Cosmic Queries – Black Hole Paradox with Matt O’Dowd

Can we use gravitational lensing to view distant planets? Neil deGrasse Tyson and comedian Chuck Nice explore black holes, quasars, entropy, and more with astrophysicist and host of PBS Space Time, Matt O’Dowd.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  On the next episode of StarTalk, it's a cosmic queries with my friend and colleague, Matt O'Dowd, who's an expert in weird and wacky stuff in the universe, including black holes, quasars, gravitational lenses, and the like. So what is at the threshold of a quasar? Could the big rip rip into black holes? And more, coming up on StarTalk Cosmic Queries.

• 0:32Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:45Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. A guy with me, Chuck. Nice, Chuck, baby. Hey, hey, hey, Neil, what's happening? All right, we're doing cosmic queries today. Yes. Yeah, and today we've got a friend and colleague, a friend of StarTalk and a friend of mine, Matt Dowd. Matt, welcome back to StarTalk. Great to be here again, Neil. How you doing? And Matt, is that a fake Zoom background behind you? Or like, what is that? Well, if the simulation hypothesis is correct, then yes. But I think I'm actually outside. I'm on my deck.

• 1:23Neil deGrasse Tyson?

  Very nice. No, I think we hear birds and things. That's very beautiful. Your expertise is black holes, quasars, gravitational lensing, really juicy, tasty cosmic things, all of which will kill you if you come in the vicinity of them. Immediately. The most hostile part of the cosmos. Exactly. You teach at Lehman College of the City University of New York. You're also an associate here at the Department of Astrophysics at the American Museum of Natural History, and you're a host and writer for the YouTube channel for PBS Spacetime, which has nearly 3 million subscribers. Dude, you're rocking it.

• 2:05Neil deGrasse Tyson?

  Okay.

• 2:06Chuck Nice?

  Killing it.

• 2:07Neil deGrasse Tyson?

  Totally killing it. So Matt, I see you're like into a film called Inventing Reality. What's, what's going on there?

• 2:14Matt O'Dowd?

  Yeah, this is a film that we recently got crowdfunded and we're in the process of writing.

• 2:19Neil deGrasse Tyson?

  Oh, love that. Love that. Okay. Uh huh. And what's it about?

• 2:22Matt O'Dowd?

  It is about our quest for the fundamental. It's about humanity's search for the underlying clockwork of nature, both from the point of view of physics, but also from the point of view of neuroscience, brain science. So it's connecting how our brains construct our models of the world and, and how that fact is connected to how science at a societal level constructs its models of the world.

• 2:50Neil deGrasse Tyson?

  And, and you have a collaborator? Who's your collaborator?

• 2:53Matt O'Dowd?

  So, uh, working with my partner, Bahar Golepur, who's a neuroscientist. Uh, we're writing it together. Um, and it's being produced, uh, with and directed by Andrew Corden-Haber, who's part of the space-time team.

• 3:09Neil deGrasse Tyson?

  Okay.

• 3:09Chuck Nice?

  Very nice, very nice.

• 3:10Neil deGrasse Tyson?

  So everyone should have like a neuroscientist at arm's reach.

• 3:13Matt O'Dowd?

  Hundred percent.

• 3:14Chuck Nice?

  Without a doubt.

• 3:15Neil deGrasse Tyson?

  I'm not alone. I'm not alone in that.

• 3:18Chuck Nice?

  Except I have to pay mine by the forty-five minute.

• 3:22Chuck Nice?

  I, I, but I do have one at arm's reach.

• 3:24Neil deGrasse Tyson?

  Uh huh. So Chuck, we've got questions.

• 3:27Chuck Nice?

  We do.

• 3:28Neil deGrasse Tyson?

  Solicited from our Patreon members.

• 3:29Chuck Nice?

  Correct.

• 3:30Neil deGrasse Tyson?

  The threshold of access to this feature is five dollars a month.

• 3:34Chuck Nice?

  That's it.

• 3:35Neil deGrasse Tyson?

  So that's all it is. All right. So Matt, are you ready for us? Let's do it. Let's do it. All right. All right. By the way, Matt and I have overlapping, uh, expertise in the Venn diagram. So what will happen is that whatever is right in his belly work, he'll take it. But if it's something, if there's some spillage, I, I, I'll, I'll jump in too. You okay with that, Matt? Let's do it together. Okay. All right.

• 3:56Chuck Nice?

  There you go.

• 3:57Neil deGrasse Tyson?

  And, and, and, and if the spill is from that, then Chuck can pick up the slack.

• 4:00Chuck Nice?

  Right. At, at that point, we're not looking at spillers. We're looking more like at a environmental disaster. You know what I mean? That's kind of Exavon Valdez territory. It's just like, and Chuck, what do you think about black holes? We have reached a new low. Okay, here we go. Uh, this is BSM nineteen eighty-nine says, greetings, Dr. Tyson, Chuck and Dr. Matt.

• 4:27Chuck Nice?

  Well, my name is Blake and I'm from Mobile, Alabama. Can you elaborate on energy density surrounding a black hole? And how Hawking radiation might work? Uh, is the material that falls into a black hole lost forever? And, uh, does it eventually somehow get out?

• 4:49Neil deGrasse Tyson?

  Love it. That's, that's, that's all you, Matt. Take it.

• 4:52Matt O'Dowd?

  Wow. All right. So this is, to answer this question, I need to summarize a large fraction of 20th century physics in, in a minute.

• 5:02Neil deGrasse Tyson?

  Wait, wait, but we only have.

• 5:03Matt O'Dowd?

  I know. I'm gonna try.

• 5:07Neil deGrasse Tyson?

  You're gonna start your answer by saying, first let me summarize 20th century physics.

• 5:11Matt O'Dowd?

  No, no, I'm serious.

• 5:12Chuck Nice?

  So here we go, guys. The answer to your question is, I was born the son of a poor sharecropper.

• 5:20Matt O'Dowd?

  I mean, there's so much, so much of the story of the development of 20th century physics is around black holes and this exact weird thing about black holes that what goes in seems to not come out. And this, this is a paradox. Okay. So, all right. I mean, let me, let me get these questions one piece at a time. So, uh, the energy density around the black hole, I mean, uh, so first of all, let's talk about a black hole. It is a, uh, place where gravity has had its ultimate victory. So it's usually the collapsed core of a star. So you have this hyper dense region where it is, the gravity is so strong that light can't escape. Okay. We don't know what's really inside a black hole, but there's

• 6:01Matt O'Dowd?

  this region around, you know, whatever that collapsed object is where you have, uh, what we call the event horizon. And that's the distance from which light can't escape. And it's black. Okay. You, uh, and so these things are invisible. Um, you know, unless they're eating a star or a galaxy or something. And then, and then we see the mess they make. Um, but. Back in the 1960s, Stephen Hawking realised that black holes shouldn't actually be completely black, they should radiate. And this was Hawking's most famous discovery, called Hawking Radiation. And it's described in a couple of different ways. One way is that you have

• 6:41Matt O'Dowd?

  matter and antimatter particles spontaneously appearing near the event horizon. Normally, they would vanish again, destroying each other, but if one gets sucked into the event horizon, the other can escape. Okay, that's sort of the pop size level. Hawking's own description of it was talking about the positive and negative frequency modes of the quantum vacuum and how they get perturbed by the by the black hole, leaving the this, you know, the the vacuum itself generates particles which you see. Okay, so Hawking Radiation causes black holes to leak away their mass. So there's the answer to the other part of the question. When something falls into a black hole, we think now, so

• 7:24Matt O'Dowd?

  originally, we thought that that nothing could escape a black hole because nothing can travel faster than light, right? But now, I think most physicists believe that because you have this Hawking Radiation, what the at least the energy that falls into a black hole can eventually leak away as that radiation. And the the really important thing about that is that not only can the energy get out, but the information can get out. And this was what this was the other perplexing thing about black holes. It shouldn't be possible to destroy what we call quantum information. But via Hawking Radiation, many physicists now think that the the details of what you threw into the black hole somehow

• 8:08Matt O'Dowd?

  get out by this Hawking Radiation also. So they get remembered, they get remembered.

• 8:13Chuck Nice?

  Right, yeah. So it's almost like, whatever it is, although it's not a chair that went in, all of the things, the blueprint information on a on that tiny, tiny level, when it comes out, that is still available.

• 8:29Matt O'Dowd?

  Yeah, if you could, if you could go to the, you know, if you could collect all the Hawking Radiation that evaporated out of a black hole over trillions of years.

• 8:39Matt O'Dowd?

  Every little bit and somehow piece it together, the worst jigsaw puzzle in the universe, you should be able to reconstruct the chair.

• 8:46Chuck Nice?

  And that's what you guys say mean when you say information. You're talking about all the stuff that we actually are on that.

• 8:55Neil deGrasse Tyson?

  The inventory, the particle inventory.

• 8:57Chuck Nice?

  Inventory on the quantum, all the way down to the particles.

• 9:00Matt O'Dowd?

  Yeah, the information that you would need if you wanted to rewind the universe and find out what happened previously. If you had all the information, then in principle, you could, you know, run the clock backwards and figure out what fell into the black hole in the first place.

• 9:15Neil deGrasse Tyson?

  And just to clarify a point you're making, you're saying it came out of the black hole, but in fact, it came out of the energy field in the vicinity of the black hole, which counts as coming out of the black hole. Is that right?

• 9:27Matt O'Dowd?

  So this is, thank you for getting to the biggest hole in my, in my argument here. Hawking's arguments were based on sort of internal consistency arguments in that it had to exist for the universe to make sense, but the actual mechanism of its creation isn't clear. We just know it has to sort of emerge from the vicinity of the black hole somehow.

• 9:50Neil deGrasse Tyson?

  But that counts for having come out of the black hole because it's using the gravitational energy density created by the black hole and it just happens to be outside of the event horizon.

• 10:00Matt O'Dowd?

  Yeah, so one, one description of how this happens is that the thing that falls into the, into the black hole, which is, you know, your, your antiparticle or your, your negative frequency mode or whatever, somehow gains negative mass or negative energy inside the black hole. Because the, the dimensions inside the black hole get all twisted around and so it's possible to have this relative negative mass go inside, which causes the, the positive mass of the black hole to shrink a little bit.

• 10:27Chuck Nice?

  Wow. Okay.

• 10:30Neil deGrasse Tyson?

  No Chuck, isn't that obvious? That's completely obvious.

• 10:33Chuck Nice?

  My god, that is, that is insane. I love it. Wow.

• 10:38Neil deGrasse Tyson?

  All right. All right, keep going.

• 10:40Chuck Nice?

  Here we go. Hello, Dr. Tyson, Dr. O'Dell.

• 10:45Chuck Nice?

  How do we know black holes follow the second law of thermodynamics? Can black holes be regions of fixed entropy?

• 10:55Neil deGrasse Tyson?

  Oh, I like that. Because Matt, you know, we say the second law of thermodynamics. In a way, that's an observed phenomenon, right? There's no deep principle deeper than it. We just say, oh, looks like entropy increases everywhere. So let's make it a law. And maybe the black hole violates this.

• 11:17Matt O'Dowd?

  This is such a good follow on question. So the crazy thing about entropy is that it feels like it's something that just emerges from the way particles interact with each other, et cetera. But it also seems like one of the most fundamental things in physics because no matter where you look, entropy seems to increase.

• 11:39Matt O'Dowd?

  With a black hole, there is a way to think about its entropy. So we think of entropy as a measurement of the amount of disorder in a system. Okay, so a system will always move towards states of more disorder. Okay, think about, for example, the air in the room. If you took all of the air and compacted it down into, you know, a ball this size, it would, well, first of all, you'd die of asphyxiation immediately, but the air would immediately burst out to fill the room. Okay, this configuration where all the air particles are in this one spot, it would be considered a very special or very ordered configuration. And so it would be considered low entropy.

• 12:20Matt O'Dowd?

  So the only thing it can do from there is expand into a more disordered arrangement. Fill the room, there would be high entropy. On, in the case of a black hole, we can think of their entropy as, in terms of information, just like we talked about. So in the case of the air in the room, when the air fills the room. We know a lot less about the location of the particles of the of the air molecules. Okay, so we have very little information. There's a lot more hidden information in the air in the room when it's filling the whole room compared to if we have this ball of air in our hands, then we have a much better idea of at least the location of all of the particles.

• 13:05Matt O'Dowd?

  They're all in this ball of air. Okay, so entropy can can be considered as a measurement of the amount of hidden information in a system. And over time, we tend to lose more and more of the information of a system. So for a black hole, as a black hole grows, it's swallowing things from the external universe. And because we can't get information about what fell into a black hole out very easily, as a black hole grows, its entropy increases. Okay, so the amount of hidden information increases. And so there's this very tight relationship between actually the surface area of a black

• 13:49Matt O'Dowd?

  hole and the amount of stuff that it's eaten, which corresponds to the amount of information that that black hole is hiding. And so I won't get into the next point, but I got to mention, it was this simple observation that the entropy of a black hole is proportional to its surface area that led us directly to the holographic principle, the notion that the information of the interior of a volume can be completely encoded on the surface of that volume. And it led people like Leonard Susskind and others to realize that you could actually encode the interior of a universe on its surface area.

• 14:31Matt O'Dowd?

  And that's another story that that led directly from this notion of a black hole entropy.

• 14:37Neil deGrasse Tyson?

  Hmm. Okay, so we're all two dimensional holograms. That's the takeaway. That's the takeaway from this.

• 14:42Chuck Nice?

  That's it.

• 14:44Chuck Nice?

  There's a real answer.

• 14:45Neil deGrasse Tyson?

  Chuck, I always knew you were just a two dimensional person, you know.

• 14:48Chuck Nice?

  No, what you, I thought you meant my character was.

• 14:53Neil deGrasse Tyson?

  Okay.

• 14:54Chuck Nice?

  Not my physicality.

• 14:56Neil deGrasse Tyson?

  All right, all right. All right, give me another one, Chuck.

• 15:00Chuck Nice?

  That was cool. So, by the way, I don't know if I said that that was Deep and Das. That was the person that gave us that. Deep and Das.

• 15:07Neil deGrasse Tyson?

  Oh, Deep and Das. Okay.

• 15:09Chuck Nice?

  Deep and Das. Okay. Okay. And this is anthropoc cosmic Dylan.

• 15:17Neil deGrasse Tyson?

  Anthropoc cosmic.

• 15:18Chuck Nice?

  Anthropoc cosmic.

• 15:20Neil deGrasse Tyson?

  I like it. Mm hmm.

• 15:21Chuck Nice?

  Yeah, very cool. Hello, Dr. Tyson, Dr. Dow, Dr. Comedy. In space documentaries like PBS Spacetime, they talk about future cosmic events in distant galaxies on Earth timelines. Instead of saying the sun will blow up in five billion years from the perspective of a galaxy far away, how do you adjust for the time dilation so that the information you're talking about is correct in the instant? In terms of relatively, it seems like galactic simulations sort of stepped through a wormhole to film ex-solar systems.

• 15:59Neil deGrasse Tyson?

  Hmm.

• 16:00Chuck Nice?

  Or that should be exosolar, because you know.

• 16:02Neil deGrasse Tyson?

  So in other words, what, what, what is the rate at which time ticks on things we're observing? And if it's not ticking at the same rate that it was ticking here on Earth, who are we to put it on our timeline?

• 16:13Chuck Nice?

  On the Earth timeline. Which, by the way, thank you, Neil, for making me understand what the hell he was talking about.

• 16:21Neil deGrasse Tyson?

  So, why don't we pick that up when we return in segment two on StarTalk Cosmic Queries. Weird, wacky stuff that our guest, Matt O'Dowd, is an expert in when StarTalk returns.

• 16:42Speaker 03

  Hi, I'm Chris Cohen from Hallworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson.

• 17:00Neil deGrasse Tyson?

  We're back. StarTalk, Cosmic Queries. Got Chuck with me. Chuck, you still there?

• 17:05Chuck Nice?

  Yeah, I'm still there, man.

• 17:07Neil deGrasse Tyson?

  There's some deep stuff coming down here. Matt O'Dowd, friend and colleague, from Lehman College of the City University of New York. So, you're an expert. In this session, we've got you in for like quasars and black holes and weird, wacky, fun things that will kill you posthaste in the universe. So, what else you got?

• 17:29Chuck Nice?

  So, what we were talking about before the break was from Anthropoc cosmic Dylan, who is actually Dylan from San Diego. In the short, what he was talking about, it seems like galactic simulations kind of stepped through a wormhole to film extrasolar systems, exosolar systems, because, you know, they're not really on our timeline, but we put them on our timeline. So, what's the deal?

• 17:54Neil deGrasse Tyson?

  What's up with that? I mean, yeah, how do we reckon the relativistic effects, time dilation in an expanding universe on a timeline that we're just trying to set up for the universe here on Earth?

• 18:06Matt O'Dowd?

  Shall I take a shot at this deal?

• 18:09Neil deGrasse Tyson?

  Yeah, please. I just asked you. I asked you because I don't want to answer.

• 18:13Matt O'Dowd?

  All right. All right. All right. So, the stuff that I study is far enough away that this matters. Many of you have heard that the universe is expanding, which means that distant galaxies appear to be moving away from us. And you look far enough away, they're moving away from us at a big fraction of the speed of light. Okay, and so Einstein showed us that your, your, the rate at which your clock ticks depends on your motion, or the rates that you see a clock ticking depends on the motion of that clock relative to you. Okay, so fast-moving objects, you see that their clock appears to be ticking slower, right? And so I, for example, studied quasars in the very distant

• 18:58Matt O'Dowd?

  universe, and we really have to take this into account. Okay, so we might see these quasars fluctuating. Okay, these are supermassive black holes that are eating a bunch of gas from their galaxy, and they're, they're, they're pretty chaotic. They, they splutter and they splurt over time. Super interesting to study that variability. But if you're looking at something that's half a universe away, then this thing called relativistic time dilation slows down their sputtering and spurting dramatically. And so you have to remember that and put that fact into your calculation, otherwise you get it all wrong.

• 19:40Neil deGrasse Tyson?

  Oh, okay. So you do factor it in?

• 19:41Chuck Nice?

  You, you actually make the adjustment.

• 19:43Neil deGrasse Tyson?

  Yeah. Make the adjustment.

• 19:44Matt O'Dowd?

  Fortunately, fortunately, it's a, it's simple algebra. Einstein made that one easy for us.

• 19:49Neil deGrasse Tyson?

  Mm-hmm.

• 19:50Chuck Nice?

  Right, right.

• 19:50Neil deGrasse Tyson?

  Yeah, I have my one paper that is co-authored with a Nobel laureate. I'm the last author on that paper. It's, I think it was the first measurement of time dilation in a supernova light curve. Because you have supernova in the outer universe, we have predictions of how quickly they'll brighten and how slowly they will dim. And so we know what they look like nearby. And out in the universe, it was taking longer for that to happen. So we can say, is this a different kind of supernova? Or you plug in the expansion rate of the universe for its distance, and bada bing, it comes out right, right as you expected. So yeah, it wasn't actually happening slower. It was a time dilation effect. So this, this was profound. Yeah.

• 20:33Chuck Nice?

  Yeah, that's very cool. By the way, you don't have to qualify being the last author on a Nobel laureate paper. You could just be an author on the paper.

• 20:44Neil deGrasse Tyson?

  Okay.

• 20:44Chuck Nice?

  Okay?

• 20:45Neil deGrasse Tyson?

  Okay, it's enough.

• 20:47Neil deGrasse Tyson?

  The lead author was Brian Schmidt, who won the Nobel Prize for the discovery of dark energy, which was empowered by measurements such as these with supernovae. And he's in Australia now, I think.

• 21:03Matt O'Dowd?

  Yeah, he's been in Aussie for a long time. I mean, he was born in the US, I believe, but he's been, yeah.

• 21:10Neil deGrasse Tyson?

  He's down under, yeah. All right, Chuck, give me more.

• 21:15Chuck Nice?

  Moving on to Brendan Gabassi. And Brendan says, hey, this is Brendan from Lansing, Michigan. And is it possible for a black hole of any size to be a quasar, given it has enough matter around it to heat up? And how close would a quasar have to be to the Milky Way in order for us to just see it in the evening sky? And if it's not too much to ask, can you elaborate on the news that is quickly spreading about the hole that's 20 times the size of Earth in the sun? I mean, I don't think that's related to a black hole because our sun could never be one.

• 21:56Neil deGrasse Tyson?

  He's got anxiety. Be nice to the people's anxiety, Chuck.

• 21:59Chuck Nice?

  Tell me about, hey, man, stop worrying about the hole in the sun. There's a black hole sun, please.

• 22:07Neil deGrasse Tyson?

  It's a question about holes. That's all it is, right?

• 22:09Chuck Nice?

  That is a question about holes. Nice job.

• 22:12Neil deGrasse Tyson?

  Why don't you take the sun one first?

• 22:13Matt O'Dowd?

  No, the sun one, no, I, you know, I'm tempted to shift screen and Google that right now, but that would be cheating. Is it a sunspot, maybe? Galileo?

• 22:24Neil deGrasse Tyson?

  Yeah, I mean, sunspots are, you know, ordinary sunspots are about the size of the Earth, but the sun can have storms and explosions that are way bigger than Earth.

• 22:31Matt O'Dowd?

  We are approaching a solar maximum in terms of magnetic storms, so.

• 22:36Neil deGrasse Tyson?

  Right, that's in 2025.

• 22:37Matt O'Dowd?

  It's on the upswing, you know, I saw, I saw the northern lights from right here on this deck a few weeks ago for the first time in my life.

• 22:45Chuck Nice?

  Wow.

• 22:46Matt O'Dowd?

  And this is New York State, so.

• 22:48Neil deGrasse Tyson?

  Wait, wait, you saw aurora?

• 22:49Matt O'Dowd?

  I saw, I saw an aurora. You know, it was faint and it was, you know, but it filled the horizon. And, you know, you could see the curtains shifting very slowly.

• 22:58Neil deGrasse Tyson?

  Nice, nice. Did you see colors? Or just the colors?

• 23:02Matt O'Dowd?

  Once my, yeah, once our eyes had really adapted, we could, we could see a little bit, but.

• 23:08Neil deGrasse Tyson?

  And what's your location now on Earth?

• 23:09Matt O'Dowd?

  We're upstate, upstate New York.

• 23:12Neil deGrasse Tyson?

  Upstate New York. Yeah, so far away from city lights.

• 23:14Chuck Nice?

  Yeah, exactly. Yeah.

• 23:15Neil deGrasse Tyson?

  So that wasn't just the Empire State Building.

• 23:20Matt O'Dowd?

  Oh, damn.

• 23:20Neil deGrasse Tyson?

  Cause the, cause the Yankees won or something. Okay. Just checking.

• 23:24Chuck Nice?

  So anyway, and it's 20 times, they say, the size of the Earth. But then when you think about it, how many Earths can you fit inside the sun?

• 23:31Matt O'Dowd?

  Hundred, hundred and ten in diameter. What, a million in volume? But, yeah.

• 23:37Neil deGrasse Tyson?

  Yeah, yeah, yeah. A hundred across times a cube is a million, right?

• 23:41Chuck Nice?

  So you could put a million suns inside the entire ball.

• 23:45Neil deGrasse Tyson?

  No, a million Earths.

• 23:46Chuck Nice?

  A million Earths. I'm sorry, a million Earths inside the buyer, the ball that is the sun. But you would see a, a, what'd you say, a hundred Earths going straight across?

• 23:56Matt O'Dowd?

  Yeah.

• 23:57Neil deGrasse Tyson?

  Yeah, about that. But I'm saying, I'm saying, you know, if the sun can hold a million Earths, what are you worried about for a whole 20 times?

• 24:03Chuck Nice?

  Exactly, for 20, yeah, 20 times the size, big deal.

• 24:07Matt O'Dowd?

  That's 20, that's 20% of the diameter. That's not a small hole, but. But, uh, you know, seems to be shining still. I think we have another part of this question that I actually have some expertise in.

• 24:18Neil deGrasse Tyson?

  Yeah, let's do it. Yeah. So the rest of it.

• 24:21Matt O'Dowd?

  All right. So, uh, can you, can you have quasars that, uh, that are small? Like, you know, you can have relatively small black holes. Can they become quasars in the right circumstances? Well, sort of. So, uh, any size, any decent sized black hole can form what we call an accretion disk around it. So if you get gas close enough, the gas will form this whirlpool of material that's, that's swirling into the black hole. The whirlpool will heat up and it's from that heat glow that you get the, the super bright quasar. Now, a quasar and the related, what we call active galactic nuclei are when you have a black hole in the center of a galaxy and, and they're big. But there are.

• 25:03Matt O'Dowd?

  Smaller black holes, what we call stellar mass black holes that are left over after a massive star dies. And these might be, you know, 10 times the mass of the sun, you know, up to, you know, several tens times the mass of the sun. And these things can form what look like mini quasars, but it's in a very special circumstance. And that's when that black hole happens to fall into a binary orbit or to have formed in the binary orbit with another star. Okay, now if those, if, if those stars get too close, then the envelope of the living star can spill over into the influence of the black hole and

• 25:41Chuck Nice?

  Of the black hole.

• 25:41Matt O'Dowd?

  Starts getting

• 25:42Chuck Nice?

  So is the black hole eating that star? Is it, is it slowly siphoning off and eating that star?

• 25:47Neil deGrasse Tyson?

  It's flaying the star.

• 25:48Matt O'Dowd?

  Exactly.

• 25:49Chuck Nice?

  Flaying.

• 25:50Matt O'Dowd?

  Cannibalizing, vampirizing, something. It's eating the star.

• 25:54Neil deGrasse Tyson?

  Well, I love that vampirizing. I love that. That's definitely what it's doing.

• 25:57Matt O'Dowd?

  Sucking its life out. And then, so you get an accretion disk that's relatively small compared to, you know, a quasar, but it's still, you know, solar system size, it's still big. And these are called X-ray binaries because we first saw them from the bright X-ray light that they emit. And, and these we see through the universe, even in the Milky Way. The nearest one is the, um, the Cygnus X1 black hole, which is about a thousand light years away. Okay, so, uh, so we do get mini quasars.

• 26:29Neil deGrasse Tyson?

  So these are basically nearby baby quasars.

• 26:32Matt O'Dowd?

  Well, baby, except they're not going to grow up to be adult quasars.

• 26:35Neil deGrasse Tyson?

  Oh, yeah. Okay. What would you say is the threshold between just an active galactic nucleus and what we officially would label as a quasar?

• 26:45Matt O'Dowd?

  Yeah, it's a, you know, the definitions are muddy because these things are very far away and they, they all, all, all these active galactic nuclei look a bit different depending on, you know, how much gas is going in, how big the black hole is, even what is the orientation of the accretion disk. At some angles, we don't even see it because there's a bunch of gunk surrounding it that blocks it, blocks it.

• 27:08Neil deGrasse Tyson?

  So there could be galaxies that are quasars for some parts of the universe and not for others?

• 27:14Matt O'Dowd?

  Yeah, absolutely. Yeah.

• 27:15Neil deGrasse Tyson?

  Yeah, okay. That's interesting. So it's an orientation thing.

• 27:17Matt O'Dowd?

  Exactly. Um, but the threshold for a quasar, it's essentially a very luminous active galactic nucleus that we, in which we can see the accretion disk. So you have, you have these two, two, you know, Parameters, the luminosity, which is partially driven by the black hole mass. Okay, be a black hole mass can support a big disk is complicated.

• 27:37Neil deGrasse Tyson?

  Now, Matt, what I heard is it's still true because it's been a while since I've looked at this. That the reason why quasars are all far away is because nearby galaxies that may have once been quasars ate all of their gas.

• 27:52Chuck Nice?

  Right.

• 27:52Neil deGrasse Tyson?

  They completely consumed their accretion disk. So there's nothing left to radiate.

• 27:56Chuck Nice?

  Get in my belly.

• 27:57Neil deGrasse Tyson?

  They've eaten it. Is this a fair, is that a, because the quasars at the edge of the universe, that's long ago.

• 28:03Matt O'Dowd?

  Yeah.

• 28:04Neil deGrasse Tyson?

  And far away in a galaxy, far, far away. The nearby galaxies have done lived their early lives, done eaten their, and so there, we don't have a prevalence of quasars nearby. Is that understanding still accurate?

• 28:17Matt O'Dowd?

  The, the short answer is you're totally right. The longer answer is you're partially right. Uh, and there's another effect. So it's true that, that the universe went through something that we call the quasar epoch, which was like, you know, ended a few billion years ago, uh, and, and the quasars. So there was this kind of middle period of, of the universe's life where the quasars flared up in the, the biggest galaxies that exist in the universe. And that basically corresponded to when those galaxies were being built. Okay. So as, you know, the big bang happened, galaxies started being built and there was this.

• 28:55Neil deGrasse Tyson?

  So there was a, a supply of food.

• 28:57Matt O'Dowd?

  A supply of food for the biggest galaxies, which had the biggest black holes. Nowadays, those galaxies are, are basically done being built and more of the galaxy building action is for the lower mass galaxies, like, you know, some spiral galaxies, a bit more like the Milky Way. And these things don't tend to create big quasars. But the other, the other effect is that, you know, quasar, like full blown quasars, aren't that common in the universe. And so we don't, you know, we don't even have a galaxy that would have been one very close to us.

• 29:31Chuck Nice?

  Right.

• 29:32Neil deGrasse Tyson?

  Mm hmm.

• 29:33Chuck Nice?

  So now, now you say they're not that, uh, prevalent, um, or, um, common in the universe.

• 29:41Chuck Nice?

  Could there still be a lot more that we haven't seen? Just because, how much of the night sky have we actually seen? You know what I mean? Like, can you? Or does it work out that what we have seen, you can extrapolate and say that we're going to see that exact amount if we were to see everything?

• 30:00Matt O'Dowd?

  Yeah, I mean, I think you answered the question, Chuck, so thanks. But, but, you know, we've seen a lot of the universe. Our surveys have scanned a huge volume of the universe. It's hard, it's hard to look directly through the disk of the Milky Way because there's too much stuff in the way. But, but above and below, we've seen a lot. And we've found many hundreds of thousands of quasars there. So I say they're not common, but the universe is big.

• 30:25Chuck Nice?

  But we see them, okay.

• 30:26Neil deGrasse Tyson?

  Yeah, it's big, a big universe. Rare things are common.

• 30:29Matt O'Dowd?

  Yeah. Or abundant or something, yeah.

• 30:32Chuck Nice?

  Yeah.

• 30:36Chuck Nice?

  It makes perfect sense.

• 30:37Neil deGrasse Tyson?

  Makes perfect sense, right?

• 30:38Chuck Nice?

  It makes, it just makes perfect sense. Simpler than that. All right.

• 30:43Neil deGrasse Tyson?

  Well, just to be clear, if one in a million people is seven feet tall, then in a country of 300 million people, they're 307 foot taller. So.

• 30:52Matt O'Dowd?

  You still might not get on the basketball team. You're right.

• 30:54Neil deGrasse Tyson?

  Yeah, the, the, the big numbers bail you out of that.

• 30:58Chuck Nice?

  Right, exactly.

• 30:59Neil deGrasse Tyson?

  And of course, what's the adjective we have for big numbers? They would be astronomical, yes.

• 31:06Chuck Nice?

  Ah.

• 31:08Matt O'Dowd?

  We, we kind of corner the big numbers, don't we, Neil?

• 31:10Neil deGrasse Tyson?

  Yeah, we totally own the big numbers.

• 31:13Matt O'Dowd?

  We got all the big numbers.

• 31:14Chuck Nice?

  That's for sure.

• 31:16Matt O'Dowd?

  Biggest numbers.

• 31:17Neil deGrasse Tyson?

  All right, give me another one.

• 31:18Chuck Nice?

  This is Cameron Bellamy. He says, greetings from Baltimore, Maryland. On this show, Neil has talked about the consequences of our expanding universe and its eventual big rip. I'm curious how this phenomenon will affect black holes. From my understanding, black holes are super dense matter. And spacetime expands. Will the super dense black holes become less dense until eventually representing matter density similar to what the rest of the universe has and thereby being able to be ripped? Will the opportunity for life arise from what was once a black hole as the

• 31:59Chuck Nice?

  universe expands in the far distant future?

• 32:04Neil deGrasse Tyson?

  Damn, my boy's thinking about this.

• 32:06Chuck Nice?

  Let me tell you, this question he should have, he should have followed up with. And it only took me one year to think of this question.

• 32:17Neil deGrasse Tyson?

  All right, we're gonna pick up the answer to that at the beginning of segment three, right after this break.

• 32:35Neil deGrasse Tyson?

  We're back, Cosmic Queries, based on the expertise of my friend and colleague, Matt O'Dowd, who teaches at Lehman College of the City University of New York. And Matt, how do we find you on social media? Beyond your YouTube channel, which has three million followers?

• 32:51Matt O'Dowd?

  Yeah, so you could go to PBS Spacetime and just watch me talk about space and quantum mechanics and everything physics.

• 32:59Neil deGrasse Tyson?

  All good. I've seen episodes. You're great. You're totally there, friendly and informative, and I always want more when I see it. So congratulations on what you've created there.

• 33:08Matt O'Dowd?

  Appreciate that.

• 33:08Neil deGrasse Tyson?

  And it's a part of the PBS universe.

• 33:10Matt O'Dowd?

  Yeah, yeah, it's a PBS show. PBS Digital Studios, to be precise. Otherwise, I am MattOfEarth on Twitter and on Instagram.

• 33:26Neil deGrasse Tyson?

  Matt of?

• 33:27Chuck Nice?

  Matt of Earth.

• 33:28Matt O'Dowd?

  Of Earth, yeah.

• 33:29Neil deGrasse Tyson?

  Earth, Earth.

• 33:30Chuck Nice?

  This is Earth's Matt.

• 33:31Matt O'Dowd?

  This is Earth's Matt, yeah.

• 33:33Chuck Nice?

  Okay.

• 33:33Neil deGrasse Tyson?

  Mars has its own Matt.

• 33:35Matt O'Dowd?

  Just in case people are wondering, you know.

• 33:38Neil deGrasse Tyson?

  All right, we're picking up where we left off.

• 33:40Chuck Nice?

  Before we left, we had Cameron Bellamy, who basically was saying, when you look at the big rip, and you consider black holes.

• 33:45Neil deGrasse Tyson?

  Will it affect black holes? Yeah.

• 33:46Chuck Nice?

  Will it affect black holes? And does it affect them differently because they're such, they're so dense?

• 33:52Neil deGrasse Tyson?

  Yeah, what do you know about that?

• 33:53Matt O'Dowd?

  Yeah, so this is pretty speculative, but I'm gonna take my best guess. So the big rip is probably, probably not gonna happen. It only happens if dark energy is something more exotic than most physicists think it is. If, if the strength of dark energy increases over time, then eventually the accelerating expansion of the universe can affect smaller and smaller regions. Eventually, subatomic scales tearing everything apart, blah blah. Okay, so if that's the case, then it would affect black holes, I think. Because black holes contain space, and that's, if that space contains a, an increasing amount of dark energy, that dark energy has an anti-gravitational effect.

• 34:38Matt O'Dowd?

  Um, I think what it would do would be, would be to cause black holes to evaporate more quickly. That would, that would be my guess. So black holes are evaporating, as we learned by Hawking radiation, my guess. So the event horizon's shrinking. So my guess is that a, a big rip style dark energy would, would cause that, that evaporation to happen more quickly.

• 34:59Neil deGrasse Tyson?

  So my guess, I like to hear what you said there. My guess is that the opposite will happen, is that they'll evaporate less quickly because Oh! the expansion dilutes the energy density in their environment.

• 35:12Chuck Nice?

  Around the, around the black hole.

• 35:14Neil deGrasse Tyson?

  And which will make it less likely to produce the particles. However, what you said was, seems to be all in, where the black hole volume is made of spacetime, like anything outside the volume. And it's spacetime that's getting stretched. So I can imagine the big rip simply Unzipping black holes.

• 35:35Matt O'Dowd?

  Right.

• 35:36Neil deGrasse Tyson?

  Right? And because it's stretching them out so that they don't no longer have their black hole event horizon density.

• 35:45Matt O'Dowd?

  Yeah, I bet someone who's calculated this, I need to.

• 35:49Neil deGrasse Tyson?

  Yeah, so I haven't, I haven't calculated and but but some combination of our two answers sound like.

• 35:54Matt O'Dowd?

  Exactly.

• 35:55Chuck Nice?

  Now, let's get back real quick, because I know we don't have a lot of time left in the show, because we got to get to more questions.

• 36:00Neil deGrasse Tyson?

  Good.

• 36:00Chuck Nice?

  Please go back to why the big rip is not going to happen, because you're the first

• 36:05Neil deGrasse Tyson?

  No, no, no, it will happen if the strength of this dark energy grows relative to gravity as the universe expands.

• 36:14Chuck Nice?

  Oh, okay.

• 36:14Neil deGrasse Tyson?

  It will happen.

• 36:15Chuck Nice?

  Will.

• 36:15Neil deGrasse Tyson?

  What Matt was saying is, we're not entirely sure that dark energy will grow in strength as the universe expands relative. Is that what, did I characterize it correctly?

• 36:26Matt O'Dowd?

  Yeah, the default model for dark energy is that it maintains a constant energy density.

• 36:30Chuck Nice?

  Maintains a constant, okay, I got you. Now, I'm totally straight now. Okay, great.

• 36:34Neil deGrasse Tyson?

  Okay.

• 36:35Chuck Nice?

  That's awesome. All right, let's go to our friend Alejandro Reynoso.

• 36:46Neil deGrasse Tyson?

  I have to assume he's not offended by this, Chuck, because otherwise we would have gotten mail from him by now.

• 36:51Chuck Nice?

  We have not. As a matter of fact, we have not received any cease and desist orders from Alejandro Reynoso. So Alejandro Reynoso says.

• 37:04Neil deGrasse Tyson?

  But, so, yeah, so the authorities haven't shown up at your door. They haven't, okay. And where's he from, Chuck?

• 37:11Chuck Nice?

  This is Alejandro Reynoso from Monterrey, Mexico. And he says, hello.

• 37:19Neil deGrasse Tyson?

  Okay.

• 37:20Chuck Nice?

  Or should I say hola? Now, then he says, my question is, how do you use gravitational lensing in your observations? It is actually, does it actually let you see distant objects clearly? Or do you need to make many adjustments to come up with your image? So how are you utilizing gravitational lensing?

• 37:42Neil deGrasse Tyson?

  Yeah, Matt, Matt, what does your object look like after it's been gravitationally lensed?

• 37:46Matt O'Dowd?

  Great. I love this question, because I know, I know about it. Um, one, so.

• 37:52Matt O'Dowd?

  So.

• 37:55Matt O'Dowd?

  The Einstein guy again predicted that gravitational fields bend the paths of path of light, you know, bend the fabric of spacetime. And so you look out there in the universe and you see that distant objects aren't necessarily where they appear to be, particularly if there's something big like a whole galaxy between you and that object. And the things that I'm interested in are gravitationally lensed quasars, there we go, quasars again, where you have a distant quasar, an intervening galaxy, and you just happen to be perfectly lined up so that the light from that distant quasar is deflected by the gravitational field and comes back towards us. And so we

• 38:36Matt O'Dowd?

  actually see the same quasar through multiple paths through space. We get light from multiple different paths through space. So you actually look like you see two images or four images, but really there's always an odd number of images. And that's because in between the two images or the four images, there's a tiny little image of the original object. Normally, you can't see that because you've got this great big galaxy or whatever is doing the lensing in the way. But yeah, fun fact, you always get an odd number of images with gravitational lensing. So, so my interest is in trying to use gravitational lensing to probe the inner

• 39:18Matt O'Dowd?

  structure of those quasars. So you have this giant accretion disk around the black hole, but really these things are so far away that there's no telescope that we can even imagine building that'll be able to take a real picture of a quasar and see that in a structure. But in the case of gravitational lensing, you can basically reconstruct what the quasar looks like because you have one more effect at play. So the lens, if it's a galaxy, is a pretty crappy lens. It's made of stars. And because everything in the universe is moving relative to each other, you see occasionally, you'll get this extra special alignment of a star inside the lensing

• 39:57Matt O'Dowd?

  galaxy with one of these, one of these pathways. So one of these pathways might pass in the gravitational field of an individual star with such an alignment that it... That that one image grows in brightness and then shrinks again. And so over time, you see these, you know, let's say there are four images, you see them flicker on different time scales. And from that flickering, you can actually reconstruct the inner structure of the quasar because the the rate of the flickering depends on on how big the quasar is. And so you can sort of map it out in this way.

• 40:31Neil deGrasse Tyson?

  Hmm. And and I I remember I was active in graduate school when this first measurement was made, where someone looked at one of the lensed quasars and and it it flared in some way. And then they waited for the other image to flare.

• 40:48Matt O'Dowd?

  That's

• 40:48Neil deGrasse Tyson?

  And it flared in exactly the same way.

• 40:50Matt O'Dowd?

  That's crazy.

• 40:51Neil deGrasse Tyson?

  And that time delay was the path length difference between one direction around the object and the other. I mean, it was a brilliant thing. Everyone was sitting around waiting for it and bada bing.

• 41:02Matt O'Dowd?

  Yep.

• 41:02Neil deGrasse Tyson?

  There it is.

• 41:03Matt O'Dowd?

  That is really cool.

• 41:04Chuck Nice?

  And you know what?

• 41:05Neil deGrasse Tyson?

  That's how you knew it was the same object.

• 41:07Matt O'Dowd?

  It had to be the same. It was just on a delay.

• 41:09Neil deGrasse Tyson?

  It was on a time delay.

• 41:09Matt O'Dowd?

  Because it did the exact, wow.

• 41:10Neil deGrasse Tyson?

  Exactly the same thing.

• 41:11Matt O'Dowd?

  Wow.

• 41:12Chuck Nice?

  I know, I know.

• 41:13Neil deGrasse Tyson?

  Damn. The same way.

• 41:14Matt O'Dowd?

  That is so cool.

• 41:16Neil deGrasse Tyson?

  Because initially, you don't know what it's this object in the image.

• 41:20Matt O'Dowd?

  Right.

• 41:20Neil deGrasse Tyson?

  And so I was in graduate school when that happened. That's how old I am, Matt. I'm like decades older than you. So I remember when this stuff was

• 41:28Matt O'Dowd?

  Well, you know, you know, this, that, that, that exact thing, like measuring the different path lengths is going to be one of the ways that we actually figure out what dark energy is. Because if you can measure those different path lengths, you can get the distances to the, to the lens, to the, to the quasar. And so you can actually map the expansion history of the universe by getting those distances. And that's one of the ways we might be able to to figure out the rate at which the universe is accelerating.

• 41:56Chuck Nice?

  Right.

• 41:57Matt O'Dowd?

  Mm hmm.

• 41:57Chuck Nice?

  Because, oh, my God, that's it. Because the universe is actually not just expanding at a constant rate, it's speeding up. So when you're able to get those distances and see the differences on the delay, you can actually kind of calculate the dark energy because that's what's behind it, right?

• 42:13Neil deGrasse Tyson?

  Yeah.

• 42:13Chuck Nice?

  Damn. Oh, God. Science is amazing.

• 42:22Chuck Nice?

  Wow. Okay. Okay, that's amazing.

• 42:26Neil deGrasse Tyson?

  No, but we still, there's still people who walk among us and say, I don't know science.

• 42:32Chuck Nice?

  What is wrong with people? What is wrong with people?

• 42:36Neil deGrasse Tyson?

  We're figuring out the time delay through different path lengths around a lensed galaxy across 80% of the universe, and you're saying, I'm not science.

• 42:45Chuck Nice?

  If that doesn't get you nothing, well, that is some amazing stuff right there. All right, here we go. This is Renee Spur. Renee, Renee Spur says, hey, guys, I just heard about the red star, uh, Octorus, and that I could have a planet or substellar object orbiting it 12 times larger than Jupiter. About a month ago, you had a guest on that said Jupiter was the largest planet ever discovered. So what do you think could be orbiting? Can't wait to hear the answer. Thanks from Orange County, California, Renee.

• 43:19Neil deGrasse Tyson?

  Okay, I don't know that we had a guest that said Jupiter was the largest planet ever, because it's definitely not. All right? Plenty of other planets in the exoplanet catalog are bigger than Jupiter. The difference is, if you start getting much bigger than Jupiter, we don't really call them planets anymore, right? I mean, they're like brown dwarfs. We have other vocabulary for them. So that's really what's going on here.

• 43:41Chuck Nice?

  They're failed stars.

• 43:43Neil deGrasse Tyson?

  Failed star. Matt, do you have any insight into that question?

• 43:45Matt O'Dowd?

  Yeah, I mean, I'm not aware of this result, but 10 times larger, 12 times larger than Jupiter is really getting on the verge of the smallest star level. Well, 100. So it's a brown dwarf. So the question is, is it a planet or is it a failed star? And I think the answer is it depends on how it formed. You know, if, if, if they, if the two form together by, you know, collapsing from the same giant cloud of gas and finding each other, then it's a binary star system. One of them's just a failed star. If the the big star formed first and then this giant Jupiter formed in the disk of leftovers around that star, then you might call it a giant planet. But.

• 44:26Neil deGrasse Tyson?

  Yeah, so the origin story matters. The origin story matters, it sounds like.

• 44:30Chuck Nice?

  That makes sense. So one's cleaning up stuff.

• 44:33Neil deGrasse Tyson?

  Yeah, exactly.

• 44:34Chuck Nice?

  And the other was.

• 44:35Neil deGrasse Tyson?

  The other one is out of the same birth sack.

• 44:37Chuck Nice?

  Right. Wow, okay, cool, man. Yo, that that that was a cool question, Renee, thanks.

• 44:43Neil deGrasse Tyson?

  All right.

• 44:44Chuck Nice?

  Take it. Um, here we go. Tricia Lynch says hello and greetings from Beaverton, Oregon. My question is, what would happen if galaxies stop rotating? What? What happens?

• 44:57Matt O'Dowd?

  It wouldn't be good, let me tell you that.

• 45:01Chuck Nice?

  Next question. There you go. Thank you, folks, and good night. There you go, Tricia. Hope you can sleep.

• 45:07Neil deGrasse Tyson?

  No, no, no, I got one. I'm gonna tee up, I'm gonna tee up Matt on this one. You ready? So if the Milky Way stopped rotating today, then every single star would fall to the center.

• 45:21Matt O'Dowd?

  Immediately.

• 45:22Neil deGrasse Tyson?

  Because it's its orbital speed that's maintaining our distance. Without that orbital speed, they will fall to the center. And Matt, what do you have waiting for everybody at the center? Behind door number one, Matt.

• 45:33Matt O'Dowd?

  My favorite cosmic friend, the supermassive black hole.

• 45:37Chuck Nice?

  There you go.

• 45:38Matt O'Dowd?

  Sagittarius A star, four million suns worth of black hole. And, I mean, if they really stopped perfectly, then technically, everything would, well, yeah, it would be a mess, it would be a mess.

• 45:52Neil deGrasse Tyson?

  It would be go straight to that black hole.

• 45:53Matt O'Dowd?

  It's the black hole.

• 45:54Neil deGrasse Tyson?

  It wouldn't be four million, it would be billions of times the mass of the sun.

• 45:56Matt O'Dowd?

  Is the black hole exactly in the center of the Milky Way? I'm not sure, I'm not sure. So they might, they might, they might do close, you know, everything would would end up in these

• 46:06Neil deGrasse Tyson?

  I don't know if it's exactly in the center, good question.

• 46:08Matt O'Dowd?

  Things, but there'd be collisions and.

• 46:10Neil deGrasse Tyson?

  Yeah, it would be bad. All around and and the whole galaxy could just be eaten by the black hole at that point. That would that would be interesting.

• 46:18Chuck Nice?

  Wow, all right. Yeah, that's that's.

• 46:21Neil deGrasse Tyson?

  That'd be something Thanos would do.

• 46:22Chuck Nice?

  That would be just, yeah.

• 46:25Neil deGrasse Tyson?

  Don't you don't like me when I'm angry.

• 46:26Chuck Nice?

  Snap a finger, he actually claps like.

• 46:30Chuck Nice?

  Like like the clapper that turns the lights off. And then everything just falls to the supermassive black hole in the center of the galaxy.

• 46:37Neil deGrasse Tyson?

  Or the choreographer on Broadway. Step up to the.

• 46:44Neil deGrasse Tyson?

  Yeah, that would be that's how to destroy a galaxy on the spot and make a supermassive, super duper massive black hole.

• 46:50Chuck Nice?

  Look at that. All right, here we go. Ignacio Karasconi says, or how Cara Caracasoni says, hey, greetings from Brooklyn, New York. My kid and I are fans of the show. That's right. And we have been to.

• 47:06Neil deGrasse Tyson?

  He and who are fans?

• 47:08Chuck Nice?

  My kid and I are fans of the show and we have been to the Hayden Planetarium at least a dozen times. So my question for Matthew, Neil, and hello Chuck, uh, yeah, he ain't asking me anything.

• 47:24Neil deGrasse Tyson?

  Okay.

• 47:26Chuck Nice?

  He says, why is solar gravitational lens mission hasn't happened yet? And when is it likely one of the most powerful tools to study exoplanets and find life besides our local sample? When will that happen?

• 47:44Matt O'Dowd?

  You know, I think.

• 47:46Neil deGrasse Tyson?

  Matt, do you think he's talking about um, uh, the the lensing that Bodhan Pachinsky was doing, the um, micro lensing? Do you think that's what he's talking about there?

• 47:55Matt O'Dowd?

  This is a plan to um, send out a little telescope to a point in the outer solar system. So there's a point in way out beyond. Uh, you know Neptune, uh, I was gonna say Pluto, then I realized you were here, Neil.

• 48:13Neil deGrasse Tyson?

  Yeah, yeah.

• 48:14Matt O'Dowd?

  Way beyond Neptune. And so there's this point where, uh, and so you've got the sun. The sun is a big gravitational object. It bends the path of light and there's this region. Um, can't remember how far away it is. It's like a, you know, a week light travel time away or something like that, where light from a distant object will come to a focus due to the sun's gravitational field. And if you could put a telescope in this, basically this focal range.

• 48:44Neil deGrasse Tyson?

  I remember this telescope.

• 48:45Matt O'Dowd?

  Yeah, yeah, yeah. This, this, this, this sort of, you know, and it extends over a certain range because it depends on how far away the, um, the, the object is. But if you put a telescope there, then, then the sun would become an extra lens on that telescope. And it would produce such powerful magnification that you could see. So the calculations go. A, a single planet orbiting around a distant star, which is something that is extremely difficult for us to do, but.

• 49:15Neil deGrasse Tyson?

  I remember this, but then it's, I didn't, then I stopped reading about it. So has this idea gone away?

• 49:20Matt O'Dowd?

  No, it hasn't gone away. You know, people have been thinking about it for a long time and are still, like, I, I, I hear people talking about it and, and, and that we should do it.

• 49:31Neil deGrasse Tyson?

  But wait, but Matt, isn't the sun in the way? How are you gonna see a lensed planet when the sun is brighter than everything? Like, it's like trying to find a firefly in a, in a Hollywood searchlight.

• 49:42Matt O'Dowd?

  Yeah.

• 49:43Neil deGrasse Tyson?

  How does this actually work? I, I, I agree and I see where you get the magnification effect. That would be amazing. I get that. But there's still the matter of this, I guess you have to have some kind of like a, uh, some kind of disc that blocks the sunlight.

• 49:56Matt O'Dowd?

  Yeah.

• 49:56Neil deGrasse Tyson?

  In the telescope, you'd have to have something like that.

• 49:58Matt O'Dowd?

  I love it when you ask me a question and then answer it perfectly. Uh, so, I mean, you know, the, the.

• 50:04Neil deGrasse Tyson?

  I'm just thinking it up on the fly.

• 50:05Matt O'Dowd?

  You know, I'm sure you know about coronagraphs, we call them, which are.

• 50:08Neil deGrasse Tyson?

  Yeah, yeah, yeah, yeah.

• 50:09Matt O'Dowd?

  So you would, and there are, uh, uh, you know, ideas about how you would build these giant coronagraphs. Basically a, a big. Circle, but there are also various interesting, complex things that would unfurl in front of this distant telescope that would block the sunlight. And so you could see this, you know, basically this ring. So what it would look like would be the sun blotted out, but then surrounding the sun, this perfect ring, what we call an Einstein ring. And that perfect ring would be the exoplanet. Okay, so if it were another, you know, another civilization doing this for the earth,

• 50:49Matt O'Dowd?

  they would use their star to look at the earth if they just happened to be in the right position to do that. And then Earth's structure would be smeared around. But to the level that if you reconstruct it, and you could reconstruct it just by, you know, using good old Einstein general relativity to figure out what the image looked like, you know.

• 51:12Neil deGrasse Tyson?

  Yeah, so anybody could do it.

• 51:13Matt O'Dowd?

  Yeah, anybody could do it, literally, literally anybody. You could, you could see, you know, continental coastlines down to, I can't remember the exact scale of it, you know, kilometers or something like that. So you could literally map the surface of that distant planet.

• 51:28Neil deGrasse Tyson?

  But you'd have to reconstruct the sphere from the smeared circle.

• 51:32Matt O'Dowd?

  Exactly, yeah.

• 51:33Neil deGrasse Tyson?

  The visual image from that, right. So that'd be what a task that would be. I forgot all about that telescope. Matt, thanks for reminding me of that.

• 51:40Chuck Nice?

  I gotta tell you the truth, it sounds like the worst camera ever. I'm sorry. It really does. I don't, I don't want to be a hater, but I'm just saying.

• 51:48Neil deGrasse Tyson?

  Chuck hatin' on the most advanced system.

• 51:52Chuck Nice?

  No, I'm joking.

• 51:53Neil deGrasse Tyson?

  So Matt, we gotta call it, we gotta call it quits there. Man, that was fast.

• 51:57Matt O'Dowd?

  I'm sad, but.

• 51:58Neil deGrasse Tyson?

  All right.

• 51:59Chuck Nice?

  Well, you know what, let me give you one quick one because this guy is personal and professional, this question. It's a personal professional question. This is David Lee's or Les', and he says, hello, Dr. O'Dell. Have there been any surprise findings in your research that have shaken up your understanding of astrophysics?

• 52:15Matt O'Dowd?

  In my personal research.

• 52:17Chuck Nice?

  And your personal research.

• 52:18Matt O'Dowd?

  I wish.

• 52:20Matt O'Dowd?

  In my personal research, have I shaken up the understanding of my, oh, man. Now, now I'm going to get sad because I, I don't think I have personally. Revolutionized my own understanding.

• 52:36Matt O'Dowd?

  You know, there have been things that have surprised me. There's been objects that I've studied that have surprised the hell out of me. Gravitational lenses that have done things that I really didn't expect them to. I've managed to, I have managed to find ways to look at the interiors of quasars that, that, that are relatively new and found.

• 52:56Neil deGrasse Tyson?

  Sounds good.

• 52:57Matt O'Dowd?

  Found things like.

• 52:57Chuck Nice?

  Yeah, that's good.

• 52:58Matt O'Dowd?

  Like.

• 52:59Neil deGrasse Tyson?

  So it's not a new object, it's a new tactic.

• 53:01Matt O'Dowd?

  Yeah, yeah, yeah, yeah. You tactics.

• 53:03Neil deGrasse Tyson?

  It works too.

• 53:03Chuck Nice?

  You're a little hard on yourself there, Matt.

• 53:05Neil deGrasse Tyson?

  I know, right.

• 53:05Chuck Nice?

  You're a little hard on yourself.

• 53:07Matt O'Dowd?

  He's in weird stuff out there.

• 53:10Chuck Nice?

  And for everybody listening, you just found out the heart of every scientist right there in that question and answer. Because scientists, what they don't want to do is succeed. What they want to do is look down and go, what the F is that? What? What the F is that? Oh my God, come over here. What is that? That's true. That's what gets scientists all freaked out.

• 53:33Neil deGrasse Tyson?

  That's how it works. Yeah. It's not, it's not to discover what you know.

• 53:37Chuck Nice?

  Right.

• 53:37Neil deGrasse Tyson?

  Finding something you have no idea what the hell you're looking at. Right. Right.

• 53:41Chuck Nice?

  So, all right.

• 53:42Neil deGrasse Tyson?

  All right, dudes, we got to call it quits there. So thank you for yet another episode of StarTalk Cosmic Queries. Neil deGrasse Tyson here, as always, bidding you to keep looking up.