Cosmic Queries – Edge of the Universe

What lies beyond the edge of the universe? Neil deGrasse Tyson, comic co-host Chuck Nice, and astrophysicist Janna Levin, PhD, answer your fan-submitted Cosmic Queries about higher dimensions, the multiverse, the Big Bang, and much, much more! NOTE: StarTalk+ Patrons and All-Access subscribers can watch or listen to this entire episode commercial-free here: https://www.startalkradio.net/show/cosmic-queries-edge-of-the-universe/ Thanks to this week’s Patrons for supporting us: Paul Love, Sharon Coates, Jon Duey, Roy Hill-Percival, Jose Clark, Dr. Janet L. Walsh. Photo Credit: Image Credit: X-ray: NASA/CXC/SAO/G. Schellenberger et al.; Optical: SDSS.

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

• 0:00Neil deGrasse Tyson?

  From the American Museum of Natural History in New York City, and beaming out across all of space and time, this is StarTalk, where science and pop culture collide. This is StarTalk. I'm your host, Neil deGrasse Tyson, your personal astrophysicist. Today, we're doing cosmic queries. Topic: The edge of spacetime. The edge of the universe. Chuck?

• 0:30Chuck Nice?

  Hey Neil.

• 0:30Neil deGrasse Tyson?

  You gonna join me there?

• 0:31Chuck Nice?

  I am.

• 0:31Neil deGrasse Tyson?

  But we can't do it alone.

• 0:32Chuck Nice?

  And that shirt.

• 0:38Neil deGrasse Tyson?

  You know, you know, whether you're watching or listening, that I wear cosmically colorful clothing.

• 0:43Chuck Nice?

  Yes.

• 0:44Neil deGrasse Tyson?

  But my shirt I'm wearing today is particularly cosmically colorful.

• 0:49Chuck Nice?

  Yes.

• 0:49Neil deGrasse Tyson?

  It's in your face. It's smackdown. It's...

• 0:54Chuck Nice?

  Well, you're gonna have to go to Patreon, or maybe we'll take a picture of it and you'll have to see it on our website, or maybe you'll see it on YouTube, but you gotta see this shirt. Seriously.

• 1:03Janna Levin?

  It's some pretty lovely celestial bodies going on there.

• 1:05Neil deGrasse Tyson?

  We have Janet Levin to help us.

• 1:06Chuck Nice?

  Yeah!

• 1:07Janna Levin?

  Always glad to be here.

• 1:08Neil deGrasse Tyson?

  Professor Physics, Barnard College, Columbia University. Welcome back!

• 1:11Janna Levin?

  I love being here.

• 1:12Neil deGrasse Tyson?

  We needed you.

• 1:13Janna Levin?

  Great.

• 1:14Neil deGrasse Tyson?

  For this topic. Because my knowledge of cosmology is little, and yours is big.

• 1:18Janna Levin?

  Not, not as big.

• 1:20Neil deGrasse Tyson?

  As the universe itself, okay. All right. So anytime we, we, we do a cosmic queries,

• 1:26Chuck Nice?

  Right.

• 1:27Neil deGrasse Tyson?

  we bring it in.

• 1:27Janna Levin?

  I love it.

• 1:28Neil deGrasse Tyson?

  We bring in the big guns.

• 1:29Chuck Nice?

  This is, and Janet is the big guns, man.

• 1:31Neil deGrasse Tyson?

  Right, right.

• 1:32Chuck Nice?

  Yeah, good stuff.

• 1:33Neil deGrasse Tyson?

  So what do you have?

• 1:34Chuck Nice?

  So we got cosmic queries as, as we glean from all over the internet, and of course, we always start with a Patreon patron because these people...

• 1:40Neil deGrasse Tyson?

  Just a quick sec. You, so, your book, Black Hole Blues.

• 1:43Chuck Nice?

  Yeah.

• 1:43Neil deGrasse Tyson?

  That's still out there.

• 1:44Janna Levin?

  Yeah, it's still out there.

• 1:45Neil deGrasse Tyson?

  Okay Chuck, we gotta do it.

• 1:47Chuck Nice?

  Black Hole Blues.

• 1:51Janna Levin?

  I've gotta learn a harmony to that, so I can be like, over here.

• 1:55Neil deGrasse Tyson?

  There's gotta be a way where someone picks up the book, it says...

• 1:59Chuck Nice?

  Black Hole Blues.

• 2:01Neil deGrasse Tyson?

  Guaranteed more sale.

• 2:02Janna Levin?

  What if you just, every time you walk past it on the shelf?

• 2:04Neil deGrasse Tyson?

  Oh, you just heard it.

• 2:05Chuck Nice?

  Ah, that's so cool.

• 2:07Janna Levin?

  We gotta put it on your shelf, right right here.

• 2:09Chuck Nice?

  With a little riff behind it, you know? Black hole blues.

• 2:13Neil deGrasse Tyson?

  So that was about the discovery of gravitational waves.

• 2:17Janna Levin?

  Yeah, so.

• 2:18Neil deGrasse Tyson?

  Moving through the universe.

• 2:19Janna Levin?

  Yeah, exactly. So right, right before that succeeded, in the 50 years it took them to succeed.

• 2:24Neil deGrasse Tyson?

  Before we successfully measured it.

• 2:25Janna Levin?

  Yeah, Ray Weiss, who was one of the original architects, just was shaking his head and saying, you know, we don't detect black holes, this thing is a failure. So like, the whole title was just kind of like, it's the black hole blues.

• 2:37Neil deGrasse Tyson?

  But then he detected it, so he got a new title?

• 2:40Janna Levin?

  The new title is called Nobel Prize winner.

• 2:43Neil deGrasse Tyson?

  Black hole Nobel Prize.

• 2:45Chuck Nice?

  The Nobel Prize jig.

• 2:47Neil deGrasse Tyson?

  He said all the way to the bank on that one, yeah.

• 2:49Chuck Nice?

  Nice.

• 2:51Neil deGrasse Tyson?

  All right, so get to here till after.

• 2:52Janna Levin?

  Yes, thank you for that.

• 2:54Chuck Nice?

  Let's start off though with a Patreon patron. Uh, this is Chris Hampton, who supports us on Patreon, who wants to know this. Could it be that the universe that we are in is actually finite? However, the universal structure is infinite via size and relativity. Uh, meaning the universal structure gets infinitely smaller and vice versa. Kind of like infinitely dividing in half. I imagine it would look something like a very complex fractal.

• 3:23Neil deGrasse Tyson?

  Well, he's going a lot of places.

• 3:26Neil deGrasse Tyson?

  Again, take that however you want to do it.

• 3:28Janna Levin?

  I'm gonna write.

• 3:29Chuck Nice?

  And I have a question for Chris first. Um, is it sativa or endica? Sativa? Endica? Okay.

• 3:40Janna Levin?

  Which is the one that he would have fallen asleep before making it to the end of the tweet?

• 3:45Neil deGrasse Tyson?

  Not the sativa.

• 3:46Chuck Nice?

  I think that, I don't know.

• 3:47Janna Levin?

  I don't know. Okay, well, we just all revealed our, like.

• 3:50Chuck Nice?

  When I, when I, when I actually used that substance, it was called weed. They didn't put any other name on it. Like, if you went to your.

• 3:58Neil deGrasse Tyson?

  Easy, easy to pronounce and remember.

• 4:00Chuck Nice?

  That was it, right. If, if you went to your dealer and you went, so now is this sativa or endica? He'd be like, man, what's wrong with you? Smoke it. Get the hell out of my, get out of my house. Go smoke that and get out.

• 4:13Neil deGrasse Tyson?

  Anyway, so you wanna take a shot at this?

• 4:15Janna Levin?

  I'm into this, I'm into this.

• 4:16Neil deGrasse Tyson?

  Okay.

• 4:17Janna Levin?

  So, uh, my first book is about whether or not the universe is infinite or finite. It's a question, we don't know the answer.

• 4:23Neil deGrasse Tyson?

  And title of that book?

• 4:24Janna Levin?

  Yeah, uh, How the Universe Got Its Spots.

• 4:25Neil deGrasse Tyson?

  I remember that, yeah.

• 4:26Janna Levin?

  So How the Universe Got Its Spots is about, could we tell the shape and size of the universe by looking at the hot and cold spots in the Big Bang, in the light left over from the Big Bang? But, but the question, let's just take it really theoretically, we absolutely do not know that the universe is infinite. And, uh, it may well be that it's finite, the way the Earth is finite, that, you know, we leave New York City, we travel in a straight line, maybe we'd have to swim a little, get on a boat, but you travel in a straight line, you're gonna come back to New York City again. And so it could be that we-

• 4:55Neil deGrasse Tyson?

  But you can travel forever.

• 4:57Chuck Nice?

  I was gonna say, it's infinite in what you can tra- in where you can travel.

• 5:01Neil deGrasse Tyson?

  It's in- infinite in you don't get to an edge.

• 5:03Chuck Nice?

  Right.

• 5:04Janna Levin?

  You never get to an edge, which is beautiful. So exactly the same thing with the universe, you're not gonna sail off the edge of the Earth, right? Like, you know, Spanish explorers waved goodbye and wondered, right, if they'd just go off the side, but no, we know that's not what happens, and so similarly, we could leave the Milky Way galaxy, we could watch it recede behind us, we could travel in as straight a line as possible and find ourselves coming back to the Milky Way again.

• 5:26Neil deGrasse Tyson?

  Wow.

• 5:27Janna Levin?

  You know, and it's, it's so Planet of the Apes, right? It's like-

• 5:29Neil deGrasse Tyson?

  Damn you!

• 5:30Janna Levin?

  Yay!

• 5:31Neil deGrasse Tyson?

  You finally did it! Damn you all to hell!

• 5:34Chuck Nice?

  Oh, that'd be great.

• 5:36Janna Levin?

  So my interpretation of that was that they went all the way around. Yeah. And so the interesting thing is that also means that if you look at distant galaxies, the light is also traveling all the way around the universe, so it could be that some of those distant galaxies are the Milky Way, and we're seeing the light from the Milky Way wrap all the way around and come back to us, we'd be seeing the Milky Way in the past.

• 5:58Neil deGrasse Tyson?

  Wow.

• 5:59Janna Levin?

  So it would be hard to know, like, maybe we'd see an active black hole quasar with jets flying out in the early phases of the Milky Way, and we'd think, oh, that's just a different galaxy.

• 6:08Neil deGrasse Tyson?

  Oh.

• 6:09Chuck Nice?

  Wow!

• 6:10Janna Levin?

  Yeah, so we-

• 6:11Neil deGrasse Tyson?

  Because galaxies, they're- Young galaxies look very different from mature galaxies.

• 6:16Chuck Nice?

  Right.

• 6:16Neil deGrasse Tyson?

  And we used to think that they were different kinds of objects in the outer universe, like quasars. Why are they all distant? How comes there's not a quasar right next door? With these monstrous nuclear emissions? And we had to like, figure out that it's, it's likely just younger galaxies. And maybe we used to look like a quasar and we don't anymore.

• 6:37Janna Levin?

  Right. So even a distant galaxy looking back at us is seeing us in the past, given the light travel time. So we could still look like a quasar to a distant galaxy. Like we're, I have this huge active galactic nucleus.

• 6:51Chuck Nice?

  Cause they're not seeing us as we are now.

• 6:52Janna Levin?

  No, they're not.

• 6:53Chuck Nice?

  They're seeing us as we were.

• 6:54Janna Levin?

  Billions of years ago.

• 6:56Chuck Nice?

  Wow. Oh my god.

• 6:57Janna Levin?

  So that's the beauty, we get to see in the past.

• 6:59Chuck Nice?

  I need some of that's the diva right now.

• 7:03Chuck Nice?

  Wow.

• 7:04Janna Levin?

  Well, and then it gets more because there are reasons that people start to suspect that there are extra spatial dimensions and that they are not only finite, but really technically really small. Like that journey to go all the way around them is something that would, would happen incredibly quickly. And it's too small for us to like literally stick our hands in that direction, in some sense. So we, we're looking everywhere. Those extra dimensions are everywhere, but we can't actually notice them.

• 7:30Neil deGrasse Tyson?

  What does that mean for a dimension to be smaller than another dimension? What does that even mean?

• 7:34Janna Levin?

  So think of like a straw is a good example where it's a two dimensional surface.

• 7:39Neil deGrasse Tyson?

  You know what the first straws were made of?

• 7:42Chuck Nice?

  I'm gonna go with flax.

• 7:43Neil deGrasse Tyson?

  No. Yeah, straw, straw, yeah, yeah.

• 7:45Chuck Nice?

  Thank you. Thank you for getting that. I knew I could make that joke to him. I know it. Oh, god.

• 7:52Janna Levin?

  The only reason I would, it's cause flax and hair.

• 7:55Chuck Nice?

  Oh, yeah?

• 7:55Janna Levin?

  Yeah, that's the only reason why I would have the connection between flax and straw. So, so a straw is small in one direction on the surface, right? If you, you think there's a direction in which it's totally wrapped up and small. And then there's a long direction.

• 8:12Neil deGrasse Tyson?

  So straws are mostly long?

• 8:13Janna Levin?

  They're mostly long. And you could glue the top end to the bottom end of a straw to make that long direction also finite. So then you did travel around the world. It could be really big, it could be, you know, a mile around. But still be connected. But it's only a few millimeters around in this direction.

• 8:31Neil deGrasse Tyson?

  In this other dimension.

• 8:32Janna Levin?

  So literally, the length of traveling before you come back to where you started is smaller.

• 8:37Neil deGrasse Tyson?

  So most of how you use a straw does not access that other dimension. It's only the length, because you're trying to get the liquid from here to here.

• 8:43Janna Levin?

  Yeah.

• 8:44Neil deGrasse Tyson?

  And so, most of your, you're using the long dimension of the straw.

• 8:48Janna Levin?

  Yeah, so then the question we start to ask is, what if the universe is a kind of spacetime origami? When it's created in the Big Bang, that all the dimensions are wrapped up, and maybe in very complicated ways, like the dimension of the straw being wrapped up. But one dimension just gets very, very big, or in our case, three.

• 9:05Neil deGrasse Tyson?

  Three with three big dimensions.

• 9:07Janna Levin?

  We have three big dimensions. We have time, which is a fourth, so we know there's up, down, north, south, east, west. That's it. You specify those things, and you definitely know where you are in space. You specify time, and we can actually meet. Right, here we are. But those extra directions just maybe didn't ever expand. And so, one of the things even that I'll work on, and string theorists will work on, people, is, why would only three dimensions get large if those other dimensions exist?

• 9:36Chuck Nice?

  Interesting.

• 9:37Janna Levin?

  Mm-hmm. So it could be that we'll understand the large connectedness, finite nature of space, by looking in like really high-energy accelerator experiments. Because people have asked at the Large Hadron Collider, could you perceive these extra dimensions if they exist?

• 9:56Chuck Nice?

  Okay. Wow, that, that, I gotta tell you.

• 9:59Neil deGrasse Tyson?

  Okay.

• 9:59Chuck Nice?

  Chris?

• 10:00Neil deGrasse Tyson?

  Are we done with the show?

• 10:02Chuck Nice?

  And people will be-

• 10:03Neil deGrasse Tyson?

  That's an entire show's worth of-

• 10:04Chuck Nice?

  We'll be back next week. We're just gonna let you think about that.

• 10:07Neil deGrasse Tyson?

  It's a week's worth of mind-blowing.

• 10:09Chuck Nice?

  That is-

• 10:10Janna Levin?

  That is a big start.

• 10:12Chuck Nice?

  That was a big start.

• 10:12Janna Levin?

  To cosmic queries.

• 10:13Chuck Nice?

  Wow, man, that's fascinating stuff, just fascinating. All right, let's move on to Paul Love, who says, given that-

• 10:19Neil deGrasse Tyson?

  Is that because you can pronounce his name, that's why we're going to him next?

• 10:21Chuck Nice?

  Let me tell you something. As a matter of fact, I think I'm just gonna call everybody Paul Love.

• 10:25Neil deGrasse Tyson?

  That's a beautiful name.

• 10:26Chuck Nice?

  Exactly. Paul says this. Given that our universe expanded from a single point and is expanding in all directions, how does that not define the shape of the universe as spherical? How could something flat or saddle-shaped come out of that?

• 10:49Janna Levin?

  Well, it is true, if there is an explosion in space, it tends to have a kind of spherical cloud leftovers debris. So when a star explodes, we will see often nebula and they're like often spherical-ish. Beautiful too, beautiful nebula. Very beautiful and you know, sometimes they plow into stuff and it changes the shape. But basically, yeah, then you can point inside this debris, point to where the center of the explosion was. So that's not how it works for the big bang. So for the big bang, you cannot imagine that the space exists first and that you're exploding into the space. It is actually a creation of the space itself.

• 11:32Janna Levin?

  Right, so everywhere in the universe was once at the center of the explosion. There is no plowing out, it's as though, and you can think of it any shape you want. Make some crazy, you know, people like the balloon analogy. So now make some crazy balloon, twisted up crazy thing and. A poodle. A poodle. Oh, nice. A balloon poodle universe and the whole thing stretches and the whole thing was once a point. So every single point on that surface and people get tripped up. It's part of that fabric, if you want to call it.

• 12:05Neil deGrasse Tyson?

  So the center is everywhere.

• 12:06Janna Levin?

  The center is everywhere. We are at the center of the big bang, as is every other point in space. It's at the center of the big bang.

• 12:13Neil deGrasse Tyson?

  But can I say, can I say that differently? Will you allow me to say differently? Can I say there is a center? The only way you can access it is to go back in time to the beginning of time.

• 12:25Janna Levin?

  Well, you could say. Ooh, okay. Oh, man, talk about dimensions.

• 12:31Neil deGrasse Tyson?

  So you can access the center of all of this only at one point in this coordinate system. And it's at t equals zero.

• 12:39Janna Levin?

  Mm-hmm. I would say.

• 12:40Neil deGrasse Tyson?

  And it's there, if timeline is just always there, there's the center.

• 12:44Janna Levin?

  Yeah, if we're going to be really, you know, split space up in very fine-grained terms. This point was at the center back at t equals zero and this point was at the center back at t equals zero. They just were all closer together. So the whole. So it's just the collapse.

• 12:58Chuck Nice?

  Of those points at T equals zero.

• 13:01Janna Levin?

  Yeah.

• 13:02Chuck Nice?

  Gotcha.

• 13:02Janna Levin?

  Yeah.

• 13:02Chuck Nice?

  But I like what you said, though, which I think is what people have to really think is. The space itself was created.

• 13:11Neil deGrasse Tyson?

  Yes.

• 13:11Chuck Nice?

  At the second, not second, the millisecond, microsecond, whatever, nanosecond.

• 13:17Neil deGrasse Tyson?

  A bajillionth of a second.

• 13:18Chuck Nice?

  A bajillionth of a second.

• 13:20Neil deGrasse Tyson?

  That's an official fraction, isn't it?

• 13:21Chuck Nice?

  Right. The bajillionth of a second afterwards. That's, that space was created then along with everything else.

• 13:29Janna Levin?

  I think that's like 10 to the minus 43 seconds.

• 13:31Neil deGrasse Tyson?

  Yeah, that's right.

• 13:32Janna Levin?

  Which would be a trillion, trillion, trillion, trillion-ish.

• 13:34Chuck Nice?

  There you go. So, you know, right then, so that, I mean, if you think of it that way, because what, what you're thinking about is these distances between these stuff that we see.

• 13:47Janna Levin?

  Yeah.

• 13:48Chuck Nice?

  And we think they're empty, but they came from that thing.

• 13:53Janna Levin?

  Yeah, from the Big Bang.

• 13:54Chuck Nice?

  From the Big Bang.

• 13:55Janna Levin?

  Yeah. So, so another, a reason why people get tripped up.

• 14:00Neil deGrasse Tyson?

  Chuck just blew a gas.

• 14:01Chuck Nice?

  I know, man.

• 14:04Chuck Nice?

  So crazy.

• 14:05Neil deGrasse Tyson?

  We just lost Chuck.

• 14:05Chuck Nice?

  I love it.

• 14:06Janna Levin?

  I would love if there was an actual steam effect.

• 14:10Neil deGrasse Tyson?

  Out of the ears?

• 14:10Janna Levin?

  Yeah.

• 14:12Chuck Nice?

  Wow. So, yeah, wow, go ahead.

• 14:15Janna Levin?

  So, here's where people get tripped up with the balloon analogy, because it's flawed, as are all analogies, is that a lot of people immediately want to point to the center of the balloon, the empty space inside. But you gotta give up on that. All that exists is the skin of the balloon.

• 14:28Chuck Nice?

  Right, right.

• 14:29Janna Levin?

  That is all that exists.

• 14:29Neil deGrasse Tyson?

  I'm okay with the center of the balloon, because that's where the balloon was at T equals zero.

• 14:33Janna Levin?

  Right, so you could think of it, good, I can only consider the center of the balloon as snapshots, like movie frames.

• 14:39Chuck Nice?

  Right.

• 14:40Janna Levin?

  So, it once was there, and then it was a movie frame over here, and then it's over there.

• 14:44Chuck Nice?

  But the center of that same balloon is still now at the outer reaches of the balloon, because it came from the center of the balloon.

• 14:51Janna Levin?

  Right, so imagine, imagine you painted dots all over the little infinitesimally small balloon. And they were glued to, you know, they're stains on the skin of the balloon. The dots themselves don't move. And then you push all that down, so all the dots are together, and then you pull them apart. In some sense, those are the galaxies that came later. The galaxies aren't moving.

• 15:08Chuck Nice?

  Right.

• 15:09Janna Levin?

  The stain on the balloon doesn't move. It's the, the skin, the stretching between the spots. So, in fact, nothing piles up the way it does when a supernova explodes. Everything actually just gets more and more diffuse as the universe expands.

• 15:24Chuck Nice?

  Crap.

• 15:25Neil deGrasse Tyson?

  Chuck, Chuck.

• 15:27Janna Levin?

  I know, it's some good stuff.

• 15:29Chuck Nice?

  This stuff is so, so like.

• 15:31Neil deGrasse Tyson?

  All right, next question.

• 15:32Chuck Nice?

  Wild, man. All right, that was, that was great. Thanks, Paul. All right, here we go. Let's go to Brendan Rico Suave. You just screw with me, Brendan. Okay. Brendan wants to know this.

• 15:47Chuck Nice?

  I've recently heard of a new study that states the universe is thought to be in the shape of a loop. Whereas previously it was thought to be flat. But in the explanation given, the nature of the loop shape states that it travels far enough in one direction that you'll end up back where you started, which is what we talked about earlier. My question is, wouldn't this happen regardless of actual shapes of the universe? So his point is like, no matter what you shape, would that happen?

• 16:19Janna Levin?

  Yeah, and I think that you can say.

• 16:22Neil deGrasse Tyson?

  I think that we have to take a break.

• 16:26Chuck Nice?

  Wow.

• 16:26Janna Levin?

  I should have seen that at the corner of my eye.

• 16:29Neil deGrasse Tyson?

  When we come back, Jan Levin is gonna tell us, do we live in a loop universe or not on StarTalk?

• 16:53Neil deGrasse Tyson?

  We're back. Cosmic Queries, StarTalk. Chuck Nice, my co-host.

• 16:57Chuck Nice?

  Thank you.

• 16:57Neil deGrasse Tyson?

  All right. Jan Levin, friend, colleague up at Barnard in Columbia. Doing that physics thing, cosmology.

• 17:04Janna Levin?

  Someone's gotta do it.

• 17:05Neil deGrasse Tyson?

  Somebody's gotta blow people's cosmological minds. So, so tell us, as the question had asked.

• 17:16Neil deGrasse Tyson?

  Do, would the universe loop back on itself no matter its shape?

• 17:20Janna Levin?

  Um, so, not necessarily.

• 17:23Neil deGrasse Tyson?

  How do you know what shape the universe is in the first place?

• 17:25Janna Levin?

  Yeah, it's really, we don't ultimately know the shape. We know that we can see the distance light has been able to travel since the Big Bang, because we can't see anything faster than the limit of the speed of light travel time. And, um, and we know that the universe is expanding, so that's actually 92 billion light years across about, that we can, that's what we call the observable universe. Now, it's possible that it's not 92 billion light years across, that even within that range, that the universe has folded back onto itself in some way, and we're actually seeing repeats of things. We're starting to see, it's kind of like a hall of mirrors thing, we're starting to see the light multiple times.

• 18:01Neil deGrasse Tyson?

  How would you know?

• 18:01Chuck Nice?

  Yeah, I was gonna say, how do you figure that out?

• 18:03Janna Levin?

  It is very, very hard to figure out. So there have been extremely clever ideas, and most of them are my-

• 18:08Neil deGrasse Tyson?

  If I get my telescope to look out and I see Chuck waving at me?

• 18:10Janna Levin?

  Yeah, right, exactly. Right, when he was a little baby, yeah.

• 18:16Neil deGrasse Tyson?

  You hear the one about the, right, okay.

• 18:18Janna Levin?

  So, it's true, we're looking at ourselves in the past, which is very hard to distinguish. If, for instance, if we're looking at galaxies, that's very hard to do, but there are patterns in the hot and cold spots left over from the Big Bang, if it fits into a specific shape. So imagine something just totally platonically beautiful and crazy, that the universe is like a dodecahedron, all of whose faces are glued together. So it's a crazy origami. That thing is, I mean, there has so many loops and-

• 18:41Neil deGrasse Tyson?

  Dodecahedrons, 20-sided, big triangles.

• 18:44Janna Levin?

  Right, and that is conceivable, kind of what we call topology, or connectedness of the space. There, it would actually start to imprint that, the, the patterns of the dodecahedron in the light left over from the Big Bang. So if you imagine there's tiny little hot and cold spots, that you would start to see in the distribution of the hot and cold spots.

• 19:06Neil deGrasse Tyson?

  That shape.

• 19:06Janna Levin?

  That shape would be reflected in, in a very subtle way.

• 19:10Neil deGrasse Tyson?

  Really?

• 19:10Janna Levin?

  Yeah, so, the reason, the-

• 19:13Neil deGrasse Tyson?

  You don't mean reflected literally, you mean manifested?

• 19:15Janna Levin?

  Manifested, so, uh, so how the leopard got its spots is actually a very similar mathematical problem, because you're asking about enzymes being high or low in the developing embryo, and it turns out that the shape and the size of the animal- And like whether it's tubular or when those spots are hitting it that it will determine what kind of spots the animal gets.

• 19:34Neil deGrasse Tyson?

  In an actual leopard.

• 19:35Janna Levin?

  In an actual leopard, zebra, stripes, like these things are things you can predict by solving for the mathematics of of things that are above a certain threshold or below a certain threshold that that pattern of stripes or spots will reflect the geometry.

• 19:48Neil deGrasse Tyson?

  And the black panther is a leopard, you knew that.

• 19:50Chuck Nice?

  Yes, I did know that.

• 19:51Neil deGrasse Tyson?

  And the black panther has spots.

• 19:52Chuck Nice?

  Now, that I didn't know.

• 19:53Janna Levin?

  On its skin?

• 19:54Neil deGrasse Tyson?

  It has spots.

• 19:55Chuck Nice?

  On its skin.

• 19:55Neil deGrasse Tyson?

  If you look very carefully, you can see the spots.

• 19:57Janna Levin?

  Oh, wow, amazing. Well, so so how the universe got its spots is a similar mathematical problem. We're solving for hot and cold spots in a particular geometry when the universe was like a developing embryo, basically. And this goes back to Alan Turing, who's who who solved some of these problems for the animal.

• 20:12Chuck Nice?

  But like a black panther, does the universe care about injustices to the black man?

• 20:16Janna Levin?

  Apparently not, Chuck. Apparently not. I mean, if this is any evidence, if this planet is any evidence.

• 20:26Neil deGrasse Tyson?

  Just to bring that into modern reference. Or does the universe have vibranium?

• 20:30Chuck Nice?

  There you go.

• 20:33Neil deGrasse Tyson?

  I'm just saying.

• 20:35Janna Levin?

  Well, well, you know, we can hope that we're the bad example, and that elsewhere in the universe there are better examples.

• 20:42Chuck Nice?

  Nice. Well, well, well said, well said.

• 20:44Neil deGrasse Tyson?

  All right, Chuck, what else you got?

• 20:45Chuck Nice?

  All right, here we go. This is Tim Braid, who wants to know this. A very recent study in the Astrophysical Journal found that galaxies may be rotating in sync with other galaxies millions of light years away. Galaxies separated by six megaparsecs were found directly interacting with each other. What is your opinion on this? First of all, is that empirical, that the fact that these galaxies were actually interacting with one another?

• 21:15Janna Levin?

  I think that that study is probably still controversial and probably still requires other.

• 21:20Neil deGrasse Tyson?

  Which means probably wrong.

• 21:23Neil deGrasse Tyson?

  I'll be your translator.

• 21:25Janna Levin?

  I can't say like-

• 21:26Neil deGrasse Tyson?

  That's an interesting study. Probably wrong. It's probably wrong.

• 21:31Janna Levin?

  I mean, these things can happen, but it just sounds not that likely. And so there will be a lot of people doing observations in different wavebands with different perspectives to try to break any possibility that it's a quirk of this particular, you know, observation. But six megaparsecs, you know, that's pretty far away.

• 21:48Neil deGrasse Tyson?

  Yeah.

• 21:48Janna Levin?

  And so you would think that you would be dominated there by the expansion of the universe and not interactions. We definitely interact with other galaxies. That's not a big surprise.

• 21:57Neil deGrasse Tyson?

  Just in nearby ones, yeah.

• 21:59Janna Levin?

  Yeah, Andromeda's, we're falling, we're gonna collide with Andromeda. That's a happy future. Like, imagine when Andromeda gets much closer, how cool the night sky is gonna be. Hey, girl! It's gonna be like right there, you're gonna like see a whole galaxy.

• 22:11Neil deGrasse Tyson?

  No, no, actually, it won't be as cool as you think. I'll tell you at the end of your answer, though. It's not gonna be as cool as you think.

• 22:15Janna Levin?

  Cause it's, is it coming in edge on?

• 22:17Neil deGrasse Tyson?

  No, no, no, I'll tell you why in a minute. It's a very, it's a disturbing reason why it's not gonna be cool.

• 22:23Chuck Nice?

  So now, speaking of edge on, now you just, I'm sorry, cause I'm a little all over the place, but I gotta get this in before we move on.

• 22:29Janna Levin?

  Yeah.

• 22:30Chuck Nice?

  So, speaking of edge on, so if you're looking at something edge on, how do we flip it to get the imagery to know that we were looking at the disk from the edge?

• 22:39Janna Levin?

  So we do that with our own Milky Way. We're in the Milky Way, so we're seeing the rest of the galaxy edge on.

• 22:45Chuck Nice?

  Right.

• 22:45Janna Levin?

  We've never seen the Milky Way as human beings from above. But we have these beautiful constructions because we just map things as accurately as we understand where they are also in space.

• 22:55Chuck Nice?

  Okay.

• 22:55Janna Levin?

  So we just, we build an atlas of it, basically. You build a numerical model based on all of your observations of the Milky Way, the gas, the dust, the stars, everything, where the spirals are, where the gaps are, and then you just allow yourself to move in that digital world and look down from above. But it's an experiment, it's a numerical experiment.

• 23:14Neil deGrasse Tyson?

  So it's the modern version of map making?

• 23:15Chuck Nice?

  Right.

• 23:16Neil deGrasse Tyson?

  Because you're not making it in three dimensions.

• 23:17Chuck Nice?

  Exactly.

• 23:17Neil deGrasse Tyson?

  And once you have a, once you have a map, you can go anywhere you want. And a three-dimensional map, you go anywhere.

• 23:21Janna Levin?

  Yeah, you can-

• 23:22Neil deGrasse Tyson?

  And plus...

• 23:24Neil deGrasse Tyson?

  We see all the gas and we're quite flattened in the sky.

• 23:27Janna Levin?

  Mm-hmm.

• 23:27Neil deGrasse Tyson?

  And there are other galaxies out there that are flattened. And we can see them at all, not one galaxy at different angles, but a million galaxies all scattered in random angles.

• 23:37Chuck Nice?

  Right.

• 23:38Neil deGrasse Tyson?

  And so it's pretty easy to figure out what we look like.

• 23:40Janna Levin?

  Mm-hmm.

• 23:41Neil deGrasse Tyson?

  By looking at others.

• 23:42Chuck Nice?

  By looking at us.

• 23:42Neil deGrasse Tyson?

  Adding and adding.

• 23:43Janna Levin?

  Yeah. And that's what we look like until we collide with Andromeda. But one of the things I took solace in, but I feel like Neil's about to make me very uncomfortable.

• 23:49Neil deGrasse Tyson?

  No, I have to, I'm sorry.

• 23:50Janna Levin?

  But the whole solar system's supposed to stay together, right? And get knocked around?

• 23:53Neil deGrasse Tyson?

  We should stay together.

• 23:54Janna Levin?

  So we might end up in Andromeda before we fully collide. Like, they could pass each other. They could collide, move through each other, and we could end up in Andromeda, looking at the Milky Way.

• 24:03Chuck Nice?

  And that distinction. Milky Way, we're gonna leave a forward in a dress.

• 24:07Neil deGrasse Tyson?

  But what will, so what'll happen is there'll be a lot of sort of dissipated energy. And the sys, well, they'll of course pass through each other and back and forth. We've done this on a computer.

• 24:16Janna Levin?

  Mm-hmm.

• 24:17Neil deGrasse Tyson?

  And it's, it's like a rubber band kind of thing, and it kind of dies down. And it settles into one double large massive system.

• 24:24Janna Levin?

  Okay, so what's the bad news?

• 24:25Neil deGrasse Tyson?

  Okay. So, I hate to break the news to you.

• 24:27Janna Levin?

  That sounds like good news to me.

• 24:28Neil deGrasse Tyson?

  Okay. So, if Andromeda were 100 times closer, it wouldn't be any brighter on the sky.

• 24:36Janna Levin?

  Hmm, interesting.

• 24:38Neil deGrasse Tyson?

  Yeah.

• 24:38Chuck Nice?

  Okay, I'm, I'm, you've lost. Yeah, you totally lost me there.

• 24:42Neil deGrasse Tyson?

  I'll tell you why, okay?

• 24:43Janna Levin?

  Yeah, tell me why, it's not obvious.

• 24:45Neil deGrasse Tyson?

  Okay, I'm gonna tell you.

• 24:46Janna Levin?

  Yeah.

• 24:47Neil deGrasse Tyson?

  I'm gonna tell you?

• 24:47Chuck Nice?

  Okay.

• 24:48Neil deGrasse Tyson?

  Can I tell you?

• 24:48Janna Levin?

  Yeah.

• 24:49Neil deGrasse Tyson?

  All right, so Andromeda has a certain size on the sky, correct?

• 24:53Chuck Nice?

  Right.

• 24:53Neil deGrasse Tyson?

  Okay, it has a certain extent.

• 24:54Janna Levin?

  Mm-hmm.

• 24:55Neil deGrasse Tyson?

  And on a very dark night, not in the city, but where the moon is not out, you can see this fuzzy thing in the sky, so that's in the Andromeda Galaxy. It's 2 million light-years away.

• 25:06Chuck Nice?

  Mm-hmm.

• 25:07Neil deGrasse Tyson?

  All right. There's a certain amount of light coming from Andromeda in that patch on the sky.

• 25:14Chuck Nice?

  Right.

• 25:14Neil deGrasse Tyson?

  So, we, we reference it's, something called a surface brightness. It is, how bright is Andromeda over that patch of sky? Over that surface patch on the sky? Surface brightness, okay? If we bring it... Half as far away. Okay. Make it only half as far. It is how many times brighter?

• 25:39Janna Levin?

  It should go like the square.

• 25:41Neil deGrasse Tyson?

  Like the square.

• 25:41Janna Levin?

  But then the area is also going.

• 25:43Neil deGrasse Tyson?

  It'll be four times brighter.

• 25:44Janna Levin?

  But the area is gonna go like that square.

• 25:45Neil deGrasse Tyson?

  By a factor of four.

• 25:47Janna Levin?

  Yeah. So.

• 25:48Neil deGrasse Tyson?

  So, so the whole system is getting brighter. But the surface area is remaining the same.

• 25:54Janna Levin?

  Right.

• 25:55Neil deGrasse Tyson?

  So it is not gonna be more apparent to you in the night sky than our own Milky Way is on our own night sky. I'm very sad to report that. I'm just sad.

• 26:07Janna Levin?

  But it'll look cool.

• 26:08Chuck Nice?

  It'll look cool.

• 26:09Neil deGrasse Tyson?

  No, it'll just still be fuzzy. Can I see? You gotta get out of the city, get rid of the full moon. Now I see the colliding galaxy.

• 26:16Janna Levin?

  Right.

• 26:16Neil deGrasse Tyson?

  No, sorry. I'm very sorry about this.

• 26:19Janna Levin?

  Okay.

• 26:20Neil deGrasse Tyson?

  Jana, I'm sorry to report this.

• 26:21Janna Levin?

  That's right. I'm, I'm, you know.

• 26:23Neil deGrasse Tyson?

  It'll just look like our own Milky Way galaxy.

• 26:25Janna Levin?

  Mm-hmm. Yeah.

• 26:26Neil deGrasse Tyson?

  If Andromeda were right here next to us, it would just look like our Milky Way in the night sky. Which you cannot see from New York City.

• 26:31Janna Levin?

  Which you cannot see from New York City. It is true. But you can see with one of those apps, like you can just. You know, you can hold it. It could be like.

• 26:39Neil deGrasse Tyson?

  Hold up your smartphone.

• 26:40Janna Levin?

  And it could be like down there and it'll show you like a beautiful.

• 26:43Neil deGrasse Tyson?

  Show you Andromeda on its way. And you pump up the count, the, the intensity.

• 26:46Janna Levin?

  Who needs eyes?

• 26:50Janna Levin?

  That's overrated.

• 26:52Neil deGrasse Tyson?

  It is true. We are practically blind.

• 26:54Chuck Nice?

  This is the new model for astronomy.

• 26:56Janna Levin?

  Yeah.

• 26:57Neil deGrasse Tyson?

  Who needs eyes?

• 26:58Janna Levin?

  We're, we're becoming cyborgish, you know?

• 27:00Neil deGrasse Tyson?

  She is so right on this. Chuck.

• 27:02Janna Levin?

  Yeah.

• 27:02Neil deGrasse Tyson?

  Chuck, we've.

• 27:03Janna Levin?

  Cool glasses.

• 27:04Neil deGrasse Tyson?

  As, as the centuries went on, we discovered how blind we actually were.

• 27:08Janna Levin?

  Yeah, that's amazing.

• 27:09Neil deGrasse Tyson?

  Yeah.

• 27:10Chuck Nice?

  All right, there we go. Okay, let's move on to David.

• 27:14Neil deGrasse Tyson?

  Oh, by the way, those Hubble photos?

• 27:16Chuck Nice?

  Yes.

• 27:17Neil deGrasse Tyson?

  If you go to those objects, you don't see what the Hubble saw. Because the Hubble sees better than you do.

• 27:22Janna Levin?

  A lot better.

• 27:22Neil deGrasse Tyson?

  A lot better.

• 27:24Janna Levin?

  I mean, if you could just like stare at it for 10 days.

• 27:27Neil deGrasse Tyson?

  Or if your eyeballs were like, like.

• 27:29Chuck Nice?

  Gargantuan?

• 27:30Neil deGrasse Tyson?

  Gargantuan, then it'll look like what the Hubble sees.

• 27:32Janna Levin?

  Yeah.

• 27:33Neil deGrasse Tyson?

  All right.

• 27:33Chuck Nice?

  Cool. All right, uh, this is David Eduardo Perales Martinez, who wants to know.

• 27:39Neil deGrasse Tyson?

  Oh, you did good there.

• 27:40Chuck Nice?

  Yeah, well, not bad, you know. My wife. My wife is Puerto Rican.

• 27:45Neil deGrasse Tyson?

  Let me hear that again. Go.

• 27:46Chuck Nice?

  David, or would, or would be David Eduardo Perales Martinez.

• 27:50Neil deGrasse Tyson?

  Martinez.

• 27:51Chuck Nice?

  Yes. Uh, who says this? Um, why is it so hard to prove the existence of other dimensions?

• 28:00Chuck Nice?

  Thank you, David from Mexico.

• 28:02Janna Levin?

  Yeah.

• 28:03Chuck Nice?

  Or Mexico.

• 28:04Janna Levin?

  Um, so.

• 28:04Neil deGrasse Tyson?

  I want to ask that a slightly different way.

• 28:06Janna Levin?

  Yeah.

• 28:06Chuck Nice?

  Go ahead.

• 28:07Neil deGrasse Tyson?

  If there was another dimension as big as the three that we're in.

• 28:10Janna Levin?

  Mm-hmm.

• 28:10Neil deGrasse Tyson?

  Would it completely manifest to us?

• 28:13Janna Levin?

  Probably, there's a hitch. So you would think, yes, as long as that dimension was very large, then we would be talking about a world in which this did not confine us, right? So, so, so let's say I have skin, which seems to separate my inside and my outside. But if there was another.

• 28:29Neil deGrasse Tyson?

  I can see right inside you.

• 28:30Janna Levin?

  If, right, if there was another dimension, you could do like one of those spooky surgeries without.

• 28:34Neil deGrasse Tyson?

  Yeah.

• 28:35Janna Levin?

  Puncturing any skin, you could just like go in there and touch people's organs. Like, this would not be a separation of inside and outside.

• 28:40Neil deGrasse Tyson?

  Well, there's also an analogy to that is if you're only live in two dimensions, then you only have sort of height and width, uh, heightened, you have height and width, but not depth.

• 28:53Janna Levin?

  Mm-hmm.

• 28:53Neil deGrasse Tyson?

  So if you don't have depth, when I, if I look at you in two dimensions, I can see all your organs.

• 28:57Janna Levin?

  Mm-hmm.

• 28:58Neil deGrasse Tyson?

  All of them.

• 28:58Janna Levin?

  For you, for your skin would be a line.

• 29:00Neil deGrasse Tyson?

  Spleen, whatever.

• 29:01Chuck Nice?

  Operation.

• 29:02Neil deGrasse Tyson?

  You, operation.

• 29:03Janna Levin?

  Yeah, it's a great game.

• 29:03Neil deGrasse Tyson?

  You can't see because you're in the, and all you see is the outer skin, which is just a line.

• 29:08Janna Levin?

  Which is just a line.

• 29:09Neil deGrasse Tyson?

  Yeah, and now our outer skin is a surface.

• 29:12Janna Levin?

  Right.

• 29:12Neil deGrasse Tyson?

  Right.

• 29:12Janna Levin?

  So which is why, you know, you can't actually probably have a very effective organism in just two dimensions, because let's say they had a mouth and a tube going all the way through them, it would actually cut the two sides in half.

• 29:27Neil deGrasse Tyson?

  Yeah.

• 29:28Janna Levin?

  So you can't have what we consider to be normal metabolic functions of, okay, anyway.

• 29:32Neil deGrasse Tyson?

  You know what else you, you don't have? You don't have porosity in two dimensions.

• 29:35Janna Levin?

  Yeah, you can't have porosity.

• 29:36Neil deGrasse Tyson?

  Oh, uh, so if you drop water on soil and then it just soaks in.

• 29:40Chuck Nice?

  Right.

• 29:41Neil deGrasse Tyson?

  Or you're dropping on a sponge and it soaks in.

• 29:42Chuck Nice?

  Okay.

• 29:43Neil deGrasse Tyson?

  In two dimensions, there's no such thing as, like.

• 29:46Chuck Nice?

  No soaking.

• 29:47Neil deGrasse Tyson?

  There's no soaking.

• 29:47Chuck Nice?

  No soaking in.

• 29:48Neil deGrasse Tyson?

  Right.

• 29:48Chuck Nice?

  So you just have a bulb of water.

• 29:50Neil deGrasse Tyson?

  A bulb of water, correct.

• 29:51Chuck Nice?

  Sitting on top of it.

• 29:52Neil deGrasse Tyson?

  Because porosity enables, um, you have two, let's say two rocks are touching here.

• 29:57Chuck Nice?

  Mm-hmm.

• 29:58Neil deGrasse Tyson?

  But then the water can just go around another side of the rock.

• 30:00Chuck Nice?

  Right.

• 30:01Janna Levin?

  Mm-hmm.

• 30:01Neil deGrasse Tyson?

  But in two dimensions where they touch, there is no way past it.

• 30:04Chuck Nice?

  Right.

• 30:05Neil deGrasse Tyson?

  It will just stay above it.

• 30:06Chuck Nice?

  Is that where you're able to smell what the rock is cooking? Okay.

• 30:09Janna Levin?

  Like.

• 30:10Neil deGrasse Tyson?

  No, I'm not.

• 30:11Janna Levin?

  We're like, we're like.

• 30:13Chuck Nice?

  That was, don't worry.

• 30:15Janna Levin?

  So here, I will tell you this. Some people argue that the reason why the universe is three-dimensional is because the universe tries to be many different ways. There may have been an infinite number of big bangs in the past and the future. You can't really talk about it in temporal relativity. But if the universe created a two-dimensionally-large universe with all the rest rolled up and small, you couldn't have organisms in that universe to ask the questions.

• 30:38Neil deGrasse Tyson?

  Wow.

• 30:39Janna Levin?

  So you'd need at least three. And then let's say you had four spatial dimensions. Then you have the problem of things drift away from each other in such a way that it's hard to have organized systems. So just like Neil was describing, a two-dimensional creature isn't aware of the third dimension. But if they became aware, they could just kind of float away from their city, right? It becomes... You have more volume of space to fill.

• 31:01Neil deGrasse Tyson?

  Mm-hmm.

• 31:02Janna Levin?

  And the cross-section for interaction goes down. So now if you add another dimension, the cross-section for interaction goes down again.

• 31:09Neil deGrasse Tyson?

  No, but we successfully exist in three dimensions in spite of the challenges the two-dimensional creature would face upon accessing a third dimension.

• 31:18Janna Levin?

  Right.

• 31:18Neil deGrasse Tyson?

  So why...

• 31:19Janna Levin?

  Maybe three is optimal.

• 31:21Neil deGrasse Tyson?

  Why don't four-dimensional creatures pity us?

• 31:23Janna Levin?

  Yeah.

• 31:25Janna Levin?

  Right, well, that is a good question. Could the complexity... Like, I'm not saying they're true arguments, but some people argue that you couldn't, in the four dimensions, get the successful complexity. And some of those arguments are... They get, you know, complicated based on string theory, cross-sections and annihilations into photons, and what's left over after all of these things in the big bang. It turns out that only a tiny, tiny bit of stable matter is left over already in three dimensions from the big bang.

• 31:51Neil deGrasse Tyson?

  So it could be... Wait a minute. Let me kind of agree with what you just said, even though I just disagreed. What you're saying is, in three dimensions, it could be optimal for particles to get together and make molecules, and molecules to make macroscopic objects. If you add a fourth dimension... You're adding a degree of freedom of where things can hang out. And possibly never then find each other.

• 32:18Janna Levin?

  Yeah.

• 32:18Neil deGrasse Tyson?

  Ever again.

• 32:19Janna Levin?

  If you think about the volume of the universe is going up radically with the volume of dimensions.

• 32:24Neil deGrasse Tyson?

  Yes.

• 32:24Janna Levin?

  Then you're diluting everything in the universe significantly.

• 32:27Neil deGrasse Tyson?

  The concentration of what could be.

• 32:28Chuck Nice?

  Ooh.

• 32:29Janna Levin?

  But there's any...

• 32:30Neil deGrasse Tyson?

  So the fact that you're even asking that question means you are a being in an optimized universe. To even pose the question in the first place.

• 32:39Chuck Nice?

  So the two dimensional people couldn't ask this question?

• 32:42Janna Levin?

  Right, because they couldn't be two dimensional people. Because the structures are too simple to allow.

• 32:47Neil deGrasse Tyson?

  And four dimensional people, there's too much, too much place space.

• 32:51Janna Levin?

  So let's take, let's take, your first question was, would we know it if the other dimensions were large? Here's the hitch, you would think we would, but here's the hitch. Even if all of those problems were solvable. There is an argument that we could be glued to a kind of a membrane. Which is a three dimensional surface floating in this higher dimensional space.

• 33:13Neil deGrasse Tyson?

  And what glues us there?

• 33:14Janna Levin?

  It's the...

• 33:15Chuck Nice?

  Elmers.

• 33:16Janna Levin?

  The Elmers. The way the fundamental forces work between...

• 33:22Neil deGrasse Tyson?

  They keep us there.

• 33:22Janna Levin?

  They keep us on the membrane. And the only thing that happily goes off the membrane is, is gravity itself.

• 33:28Neil deGrasse Tyson?

  Right.

• 33:28Janna Levin?

  So that all other forces are glued to this membrane. That's where they live. So that you would think like a particle to you, interacting with that membrane, could be a string in the higher dimensional space.

• 33:39Neil deGrasse Tyson?

  Passing through your space, manifesting as a particle.

• 33:42Janna Levin?

  Manifesting as a particle. So like imagine cutting a string, you would, it would look to you like a dot.

• 33:47Neil deGrasse Tyson?

  Right.

• 33:48Janna Levin?

  An infinitely thin string.

• 33:49Neil deGrasse Tyson?

  And that is wild. The way I think about in two dimensions, I think of passing a hollow sphere through two dimensions. What would that look like to the two dimensional people? They'd see a dot, and say, well, that's cool. Oh, then it becomes like a circle. And it gets bigger and bigger and bigger. Then it maximizes out at the diameter, but they don't know this. And then it gets smaller, then it gets a point and disappears.

• 34:11Chuck Nice?

  And they have no idea that a big sphere just passed through their whole existence.

• 34:15Neil deGrasse Tyson?

  Mystical, magical hypotheses come out. And the scientists analyze it. We just say stuff pops in and out of existence, we don't know why.

• 34:22Janna Levin?

  So one of the, yeah, absolutely. So one of the things that we've worked on with extra dimensions that make them not just an oddity, but maybe something we've already observed.

• 34:30Neil deGrasse Tyson?

  One of the things we've worked on, on our extra dimensions. This is, this, Janet, what's in your basement? She's a superhero nemesis character in the making.

• 34:40Janna Levin?

  My superhero character name is Jan 11.

• 34:45Janna Levin?

  Isn't it good? And it's a prime number.

• 34:48Chuck Nice?

  Jan 11.

• 34:48Janna Levin?

  I mean, I've gotta work that somehow.

• 34:50Neil deGrasse Tyson?

  You don't want to be the superhero. You want to be the nemesis. That's way more fun. Because he could be diabolical with the science. That's Jan 12.

• 35:00Janna Levin?

  My evil twin, Jan 12. So, um, so the interesting thing there that we're, people have thought about is that maybe something like dark energy is actually a quantum phenomenon. Trapped in the extra dimensions that we can't perceive the extra dimensions directly, but we're indirectly perceiving them through the dark energy.

• 35:18Neil deGrasse Tyson?

  Or dark matter is regular matter in the higher dimensions leaking over.

• 35:22Chuck Nice?

  Into, right, through this membrane.

• 35:24Neil deGrasse Tyson?

  And we're just doing this, and it's just mysteriously there.

• 35:28Janna Levin?

  Yeah, we, people have definitely wondered if dark matter could have to do with the extra dimensions.

• 35:32Chuck Nice?

  Gravity is the thing that is the medium. Is that, is that the deal?

• 35:35Janna Levin?

  Gravity is spacetime, so gravity can't be confined to, otherwise there would be no meaning to the extra dimension.

• 35:42Neil deGrasse Tyson?

  Stupid.

• 35:46Chuck Nice?

  Everybody knows that. Mike, was that Chuck? That was your problem.

• 35:49Neil deGrasse Tyson?

  Chuck, we gotta take a quick break.

• 35:50Chuck Nice?

  Okay.

• 35:50Neil deGrasse Tyson?

  When we come back, more with Jan 11 on the edge of the universe and beyond when StarTalk returns.

• 36:05Chuck Nice?

  Hey, we'd like to give a Patreon shout out to the following Patreon patrons. Roy Hill Percival, Jose Clark, and Dr. Janet L. Walsh. Thanks so much, guys, for helping us make this little trip through the cosmos. And if you would like to support us on Patreon, go to patreon.com.

• 36:34Neil deGrasse Tyson?

  We're back. StarTalk, Cosmic Queries, the edge of the universe. There's only one person in arm's reach out there that who could do this. Janna Levin. Jana. She's our go-to person.

• 36:46Chuck Nice?

  Yes.

• 36:46Janna Levin?

  I love being the go-to person. It's the best.

• 36:49Neil deGrasse Tyson?

  Totally the best.

• 36:50Janna Levin?

  I have actually written papers on extra dimensions. It is a genuine

• 36:53Neil deGrasse Tyson?

  It's a thing.

• 36:54Janna Levin?

  direction in my, pardon the pun, in my research is to think about this.

• 36:57Neil deGrasse Tyson?

  So when she disappears?

• 36:59Chuck Nice?

  We'll know.

• 36:59Neil deGrasse Tyson?

  We'll know.

• 37:00Janna Levin?

  Wouldn't that just be so cool?

• 37:02Neil deGrasse Tyson?

  Yeah.

• 37:02Janna Levin?

  Monsters, I got up and then like went into the fourth dimension. And then my just would disappear.

• 37:07Neil deGrasse Tyson?

  This is how Monsters, Inc. worked.

• 37:08Janna Levin?

  Yeah.

• 37:09Neil deGrasse Tyson?

  Monsters, Inc. These are doors.

• 37:11Janna Levin?

  Yeah.

• 37:12Neil deGrasse Tyson?

  That came out of the factory.

• 37:13Chuck Nice?

  Right.

• 37:13Neil deGrasse Tyson?

  This was an uncelebrated fact of that movie. These are four-dimensional portals. They're basically wormholes.

• 37:20Janna Levin?

  They're amazing.

• 37:20Neil deGrasse Tyson?

  Each door, this is the door to the kid's room. And the monster takes it home at the end of the day. And they open the door, and the other side of the door is the kid's closet.

• 37:28Janna Levin?

  Right.

• 37:28Neil deGrasse Tyson?

  Okay?

• 37:29Janna Levin?

  So great.

• 37:29Neil deGrasse Tyson?

  And then they come out in the closet, scare the kid, go back through the door, and they're back at home.

• 37:33Janna Levin?

  It is a great movie.

• 37:34Neil deGrasse Tyson?

  Yeah, okay.

• 37:36Chuck Nice?

  I love it. All right. Let's, let's, let's go to, you know what? Let's go back to a Patreon patron. This is, uh, um, Solercero de Rai, okay, who says, "What do y'all think about the..." You like that?

• 37:52Neil deGrasse Tyson?

  I like it. Okay.

• 37:54Chuck Nice?

  "What do y'all think about the idea that matter consumed by black holes has been recycled and manifested back into the universe as dark energy?"

• 38:04Neil deGrasse Tyson?

  So matter coming out the other side, maybe?

• 38:05Chuck Nice?

  Right.

• 38:06Neil deGrasse Tyson?

  Okay.

• 38:06Chuck Nice?

  So is there any correlation between the matter consumed by black holes and dark energy? Um, could black holes and dark energy, dark matter, be different sides of the same coin?

• 38:17Janna Levin?

  Well, uh, I mean... Where to begin with this?

• 38:21Neil deGrasse Tyson?

  That's right, because there's a lot. I can lead off by saying, there's an urge to take everything you don't know, and assume it's related. Right. So I've got people talking about dark matter, consciousness, God, and dark energy, all as one thing.

• 38:36Janna Levin?

  Right.

• 38:36Neil deGrasse Tyson?

  And quantum spookiness.

• 38:39Janna Levin?

  Yes, someone asked me, when they take ayahuasca, is it possible that they have gone to a higher dimensional space?

• 38:45Neil deGrasse Tyson?

  Okay. Okay.

• 38:48Janna Levin?

  But my answer to, in an attempt to not be totally dismissive, was to say, well, if it's a platonic form that we can learn about by exploring the mind, then, in that sense, maybe.

• 38:59Neil deGrasse Tyson?

  Right.

• 38:59Janna Levin?

  Right? Like, a perfect circle doesn't exist in reality, nor will a perfect circle ever exist anywhere in the universe. But you can touch it in your mind, right?

• 39:06Neil deGrasse Tyson?

  Right.

• 39:06Janna Levin?

  And it's an experiment we can all perform, so that, in that sense, we go places.

• 39:11Neil deGrasse Tyson?

  Unlocking secrets in the mind, if not secrets of the physical universe itself.

• 39:15Janna Levin?

  Yes, yes.

• 39:16Neil deGrasse Tyson?

  In other words, you hide.

• 39:20Neil deGrasse Tyson?

  So what do you say about dark matter, dark energy?

• 39:23Janna Levin?

  So, okay, so let's just start with the falling in coming out. So there were, very early on, people who thought, a black hole could be bigger on the inside than the outside. It could be as big as an entire universe on the inside. It could actually lead to a white hole, which is basically a big bang. So you fall into the black hole, and that is completely confined by the event horizon, nothing ever comes out. But inside, it is like something as big as an entire universe.

• 39:51Neil deGrasse Tyson?

  Right.

• 39:52Janna Levin?

  Another universe. And that universe would remain like a TARDIS.

• 39:56Neil deGrasse Tyson?

  Yeah, bigger on the inside than the outside, right.

• 39:57Janna Levin?

  Exactly. It's just like Doctor Who's TARDIS. And so we would never know about that universe, it would not communicate with ours.

• 40:05Neil deGrasse Tyson?

  Check Chucks' street cred. TARDIS is an acronym for what? Oh, no. Oh, no. Phone booth in London?

• 40:18Neil deGrasse Tyson?

  Time.

• 40:21Neil deGrasse Tyson?

  Time and relative dimension in space.

• 40:24Chuck Nice?

  Time and relative dimension in space.

• 40:25Neil deGrasse Tyson?

  Hardest. There you go.

• 40:26Janna Levin?

  Usually the "and" doesn't make it into the acronym, I'm just gonna say. You know. Okay, so, so, so that was an interesting idea and a lot of people object to it because it in some subtle way suggests an unstableness to big bangs that might make it so that this world couldn't be stable if that were true. But honestly, it's not completely off the table. There's a lot, you could talk to some very important early relativists, they will still say that's what happens.

• 40:51Neil deGrasse Tyson?

  Relativists, an expert on relativity.

• 40:53Janna Levin?

  On relativity. So then there's a separate, totally separate question about dark matter. There is a suggestion that the black holes themselves could be dark matter, meaning that they are invisible, like dark matter is, technically, and, and they could populate the universe almost arguably large enough to explain this missing mass, this missing matter. It's on the edge, it's definitely under pressure.

• 41:20Neil deGrasse Tyson?

  Right, but there's a problem with like, big bang nucleosynthesis, if it's ordinary matter.

• 41:26Janna Levin?

  The black holes don't have to be made by collapsing stars out of ordinary matter, but you're absolutely right, we don't know how to make enough ordinary matter.

• 41:32Neil deGrasse Tyson?

  There's some issues.

• 41:33Janna Levin?

  Right, so they're not made from stars.

• 41:34Neil deGrasse Tyson?

  So, can I show you my black hole lunchbox?

• 41:36Janna Levin?

  Oh, let's do it.

• 41:37Neil deGrasse Tyson?

  Can I show you my...

• 41:38Janna Levin?

  I wanna know what's inside the lunchbox, but I can never find out, can I?

• 41:42Neil deGrasse Tyson?

  If you go in, she will never come out.

• 41:45Janna Levin?

  If my hand goes in, will it never come out? Ah! Exactly.

• 41:51Neil deGrasse Tyson?

  Okay.

• 41:52Chuck Nice?

  And inside of it is a black hole thermos, but of course.

• 41:55Janna Levin?

  It is confusing, if you fall into a black hole like this, I guess you can't see your hands. It's very confusing.

• 42:00Neil deGrasse Tyson?

  Oh yeah, yeah, you'll disappear in front of yourself.

• 42:03Janna Levin?

  Yeah.

• 42:04Neil deGrasse Tyson?

  Okay.

• 42:05Chuck Nice?

  So you have a black hole thermos and it is filled with...

• 42:07Neil deGrasse Tyson?

  Okay, so...

• 42:08Janna Levin?

  Liquor.

• 42:11Neil deGrasse Tyson?

  This is an inversion of the known universe, because in this particular case...

• 42:17Chuck Nice?

  Inside your black hole...

• 42:18Neil deGrasse Tyson?

  I have the Milky Way inside the black hole.

• 42:21Chuck Nice?

  No you did not.

• 42:22Janna Levin?

  He did that, yes.

• 42:23Chuck Nice?

  No you just did not do that.

• 42:24Janna Levin?

  He totally did that, sir.

• 42:25Chuck Nice?

  You did not just pull a Milky Way out of a black hole.

• 42:30Neil deGrasse Tyson?

  Because the black holes are always inside the Milky Way.

• 42:33Chuck Nice?

  I am just gonna say that that was the most committed joke I have ever seen in my life.

• 42:38Neil deGrasse Tyson?

  I'm just saying.

• 42:39Chuck Nice?

  For those of you who don't have a camera, I'm just telling you, Neil had an actual Milky Way candy bar inside of a black hole thermos, okay?

• 42:47Neil deGrasse Tyson?

  Inside my black hole lunchbox.

• 42:48Chuck Nice?

  Inside of his black hole lunchbox, okay?

• 42:52Neil deGrasse Tyson?

  You're just jealous, that's all.

• 42:55Chuck Nice?

  I'm a little jealous of the black hole lunchbox.

• 42:57Janna Levin?

  Definitely a little bit jealous. So, the last question, which is pretty hard, is could they all be connected? The stuff that falls in and comes out? And classically, we'd say no way. Vent horizon separates everything from the inside, the outside. But then there's like quantum entanglement across the Vent horizon. Maybe some particles on the inside are also the same thing as the particles on the outside. They're the same particles because of entanglement and wormholes and some crazy stuff that nobody really... It's all just very conjectural now, but maybe we'll come back in 20 years and we'll be like, figure that out.

• 43:28Chuck Nice?

  We'll have something for it.

• 43:29Neil deGrasse Tyson?

  We'll have the follow-up to this cosmic query, 20 years from now.

• 43:32Janna Levin?

  Yes, exactly.

• 43:33Neil deGrasse Tyson?

  We'll roll us in wheelchairs, not you, but me and Chuck.

• 43:36Janna Levin?

  Because I'll be doing my regenerative medicine.

• 43:40Neil deGrasse Tyson?

  So, we gotta go lightning round here. Chuck, let's do it.

• 43:43Chuck Nice?

  Here we go.

• 43:44Neil deGrasse Tyson?

  So, Janet, you're gonna answer in sound bites.

• 43:46Janna Levin?

  Okay, I'm amped.

• 43:47Chuck Nice?

  Uh, this is Bunders85 on Instagram and wants to know this. I know it's off-topic, but one of your last shows, uh, you were talking about the information on the surface of a black hole. What do you mean by information? Do you mean temperature or speed or what is information?

• 44:04Janna Levin?

  Uh, ultimately, we are completely definable in terms of our quantum numbers. It's just a list of facts about us, information about us, and relative locations and organizations.

• 44:15Neil deGrasse Tyson?

  My quantum number is 42.

• 44:17Janna Levin?

  So, of course Neil's his. So, it's something as simple as your mass, electric charge.

• 44:22Chuck Nice?

  The number of atoms in my body.

• 44:23Janna Levin?

  Well, let's take, let's take a single fundamental particle in your body. It has mass, charge, spin, and it's identical to every, let's call it an electron in this case, every other electron, identical. One's not a little bit heavier, one's a little bit lighter. And we're completely definable in terms of that information. And you cannot destroy that information.

• 44:38Chuck Nice?

  Interesting.

• 44:39Janna Levin?

  And so, so in quantum mechanics, you start, stop thinking in this...

• 44:43Neil deGrasse Tyson?

  Wait, wait, if I melt Chuck...

• 44:44Janna Levin?

  Yeah.

• 44:45Neil deGrasse Tyson?

  And he's a puddle.

• 44:45Janna Levin?

  Technically, all of that information is still in the universe.

• 44:48Neil deGrasse Tyson?

  Right.

• 44:49Janna Levin?

  Including in the heat that's lost. It's just arranged differently.

• 44:51Neil deGrasse Tyson?

  It's arranged, oh my god.

• 44:52Janna Levin?

  In principle.

• 44:53Neil deGrasse Tyson?

  Wait, wait, wait, no, no, how about the information?

• 44:55Chuck Nice?

  That's an awful thought, though. That's an awful thought!

• 44:56Neil deGrasse Tyson?

  If Chuck has a puddle on the ground,

• 44:58Janna Levin?

  Yeah.

• 44:58Neil deGrasse Tyson?

  that's a different Chuck from the Chuck I'm talking to right now. How's that information still there?

• 45:02Janna Levin?

  Yeah, so the inform-

• 45:03Chuck Nice?

  I will never change.

• 45:04Janna Levin?

  Well, techni- technically, changing- In for- having information preserved doesn't mean there can't be local change. Right? So I can definitely

• 45:13Neil deGrasse Tyson?

  Oh.

• 45:13Janna Levin?

  change things locally, but I still have to have the same information.

• 45:16Neil deGrasse Tyson?

  In the total system.

• 45:17Janna Levin?

  In the total system.

• 45:18Neil deGrasse Tyson?

  Oh, interesting.

• 45:18Janna Levin?

  So I have to be able to reconstruct something. It doesn't mean that there's no change.

• 45:22Neil deGrasse Tyson?

  With what's in the system.

• 45:22Janna Levin?

  With what's in the system.

• 45:23Neil deGrasse Tyson?

  Got it.

• 45:23Chuck Nice?

  But you don't have to necessarily be able to reconstruct the exact same thing. You just have to be able to utilize the same information.

• 45:30Janna Levin?

  Right. In principle, I should be able to, if I took a page of the encyclopedia and burnt it, I should be able to reconstruct it. In principle. Of course, nobody can ever really do that. It would take longer than the age of the universe, and we don't have that kind of computing power. So there's physical impossibilities, but-

• 45:44Neil deGrasse Tyson?

  Ignoring those complications.

• 45:45Janna Levin?

  Ignoring those complications. Um, but it's supposed to-

• 45:48Neil deGrasse Tyson?

  We've just solved teleportation.

• 45:49Janna Levin?

  Except for the black hole, the argument is that what's actually might be happening is that the information, as it's falling in, which is basically all, you know, everything.

• 45:58Neil deGrasse Tyson?

  Everything.

• 45:58Janna Levin?

  Everything.

• 45:58Neil deGrasse Tyson?

  Right.

• 45:59Janna Levin?

  Um, never actually makes it inside the black hole. It becomes encoded on the boundary, which is the event horizon, so it's actually a hologram.

• 46:07Neil deGrasse Tyson?

  Alright, so I got you.

• 46:08Chuck Nice?

  Lightning round here.

• 46:09Janna Levin?

  Alright, alright, that was not lightning enough. That wasn't lightning enough.

• 46:12Chuck Nice?

  Okay, okay, here we go. Um, this is Elias82 from Instagram says, NASA reported that Voyager 2 discovered two new details about interstellar space. How does that change our understanding of dark energy beyond our solar system? Or does it?

• 46:27Janna Levin?

  Um, it probably doesn't because it, it isn't a detector of dark energy or dark matter. We have no detectors of dark energy or dark matter yet. None successful. And so, what, but it is amazing that it's the first human-made object that's gone interstellar. And that really is quite spectacular. It's just broken out of basically the sun's magnetic influence, so it's able to get cosmic rays and things that, that are protected in the solar system by the sun's magnetic influence.

• 46:50Neil deGrasse Tyson?

  We used to think the solar system was how far out are the planets, and then you have like the Kuiper Belt of Comets, then you have the Oort Cloud. Then you say, well, really, at what distance does an object no longer know that the sun is in this direction?

• 47:01Chuck Nice?

  Right.

• 47:02Neil deGrasse Tyson?

  Because the sun has magnetic influences that go very far, and you reach the point where all the field measurements- Are sort of in this soup that permeates the entire galaxy. And so it's a transition from the sun is this way to I got stars in every direction.

• 47:19Janna Levin?

  Yeah.

• 47:20Neil deGrasse Tyson?

  And so.

• 47:20Janna Levin?

  It's still moving so slowly that it will take, what, 10,000 years to reach another.

• 47:24Neil deGrasse Tyson?

  Oh, you know, no, 70,000.

• 47:25Janna Levin?

  70,000 years.

• 47:26Chuck Nice?

  All right. This is from Robert Weaver, who says, thanks so much for educating and inspiring us. What news in science do you find most interesting and important right now with respect to your field?

• 47:40Janna Levin?

  Wow, that's a great question. Well, we do live.

• 47:43Neil deGrasse Tyson?

  In a soundbite.

• 47:44Janna Levin?

  Yeah. We are in a very lucky time because we have discovered bare black holes in this miraculous way. So I do think that the most exciting things have to do. One of them is, yeah, is eating Neil's Milky Way. So I do think it is where the small meets the large, and it will be that way for a long time. Meaning what the Big Bang tells us about dark matter and dark energy and the universe on the larger scale, and why those things are folded together, thinking about the universe on the bigger scale and on the small scale.

• 48:11Neil deGrasse Tyson?

  So where quantum physics meets general relativity.

• 48:13Janna Levin?

  For sure.

• 48:14Neil deGrasse Tyson?

  Is an unresolved territory.

• 48:17Janna Levin?

  That's right. And so that's why we use all these really extreme settings. Right. If you want to, if you want to understand where quantum mechanics meets gravity, you got to do it in the Big Bang or on black holes.

• 48:25Chuck Nice?

  All right. Next, Jeff. Here we go. This is Pablo Gristensco. I don't know, Pablo. I'm sorry. Uh, can you please help me put inside my head one more dimension? Three is fine, but how can I grasp more? That's a, what do you do with people? What do you do with people to let them understand?

• 48:49Janna Levin?

  I think it is absolutely imperative that everyone understands that nobody can just blanketly visualize higher dimensions. We're accustomed to looking at dimensions from the outside looking down. We can't do that. So what we can do with the kinds of things that Neil was describing earlier, which is imagine three dimensional cross sections of things. So visualizing a hypersphere, which is a higher dimensional sphere, as an intersection of it with our three dimensions, and it would be a series of, it would be a series of spheres.

• 49:16Chuck Nice?

  Evergreen, right.

• 49:17Janna Levin?

  That would max out, and then spheres would go back. But the one last thing is to do the, to do the difficult example of being a flatlander, and you will actually, just by going down a dimension, start to get it.

• 49:29Neil deGrasse Tyson?

  Yeah, yeah. And I can add that if, I've said this in a couple of Star Talks before, but here's another moment to do so. If a line is bounded by. Points.

• 49:39Chuck Nice?

  Mm-hmm.

• 49:41Neil deGrasse Tyson?

  And a square is bounded by lines. And a cube is bounded by squares. Then a hypercube is bounded by three-dimensional cubes. The sides of a hypercube are three-dimensional cubes. Right. And you just, and you mathematically, you just work your way up.

• 50:00Chuck Nice?

  Keep going up.

• 50:01Neil deGrasse Tyson?

  You just keep going up. The math will take you there.

• 50:02Chuck Nice?

  There, that's, there you go, math.

• 50:04Neil deGrasse Tyson?

  It'll set you free.

• 50:05Chuck Nice?

  There you go.

• 50:05Janna Levin?

  This is a real example where the math makes it a lot easier than trying to visualize it.

• 50:09Chuck Nice?

  Okay, there you go.

• 50:10Neil deGrasse Tyson?

  Said no one ever. The math, let's, let's convert this to math to make it easier.

• 50:15Chuck Nice?

  That's so great.

• 50:16Janna Levin?

  That's your higher-dimensional differential geometry.

• 50:18Chuck Nice?

  That's awesome. Okay, this is, uh, Eric Svenson, Mark Eric Svenson. Uh, he says this. Um, Neil, you have said before the dark matter should really be called dark gravity. And it really stuck with me and helped me understand it better. Do you have a similar and alternate name for dark energy? That better summarizes the phenomenon?

• 50:38Neil deGrasse Tyson?

  I'll give it a shock, but I want to hear.

• 50:40Chuck Nice?

  Let's see what Jana says.

• 50:42Neil deGrasse Tyson?

  What Jana says.

• 50:42Chuck Nice?

  Jana!

• 50:43Neil deGrasse Tyson?

  I, I would say, I would just call it, um, dark expansion stuff.

• 50:51Chuck Nice?

  We don't know what it is.

• 50:52Neil deGrasse Tyson?

  Dark stretching.

• 50:52Chuck Nice?

  Stretchy stuff.

• 50:53Neil deGrasse Tyson?

  Dark stretchy. But definitely dark gravity is what dark matter is. It is literally dark gravity. And I'm totally cool with that.

• 51:03Janna Levin?

  Are you totally cool with that?

• 51:04Neil deGrasse Tyson?

  Totally cool with that.

• 51:04Janna Levin?

  Well, is a neutrino dark gravity?

• 51:06Chuck Nice?

  Uh-oh.

• 51:06Janna Levin?

  Sure. That's a form of dark matter. Like, we have examples of forms of dark matter that we have detected. They're just not plentiful enough to explain so much of it.

• 51:14Neil deGrasse Tyson?

  Yeah.

• 51:14Janna Levin?

  But there are things called neutrinos which we do detect and they are dark, meaning they don't interact with light.

• 51:18Neil deGrasse Tyson?

  Right.

• 51:20Janna Levin?

  I wouldn't call neutrinos dark gravity. I'm pushing back a little on this.

• 51:24Neil deGrasse Tyson?

  Pushing back. They're messing with me.

• 51:26Chuck Nice?

  Let me tell you something, that was rough, man.

• 51:28Neil deGrasse Tyson?

  Oh, you, you got front row seat on that.

• 51:30Chuck Nice?

  Yeah, I'm nerd fighting. Right now I got my popcorn, I'm just like, nerd fighting.

• 51:34Neil deGrasse Tyson?

  Oh, this is good.

• 51:35Janna Levin?

  I will jump in with the dark energy, though. What if we thought of it as like an invisible? Ocean. Because that's sort of what, the dark energy is around us all the time. And it's, it's as though we're in a storm of dark particles and dark energy. It's just that it's, it's really that it's invisible. Is the thing. You can see right through it. It's not that if you had it in your hands, it would look dark. It's invisible.

• 52:02Chuck Nice?

  Right.

• 52:03Neil deGrasse Tyson?

  Right. So yeah, so both dark and energy really don't apply. We need a better name for it.

• 52:07Janna Levin?

  Yeah.

• 52:07Chuck Nice?

  Okay. There you go. So it's really in the name.

• 52:10Neil deGrasse Tyson?

  Vacuum, vacuum bath. Next one.

• 52:12Chuck Nice?

  All right.

• 52:12Neil deGrasse Tyson?

  Last one, last one, last one, real fast.

• 52:14Chuck Nice?

  Okay, okay, okay.

• 52:15Neil deGrasse Tyson?

  Jenna, half a sound bite.

• 52:16Chuck Nice?

  Here we go. Uh, this is Hector Salazar, who says this. Can other universes influence or overlap with our own? And is there any evidence that this might be happening?

• 52:30Neil deGrasse Tyson?

  This would be the parallel universe.

• 52:32Janna Levin?

  Yeah. Very speculative, but if you consider a universe, let's say we're floating on a three-dimensional membrane in a higher dimensional space, and there's another one of those floating also in the higher dimensional space, parallel, or in some sense.

• 52:46Chuck Nice?

  Now, do they both share this membrane you're talking about?

• 52:48Neil deGrasse Tyson?

  No, it's a different membrane.

• 52:49Janna Levin?

  Two separate membranes. So in that sense, we would call them universes. And yes, it is possible that they have interacted in the past, and that there would be some archaeological record of that, or in the future.

• 52:57Neil deGrasse Tyson?

  If they intersect, is there an intersection line? A three-dimensional line?

• 53:03Janna Levin?

  In which you live in both universes.

• 53:04Chuck Nice?

  Like a party, like a party wall.

• 53:06Neil deGrasse Tyson?

  Ooh.

• 53:08Janna Levin?

  So technically, if you mean by universe, the galaxies and everything you see, and not the whole spacetime, then technically, yes, two universes, two membranes can, can interact and can coexist.

• 53:20Neil deGrasse Tyson?

  I want, I want that.

• 53:21Janna Levin?

  Yeah. I like the idea of living on the boundary between two universes.

• 53:25Chuck Nice?

  Only if the people in the other universes aren't a-holes.

• 53:29Neil deGrasse Tyson?

  And as long as the laws of physics there are the same as yours. Because you don't want to decompose into a puddle of goo.

• 53:34Janna Levin?

  Yeah, that would be bad.

• 53:36Neil deGrasse Tyson?

  That would be bad. The charge of the electron is different.

• 53:38Janna Levin?

  Bad.

• 53:38Neil deGrasse Tyson?

  Bad. Very bad. Bad universe. Stay away. We gotta call it quits there.

• 53:44Janna Levin?

  Oh, man.

• 53:45Neil deGrasse Tyson?

  Always good to have you on, Janet.

• 53:46Janna Levin?

  Always fun to be here.

• 53:47Neil deGrasse Tyson?

  We don't have you enough.

• 53:48Janna Levin?

  Oh, I love it.

• 53:49Neil deGrasse Tyson?

  Thanks. So much fun. So much fun. Janet Levin, professor of physics up at Columbia and Barnard College. I'm Neil deGrasse Tyson, your personal astrophysicist, signing off for StarTalk, bidding you as always to keep looking up.