43
  Speaker 1: this radio source was one of the things that gave
• 50:46
  Speaker 1: us a clue that black holes might be real. They
• 50:48
  Speaker 1: saw this source in the radio but then nothing in
• 50:51
  Speaker 1: the visual so they had to try to understand what
• 50:54
  Speaker 1: kind of thing had so much energy that it could
• 50:56
  Speaker 1: be that bright in the radio but dark in the optical. Alright, well,
• 51:00
  Speaker 1: what are some of the I guess, big picture things
• 51:02
  Speaker 1: we're learning from this picture, And what does it mean
• 51:05
  Speaker 1: about our understanding of black holes in general. Well, it
• 51:07
  Speaker 1: means that we are one step closer to saying for
• 51:10
  Speaker 1: sure that there is a black hole here at the
• 51:12
  Speaker 1: heart of our galaxy. We can now rule out things like,
• 51:15
  Speaker 1: you know, there's a much larger object with the same
• 51:18
  Speaker 1: mass as we thought the black hole had. We can
• 51:21
  Speaker 1: rule that out. We know that it's something around the
• 51:23
  Speaker 1: same size as we expect a black hole to be.
• 51:25
  Speaker 1: That's a pretty clear statement. It really rules out some
• 51:28
  Speaker 1: of the other crazier ideas. We also can start to
• 51:31
  Speaker 1: study in more detail, like the complicated astrophysics of what's
• 51:35
  Speaker 1: going on around the black hole. You know, one thing
• 51:37
  Speaker 1: is like the general relativity of the black hole itself.
• 51:39
  Speaker 1: The other is understanding the crazy swirling mass that's near
• 51:43
  Speaker 1: the black hole that's generating all of this crazy radiation,
• 51:46
  Speaker 1: the X rays and the quays ares, you know, just
• 51:48
  Speaker 1: understanding how that works. The magnetic feels around there. That's
• 51:51
  Speaker 1: something else that we can now start to dig into. Oh,
• 51:53
  Speaker 1: I see, because now we have a picture, we can
• 51:55
  Speaker 1: actually sort of measure and see how it's changing. I
• 51:58
  Speaker 1: guess right, because and and once you know how it's changing,
• 52:01
  Speaker 1: you understand the physics behind it a little bit more
• 52:04
  Speaker 1: because before it was all sort of theoretical and based
• 52:06
  Speaker 1: on simulations. But now we have like actual data of
• 52:08
  Speaker 1: what's going on around potential black hole. Yeah, there are
• 52:12
  Speaker 1: these two competing models for what's going on in the
• 52:14
  Speaker 1: ecretion disc, how it forms, how particles swirl around it,
• 52:18
  Speaker 1: how sometimes they fall in and sometimes they get ejected
• 52:20
  Speaker 1: up along the axis of the black hole. These two
• 52:22
  Speaker 1: models are called M A D MAD and s A
• 52:25
  Speaker 1: n E sane. So there's two competing parts of the
• 52:28
  Speaker 1: astrophysics community, the mad people and the sane people. Wait,
• 52:32
  Speaker 1: what those are? The acronyms M A D MAD and
• 52:35
  Speaker 1: saying are the competing theories about black holes? That's right,
• 52:38
  Speaker 1: you're either mad or you're saying in astrophysics, Wow, did
• 52:44
  Speaker 1: they do that on purpose? Or I don't even know
• 52:48
  Speaker 1: the whole history of that, but you know, astrophysics naming
• 52:50
  Speaker 1: an acronym or that's a whole podcast episode. Yeah, it
• 52:53
  Speaker 1: probably divides the psychology of physicists to like some of
• 52:57
  Speaker 1: them want to be known as Matt scientists, and some
• 52:59
  Speaker 1: of them want to be like, no, let's be saying
• 53:01
  Speaker 1: exactly so now they can dig deeper into their models
• 53:04
  Speaker 1: and understand what's going on. What's fascinating is that none
• 53:07
  Speaker 1: of the models that we have currently perfectly describe what
• 53:11
  Speaker 1: we see, Like some of them are pretty good but
• 53:13
  Speaker 1: fail in this aspect, and some of them are pretty
• 53:15
  Speaker 1: good in other aspects but fail one part of it.
• 53:17
  Speaker 1: So none of our astrophysics models for the creation disc
• 53:20
  Speaker 1: perfectly describe what we see, which gives us fuel to
• 53:22
  Speaker 1: learn more about what's happening in the vicinity of these
• 53:25
  Speaker 1: black holes. Pretty cool, and it's also significant because it's
• 53:28
  Speaker 1: our black hole, right, Like, it's the one closest to us,
• 53:31
  Speaker 1: it's the one that's basically at the center of our galaxy.
• 53:34
  Speaker 1: It's we have some sort of ownership over I guess, right,
• 53:37
  Speaker 1: or at least relationship. Yeah, it's our little cozy neighborhood
• 53:40
  Speaker 1: black hole. And as you say, it's changing. And what
• 53:43
  Speaker 1: they're planning to do next is to turn on the
• 53:46
  Speaker 1: event horizon telescope for longer and try to crunch the
• 53:49
  Speaker 1: data more powerfully so they can make a movie of
• 53:52
  Speaker 1: this black hole. So not just a picture, but like
• 53:55
  Speaker 1: a movie where you can see it changing and bubbling
• 53:57
  Speaker 1: and frothing. Interesting. So five days of data is not
• 54:01
  Speaker 1: enough to make a movie. Five days of data is
• 54:03
  Speaker 1: just enough to make a picture, And which you really
• 54:05
  Speaker 1: need are more telescopes even so you can get more
• 54:08
  Speaker 1: data for the same moments, so you can resolve it
• 54:11
  Speaker 1: and make it sharper without having to integrate over that
• 54:13
  Speaker 1: as much time. When they took this picture, they're basically
• 54:16
  Speaker 1: assuming that it's not changing, and that adds to some
• 54:18
  Speaker 1: of the fuzz of the picture. But if instead you
• 54:21
  Speaker 1: can get the same sharpness by adding more telescopes, then
• 54:23
  Speaker 1: you can use shorter time windows to take each picture,
• 54:27
  Speaker 1: and then you can get a movie. Oh that's pretty exciting,
• 54:30
  Speaker 1: because you know everything's willing to a video, right, it's
• 54:33
  Speaker 1: going to go from Instagram to TikTok now. Although the
• 54:35
  Speaker 1: data that they've collected is like eight head of bites
• 54:38
  Speaker 1: a data per day as they were collecting it, which
• 54:40
  Speaker 1: is the equivalent of a hundred million TikTok videos. So yeah,
• 54:45
  Speaker 1: turning all these videos out, which is how many TikTok
• 54:48
  Speaker 1: videos get made an hour, right, right, so no problem,
• 54:52
  Speaker 1: and most of them have dogs and cats and horses
• 54:54
  Speaker 1: in them anyway, All right, Well, pretty exciting news and
• 54:57
  Speaker 1: pretty amazing I guess milestone or humanity to take a
• 55:01
  Speaker 1: picture of the black hole at the center of our
• 55:03
  Speaker 1: galaxy and to like see it and confirm that it's there,
• 55:06
  Speaker 1: and to confirm all these incredible theories that had so
• 55:10
  Speaker 1: far just been in people's heads. Kind of right, Yeah,
• 55:13
  Speaker 1: it's really exciting to see these things in reality. You know,
• 55:16
  Speaker 1: you have ideas for how the universe is working, for
• 55:19
  Speaker 1: what should be going on, but until you go out
• 55:21
  Speaker 1: there and look, you don't know. And sometimes the universe
• 55:24
  Speaker 1: comes back and tells you, oh, yeah, that's exactly what
• 55:26
  Speaker 1: you thought it was. And sometimes the universe comes back
• 55:29
  Speaker 1: and says, oh, you silly human it's secret options. See,
• 55:32
  Speaker 1: so this time it told us, yeah, it's a black
• 55:35
  Speaker 1: hole and it's just the way you thought. And that's
• 55:36
  Speaker 1: also exciting. Yeah, it's exciting, even if it means Einceland
• 55:40
  Speaker 1: was right, Sorry, Daniel, exactly, Einstein was right again. Go
• 55:45
  Speaker 1: get your free donut. You'll feel bad. That's right, but
• 55:47
  Speaker 1: I'm still here to eat donuts and he's not che Einstein. Yeah,
• 55:53
  Speaker 1: for how long. We'll see. If you keep eating too
• 55:56
  Speaker 1: many donuts, you he'll beat you in lifespan, probably exactly.
• 56:00
  Speaker 1: My theory of lifespan is is give a limited number
• 56:02
  Speaker 1: of donuts. When you eat in them all, you're done. Well, um,
• 56:06
  Speaker 1: you'll have to go into a black hole to get more,
• 56:09
  Speaker 1: or I'll have to eat a black hole flavor donut.
• 56:12
  Speaker 1: All right, Well, we hope you enjoyed that, and we
• 56:14
  Speaker 1: hope that you go out there and learn more about
• 56:16
  Speaker 1: this incredible discovery. Thanks for joining us, See you next time.
• 56:27
  Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
• 56:30
  Speaker 1: the Universe is a production of I Heart Radio. For
• 56:33
  Speaker 1: more podcast For my Heart Radio, visit the I heart
• 56:36
  Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your
• 56:40
  Speaker 1: favorite shows. Ye