Cosmic Queries – Stoner Edition with Janna Levin

Summary

StarTalk Radio – Cosmic Queries: Stoner Edition with Janna Levin
Hosted by Neil deGrasse Tyson
Release Date: February 14, 2025

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Overview

In the "Cosmic Queries – Stoner Edition" episode of StarTalk Radio, astrophysicist Neil deGrasse Tyson teams up with co-host Matt Kirschen and renowned physicist Janna Levin to delve into some of the most intriguing questions about black holes, the fabric of space-time, and the very nature of the universe. This episode combines deep scientific insights with a relaxed, conversational tone, making complex topics accessible and engaging for listeners.

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1. Gravitational Waves and the Concept of Repulsive Gravity

Timestamp: [04:18]

The episode kicks off with a fascinating question from Matthew Power in New Jersey: “If there were two black holes orbiting one another and generating powerful gravitational waves, is there a possibility that a small object, perhaps a ping pong ball, could actually be carried away by the waves, thus making gravity a repulsive force in this particular case?”

Neil deGrasse Tyson responded enthusiastically, saying, “Wow. This is like a surfing ping pong ball. I love it.” This metaphor sparked a detailed discussion about the nature of gravitational waves and their effects on objects.

Janna Levin elaborated, explaining that while gravitational waves do indeed cause stretching and squeezing in space-time, their effect on small objects like a ping pong ball would be negligible. She clarified, “I don't think it would have enough power to actually carry you along.” However, she also introduced the concept of dark energy, which acts as a repulsive force on cosmic scales, causing the accelerated expansion of the universe.

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2. The Universe's Expansion: Into What Are We Expanding?

Timestamp: [09:32]

Matt Kirschen presented another thought-provoking question: “What is the universe expanding into?” This age-old query challenges our understanding of the universe's boundaries and the very concept of "outside" the universe.

Neil deGrasse Tyson humorously remarked, “Everybody wants to know that,” setting the stage for a deeper exploration.

Janna Levin provided clarity by stating, “The universe is the whole space. There’s really no logic to thinking of it expanding into something else.” She emphasized that the universe's expansion doesn't require an external space; instead, space itself is stretching.

Levin further explained, “We are moving with the expansion of the space. We are not moving with respect to our local area.” This analogy likens the universe's expansion to "a surfer riding the wave," helping listeners visualize this abstract concept.

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3. Time: A Human Invention or a Fundamental Aspect of the Universe?

Timestamp: [15:17]

One of the more philosophical questions posed by listener Scott Allen was: “Is time just a human invention?” Combining ideas about energy and the perception of time leads to profound discussions about existence and reality.

Janna Levin addressed this by differentiating between time as a dimension and time as a perception. She noted, “If we want to meet, we don’t just specify a point in space. We have to say a moment in time.” This underscores that while our perception of time is influenced by human cognition, time itself operates as a fundamental dimension within the fabric of the universe.

Conversely, Neil deGrasse Tyson referenced a quote by John Archibald Wheeler: “Time is what keeps everything from happening at once.” This highlights the necessity of time in organizing events and processes in the universe.

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4. Time Dilation and Its Practical Implications

Timestamp: [23:50]

The discussion shifted to the practical applications of Einstein's theory of relativity, specifically time dilation. Matt Kirschen relayed a question from Jeff Johnson: “Why does gravity or high speed cause an entity to move faster through time?”

Janna Levin clarified that it's actually gravity and high speeds that cause time to slow down relative to an observer in a different frame of reference. She illustrated this with the example of astronauts on the International Space Station (ISS) compared to those on Earth, explaining how both gravitational potential and velocity affect their experience of time.

Neil deGrasse Tyson added, “If we didn’t correct for the time dilation, we would never be able to catch our Uber because it wouldn’t be in the right location.” This underscores the real-world necessity of accounting for time dilation in technologies like GPS, which rely on precise time measurements to function accurately.

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5. Black Holes: Temperature, Composition, and Hawking Radiation

Timestamp: [36:01]

A listener from the Czech Republic, Jindric Procupek, asked: “I read that black holes are almost zero Kelvin inside. Why are they so cold and not very hot? Is there a temperature gradient between a black hole center and its event horizon?”

Janna Levin responded by explaining that black holes are cold because they are essentially empty; the dense matter that once formed them has collapsed beyond the event horizon. She emphasized, “Black holes are cold because they're empty.”

She further discussed Hawking radiation, detailing that smaller black holes emit more radiation and are thus hotter, while larger ones emit less and are colder. This emission leads to the eventual evaporation of black holes over incredibly long timescales.

Neil deGrasse Tyson connected this to popular culture, mentioning how the final stages of black hole evaporation would result in explosive bursts of gamma rays, akin to high-energy fireworks in the cosmos.

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6. Dark Matter and Black Holes

Timestamp: [43:55]

Gonzalo Castilla from Mexico posed an intriguing question about dark matter: “If dark matter can interact gravitationally with normal matter, it is attracted and eaten by a black hole just like normal matter. What happens with the dark matter as the black hole evaporates? Could there be a dark matter version of Hawking radiation?”

Janna Levin affirmed that Hawking radiation doesn't discriminate between types of matter. She stated, “The black hole will figure out how to radiate all of the information that went into it. That includes dark matter information.” This implies that dark matter would also be emitted through Hawking radiation if it interacts gravitationally.

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7. Wormholes and the Possibility of Time Travel

Timestamp: [44:56]

Dylan raised a speculative question about wormholes: “How would we open up a wormhole? Hypothetically speaking, what steps are taken? How much energy would it take?”

Janna Levin addressed the theoretical challenges, explaining that while wormholes can be described mathematically, they require negative energy to remain open—something not observed in nature. She mentioned, “People at KipThorn were writing down wormhole solutions decades ago, and they just looked around and said, well, we don't see any matter like that in the universe.”

Neil deGrasse Tyson humorously referenced the famous "1.21 gigawatts" from Back to the Future, highlighting the immense energy requirements and the current impracticality of creating or sustaining wormholes.

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8. Concluding Thoughts and The Stoner Edition Naming

Timestamp: [49:14]

As the episode wrapped up, the hosts playfully debated the appropriateness of labeling this episode the "Stoner Edition." Janna Levin humorously noted, “Anybody who knows me knows if I'm stoned, I'm asleep.” Ultimately, the playful spirit prevailed, acknowledging the relaxed and whimsical nature of the discussions.

Neil deGrasse Tyson concluded with, “This has been StarTalk. Cosmic Queries, black holes, space-time continuum, which we dubbed the Stoner Edition. I'm Neil deGrasse Tyson, your personal astrophysicist. Keep looking up.”

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Notable Quotes:

• Matt Kirschen [04:18]: “If there were two black holes orbiting one another and generating powerful gravitational waves, is there a possibility that a small object, perhaps a ping pong ball, could actually be carried away by the waves, thus making gravity a repulsive force in this particular case?”

• Neil deGrasse Tyson [15:17]: “Time is what keeps everything from happening at once.”

• Janna Levin [36:01]: “Black holes are cold because they're empty. There's no dense object left once matter has collapsed beyond the event horizon.”

• Neil deGrasse Tyson [30:57]: “If we didn’t correct for the time dilation, we would never be able to catch our Uber because it wouldn’t be in the right location.”

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Final Thoughts

This episode of StarTalk Radio masterfully blends complex astrophysical concepts with relatable analogies and humor. Neil deGrasse Tyson, along with Matt Kirschen and Janna Levin, navigate through listeners' cosmic queries, providing clarity on topics ranging from the enigmatic nature of black holes to the fundamental aspects of time and space. Whether you're a seasoned science enthusiast or a curious newcomer, this "Stoner Edition" offers a captivating journey through the wonders of the universe.

Stay Connected:

• Matt Kirschen on Twitter: @Makirshan
• Janna Levin on Twitter: @JanaLevin
• StarTalk Radio: Subscribe on SiriusXM Podcasts+, Apple Podcasts, and other major platforms for more enlightening discussions.

Keep Looking Up!

Transcript

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[Neil DeGrasse Tyson]

CT mobile.com welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil DeGrasse Tyson here, your personal astrophysicist. We're gonna do cosmic queries today. Everything, black holes and spacetime, everything. I got with me, my co host, Matt Kirschen. Matt, welcome back, dude.

[Matt Kirschen]

Thank you, thank you. I'm joining you from my family's spare bedroom in London right now.

[Neil DeGrasse Tyson]

Oh, you mean your parents basement where you live?

[Matt Kirschen]

That's exactly it. Yeah, I commute to LA every day from. From the basement where all my toys and games are.

[Neil DeGrasse Tyson]

I knew you were full geek, but the full the whole story. You're still in your parents basement.

[Matt Kirschen]

That's it.

[Neil DeGrasse Tyson]

You can confess that you're in safe grounds here to admit that to us.

[Matt Kirschen]

This is no judgment podcast.

[Neil DeGrasse Tyson]

No judgments at all. Good to have you back. And you're the host of Sometimes Science.

[Matt Kirschen]

Probably Science. Neil.

[Neil DeGrasse Tyson]

Probably Science. Neil, Probably Science, on which I have been a guest.

[Matt Kirschen]

You have indeed I have and I.

[Neil DeGrasse Tyson]

Enjoyed my time there. So Matt, while I know a little bit about black holes and a little more about space time, I don't count myself a among the world's experts. But we have a friend of StarTalk who is of course, that's Jana Levin. Jana, welcome back to StarTalk.

[Jana Levin]

Thanks, I'm glad to be here.

[Neil DeGrasse Tyson]

Yeah. Yeah. Jana, you're like a neighbor up the street from the American Museum of Natural History. You're a professor of physics and astronomy at Barnard College of Columbia. And it's just great to have you. Just a friend of what we do and a supporter of all of this. Yeah, I love camping and to lend your expertise. You're not lending it cause we're not giving it back. You're giving us your expertise on. On black holes, cosmology, the space time continuum and all that goes with it. So just before we start off, I just want to alert people that in your spare time, you actually are one of the founders of a marvelously conceived project, Pioneer Works over in Brooklyn, across the river. You merge art and science in highly creative and imaginative ways. I just want to congratulate you.

[Jana Levin]

Thanks, Neil.

[Neil DeGrasse Tyson]

On even going there and you've been. And you've been at it for, like, years now.

[Jana Levin]

Yeah, I really appreciate that. Yeah, we. We have a live programming where we feature scientists in conversation. You've been over. We've had parties with you, Neil, and.

[Neil DeGrasse Tyson]

Yeah, but. But you haven't put me on the stage. I was there to thank you.

[Jana Levin]

I'm waiting for the right time.

[Neil DeGrasse Tyson]

Oh, okay.

[Matt Kirschen]

I have also been there and not on the stage. They didn't want my expertise, but I went to Matt.

[Neil DeGrasse Tyson]

You and I don't cut it. Yeah, Good enough for the audience, but not to actually do it.

[Matt Kirschen]

I mean, I think I'll get there eventually, but I'm not so sure about you, Neil. I've got some deep expertise to share.

[Jana Levin]

I'm happy to put you both to work. Be careful what you wish for. So the big project there has been lately broadcast. Pioneer Works broadcast since the pandemic, which is our virtual manifestation. It's Pioneer Works beyond the Walls, where we cover art, science, music, tech, kind of multimedia extravaganza.

[Neil DeGrasse Tyson]

Excellent. So now you can reach a far greater audience than who shows up in Brooklyn. All right, so, Matt, you collected questions from our Patreon members. They have exclusive access to our Cosmic Queries format, and everyone else gets to hear their questions. And so what do you have lined up for us?

[Matt Kirschen]

I did. Well, I've got.

[Neil DeGrasse Tyson]

This is like a grab bag. It's a grab bag of black holes and stuff.

[Matt Kirschen]

Yeah, there's a really nice assortment of questions. I'm going to start off with this one from Matthew Power, my kind of superhero namesake. That's.

[Neil DeGrasse Tyson]

But you're Matt Kirschen, and this is Matthew.

[Matt Kirschen]

It's Matt Power. This is Matt from New Jersey, who is also currently reading Black Hole Blues, which is one of Janna's books. I've read that. It's an excellent book. And Matt is also enjoying it. And Matt says, my question is, if there were two black holes orbiting one another and generating powerful gravitational waves, is there a possibility that a small object, he says perhaps a ping pong ball, could actually be carried away by the waves, thus making gravity A repulsive force in this particular case.

[Neil DeGrasse Tyson]

Wow. This is like a surfing ping pong ball. I love it.

[Jana Levin]

That's. What do you think?

[Neil DeGrasse Tyson]

Oh, I love the idea. So. Because probably he's thinking deeply. Because if you're surfing on a wave in the ocean, the water isn't actually moving, it's just going up and down. And you're somehow exploiting this fact, moving with it.

[Jana Levin]

Yeah, I think it's a subtle question. I wondered about this, but I haven't ever really worked it out. I'm sure somebody might off the cub know the answer. But definitely what you're doing in space time if you're near those two black holes is you're falling freely. We literally call it free fall. So you're falling freely on the natural curves in the space. So if those curves are changing, that's certainly going to change your fall. For instance, the Earth is falling around the sun on a curve, on a circle. And if the sun were to disappear tomorrow, the gravitational waves would radiate out, taking the time it takes until it reaches us. And then we'd go in a straight line as though the sun was gone. In some sense we are definitely moving with those waves. But thinking of it as like surfing, it's cool. I don't know.

[Neil DeGrasse Tyson]

Right. If we're not so heavy as the Earth, let's say, or something as responsive as a ping pong ball. Wouldn't the waves. Wouldn't the expanding gravitational wave from the disappeared sun or from the collapsed black hole, will that have any effect on us at all to push us? How can a wave move out but we can't now move with it?

[Jana Levin]

Yeah, I mean, the gravitational energy in the wave can be quite powerful. Right. The collision of the two black holes was the most most powerful event human beings have detected since the detection of the Big Bang. Right. And all of it came out in the gravitational waves. But actually I think their effect is really quite weak in the sense you would feel the squeezing and the stretching as you kind of bobbed around on the wave. But I don't think it would have enough power to actually carry you along. But we also do know, I think the question was also about repulsive gravitational forces. And actually we do know that gravity can be repulsive. So for instance, the dark energy in the universe creates a repulsive effect on the expansion. So the universe is expanding, things are getting farther apart because of the dark energy. And that's happening at an accelerated rate.

[Neil DeGrasse Tyson]

Yeah, but you're calling that gravity. And are we allowed to do that yet?

[Jana Levin]

What do you mean in what sense.

[Neil DeGrasse Tyson]

You say, well, there's this dark energy, and it's actually the opposite of gravity. So are you legitimately calling it negative gravity?

[Jana Levin]

No, I'm not calling it negative gravity. I'm saying that when we think about curved space time, that coming together is not the only possibility. Although that is with Newton's laws in general relativity. When I think of dark energy as a particular source for the way it deforms spacetime, we see a very clear example where its effect on spacetime is expansive and.

[Neil DeGrasse Tyson]

Oh, wait, wait. I got a good answer. I got another good answer. Can I raise my hand? Jana, I'm raising my hand in the front row.

[Jana Levin]

You're the boss. You're the boss.

[Neil DeGrasse Tyson]

Okay, Neil. Neil, thank you. Thank you, Janet. So just thinking about this more holistically. The very expansion of the universe is carrying galaxies in the fabric of the expanding spacetime. So in a way, we are moving, in a sense, not through space, but with space. And space is carrying us. Oh, yeah, we know it's not a gravitational wave, but it's. I'll take it as something it's sort of surfing, even if it's not.

[Jana Levin]

Yeah, that's excellent. The dark energy is just a particular example of that causing the expansion in an accelerated way. But lots of things cause the universe to expand, like the fact that it's full of light and energy in all directions causes the universe to expand. And I think you really hit it on the head, Neil. We are moving with the expansion of the space. We are not moving with respect to our local area. Right. So that is like the surfer riding the wave.

[Neil DeGrasse Tyson]

Yeah. Yeah. Cool. All right, Matt.

[Matt Kirschen]

Well. Well, I'm going to jump from a question that is very theoretical to one that I know you have a good answer to, because I know this is something you've both been asked before. Alexander Newhouse wants to know, what is the universe expanding into?

[Neil DeGrasse Tyson]

Yeah, Janna.

[Jana Levin]

Yeah.

[Neil DeGrasse Tyson]

Everybody wants to know that.

[Jana Levin]

I know you've done this a bunch of times.

[Neil DeGrasse Tyson]

No, no, I just make stuff up. What I think, what I've read. But you actually work on these problems, so let's hear it out of the horse's mouth.

[Jana Levin]

Well, if. Let's take it as though the universe was expanding into something, just pretend, then we would be saying, oh, there's some distance. The universe has traveled into this other space. But what we mean by the universe is the space. So there's really no logic to thinking of it expanding into something else. The universe is the whole space. There are some relational possibilities that you can think of where the expansion of the universe is like a map of the universe where we're only reading the legend between things as changing over time, but the map itself doesn't move into anything else. That's one kind of very strange relational way of thinking about it. But, no, we do not need to nest the universe into another universe to have it expand.

[Neil DeGrasse Tyson]

Okay, I get that, but. But who? What. Okay, so let's up this game a notch. What conditions would. What dimensionality, what location, what state of existence must one have to observe the entire expansion of our universe?

[Jana Levin]

Well, you.

[Neil DeGrasse Tyson]

Okay, that's from the outside.

[Jana Levin]

So there is no way to stand outside the universe?

[Neil DeGrasse Tyson]

No, not really. But so. But so what?

[Jana Levin]

I think you're trying to disprove the existence of God with me right now. What kind of trouble are you getting into?

[Neil DeGrasse Tyson]

I don't think I really mentioned God in that.

[Jana Levin]

And know the entire universe at one time. There's no way of.

[Neil DeGrasse Tyson]

Yeah, who are you to say that you can't. There is not some platform, some vista outside of everything we know and see that can just simply observe what's going on.

[Jana Levin]

Well, by observe, we mean collect particles and interact, and we do that through paths in space time. So if you want to literally be in a position where you're gathering light so that you can see the universe and deduce what's happening to it, you're really talking about interacting with something, and that requires that we be in the same universe. Now, I mean, you could fundamentally say, you're no fun.

[Neil DeGrasse Tyson]

You're no fun.

[Jana Levin]

We could say things that I think are actually quite.

[Neil DeGrasse Tyson]

Matt, she could have said, God is out there and he's watching us. All right? Or Santa Claus, he knows when you are bad at him.

[Matt Kirschen]

And then roll credits.

[Jana Levin]

So it is interesting to push this idea and to say, look, these ideas about space being infinite or being finite or expanding, these are just ways of talking. We could also talk differently about the entire universe. Only as relations, only as interactions. And that' only thing we understand, that interactions happen over a certain span of space and time. And there's no need to even think about geometry at all or to think about the universe as a space at all. It just appeals to our intuition.

[Neil DeGrasse Tyson]

Wow. Okay.

[Jana Levin]

You're looking at me like I've had this woman on the show many times.

[Neil DeGrasse Tyson]

Okay, Matt, she's crossed over, and I don't know that they're bringing her back at this point. Okay. I mean.

[Jana Levin]

And we know that we're often fooled by these interactions. So right now I have the illusion that you're a solid person, that Matt's a solid person, but really, you're mostly empty space. These are illusions that we cling onto to more easily comprehend the world, but we know that they're not true.

[Neil DeGrasse Tyson]

Matt is.

[Matt Kirschen]

A lot of people say that about me. Neil is solid. Neil is solid. There's nothing going on in here.

[Neil DeGrasse Tyson]

So, Janet, you're referring to the fact that atoms are mostly completely empty.

[Jana Levin]

Right. And then even if you look at fundamental. What the fundamental particles are with atoms, we only understand them in terms of the way in which they interact with things. That's the meaning of an electron, is the way it interacts with things. So in some sense, we're just these sort of lists of interactions.

[Neil DeGrasse Tyson]

Yeah, she got all philosophical.

[Matt Kirschen]

That's making me very much quickly go.

[Neil DeGrasse Tyson]

To the next question before it gets.

[Matt Kirschen]

Worse, because you got so philosophical. I'm going to jump onto Scott Allen's question because Scott from Arlington, who, by the way, gives the caveat that Scott is stoned right now. Like, putting that right in there. And if Scott is still stone trying to listen to these answers, I think we're gonna put him in some real trouble.

[Jana Levin]

We should do a stoner version of this show.

[Matt Kirschen]

I'll host it and just get my mate. I mean, that's basically. Is my podcast. That is probably side. We're just winging it.

[Neil DeGrasse Tyson]

Startalk for stoners. Oh, my gosh. We get all the topics best suited for when you're high. Oh, my gosh. You know, Janet, we'll bring you back. That's gonna be a show. I promise our audience. That's gonna be a show.

[Jana Levin]

I just fall asleep. It'll be a very boring show.

[Neil DeGrasse Tyson]

Yeah, while you're eating potato chips. Yeah. Okay.

[Matt Kirschen]

So Scott says, is everything just a form of energy? Is time just a human invention? Combining the two ideas is what we call life. And everything we can observe and understand with our limited senses and minds simply a flow energy constantly changing form. There is no beginning, there is no end. There is no past. There is no future. There is just the present in whatever form of energy we can sense and understand with our mind. That is Scott's question. Make of that what you will. Professional scientists.

[Neil DeGrasse Tyson]

Yeah. Okay. Wait. Did you just give the answer? And you said definitely? And now to the next question.

[Matt Kirschen]

I think the answer is yes, and everything's fine right now.

[Jana Levin]

And I just think he's definitely stoned. That is such a stoner.

[Neil DeGrasse Tyson]

But let's think about this. What confidences do I want to restate the question, what confidences do we have? Janet, can you and I offer as scientists that there is a physical reality and we're not all just perceiving ourselves in the moment?

[Jana Levin]

And.

[Neil DeGrasse Tyson]

I mean, what evidence do we have?

[Jana Levin]

Yeah, you made it worse for me, man.

[Neil DeGrasse Tyson]

Universe has meaning and existence outside of our perceptions.

[Jana Levin]

Yeah. I mean, we're all. I mean, which one of us is the one perceiving? Am I in your mind or solely? Or are you solely in my mind.

[Neil DeGrasse Tyson]

Or are we both in Matt's mind?

[Matt Kirschen]

Before Scott started combining his ideas, there are two questions at the beginning that I don't. That are more grounded in, I think, physical of theory, that is everything just a form of energy? And also, is time just a human invention? And I think. I think those two are questions that are potentially.

[Jana Levin]

Yeah.

[Matt Kirschen]

More answerable.

[Jana Levin]

Well, to deal with the first one, yes, I think matter and everything is a form of energy that interacts in described ways.

[Neil DeGrasse Tyson]

Don't think that you know that. Janet, be careful how you use the word think, okay? Like you think it might rain tomorrow. But, you know, matter is energy.

[Jana Levin]

Okay, Right. It's true. We know that matter is definable.

[Neil DeGrasse Tyson]

Thank you.

[Jana Levin]

Essentially, yeah. And. And that is interesting. I mean, I think that's also related to this kind of tangent we went on, which is that what does it mean to have atoms in your body? What does it mean to be made up of atoms as it means that you have a certain amount of energy and that those particles interact in very prescribed ways. That's what makes an electron different from the positron is just the prescribed interactions, if not their energies. So, yeah, that's really all we are. It's beyond that. To say what's real is again, part of this illusion. We have to cope with our perceptions of the world.

[Neil DeGrasse Tyson]

We'll take a quick break and when we come back, we'll pick up the second part of that question. Whether time is just some kind of a human construct. With the help of Jan11 giving us her insights into the universe, on Start Cosmic Queries.

[T-Mobile Representative]

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Minimum of 4 lines for 25 per line per month with autopay discount using debit or bank account. $5 more per line without autopay. Up to $830 off each phone via 24 monthly bill credits plus taxes, fees and $10 device connection charge for well qualified customers. Contact us before canceling entire account to continue build credits or credit stop and balance on required finance agreement to bill credits and if you pay UP devices early ct mobile.com.

[Neil DeGrasse Tyson]

Hi, I'm Ernie Carducci from Columbus, Ohio. I'm here with my son Ernie because we listen to StarTalk every night and support StarTalk on Patreon.

[Jana Levin]

This is StarTalk with Neil DeGrasse Tyson.

[Neil DeGrasse Tyson]

We're back. Star Talk Cosmic queries. I got Matt Kirschen as my co host. Matt, how do we find you on social media?

[Matt Kirschen]

I'm Matt Kirschen. On Twitter, I think Makirshan on the Instagram I very rarely use. Twist is the main place I am.

[Neil DeGrasse Tyson]

Okay.

[Matt Kirschen]

And if you don't know the spelling, just kind of get vaguely close and Google will find me.

[Neil DeGrasse Tyson]

Yeah. Okay. And we'll find you on Twitter then. Without the underscore. Cause that's where you mostly that is. That's me and Jana. Tell me about your social media footprint.

[Jana Levin]

Yeah, I'm more on Twitter. An 11, 2 N's like Anna and I'm on the Insta. Same handle. Okay. I sort of treat them a little differently on Instagram, I kind of post my personal stuff. So my personal business and on Twitter.

[Neil DeGrasse Tyson]

Okay. We want to get all up in your situation. We go there. Okay.

[Jana Levin]

You know. Yeah, exactly. You know, not exactly what I had for lunch, but yeah, so. But Twitter, I have pretty serious conversations with people. If they want to ask questions, I'm there. I love answering questions when I'm in the mood. At least, you know.

[Neil DeGrasse Tyson]

Okay, Very good. Very good. All right, so we left off. What's the name of that last questioner?

[Matt Kirschen]

So, Scott, we left off. His part of the question was, is time just a human invention?

[Neil DeGrasse Tyson]

Yeah. So, Janet, the only thing I can say about time is a quote I remember from Einstein or from his student, John Archibald Wheeler was that time is invented to make motion look simple. Have you heard that?

[Jana Levin]

I have heard it. I feel like it was Wheeler because he said lots of witty things. I also think it was Wheeler who said, time is what keeps everything from happening at once. Which is a good one.

[Neil DeGrasse Tyson]

All at once. Yeah.

[Jana Levin]

Okay, so.

[Neil DeGrasse Tyson]

And just, just. I got to throw it in here. I first noticed the woman who would become my wife in a class taught by John Archibald.

[Jana Levin]

Oh, wow. No way. I didn't know that.

[Neil DeGrasse Tyson]

Yeah, we took the class together. Yeah. I was sitting in the back row. She was in the front row. So I don't. She probably didn't notice me, but I noticed her. Yeah, I can say I notice her in the space time continuum on the chalkboard. Right, okay, so what do you have to say about his construction?

[Jana Levin]

Well, I think. I definitely don't think it's a human construct whether time exists in this kind of block time model of the universe where the past exists, the future exists, every bit as much as left and right exist. But we're confined on a particular path through this four dimensional space where time is the fourth dimension. That wouldn't be just human beings though, that would be. Everything would be confined to that space. I presume my cat's death comes before it's, you know, after its birth, rather. And, you know, I just presume flowers die after they bloom and that those are things that are happening to everything in the universe. There are other models that time is sort of not an invention of the mind, but it's like it emerges from very subtle processes and that in some sense it's not fundamental. But I think that again, it's a very good thing to talk about. So if we want to meet, we don't just specify a point in space. We have to say a moment in time. And it's very convenient that we all are able to find that moment in time and collect and get together at that moment in time. So that suggests it's not just a figment of our imagination or a human construct.

[Neil DeGrasse Tyson]

So maybe I should save this for the Stoner edition. But if you could find a region of the universe where nothing changes, then time cannot possibly have meaning.

[Jana Levin]

Absolutely. And in fact, that's kind of a death of the universe model that the universe will. Everything that can fall into black holes will possibly, if the expansion doesn't dominate and those black holes will evaporate into random particles, and then the expansion will just make it so that there's only one particle in the entire observable horizon and that's disconnected from all the other particles. And so there will be no meaning to time passing. I mean, even for me to experience time passing, there has to be change, which is my thoughts changed, my breath accumulated. There's actual measurable change that I experience as the passage of time. So that is true that we do have internal clocks, but they are very well aligned with our external clocks, making it seem as though there is something external and universal.

[Matt Kirschen]

Well, while we're talking about external and internal clocks, Jeff Johnson wants to know, why does gravity or high speed cause an entity to move faster through time?

[Jana Levin]

Oh, I See, the question. Time dilation is the question. Yeah. Why does time.

[Neil DeGrasse Tyson]

But first he got it backwards. So gravity slows down time, not speeds it up.

[Jana Levin]

Yeah. So it doesn't actually slow. My experience of time. So my experience of time if I'm standing near a black hole is exactly like, very ordinary. My nicely made watch that I had once synced with my friend back at a safe space station is. Is working perfectly well. It's still matching the number of breaths I take. Time seems to be passing completely normally.

[Neil DeGrasse Tyson]

Your heart rate, everything.

[Jana Levin]

My heart rate, everything, is absolutely normal. I don't get any benefit out of this dilation. The dilation is only relative to somebody far away. And to somebody far away. I look like I'm moving slowly, like I'm breathing slowly, like I'm aging slowly, like my watch is ticking slowly. So it's only relative to them that it looks odd. But in my experience, it's quite normal. I think the deeper question is, why does this happen? We can think of both gravity and moving quickly as creating rotations between the space times of two observers. If one observer thinks that this is left and another observer is facing them, they understand that they're going to disagree about which way is left. They're not surprised, but they know they can just rotate their systems and then they'll agree in some sense. As you go closer and closer to the black hole, it's as though you're rotating in space time. Some of what you were calling space is folding into some of what your friend was calling time. That leads to time almost as though you're rotating left and to right, almost as though you've rotated time away entirely relative to your other observer.

[Neil DeGrasse Tyson]

And so, Matt, we should just rename this show Star Talk with Stoners.

[Jana Levin]

I don't think it's fair to cut stones.

[Neil DeGrasse Tyson]

It is hidden. It is happening in front of our eyes.

[Matt Kirschen]

There is a beautifully related question as well on this note from.

[Neil DeGrasse Tyson]

Wait, wait, wait, wait, wait, wait. Matt, I just gotta, like. I just gotta wrap my head around what Jana just said. So, Jana, So what you're saying is you use left, right, as an interesting analog to this. What you're saying is when you are moving faster in the vicinity of a black hole, your time coordinate is, let's use the term, rotates in such a way that it's giving of itself to a space coordinate.

[Jana Levin]

That's right.

[Neil DeGrasse Tyson]

So one is losing time relative to the other.

[Jana Levin]

Exactly. And just like you can rotate left all the way into right at the edge of a black hole, in particular, you've basically rotated your time away entirely. And in fact, when you cross the event horizon, what your friend far away thought was a region in space, a center of the black hole, is for you, a direction in time. So you've rotated it completely by the time you cross the event horizon to the point where you think that the dire singularity at the center isn't a point in space at all. It's in your future. And it is as inevitable that you will crush into that singularity as the passage of time is inevitable. So you can see.

[Neil DeGrasse Tyson]

And that was Roger Penrose Result. That was Roger Penrose, wasn't it?

[Jana Levin]

Yeah, yeah, yeah. Actually, I wrote this little article after he won the Nobel Prize for that Beautiful Work in 1965 for Pioneer Works Broadcast, actually, because we do this series called Picture this, where you draw. Scientists write about technical articles like technical drawings. And Roger Penrose has the most wonderful drawing that he drew in this 1965 paper where he shows basically time starting to move in a spatial direction. He shows that rotation, and he proves that at the event horizon, what's happened is basically time is starting to point inward towards the black hole.

[Neil DeGrasse Tyson]

It's crazy. And I love the left right starter analogy there. You know what? That reminds me. So, Matt, you ever hear this joke? It's funny. So someone says, well, two wrongs don't make a right. But then you can say, but three rights make a left. You ever try that? Just try. Make three left turns. You just turn right. If you do the geometry on that, it works out. All right, cool. Janet, thanks for that answer. I think we should rebrand this for Stoners, AKA for Stoners, the Stoner edition of Cosmic Queries. Matt, keep them coming.

[Matt Kirschen]

Well, so Frederic Johansson asks, and this is related, because you just talked about the difference of effects of both speed and gravity. Frederick wants to know, if I stand on the equator, my head would age less compared to my feet due to the speed difference. But wouldn't we have the opposite effect due to gravity? Would my feet or head age more in the end? So I believe he's asking that if he's standing on the globe, his head is moving faster than his feet because it's further out, but also his head is further away from the gravitational center of the Earth than his feet. So do these two things both have an effect on the time perception of your head and your feet? And if so, do they cancel each other?

[Jana Levin]

I would have to. I would have to actually do the calculation because both are pretty tiny. Right. But I can tell you that with like the GPS units, we see the effect of the time dilation when we send signals to satellites and back again. And they have two effects. One is you're deeper in the gravitational potential. So let's say we take the twins like one astronaut that was in the ISS and the other twin astronaut who stayed on Earth, the Kelly twins, which one actually was younger, the one who stayed on Earth deeper in the gravitational potential. Well. Or the one who was traveling very quickly in the iss and it's actually a known answer and I forget which one it was. I think the speed of the ISS out dominates over being on the Earth. In that case, I'm pretty sure.

[Neil DeGrasse Tyson]

Okay. However, with GPS satellites, the fact that they are much farther away from Earth than the International Space Station, that they experience much, much less strength of gravity, which speeds up their time relative to us. And so their time that they send us is pre corrected to accommodate the fact that their clocks tick faster.

[Jana Levin]

So.

[Neil DeGrasse Tyson]

Right, Janet, you have to do the math. Right, because there are two competing effects and to know for sure. But I agree with you everything I know about the orbiting astronauts which are in low Earth orbit rather than Middle Earth orbit. Matt, it's not Middle Earth like you know. Okay, just to be clear, orbit, keyword.

[Matt Kirschen]

There, not a basement.

[Neil DeGrasse Tyson]

It's Leo, Mio and Geo. Right, Low Earth orbit, Middle Earth orbit and geosynchronous orbit. So when you do the math there, the lower gravitational field wins out over what effect their speed has on their timekeeping.

[Jana Levin]

Oh, interesting. Yeah, interesting. So thinking about the gps, we could also think about how if we didn't correct for the time dilation, we would never be able to catch our Uber because it wouldn't, it wouldn't be in the right location. And I learned this from Neil recently, that it's actually the rotation of the Earth. That's the issue that if the satellite in a. Let's suppose we lost a second. If the correction was never made and the error accumulated up to, let's say a second, then if you consider how quickly the Earth is rotating and that the grid would be changing, you would find that we could be off by several blocks. So you'd be trying to catch your Uber in Chinatown and it would be in Little Italy.

[Neil DeGrasse Tyson]

Which is story of five, six blocks away. Uber's never adjacent. These are adjacent communities in lower Manhattan. Little Italy.

[Jana Levin]

Yes, they're adjacent neighborhoods in China.

[Neil DeGrasse Tyson]

Yes, yes they are. For those who are not native to the city. Let's take a quick break and when we come back, more cosmic queries. Stoner Edition with Gen 11. We're talking about black holes cosmology in the space time continuum. And I got Matt Christian to help me. We'll be right back.

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[Neil DeGrasse Tyson]

We'Re back. Third and final segment of Cosmic Queries and Space Time Continuum Edition, which we are dubbing Cosmic Queries Stoner Edition, based on the answers we've been getting and what kind of state of mind we have to be in to even follow them, much less understand them. So, Janna, again, it's always good to have you here. Your last two books. So one of them was the Black Hole Blues published by. Was that Knopf?

[Jana Levin]

Yeah, by Knopf.

[Neil DeGrasse Tyson]

Is that right? Yeah, yeah, yeah. Black Hole Blues. I didn't know black holes had emotional states.

[Jana Levin]

Well, the people who were searching for black holes had emotional states.

[Neil DeGrasse Tyson]

Oh, God.

[Jana Levin]

They had the black hole blues. They had the black hole.

[Neil DeGrasse Tyson]

Oh, I got you. So this is a story of black holes in our field of astrophysics and the relationship we have to them. Got it, got it. And more recently you have a book called the Black Hole Survival Guide, which is like a pocketbook. Fits right in your coat pocket.

[Jana Levin]

Yeah.

[Neil DeGrasse Tyson]

How useful did you. How soon do you think such a book will be useful? Where everyone has to have one?

[Jana Levin]

Yeah, they have to have a survival guide. Well, I hope not very soon at all. But we are in ordinary.

[Neil DeGrasse Tyson]

But for the sake of the sales of your book.

[Matt Kirschen]

Well, the sales of your book. Let's stoke some worry in the public.

[Jana Levin]

I have a spoiler alert. It doesn't end well.

[Neil DeGrasse Tyson]

Oh, yeah, yeah, yeah.

[Jana Levin]

There you go. The survival guide doesn't go well.

[Neil DeGrasse Tyson]

All right.

[Jana Levin]

It's pretty much many ways to die.

[Neil DeGrasse Tyson]

We'll keep a copy of this in our go bag. Right when you disaster strikes.

[Jana Levin]

So don't you have a Book titled Death by Black Hole. I've always wanted to steal that title from you.

[Neil DeGrasse Tyson]

Oh, Death by Black Hole. Yeah, yeah I do. It's one. So that title is the title of one chapter in a book that goes a lot in different ways.

[Jana Levin]

Right. It was this collection of essays as I remember.

[Neil DeGrasse Tyson]

Yeah, that's right, that's right. On all manner of things in the universe.

[Jana Levin]

Yes, the survival guide should also be called like Death by Black Hole.

[Neil DeGrasse Tyson]

Okay, all right, so it's the non survival guide if it's Death by Black Hole. All right, Matt, what more do you have for us?

[Matt Kirschen]

Well, I'm gonna turn this to some black hole survival questions because we've got a few and they' so from the Czech Republic, Patreon patron Jindric Procupek. I hope I've got that close to correct. Asks you. I read that black holes are almost zero Kelvin inside. Why are they so cold and not very hot? Due to a high pressure caused by enormous gravity forces and lack of heat escape. And is there a temperature gradient between a black hole center and its event Horizon?

[Neil DeGrasse Tyson]

And what's 0k anyway? Janna?

[Jana Levin]

Literally it just means particles are so cold, they have so little energy that they're just not moving. It's as though we experience temperature. What we're really experiencing is the collection of atoms moving at a certain rate and a certain speed on average. And that creates the temperature. The faster that they're moving, the hotter it feels. And the slower they're moving, the colder they are. It is true. There's an expression PV equals NKT that you know, in highly pressured situations the temperature can go up and.

[Matt Kirschen]

Right. That's the thing I, the, the level of physics that I understand. Like a bicycle pump gets hotter if you, and if you, if you spray one of those compressed air canisters, they get cold because you're.

[Jana Levin]

Yeah, exactly.

[Neil DeGrasse Tyson]

Janna, I can't believe you wrote it on the chalkboard.

[Matt Kirschen]

I love that Janna's in front of a. The people who are audio only are not aware that Janna is in. You look like you're posing for a professor photograph right now.

[Jana Levin]

What were we talking about?

[Matt Kirschen]

Oh, we were talking about the compressor.

[Neil DeGrasse Tyson]

Matt was sharing his life experience that in a bicycle pump you. Because he's living in his parents basement, he doesn't own a car, he just has a bicycle. So in his bicycle pump the valve gets hot.

[Matt Kirschen]

All I've got is compressed air to keep me happy.

[Neil DeGrasse Tyson]

Right. And a spray can. As the air releases, the nozzle feels cold. So the pressure can Heat up or cool it, depending on which way it's going. So what's happening inside a black hole? Is the person right about it being zero?

[Jana Levin]

No, but they're not right for a very interesting reason. So we know that as the core of a remnant star, what's left after it goes through some very violent throes at the end of its life, continues to collapse and is in fact extremely dense and probably absolutely an unusual, extraordinary, exceptional state of matter. We know that because we see neutron stars, which aren't even black holes. They're a step on the way to black holes. They don't quite make it there. And we know that they're incredibly unusual in terms of their composition. But once it makes it to be the black hole, it has created a curve in space time that is so sharp that we know not even light can escape. That's what we mean by the event horizon. And you might think, therefore the event horizon of black hole is full of dense stuff, but it's not actually, because the star can no more sit there than it can expand outward at the speed of light. You can almost think of spacetime as like a waterfall raining into the black hole. And it would have to swim against the waterfall just to stay at the event horizon. And it can't do this. So it just continues to get dragged in with the waterfall of space time. And, you know, this is the great mystery. What happens to the star? We don't know. But it's gone. The star is gone. So black holes are cold because they're empty. So if I go up to the event horizon of a black hole, nothing's there. There's no dense object. There's nothing solid. It's empty space. So I like to say, you know, and I've said this I'm sure on your show before, black holes are more like a place than they are a thing. They're like a place in the universe, but there's really no matter left.

[Neil DeGrasse Tyson]

But you can measure the gravity that it has, right? So something's got to be there.

[Jana Levin]

Yeah, that's right. It has gravitational energy in the curvature of the space time. There is energy in the curvature of the space time. That is a gravitational energy. So, you know, it's often really hard to define gravitational energies. But in the case of a black hole, I can actually have a well defined mathematical prescription for measuring its gravitational gravitational energy. And it happens to equal, not surprisingly, the mass of whatever fell into it. So it's as though the matter, like throws its heft into the gravitational imprint. But you don't, but the stuff is gone now. There's another question you could ask about temperature, which is about the Hawking radiation. So at the event horizon, we do think that through this very subtle quantum process, black holes do have a temperature actually, and they are radiating actually. But the bigger the black hole, the colder they are and the smaller they are, the hotter they are. So they have, they're very cold. They live their lives absorbing things, not emitting. But at the end, you know, very, very far, far, far future of the universe, those black holes will eventually evaporate away and the final stages will be explosive.

[Neil DeGrasse Tyson]

Yeah. In fact, if I remember correctly, the original paper that described this phenomenon by Hawking explained these as. That they would be bursts of high energy gamma radiation because they, right at that last moment would be at its hottest and very hot things emit gamma rays.

[Jana Levin]

Exactly.

[Neil DeGrasse Tyson]

And so it's interesting.

[Jana Levin]

Yeah. So if you are foolish enough to try to make a black hole in the laboratory, it will explode on you because the smaller they are, the more unstable they are. And you can kind of figure out like how big would it be if it was like kind of a stick of dynamite versus what you're describing, gamma rays or nuclear weapon grade. And so you're kind of ill advised to make a small black hole.

[Matt Kirschen]

But if you do, you should start with a bigger one just for sake of it.

[Jana Levin]

Well, then you're gonna fall in. So you gotta, you know, it's a real. So I tried to.

[Neil DeGrasse Tyson]

Wow, what a trade off that is. And urban. It could suck in the earth.

[Jana Levin]

So.

[Neil DeGrasse Tyson]

Yeah, that would ruin your day.

[Jana Levin]

That would ruin a lot of days, people's days.

[Neil DeGrasse Tyson]

So, Janet, we can't call a black hole an area of nothing if it contains the severe curvature of the space time continuum. Because that is something.

[Jana Levin]

Yeah, I guess. Right. That's fair. We can say. What do we really mean by nothing?

[Neil DeGrasse Tyson]

Matt, Notice how she didn't say it was right? You said it was fair.

[Jana Levin]

You're absolutely right. Space time is something. And space time has energy.

[Neil DeGrasse Tyson]

It's a thing.

[Jana Levin]

Space time moves and it's a thing. And in that sense it's a thing. But it's also by definition space, which is a place. I'll take that. They very much act like things. Black holes move around, they orbit, they can fall together, they can collide. But when we talk about the size of a black hole, we're talking about a shadow. That's all we're talking about. We're talking about a shadow like the shadow of a tree. And there's nothing there. No matter.

[Matt Kirschen]

While we're talking about matter, so listen to Gonzalo Castilla from Mexico asks, and Gonzalos mentions black matter. I'd imagine this is what we would also call dark matter. Unless there are two different things. I think it's probably dark matter, so I'll say dark matter for this. I imagine that's a language thing. But if dark matter can interact gravitationally with normal matter, it is attracted and eaten by a black hole just like normal matter. Right. What happens with the dark matter as the black hole evaporates? Could there be a dark matter version of Hawking radiation? Or it only radiates normal matter, and a black hole has some sort of mechanism that transforms this dark matter into normal matter.

[Neil DeGrasse Tyson]

So, Jana, that's a really interesting question. Oh, my gosh. But as we're running short on time, can you, like, sound bite that answer? Is that possible?

[Jana Levin]

Yeah, absolutely. The black hole will figure out how to radiate all of the information that went into it. If this works. So that includes dark matter information so that the fact that it was dark would come out. In principle, everything comes out.

[Neil DeGrasse Tyson]

Okay, so Hawking radiation. That calculation does not discriminate between ordinary matter or dark matter or any other kind of matter.

[Jana Levin]

Nope. It can be electrons and positrons. It can be light coming out in the Hawking radiation. It can be dark matter. Pairs. Pairs of dark matter.

[Neil DeGrasse Tyson]

And that assumes. So everything you said assumes that dark matter is actually comprised of matter and not some other mystical substance. Right. Okay.

[Jana Levin]

Right. And there are people who think that black holes themselves might be enough to explain the missing mass and the dark matter.

[Neil DeGrasse Tyson]

Yeah, I'm not a monk, so that's.

[Jana Levin]

Not a particle answer at all. Yeah.

[Neil DeGrasse Tyson]

Okay, Matt, keep them coming.

[Matt Kirschen]

All right, so Dylan, there's a couple of faster than light questions. So Dylan asks. I've heard a lot about wormholes on this show and have a question. How would we open up a wormhole? I know as of right now, they're impossible. But hypothetically speaking, what steps are taken? How much energy would it take? And could we just use a black hole? How do we cut space time?

[Neil DeGrasse Tyson]

Janet, we're waiting for this. And why aren't you giving us the wormhole? We're so disappointed.

[Jana Levin]

I know, I'm busy. I'm gonna do it in the future and then come back.

[Neil DeGrasse Tyson]

Oh, that's.

[Jana Levin]

I'm gonna do it later.

[Neil DeGrasse Tyson]

Good answer. Good answer, Matt. That reminds me. During the science march, which is sad that in the United States, we needed a march to defend science Back several years ago, one of the placards said, what do we want? Time machine. When do we want it? It doesn't matter.

[Jana Levin]

That's perfect. I think at MIT once scheduled a time traveler conference for the previous year. They were like, let's meet in 2019 and have a time traveler conference. Nobody showed up.

[Neil DeGrasse Tyson]

Nope. Yeah, time travelers didn't show up.

[Jana Levin]

Yes, I can tell you this about the wormhole. We absolutely, on paper, know how to make a wormhole. So basically what you do is you write down the shape of the space time you want, namely a wormhole shape, and then you force matter and energy to create it. You ask then, well, what does the distribution of matter and energy have to be to create this shape? So you can go backwards and deduce what kind of matter and energy would be required. The problem is it requires negative energies, and that's not something we see in our ordinary experience. Everything has positive energies. Negative energies are super weird. Some people think that they're forbidden in nature. The one circumstance in which you can get negative energies is in some strange quantum situations. I've actually wondered about this. Could we create where you have, like, finite spaces made out of metals, and the quantum oscillations or the quantum vibrations create a certain negative energy between, like, these strange geometric configurations.

[Neil DeGrasse Tyson]

So you need the energy, the negative energy, to. To pry open a hole that would otherwise, on its own, want to collapse and just make a black hole, I guess.

[Jana Levin]

Yeah, it just wants to keep pinching closed.

[Neil DeGrasse Tyson]

So that sounds really dangerous to enter one of these, because suppose you're in one, and then it collapses on you. That's a bad day.

[Jana Levin]

That would be right there. I was just saying.

[Neil DeGrasse Tyson]

Okay, so we're nowhere near this now, even though you can make it happen on paper.

[Jana Levin]

Yeah, I mean, you know, people at kipthorm, they were writing down wormhole solutions decades ago, and they just looked around and said, well, we don't see any matter like that in the universe. So we got to go back to the drawing board and think of a new way.

[Neil DeGrasse Tyson]

Okay, so just because something is mathematically possible doesn't mean the universe is going to cooperate. That's really what it comes down to.

[Jana Levin]

There's other time machines that we know we can make. We can take two cosmic strings, which are literally strings of energy tension and energy density, and cross them in a very funny way. That creates a kind of cut in space time that allows you to do a little time travel jig. But the problem is they have to be infinitely long. An infinite amount of energy so there's never anything that seems compatible with the universe that we live in. And even Kurt Godel first, who was friends with Einstein, used to walk to the Institute for Advanced Study with him in the mornings to talk. And he was inspired by Einstein's work. And he wrote down a description of a hypothetical universe that was rotating, not our universe. And he showed that you could travel in time in these. This peculiar space he invented. And Einstein didn't dispute it. It was correct mathematically. But we just don't live in those kinds of.

[Neil DeGrasse Tyson]

Okay, just admit it, Janet. All we really need is 1.21 gigawatts. Okay, that's really all we need. Just admit it.

[Matt Kirschen]

I believe it's pronounced gigawatts.

[Neil DeGrasse Tyson]

Oh, excuse me. So, Jen, I think we gotta call it quits there. We ran out of time.

[Jana Levin]

Ah, shame. It's always so fun.

[Neil DeGrasse Tyson]

Okay, so Matt, with your permission, I don't want to call it the stoner edition unless we have total buy in from the three of us. Can we call it that?

[Jana Levin]

I'm fine calling it the Stoner edition, but anybody who knows me knows if I'm stoned, I'm asleep. Synonymous stonings equals sleeping.

[Matt Kirschen]

And anyone who knows me knows I have a green card. And.

[Neil DeGrasse Tyson]

That'S right, Northern Europeans have green cards too.

[Matt Kirschen]

I have a green card, which means I can't get the other kind of green card.

[Neil DeGrasse Tyson]

So we're good here. So, Janet, thanks for coming back to StarTalk. It's always good to have you. And continued. Good luck with. It's not luck. It's your talent that helps make pioneer works. What it and what it will continue to grow, to become. So keep that going there.

[Jana Levin]

Thank you so much.

[Neil DeGrasse Tyson]

And Matt and I are still waiting for our invitation to be something other than in your audience.

[Jana Levin]

Now. I can't wait. Oh, are you gonna get an invitation?

[Neil DeGrasse Tyson]

You got it, Matt. Always good to have you, dude.

[Matt Kirschen]

Lovely to be here. Thank you for having me.

[Neil DeGrasse Tyson]

This has been startalk. Cosmic queries, black holes, space time, continuum, which we dubbed the stoner edition. I'm Neil Degrasse Tyson, your personal astrophysicist. Keep looking up.