Cosmic Queries: Dark Matter and Dark Energy

Dark matter is the longest unsolved problem in astrophysics. Find out what we know – and what we don’t – from your own personal astrophysicist, Neil deGrasse Tyson.

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

• 0:01Neil deGrasse Tyson?

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

• 0:21Neil deGrasse Tyson?

  This is StarTalk. I'm Neil deGrasse Tyson, your personal astrophysicist, and this is the Cosmic Queries edition. I have with me Leanne Lord. Leanne, welcome back to StarTalk.

• 0:33Speaker 01

  Thank you. Hey.

• 0:34Neil deGrasse Tyson?

  This is Cosmic Queries. It's not your first rodeo here.

• 0:37Speaker 01

  No, not at all. I'm experienced.

• 0:39Neil deGrasse Tyson?

  Thank you. And so to remind some listeners, perhaps for the, or tell you for the first time, we, in the Cosmic Queries editions, we solicit questions from all of our web presence, our social media presence, and a comedian, in this case you, call through them and just send them my way.

• 0:58Speaker 01

  Yes.

• 0:59Neil deGrasse Tyson?

  And so, let's go ahead and do that.

• 1:01Speaker 01

  Okay. And, and we do remind people that you have not seen these in advance.

• 1:05Neil deGrasse Tyson?

  No, it's, and it's, the point is not to stump me or anything. It's just, yeah, it's just I haven't seen them. So, so if I don't know something, I'll just tell you.

• 1:11Speaker 01

  You're not just gonna make it up?

• 1:12Neil deGrasse Tyson?

  I'm just, I can do that too.

• 1:14Speaker 01

  Okay. If you pass, I'll, I'll, I'll answer it. What? Well, that's a disaster.

• 1:18Neil deGrasse Tyson?

  Exactly. Yeah. Leanne, you take it.

• 1:19Speaker 01

  (laughing) Crickets.

• 1:20Neil deGrasse Tyson?

  All right. So, what do you got?

• 1:21Speaker 01

  Okay.

• 1:22Neil deGrasse Tyson?

  So, this is probably a papery. I mean, we're not, not one subject or all. It's just on all the universe in this segment.

• 1:28Speaker 01

  Well, um, we are, I guess, discussing dark matter and dark energy.

• 1:31Neil deGrasse Tyson?

  Oh, dark, oh, that's fine. Okay.

• 1:32Speaker 01

  And I, at first, took it personally until someone said, "No, we're not talking about you."

• 1:36Neil deGrasse Tyson?

  Okay.

• 1:37Speaker 01

  So, the first question is from Rocky Cofrin, and, uh...

• 1:44Neil deGrasse Tyson?

  You gotta admit, that's a cool name, Rocky.

• 1:45Speaker 01

  It is. It is pretty cool. And I actually now don't know if that's a he or she.

• 1:48Neil deGrasse Tyson?

  Uh, is that what, through what, the social media source did that come?

• 1:52Speaker 01

  I believe this is from Facebook.

• 1:53Neil deGrasse Tyson?

  Facebook, good.

• 1:54Speaker 01

  Because if it were Twitter, it'd be only 140 characters.

• 1:56Neil deGrasse Tyson?

  Okay.

• 1:57Speaker 01

  So, it's a little longer than that.

• 1:58Neil deGrasse Tyson?

  That's a long question. Go for it.

• 2:00Speaker 01

  That's a short question. Okay. "I've seen graphs and heard percentages of what makes up the universe. Uh, somewhere around 80% dark energy, 16% dark matter, and 4% everything else. My question is, how did we come to these numbers? What instruments were used to make that conclusion?"

• 2:17Neil deGrasse Tyson?

  Nice. Well, first of all, I mean, dark matter is we, you know, most of the gravity we measure in the universe has no known origin. Everything we we know that makes gravity, Mm hmm. like matter and gas clouds and energy and all these things, you add it all up, it doesn't account for all the gravity we see. So that's like the dark. So there's missing stuff. There's it used to be called missing matter. It used to be called that. And we say, well, how do you know it's missing? How do you know it should have been there in the first place? Right. So it's really, it's really too much gravity is what we should call it, not missing matter. Because maybe gravity comes from other kinds of things. So you can add up how much of that is driving the universe. Okay. Right? And put put that in a box. And then you say, hey, the universe wants to to sort

• 3:00Neil deGrasse Tyson?

  of slow down in its expansion because there's all this gravity, yet it's accelerating in its expansion. There's some mysterious pressure in the vacuum of space pushing on the universe. That takes a certain amount of energy to do. Okay. You you put that put that in a box. You add those two together. It is ninety six percent of everything that matters, no pun intended, in the universe. Okay. And so everything we know, all of our laws of physics, all of our understanding of the behavior of matter, motion and energy is four percent of the universe. We understand. We understand four percent of the universe of what's driving the universe. And that's the chart. This is a pie chart. It like cut away four percent of an apple pie. Mm hmm.

• 3:42Neil deGrasse Tyson?

  That's all you got. That's all you got. And the rest, we know it's there. And one of the questions was, how do we know? Right. How much it is? How would he get to this? You can measure how much gravity is out there because you can see the motions of objects. All right. And you can see how fast, for example, we are orbiting the center of the galaxy. You just do you just measure that. We can do that. No, of course, every day. But of course. And once you find out how fast we're going, you can say, well, how much material is between us and the center of the galaxy to enable us to go that speed? These are two very related numbers. The amount of gra- the amount of gravity pulling on you and how fast you're going in orbit. Okay. Those that they're connected in a single equation. You calculate it up.

• 4:27Neil deGrasse Tyson?

  You say, there should be this much gravity down there. And you count up all the stars and all the gas clouds, all the black holes, everything. And you cannot account for that much gravity. So there's too much gravity. There's it's a too much gravity problem. That's right. That's very cool. That's how we measure that. Now, the acceleration of the universe. We have supernovae. There's stars that blow up at the end of their lives and they're so bright, they outshine the entire galaxy in which they're embedded briefly, like for about a week. So that means galaxies really, really far away. If one of these supernova blow up, you say, hey, we just, we just saw you. All right. That was there 15 minutes? It was there. And so you have, and we know how bright the supernova should be, how luminous they should be at a given distance. Okay. All right.

• 5:12Neil deGrasse Tyson?

  So like 100 watt light bulb, put it a mile away. I know how dim that should look. Okay. A mile away, half a mile away, right in front of your face. You do this with supernovae. I know what bright, how, at whatever distance we find, I know what it should be. When you do that, what you find is that the, these distant galaxies are accelerating away from us. They're accelerating away. Oh, I get it. So because they're so, so, so that these are like our standard candles as you, that's an expression we, you don't hear much anymore, but it's, it's the metric that we use to know how far away an object is, is how dim the supernova is. Right. And so when we lay it all out on a graph, we find out that where it is versus how long it's been traveling. Mm hmm. Don't match up.

• 5:55Neil deGrasse Tyson?

  And so they had to have been accelerating to get there. And so you add all that, which we only know four, so we're dumb, stupid, ignorant about most of the universe, which is really cool. Keeps astrophysicists employed. And doing shows called StarTalk. StarTalk after hours.

• 6:10Speaker 01

  Wow.

• 6:10Neil deGrasse Tyson?

  That's a long answer, but it's a lot of the universe to get in there.

• 6:13Speaker 01

  Dude, that, you condensed it so well, that's an entire semester for some of us.

• 6:18Neil deGrasse Tyson?

  Yeah, actually, yeah, sure. Yeah, 96% of the universe put into three minutes.

• 6:22Speaker 01

  Wow, well done. Only our personal astrophysicist can do that. I have a sort of related question from Gene O'Donnell. Who discovered dark matter? And I know it wasn't Al Gore.

• 6:33Neil deGrasse Tyson?

  Ah.

• 6:35Speaker 01

  Sorry, Al.

• 6:36Neil deGrasse Tyson?

  Yeah, he discovered it on the internet.

• 6:37Speaker 01

  On, on the, on the, on the internet.

• 6:39Neil deGrasse Tyson?

  Yeah, so dark matter was discovered in the 1930s by a dude named Fritz Zwicky.

• 6:44Speaker 01

  Not Fritz.

• 6:45Neil deGrasse Tyson?

  That's totally Fritz.

• 6:46Speaker 01

  Aw, man. Look at that dude party. When did he have time to discover dark matter? That dude was always at a party.

• 6:52Neil deGrasse Tyson?

  So, he was, he was Swiss-born, American, I don't know if he was ever naturalized, but his whole professional career was in America. And he worked at Caltech in Pasadena, California, the California Institute of Technology. And he was measuring the movement of galaxies. Now, the example I just gave with, with the sun and our solar system orbiting the galaxy. He did that same measurement for galaxies orbiting one another in a cluster of galaxies. So, he's measuring how fast these galaxies are moving and says, "The speed they're moving tells me how much matter should be there."

• 7:28Speaker 01

  Right.

• 7:29Neil deGrasse Tyson?

  To account for the gravity. And he does the calculations and he's off by a factor of five or 10. Right. And he's double checks and triple checks his calculations, gets, they continually don't match. And he said, "There's missing matter somewhere." And it's, it was the beginning of the missing mass problem, today known as dark matter.

• 7:47Speaker 01

  I love it.

• 7:47Neil deGrasse Tyson?

  And there you have it, Fritz Zwicky. I think it was 1936.

• 7:51Speaker 01

  So, he's just covering a math error, is what we're saying.

• 7:53Neil deGrasse Tyson?

  Exactly.

• 7:54Speaker 01

  I can't find it.

• 7:55Neil deGrasse Tyson?

  More on that when we come back to StarTalk with the Cosmic Queries Edition.

• 8:17Neil deGrasse Tyson?

  We're back on StarTalk Cosmic Queries Edition and I got Leanne Lord with me. Hey Leanne.

• 8:24Speaker 01

  Hey, yeah, you know, we're early in on this, but already my head is starting.

• 8:27Neil deGrasse Tyson?

  Yes.

• 8:29Speaker 01

  I'm trying to wrap my mind around dark matter, dark energy, my man Fritz.

• 8:34Neil deGrasse Tyson?

  Fritz, we ended talking about Fritz.

• 8:36Speaker 01

  Mr. Zwicky, I'm sorry, let me be respectful, Mr. Zwicky.

• 8:38Neil deGrasse Tyson?

  It'd be Dr. Swicky.

• 8:40Speaker 01

  Um, Dr. Swicky, I'm sorry, sir.

• 8:42Neil deGrasse Tyson?

  Fritz Zwicky discovered dark matter back in, back then he was called Missing Mass. It was called the Missing Mass Problem.

• 8:49Speaker 01

  Okay.

• 8:49Neil deGrasse Tyson?

  And it's the longest unsolved problem in modern astrophysics.

• 8:53Speaker 01

  Oh, and not what women are thinking?

• 8:55Neil deGrasse Tyson?

  (laughing).

• 8:56Speaker 01

  Really? Okay.

• 8:58Neil deGrasse Tyson?

  No, that would be a longer problem.

• 8:59Speaker 01

  (laughing).

• 9:00Neil deGrasse Tyson?

  You know, a related, can I give a related comment to that, if I may?

• 9:03Speaker 01

  Um, it's your show, so yeah.

• 9:05Neil deGrasse Tyson?

  Okay, the study of the universe is the second oldest profession.

• 9:08Speaker 01

  (laughing) Seriously?

• 9:11Neil deGrasse Tyson?

  So, yeah, so the, both of these challenges go way back.

• 9:16Speaker 01

  Okay.

• 9:16Neil deGrasse Tyson?

  Uh, so, but, yeah, Fritz Zwicky was quite a colorful character and with a name like that, how could you not be?

• 9:22Speaker 01

  Yeah.

• 9:23Neil deGrasse Tyson?

  And he was cantankerous and he would scream at you and pound the table if you didn't agree, but he was brilliant and he was, he predicted the existence of pulsars, which are rapidly spinning balls of neutrons. And so we should call him Zwicky Stars, really, in his honor.

• 9:43Speaker 01

  I like it.

• 9:43Neil deGrasse Tyson?

  But they would, they would later be discovered and he had predicted them based on what he had just learned from the newly invented branch of physics called quantum mechanics. So that's Fritz Zwicky, cool dude.

• 9:54Speaker 01

  Wow, all this because he couldn't figure out women, he goes, forget it, I'm gonna figure out the galaxy.

• 9:58Neil deGrasse Tyson?

  Exactly, that's easier.

• 10:00Speaker 01

  It's easier.

• 10:02Neil deGrasse Tyson?

  All right, so what else you so so this is giving you a headache. Well, we'll try to lift that somehow.

• 10:06Speaker 01

  Yeah, no, no, no, it's it's, you know, I know when I am playing outside of my intellectual depth and I am not afraid to admit it.

• 10:13Neil deGrasse Tyson?

  We will make it part of your depth. So what

• 10:14Speaker 01

  That's why I come here.

• 10:15Neil deGrasse Tyson?

  Bring it on. So I haven't seen these questions. You got them off off our social media circles.

• 10:19Speaker 01

  Yes. Well, our next question is from Andrew Schaefer.

• 10:23Neil deGrasse Tyson?

  Mm hmm.

• 10:24Speaker 01

  And it's similar, but but different, I guess, of a kind. It's how how much dark matter or dark energy is predicted to be in the universe.

• 10:33Neil deGrasse Tyson?

  Hmm. Well, so the number that we put forth.

• 10:37Speaker 01

  Mm hmm.

• 10:37Neil deGrasse Tyson?

  Well, so let me back up. We measure the stuff. And so it turns out when we try to make galaxies, well, I mean, on a computer.

• 10:47Speaker 01

  I was about to say, did you just let me in on some top level stuff that I am not cleared to hear?

• 10:52Neil deGrasse Tyson?

  We have. Yeah, that's slipped out.

• 10:54Speaker 01

  There are men in dark suits coming in. Hello, gentlemen. What? I didn't hear anything. What?

• 10:59Neil deGrasse Tyson?

  Yeah, look at this light. So we are so the it turns out before we understood how deep the dark matter problem was, we had a hard time making galaxies on a computer. You put in matter, you spin it up, you see if it's self gravity because matter attracts itself. You watch the computer provided all your formulae are accurately captured in the program. Newton's laws of motion, differential equations that track where things move, and you put it all in there, you load it up, and we found out we can't make galaxies. Not only that, we can't make the structure of matter in the early universe unless we put dark matter in the equations.

• 11:42Speaker 01

  So something was missing.

• 11:43Neil deGrasse Tyson?

  Something was missing. And so not only does the universe show us it has dark matter, we need it in our formulations of the universe in order to create a universe that looks like the one that exists. So we have good theoretical confidence as well as observational requirement that dark matter is out there.

• 12:03Speaker 01

  And we we think that that missing thing is dark matter and not love.

• 12:08Speaker 01

  You need love to make a universe.

• 12:10Neil deGrasse Tyson?

  An absence of love. No, it's too much love. It's too much is more gravity than we can account for.

• 12:15Speaker 01

  Okay.

• 12:15Neil deGrasse Tyson?

  There it is.

• 12:16Speaker 01

  All right.

• 12:17Neil deGrasse Tyson?

  So what else you got?

• 12:18Speaker 01

  I have a question from Robbie Jaeger or Jaeger.

• 12:22Neil deGrasse Tyson?

  From where? From what source?

• 12:23Speaker 01

  Uh, Robbie does not identify, uh, where he or she is from. So it might be a, uh, a witness protection thing, but still has a quest for knowledge.

• 12:32Neil deGrasse Tyson?

  Uh huh.

• 12:32Speaker 01

  Uh, I have heard that dark matter and dark energy make up the majority of stuff in the universe. Uh, is the mass of all the black holes within galaxies figured into this calculation of stuff?

• 12:42Neil deGrasse Tyson?

  Oh, black holes are ordinary stuff.

• 12:45Speaker 01

  Oh.

• 12:46Neil deGrasse Tyson?

  I mean, yeah, they're exotic for our, in our lives.

• 12:49Speaker 01

  Right.

• 12:49Neil deGrasse Tyson?

  But for this four percent of the universe, we, we got all the black holes. I promise.

• 12:55Speaker 01

  Oh, so they're in there.

• 12:55Neil deGrasse Tyson?

  No, we totally.

• 12:56Speaker 01

  They're in the four percent of, of things that we get out of the apple pie slice of our understanding.

• 13:00Neil deGrasse Tyson?

  Yeah. So that's why dark matter is a, is really not a good term. We should just really call it Fred. Because, because, because.

• 13:08Speaker 01

  We're renaming dark matter Fred.

• 13:10Neil deGrasse Tyson?

  No, because we don't know that it's matter. All right. We, we just don't know. So to call it that already puts a bias in the expectation of what you would find. And that's not good science. So it's really just, we have no idea what it is. And call it something that doesn't make you think anything. So I just call it Fred. So.

• 13:29Speaker 01

  Okay. Fred. I'm, I'm, I would love to know who you think Ethel is, but alrighty then.

• 13:35Neil deGrasse Tyson?

  Well, that'd be dark energy. Fred, yeah, Fred and then you get Fred and Ethel. There you go.

• 13:39Speaker 01

  Well, you know what? This actually, I don't see the question here, but I, you know, I was looking.

• 13:42Neil deGrasse Tyson?

  You can ask too. You're allowed to ask.

• 13:43Speaker 01

  Well, yeah, no, that someone had asked that question. Apparently those were just placeholder names.

• 13:48Neil deGrasse Tyson?

  Yeah, they're placeholders. So that's why, um.

• 13:51Speaker 01

  So matter isn't correct.

• 13:53Neil deGrasse Tyson?

  And, and, and black holes are dark and they're matter. But it's, they're not dark matter. That's the thing. So that's why dark matter is really.

• 14:00Speaker 01

  They're dark and they're matter.

• 14:02Neil deGrasse Tyson?

  Yeah.

• 14:02Speaker 01

  But they're not dark matter.

• 14:03Neil deGrasse Tyson?

  And, and.

• 14:04Speaker 01

  This is you alleviating my headache?

• 14:05Neil deGrasse Tyson?

  Yes. Wait, wait. I can say more. They're dark. They're made of matter and they matter. But they're not dark matter.

• 14:13Speaker 01

  I thought you loved me, Neil.

• 14:14Neil deGrasse Tyson?

  You got that?

• 14:14Speaker 01

  I really.

• 14:15Neil deGrasse Tyson?

  Are we clear?

• 14:17Speaker 01

  Five more hours.

• 14:18Neil deGrasse Tyson?

  Just to clear the air. All right, what else you got?

• 14:22Speaker 01

  Okay, um, this is from Chris Butler.

• 14:24Neil deGrasse Tyson?

  Mm-hmm.

• 14:25Speaker 01

  And Chris says, when I first heard about dark matter or energy, I had the thought that it might be from the visible matter we know of being pulled into black holes and somehow was turned into dark matter or energy.

• 14:36Neil deGrasse Tyson?

  Hmm.

• 14:36Speaker 01

  Uh, cause all that matter has to go someplace, right?

• 14:38Neil deGrasse Tyson?

  Oh, yeah, yeah. Well, it'd be one thing if black holes ate their dinner and then spewed it out someplace else in the, in the universe or in the galaxy.

• 14:49Speaker 01

  So if black holes had a digestive tract?

• 14:50Neil deGrasse Tyson?

  A digestive tract, then you can think, well, maybe they're turning it into dark matter. Like, black holes are dark matter machines.

• 14:57Speaker 01

  Right.

• 14:58Neil deGrasse Tyson?

  But the, here's the thing, everything they eat remains contained within them. So you can see, as they eat, they have more and more of an effect on the passing of stars near them. And so the black holes have these huge sources of gravity contained within them. We understand that, we got that. That's not mysterious to us. Not only that, we've got a supermassive black hole in the center of our own galaxy, the Milky Way.

• 15:24Speaker 01

  Mm-hmm.

• 15:24Neil deGrasse Tyson?

  So, and other galaxies have like other supermassive black holes a billion times the mass of the sun. And you say, hey, have we accounted for that? Sure, go ahead and account for it. But the mass of the galaxy itself is like several hundred billion times the mass of the sun. So I add the one supermassive black hole and it's like several hundred billion and one. All right, so it's big as a solitary thing.

• 15:51Speaker 01

  Mm-hmm.

• 15:52Neil deGrasse Tyson?

  But in the scale of the, of the galaxy, it's just, it's, it's dust.

• 15:55Speaker 01

  Okay, it's big to us, but not big to the universe.

• 15:58Neil deGrasse Tyson?

  Not big to the galaxy.

• 15:59Speaker 01

  Galaxy.

• 15:59Neil deGrasse Tyson?

  Right, right, so even if we had neglected to count the black holes?

• 16:04Speaker 01

  All right, who forgot the black hole? Anybody? Did we not check this off? Do we have to start at one?

• 16:09Neil deGrasse Tyson?

  Exactly, even if you forgot them, everything we know about them and their frequency and the, and the likelihood in the galaxy, we got them all.

• 16:16Speaker 01

  Okay.

• 16:17Neil deGrasse Tyson?

  Yeah.

• 16:17Speaker 01

  Now, I, I, I do have a question based on something that you said.

• 16:20Neil deGrasse Tyson?

  Mm-hmm.

• 16:20Speaker 01

  That things enter a black hole, but they don't leave.

• 16:24Neil deGrasse Tyson?

  Yeah.

• 16:24Speaker 01

  So.

• 16:25Neil deGrasse Tyson?

  Not really. I mean, they they sort of leave, but not really.

• 16:28Speaker 01

  Okay, because I'm imagining that the black hole needs like a massive super colonic or something. That's because when she blows, it's gonna be awful. Stand back, everyone.

• 16:38Neil deGrasse Tyson?

  Yeah, colonic, I forgot that word. I'd never think I'd ever use that word in an astrophysics conversation.

• 16:44Speaker 01

  And that's why I'm here. This is what I bring.

• 16:47Neil deGrasse Tyson?

  That'd be a great new storefront, Black Hole Colonics, you know, that would. They would win in the colonics contest, I'm sure.

• 16:54Speaker 01

  See that in an episode of Doctor Who. I feel it coming on.

• 16:58Neil deGrasse Tyson?

  So black holes eat things, and as far as we know, they stay right there down in their center. But over time, the black hole slowly evaporates these particles. And Hawking first figured this out, and it's named in his honor. It's called Hawking Radiation. And given enough time, these particles inside the black hole will evaporate from just at the border of the event horizon. That's the place beyond which you don't return. But I throw in all your atoms, they come out one by one over time, very slowly. So it's an evaporation process, and it comes from quantum physics. It's a quantum physics phenomenon, actually. And I can, I don't have, I'm, okay, I can get it in the next 30 seconds because we're gonna have to go to break in a moment.

• 17:42Speaker 01

  Okay.

• 17:42Neil deGrasse Tyson?

  So I'll tell you Hawking Radiation in 30 seconds. Ready?

• 17:45Speaker 01

  Ready.

• 17:45Neil deGrasse Tyson?

  Okay, so you remember E equals mc squared?

• 17:47Speaker 01

  Of course.

• 17:48Neil deGrasse Tyson?

  E equals, E, energy is equivalent to matter, okay?

• 17:52Speaker 01

  Mm hmm.

• 17:53Neil deGrasse Tyson?

  So on the outer, outside edge of a black hole, the gravitational field is so strong, the gravitational energy is so intense, the gravitational energy becomes matter, right at the outer edge of the black hole, and that matter escapes. So the black hole evaporates because its gravitational energy is getting converted into matter. And you know something? Those particles that escape, invented out of the vacuum of space itself, have the same inventory of all the particles that went in in the first place.

• 18:25Speaker 01

  Ooh.

• 18:26Neil deGrasse Tyson?

  The black hole did not forget what it had eaten. You're listening to StarTalk Radio. We'll be back in a moment.

• 18:50Neil deGrasse Tyson?

  This is StarTalk Radio, the Cosmic Queries Edition, and I'm your host Neil deGrasse Tyson. I'm an astrophysicist at the American Museum of Natural History, and I host StarTalk. We've got Leanne Lord. Leanne?

• 19:04Speaker 01

  Yes.

• 19:04Neil deGrasse Tyson?

  Thanks for being on StarTalk.

• 19:06Speaker 01

  Well, thank you for having me back.

• 19:07Neil deGrasse Tyson?

  And I follow you on Twitter at LeanneLord.

• 19:09Speaker 01

  LeanneLord.

• 19:10Neil deGrasse Tyson?

  L-E-I-G-H-A-N-N. No one in the world spells it that way.

• 19:13Speaker 01

  No, they do not, yeah. My parents got real creative.

• 19:16Neil deGrasse Tyson?

  There you go. So you're reading these questions for me. I haven't seen them, and they're all on dark matter, dark energy.

• 19:21Speaker 01

  Yes, yes. I have to say, I'm very impressed with StarTalk listeners and fans. These are some very...

• 19:29Neil deGrasse Tyson?

  We've got awesome listeners.

• 19:30Speaker 01

  We have awesome listeners, man. These are some very learned and cogent folks.

• 19:35Neil deGrasse Tyson?

  Learned folk.

• 19:35Speaker 01

  And to that end, I have a question from William Flynn, and he wants to know, can you discuss how the experiment on the ISS may have uncovered hints of dark matter, and why it doesn't interact with ordinary matter?

• 19:49Neil deGrasse Tyson?

  Hmm.

• 19:50Speaker 01

  And why does that matter? That was me. That wasn't William.

• 19:54Neil deGrasse Tyson?

  And if you don't understand, what's the matter? Right. So, there was an experiment on the International Space Station.

• 19:59Speaker 01

  Yes.

• 20:00Neil deGrasse Tyson?

  He was using the abbreviated...

• 20:01Speaker 01

  The acronym, yes.

• 20:03Neil deGrasse Tyson?

  No, for an acronym, it has to be a pronounceable word.

• 20:05Speaker 01

  Oh, so it's not an acronym, it's then a...

• 20:08Neil deGrasse Tyson?

  An abbreviation.

• 20:09Speaker 01

  An abbreviation.

• 20:10Neil deGrasse Tyson?

  Yeah.

• 20:11Speaker 01

  We are so full-service here on what you can learn at StarTalk.

• 20:14Neil deGrasse Tyson?

  So NASA is an acronym, SCUBA is an acronym, laser is an acronym.

• 20:18Speaker 01

  Laser's an acronym?

• 20:19Neil deGrasse Tyson?

  Oh, yeah.

• 20:20Speaker 01

  What's it an acronym for?

• 20:21Neil deGrasse Tyson?

  The Light Amplification by the Stimulated Emission of Radiation.

• 20:26Speaker 01

  That sounds really dirty.

• 20:27Neil deGrasse Tyson?

  (laughing)

• 20:29Speaker 01

  Can you say that? Is the FCC listening? Please don't fine me for that.

• 20:33Neil deGrasse Tyson?

  The Light Amplification by the Stimulated Emission of Radiation.

• 20:36Speaker 01

  And he's saying it again!

• 20:37Neil deGrasse Tyson?

  That's right. So that's, so that's laser. So those are acronyms.

• 20:42Speaker 01

  Okay.

• 20:42Neil deGrasse Tyson?

  Yeah, nim, like pseudonym, nim is name, I guess, in Latin or something. So, um, yeah, so, so, uh, now I, I forgot what the question was.

• 20:53Speaker 01

  Wow. Well, we're gonna learn something else. No, no, no. Can we, you can discuss how the experiments is, uh...

• 20:58Neil deGrasse Tyson?

  On the ISS.

• 20:59Speaker 01

  Yes.

• 20:59Neil deGrasse Tyson?

  Not an acronym, International Space Station. So, uh, International Space Station, as you know, orbits outside of Earth's atmosphere. So there's certain particles that come from space that don't make it to Earth's surface. So if you want to study them, there are a lot of things that don't make it to Earth's surface.

• 21:13Speaker 01

  Intelligence, what?

• 21:14Neil deGrasse Tyson?

  Ultra, most ultraviolet light hitting the Earth, hitting Earth's zone does not make it through the atmosphere. So when people get a tan, or get burned, or darken from the ultraviolet light from the sun, that is a tiny fraction of the ultraviolet light that's actually hitting Earth. Most of that get absorbed, gets absorbed up there in the ozone layer, which is why we need the ozone. But that's a whole other show. So the International Space Station is above the atmosphere. So we can see things, detect things that never reaches Earth's surface. Among them are very high energy particles flying from the center of the galaxy, and they're called cosmic rays.

• 21:49Speaker 01

  Okay.

• 21:49Neil deGrasse Tyson?

  They have very high energy, higher energy than any particle accelerator we have ever created here on Earth. Nature is the biggest atom smasher there ever was.

• 22:00Speaker 01

  Nature smash, Hulk smash. I'm sorry.

• 22:05Neil deGrasse Tyson?

  So...

• 22:07Speaker 01

  I just got fired.

• 22:08Neil deGrasse Tyson?

  So there's, I, I, I think it's the, if I remember correctly, there's an Alpha Proton X-ray Spectrometer onboard the International Space, you're shaking your head like a cartoon character.

• 22:17Speaker 01

  I was just taking it in. I just got hit with a, oh, the particle there.

• 22:20Neil deGrasse Tyson?

  It sounds like something off of Batman's utility belt.

• 22:22Speaker 01

  It does.

• 22:22Neil deGrasse Tyson?

  No, not the Alpha Proton X-ray Spectrometer, Batman! Right, so it's a, it's a device that can measure the energy of high-speed, high-energetic particles, basically.

• 22:32Speaker 01

  Also, we can, we can't make it, but we can measure it.

• 22:35Neil deGrasse Tyson?

  No, we, yeah, exactly, yeah. We can't make these particles. We are, so accelerators aren't powerful enough.

• 22:40Speaker 01

  Okay.

• 22:40Neil deGrasse Tyson?

  Now, there is a hypothesis that dark matter actually is matter. But a matter that exists only in very high energies, in high regimes of energy. And it's a whole other set of particles that are perfectly fine existing, but don't interact with our particles.

• 23:02Neil deGrasse Tyson?

  Parallel particles, if you will.

• 23:05Speaker 01

  I was gonna say racist, but yeah, whatever.

• 23:07Neil deGrasse Tyson?

  And so, the existence of these particles has been suggested as the point of origin of dark matter. And so, you wouldn't see them because they don't interact with our light. They don't give off light that we can know of or can measure. They would have gravity.

• 23:23Speaker 01

  Okay.

• 23:23Neil deGrasse Tyson?

  They would sort of permeate the cosmos through these, you know, uh, through these mechanisms. And so, there, that would be a, a, in a hypothesis. And there was a detection made just recently, which is why the question was asked, for sure. Someone was also on top of current events. That hinted that a dark matter particle was discovered on that detector on the International Space Station above Earth's atmosphere.

• 23:49Speaker 01

  So money well spent.

• 23:50Neil deGrasse Tyson?

  Uh, that's $3 billion a year. I mean, what's, what's the universe worth to you?

• 23:56Speaker 01

  I, I wasn't prepared to answer any questions today. Um, can I get a coupon? Because I don't think I can afford the entire universe.

• 24:03Neil deGrasse Tyson?

  I was gonna say a rain check. I'll give you a space check for that. You come back later with a response.

• 24:07Speaker 01

  Yeah.

• 24:08Neil deGrasse Tyson?

  So what else you got?

• 24:10Speaker 01

  Uh, we'll do a quick question. Um, with the newfound evidence of dark matter, does it change the field of astrophysics in any way? Oh, yeah, well, yeah, that's an easy question. I'm sorry.

• 24:17Neil deGrasse Tyson?

  If the new dark, if this new particle is the source of dark matter, then dark matter is matter. All right, as I was saying earlier in the show.

• 24:25Speaker 01

  Earlier, because it might not be.

• 24:25Neil deGrasse Tyson?

  It might not be, it might be something, we just have no idea what it is. It could be like regular matter, regular gravity from another universe leaking into our universe. I mean, who knows? Right, so if it is, that tightens up our, the, the, the wild ideas.

• 24:40Speaker 01

  Right, right.

• 24:40Neil deGrasse Tyson?

  About what it could be. So, it wouldn't change how we conduct business, but it constrains how science fiction-y you can get by trying to account for it.

• 24:49Speaker 01

  Ooh, okay.

• 24:50Neil deGrasse Tyson?

  Yeah, there you go. And you're a science fiction buff, right?

• 24:52Speaker 01

  Just a little bit.

• 24:53Neil deGrasse Tyson?

  Oh, and apparently you're a Whovian as well.

• 24:56Speaker 01

  Yes.

• 24:56Neil deGrasse Tyson?

  Referencing Doctor Who moments ago. Uh, when we come back, more of StarTalk Cosmic Queries Edition. I'm here with Lee and Lord. See you in a moment.

• 25:23Neil deGrasse Tyson?

  This is StarTalk. I like to think of it as the after-hours edition. But it's StarTalk Cosmic Queries.

• 25:32Speaker 01

  After dark.

• 25:33Neil deGrasse Tyson?

  After dark. No, because the universe is dark.

• 25:37Speaker 01

  Yes.

• 25:37Neil deGrasse Tyson?

  So, the universe in the dark. So, yeah, because day and night is just as an Earth thing, you know?

• 25:46Speaker 01

  Oh, is it really? That's so Earth.

• 25:48Neil deGrasse Tyson?

  Waste my time. So Earth. So, we solicited questions from our readers and fans and everybody to ask about dark matter and dark energy, which has been in the news lately, and you've been asking them. So, fire away.

• 26:01Speaker 01

  Yes. These questions are from Facebook. These folks are really stepping in with some great questions. And I love this one. This next one is my favorite. It's from Anthony Delemme, if I'm pronouncing that correctly. And very specifically, it's from Mr. Delemme's period five, 8th grade science class at Cedar Middle School in Hesperia, California. So, we know exactly where you are, kids. Now, the question is, would it be possible to capture and contain an amount of dark matter and be able to study it in its purest form?

• 26:34Neil deGrasse Tyson?

  So, these are middle schoolers?

• 26:35Speaker 01

  These are middle schoolers.

• 26:36Neil deGrasse Tyson?

  Okay, so the hormones-

• 26:37Speaker 01

  My faith is restored.

• 26:38Neil deGrasse Tyson?

  Hormones haven't kicked in yet, apparently.

• 26:39Speaker 01

  Or we were in a lucid moment in between harmonic fluctuations.

• 26:45Neil deGrasse Tyson?

  So, that's a great question, because scientifically, to study anything, you want to bring it in the lab and poke it and turn it and twist it and heat it and cool it.

• 26:57Speaker 01

  Are we talking about science or dating? Because I'm a little confused now.

• 27:00Neil deGrasse Tyson?

  Now, to the astrophysicist, in that sense, we are the humblest of all sciences, because we do not control or manipulate our subjects. We cannot take the black hole we view and bring it into the lab and kill it, poke it-

• 27:16Speaker 01

  Because it'll eat you.

• 27:17Neil deGrasse Tyson?

  Cut it open. So, it is the gentlest, humblest of all disciplines.

• 27:24Speaker 01

  Wow. Humble and talking about itself. That's great.

• 27:29Neil deGrasse Tyson?

  So, uh, one of the other challenges with dark matter is you can't contain it. You know why you can't contain it? It doesn't interact with our matter. And the non-interaction part means you can't put it in a box because the thing doesn't even see your box. If it saw your box, the box might contain it. Dark matter permeates all space and all matter.

• 27:55Speaker 01

  Okay.

• 27:56Neil deGrasse Tyson?

  Without you knowing it. But we measure its gravity, alright? We know that its gravity is there. So what we might need is some kind of a gravitational bottle. I wouldn't know how to make one.

• 28:06Speaker 01

  Okay.

• 28:07Neil deGrasse Tyson?

  But the same challenge arises with very high-temperature plasma. Not blood plasma, this physics, astrophysical plasma, very hot gas. The sun is a ball of plasma.

• 28:17Speaker 01

  Right.

• 28:17Neil deGrasse Tyson?

  Alright? Aurora, the northern lights, that's plasma.

• 28:21Speaker 01

  Okay.

• 28:22Neil deGrasse Tyson?

  Alright? Plasma is like a lot of the universe, very, you don't often see it walking down the street. But plasma is everywhere in the universe. Plasma is so hot. The plasma like in the center of the sun is so hot. How do you carry that around? It vaporizes any container you put it in. So you need a special container, and the best way we know of is a magnetic bottle.

• 28:42Speaker 01

  Okay.

• 28:43Neil deGrasse Tyson?

  You create a magnetic field in the shape of a bottle, put the plasma in it, so it's not touching any matter. Otherwise, it would have vaporized the matter. It's touching a field.

• 28:51Speaker 01

  Hmm.

• 28:51Neil deGrasse Tyson?

  So with dark matter, we would need like a dark ma- we would need something made of dark matter on one side and made of regular matter on the other in the lining or something.

• 29:02Speaker 01

  Okay.

• 29:03Neil deGrasse Tyson?

  So that it doesn't pen- penetrate that membrane. So you can carry the thing around and bring it into the lab. But you know what the biggest problem? Dark matter doesn't even interact with itself.

• 29:14Speaker 01

  Wow.

• 29:15Neil deGrasse Tyson?

  So.

• 29:16Speaker 01

  We need a therapist in here. What's the matter, dark matter? Why aren't you talking to yourself? What's going on there?

• 29:21Neil deGrasse Tyson?

  So with regular matter, we know we interact with ourselves.

• 29:24Speaker 01

  Mm-hmm.

• 29:24Neil deGrasse Tyson?

  Because we can collapse and make solid objects. What is a solid object but a collection of atoms that got to know one another and are stuck to each other?

• 29:34Speaker 01

  Like marriage.

• 29:35Neil deGrasse Tyson?

  So, so we, in the 4% of the universe that is matter, can actually create solid objects.

• 29:41Speaker 01

  Okay.

• 29:42Neil deGrasse Tyson?

  As far as we know, dark matter cannot.

• 29:44Speaker 01

  Create solid objects?

• 29:45Neil deGrasse Tyson?

  Yeah, because it can't interact with itself and stay stuck to itself. So that makes containing it and studying it in all the traditional ways a challenge.

• 29:53Speaker 01

  Okay, wow. So Schrodinger's cat, not dark matter?

• 29:56Neil deGrasse Tyson?

  Not dark matter. So we've got like a half a minute. What else you got? Well, I like answering questions in soundbite mode.

• 30:03Speaker 01

  I love it. Okay. Is it well from Robert Atalo? Is dark matter convertible to dark energy as a regular matter is convertible to regular energy?

• 30:12Neil deGrasse Tyson?

  Uh, no, they're complete. As far as we know, as far as we know, they have nothing to do with one another. Maybe.

• 30:19Speaker 01

  Is this where the naming thing becomes a problem?

• 30:22Neil deGrasse Tyson?

  Well, here's the thing. In principle, if energy can become anything, all right, E equals mc squared.

• 30:28Speaker 01

  Yeah, he says it here.

• 30:28Neil deGrasse Tyson?

  We got that. If energy can, maybe I can take our energy, take our matter, convert it into energy, and then turn that energy into dark matter. I think in principle you could do that, but I don't know how.

• 30:40Speaker 01

  Okay, that's honest.

• 30:42Neil deGrasse Tyson?

  Yeah. So when we come back, we will enter the last segment of Cosmic Queries, and it is the lightning round.

• 30:50Speaker 01

  Uh oh.

• 30:51Neil deGrasse Tyson?

  Be there.

• 31:10Neil deGrasse Tyson?

  We're back at StarTalk After Hours. StarTalk, the Cosmic Queries edition. This is the final segment of the hour.

• 31:18Speaker 01

  Yes.

• 31:18Neil deGrasse Tyson?

  And it's the lightning round.

• 31:21Speaker 01

  Dun dun dun.

• 31:21Neil deGrasse Tyson?

  Because we get so many questions. I gotta, we gotta do one where I give you soundbite answers.

• 31:25Speaker 01

  Yes.

• 31:26Neil deGrasse Tyson?

  All right. So let's do this.

• 31:27Speaker 01

  All right.

• 31:28Neil deGrasse Tyson?

  Leanne Lord.

• 31:29Speaker 01

  Now, this question, and we're gonna do this fast, is from Patrick Seidelik, and he says, how did dark matter come into being after the Big Bang?

• 31:36Neil deGrasse Tyson?

  We have no idea. Next.

• 31:38Speaker 01

  Wow, Joey Sellers, is dark matter energy increasing?

• 31:41Neil deGrasse Tyson?

  Wait, wait, wait. But we know that dark matter was there from the beginning.

• 31:44Speaker 01

  Okay.

• 31:45Neil deGrasse Tyson?

  We know it's been there from the beginning, but we have no idea how and why it came into being.

• 31:50Speaker 01

  So we have to unring the bell because you're unlightening that question.

• 31:54Neil deGrasse Tyson?

  There you go.

• 31:55Speaker 01

  Joey Sellers wants to know, is dark matter energy increasing as the universe expands?

• 31:59Neil deGrasse Tyson?

  No, dark matter is, as far as we know, the same in its proportion as a fraction of the total gravity in the universe. That's the same, and gravity's staying the same, so we're fine.

• 32:11Speaker 01

  Okay, Casey Wheeler Becker wants to know, how does dark matter influence time?

• 32:15Neil deGrasse Tyson?

  Ooh, dark matter, like anything else in the universe that contains energy, Einstein's special theory of relativity says that time slows down in the presence of high sources of gravity. And so, if you have a region where there's a lot of dark matter, if you can find a place near that dark matter that is high gravity from that dark matter, your time will tick more slowly. Your metabolism will metabolize less quickly.

• 32:47Speaker 01

  Not going there.

• 32:48Neil deGrasse Tyson?

  Next.

• 32:49Speaker 01

  Larry Bellomo wants to know if dark matter does not interact electromagnetically with ordinary matter, how does it exert its influence on the atoms and particles that make us?

• 32:57Neil deGrasse Tyson?

  It does not influence any light. You cannot see it because it doesn't either absorb, reflect, refract, disperse light. So that's as dark as you can get. The light does not even know it's there. But what light does is not the same thing as gravity. It's got gravity. We can talk about gravity without talking about light. And it's got gravity and we feel it.

• 33:24Speaker 01

  All right, what would happen if all the dark matter in the universe suddenly vanished?

• 33:29Neil deGrasse Tyson?

  Awesome question. If all the dark matter vanished, our galaxy would fly apart. Because all the speeds of the orbits that all the solar systems have is the right speed for the regular matter plus the dark matter's gravity to contain it. If you instantly take away the dark matter, we fly away and all the orbits go cockamamie and galaxy clusters fly apart and everything goes haywire.

• 33:53Speaker 01

  Wow, I'm actually starting to get this. Okay, Robert Atala wants to know if the Higgs boson gives mass to regular matter, does it also give mass to dark matter?

• 34:02Neil deGrasse Tyson?

  Ooh.

• 34:03Speaker 01

  Go, Robert.

• 34:04Neil deGrasse Tyson?

  First, I don't know the answer to that question, but I would guess that particles, if the Higgs boson, which interacts with our matter, could interact with dark matter, then we'd be interacting with dark matter.

• 34:17Speaker 01

  Ah.

• 34:17Neil deGrasse Tyson?

  Okay, right? So, the Higgs boson, I'm judging this. I mean, I got people I can call on this, but

• 34:24Speaker 01

  We got people.

• 34:26Neil deGrasse Tyson?

  I got people. So, the Higgs boson is talking to us and our kind of matter, not the dark matter.

• 34:32Speaker 01

  Okay.

• 34:33Neil deGrasse Tyson?

  By the way.

• 34:34Speaker 01

  Unring, unring.

• 34:36Neil deGrasse Tyson?

  Dark matter might have its own Higgs boson.

• 34:38Speaker 01

  Oh, see now.

• 34:39Neil deGrasse Tyson?

  Giving mass to it. And wouldn't that be cool at the Higgs boson bar? You know, where all the Higgs bosons hang out.

• 34:46Speaker 01

  That's what they're talking about.

• 34:47Neil deGrasse Tyson?

  You got it. Next.

• 34:48Speaker 01

  Jesse Turner wants to know, could dark matter and gravity be anything like the north and south poles of magnetism, like the opposite forces in the universe?

• 34:54Neil deGrasse Tyson?

  Ooh, he's into like the good and evil and the up and down and the front and back. Uh, it's unlikely, only because there's six times as much dark matter as there is regular matter. Rather, there's six times more gravity about which we know nothing than there is gravity about which we think we know everything. And so unlike magnetic poles where they're equal and opposite, these may, these may be opposite, but they're certainly not equal.

• 35:19Speaker 01

  All right.

• 35:20Neil deGrasse Tyson?

  All right.

• 35:21Speaker 01

  Oliver Gebberdinger, or Gebberding, uh, how much can we learn about dark matter with gravitational wave detectors like LIGO and LISA?

• 35:28Neil deGrasse Tyson?

  Ooh, nothing. Well, no.

• 35:31Speaker 01

  All right, next question.

• 35:32Neil deGrasse Tyson?

  No, the problem is, the gravitational wave detectors, LIGO, the Laser Interferometric Gravitational Observatory, that would be a what?

• 35:40Speaker 01

  That's an acronym. An acronym!

• 35:42Neil deGrasse Tyson?

  See, I can learn some stuff. Yeah, you got, okay. So, LIGO is a great, uh, uh, big physics, physics experiment that is looking for ripples in the fabric of spacetime caused by disturbances in the

• 35:56Speaker 01

  The force?

• 35:57Neil deGrasse Tyson?

  Distribution of matter in the universe. Matter can get collapsed densely enough to create a ripple. If you're spread out, like dark matter is, you're not making ripples.

• 36:07Speaker 01

  Okay.

• 36:08Neil deGrasse Tyson?

  All right, so, everything I know about LIGO tells me that it's gonna measure our matter, not theirs.

• 36:13Speaker 01

  Got it.

• 36:14Neil deGrasse Tyson?

  All right.

• 36:15Speaker 01

  Richard Smith from Frisco, Texas, love it. In what ways might dark matter affect the rotation of galaxies?

• 36:21Neil deGrasse Tyson?

  Oh, well, okay, we hinted that earlier in the show. Dark matter enables galaxies to rotate as fast as they do.

• 36:27Speaker 01

  Okay.

• 36:28Neil deGrasse Tyson?

  Pure and simple. And the mismatch between what pulls the gra, the, what pulls on the stars and the speed the stars are going, that was discovered in 1976 by Vera Rubin. She's still alive, uh, a, a senior astronomer, an astrophysicist in my community. Cool chick. She discovered that in 1976. That galaxies needed dark matter as well. I think, give me one more, and we gotta call it.

• 36:51Speaker 01

  Brandon Neal, if dark matter has a gravitational pull and we don't see it, could it hinder space travel outside our solar system?

• 36:56Neil deGrasse Tyson?

  Uh, no, because it's so thinly spread across the galaxy. It's all around you. No, it's not in the way. Leanne, we gotta wrap this up. Thanks for being on StarTalk Radio, and I'm on your list at veryfunnylady.com. Get to know where you perform as you travel the countryside. Uh, this has been brought to you in part by a grant from the National Science Foundation. I'm Neil deGrasse Tyson, your personal astrophysicist, bidding you, as always, to keep looking up.