Cosmic Queries – Galaxies Galore

What does JWST tell us about galaxy formation? Neil deGrasse Tyson and Chuck Nice answer questions about galaxies, measuring the distance of far away objects, dark matter, primordial galaxies, and more!

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

• 0:00Neil deGrasse Tyson?

  Coming up on StarTalk, Cosmic Queries, Galaxies galore. You're gonna learn about how we get the distances to things in the universe. And what else is going on with the James Webb Space Telescope messing with our tidy theories of the early universe. All that and more, coming up on StarTalk.

• 0:20Neil deGrasse Tyson?

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

• 0:33Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. Co-host Chuck Nice. Chuck, all right, man, how you doing?

• 0:40Chuck Nice?

  I'm doing great. How's it going, Neil?

• 0:43Neil deGrasse Tyson?

  Yeah, we're a little overdue for another Cosmic Queries.

• 0:45Chuck Nice?

  Yes.

• 0:46Neil deGrasse Tyson?

  Which is always a fan favorite. And apparently today has a topic.

• 0:50Chuck Nice?

  Oh.

• 0:51Neil deGrasse Tyson?

  Because we've been doing a lot of Galactic Gumbo lately.

• 0:54Chuck Nice?

  Yeah, yeah.

• 0:54Neil deGrasse Tyson?

  But this one is.

• 0:55Chuck Nice?

  Galacti.

• 0:59Neil deGrasse Tyson?

  Just grab bag of, of, of, but this one is galaxies galore.

• 1:03Chuck Nice?

  Oh.

• 1:04Neil deGrasse Tyson?

  So maybe, are they all about galaxies? Is that what you put them together?

• 1:07Chuck Nice?

  Must be.

• 1:08Neil deGrasse Tyson?

  Galaxies are my thing, you know?

• 1:09Chuck Nice?

  Well.

• 1:10Neil deGrasse Tyson?

  Me and galaxies go way back.

• 1:11Chuck Nice?

  Let's hope so.

• 1:14Neil deGrasse Tyson?

  Well, I'm on the wrong show.

• 1:15Chuck Nice?

  Yeah, we're, we're in a lot of trouble. It was just like, I don't know what we're gonna do now that they're asking about galaxies.

• 1:23Chuck Nice?

  I don't know any, I don't, you know.

• 1:25Neil deGrasse Tyson?

  All right, so bring it on.

• 1:26Chuck Nice?

  Okay, let's get to it. Let's get right to it. Uh, we got Bruce Ryan, who says, greetings, gents.

• 1:34Neil deGrasse Tyson?

  Who changed his name so that you could pronounce it? Just thought I would tell you that.

• 1:37Chuck Nice?

  Yes, I'm sure. And by the way, thank you, Bruce. Yes. Actually, I should thank your parents. You know, that's you.

• 1:46Chuck Nice?

  Uh, he says, greetings, gents. I'd love to know how you determine how far away stars or even galaxies are from Earth? And isn't that distance based on the light we're seeing now? As opposed to the actual distance, given the expansion of the universe? Thanks in advance, Bruce Ryan.

• 2:05Neil deGrasse Tyson?

  All right.

• 2:06Chuck Nice?

  Well, look at that.

• 2:07Neil deGrasse Tyson?

  So, so I, there are two ways I can answer that. One is completely lazy. All right?

• 2:12Chuck Nice?

  All right.

• 2:13Neil deGrasse Tyson?

  All right, so I'll give that answer second.

• 2:15Chuck Nice?

  No, give the lazy answer first.

• 2:16Neil deGrasse Tyson?

  Really?

• 2:18Chuck Nice?

  I mean, unless it's just, unless it's like, yes. Like, if it's that lazy, then.

• 2:24Neil deGrasse Tyson?

  No, no, no, the lazy answer is.

• 2:25Chuck Nice?

  Go ahead.

• 2:26Neil deGrasse Tyson?

  Our second StarTalk book, published with National Geographic, called Cosmic Queries, has an entire section on how astronomers find distances to things in the universe.

• 2:42Chuck Nice?

  Ooh.

• 2:43Neil deGrasse Tyson?

  And it was called The Distance Ladder. It's called The Distance Ladder because you figure out the distance to nearby things.

• 2:52Chuck Nice?

  Right.

• 2:53Neil deGrasse Tyson?

  And then you step on that rung, and that enables you to then think about distances to the next categories of objects, because the same methods don't apply at all distances.

• 3:03Chuck Nice?

  Right.

• 3:03Neil deGrasse Tyson?

  So, the, the objects that are farther away depend on the accuracy of methods and tools you use for, for closer objects, right on down to the distances to nearby stars and even the planets themselves.

• 3:19Chuck Nice?

  Right, I was gonna say, does that apply to the planets?

• 3:21Neil deGrasse Tyson?

  Right, so, so my answer to you is, read the damn book.

• 3:25Chuck Nice?

  That's the lazy answer, read the book.

• 3:28Neil deGrasse Tyson?

  Yeah, that, if you get, nice big fat book, makes a good gift, makes a good gift, but there's an entire, a lot of energy was put, many, many pages on this, so, just so you know. And, yes, by the time we get to galaxies, their light has been traveling for a great, uh, time before it reaches us, but we have other evidence to show that the speed of light has been constant, not only across space, but also through the depths of time. Otherwise, we would be, we would not be getting the right answers to things that are far away, which depend on the light travel time and things like this, and how fast they're moving in the expanding universe. There's a lot of interdependent factors there.

• 4:11Chuck Nice?

  Right.

• 4:12Neil deGrasse Tyson?

  So that's the, that's the, that's the easy answer. But I'll give you just a, uh, I'll, I'll, I'll give you a starter answer to get you ready for when you get the book.

• 4:22Chuck Nice?

  When you get the book, okay.

• 4:23Neil deGrasse Tyson?

  Okay, so here it is. So, um.

• 4:28Neil deGrasse Tyson?

  Okay, we have two eyes. And if you put your two fingers out in front of you, you can have them hit each other every time, okay?

• 4:36Chuck Nice?

  Mm-hmm.

• 4:37Neil deGrasse Tyson?

  You're using a stereoscopic vision to make that happen. If you try that with one eye, okay? Try, put your arm, your fingers at arms distance, and use two eyes and have them connect to each other, okay?

• 4:50Chuck Nice?

  Boom, boom, boom.

• 4:50Neil deGrasse Tyson?

  Just do that. Can you do that?

• 4:52Chuck Nice?

  Easy.

• 4:53Neil deGrasse Tyson?

  Now, now bring your hands back in.

• 4:55Chuck Nice?

  Okay.

• 4:55Neil deGrasse Tyson?

  Close one eye.

• 4:56Chuck Nice?

  Okay.

• 4:57Neil deGrasse Tyson?

  Put your arms out, now try it again.

• 4:59Chuck Nice?

  Okay. Oh, my gosh.

• 5:01Neil deGrasse Tyson?

  Whoa.

• 5:03Chuck Nice?

  All right, first of all, uh, officer, I do not think that this is a fair test. I'm just saying, uh, you know, I have one beer at work and quite frankly, I... Wow, that is, that's amazing.

• 5:20Neil deGrasse Tyson?

  Yeah, yeah. So, so let the record show that Chuck could not have his fingers, neither could I. I do, I close one eye, put my hands back, and I miss it by an inch.

• 5:28Chuck Nice?

  Yeah, yeah, it's so funny.

• 5:30Neil deGrasse Tyson?

  Or centimeter.

• 5:30Chuck Nice?

  Yeah.

• 5:31Neil deGrasse Tyson?

  Yeah, so, but you have to like, you know, refresh the...

• 5:35Chuck Nice?

  Right, right, yeah. You can't leave it, because if you just leave it there, your brain actually makes up the difference and does it for you.

• 5:43Neil deGrasse Tyson?

  Because you know what you're trying to do.

• 5:44Chuck Nice?

  You know what you're trying to do.

• 5:46Neil deGrasse Tyson?

  Right, so with two eyes, you do it.

• 5:47Chuck Nice?

  Right.

• 5:48Neil deGrasse Tyson?

  Okay? You do it every time.

• 5:49Chuck Nice?

  Boom, boom, boom.

• 5:50Neil deGrasse Tyson?

  Bring your hands back in, go one eye, do it, and you miss.

• 5:53Chuck Nice?

  Look at that.

• 5:54Neil deGrasse Tyson?

  So, so that's called, so what we did was, it's a, it's a method of triangulation. You have two angles of view. So in other words, you have one sightline that intersects, it could be anywhere along the sightline.

• 6:08Chuck Nice?

  Right.

• 6:08Neil deGrasse Tyson?

  If you have two sightlines.

• 6:10Chuck Nice?

  Right.

• 6:11Neil deGrasse Tyson?

  Those two sightlines intersect at a single point.

• 6:13Chuck Nice?

  Right.

• 6:14Neil deGrasse Tyson?

  And geometrically, you can know exactly the distance to that object using this method. So, we, my people are very clever. Very clever. We said, let's do that with the Earth's orbit.

• 6:28Chuck Nice?

  Right, right.

• 6:30Neil deGrasse Tyson?

  The Earth's orbit, okay? Because, consider, the farther away something is, the less useful this separation of your eyes will be.

• 6:39Chuck Nice?

  Right.

• 6:40Neil deGrasse Tyson?

  Okay, think about it, right? If something is a mile away, you can't use star vision to get a distance to it. It's just far, alright? Stars are far. So, how do you help out? The baseline of what would be your eye sockets? For something that's that far away, you use the entire orbit.

• 7:00Chuck Nice?

  Orbit of the Earth around, oh wow.

• 7:03Neil deGrasse Tyson?

  And that's something? So like one eye? It is. One eye is Earth in June.

• 7:10Chuck Nice?

  Right.

• 7:10Neil deGrasse Tyson?

  The other eye is Earth in December.

• 7:12Chuck Nice?

  Right, so because they're in two different spots, it's your left eye and your right eye. And then you have a sightline, and then you look for the points where they come together.

• 7:21Neil deGrasse Tyson?

  Sightlines, okay?

• 7:22Chuck Nice?

  Wow.

• 7:23Neil deGrasse Tyson?

  And so, so here the way this works is.

• 7:25Chuck Nice?

  My god, that is so simple and so smart.

• 7:28Neil deGrasse Tyson?

  My people, these are my people. These are my people, okay? Proud of my people.

• 7:34Chuck Nice?

  Yeah.

• 7:35Neil deGrasse Tyson?

  So, they, so you get the nearby stars. And it turns out they're far, but they're close enough for this method to work. And here's what you do. You take a picture of that star against the background stars, okay?

• 7:51Chuck Nice?

  Okay.

• 7:51Neil deGrasse Tyson?

  And it's gonna be sitting in front of some pattern. Then you wait six months, you take that same picture again. And your sightline on that star has changed. And now it's sitting slightly in front of a different pattern of stars. Very slightly. That corresponds to an angle. And that angle, okay? Is one part of that triangle. And we have the base of that triangle, which is the diameter of Earth's orbit.

• 8:22Chuck Nice?

  Mm-hmm.

• 8:23Neil deGrasse Tyson?

  Right? Because it's not the radius, it's the full diameter, that's like the diameter between your two eyes. You do the geometry of this bottom, we know the distance from Earth to the sun. You need that because that's one of the legs of this triangle. Before we knew the distance from Earth to the sun, you could not successfully apply this method. Because you'd be missing one of the dimensions. Let's say you had the wrong measurement here. That wrong measurement would eke its way into these other measurements.

• 8:54Chuck Nice?

  Right.

• 8:54Neil deGrasse Tyson?

  And propagate through all of your estimates for the distances to stars in your neighborhood.

• 9:00Chuck Nice?

  So before we knew the sun was 93 million miles away, the answer to this question was, "Whoa, you don't even wanna know."

• 9:11Neil deGrasse Tyson?

  I never thought of giving that answer to a question.

• 9:14Chuck Nice?

  How far is the next star after the sun?

• 9:18Chuck Nice?

  You don't even wanna know. You don't even wanna know. That's far.

• 9:22Neil deGrasse Tyson?

  So that's why it's a ladder. Because any error at the base level of this would propagate to all other levels. Okay? So now we get the distance to the nearby stars. Okay?

• 9:33Chuck Nice?

  Right.

• 9:34Neil deGrasse Tyson?

  Now, we hope, well, we made sure one of those stars is like the sun. Okay?

• 9:39Chuck Nice?

  Right.

• 9:39Neil deGrasse Tyson?

  Now, we know the luminosity of the sun. We're orbiting the damn thing. And luminosity is how much energy it's giving off. So

• 9:50Neil deGrasse Tyson?

  if I know how much energy it's giving off, then I start putting it farther and farther away from me, it gets dimmer, doesn't it?

• 9:57Chuck Nice?

  Of course, yeah.

• 9:58Neil deGrasse Tyson?

  If I know what its intrinsic luminosity is, then I can calculate the rate at which it gets dimmer as it moves away from me. It's called the inverse square law of light.

• 10:11Chuck Nice?

  Okay.

• 10:12Neil deGrasse Tyson?

  So if I find another star like the sun, I get spectroscopically, I get to say, "That star is just like the sun."

• 10:19Chuck Nice?

  Just like our sun, right.

• 10:21Neil deGrasse Tyson?

  And therefore, I believe I know its luminosity because I know the sun's luminosity.

• 10:25Chuck Nice?

  Right.

• 10:26Neil deGrasse Tyson?

  And look how dim it is.

• 10:28Chuck Nice?

  Right.

• 10:28Neil deGrasse Tyson?

  Based on that, I can now give you the distance to that star with a simple formula.

• 10:34Chuck Nice?

  So then I guess you change it because there are a lot of different stars with different luminosities and some things that aren't even stars, you know?

• 10:43Neil deGrasse Tyson?

  Well, right, right. So, so, so that gets me to the distance to stars that look like the sun.

• 10:48Chuck Nice?

  Right, right.

• 10:48Neil deGrasse Tyson?

  Okay. But if I get a, a triangulated distance to a star that's not like the sun.

• 10:54Chuck Nice?

  Like a brown dwarf or something.

• 10:55Neil deGrasse Tyson?

  Like a brown dwarf or any, or a red giant or whatever.

• 10:57Chuck Nice?

  Red giant.

• 10:58Neil deGrasse Tyson?

  And I get the triangulated distance, now I find another star like that, and then I can apply the same method.

• 11:05Chuck Nice?

  Damn.

• 11:06Neil deGrasse Tyson?

  I know, I know.

• 11:07Chuck Nice?

  That is unbelievable. I'm telling you right now, my mind, I'm.

• 11:10Neil deGrasse Tyson?

  Okay. Now, now you wanna know, you know, you know, when we dunked on this, you ready?

• 11:17Chuck Nice?

  Go ahead.

• 11:18Neil deGrasse Tyson?

  Okay. Recently, there's a satellite called Gaia, G A I A, Gaia.

• 11:23Chuck Nice?

  Gaia.

• 11:23Neil deGrasse Tyson?

  Okay. Google it. It is a specially tuned satellite.

• 11:27Chuck Nice?

  Mm-hmm.

• 11:28Neil deGrasse Tyson?

  Designed to get this triangulated distance method to a billion stars. Because it's above Earth's atmosphere, it can measure the tiniest angles with very high precision.

• 11:41Chuck Nice?

  Damn.

• 11:41Neil deGrasse Tyson?

  Oh, my gosh. So now, we got that. We, we're good. We good. We can find these stars in other galaxies and get the distance there. By the way, that's what Hubble did.

• 11:51Chuck Nice?

  Right.

• 11:52Neil deGrasse Tyson?

  Hubble said, okay, here's a star that pulsates, okay? And, and it was discovered by Henrietta Leavitt, all right, in, in the women of Harvard College Observatory, who were given the quote, menial work of, of the laborers of calculating things with stars. They were called human computers. Turns out that's where all the action was. And modern stellar astrophysics was birthed in the room where it happened, okay? To quote, uh, Hamilton.

• 12:25Chuck Nice?

  Hamilton.

• 12:26Neil deGrasse Tyson?

  In the room where it happened, all the women, there's a bunch of women who all did this work, while the men stood up in their, in their smoking lounges.

• 12:33Chuck Nice?

  Right.

• 12:33Neil deGrasse Tyson?

  Believing they were contemplating the universe.

• 12:35Chuck Nice?

  Their pipes.

• 12:36Neil deGrasse Tyson?

  But the real action, with their pipes. The academics smoked the pipe.

• 12:40Chuck Nice?

  That's right.

• 12:41Neil deGrasse Tyson?

  Right. The gangsters, or no, the, the, the fat cat smoked the cigars.

• 12:44Chuck Nice?

  Fat cat smoked cigars and academics smoked pipes. I actually, when I had, there was a guy I went to school with, he was a philosophy major, and he smoked a pipe.

• 12:52Neil deGrasse Tyson?

  No, he didn't. No.

• 12:53Chuck Nice?

  Yes, I swear to God. I swear to God.

• 12:55Neil deGrasse Tyson?

  That ain't right. Okay.

• 12:56Chuck Nice?

  And yeah, and he, and everybody kinda, the, the people were like, what a, what a pompous pretentious ass, right? But then one day I just asked him, I was like, dude, seriously, why, why do you smoke a pipe? And he had the pipe when I asked him, and he went. Because it makes me look like I'm thinking about something when actually there's nothing on my mind.

• 13:19Neil deGrasse Tyson?

  Okay.

• 13:22Neil deGrasse Tyson?

  You got a head, that's good. You gotta give it to him.

• 13:23Chuck Nice?

  I was like.

• 13:24Neil deGrasse Tyson?

  Give it to him.

• 13:25Chuck Nice?

  I was like, hundred percent, you win.

• 13:28Neil deGrasse Tyson?

  You gotta know, there's no, there's no comeback on that one.

• 13:29Chuck Nice?

  Right.

• 13:30Neil deGrasse Tyson?

  Right. Um, so, so what, oh, let me, I'll end with this Hubble example. So we, uh, so Henry at eleven figured out that the rate at which the star pulsates directly correlates with the luminosity of the star. And again, all you need is the, if, all you have to do is know the lu, what is the luminosity? It's the wattage stamped on the light bulb. Okay? And so if you know that there's another light bulb with the same wattage, but it looks much dimmer, it's because it's farther away, because you otherwise can't see distance in the universe. There's no, the fact that you can't see distance led legions and generations of people to think

• 14:11Neil deGrasse Tyson?

  that the stars were just points of light on the inside of a dome.

• 14:16Chuck Nice?

  Right.

• 14:16Neil deGrasse Tyson?

  On the surface of a dome, leaving them to think that constellations were real things. Okay? But no, these are, they're scattered in space.

• 14:25Chuck Nice?

  Yes.

• 14:25Neil deGrasse Tyson?

  And since you, and they just did, uh, any other angle of view on them, they look completely different. They're not real things. They're completely in your head. Okay? So, so stars are scattered in space. So, but if, so once you knew this, Hubble found one of these variable stars in the Andromeda Nebula.

• 14:46Chuck Nice?

  Okay.

• 14:46Neil deGrasse Tyson?

  And then he measured its pulsation rate, deduced the luminosity, then calculated its distance, and ho, ho, it was a holy shit moment. This nebula is not in the Milky Way. It is way beyond the limits of the Milky Way.

• 15:03Chuck Nice?

  Right.

• 15:03Neil deGrasse Tyson?

  In fact, it's an entire other galaxy.

• 15:06Chuck Nice?

  Galaxy, right.

• 15:08Neil deGrasse Tyson?

  The Andromeda Nebula overnight became the Andromeda Galaxy.

• 15:13Chuck Nice?

  Oh, snap.

• 15:15Neil deGrasse Tyson?

  Yes, all of these got, we didn't know what they, these were just nebulae. We just called them nebulae, the fuzzy spiral thing.

• 15:21Chuck Nice?

  Fuzzy, right.

• 15:22Neil deGrasse Tyson?

  Why would, why would we think there's anything other than our own system? It's got a little bit of our ego playing out there. Okay? There's another island universe out there, an island galaxy, there it was. And then that opened up the entire universe. And that happened between nineteen twenty-six and nineteen twenty-nine. We're in this centennial decade of discovering how big the universe really is because of a distance method to determine, a method to determine the distance to this kind of variable star discovered by Henrietta Leavitt in the Harvard College Observatory. Unbelievable. There it is. That's amazing. Wait, then, once he got the distance to Andromeda, he could get distances to other galaxies

• 16:05Neil deGrasse Tyson?

  with methods similar, and then he found out that the galaxies are receding from us. And the farther away the galaxy is, the faster it's moving away. Well, if that's an actual relationship, then you don't need to separately know the distance, you just have to measure how fast it's moving away, which you could do using the Doppler shift. Just measure the speed moving away from us, and you put it in the Hubble equation and out pops the distance. So that is the ultimate, that's the highest rung of the distance ladder, what's called the redshift of the object, which was based ultimately on variable stars traceable to

• 16:46Neil deGrasse Tyson?

  nearby galaxies, traceable in our galaxy, traceable to the triangulation method, traceable all the way back to, just looking at stereoscopically with your eyes. Look at that. That's amazing. There it is. Well, Bruce, that was an extensive. I got one more. Wait, wait, wait, wait, wait. You gotta be kidding me. There can't be more. Okay, you ready? Okay, here it is. Okay? You can ask if there's an object where the angle changes by one arc second. Okay, an arc second is 1/60 of an arc minute. There's the angles now, even though it sounds like time, 1/60 of an arc minute, and an arc minute is 1/60 of a degree.

• 17:30Neil deGrasse Tyson?

  Okay, that's how small these angles are. Right. All right? Well, that makes sense. Okay, so we have degrees, minutes, seconds. So. If there were an object at a distance such that the this angle was one arc second. By the way, this, you know what we call this angle? Changing it up, we call it a parallax. Okay. You might have heard that word before. Yeah, yeah. The parallax is the angle change in a. It's a big deal. Have you ever been on? Big deal in 3D filmmaking. Okay, exactly. They care about that all the time. The bigger the parallax, the closer your brain. That's right.

• 18:10Neil deGrasse Tyson?

  The object to you. You use, your brain uses parallax to judge what's close and what's far. Okay? Alright. So, and the farther away it is, the lower the parallax. That's why the moon follows you when you walk. Oh, look at that! Wow! And here, I thought it was just me. The moon is so far away from you and your eyes. Right. That you don't see a change in the angle on it against the background. So it looks like it fell. Whereas the trees have very high parallax. Right. As you walk by them. So they have the highest parallax. The, the, the, the trees across the street have a lower parallax.

• 18:51Neil deGrasse Tyson?

  Buildings near the horizon, okay? Uh, the moon would eventually pass you by if you kept walking for another 300,000 miles. But that, that's, that's what you would need to get a big enough angle for that to happen. Alright, let me get back to this. So, an object whose parallax is one arc second is at a distance of one parsec.

• 19:16Neil deGrasse Tyson?

  What? That's amazing. That's where we get the distance parsec from. Look at that. Now, now I lied a little. It's a little more complicated. It's half angle is one arc second, just because that's how we define it. The angle that connects to the sun rather than to the full baseline. But that's just a geometric factor there. So, you heard parsec used in Star Trek and some other sci-fi thing. Every science fiction movie. And our boy in, in Star Wars did the Kessel Run in 12 parsecs. Right. Which is profoundly ignorant of what a parsec is. Because a parsec is a unit of distance, it's not a unit of time.

• 19:57Neil deGrasse Tyson?

  And then the apologists got online and said, here, Dr. Tyson, here's why he says parsecs. And it made up some total BS about it was a dista- he found a loop that was shorter, and that's why he did it in 12 parsecs instead of 15 parsecs. So they, and I said, all right, I'm staying away from this community of fans. There's no.

• 20:17Chuck Nice?

  Because Star Wars is magic.

• 20:21Chuck Nice?

  Let's, let's be honest.

• 20:23Neil deGrasse Tyson?

  So that's the whole, so I'm sorry, I blew half the time of this episode talking, but it was very important, and it took us, I would say, 60 years to fully develop that distance ladder, and we're still improving it. Oh, by the way, we later would find out that Hubble was using a different kind of variable star than the one Henry Etta-Levitt had used.

• 20:44Chuck Nice?

  Uh huh.

• 20:45Neil deGrasse Tyson?

  Um, but it's still correlated in that way, but it had a different correction factor. And once they corrected the factor, the size of the universe, was it doubled or halved? Again, because it was, it was the foundation for the later measurements.

• 20:58Chuck Nice?

  Right.

• 20:58Neil deGrasse Tyson?

  And so that, so that's how that, that, that uncertainty can creep in to the other measurements, but there it is.

• 21:06Chuck Nice?

  That's really cool. And all of that is in Cosmic Queries?

• 21:11Neil deGrasse Tyson?

  All of it, all of it, all of it, in a whole section called The Cosmic Distance Ladder.

• 21:15Chuck Nice?

  Look at that.

• 21:15Neil deGrasse Tyson?

  I guess now you don't have to buy the book, but you kind of do because you maybe go through it.

• 21:18Chuck Nice?

  Because you need to, you need to go ahead and get that information so that you can have it as a reference.

• 21:23Neil deGrasse Tyson?

  Yeah, it's a reference, and it's fully, it's more organizationally laid out than I could possibly deliver in this, uh, yeah, okay.

• 21:42Neil deGrasse Tyson?

  All right, what do you got?

• 21:43Chuck Nice?

  All right, this is Mike Parker, another, another great name.

• 21:47Neil deGrasse Tyson?

  Another good one, okay.

• 21:49Chuck Nice?

  He says, hello, Dr. Tyson and Chuck. Uh, Mike from Richmond, Virginia here. The James Webb Space Telescope is seemingly providing scientists with more questions than it is answers. What is, in your opinion, how can we be seeing massive galaxies just after the Big Bang? And what changes to cosmology do you see occurring as a part of the data so far? So. I mean, two questions, but why is it that James Webb sees things in a timeline

• 22:28Chuck Nice?

  much closer to the origin of the universe as opposed to other telescopes? And what do we know now that we didn't know before because we can see that?

• 22:45Neil deGrasse Tyson?

  Okay, so, so, a couple of things. First, I'm a, I'm actually an adopted son of Richmond, Virginia.

• 22:52Chuck Nice?

  Oh, really?

• 22:53Neil deGrasse Tyson?

  From Richmond? Yeah, I have an honorary doctorate from the University of Richmond.

• 22:57Chuck Nice?

  Oh, very cool.

• 22:58Neil deGrasse Tyson?

  Yes, I, yes, I do. So I think about Richmond often. And so, A.

• 23:03Chuck Nice?

  I've actually been to Virginia Beach.

• 23:06Neil deGrasse Tyson?

  Oh, okay, music festival there?

• 23:08Chuck Nice?

  Absolutely, yeah.

• 23:10Neil deGrasse Tyson?

  Yeah, all right.

• 23:11Chuck Nice?

  That's a great music festival.

• 23:12Neil deGrasse Tyson?

  So, uh, they said it seems that telescope is asking, is posing more questions than answers. That's what any good telescope ought to do.

• 23:22Chuck Nice?

  Okay.

• 23:22Neil deGrasse Tyson?

  So, in, in science, we have to learn to love the questions themselves.

• 23:27Chuck Nice?

  Yes.

• 23:28Neil deGrasse Tyson?

  Lest we become irritated by not having the answers we seek, or maybe the questions we ask are not even what should be asked.

• 23:38Chuck Nice?

  Right.

• 23:39Neil deGrasse Tyson?

  Because we don't know what question to ask because we're not standing in the right place yet to ask it.

• 23:43Chuck Nice?

  Sometimes you ask a question and it leads you to a better question.

• 23:48Neil deGrasse Tyson?

  For example, what kind of cheese is the moon made out of?

• 23:52Chuck Nice?

  Right.

• 23:53Neil deGrasse Tyson?

  That question has no meaning, but if you set up devices, you go to the moon and you say, no, there's, it's, in fact, it's not made of any kind of cheese.

• 24:00Chuck Nice?

  Right.

• 24:01Neil deGrasse Tyson?

  Maybe it's made of rocks, okay? So.

• 24:03Chuck Nice?

  There you go.

• 24:04Neil deGrasse Tyson?

  So, a good experiment will be a launch pad for other questions. So, indeed, the telescope discovered five galaxies, was it six or five, that, where they, where the sun don't shine, where it ain't supposed to be. This telescope is exquisitely tuned to observe the birth of galaxies. So it is going right where we wanted it to go, and we don't have a good answer to it yet.

• 24:28Chuck Nice?

  Okay, excellent.

• 24:29Neil deGrasse Tyson?

  Do we, maybe we don't understand the birth of galaxies enough to put them there in our distance calculation, right? Is our distance, we just spent a whole time talking about the distance ladder, maybe there's some failure of the distance ladder at that point. Or we just don't understand how matter goes from. Energy and matter into solid objects.

• 24:52Chuck Nice?

  Right.

• 24:53Neil deGrasse Tyson?

  All right. So, yeah.

• 24:55Chuck Nice?

  Wow, that's.

• 24:56Neil deGrasse Tyson?

  So, so we're not disturbed by this. We are overjoyed that we are stumped. And we spend, we spend most of our lives stumped at the chalkboard.

• 25:04Chuck Nice?

  There you go.

• 25:04Neil deGrasse Tyson?

  What are the drawing board, the whiteboard, right?

• 25:07Chuck Nice?

  That's very cool, you know? And by the way, uh, it don't have to be a whiteboard. There's also.

• 25:15Chuck Nice?

  That's right. That's all I'm saying. Okay, I'm just saying.

• 25:22Neil deGrasse Tyson?

  So, yeah, it's, it's, it's not a problem. It's a, it's a wonderful challenge that we're all scratching our heads over.

• 25:29Chuck Nice?

  Awesome. All right, let's go to Colin Brum. And Colin says, greetings from a small town in Iowa. I have a question about dark matter. If it is rarely or completely non-self-interacting, shouldn't the majority of dark matter particles fall directly to the center of galaxies? Since there's effectively nothing stopping them. Is this a contributing factor to how possibly supermassive black holes got so big? So, he says supermassive black holes.

• 26:02Neil deGrasse Tyson?

  Dark matter is, is, is, is mysterious gravity.

• 26:06Chuck Nice?

  Right.

• 26:06Neil deGrasse Tyson?

  Know what it is. It's literally dark gravity. It has gravity. We don't know what's causing it.

• 26:11Chuck Nice?

  Right.

• 26:11Neil deGrasse Tyson?

  It's not black holes. It's not dark clouds. It's not comets, asteroids.

• 26:15Chuck Nice?

  Right.

• 26:16Neil deGrasse Tyson?

  It's, it's no ordinary matter is causing what we're calling dark matter. It's the longest unsolved problem in modern astrophysics. It's been with us for 90 years.

• 26:25Chuck Nice?

  Right.

• 26:25Neil deGrasse Tyson?

  Since the 1930s. Okay? So, just let's put it out there.

• 26:30Chuck Nice?

  Okay.

• 26:30Neil deGrasse Tyson?

  So now, um, here's what's interesting about dark matter. A property not shared with ordinary matter. Ordinary matter, when it collapses, it sticks together.

• 26:42Chuck Nice?

  Right.

• 26:44Neil deGrasse Tyson?

  Because other forces, other, well, gravity will, will take it at, once it comes together, molecular forces kick in where you get solid objects.

• 26:54Chuck Nice?

  Right.

• 26:55Neil deGrasse Tyson?

  Okay? What's holding a rock together? It's not gravity.

• 26:58Chuck Nice?

  No.

• 26:58Neil deGrasse Tyson?

  It's electromagnetic forces. What's holding you together? Me together?

• 27:02Chuck Nice?

  Right.

• 27:02Neil deGrasse Tyson?

  It's electromagnetic force holding our molecules together. No such corresponding force holds dark matter together.

• 27:10Neil deGrasse Tyson?

  So, people say, "Well, could we find dark matter galaxies, dark matter planets?" Everything we know about dark matter says it cannot coalesce into, quote, "solid dark matter" objects. It would just pass, because not only does dark matter not interact with us, it doesn't interact with itself. Okay, so it'll feel its gravity, but there's no place of concentration for it. It'll just continually move through space, hanging out in the hood, but not causing discrete dense objects. And so, we have no expectation that dark matter played any role in the formation of black holes.

• 27:53Neil deGrasse Tyson?

  Even though the formation of supermassive black holes remains a little bit mysterious to us.

• 27:57Chuck Nice?

  And guess what? If it's not interactive, it wouldn't be interactive with the black hole anyway. Or, it wouldn't be feeding the black hole.

• 28:06Neil deGrasse Tyson?

  No, no, but what it would do, yeah, so where the mass is, so this mass blob called dark matter does attract regular matter into the blob. It will do that, okay? Okay, so, regular matter is like the froth in the ocean, in the waves of the ocean. There are these huge waves, which we don't see, and regular matter is the froth. But you look at the froth, the froth are these little things, the wave is huge.

• 28:32Chuck Nice?

  That's great, that's great, that's great.

• 28:34Neil deGrasse Tyson?

  Compared to the froth, the waves are huge. So, the dark matter is spread out over the galaxy clusters, over the galaxy, but you can't point to one spot and say, "There's where the dark matter is hanging out, that spot, that's gonna pull you in." No, it's a general gathering of regular matter in the vicinities of dark matter.

• 28:52Chuck Nice?

  So, wow, look at that. So, there are causal effects, but it is not interacting with us.

• 29:01Neil deGrasse Tyson?

  Correct, correct. And that matters. If you don't interact, you can't make an object. We don't think about it that way, but, you know, when you make a snowball, what are you doing? You're squeezing it so that the snow sort of melts under pressure, and it makes a solid object. So, there's a lot we take for granted about why things stick together in our world, but in the world of dark matter, that it's not the case.

• 29:26Chuck Nice?

  Wow, okay, man. Thank you, Colin. What a great question.

• 29:39Speaker 02

  Hey, I'm Roy Hill Percival and I support StarTalk on Patreon. Bringing the universe down to earth, this is StarTalk with Neil deGrasse Tyson.

• 29:55Chuck Nice?

  Hey, let's go to our old friend, Kevin the Sommelier.

• 29:58Neil deGrasse Tyson?

  Kevin the Sommelier.

• 29:59Chuck Nice?

  Kevin the Sommelier, who says, "Hey!"

• 30:02Neil deGrasse Tyson?

  It's a prerequisite, we gotta know what wine he's recommending for this question.

• 30:05Chuck Nice?

  And you know what? He didn't give, I can't believe it, he didn't give us, "Hey Kevin, man, what's the problem?" You normally give us a little-

• 30:11Neil deGrasse Tyson?

  So Kevin, if you're gonna be on online here-

• 30:13Chuck Nice?

  Exactly, man.

• 30:14Neil deGrasse Tyson?

  Hook us up, okay. Skip this now. No, no.

• 30:19Neil deGrasse Tyson?

  Skip his ass, that'll-

• 30:23Neil deGrasse Tyson?

  Alright.

• 30:24Chuck Nice?

  Alright.

• 30:24Neil deGrasse Tyson?

  I know, we're, uh, we're recording this at a time that's approaching the holiday season, so a glass of port would be very-

• 30:31Chuck Nice?

  Oh, look at that. Are you a Tony man, or?

• 30:34Neil deGrasse Tyson?

  Uh, I'm a, I can do Tony and Ruby.

• 30:36Chuck Nice?

  You can do Ruby?

• 30:37Neil deGrasse Tyson?

  Different moves, yeah.

• 30:38Chuck Nice?

  Alright, okay.

• 30:39Neil deGrasse Tyson?

  Okay.

• 30:39Chuck Nice?

  So, uh, Kevin's-

• 30:40Neil deGrasse Tyson?

  There I am, doing your work for you.

• 30:42Chuck Nice?

  There you go, Kevin, look at that.

• 30:44Neil deGrasse Tyson?

  Alright.

• 30:44Chuck Nice?

  Kevin says, "I read there were discoveries of galaxies forming in the cosmic dark ages."

• 30:52Neil deGrasse Tyson?

  Yes, this is what the other question was about.

• 30:54Chuck Nice?

  Right.

• 30:54Neil deGrasse Tyson?

  That's what, because it's before stars formed.

• 30:56Chuck Nice?

  Right.

• 30:57Neil deGrasse Tyson?

  So we called it the Dark Ages, and we didn't expect to find anything there, and there they were.

• 31:01Chuck Nice?

  And there they were. Exactly.

• 31:02Neil deGrasse Tyson?

  Yes, okay.

• 31:03Chuck Nice?

  So, does this put us back on the age of the universe, the coalescence factor, and then we originally thought? So, but we don't know.

• 31:09Neil deGrasse Tyson?

  Yeah, yeah, so that's the same, basically the same question.

• 31:12Chuck Nice?

  Same question.

• 31:13Neil deGrasse Tyson?

  Uh, we don't know. We got top people working on it, and we're still scratching our heads. There it is.

• 31:18Chuck Nice?

  So this is Fadi Hayek, and Fadi Hayek says, "Hello, Dr. Tyson, Lord Nice. This is Fadi Hayek from Indianapolis in Indiana. On the nature of the expansion of the universe..."

• 31:32Chuck Nice?

  Is it that the galaxies are racing away from each other into nothingness? Or that the fabric of space-time is dilating while the relatively distance between the galaxies is really not affected? Or is the expansion a mere deep field effect created by fundamental misinterpretation as to why redshifting exists? Look at that. He's so he's got three things. He's everywhere with this question. He's all over.

• 32:04Neil deGrasse Tyson?

  All over and in it. So, no, it's a simple, it's a simple answer. So, other than what we call random motions, but they're not really random. We call them that. Random motions of galaxies near each other. So, we're falling towards Andromeda. That's a nearby galaxy. There's some other galaxies in clusters. You take a step back and you look at the large-scale structure of the universe. Galaxies are moving away from one another. If you just take a step back. When you get up close, the ones near each other will be in orbit. But take a step back, clusters of galaxies, even isolated galaxies, all moving away from one. They're embedded in the fabric of space and time and is that fabric that is itself stretching,

• 32:49Neil deGrasse Tyson?

  carrying the galaxies along with it, as though you drew on the surface of a balloon. And then you started inflating the balloon. And then the fabric of the balloon is stretching. The galaxies are not separating from each other within the balloon itself. They're embedded in the surface and the surface is stretching. That is the signature of the expanding universe and we measure that.

• 33:09Chuck Nice?

  Look at that.

• 33:10Neil deGrasse Tyson?

  Yeah.

• 33:10Chuck Nice?

  Fantastic. It's a great question, man. Jaden Peters says, greetings, Dr. Tyson. Jaden Peters, aspiring astrophysicist from Ogden, Utah here.

• 33:23Neil deGrasse Tyson?

  Nice, nice.

• 33:24Chuck Nice?

  I currently help to manufacture the motors for the Artemis programs. It's my first time asking a question and I'm extremely excited to do so. So, my man, look at that. Well, listen.

• 33:36Neil deGrasse Tyson?

  Artemis is the NASA's return to the moon.

• 33:39Chuck Nice?

  To the moon.

• 33:39Neil deGrasse Tyson?

  And Artemis in Greek mythology is the twin sister of Apollo.

• 33:44Chuck Nice?

  Oh, look at that. And by the way, if anything goes wrong with the mission, we know now who to blame.

• 33:49Neil deGrasse Tyson?

  Oh, he called himself.

• 33:51Chuck Nice?

  Sorry, sorry, Jayden.

• 33:53Neil deGrasse Tyson?

  Called himself out, alright.

• 33:55Chuck Nice?

  That's right. So, uh, my question is as follows, he says, what are the necessary technologies for alien life to visit us? And is it likely that aliens have any interest in Earth at all? If they are so technologically superior to us to allow interstellar travel, what use could they possibly have for Earth? Thank you so much.

• 34:15Neil deGrasse Tyson?

  So first, I agree in principle that why would we be interesting to them at all with our backwards-ass technologies if they have interstellar space travel? However, they might be interested in just life existing anywhere in the universe, as are we. We're searching other planets for life of any kind.

• 34:33Chuck Nice?

  Right.

• 34:33Neil deGrasse Tyson?

  If we found microbial life, that would be amazing.

• 34:36Chuck Nice?

  Right.

• 34:36Neil deGrasse Tyson?

  Worms, octopoids, whatever, we would find that amazing for our biologists. So I don't want to deny them the, the power of curiosity to see all the ways life can, that matter can manifest as life.

• 34:52Chuck Nice?

  Mm-hmm.

• 34:53Neil deGrasse Tyson?

  In the galaxy or across the universe. That's my first reply. Second, uh, maybe they live much longer than we do.

• 35:01Chuck Nice?

  And that would be the real issue.

• 35:02Neil deGrasse Tyson?

  Yeah, if they live a billion years, then so what if it takes them, you know, a hundred thousand years or half a million years to, to travel?

• 35:10Chuck Nice?

  Get somewhere.

• 35:11Neil deGrasse Tyson?

  I wouldn't care. Yeah, yeah. So that's one factor. Second factor, if they do have our limited life expectancy, then they would need something like wormholes.

• 35:19Chuck Nice?

  Right.

• 35:20Neil deGrasse Tyson?

  Wormholes. Without wormholes, uh, which are portals through the fabric of spacetime, where you don't have to traverse the entire path. You should just cut a hole through.

• 35:29Chuck Nice?

  Yeah.

• 35:30Neil deGrasse Tyson?

  Sorry for those who are only listening to this podcast, but I have a wormhole in my hand.

• 35:35Chuck Nice?

  Look at that.

• 35:35Neil deGrasse Tyson?

  And it is, you see the fabric of space and time as this ribbon, and the ribbon is curved.

• 35:42Chuck Nice?

  Mm-hmm.

• 35:42Neil deGrasse Tyson?

  And the two edges of the ribbon are connected by two sort of dimples.

• 35:47Chuck Nice?

  Right.

• 35:47Neil deGrasse Tyson?

  And you can trap, you can cross this dimple without having to go the full length of this journey.

• 35:54Chuck Nice?

  Right.

• 35:55Neil deGrasse Tyson?

  To get to where you're going. And so this curvature of space enables this wormhole to, to exist. And so then you just jump through the wormhole and you get there instantly.

• 36:05Chuck Nice?

  That's right, yeah.

• 36:06Neil deGrasse Tyson?

  If we had wormhole, if Star Trek had wormholes, they wouldn't need transporters.

• 36:10Chuck Nice?

  No, exactly. And you certainly wouldn't need warp drives.

• 36:12Neil deGrasse Tyson?

  You wouldn't, you wouldn't even need warp drive.

• 36:14Chuck Nice?

  Yeah.

• 36:14Neil deGrasse Tyson?

  You just, you just open up a wormhole.

• 36:16Chuck Nice?

  Just open up the wormhole and get to where you're going.

• 36:18Neil deGrasse Tyson?

  Definitely. And you know who does that every episode is Rick.

• 36:21Chuck Nice?

  Rick and Morty.

• 36:22Neil deGrasse Tyson?

  On Rick and Morty.

• 36:23Chuck Nice?

  Yeah.

• 36:23Neil deGrasse Tyson?

  You know, does it on every movie?

• 36:25Chuck Nice?

  Uh, no.

• 36:26Neil deGrasse Tyson?

  Doctor Strange.

• 36:27Chuck Nice?

  Oh, yeah. Okay.

• 36:29Neil deGrasse Tyson?

  He just, but he does it with magic.

• 36:31Chuck Nice?

  Yes.

• 36:31Neil deGrasse Tyson?

  Whereas Rick does it with science. I just wanted to distinguish those two.

• 36:34Chuck Nice?

  Yeah.

• 36:34Neil deGrasse Tyson?

  Okay.

• 36:35Chuck Nice?

  Exactly.

• 36:40Neil deGrasse Tyson?

  In case you were curious.

• 36:41Chuck Nice?

  Yeah, yeah, exactly.

• 36:42Neil deGrasse Tyson?

  Mm-hmm.

• 36:44Chuck Nice?

  We don't, we don't want to demean Rick's accomplishments.

• 36:48Neil deGrasse Tyson?

  Exactly, exactly, exactly.

• 36:51Chuck Nice?

  Yeah, that's very cool, man.

• 36:52Neil deGrasse Tyson?

  Mm-hmm. All right. I'll tell you like one more question. What do you have?

• 36:55Chuck Nice?

  Oh, that's all. Damn.

• 36:56Neil deGrasse Tyson?

  I know, cause I blew the, half the show answering the distance.

• 36:59Chuck Nice?

  Yeah, well, I gotta tell you.

• 37:01Neil deGrasse Tyson?

  Didn't buy the book, apparently.

• 37:02Chuck Nice?

  Well, all right. This is Christopher Pence, uh, who says, hey, Chris Pence here from San Diego, California. Fairly new to Patreon and not sure if this has ever been covered, but are there any theories out there about dark matter converting into dark energy in any way? Do they relate to each other like normal matter and normal energy? Thank you for all that you do and I absolutely love StarTalk.

• 37:34Neil deGrasse Tyson?

  Excellent, excellent. Man, we would have put his question on even if he didn't end it with that.

• 37:39Chuck Nice?

  However, uh, to anybody who writes in, feel free to kiss our ass whenever you.

• 37:45Chuck Nice?

  I'm all about it. I am all about it. Love you for it. Love you for it. And everybody needs encouragement. It's so much negativity in the world.

• 37:56Neil deGrasse Tyson?

  Oh, that's true.

• 37:57Chuck Nice?

  That's right. Anytime you want to put a little lip print on the posterior, I'm like, kudos to you. Thank you so much.

• 38:05Neil deGrasse Tyson?

  I forgot the question. What was he? Oh, oh, okay. Could one do? Okay, so don't overread into the fact that we call one dark energy and the other dark matter.

• 38:13Chuck Nice?

  Right.

• 38:14Neil deGrasse Tyson?

  Because we don't know what either of them is. And I've said this, what we call Fred and Wilma. That would be just as accurate as calling it dark energy and dark, dark matter. So, so Fred and Wilma, then you're not biased in what you think it could be.

• 38:27Chuck Nice?

  Right.

• 38:27Neil deGrasse Tyson?

  Because we don't know what it is. So, um, could dark matter ever turn into dark energy? The properties of these two entities are, are so, maybe, but I don't see evidence of that. Because, um, as the universe expands, there's more dark energy in it. But there's not more dark matter. There's not more gravity. We haven't seen this effect. So of one converting to the other. Could you see the effects of one diminish and the effects of the other increase? And we don't see that happening. So I have to say no.

• 39:03Chuck Nice?

  Okay. That's pretty cool. I mean, that makes sense.

• 39:07Neil deGrasse Tyson?

  Yeah. Chuck, give me one more and I'm going to soundbite it and then we got to call it up.

• 39:12Chuck Nice?

  Hmm, okay. Um, this is Charles, uh, Mako. And he says, hey, Dr. Tyson, and I'm guessing Chuck, um.

• 39:26Neil deGrasse Tyson?

  Okay. That's what he said?

• 39:28Chuck Nice?

  Yes, that's exactly.

• 39:29Neil deGrasse Tyson?

  Occasionally we have other comedians in that place.

• 39:31Chuck Nice?

  So he's like, I'm guessing it's going to be Chuck. He says, how has the JWST changed our understanding of the universe itself? And will it lead to the rewriting of textbooks?

• 39:49Neil deGrasse Tyson?

  Hmm. Any textbook that talks about the latest discovery is always being rewritten. But textbooks that talk about discoveries that are time-tested with experiments and observations and repeated experiments, that stays the same. So textbooks, they always want to be evergreen, but no one is going to buy them if it's not current. So textbooks have this issue. And that's why an online textbook is better, because you can update it in real time as you need it to. So some things will be rewritten, but it's because they weren't ever fully established in the first place. But they put something in there. Here's our latest thinking on cosmology. Yeah. So we'll see. It's a new telescope in a new window on the universe.

• 40:34Neil deGrasse Tyson?

  And for every new window that has ever been opened in the history of my field, it has transformed our understanding of the field in the areas where it specialized in. So I fully expect that to happen in the days, weeks, and years to come. Also, the James Webb Space Telescope is just the next telescope. We're thinking of other stuff even beyond this. Right. We're thinking of a 3D meteor telescope. Oh, my gosh. Which would be far and away the largest telescope ever on Earth or in space to see things dimmer than ever previously imagined.

• 41:16Neil deGrasse Tyson?

  Because if you don't have all the contents of the universe and you try to develop hypotheses and theories based on it, and then someone says, "Wait a minute, guys, there's a whole other category of object that you didn't see because your telescopes weren't powerful enough to see it." That's embarrassing. Right. But that's the way of science. It's you do the best you can at any given moment. But like I said, in the end, we all must learn to love the questions themselves.

• 41:42Chuck Nice?

  There you have it.

• 41:43Neil deGrasse Tyson?

  There it is.

• 41:45Chuck Nice?

  Awesome.

• 41:45Neil deGrasse Tyson?

  All right, Chuck, we gotta close out.

• 41:47Chuck Nice?

  Well, that was great. That was a lot of fun. I gotta tell you.

• 41:50Neil deGrasse Tyson?

  All right, all right, all right. And so another episode of Cosmic Queries. And that one was almost all purely about galaxies.

• 41:58Chuck Nice?

  That was all galaxies.

• 42:00Neil deGrasse Tyson?

  It was mostly galaxies.

• 42:01Chuck Nice?

  Well, yeah, a little dark matter, you know, but I mean, dark matter counts as, you know, galaxies because, well, it doesn't.

• 42:09Neil deGrasse Tyson?

  Exactly. No, galaxies have dark matter as part of it.

• 42:11Chuck Nice?

  That's right. You know what I mean?

• 42:13Neil deGrasse Tyson?

  That's right. Very loosely held part.

• 42:15Chuck Nice?

  Loosely held part of it, so.

• 42:16Neil deGrasse Tyson?

  You got it. All right, Chuck, always good to have you.

• 42:18Chuck Nice?

  Always a pleasure.

• 42:19Neil deGrasse Tyson?

  All right, Neil deGrasse Tyson here. For StarTalk, as always, I bid you to keep looking up.