Exploring Hidden Dimensions with Brian Greene

Summary

StarTalk Radio – Exploring Hidden Dimensions with Brian Greene

Host: Neil deGrasse Tyson
Co-host: Chuck Nice
Guest: Brian Greene (Theoretical Physicist, Columbia University)
Date: March 31, 2026

---

Episode Overview

This extended episode of StarTalk Radio features acclaimed theoretical physicist Brian Greene, exploring the mind-bending frontiers of the universe: the multiverse, quantum mechanics, string theory, hidden dimensions, infinity, and more. In a format blending scientific rigor and wry humor, Neil deGrasse Tyson, Chuck Nice, and Brian Greene dig into the latest insights, the state of “theory” versus “hypothesis,” the limits of knowledge, and the nature of existence itself, wrapping with a lively Cosmic Queries session. This summary captures the episode’s core discussions, notable quotations, and the natural, engaging dynamic of the StarTalk crew as they make the cosmos accessible and astonishing.

---

Key Discussion Sections and Insights

1. Brian Greene’s Background and Science Communication

• Intro to Brian: Dual professor of mathematics and physics, bestselling author ("The Elegant Universe," "Until the End of Time"), World Science Festival co-founder.
• Blending Science and Culture:
  • “People need to see science as part of the fabric of culture, as opposed to something off there on the side that you are forced to take in school. And then you leave it.” (Brian Greene, [05:47])

---

2. Defining the Multiverse and Many-Worlds

• What is the Multiverse?
  • “The idea of a multiverse is the umbrella concept for any variation on the theme where our world is not the entirety of reality.” (Brian Greene, [07:11])
  • Many-Worlds is one kind of multiverse, specifically from quantum mechanics.
• Many-Worlds Interpretation of Quantum Mechanics:
  • Electrons exist in multiple places at once until measured. When observed, every outcome happens, each in a separate universe.
  • “If you look at the mathematics, which comes from Erwin Schrödinger, you can't transition from many possibilities to the single definite outcome of experience.” (Brian Greene, [10:08])
  • Hugh Everett’s view: There’s no real ‘splitting’—all possibilities coexist in a “giant uber realm.” ([12:00])
  • “When you look at the math, if you just take it at face value, this is what it seems to say.” (Brian Greene, [13:16])
• Conundrum of Reality:
  • Each observer sees only a single outcome, but from a “God’s eye view” all results/existence are equally real.
  • Chuck: “That is so freaky, man.” ([13:04])

---

3. Math, Reality, and the Limits of Theories

• Is Math the Ultimate Reality?
  • Brian’s past view: “Defending mathematics as like, the deep truth of the world.”
  • Present view: Math is a tool, not necessarily ‘the truth’ of reality ([17:15])
  • “I do not say [many worlds] is true because it comes out of the equations.” (Brian Greene, [17:53])
• Math’s Triumphs and Cautions:
  • Example: Kepler’s faith in platonic solids to describe the cosmos (ultimately incorrect) versus Lemaitre’s work on big bang expansion (math revealed physical truth Einstein had missed) ([20:11])
  • “The math discovered that.” – Chuck, on Lemaitre ([21:09])

---

4. Infinity and the Quantum Multiverse

• Infinite Worlds and Hilbert Space:
  • There are seemingly uncountable universes, structured mathematically in “Hilbert space.”
  • “This space that Hilbert introduced has just the right mathematical properties to be the space in which all these worlds live.” (Brian Greene, [22:43])
• Gödel's Incompleteness and Decidability:
  • Are there facts about the physical universe fundamentally unprovable, even in math (“undecidable”)? Unclear if translated into physical science. ([23:09])
• Statistically Unlikely Events:
  • Even the most improbable events will happen in infinite universes:
    • “No matter how unlikely it is to happen, it will be realized in some world. So what does it mean to say something is unlikely if you're sure it's going to happen in some world?” (Brian Greene, [34:18])
• Infinite Levels:
  • Set theory: There are “levels of infinity” (Aleph numbers), with some infinities larger than others.
  • “There are more than an infinity of numbers between 0 and 1.” (Brian Greene, [39:55])

---

5. String Theory, Extra Dimensions, and The Quest for Unification

• State of String Theory:
  • Vibrating strings as fundamental, not point particles. The math naturally predicts hidden extra dimensions.
  • “The basic ingredient is a filament that looks like a tiny piece of string…it can vibrate in different patterns and the different particles…correspond to different vibration patterns.” (Brian Greene, [57:31])
  • Unifies all forces, including gravity, but “the pathway from the fundamental equations to physics we can see in the laboratory is fraught.” ([58:49])
• Extra Dimensions:
  • Forced by the equations. “There’s an equation in string theory…for this theory to be self consistent… D must equal 10. That is where the extra dimensions are forced upon you by the equations.” (Brian Greene, [62:37])
  • We don’t see them—“probably too small for us to see with the naked eye.” ([62:45])
• What’s Missing?
  • No experimental predictions yet verified. Some suggest ‘string hypothesis’ may be the more accurate term than ‘string theory’. ([66:01])
  • “We’re using the word wrong, and I agree with people who are sticklers on that.” (Brian Greene, [66:36])
• Role of AI:
  • Greene describes giving a breakthrough problem to ChatGPT-like models; “within a half hour, it was able to reproduce the results that took us months to get.” (Brian Greene, [56:48])

---

6. Multiverse Flavors and Their Testability

• Inflationary/Bubble Multiverse:
  • Bubbles within a larger space—potentially detectable in principle ([47:03])
• Brane Worlds (String Theory’s Multiverse):
  • “Our universe is sort of like one piece of bread in a big cosmic loaf.” Extra slices represent other universes; gravity might “leak” between them ([49:06])
  • Gravity can escape from our brane because the graviton (as a closed string) isn’t anchored. Electromagnetic force (open strings) is brane-bound. ([52:10])
• Testing Multiverse Theory:
  • No current experiment can demonstrate the quantum many-worlds multiverse directly. For brane worlds, possible indirect effects (e.g., “gravity leakage”) have been theorized but not observed. ([48:58])

---

7. Life, Probability, and Existence

• The Improbability of Existence:
  • The sequence of events from Big Bang to modern life is incredibly improbable, yet “here each of us are.” (Brian Greene, [43:46])
  • Tyson references Dawkins: “Most people who could ever exist will never even be born. So we should cherish life.” ([45:44])
• Does Multiverse Guarantee Life Everywhere?
  • Within the quantum multiverse, “all things compatible with the laws of physics are real.” Unlikely events are inevitable somewhere. ([28:08])
• Life’s Universality and “Cheapness”:
  • Life emerged quickly on Earth once conditions stabilized; could be common wherever conditions permit.
  • “How cheap is life?” (Chuck Nice, [88:07])
  • Brian: “It formed relatively quickly.” (Brian Greene, [88:16])

---

Notable Quotes & Memorable Moments

• On Many Worlds:
  • “If you look at the math, if you just take it at face value, this is what it seems to say.” (Brian Greene, [13:16])
  • “Our experience shows one reality. Quantum mechanics speaks of many possibilities.” (Brian Greene, [09:52])
• Infinity Revealed:
  • “There are more than an infinity of numbers between 0 and 1.” (Brian Greene, [39:55])
  • “I’ll never get to one. I’ll never get to one.” (Chuck Nice, joking about the continuum, [41:35])
• Math’s Power and Danger:
  • “That was my lesson that, you know, I ain't going there.” (Neil deGrasse Tyson, on beauty of math leading astray, [20:11])
• The Wonder of String Theory:
  • “You stare at the equations, and out pops Einstein’s equations from general relativity.” (Brian Greene, [58:21])
  • “The major obstacle is...the pathway from the fundamental equations to physics we can see in the laboratory is fraught.” (Brian Greene, [58:49])
• Cosmic Queries - Mindblowing/Comic Points:
  • “Could the reason we cannot see dark matter also account for the expansion of the universe due to dark matter moving faster than light?” (Listener Patrick Dees; Brian: “For a particle to be a particle of dark matter, it has to have mass. Once it has mass, it can't travel faster than speed of light. So the ideas don't meld together in a consistent way.” [109:50])
  • “Is time a dimension or a field?” (Listener Michael De La Morena, [84:27])
    • Brian: “The deep lesson of Einstein was that space and time can be affected by their environment, and they in turn create the very environment…elevated them to be dynamical qualities of the world.”
• Black Hole Paradox:
  • “He [Hawking] gave him an encyclopedia of baseball. A lot of information.” (Brian Greene, on Hawking losing a bet about black hole information, [79:10])
• On Consciousness in the Multiverse:
  • “That means we are living forever. Their reincarnation are all over this.” (Neil deGrasse Tyson, [106:37])
• On String Theory as a Field:
  • “Maybe you shouldn't call it string theory...maybe call it the string hypothesis.” (Brian Greene, [66:05])

---

Highlighted Timestamps for Key Segments

• Definition of Multiverse/Many Worlds: [06:59]-[13:16]
• Math vs. Physical Reality, Kepler/Lemaitre anecdotes: [17:15]-[21:11]
• Infinity, Hilbert Space, Gödel: [22:43]-[24:38]
• String Theory, Extra Dimensions, AI in Research: [53:10]-[58:49]
• Cosmic Queries Segment Begins: [73:00]
• Information Paradox and Black Holes: [75:37]-[79:19]
• Time as a Field or Dimension: [84:39]-[85:49]
• Quantum Immortality and Many Worlds/Identity: [105:09]-[106:37]

---

Tone, Style & Dynamic

• The conversation is intellectually ambitious yet accessible, blending deep dives into math, physics, and cosmology with playful banter, cultural references (Star Trek, Rick and Morty, The Planet of the Apes), and plenty of comic relief (provided by Chuck Nice).
• Tyson keeps the discussion grounded by connecting abstract ideas to historical context, thought experiments, and everyday analogies.
• Greene offers clear, thoughtful explanations, showing openness about the limits of current science and the need for humility in the face of cosmic mysteries.

---

Final Takeaways

• Many of the world's deepest mysteries—about existence, consciousness, the fate of information, the structure of reality—remain unsolved, with mathematics both illuminating and confounding.
• Multiverse theories exist in many versions (inflationary, quantum, brane-world) but remain difficult to test directly; string theory continues to be a fertile theory (or “hypothesis”) with elegance but lacking empirical proof.
• Mathematics is a powerful interpretative tool, but its relationship to physical reality is nuanced, sometimes leading, sometimes misleading.
• Probability, infinity, and the sheer scope of quantum mechanics urge humility and awe, and the very fact of existence—of each individual—is profoundly unlikely.
• As Greene and Tyson note, scientific understanding sometimes comes quickly, sometimes takes centuries; the journey is as important as the destination.

---

For more: Listen to StarTalk Radio and Brian Greene’s upcoming book in 2027, celebrating the centennial of quantum physics. And, as always, keep looking up!

---

This summary has highlighted and organized the essential elements of this episode, omitting ads and non-content segments (except a quick reference to sponsor jokes for continuity). For those who haven’t heard the episode, it provides a thorough, authentic guide to the questions, spirit, and scientific richness of “Exploring Hidden Dimensions.”

Transcript

[Sponsor/Announcer]

Startalk radio is supported by Claude from Anthropic. Science isn't about rushing to conclusions. It's about sitting with the uncertainty until it starts to make sense. Claude is the AI built for that kind of thinking and anthropic committed to not running ads in Claude. So when you're chasing down an idea, there's nothing pulling you towards someone else's agenda. Try Claude for free at Claude AistaTalk and see why problem solvers choose Claude as their thinking partner.

[Chuck Nice]

Hey, are you traveling soon? Imagine arriving and actually understanding the language. Imagine being able to communicate with the people that are there waiting for you to arrive. Rosetta Stone's immersive, intuitive method helps you naturally absorb your new language. The lessons are simple. They fit into your day wherever you want them to. You learn at your own pace. And you can access the lessons on your laptop or your phone or your tablet. It's super eas, very convenient and important because of course, everybody loves it when you're able to communicate with them in their own language. Are you ready to start learning a new language this spring? Visit rosettastone.com startalktoday to explore Rosetta Stone and choose the language that's right for you. Now, for me, that language was Spanish. One, because you know, I live in this hemisphere and there's a lot of Spanish speaking people. But two, because I secretly am listening to my mother in law talk about me behind my back and she doesn't even know that I understand what she's saying. All right, I've shared too much. How about you? Go to Rosetta Stone.com startalk today to explore Rosetta Stone and choose your language. Go to Rosetta Stone.com startalk right now and begin your language learning journey today

[Neil deGrasse Tyson]

in an extended version of StarTalk.

[Chuck Nice]

That's right.

[Neil deGrasse Tyson]

I'm loving it. All things you never knew, you didn't know about what's going on in the Universe. Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil DeGrasse Tyson, your personal astrophysicist, got with me. Chuck Knight, baby.

[Chuck Nice]

What's up, Neil?

[Neil deGrasse Tyson]

All right, this is a special cosmic queries edition, okay. Because half of it is not going to be cosmic queries.

[Chuck Nice]

Oh, okay.

[Neil deGrasse Tyson]

Half of it. I'm just gonna be talking to my man.

[Chuck Nice]

Okay, For a moment, I. I thought you meant you were just gonna talk up the street. Yes.

[Neil deGrasse Tyson]

Professor of mathematics and physics and physics at Columbia University.

[Chuck Nice]

That's right. Let it go for Brian Green. Returning champion, Brian Green.

[Brian Greene]

Thank you. Thank you.

[Chuck Nice]

Fan favorite, by the way.

[Neil deGrasse Tyson]

You know that, right?

[Brian Greene]

Appreciate it.

[Chuck Nice]

Our fans love you.

[Brian Greene]

That's great to hear.

[Neil deGrasse Tyson]

We love you because you're a theoretical physicist.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

And while of course, data matter, people like just thinking in an unfettered way about what could be true or not true about the universe. And there's so many things being bandied about lately, especially in the quantum realm, that we thought we'd bring you in for a special recording where there are no time limits on this. We're just gonna talk universe. Everything cool, weird, and wacky about the universe.

[Brian Greene]

Let's do it.

[Neil deGrasse Tyson]

And you're the man for it, by the way. When you're not here, I just sort of fumble over how I. What? I know. But when you're here, we got them.

[Chuck Nice]

Yep, exactly.

[Neil deGrasse Tyson]

Okay, so let's remind people you your specialty, I mean, historically is. Is particle physics, specifically.

[Brian Greene]

Yeah. I certainly came from the particle physics side. Quantum mechanics and then moving toward gravity, which of course, is the other end of the spectrum. And that's what took me to string theory, which is this attempt to put them both together.

[Neil deGrasse Tyson]

We'll get there. We're totally gonna get there. All right, so that means there's no scale of physics that's out of your reach.

[Brian Greene]

Well, I wouldn't quite go that far.

[Chuck Nice]

But you are kind of covering it all.

[Neil deGrasse Tyson]

Particles in the universe.

[Chuck Nice]

What else is left?

[Brian Greene]

Well, what's left are the complicated things like the brain, like the mind, like consciousness, like biology, you know, so we stay simple.

[Neil deGrasse Tyson]

You do the easy stuff. The physics is the easy stuff. You've written multiple bestselling books.

[Chuck Nice]

Yeah, a lot.

[Neil deGrasse Tyson]

And the one people remember most, perhaps, was the Elegant Universe.

[Chuck Nice]

Was that your first?

[Brian Greene]

That was my first.

[Chuck Nice]

That was your first book.

[Neil deGrasse Tyson]

And it was a runaway bestseller.

[Chuck Nice]

Yeah, yeah.

[Neil deGrasse Tyson]

For W.W. norton. And your most recent book in 2020, came out just in time for Covid until the end of time.

[Chuck Nice]

Nice. Wow.

[Brian Greene]

Sitting right.

[Chuck Nice]

Very person of you religious would be

[Neil deGrasse Tyson]

the end of days.

[Chuck Nice]

Right, the end of days.

[Neil deGrasse Tyson]

So what I like about you is you have a breezy way with communicating your complex physics thoughts. And in no small measure is that honed in books that are written for the public A. B, your co founder, I think, with your wife. Tracy Day, former news correspondent.

[Brian Greene]

Yes.

[Neil deGrasse Tyson]

Interviewed me many years ago, I think for NBC, Goodwill, abc.

[Chuck Nice]

Abc.

[Neil deGrasse Tyson]

Yeah, yeah, yeah. And Tracy Day co founded the World Science Festival.

[Chuck Nice]

Oh, wow.

[Brian Greene]

We did.

[Neil deGrasse Tyson]

Yeah. Now that's just. Initially, it's just being badass because it was New York, which is the world,

[Chuck Nice]

though I'm not sure if you realize this.

[Neil deGrasse Tyson]

So I haven't attended as many of these as I have always wanted. But those that I attended, I thoroughly enjoyed the juxtaposition of the science and the art and the music and just science as culture.

[Brian Greene]

Yeah, I mean, that's the point. I mean, much of what your work is about the same thing. People need to see science as part of the fabric of. Of culture as opposed to something off there on the side that you are forced to take in school. And then you leave it.

[Neil deGrasse Tyson]

Right. You leave it behind. And so I think World Science Festival does that brilliantly congratulate you. Appreciate that year in and year out, it's still going strong.

[Brian Greene]

Yep.

[Neil deGrasse Tyson]

Yep. So before we get to cosmic queries, because we. We poll our. Our fan base, our donors, really the Patreon members, and they all know you. So they're coming in with questions hot and heavy, straight in. And I worry that I might be asking some questions that they'd be asking. Well, is that allowed?

[Chuck Nice]

Yeah. So what? Okay. And for everyone that we come across that you have asked, that they will ask because they've already submitted. You will just give us $5

[Neil deGrasse Tyson]

because

[Chuck Nice]

that's how much it costs to be

[Neil deGrasse Tyson]

a Patreon member at the entry level.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

Okay. So, Brian, let's. Let's just right off the bat, we hear about the multiverse, okay. On one side of a fence, and then you cross the other side of the fence, and then we hear about the many worlds hypothesis in quantum physics. Do these have anything to do with each other?

[Brian Greene]

Yeah, they do. The idea of a multiverse is the umbrella concept for any variation on the theme where our world is not the entirety of reality.

[Neil deGrasse Tyson]

Oh, so that would cover all cases.

[Brian Greene]

All cases.

[Chuck Nice]

Oh, it's a multiverse or not.

[Brian Greene]

Yeah.

[Chuck Nice]

So the multiverse is under the many worlds.

[Brian Greene]

Well, I say many worlds is under.

[Chuck Nice]

Under the multiverse.

[Brian Greene]

The multiverse, the umbrella idea.

[Chuck Nice]

Okay. So the multiverse encompasses every single.

[Brian Greene]

And there are. There's something like 10 versions of many worlds that have emerged from radically different ideas. And quantum mechanics is simply one of those.

[Neil deGrasse Tyson]

Okay, So I was mistaken to think that the more, dare I say, traditional multiverse descriptions, there's one where there's multiple bubbles within our space time.

[Brian Greene]

Sure. That's the inflationary multiverse.

[Neil deGrasse Tyson]

You know, I'm thinking that's the multiverse.

[Chuck Nice]

I'm bringing it down, by the way. Inflation, affordability, it's a hoax.

[Neil deGrasse Tyson]

Universe is not really inflated.

[Chuck Nice]

It's not really Inflated. It's the best price it's ever built. There's never been a better price for the universe.

[Brian Greene]

Oh.

[Neil deGrasse Tyson]

Anyway, and I'd learned many worlds when I first learned quantum physics, where you needed some way to get out of the conundrum that you're observing statistical phenomena.

[Brian Greene]

Yes, exactly.

[Neil deGrasse Tyson]

So catch us up on the many worlds specifically, and then tell us how that plugs into the multiverse.

[Brian Greene]

Yeah. So when people develop quantum mechanics, this is now going back to the 1920s and 1930s.

[Neil deGrasse Tyson]

The Centennial Decade of quantum mechanics.

[Brian Greene]

Precisely. Which is why I'm writing a book on it that will be published in this decade.

[Neil deGrasse Tyson]

But to catch people up on that.

[Brian Greene]

Yeah, yeah, exactly.

[Neil deGrasse Tyson]

Yeah. Very good.

[Brian Greene]

And the progression of the ideas, beginning in the 1920s, was to note that a particle. Let me be specific, like an electron, it could be partly here and partly there, 50% here and 50% there. And the question was. But when you look and you measure, you always find the electron here or there. You never find it in a blended mixture, being at two locations.

[Neil deGrasse Tyson]

Okay.

[Brian Greene]

And people scratch their head for a long time trying to figure out what. How do we transition from a theory that describes a fuzzy haze of possibilities to the single definite reality when we make an observation or an experiment?

[Neil deGrasse Tyson]

How much of that definite reality was a bias coming out of classical physics?

[Brian Greene]

Well, you could say all of it. Because our brains are big, and we think they probably operate according to laws that are biased toward the classical. The big stuff.

[Neil deGrasse Tyson]

Yeah.

[Brian Greene]

And our experience.

[Neil deGrasse Tyson]

There's an object, it drops. There's a thing, you move it.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

There's just stuff that kind of makes sense.

[Brian Greene]

Yes, exactly.

[Neil deGrasse Tyson]

Nothing in quantum physics makes sense.

[Brian Greene]

And nothing in experience suggests there's anything but one single definite reality. And that was a conundrum. Experience shows one reality. Quantum mechanics speaks of many possibilities, measurements in that realm.

[Chuck Nice]

Right.

[Brian Greene]

That's right. So measurements, instruments in the realm of the small somehow seemed to pick out one singular definite reality. But here's the problem. When you look at the mathematics, which comes from Erwin Schrodinger, you can't transition.

[Neil deGrasse Tyson]

Cat fame.

[Chuck Nice]

Yes.

[Neil deGrasse Tyson]

Cat in the. In the Broadway musical I Think of Cats.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

That would have been really cool.

[Chuck Nice]

Well, there was. How do you know there wasn't?

[Brian Greene]

And this is the point. So Schrodinger's mathematics forbids a transition from many possibilities to the single definite outcome of experience. And so people said, maybe the transition never happens. And this is Hugh Everett, 1957, at Princeton. He looks at the equations and says, we are imposing a classical bias on reality. We think There's a single definite reality. But according to the math, if you look at that cat, there's one universe in which the cat's alive and you see it alive and you're happy. There's another universe where you see the cat dead and you're chagrined.

[Neil deGrasse Tyson]

Right?

[Brian Greene]

And that's the true reality. Neither of you knows about the other version of you. Each thinks they live in a single definite reality. But the bigger picture embraces more than one world.

[Neil deGrasse Tyson]

Was that other world always there, or was it created in the moment that

[Chuck Nice]

they had the, the realization of another realization? The realization of the.

[Brian Greene]

It's a really good and subtle question, and I don't think every physicist sitting in this chair would give you the same answer. As I look at the mathematics, I would say all those worlds, in a sense, are there. There's nothing really splitting, which is how we often describe it. The world splits into two. It's more that the description of the quantum realm allows his body language. Let me say some of that more.

[Neil deGrasse Tyson]

I know, I love that. Give me some more of that.

[Brian Greene]

The mathematical description now allows us to use the language of one world or another, when that language wouldn't have been applicable before your measurement. But it's not like the world splits and splits and splits. It's all sitting there in some giant uber realm.

[Chuck Nice]

Gotcha. So does the realization of the measurement. Are you saying that there's a possibility that you're not measuring a definite thing at that moment or instant? I'll call it in that instant. Or are you just seeing that and everything else is just still there, but, like, you can't see it because you're looking at this.

[Brian Greene]

See, it all depends on what you mean by you. And I hate to be so specific in the wording, because if by you, you have the conventional notion of a single human being, okay, each version of me does see a single world carries out a single measurement. It's just that if you had a God's eye view, which we don't have, you would see many versions of me with many outcomes.

[Chuck Nice]

Okay, that is so freaky, man.

[Neil deGrasse Tyson]

But it sounds like you just pulled that out of your ass.

[Brian Greene]

I, I, I didn't,

[Chuck Nice]

I assure you.

[Brian Greene]

All right, but that's an important point. Let me just emphasize that when Hugh Everett came up with this idea, it was the most conservative interpretation of the mathematics. Yes, it seems ridiculously uneconomical to have all these worlds, but the math, if you just take it at face value, this is what it seems to say.

[Sponsor/Announcer]

Startalk, radio, is supported by Claude from Anthropic Science isn't about rushing to conclusions, it's about sitting with the uncertainty until it starts to make sense. Claude is the AI built for that kind of thinking and anthropic committed to not running ads in Claude. So when you're chasing down an idea, there's nothing pulling you towards someone else's agenda. Try Claude for free at Claude AistaTalk and see why problem solvers choose Claude as their thinking partner.

[Chuck Nice]

T mobile 5G home Internet has some big news you should know about. They now have the fastest 5G home Internet according to the experts at Ookla Speed Test. Alright, so let's unpack that. It means photo backups happen faster. Streaming a documentary does install halfway through. What's really notable is that the jump in speed doesn't come with added complexity. Setup is simple. Plug it in and you're online in less than 15 minutes. And the value side of the equation holds too, with a plan price that's backed by a five year price guarantee. So if you want the fastest 5G home Internet with a simple setup and savings that stick, get t mobile 5G home Internet. And if you don't want that, wait a minute, why wouldn't you want that? Just visit t-mobile.com homeinternet to check availability today. Price guarantee exclusions like taxes and fees apply. Fastest based on Ookla Speed test intelligence data second half 2025. All rights reserved.

[Sponsor/Announcer]

This podcast is brought to you by Hotels.com make your next trip work for you. Hotel.com's new save your Way feature lets you choose between Instant savings now or Banking Rewards for later. It's a flexible rewards program that puts you in control with no confusing math or blackout dates. Book now at hotels.com Save youe Way is available to loyalty members in the US and UK on hotels with member prices. Other terms apply. See site for details.

[Chuck Nice]

Hey, this is Kevin the Sommelier and I support StarTalk on Patreon. You're listening to StarTalk with Neil DeGrasse Tyson.

[Neil deGrasse Tyson]

So let's back up. You and I have chatted, we've hung out socially, and you confided in me that when you were a kid and when you were in school, if you picked a book off the shelf and there were no equations in it, you immediately put it back.

[Brian Greene]

Yep.

[Chuck Nice]

Wow.

[Neil deGrasse Tyson]

Who does. Who does that?

[Chuck Nice]

I gotta say, who does that? Okay, a math teacher's favorite kid, that's who does that.

[Neil deGrasse Tyson]

Every math teacher's favorite student, teacher's pet in the Math class. So you have a math brain. You have a brain wiring where the math is clear and present to you more so than any words or descriptions that surround it. I don't have a problem with that. You are also dual professor at Columbia in physics and mathematics. What you just told me makes math the preeminent supreme account of reality. Because you're saying the math forces it. And I'm asking you, math is our tool. Why should math that you invented, you, anybody, humans force anything. Why can't I say there's a different idea that's gonna have different math that doesn't lead to that conundrum?

[Brian Greene]

So if you asked me that question 20 years ago, I would have given you one answer which would have been very combative. And I would have been defending mathematics as like, the deep truth of the world. In the past 20 years, I've shifted closer to your perspective. I really do see math as a powerful tool for describing the external world. I don't see it necessarily as the truth of what's out there, which is why I don't support the many worlds interpretation of quantum mechanics the way some of my colleagues do. I allow for it. It could be true, it's interesting, it blows your mind. But I do not say it's true because it comes out of the equations.

[Neil deGrasse Tyson]

Thank you. Okay.

[Chuck Nice]

Okay. That's a very. I'll say mature and advanced. That's right, very mature stance.

[Neil deGrasse Tyson]

You have matured in the past.

[Chuck Nice]

I have.

[Neil deGrasse Tyson]

Because I don't. You know, I love me some math. Don't get me wrong. Not as much as you do. But when I look at Kepler, who was a mathematician, fundamentally, and he knew about the Platonic solids. Do you know about the Platonic solids?

[Chuck Nice]

I know that they're friends.

[Neil deGrasse Tyson]

Platonic friends, yeah. So you can, if you have polygons, which are flat shapes that have the same sides on them. So a triangle would be a polygon, a regular polygon, a triangle, a square, a hexagon, that sort of thing. Right. So if you ask, can you make solid objects with these as its sides?

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

There's only five.

[Chuck Nice]

Five poly five shapes that. Five shapes that do exactly that, where

[Neil deGrasse Tyson]

each side is the same polygon.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

Only five.

[Chuck Nice]

Right. And one of pyramid, definitely one's a soccer ball.

[Neil deGrasse Tyson]

No, soccer ball has two different kinds of shapes on it.

[Chuck Nice]

Oh, really?

[Neil deGrasse Tyson]

Yes, it does.

[Chuck Nice]

Oh, so they're not all the same. No, not.

[Neil deGrasse Tyson]

Check next time.

[Chuck Nice]

All right.

[Neil deGrasse Tyson]

But it is a way to tile

[Chuck Nice]

them so that you can do it.

[Neil deGrasse Tyson]

So one is a pyramid, another one is a Cube.

[Chuck Nice]

Cube, of course. Right.

[Neil deGrasse Tyson]

And then there's like three others given to me.

[Brian Greene]

Yeah. Dodecahedron. And I don't even remember the noiha.

[Chuck Nice]

Yeah. So.

[Neil deGrasse Tyson]

And there's another one. Okay. So now, Kepler, a mathematician, said there must be some divine reason for this. There's five of them, and we have six planets. There was Mercury, Venus, Earth, Mars, Jupiter and Saturn. So he said, wait a minute. If the universe is special and math is special, obviously they have to be connected. They must be connected. So he embedded these Platonic shapes in each other, circumscribing one around the other to see if that gave him the orbital distances of those six planets, because we have six planets. You have five separations between them. He thought that was amazing. So he spends 10 years doing this,

[Chuck Nice]

and then it was over. He was like, I've wasted my. Oh, God, what have I done?

[Neil deGrasse Tyson]

But the math is what took him there. The beauty of the math. Yeah. And so that was my lesson that, you know, I ain't going there.

[Brian Greene]

But it goes the other way too, right? Because you go back to, say, George Lemaitre.

[Neil deGrasse Tyson]

So he's a priest, a Belgian priest. Yeah, yeah.

[Brian Greene]

He's studying Einstein's mathematics, finds that the equations. The math says that the universe should be expanding or contracting. He goes to Einstein, and Einstein says, your calculations are correct, but your physics is abominable. This math is not relevant to the world. It's like the Platonic solids. You're wasting your time. And yet in this case, Einstein was wrong.

[Chuck Nice]

Oh.

[Brian Greene]

Einstein's math was relevant in the way that George Lemaitre was suggesting. The universe is expanding. So you have to go.

[Chuck Nice]

Einstein didn't even know his math was relevant.

[Neil deGrasse Tyson]

Yeah. So. Yeah, so. So Lemaitre, he used calculations of Einstein's equations to force upon him a feature of the universe that not even Einstein was imagining.

[Brian Greene]

Exactly. Right.

[Neil deGrasse Tyson]

So that's math being bad.

[Chuck Nice]

The math discovered that.

[Neil deGrasse Tyson]

The math discovered it.

[Chuck Nice]

Yeah.

[Brian Greene]

So it's all just to say that it has to be case by case.

[Neil deGrasse Tyson]

You got me. You got me there. Okay. So now if everybody's doing these quantum physics experiments all over Earth and in all alien planets, is this a countable number of worlds?

[Brian Greene]

Yeah, that's a tough, tough question. It's infinite in any reckoning. But exactly which kind of infinity? We kind of understand it because we don't want to go into the deep mathematics, but there's a whole structure due to David Hilbert, a mathematician who actually raced Einstein to the finish line in general relativity, did not know he Was on the track. Yes. In fact, he published general relativity a little bit before Einstein did. Oh, there's a little known fact.

[Chuck Nice]

That must hurt. What's his name again?

[Brian Greene]

His name is David Hilbert.

[Chuck Nice]

Damn.

[Brian Greene]

And the thing that Hilbert.

[Neil deGrasse Tyson]

Because it's Hilbert space.

[Brian Greene]

Hilbert space.

[Neil deGrasse Tyson]

Tell me about that in a minute.

[Brian Greene]

But in this particular story, Einstein had visited Hilbert in June of 1915, showed him everything that he'd worked out for 10 years. Then Hilbert took it the final step and published before him. In the end of the day, Hilbert said, no, no, it's your theory, it's your theory, Albert. I, I'm not trying to take it

[Chuck Nice]

from you, that's very cool.

[Brian Greene]

But he did publish a little bit before him. Yes.

[Neil deGrasse Tyson]

Even though he would not have published had Einstein not at him.

[Brian Greene]

Yeah. He wouldn't have known anything. But the point for quantum mechanics is that there is this thing that you made reference to Hilbert space, which is the mathematical structure within which all these worlds live. And we understand the math of that pretty well.

[Neil deGrasse Tyson]

I know that.

[Chuck Nice]

Yeah. Yeah.

[Neil deGrasse Tyson]

So why does it need a mathematical structure in which they live?

[Brian Greene]

Well, if you're going to describe things with rigor mathematically, you've got to define things, you've got to have the operations to be able to categorize the ingredients. And remarkably, this space that Hilbert introduced has just the right mathematical properties to be the space in which all these worlds live.

[Neil deGrasse Tyson]

Does it suffer from an incompleteness feature?

[Brian Greene]

You know, every state completeness theorem. Yeah. Girdle.

[Chuck Nice]

Girdle.

[Brian Greene]

Yeah. So, so, so, yeah. So Girdle had a very powerful result that any basically sufficiently complex mathematical structure will have true statements that can't be proven true within the axioms of that structure itself.

[Neil deGrasse Tyson]

So it just has to be asserted.

[Brian Greene]

It has to be asserted or you have to somehow intuit it or feel it or in, you know, in the

[Chuck Nice]

general relativity sounds a little suspect.

[Brian Greene]

But the deep question is, are there interesting physical features of the world that would be undecidable in this Gordelian sense?

[Neil deGrasse Tyson]

That's what I'm asking you. So is there a feature.

[Brian Greene]

I don't know the answer.

[Neil deGrasse Tyson]

General relativity, where you part the curtains enough and then there's just some assumption you had to make.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

And everything issues forth from that that you cannot deduce from anything that follows.

[Brian Greene]

Yeah, I mean, there certainly are axioms within these theories for sure. But are there then deductions that are true but can't be proven within the structure itself? I don't know. Because when you look at Godel's proof The kinds of things that are undecidable are very contrived, you know, with things like, you know, the set of all sets that are not subsets of themselves. You're like, well, does that ever come up in the. In the real world, you know, or the Barber of Seville, you know, nobody shaves themselves, but then like, who shaves the barber? Who's, you know. So they're all very self referential and it's not obvious that they have direct relevance to things that we could measure,

[Neil deGrasse Tyson]

but it's still an important discovery.

[Brian Greene]

Hugely important. Yeah, hugely important.

[Neil deGrasse Tyson]

And this thing about the bar, the closest I got to that barber question was I used to read brain teaser books when I was a kid.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

And so one of them was, you come to a town, only two barbers.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

And one of them's just completely messy. And the guy's unkept and he's got. And his hair all.

[Chuck Nice]

But the town looks amazing.

[Neil deGrasse Tyson]

Wait, and there's another barber where he's clean shaven, he's. Everything's neat. So which barber do you go to?

[Chuck Nice]

I'm going to the messy one because he clearly does the other bar. Exactly, exactly.

[Neil deGrasse Tyson]

Somebody cuts.

[Chuck Nice]

That's the guy.

[Neil deGrasse Tyson]

That's the closest I've gotten to the barber. So with the many worlds now, connect that up to a multiverse. It's just a declaration. It's a multiverse of a kind.

[Brian Greene]

It's one flavor of multiverse that comes directly from the math of quantum mechanics. And the natural next question is, can you prove it? Can you demonstrate it?

[Neil deGrasse Tyson]

It feels less real to me than other multiverses I've read about.

[Brian Greene]

Yeah, no, I understand that feeling. Because our consciousness feels sing. And this theory is saying there are many individuals in this larger realm that have your memories, that have your experiences, and they only differ from you. That they saw the cat dead and you saw the cat alive in some universe, in someone. Yeah.

[Chuck Nice]

Now let me ask you this with respect.

[Neil deGrasse Tyson]

How do we act to this? Give me a second to like, all right, just tear up.

[Chuck Nice]

See, I watch a lot of Rick and Morty, so this doesn't bother me.

[Neil deGrasse Tyson]

Doesn't bother me at all. Of course it works that way. Duh. But this other me, that's me, identically, except we observed a different outcome of the experiment.

[Brian Greene]

Yeah. And then from there you continue to diverge. Because we know that little changes right now over time can turn into major deviations in your lives later on.

[Neil deGrasse Tyson]

Because I've seen in several films. But let me pick one specifically. H.G. wells, the time machine. I didn't read the novel, but I saw the movie, when is it from? The 60s. And the guy, the main protagonist, befriends a woman who, shortly after they have this encounter, she's hit by a truck. And he says, well, I have a time machine. I can go back and fix this. He goes back and says, oh, don't exit the part this way, go the other way. She goes the other way and something else hits her and she dies.

[Chuck Nice]

And the safe drops on her head when anvil. Right. And that, even better.

[Neil deGrasse Tyson]

And so after two or three iterations of this, or in another one, she's mugged and killed. He concludes that it was just her time, and he can't change fate, can't change the outcome. Okay, but when I saw that, I said the molecules of air that are around her are in a different place. Cause she's displacing these molecules relative to these. That's a different universe. I'm not gonna look at these as just. This is the only thing that has to stay constant. Tell me about all the other little things that change relative to the big thing that you notice.

[Brian Greene]

Yeah, so in that version, I think you're right. You know, if the person could really go back in time, change things, I think you would get a different universe. I don't know of any uber law that says certain major events or minor events have to be preserved. But in the quantum mechanical version, it's completely different. If you take on board this idea, you are committing to different worlds where things are radically different.

[Chuck Nice]

No matter.

[Brian Greene]

One she would live, and the other she would die. If they are allowed, if these outcomes are compatible with the laws of physics, then they will happen in one or more of the worlds in the quantum mechanical multiverse.

[Chuck Nice]

Wow.

[Brian Greene]

All. All things compatible with the laws of physics are real.

[Neil deGrasse Tyson]

Wow.

[Chuck Nice]

That's pretty wild, man.

[Neil deGrasse Tyson]

Okay, so, so. But all right, I love that. Wait, wait, stop.

[Chuck Nice]

I love that. Here's the only thing that I can't get with that. All right, in that case, how do you reconcile infinity or an an infinite number of worlds?

[Neil deGrasse Tyson]

Let me get there. So, okay, so watch. We went from the many worlds hypothesis where it is exactly me, but I look at a dead cat instead of a live cat, or vice versa. In the multiverses to which I've grown accustomed, there's possibly an infinite number of them, but maybe in one of them I am there mostly myself, except I have a goatee or I'm evil Neil instead of friendly Neil. So that's not the world's Neil.

[Chuck Nice]

You're Neil who believes in tarot cards.

[Neil deGrasse Tyson]

Well, so that's not a many worlds, Neil. That's just another statistically configured Neil out of the random molecules in that universe.

[Brian Greene]

Right. But the beautiful thing about the quantum mechanical multiverse is that when you study the possible worlds that can emerge, they embrace effectively anything that would have a non zero chance of occurring.

[Chuck Nice]

Okay.

[Brian Greene]

And that's anything, in effect, that's allowed by the laws of physics. So if the laws of physics allow you to have a goatee, then there will be a world in the many worlds where you do have a goatee.

[Neil deGrasse Tyson]

Right. But in that world, that's a different me looking at the cat, because the dead cat, live cat version of me, they each have a goatee.

[Brian Greene]

Yes. So if it's a very minor event, like doing a single observation. Usually a single observation can't yield such a radical change immediately. It'll be you without a goatee and one, you without a goatee and another. But then if you wait long enough and you accumulate the huge number of ways that you could have gone left, you could have gone right, you could have gone up, you could have said yes, you could have said no. When you put all those pepperoni. Yeah. Now, one of them results in you having a goatee, because that came along for the ride in that particular.

[Chuck Nice]

So here's what I want to know. Back to the infinity.

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

Are there a finite number of particles in this universe?

[Brian Greene]

There are finite number of particles in the observable universe, but the universe could go on.

[Chuck Nice]

It could go on forever. Okay. Then that, that beyond the horizon.

[Neil deGrasse Tyson]

We don't know.

[Chuck Nice]

Because my point is then that means there's a finite combination of all these particles that could create these worlds. And so how do you get to infinity? But if the universe goes on and on and on, then. Yeah, yeah, yeah. There is no or. There's no end.

[Neil deGrasse Tyson]

But even with an infinite number of universes with the same number of particles, you just configure them and keep reconfiguring.

[Chuck Nice]

My point is this. Can you reconfigure a finite number of particles?

[Brian Greene]

Yeah.

[Chuck Nice]

To get to infinity?

[Brian Greene]

You can't, because it's not reusing the same electron or the same proton in one world and another.

[Neil deGrasse Tyson]

Okay.

[Brian Greene]

It's a realization of that particle in a different configuration.

[Neil deGrasse Tyson]

Right.

[Brian Greene]

And. And that's. So there's not like a conservation of particle numbers.

[Chuck Nice]

Wow.

[Neil deGrasse Tyson]

So I used to be into. I used to be into big numbers, and I still am, but I haven't stayed with it. And one of My favorite big numbers was Skew's number. Do you know Skew number?

[Brian Greene]

I don't know skew's number.

[Neil deGrasse Tyson]

10 to the 10 to the 10 to the 34th power.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

And if you. If you play that out.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

You get the total number of configurations of all the particles in the observable universe. Right. So it's as though if the universe were a cosmic chessboard, it'd be the total number of possible moves.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

Because you're not counting objects at this point. You're counting events. You're counting things.

[Chuck Nice]

Combinations.

[Neil deGrasse Tyson]

Combinations.

[Brian Greene]

Yeah. I would get a different number. If I was to use the entropy of the observable universe, which we can calculate from the dark energy. I would get a 10 to the 10 to the 120. Okay.

[Neil deGrasse Tyson]

Is that much?

[Brian Greene]

Yeah. So I think it has to do with whether you're only looking at material particles that.

[Neil deGrasse Tyson]

Yeah, yes. Yes, it is.

[Brian Greene]

Versus the energy that.

[Neil deGrasse Tyson]

Oh, no, of course. Yeah. The energy is all in there too.

[Chuck Nice]

Yeah, yeah, yeah.

[Neil deGrasse Tyson]

This is just counting up the. The physical particles.

[Brian Greene]

Sure. That makes sense.

[Neil deGrasse Tyson]

Okay, cool.

[Chuck Nice]

So do we. Do we actually know the amount of. Of dark energy that's in the universe?

[Brian Greene]

Well, we measure it.

[Chuck Nice]

We do measure.

[Brian Greene]

We do measure it by the rate at which distant galaxies are accelerating away from us. Exactly. And it's this ridiculously small, small number.

[Chuck Nice]

Okay.

[Brian Greene]

In the units that we typically use to measure these things. And that translates into this particular number for the entropy, the number of states that the universe can possibly be found in.

[Chuck Nice]

Right. Okay, that makes sense.

[Brian Greene]

But the question you asked before, if we could return it for a second, because it is issue. This issue of infinite number of worlds.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

Wait. But just before you get there, I just want to remind people that when you say if there's a chance something can happen, no matter how small.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

You multiply that very small number by infinity and you get a.

[Brian Greene]

You get a real number and you get many worlds. You get many in which that could. That small probability thing could happen.

[Neil deGrasse Tyson]

Exactly. So the. The infinity that you're. Where you're about to go.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

Helps bring out of the. Out of the depths the statistically unlikely possibilities.

[Brian Greene]

And that, to me, is the Achilles heel or a potential Achilles heel of this approach. And again, I have to say, different people in this chair, they will different things. But the issue that many of us have taken with the many worlds is just that if an outcome has very small probability. Right. That should mean it's very unlikely to happen. But from the analysis that you just gave, no matter how unlikely it is to happen. It will be realized in some world. So what does it mean to say something is unlikely if you're sure it's going to happen in some world?

[Chuck Nice]

Exactly. It's like having a drink. I think it's five o' clock somewhere.

[Neil deGrasse Tyson]

So we encounter this in astrophysics where we talk about supernovae as being an extremely rare event. Okay. Not all stars will go supernova, and even high mass stars, some go black hole. It's rare. However, the galaxy has 100 billion stars in it. There's 100 billion galaxies in the universe. So when people realize if you have enough of a sample size, you could deliver every single night supernova into your catalog.

[Brian Greene]

Right.

[Chuck Nice]

It's a rare event. That happens often.

[Neil deGrasse Tyson]

Yeah, exactly. So that was initially kind of hard to explain to the public how you get that.

[Brian Greene]

Yeah. So we have a version of that in the quantum mechanical multiverse, but it is more of an issue because you're guaranteeing the existence of a world, a whole world filled with observers and experimenters who are guaranteed to see the most unlikely things on a regular basis. And that is an issue. Now, there are some people who work on this who say, we've solved that. Just read our paper, read our book, and they do some interesting mathematics. I am not convinced. And that, to me, is where the issue is.

[Neil deGrasse Tyson]

Okay, interesting. So let me ask. I think we chatted about this over lunch a few moons back.

[Chuck Nice]

Thanks for inviting me.

[Neil deGrasse Tyson]

Oh, it's in your inbox.

[Chuck Nice]

I missed that.

[Neil deGrasse Tyson]

And forgive me, I might have had this conversation with Brian Cox. So I'm sure.

[Brian Greene]

Yeah, yeah.

[Neil deGrasse Tyson]

Forgive me, because you're my favorite physicists out there. So. But. So do you feel bad that I have another physicist who I.

[Brian Greene]

A little bit.

[Neil deGrasse Tyson]

So I happened. I learned this early because I said I was into big numbers when I was a kid, that there are levels of infinity.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

I think they're at least five.

[Brian Greene]

You can keep on going.

[Chuck Nice]

You buried the lead, guys. Now, you got to explain that. You can't just say that you weren't at the lunch, that there are levels of infinity.

[Brian Greene]

Yeah, yeah, yeah, yeah.

[Neil deGrasse Tyson]

But you weren't at the lunch.

[Chuck Nice]

You know how counterintuitive that is.

[Neil deGrasse Tyson]

I know you weren't at the lunch, so should. Do I have to drag you behind us?

[Chuck Nice]

I know, man. Listen, I'll take a doggy bag. Okay. Because that's crazy what you just said.

[Neil deGrasse Tyson]

We'll get. We'll explain that in a minute.

[Chuck Nice]

All right, Go ahead.

[Neil deGrasse Tyson]

So I kept thinking to myself that. That you can have an infinity of Universes. And that would not be a big enough infinity to exactly reproduce me. And that you would maybe need at higher levels of infinity to get all the combinations that people like to talk about in the multiverse.

[Brian Greene]

Right, right.

[Neil deGrasse Tyson]

So does it require the higher levels of infinity?

[Brian Greene]

You know, the most straightforward answer would be to say I don't fully know because I don't know that science understands you, and by you, I mean life well enough to say, you know what you just said?

[Neil deGrasse Tyson]

He said I could be so simple. It's right trivial to copy under no

[Chuck Nice]

obligation to understand you.

[Brian Greene]

But, but, but if you take on board the idea that you are just a collection of particles that are governed by the quantum mechanical laws, if that is something you're willing to accept, then there is enough room inside of, you know, Hilbert space in the quantum mechanical infinity to reproduce you and to reproduce every variation on you where some of

[Neil deGrasse Tyson]

your particles variation conceivable.

[Brian Greene]

Yes, yes. Every variation allowed by the quantum laws, which simply.

[Neil deGrasse Tyson]

Listen to me, that has a tooth cavity because I've never had a cabinet.

[Brian Greene]

If that's compatible with the laws of physics, and I think it is, then yes.

[Chuck Nice]

So non dental plan, Neil. This is the Neil with no dental plan. If that's within the bounds of quantum mechanics, of physics, don't prevent it, then we got enough. We got enough mat not matter. We have enough material to make sure

[Neil deGrasse Tyson]

that I don't need the higher levels of infinity.

[Brian Greene]

No.

[Chuck Nice]

Okay. Absolutely.

[Neil deGrasse Tyson]

Okay, so now let's, let's catch up, Chuck, because everyone else out there knows about multiple infinities, so

[Chuck Nice]

please catch me up.

[Neil deGrasse Tyson]

So these are levels of infinity. I think there's a Hebrew letter associated.

[Chuck Nice]

Aleph.

[Neil deGrasse Tyson]

0 is a traditional infinity. Aleph, 1, 2, 3. So we don't have to do all five. Just get me to like the second infinity.

[Brian Greene]

Yeah. So the simplest one is the one that comes to mind immediately. You just count the numbers 1, 2,

[Chuck Nice]

3, and they just go on.

[Brian Greene]

And they just go on. And that's the simplest straightforward. But then if I ask you, how many numbers are there between 0 and 1 on the number line?

[Chuck Nice]

Oh, wow.

[Brian Greene]

Now you say to yourself, well, can I enumerate them? Can I put them into a correspondence with the counting numbers and just list them?

[Neil deGrasse Tyson]

Because if you cross, however.

[Chuck Nice]

But am I not. But I'm still going towards it, aren't I dividing then when I go in between numbers? Yes, I'm kind of dividing.

[Brian Greene]

You are. And you could say, well, let me put a dot in the midpoint, call that one, and then a dot in the midpoint between it and zero and call that two. You won't cover all the numbers. And, and there's a wonderful.

[Chuck Nice]

I'll never reach one because there'll always be a place where I can once again put something in between one and where I am.

[Brian Greene]

It's another way of saying it, but Cantor had a powerful argument that's actually pretty easy to understand. We'd need to write it out for me to show it to you. But he established that if you try to enumerate the numbers between 0 and 1, just list them, you will fail. You will always miss some. And therefore there are more than an infinity of numbers between 0 and 1. And that next level of infinity is the version that Neil was referring to. Yeah.

[Chuck Nice]

Alice, give me my bag, I'm gonna need my weed.

[Neil deGrasse Tyson]

Okay, so you just skipped by it, and I want to make sure we can contemplate it briefly. The one way to know which infinity is bigger than the other is you correspond them to each other.

[Brian Greene]

Yes, exactly.

[Neil deGrasse Tyson]

Right. So you can say, because this is kind of a little freaky, the odd numbers is the same size infinity as all the counting numbers that include odd and even numbers.

[Brian Greene]

Of course.

[Neil deGrasse Tyson]

Now how do you, how do you get that?

[Brian Greene]

Well, you know, you could take any given number and say, multiply it by two and add one to it. And in that way you're certain to

[Chuck Nice]

get an odd number.

[Brian Greene]

You get an odd number, and now you've lined up, you've lined up the numbers 1, 2, 3 upward, and the list that it corresponds to are all odd numbers.

[Neil deGrasse Tyson]

They all just go up.

[Brian Greene]

Yeah.

[Chuck Nice]

Damn, that's wild. Wow. Math is kind of cool.

[Brian Greene]

Yeah.

[Chuck Nice]

Who knew?

[Neil deGrasse Tyson]

Okay, and, and, and just to taste it, if I remember correctly, Aleph 2, does it go into another dimension? The number of lines in three dimensional space is a bigger infinity than the counting numbers on a number line.

[Brian Greene]

Yeah, that may be a way of saying it. I'm not sure. There are many ways of expressing these infinities, and there's actually a kind of almost an algorithm that allows you to start to build up, up this set of infinities. You can look at subsets of subsets and things of that sort, look at power sets, as it's called. And so it's a astoundingly strange idea, which is why mathematicians who thought about this in the early days, you're all

[Neil deGrasse Tyson]

in asylums right now.

[Chuck Nice]

Yeah, I'll never get to one. I'll never get to one. I'll never get to one.

[Neil deGrasse Tyson]

I'll never get to one. That is so rude. And if you go to higher dimensions in principle, does that take you to not necessarily infinities?

[Brian Greene]

No, I mean if you start to look at the number of points in the plane, points on a line versus points in a plane. So you have to be fairly sophisticated in how you build up these infinities. But for our purpose, there is this thing that we've made reference to, it's a bit abstract, this thing called Hilbert space. And we understand it reasonably well. It's an infinite dimensional space that David Helbert developed. But we understand it well enough to say it does have enough room to embrace all the quantum mechanical states.

[Neil deGrasse Tyson]

It's infinite dimensions. You think it has enough room.

[Brian Greene]

And within that space in principle, there is a place that describes you.

[Neil deGrasse Tyson]

All right, so now I am however, improbable in the configuration of atoms and

[Chuck Nice]

molecules, even here in this actual reality.

[Neil deGrasse Tyson]

Okay, so have you thought much about whether or not something can exist and whether or not it does the likelihood of things?

[Chuck Nice]

Yeah.

[Brian Greene]

And it's a mind blowing thing. Tell me when you think about the sequence of steps by which you came to be, and I'm saying let's go to your childhood, to your birth, let's keep on going further back your grandparents grave, let's go all the way back to the Big bang. And if you look at the sequence of steps from the Big Bang.

[Neil deGrasse Tyson]

Go back to the big Bang.

[Brian Greene]

You do actually, we all do.

[Neil deGrasse Tyson]

Right. That's how we get here.

[Brian Greene]

You know, we have collections of particles that are configured in a certain way and they have a history. And it's that history which resulted in them being in the configuration that's called Neil Degrasse Tyson. And if you look at the sequence of quantum steps, each of them are incredibly unlikely. And the collection of those sequences is innumerably huge and therefore incredibly unlikely. And yet here each of us are.

[Neil deGrasse Tyson]

So what do I do with this information?

[Brian Greene]

Well, I think it gives you a sense. Well, you know, there's. If you wanted me to be a little bit sappy.

[Neil deGrasse Tyson]

Yeah.

[Brian Greene]

You know, I think it inspires a gratitude, the unlikeness of us being here against being at all. And therefore is a certain kind of thankfulness that the universe just turned out in a way that gave us a brief moment to stand up, look around and appreciate everything that's wild.

[Chuck Nice]

So now I'm looking at that and immediately going back to our previous conversation about the two observers, okay. With the dead cat, the dead cat, live cat and the. And the many worlds. What you just said can negate that. Meaning that also there are an infinite number of worlds where there's just no Neil. And then there's an infinite number of worlds where there is no cat and then there's an infinite number.

[Brian Greene]

You, you know, you're absolutely right. And I think that's one of the lessons. If you take the many worlds approach to quantum mechanics to heart. It is saying that clearly we are compatible with the laws of physics because we're here, existence proof.

[Chuck Nice]

Right.

[Brian Greene]

And if you take the many worlds seriously, then we were guaranteed to live in some world in this grand collection of many, many worlds. Now, in some sense, this world is incredibly unlikely within the panoply of possibilities. But you're right in that sense, we were an inevitable outcome of the quantum laws because we are allowed by those very laws of physics.

[Chuck Nice]

Okay, Right.

[Neil deGrasse Tyson]

But Brian, I have a more anchored version of what you just said that I, that I credit to Richard Dawkins.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

If you look at the total possible genetic combinations that will make a human being a viable human being.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

It's a stupefyingly large number, like 4

[Brian Greene]

to the 3 billion or something. Right.

[Neil deGrasse Tyson]

10 to the 30th power. It's high. What matters is not even how big it is, but it's vastly larger than the total number of people who have ever been born.

[Chuck Nice]

Right. Yeah.

[Neil deGrasse Tyson]

Which plus or minus, it's about 100 billion. Okay. So Dawkins point is we should cherish life because most people who could ever exist will never even be born.

[Chuck Nice]

That's right.

[Brian Greene]

Yep.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

So we can be sad that you die, but he describes those people who die as the lucky ones who got

[Chuck Nice]

to live in the first place, because

[Neil deGrasse Tyson]

you can only die if you got to live.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And for me, that's a little more anchored than.

[Brian Greene]

Yeah, but to take the point we were saying before, if the multiverse version of quantum mechanics is the right way of thinking about it.

[Neil deGrasse Tyson]

They did.

[Brian Greene]

Then. They did live if. If their genetic sequence was compatible with the law of the physics.

[Chuck Nice]

So, you know, so don't feel bad for all those little swimmers that didn't quite make it to the egg,

[Neil deGrasse Tyson]

The sperm you're talking about. So, Brian, I get this question often. Surely you do as well. If we live in a multiverse and we're just one of an infinitude, where are the other universes?

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

And you're going to cop out and say, oh, they're in the infinite dimensional Hilbert space.

[Brian Greene]

Well, it's easier to answer that question for other flavors of multiverse, like the inflationary multiverse that you made Reference to before, because that's the simplest, that's the simplest one to picture.

[Neil deGrasse Tyson]

So those are other places within our own. We're in a bubble.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And there's another bubble over there in the same sort of space time.

[Chuck Nice]

Construct.

[Neil deGrasse Tyson]

Construct.

[Brian Greene]

In the same construct, yeah. Because according to inflationary cosmology, as you're making reference to, there was, was an energy field that gave rise to repulsive gravity that drove our Big Bang. But the math shows that it would not have used up all of that energy in the process. Some would be left over. The leftover energy would yield another Big Bang and it would not be fully used up, yielding another Big Bang. And so these distinct Big Bangs, as you say, would give rise to these sort of bubbles in a big cosmic bubble bath.

[Neil deGrasse Tyson]

Okay, so that's in one construct.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Okay. But now, now there are other variants, multiverses, where it's sort of separate.

[Brian Greene]

Yeah. When you talk about the quantum mechanical multiverse, it's much harder to think about where those other worlds are. They're not kind of adjacent to our space. It's a more abstract place that they inhabit. And I'm going to try to avoid using the word Hilbert space, but that's the mathematical architecture within which we can, can see these worlds existing. I can't picture, I can't picture where these other worlds are. If you ask me, do I have a mental image of them? Not really.

[Neil deGrasse Tyson]

Okay, so that's a mathematical architecture. Can I divine an experiment that would show that they exist? Can I wormhole to them?

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Do I even want to wormhole to them? Because quantum physics might give you slightly different laws of physics.

[Brian Greene]

It's unlikely the laws of physics are different, but the properties of ingredients might be different in principle, if there are some sufficient quantum mechanical processes that could yield worlds with those distinctions. But I don't know of an experiment and I don't think anybody does. Where, when you can say if we could get this and this result, we would establish that the multiverse is true,

[Neil deGrasse Tyson]

that other universes, gravity can leak out of them.

[Brian Greene]

Yes. So that's another variation on the multiverse that comes from string theory, which we can talk about.

[Neil deGrasse Tyson]

We'll get there.

[Brian Greene]

Yeah. But just to presage what we might talk about in this version, our universe is sort of like one piece of bread in a big cosmic loaf. And the other slices of bread would be the other universes. So they would really be hovering next to us, just displaced in an actual additional dimension of space. And then you're right, gravity can influence permeate that space.

[Chuck Nice]

So when I was having my little ayahuasca trip, I met these beings that were in betweeners and they were in between dimensions. That's where they occupied. Okay, I feel so silly, but we're listening. Okay. They explained that they talked to you. They did, they talked to me. And they were two dimensional beings that I could see in 3D. Sounds creepy, but that's the only way I can explain it. Okay. And they explained to think of it like an infinite number and they call them dimensions, going out and going up and going out, but to think of them as a deck of cards slapped up the way we see a deck of cards, we see it as one deck of cards, but it's not, it's however many cards are in that deck.

[Brian Greene]

Right.

[Chuck Nice]

And until you separate them, that's when you can see the different things. That's how it was explained.

[Brian Greene]

So this is almost the reverse of that. It's as if we only see one card in the deck. That's our world. But a God's eye view would see the entire deck which would have the other cards.

[Chuck Nice]

And that's who, that's where they see. They, I see it as the one card and they were explaining that they see it as the deck. But anyway, I'm just, I, I, I had shared that with Jan11 and she was like, that's pretty interesting because. And then she gave me some speak that I didn't understand.

[Brian Greene]

Yeah, it must be the same basic idea. Actually we just wrote a paper on these so called brain worlds in, in string theory. So this is something short for membrane. Membrane. Should have said that.

[Neil deGrasse Tyson]

Thank you.

[Brian Greene]

So these ideas, these are universes that are like a membrane and there can be multiple membranes which would be multiple worlds. And in principle, as Neil was mentioning, they can influence each other. Gravity from one can influence in the other.

[Neil deGrasse Tyson]

So I never took, I'm saddened by this. In graduate school I'm taking astrophysics classes, but I wanted to take more physics and a physics class I never took was, is field theory. Yeah, a whole course on field theory.

[Brian Greene]

And you can come to my class. One of these. Yeah, I've taught field theory a number of times. Yeah, I'll let you know next time. Excellent.

[Neil deGrasse Tyson]

I sit in the back.

[Chuck Nice]

That's not intimidating. I'm gonna fail.

[Neil deGrasse Tyson]

No, but I, I'm not in a position to calculate or even really know why. Gravity can escape, but not the electromagnetic.

[Brian Greene]

Well, I can give you a quick mnemonic sort of to think about, which is. So in string theory, gravity is communicated By a string that has no ends. It's a closed loop.

[Neil deGrasse Tyson]

Okay.

[Brian Greene]

The electromagnetic force is communicated by photons, which in string theory are strings that have two open ends, and those ends are anchored to the membrane. They can't escape the membrane. But because the gravity particle, the graviton, has no ends, just a loop, it's not anchored. It can get off and travel between those worlds.

[Neil deGrasse Tyson]

Is that a description that would be in the book String Theory for Dummies.

[Brian Greene]

It's there, no doubt.

[Neil deGrasse Tyson]

Okay, so if that's the case, why isn't what we measure as dark matter just gravity leakage from another slice of bread?

[Brian Greene]

People have made proposals like that. If you're. Dark matter is meant to explain the gravity that we know is there.

[Neil deGrasse Tyson]

Dark gravity.

[Brian Greene]

Dark gravity, yeah. So if you can have some source of gravity that you don't literally see, it's a candidate. And so people have put forward. It's hard to make this idea really work, but in terms of its general possibility. Sure.

[Neil deGrasse Tyson]

Because the betting person's. You know, if you're into betting what an outcome would be, an exotic particle is sort of the betting man's solution to. But that's put forth by particle physicists.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

You know, if you're a hammer, you're

[Chuck Nice]

a little bit of bias.

[Neil deGrasse Tyson]

Right? A little bit of bias. Right. So I'm liking me the, you know, this gravity spillage.

[Brian Greene]

No, I like the idea. It's in detail. It's only when you get down to brass tacks, it's hard to make this really work.

[Neil deGrasse Tyson]

All right, so let's pick up the baton here on string theory. Yeah. Okay. Where I'm a little older than you, but we. We came of age with enough overlap. So I can speak of the 1980s as a time time where string theory was birthed and started taking off with some vigor. Yeah. All right. Everybody I spoke to at the time, and at the time, I was at the University of Texas, which had its share of strength theorists.

[Brian Greene]

Yes.

[Neil deGrasse Tyson]

And Steve Weinberg.

[Brian Greene]

Steve Weinberg for sure.

[Neil deGrasse Tyson]

A graduate of my high school.

[Brian Greene]

That's true. That's true.

[Neil deGrasse Tyson]

Not your high school.

[Brian Greene]

Yeah, I agree.

[Neil deGrasse Tyson]

So Steve Weinberg, Nobel laureate in physics, cosmologist, you know, anyhow, so I asked people, so when are you guys going to figure this out? Because you're trying to unify quantum physics and the large and the small, and it's, oh, we're almost there. Five years. In five years, we think we'll do it. So, you know, 10 years later, well, when are you going to do it? Oh, in five years, 20 years later. Oh, in five years. The problem is hard. It's a hard problem, but we're on the. And so I've never heard convergence in any conversation about string theory landing where it had intended a B. Could it be, and I think I've said this on stage to you, and you didn't jump up and try to hurt me. Could it be that all of you are just too stupid to figure out the solution? And let me say that more charitably, are we awaiting the birth of some 21st century Einstein to see the solution here that none of the rest of you are?

[Brian Greene]

Yeah, yeah, it's all possible. First off, I would never have said five years back then. It's a very dangerous thing to make a prognostication of that. Yeah, there was huge enthusiasm. But look, string theory has done miraculous things since the 1980s, and I'm happy to sort of listen to the achievements, but you're right, it's not done. The one thing that ultimately matters, which is make a prediction that we can test, you know, at a particle collider and determine whether these ideas are correct. And it could well be that we just don't have the brain power to get there. And it may not be that we're awaiting the birth of the next Einstein. Maybe we're just awaiting the next configuration of AI that may be able to do what we as individuals have not been able to do. I do think there's a real, real possibility of the nature of research changing the next five to 10 years.

[Neil deGrasse Tyson]

In the next five years. You hear that?

[Chuck Nice]

Yeah, I did hear that.

[Brian Greene]

This one. This one I'm willing to stick with, though, because, you know, the. I gave you an example. I mentioned this paper that I wrote with Jana Levin that you make reference to.

[Neil deGrasse Tyson]

Is this the Loaf of Bread paper?

[Brian Greene]

No, it's just we wrote a handful of papers together. This is a more recent one. And I wondered, could. Could chat get the answer that took us a long time to get. If I treat. Chatgpt. If I treated it as sort of a good graduate student. So I just gave it a few prompts the way you would to a graduate student, did not give it the answer, and it couldn't look up the answer. We hadn't yet published a paper and within a half an hour it was able to reproduce the results that took us months to get.

[Chuck Nice]

Oh, my gosh.

[Brian Greene]

And so it's as if you have the greatest graduate student known to humankind, even an army of them, at your disposal. And that's.

[Neil deGrasse Tyson]

Now this is a hologram right now.

[Brian Greene]

You know, it's an AI. I'm not even here. So what is it going to be like in five years? You know, it's both exciting and scary.

[Neil deGrasse Tyson]

I have a colleague who has a similar story regarding his research where he was prompting chat to think about a problem.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

And it solved a problem that he could. He had not been able to solve.

[Brian Greene]

And actually solved it.

[Neil deGrasse Tyson]

Yeah, actually solved it. Wow. In the sort of. You prompt a really good graduate student in just the way you're describing.

[Brian Greene]

Right.

[Neil deGrasse Tyson]

But catch us up just on why the whole field is called string theory.

[Brian Greene]

Well, the basic ingredient is a filament that looks like a tiny piece of string. The idea is that it can vibrate in different patterns and the different particles that we know and love. Electrons, quarks, neutrinos, and so forth.

[Neil deGrasse Tyson]

Fundamental particles.

[Brian Greene]

Fundamental particles would each correspond to different vibrations, patterns of this new entity called the string.

[Neil deGrasse Tyson]

So the string becomes the fundamental particle.

[Brian Greene]

Yes. And it's a unity because it's one thing that can manifest as many different things depending on how it's vibrating, which

[Neil deGrasse Tyson]

is for people who like unity. This is a. This is a beautiful thing.

[Brian Greene]

It's a beautiful thing. And it goes even further. When you look at the math of this, you find that not only does it unify all the particles, but it unifies quantum mechanics and general relativity. The laws of the small and the

[Neil deGrasse Tyson]

laws of the big do that for free.

[Chuck Nice]

Free.

[Brian Greene]

It does that for free. It just comes out. I'm telling you, you look at the math.

[Neil deGrasse Tyson]

That's a nice fact.

[Brian Greene]

Let me. You know, you look at the math, right? You stare at the equations, and out pops Einstein's equations from general relativity.

[Neil deGrasse Tyson]

To whom does it pop? Who do you have to be for it to pop out? So I. I had not fully embraced that reality of string theory. So I'm delighted to hear that. So that. That was part of the enthusiasm that people would have then had.

[Brian Greene]

That was really the heart of it all.

[Chuck Nice]

The major obstacle.

[Brian Greene]

The major obstacle is that the theory is mathematically complex. And the pathway from the fundamental equations to physics we can see in the laboratory is fraught. It's difficult. It's tough terrain to cover. And so we've been developing mathematical tools to do that for now 30 years. We've made. Made progress on black holes.

[Neil deGrasse Tyson]

The 80s was 40 years ago.

[Brian Greene]

I guess you're right. Oh, my God. Strength there. Hasn't answered that question yet.

[Neil deGrasse Tyson]

Yeah, it's 40 years ago.

[Brian Greene]

40 years ago.

[Neil deGrasse Tyson]

40 years before that was the 1940s.

[Brian Greene]

Yeah, I'm with you on that.

[Neil deGrasse Tyson]

All right.

[Brian Greene]

You know, so we've been for 40 years trying, you know, and so we've understood things about space and time and. And gravity and black holes, which I didn't think we'd ever understand.

[Chuck Nice]

Right.

[Brian Greene]

In my lifetime.

[Neil deGrasse Tyson]

Yeah.

[Brian Greene]

On the flip side, though, we've not understood the things that I thought we would have understood by now, which would be make a prediction for what's going to happen at the Large Hadron Collider and let's check it. And so it's an interesting thing that we've made headway in the very things I thought would be too hard. And we've not made headway on the things that I thought we would be able to reach by now.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

So I don't like making arguments that other people make just for the sake of bringing the argument to you. But just let me just do that.

[Chuck Nice]

But let me do it anyway.

[Neil deGrasse Tyson]

Let me do it anyway. So string theory has not been without some criticism as something that has consumed the ambitions of graduate students and faculty and promotions. And so it's a field without a prediction that can be tested. You. Yet it had such a presence on the landscape of physics departments, it might have smothered some other branches of physics that might have been a little more promising. You just comment on that?

[Chuck Nice]

I sound like jealousy to me.

[Brian Greene]

Well, it's an interesting argument because the very graduate students and junior faculty and senior faculty who this person who's making this argument fears may have wasted their time not looking at something more promising. You gotta assume they're really smart people because they're the very people you think who could have pushed the frontier of another field. And if they're that smart, allow them to make the choice for where they think the greatest promise is. Yeah.

[Neil deGrasse Tyson]

Who are you to say that they're not gonna.

[Brian Greene]

So it's not as if somebody was like putting a bag over their head or, you know, putting a gun to. They were looking at the ideas that were out there, found the string theoretic ideas so compelling that they were willing to take a chance. And that chance may not pay off in our lifetime.

[Neil deGrasse Tyson]

And tell me about the 10 or 11 dimensions. Yeah, because that sounded very cop out. Y.

[Chuck Nice]

Well, you know, I can't explain this.

[Neil deGrasse Tyson]

Let me throw in a dimension.

[Brian Greene]

Ah, good.

[Neil deGrasse Tyson]

Another dimension.

[Chuck Nice]

Why do you need the dimensions? Good, good, good.

[Brian Greene]

And I think if I articulate this correctly, I think you'll have the same epiphany that you did about gravity coming out of string theory a moment ago. Because again you wondered, do you have to put general relativity into string theory? I said, no, no, it just comes out out for free, which is a beautiful thing. How about the extra dimensions? They come out for free too. They're forced upon you by the equations.

[Neil deGrasse Tyson]

You don't put them in.

[Brian Greene]

Not at all. The math does it for you, literally. This is not a joke. There's an equation in string theory that basically looks like D. The number of dimensions minus 10 times this complicated factor must be equal to zero for this theory to be self consistent. The complicated thing is never zero. Therefore D minus 10 must be zero. Therefore D must equal 10. That is where the extra dimensions are forced upon you by the equations.

[Chuck Nice]

That's insane. That's pretty cool though.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

And I mean that's so 10 dimensions. So we don't experience them. Why?

[Brian Greene]

Because we believe that they're probably too small for us to see with the naked eye.

[Neil deGrasse Tyson]

Or what does small dimension mean?

[Brian Greene]

It means that if you head off in a given direction, you kind of return to your starting place so quickly you can think about a straw. Right? A straw has a long dimension that we can easily see, but it has a curled up circular dimension. And if that circle, of course we can see that with the naked eye. But if you made that circle, there's liquid through it. Yes. But if you made that circle smaller and smaller and smaller, at some point you won't see it at all and you'll think it's just a line. You've hidden the extra dimension.

[Neil deGrasse Tyson]

So all the other dimensions are hidden.

[Brian Greene]

We think that is one explanation for why we don't exist.

[Neil deGrasse Tyson]

Can anything exist in those hidden dimensions?

[Brian Greene]

I was going to call the Elegant Universe Hidden Dimensions. That was the title I was playing with back, you know, 25 years ago. But anyway. Yes, exactly.

[Neil deGrasse Tyson]

All right. So you're hiding the dimensions from us.

[Brian Greene]

Yes. Okay, but now that is by hand. So when we look at the math, the equations don't tell us these extra dimensions are really tiny. Instead we're doing what you accused me of, perhaps on other things. We're saying, how can we make this theory compatible with what we see? Let's envision that the extra dimensions are really small.

[Neil deGrasse Tyson]

Got it? Okay. And so how. So A string is 10 dimensions.

[Brian Greene]

A string is living in a 10 dimensional space.

[Neil deGrasse Tyson]

Okay. Now why would a string be fundamental and not. Because a string is one dimensional. Yeah. And dimensions are just dimensions. Why can't there be another reality maybe in which we're embedded, where the string is not fundamental, but a plane is what's fundamental.

[Brian Greene]

Yes. And that's one of the developments in string theory itself. So when we talk about these membranes, the piece of bread or the card

[Neil deGrasse Tyson]

in the deck, string theory upped by

[Brian Greene]

a dimension, and string theory takes you there. It's not something, again, that you put in by hand.

[Neil deGrasse Tyson]

He goes wherever his equations want to take.

[Brian Greene]

I need to say this is a purely mathematical undertaking. Totally. You know, but the beauty of it is you don't put things in from the outside. You study the equations, and it takes decades sometimes, but you extract what the equations are trying to tell you.

[Neil deGrasse Tyson]

So before we go to queries, what is the current state of string theory?

[Brian Greene]

Current state is health. Yeah, I. You know, it's funny. I asked this question in a program to three string theorists, a World Science Festival program. I asked them, guys, grade string theory. How, you know, if string theory was a student, you know, how would you grade it? And the grades went from B plus. I think that may have been Nobel Laureate David Gross. I could be getting their grades wrong to an A, which was Andy Strominger, who's a string theorist at Harvard. And if you look at its theoretical insight into black holes, the mathematical insights that it's given started whole fields of mathematics. If you have any interest in the nature of space and time and what it might be made of, these are the kinds of insights that string theory is giving. So I'd say it's very healthy, but it has not made a prediction, allowing us to determine whether it's correct.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

And that's almost a violation of one of the most important tenets of a. Of a viable theory.

[Brian Greene]

Yes. And that's why maybe you shouldn't call it string theory.

[Neil deGrasse Tyson]

Oh, what should we call it?

[Brian Greene]

Yeah, maybe call it the string hypothesis.

[Neil deGrasse Tyson]

Okay.

[Brian Greene]

Theory really should be reserved.

[Neil deGrasse Tyson]

That's a more humble.

[Chuck Nice]

Yeah, but the math makes it a theory.

[Brian Greene]

Well, no, no, no.

[Neil deGrasse Tyson]

For a theory to be a bona fide theory, it's got to not only account for what you see.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

Or in an organized, coherent way, it's got to make predictions that. That you have verified.

[Chuck Nice]

Right. You got to be able to. You got to be able to measure, predicted.

[Neil deGrasse Tyson]

Then it's only one half of what's going on. And. And it.

[Brian Greene]

Yeah, so we're using the word wrong, and I agree with people who are sticklers on that.

[Neil deGrasse Tyson]

Got it.

[Chuck Nice]

But is that because, And I don't want to sound like a, you know, a jackass, but what you just explained, I, I gotta say, like, Einstein had it easy. I mean, I'm serious.

[Brian Greene]

Yeah, right.

[Chuck Nice]

Like, Einstein had it easy compared to what you're just talking about.

[Brian Greene]

I agree. He wrote down his equations, and within a handful of years, you could test it.

[Chuck Nice]

Because it's here, Right?

[Neil deGrasse Tyson]

It's Right.

[Chuck Nice]

It's around us. It's everywhere. Like, you're talking about stuff that is. I mean, how do you get to it?

[Brian Greene]

Right.

[Neil deGrasse Tyson]

We've had problems, unsolved problems that have lasted much longer than these 40 years in the history of science.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

So it took a long time to understand heat and energy.

[Chuck Nice]

That's very funny what you just said. It took us a very long time to understand heat. No, we didn't know what it was,

[Brian Greene]

the fundamental basis of it.

[Chuck Nice]

That's hilarious.

[Neil deGrasse Tyson]

No, no, we didn't know. Is. Is it some fluid?

[Brian Greene]

Fluid. Caloric, they called it.

[Chuck Nice]

Caloric.

[Brian Greene]

That could flow.

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

And, you know.

[Neil deGrasse Tyson]

Do you know where we did most of.

[Chuck Nice]

Well, no, that's the air. Looking like the air is a fluid. The air is a fluid, though. That's not the heat.

[Neil deGrasse Tyson]

But go ahead. One of the main centers of experiments for this.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

Were cannons. Because you fire cannons, the. The. The metal gets hot.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

So as it got hotter, they weigh it to see if it had more heat, if the heat wasn't thin.

[Chuck Nice]

Right. If it was. If it was. Was like possessing him.

[Neil deGrasse Tyson]

Possessing him.

[Chuck Nice]

Possessing him.

[Neil deGrasse Tyson]

Exactly. So, yeah. So we went decades and decades with other. So maybe I shouldn't be so hard on string theory.

[Brian Greene]

Yeah. This is a pretty good place to have gotten. Let's wrap it up right here, folks.

[Chuck Nice]

Thank you.

[Neil deGrasse Tyson]

Good night. Okay. And one last thing. I want to hear it again. Just because it was so beautiful.

[Chuck Nice]

All right.

[Neil deGrasse Tyson]

So beautiful. Just tell me. Speak to me, Bryant. Cause it's. Its sweetness to my ears when I heard you say. I think it was you, that the virtual particles in the vacuum of space coming in and out of existence, as predicted by quantum physics, they are quantum entangled with each other. And that quantum entanglement are wormholes. And those wormholes represent the literal fabric that stitches together the universe itself.

[Brian Greene]

Yeah, we were definitely talking about this at some point.

[Neil deGrasse Tyson]

Where are we on that?

[Brian Greene]

Well, it's a beautiful idea. It really comes from Lenny Susskind and Juan Maldacena and a whole army of string theorists who developed these ideas.

[Neil deGrasse Tyson]

He came here, gave a talk, one of our evening talks at the planetarium. Yeah.

[Brian Greene]

He's a wonderful book.

[Neil deGrasse Tyson]

Very innovative guy.

[Brian Greene]

Yeah. I mean, he's driven in physics for decades. So he and Juan Maldacena realized that these quantum entangled particles, which Einstein really, in A sense predicted in his EPR paper, Einstein, Podolsky and Rosen in 1935 may be connected to another Einsteinian idea which he came up with. The two months distinct from that first paper and Einstein Rosen paper on wormholes. That is two particles that are far apart can have a subtle quantum link. And that quantum link may be nothing but a wormhole yielding a shortcut through the fabric of space. That in some sense makes them very close to each other.

[Neil deGrasse Tyson]

And those wormholes themselves are what spacetime is comprised of?

[Brian Greene]

Yes.

[Chuck Nice]

So the substrate of space itself would be wormholes.

[Brian Greene]

Yes, that's right. So Mark von Ramsdott, British Columbia Canadian physicist, realized that these wormholes may be the fiber stitching together the fabric of space itself. Because he could show mathematically, if you cut the quantum entanglement, the fabric of space pulverizes, it falls apart because you no longer have the wormholes connecting pieces of space together.

[Chuck Nice]

That is wild.

[Neil deGrasse Tyson]

Okay, so I'm gonna keep watching that space.

[Chuck Nice]

Great. T Mobile 5G Home Internet has some big news you should know about. They now have the fastest 5G home Internet according to the experts at Ookla Speed Test. Alright, so let's unpack that. It means photo backups happen faster. Streaming a documentary does install halfway through. What's really notable is that the jump in speed doesn't come with added complexity. Setup is simple. Plug it in and you're online in less than 15 minutes. And the value side of the equation holds too. With a plan price that's backed by a five year price guarantee. So if you want the fastest 5G home Internet with a simple setup and savings that stick, get t mobile 5G home Internet. And if you don't want that. Wait a minute, why wouldn't you want that?

[Neil deGrasse Tyson]

That?

[Chuck Nice]

Just visit t-mobile.com homeinternet to check availability today. Price guarantee exclusions like taxes and fees apply. Fastest based on Ookla Speed test intelligence data second half 2025 all rights reserved.

[Sponsor/Announcer]

Dell PCs with Intel Insight are built for the moments you plan and the ones you don't. There for those all night study sessions. The moment you're working from a cafe and realize every outlet's taken. The times you're deep in your flow and can't be interrupted by an auto update. That's why Dell builds tech that adapts to you. Built with long lasting batteries so you're not scrambling for an outlet. And built in intelligence that makes updates around your schedule, not in the middle of it. Find technology built for the way you [e-mail] DellPCS built for you.

[Brian Greene]

And Doug. There's nowhere I wouldn't go to help someone customize and save on car insurance with Liberty Mutual. Even if it means sitting front row

[Chuck Nice]

at a comedy show.

[Brian Greene]

Hey everyone, check out this guy and his bird. What is this your first date? Oh no. We help people customize and save on car insurance with Liberty Mutual together. We're married. Me to a human, him to a bird. Yeah, the bird looks out of your league anyways. Only pay for what you need@liberty mutual.com. liberty. Liberty. Liberty. Liberty.

[Neil deGrasse Tyson]

It's time for Cosmic Queries. We should have some jingle or something. That's that. Or some animation.

[Chuck Nice]

Some animation would be good.

[Neil deGrasse Tyson]

You know, Cosmic queries. Right. Questions asked by you. If you're a patron Patreon member. Knowing that our guest today is Brian Green, the one and only. So we have a starter question.

[Chuck Nice]

Yes.

[Neil deGrasse Tyson]

From one of our own producers.

[Chuck Nice]

Yeah. Tamson, our producer.

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

Our taskmaster. Yeah. Tamsin wants to know this, Brian. If space time had consciousness and could have a favorite movie, what do you think that movie would be?

[Brian Greene]

I think it would be Planet of the Apes. Really? Oh, that scene at the end, you know, with a half submerged or sunken statue. That's it.

[Neil deGrasse Tyson]

Wow. Yeah, because that played Lucy Goosey with spacetime. Yeah. To go into the future, it's another Earth and it a different evolutionary path.

[Brian Greene]

It was the first time that time travel really meant something to me as a kid. I was like, oh man, this is crazy.

[Chuck Nice]

You know?

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

That's a good one, man.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Planet of the. The original.

[Brian Greene]

The original. Forget about the other 75,000 follow ups.

[Chuck Nice]

Exactly.

[Neil deGrasse Tyson]

Returns. Anybody Escape from the Bride of the Planet of the Apes.

[Chuck Nice]

Finality of the Planet of the Apes.

[Neil deGrasse Tyson]

You know, when I went back and saw that film, it's actually quite deep because the different species of apes had

[Chuck Nice]

different roles

[Brian Greene]

for sure.

[Neil deGrasse Tyson]

Right. So the chimpanzees were the academic class.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

Because they're close. Why not?

[Chuck Nice]

They're our closest cousins.

[Neil deGrasse Tyson]

And the baboons were like the police. Right.

[Chuck Nice]

And the orangutans are the elders.

[Neil deGrasse Tyson]

Were the diplomats.

[Chuck Nice]

Diplomats, that's correct. Right. So the politicians.

[Neil deGrasse Tyson]

It was politicians. It was a caste system.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Yeah, that's right.

[Chuck Nice]

It's pretty wild. So our first few questions have been previous previously asked by our Patreons supporters. But you said I'm gonna have to see what Brian says about.

[Neil deGrasse Tyson]

Oh, right. So they were elevated.

[Chuck Nice]

So they were elevated.

[Neil deGrasse Tyson]

Okay. It was above my pay grade right there.

[Chuck Nice]

Okay. They wrote in with a question and you were like, let Me get my supervisor.

[Neil deGrasse Tyson]

Okay. I went to a go.

[Chuck Nice]

So this is Brianberg. He says, hey, Dr. Tyson. Lord. Nice, Chuck. You should be able to nail this one. It's Brian from Portugal. Brian, shut up. He says, can you help explain the information paradox with black holes? My understanding is that quantum mechanics and Hawking radiation are at odds about this. One says information is forever. The other says information disappears when a black hole evaporates. Are we any closer to understanding how this can be? Thanks. And please keep doing what you're doing. We need real science to carry on. Live long and prosper.

[Neil deGrasse Tyson]

Ooh, nice. Now, let me preface that a little more here. Sure. Please. So I was delighted to learn that the evaporation of black holes, the Hawking radiation, is the exact inventory of fundamental particles that went in, even though it's being conjured out of the gravitational field of the black hole itself, the energy density of the field. So I said, oh, so that's a total reckoning of ingredients. But if I went in as a DNA molecule and I come out as the various fundamental particles, the information that I was DNA is gone. So, no, there's no preservation of information there.

[Brian Greene]

And that's what Stephen Hawking said. So when Stephen Hawking did his initial calculations in the 1970s, he came up with this idea that black holes could actually radiate through quantum processes, the production of particles just outside the edge of a black hole. One falls in and the other races away. And the question was, do the particles race away, have the information content about everything that fell in, or don't they? He said, they don't. My calculations show it's a thermal bath of particles, a vanilla, featureless bath of particles. No information inside of it. We particle physicists said, come on. Quantum mechanics doesn't allow information to be lost or destroyed. So if you're saying that, you're saying quantum mechanics is wrong, okay? And we're not willing to go there.

[Neil deGrasse Tyson]

Yeah, quantum is the. So it's so successful, right? That's. You gotta be ready for, okay?

[Chuck Nice]

You gotta be somebody more than Stephen Hawking.

[Brian Greene]

And this led Lenny Susskind again and Gerarda Tuft, who won the Nobel Prize, and various other people to spend 25 years trying to answer this question. And we believe, largely from string theory, that we do understand that the information does, in a very subtle way, come out of the black hole. Subtle quantum correlations between the particles that emerge from the black hole do carry all the information of, say, the DNA molecule that fell in. So you can recover all the information. We believe now There are still mysteries that we're still figuring out. But just about everybody, including Hawking before he passed away, agrees that we believe the information does come out.

[Neil deGrasse Tyson]

Preservation he had with somebody, wasn't it? Was it with Prescott?

[Brian Greene]

John Prescoll?

[Neil deGrasse Tyson]

Yeah, he was a. A postdoc when I was a graduate student at the University of Texas. Okay, yeah, yeah. So Prescoll won the bet then.

[Brian Greene]

So, so Presco won the bet. But Kip Thorne was also part of this. And Kip Thorne was unwilling to concede.

[Neil deGrasse Tyson]

He is on in our archives. Check him out.

[Brian Greene]

Yeah, absolutely.

[Neil deGrasse Tyson]

We interviewed him in his office in Pasadena.

[Brian Greene]

So. So Hawking conceded the bet that John Prescoll said the. And he gave him an encyclopedia of baseball. A lot of information. He provided him as.

[Neil deGrasse Tyson]

As the way has too much information. Now you have an encyclopedia.

[Brian Greene]

That's right. It made good on his bet. I don't know where Kip Thorne stands on this. I don't know that he has conceded.

[Neil deGrasse Tyson]

Okay, okay.

[Chuck Nice]

What's the business about the information being stored in the event horizon? Have you.

[Brian Greene]

Yes.

[Neil deGrasse Tyson]

Oh, that's. What do you call that? That's the. The holographic.

[Brian Greene]

Holographic idea. And that's part of the solution for why we believe the information comes out. Again, that's. This guy is incredible. Things fall into a black hole and we believe that they leave on the surface in some sense a copy, a residue of their information. And that's how it can come back out. It never actually goes away.

[Chuck Nice]

It never went in. The imprint was left on the event horizon. Yes, Very cool, man. Super cool, man.

[Neil deGrasse Tyson]

Yes. So we have an explainer on whether or not we're living in a black hole. Properties. Yeah, right.

[Brian Greene]

And if it's big enough.

[Neil deGrasse Tyson]

Yeah, yeah, yeah. Okay.

[Chuck Nice]

All right, here we go. This is Rachel.

[Neil deGrasse Tyson]

Rachel says we're still in questions that I. I had to call my boss.

[Chuck Nice]

Rachel says, what's up, Dr. T? Rachel here from Austin, Texas. I've been thinking about the spinning universe hypothesis which suggests our cosmos might be rotating as a whole. This idea has been proposed as a potential way to resolve the hubble tension. But it got me wondering. If the universe is indeed spinning, could the force we attribute to dark energy, which is causing the accelerated expansion, actually be explained by a kind of cosmic centrifugal force? So she's saying that we. We just on a whirly bird. We're in the whirling dervish. We're in a teacup ride.

[Brian Greene]

It's hard to see how you'd make that work. When we see the evidence for dark energy, it seems to be so called isotropic. It's the same in every direct in which you look. Whereas if the universe is spinning, there's an axis, there's an angular momentum that picks out some directions as different from others. That's right. So it's hard to see. So if you look up along the

[Neil deGrasse Tyson]

axis, there's no centrifugal force.

[Brian Greene]

Yes. But if you look off the axis, we study the motion of distant galaxies. We look across the entire galaxy, every direction. And so we have sufficient data, I think, to rule that possibility out. But who knows? Write a paper and we'll see whether it works out.

[Chuck Nice]

Yeah, that was all right. What a great question. Question these. Okay, we're gonna move into regular questions now.

[Neil deGrasse Tyson]

Wait, wait. Why don't we pull out one that was there and I forgot who asked it. And it was about whether we'd have a quark catastrophe. So we had a Patreon member write in. The questioner knew that if you have two quarks.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

In some kind of nucleon, then you try to pull them apart. There's a point where that snaps, but you've invested so much energy in it, the two new quarks show up in that instant. Now you have two pairs of corks. Right. We good with that? Yeah. Okay, so in a black hole, or maybe in the Big Rip, either. Let's look. Let's look at the. You're descending to the. To the singularity. The. The two quark particle falls. Tidal forces get greater and greater, and then it splits the two quarks. So now we come two pairs of quarks as they fall in. Then it becomes four pairs and then eight pairs. And it'll just be this unlimited increase in the number of quarks as it descends to the singularity. Why doesn't that happen?

[Brian Greene]

Well, you do feel tidal forces as you get ever closer to the center, for sure.

[Neil deGrasse Tyson]

But I'm not a quark.

[Brian Greene]

And it's a finite time scale between when you cross the event horizon and you hit the singularity. And I can well imagine that particle pairs are created in the last moments of this. But whether all of the energy gets transformed in this way, that seems unlikely. You'd have to calculate it.

[Neil deGrasse Tyson]

After I rethought about it, it occurred to me it's pulling that energy out of the black hole so it would evaporate the whole. Oh.

[Brian Greene]

If they're thinking that an infinite energy transfer, then, yeah, absolutely. Everything is finite. Time scales, finite energies. And so, yeah, exotic processes can certainly happen when the gravitational force is that powerful.

[Neil deGrasse Tyson]

Right.

[Brian Greene]

Now, of course, when you get to the singularity, we have no idea what actually happened.

[Neil deGrasse Tyson]

Theorists haven't figured it out yet.

[Brian Greene]

We have not. That's what. Okay, but that's actually a real point. That's one of the goals that we've not yet achieved.

[Neil deGrasse Tyson]

And the Big Rip would be the same thing. There's a point where the.

[Brian Greene]

Yeah, that's true too. Yeah. If it was sufficiently high, would get

[Neil deGrasse Tyson]

on the scale of nucleons and split apart the quarkantic war pairs and then make another pair and just keep doing it.

[Brian Greene]

Yep. I mean, there are many other processes that can happen in the world, so I wouldn't just focus on this. There are all sorts of ways that energy can transfer from the Big Rip, or the gravitational energy of a black hole into particle production, into various kind of processes.

[Neil deGrasse Tyson]

Creates a whole universe of quarks.

[Brian Greene]

You'd have to sort of calculate the rate at which those processes happen versus other things.

[Neil deGrasse Tyson]

The entire dark energy universe inside you.

[Brian Greene]

But we're still inside the black hole.

[Neil deGrasse Tyson]

No, no. Now we're just looking at the big red.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

I'm just wondering if this keeps happening. Yeah, it's using up the energy of.

[Brian Greene]

But then, of course, if that were the case, it would no longer undergo the accelerated expansion.

[Chuck Nice]

Exactly.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

Okay. All right. This is Michael De La. De La Morena who says, is time a dimension or a field? It seems more like a field because it can be affected by gravity.

[Neil deGrasse Tyson]

That was another one that I punted to Brian.

[Chuck Nice]

Is time a dimension or a field?

[Brian Greene]

Well, I'd say the deep lesson of Einstein was that space and time can be affected by their environment, and they in turn, create the very environment that then back reacts on their own shape and structure. And so we usually think about time as a coordinate, a label telling us when things happen, Just like coordinates in space tell us where things happen. And the unexpected thing is that label, the amount of time between two different locations can be influenced by the force of gravity.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

But that doesn't require that it be a field.

[Brian Greene]

Yes. It doesn't require it be a field

[Neil deGrasse Tyson]

to be influenced by a force.

[Brian Greene]

But I understand the intuition because we used to think that. That the labels, the locations of where and when things happen, In a Newtonian perspective, they're just inert. They just sit there. They don't do anything. Einstein elevated them to be dynamical qualities of the world. And that's the deep lesson.

[Chuck Nice]

Very cool.

[Neil deGrasse Tyson]

All right.

[Chuck Nice]

Great question, Michael. All right, this is Cody Rosenberg who says, hello, doctors and Chuck. I'm Cody Rosenberg from Eugene, Oregon. Please note. Know that y' all are goaded for us armchair astrophysics physicists or physics enthusiasts. All right, very nice. Anyway, do you guys think that life is inevitable? Do you think it would be weird for a universe to exist that can't be experienced or observed? Do you think we are the physical manifestations of the universe yearning to experience itself?

[Brian Greene]

So it's a very John Wheeler like way of looking at the world. Wheeler loved to say that we are the way that the universe. Universe becomes cognizant of itself.

[Neil deGrasse Tyson]

It's a poetic picture.

[Brian Greene]

You had a U with an eyeball.

[Neil deGrasse Tyson]

Yeah, yeah, A U, a serif, you. And on one of the. Upwards of the U, there's an eyeball looking at the other line of the U. So the universe looking at it.

[Brian Greene]

So it's a, you know, narcissistic or beautiful, depending on your perspective that we're here. So the universe can think about itself.

[Chuck Nice]

Yeah.

[Brian Greene]

I don't know of any law that makes life inevitable. It seems it was a lot of happenstance between the Big Bang and today. But, you know, we don't understand a lot about the world. And maybe one day we'll find there's this law, this inevitability of the existence of galaxies and stars and planets and people, at least on one such planet. I don't know of any such law today.

[Chuck Nice]

So let me ask you both this.

[Neil deGrasse Tyson]

But there's some thinking that. And this is wishful thinking, not because someone has researched this.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

That you go to a different planet, you can take a geologist there, they'll be comfortable there because they'll know what a rock. You know, there's an incident.

[Chuck Nice]

Because they see their crap everywhere.

[Neil deGrasse Tyson]

Yeah, that's right. So the rocks and the minerals. There might be some more exotic ones. Exactly. But they have a sense of how. What elements do when they're heated for a certain amount of time under pressure.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And that repeats depending on the planet. So we can. So there are general law rules of geology that apply to all planets. So let's go to biology.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

Could the DNA molecule be a natural consequence of complex chemistry operating on planetary surfaces? Could it be as natural on a planet as rock chalks are to the geologist?

[Chuck Nice]

And that. That's what I was about to ask. And both of you can chime in on this. How cheap is life? So forget if it's inevitable. How cheap is life?

[Neil deGrasse Tyson]

I don't know what that means.

[Brian Greene]

Well, in the sense that it formed relatively quickly on the planet Earth. So it didn't take an enormous amount.

[Neil deGrasse Tyson]

If it took billions of years, you'd say, whoa, that was some hard stuff. Yeah, yeah. It formed, it just. In fact, we used to. How long do you think it took?

[Brian Greene]

Half a billion, I'd say.

[Neil deGrasse Tyson]

Okay. That's what we used to say. Ah, okay.

[Brian Greene]

What would you say now?

[Neil deGrasse Tyson]

Okay, we used to say that because you'd start the clock at when Earth formed. Right, right. Four and a half billion years. Yeah, yeah. And then the early signs of Life are like 3.8, 3.9. So you say it's 600 million years, we used to say. And then we said, no, no, that's unfair. That's unfair. When Earth formed, there was periods of heavy bombardment where the surface of the Earth could not have sustained complex chemistry, of course, because the energy's too high, it breaks apart all. You let the Earth cool, for goodness sake. So the cooling let it cool at about 4 billion years. That's half a billion years. At 4 billion years now you start to clock rock and you have life 200 million years later.

[Chuck Nice]

Wow, that's really great.

[Neil deGrasse Tyson]

Yeah, right.

[Chuck Nice]

In the grand scheme.

[Neil deGrasse Tyson]

In the grand scheme, yeah.

[Chuck Nice]

So that's what I'm saying. So life is pretty cheap then.

[Neil deGrasse Tyson]

Yeah, it's 5% of the total time Earth has been around.

[Brian Greene]

So again, however, I, I think that's likely the way to talk about it. But there are so many detailed physical chemical processes that maybe they just so happen to come together in this one planet of the trillion that are out there. So when we understand it better, that cheapness, we may explain it by a coincidence of a whole lot of factors that just happen to align Right. On our planet. I don't think that's how it's going to turn out. But it's a possibility.

[Chuck Nice]

It's a possibility, yeah.

[Neil deGrasse Tyson]

Well, except that, you know, there are amino acids on, on meteorites.

[Chuck Nice]

Yeah, we found them already.

[Neil deGrasse Tyson]

Right, yeah.

[Brian Greene]

An interesting question though is the way that proteins are coded by amino acids is uniform across all life. Life. It's the same code. Three base pairs on the genetic code give rise to a particular amino acid. That is the code that works for you, me, and all life on another planet. If there is other form of life, the deep question will be is it the same code?

[Neil deGrasse Tyson]

Right.

[Brian Greene]

Or is it different?

[Neil deGrasse Tyson]

So doesn't need DNA at all?

[Brian Greene]

Right, right. And so if it's different, that would be wonderful. That would suggest that life in a whole variety of different forms, forms can exist throughout the universe.

[Neil deGrasse Tyson]

Fully explored all the ways of Being alive.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

Wow. All right, well, great question. Way to go, Cody. All right, this is Aaron Bailey who says. Hey, Star Talk. I am Aaron from Florida. And. And we're sorry.

[Neil deGrasse Tyson]

Florida's trying. All right.

[Brian Greene]

Yeah.

[Chuck Nice]

So Aaron says, long time viewer, first time subscriber. Thank you. I appreciate that. According to Einstein, Einstein's equations, is time travel still possible if you are traveling to a black hole? And why can't we use gravitational detectors to measure the properties of dark matter?

[Brian Greene]

So in the first question. Yeah, I mean, Einstein, special and general relativity both embrace a certain kind of time travel, and the black hole provides the mechanism for one kind. If you go hang out near a black hole. Hole.

[Chuck Nice]

Right.

[Brian Greene]

Time for you elapses more slowly compared to someone who's far away.

[Neil deGrasse Tyson]

Famously portrayed in interstellar.

[Brian Greene]

And so if you go to the edge of a black hole and you hang out and then you come back, everyone that you meet is going to be much older. Their clock was going much faster than your clock. And that is. Some people say, well, that's not time travel. That is time travel. You've traveled into their future, which would have been your future if you stay there. Exactly.

[Neil deGrasse Tyson]

You know who they left up in the. In the ship?

[Chuck Nice]

The black dude. He came back like, oh, God damn.

[Brian Greene]

23 years. 6.

[Chuck Nice]

You know, I serious now. You know, I'm on Social Security.

[Brian Greene]

I don't get it.

[Chuck Nice]

You go down there, you tell me, you come right back. You worse than my kid. You wor. You're worse than my kids. I don't get it. Meth, math. Matthew McConaughey, he.

[Neil deGrasse Tyson]

All right, what was the second half to that question?

[Brian Greene]

What was the other half?

[Chuck Nice]

And so the second half, he says, why can't we use gravitational detectors to measure the properties of dark matter?

[Brian Greene]

Well, we do. The way we know dark matter exists is by the gravitational influence that it has on its environment. What we're unable to do is identify what the dark matter is made out of. And so we have these detectors all over the planet trying to capture little particles of dark matter, if that's the right explanation. We haven't been able to find any yet.

[Neil deGrasse Tyson]

You want to do now what? Okay. You know, they're pulsars. They're rapidly rotating neutron stars. They get very precise, extremely precise.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And they're across the galaxy. They're not all that many of them, but there's enough to map out the galaxy. So if you precisely know and measure the pulses of these pulsars. Okay. You can track a gravitational wave moving across the galaxy.

[Chuck Nice]

Yes. You're kind of using them like buoys in the ocean.

[Neil deGrasse Tyson]

Ooh, good analogy. Beautiful idea. And you don't even need LIGO for that. You just need height sensitive, high precision time.

[Chuck Nice]

Yeah.

[Brian Greene]

For gravitational waves of a certain wavelength. This is a beautiful way of detecting their influence.

[Chuck Nice]

Super cool, man.

[Neil deGrasse Tyson]

Yeah.

[Chuck Nice]

All right, let's move on to Alex Frias, who says, hey, Dr. Tyson. Lord. Nice. Alex here from Mexico. Oh, I should say Alex.

[Neil deGrasse Tyson]

No.

[Chuck Nice]

Alexander Alexandro from Mexico.

[Neil deGrasse Tyson]

Isn't that racist that you assume I can be racist?

[Chuck Nice]

I'm black. I don't know if you realize. Okay. The world invented racism for me. Okay, okay, here we go.

[Neil deGrasse Tyson]

He says, did I tell you? Did I tell you this? I was giving a public talk, and I thought I'd say something funny. I was talking about the dinosaurs, and they went extinct by an asteroid that hit the Yucatan Peninsula. Yucatan Peninsula of Mexico. And I said, but that's not what the dinosaurs called it. Okay, okay. I thought it being funny. I thought it'd be funny, right? I think it'd be funny. And then someone in the front row said, they called it Mexico.

[Chuck Nice]

That's funny too. Spanish fluid dinosaur. Spanish fluid dinosaurs. Yeah. Okay.

[Neil deGrasse Tyson]

All right.

[Chuck Nice]

And then you had Trumpasaurus who was just like, keep him out. Anyway, I've always been intrigued and confused by the idea of. Of super symmetry.

[Neil deGrasse Tyson]

Oh, nice.

[Chuck Nice]

If the Standard Model of particle physics is one of the most successful theories we have, what is telling us that it needs doubling up? What would supersymmetry fix in our understanding of the universe? And what problems might it create? Thank you both, and greetings from your neighbors in the beautiful Upper west side.

[Neil deGrasse Tyson]

Oh, nice.

[Chuck Nice]

Oh, look at that. Way to go, Alex.

[Neil deGrasse Tyson]

Right up the street of Manhattan.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

So let me sharpen that even further.

[Brian Greene]

Sure.

[Neil deGrasse Tyson]

So the Standard Model is quite an organizational map of our particles and our forces and the like in its current state. Now that we've got the Higgs. The Higgs. Is it missing anything? Is it a closed box right now? And if we do anything to it, does it simply make it more powerful? Or do we know we need things to explain other things that we don't yet understand?

[Brian Greene]

Good, good, good. So the main motivation for supersymmetry is to address exactly the way you frame the question, which is when we study this Higgs particle, this newest addition that we found on July 4, 2012, at least that's where the announcement was. When you look at the mathematics, it says that the mass of the Higgs particle should be much, much bigger than the mass that we find and when we try to keep the mass at the value measured, we have to stand on our mathematical heads to do so. We have to tune and tune and tune. If supersymmetry were true, the terms that would push the Higgs mass up, they cancel out from those pairings. That's why we need the pairings. That's why we need the doubling. And if you can cancel out the new contributions, you can rest easy. The Higgs mass will stay at a small value.

[Chuck Nice]

Look at that.

[Neil deGrasse Tyson]

So how many more particles come along?

[Brian Greene]

It doubles. Doubles it. It really does. For every known particle, there is a partner. Electrons have.

[Neil deGrasse Tyson]

Super symmetric.

[Brian Greene]

Yeah, super symmetric. Yeah. So the electron has the selectron. Quarks, squarks, neutrinos. Snutrinos. No.

[Neil deGrasse Tyson]

No.

[Brian Greene]

Yes.

[Neil deGrasse Tyson]

No.

[Brian Greene]

Yes. I don't name them.

[Neil deGrasse Tyson]

Neutrino. No.

[Chuck Nice]

Yeah. You know why? Because somebody. When they found that they're like neutrinos. Neutrinos.

[Brian Greene]

And so the big hope, if you would have spoken to me when I was a graduate student in the 1980s. The Big Hope, and the reason we believe that string theory might be five years away was we expected super symmetry, which is the super. In super string theory, we thought it would be found. Those particles would be found at the Large Hadron Collider, and they were not found.

[Chuck Nice]

Wow.

[Brian Greene]

And so this will never be found. Well, that's probably true. Because the collider has a limited energy reach. Nothing in our theories tells us how massive the partner particles would be. If they're sufficiently massive, they'll be beyond the reach of the Large Hadron Collider. So there's a natural explanation for why we didn't find the particles, but we were certain that we would.

[Neil deGrasse Tyson]

He wants another collider.

[Chuck Nice]

Yeah. There you go.

[Neil deGrasse Tyson]

You're gonna need one.

[Chuck Nice]

Look at that. Well, that is fascinating, though.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

And does the Higgs have the. Do we have a name for the other particles? Cool.

[Brian Greene]

Higino.

[Chuck Nice]

Higino.

[Neil deGrasse Tyson]

Yeah, I prefer squigs.

[Chuck Nice]

You're gonna go with squs. Go with squigs.

[Neil deGrasse Tyson]

The photon. What's the phot?

[Brian Greene]

Fotino.

[Chuck Nice]

Really? Really.

[Neil deGrasse Tyson]

Okay.

[Brian Greene]

And the W and Z bosons. Those are harder xenos or os.

[Neil deGrasse Tyson]

Weos.

[Brian Greene]

They get a little bit.

[Chuck Nice]

Yeah, yeah, that's getting a little funny.

[Neil deGrasse Tyson]

And how about the graviton? On.

[Brian Greene]

Well, you see, the super symmetry that we're talking about doesn't have gravity in it when you're just talking about the Standard model.

[Neil deGrasse Tyson]

Oh, Standard Model doesn't have gravity.

[Brian Greene]

Yeah, but if you include gravity.

[Chuck Nice]

Right.

[Brian Greene]

Then there is a Version, it's called super gravity, and it comes out of string theory as well. And it's the gravitino.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

All right.

[Chuck Nice]

From the graviton.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Right. Okay.

[Chuck Nice]

Okay. All right. All right. Well, way to go there, Alex.

[Neil deGrasse Tyson]

We're still looking for him.

[Chuck Nice]

Yeah.

[Brian Greene]

You're still looking for him. There's no evidence.

[Chuck Nice]

Is this just a matter of a lack of detectors? Could you build enough detectors where we could get all this, capture all this stuff?

[Brian Greene]

Not so much detectors. It's a matter of the energy. So how big the detector, how big the collider is. And that's, you know, colliders are expensive, and the bigger they are, the more money they cost.

[Neil deGrasse Tyson]

And we had a big one going in our, you know, in our side of the pond. The superconducting super collider in Texas, funded in the 1980s under Reagan.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And dug the hole, got all ready. Waxahachie, Texas, it would be three times as powerful, I think.

[Brian Greene]

Yeah. About 50 TEV. And we have 14 TEV.

[Chuck Nice]

Yeah, yeah.

[Neil deGrasse Tyson]

So three times the power of the one that was built in Switzerland. And then early 90s, they zeroed the budget and they said, oh, those cost overruns and this sort of thing.

[Brian Greene]

But, oh, some kind of defense thing. We no longer were fighting for our lives.

[Neil deGrasse Tyson]

Broke out in Europe.

[Chuck Nice]

The fall of Bell. Yes, yes.

[Neil deGrasse Tyson]

Peace breaks out. And all of a sudden it's like, we don't need physicists.

[Chuck Nice]

We need this.

[Neil deGrasse Tyson]

What do we need physicists for? And their little toys. You never heard of cost overruns in any other particle accelerator for the whole 20th century?

[Chuck Nice]

Right. Interesting. This is Blake who says. Hey, it's Blake. Greetings from warm, sunny Columbia, South Carolina. Way to. Way to rub it in there, Blake. He says there are quite a few theoretical particles that have been discussed on this show. The graviton, the tachyon strings, etc, but we don't seem close to actually finding any of them. Are there any experiments proposed that might help us capture and learn about these elusive particles? If they exist? And slightly more an engineering question. If we did, did find them, how might we use them for the benefit of humanity? Yeah, do they have a use if we find them? I mean?

[Brian Greene]

Well, if dark matter is actually found and it is a particle, look, it'll deepen our confidence, our understanding. Can I imagine applying dark matter particles to build something? The whole point is they're incredibly elusive. They only interact gravitationally.

[Chuck Nice]

How do we even capture them if they don't interact with anything?

[Neil deGrasse Tyson]

Well, they do interact with themselves.

[Chuck Nice]

They interact with themselves.

[Brian Greene]

Yes, but Anything that has energy interacts gravitationally and. And these dark matter particles through indirect quantum processes do interact with ordinary matter.

[Chuck Nice]

And that's how these detectors universe is accelerating. Or is that the.

[Brian Greene]

Yeah, well, yes, you can. Well, that's the dark energy. Yeah, but it's the same basic idea. And so, yes, you can detect these things, but that's different from. From gathering them together and engineering with them. So I don't. I don't see any direct benefit, you know, but again, it's the same argument we made before. The deeper your understanding. That's step one. Someone figures out where that goes someplace else.

[Chuck Nice]

Right. Okay, gotcha. All right, this is Luke Senior who says, best regards from joliet. He says Dr. Luca Laporta, Ph.D. translation scholar and sinologist. He says, could it be the entanglement phenomenon is simply a matter of absence of the time dimension at the scale of the particles, and that we see two particles interacting instantaneously at a distance in some, you know, his word, magical way in their own three dimensions only universe. They're just unaware that a change of state has occurred. That for them there's no before entanglement, after entanglement. Thank you very much. It's a very well thought out question. Does it make sense?

[Brian Greene]

It does. And I think we can interpret it more or less along this wormhole idea that we were describing before. The wormhole notion. Again, again, this is still very much at the forefront. We're still working out the details. But if it is the case that two distant particles are connected by a wormhole, if they're entangled quantum mechanically, then it would be as if they're right next to each other.

[Chuck Nice]

To them, they don't know the difference

[Brian Greene]

to them, they don't know that they're far apart. And so that's a variation on the same thing. I don't think you can say they live in a world without time. Because the conundrum is to us, beings that do have time, you do something here and instantaneously, according to us, affect something over there. And that would still be a puzzle. No matter what. No matter what. And one explanation would be, well, they're actually closer together than you think by looking at them because they have this secret shortcut connection which could be the wormhole.

[Neil deGrasse Tyson]

So I think for so many years, people were imagining wormholes as some kind of ride in a water park.

[Chuck Nice]

Exactly.

[Neil deGrasse Tyson]

You know, even in the movie Contact, Jodie Foster is going through. And so. But no, you just step through.

[Chuck Nice]

No, you step through.

[Brian Greene]

I think it depends on the nature of the wormhole. But yeah, there can be versions where it's effectively stepping from one place to another.

[Chuck Nice]

Star Trek did it right, though. They had a portal where it looked

[Brian Greene]

like a doorway threshold sitting on the edge of forever.

[Chuck Nice]

On the edge of forever.

[Brian Greene]

Yeah.

[Chuck Nice]

And that's a wormhole. You step through it and you're already there. There's no ride, there's no nut. You just step through it and they're already there.

[Brian Greene]

And that's another one where they were going to save someone's life and they

[Neil deGrasse Tyson]

decided not to and they realized what

[Brian Greene]

they're going to change the future.

[Neil deGrasse Tyson]

Yes. In fact, I was. I was talking with Bill Will and he said that was his favorite episode.

[Brian Greene]

Oh, really? Yeah, it's my favorite watching as a viewer.

[Neil deGrasse Tyson]

Yeah. Because it was. It dealt with time travel in a very emotional way. Emotional and unorthodox way. Yeah.

[Chuck Nice]

And causality is. Is actually addressed. All right. Zachary e. Says hello. Dr. Tyson. Lord. Nice. Dr. Green, is it possible that through the many worlds interpretation, quantum immortality can become macroscopic? If every single possible state of every single particle in existence is equally real. I feel like the superposition of a single particle in quantum immortality theory can be expanded to incorporate the superposition of every single particle in existence.

[Brian Greene]

Yeah. And look, you know, another way of saying it is we said before that the many worlds allows a world in which anything compatible with physics is realized. Us living to 100, 200, 500, a thousand. I don't know that there's a law of physics that prevents that can happen Now.

[Chuck Nice]

There is a law of. Jesus, I'm bored. That won't allow that the boredom. Can you imagine living a thousand years? Oh, kill me just thinking about it. I want to die.

[Neil deGrasse Tyson]

So wait, here's something that we did not raise, which was if there's another identical.

[Chuck Nice]

Me.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Is it me?

[Brian Greene]

That's the deep question. That is the question.

[Chuck Nice]

Consciousness question.

[Brian Greene]

And I think the answer to that is yes, because I think the answer is no.

[Chuck Nice]

Why?

[Neil deGrasse Tyson]

Because we've already kind of done that experiment. They're called twins.

[Brian Greene]

No, I'm saying that person has literally your memories, literally your self of sense of self. Until something measurement that causes you to

[Chuck Nice]

be different from that.

[Brian Greene]

Yeah.

[Chuck Nice]

Yeah.

[Brian Greene]

So it's truly you.

[Chuck Nice]

That's wild.

[Brian Greene]

I mean, if. If I spoke to that version of you, you would adamantly claim, yes, I'm the same guy.

[Chuck Nice]

That's me.

[Brian Greene]

It's me.

[Chuck Nice]

It's me. Damn it. That's funny.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

I don't know what to say.

[Brian Greene]

I've never heard you Say that.

[Neil deGrasse Tyson]

So that means we are living forever. Their reincarnation.

[Brian Greene]

Yeah, yeah.

[Neil deGrasse Tyson]

Are all over this.

[Brian Greene]

That's right.

[Neil deGrasse Tyson]

Right.

[Chuck Nice]

Wow.

[Brian Greene]

Or at least extraordinarily long. You know, maybe there is some physical law about maybe the proton decays.

[Neil deGrasse Tyson]

Right, right.

[Brian Greene]

10 to the 38 years, you know.

[Neil deGrasse Tyson]

38.

[Brian Greene]

Yeah, whatever. You know, more than 10 to the.

[Neil deGrasse Tyson]

32. Yeah, 32.

[Chuck Nice]

Wow. All right. This is Marcus Ruzan, and Marcus Razan says hello. Neil and Brian. Love the show. I've been wondering something about time and light. If nothing can travel faster than light and the speed of light is a universal constant, could it be that time itself is actually an emergent property of light? Is it possible that what we perceive as time is actually just a consequence of us traveling through space time at a finite speed below the speed of light? Is that not confirmed by the fact that from the point of view of a photon, there is no time? Thanks and keep looking up from Singapore. Yeah, okay.

[Brian Greene]

In some poetic sense, I agree with what the questioner asks. They're saying that if a photon had consciousness right from its perspective, it would not know. It would not know that time is elapsed. Now, I think it's really important to recognize that. That you're extrapolating Einstein's result to a particle for whom the equations don't literally apply in the way that we're using them.

[Chuck Nice]

Correct.

[Brian Greene]

So if you apply Einstein's ideas to any massive body, you find that they can't travel at the speed of light, and therefore they will always have this conception of time. But if you want to push it to the absolute limit, which I call poetry. Not quite mathematics, then. Yes.

[Chuck Nice]

Right. Because the key is the photon has no mass.

[Brian Greene]

Yes, that's the key.

[Chuck Nice]

Yes, that's it.

[Brian Greene]

Y.

[Chuck Nice]

So once you have mass, you can't be a photon, and you can't. You'll never experience what that photon experience.

[Brian Greene]

Precisely.

[Chuck Nice]

All right. Okay. Well, there you go, Marcus, but thanks for the.

[Neil deGrasse Tyson]

You know, I had nothing to add to that. Okay.

[Chuck Nice]

All right. This is Patrick Dees, and patrick says hello. Dr. Tyson, Dr. Green. Lord, nice. Pat Deets from Ravenna, Michigan. Could the reason we cannot see dark matter also account for the expansion of the universe due to dark matter moves faster than light? Let me read that again. Could the reason we cannot see dark matter also account for the expansion of the universe due to dark matter moving faster than light?

[Brian Greene]

Okay, that's a tough one to parse.

[Chuck Nice]

It's been really rough. But, yeah, I see what he's saying. How can you see the thing that's faster than the thing that allows you to see the thing.

[Brian Greene]

Right. I get this sort of collection of words, but the problem is.

[Chuck Nice]

Okay, by the way, people to satchel a word. This is why I love scientists, because they know how to call you a dumbass. Ever saying those words.

[Brian Greene]

See, the important point is that for a particle to be a particle of dark matter, it has to have mass. Once it has mass, it can't travel faster than speed of light. So the ideas don't meld together in a consistent way.

[Chuck Nice]

There you go. All right, all right. I like the question. Just for the fun of it. All right, thank you, Patrick. This is Mr. Zoot. And Mr. Zoot says. Says, Dear Star Talkers, Jeffrey here pronounced Jeffrey chuck. Screw you, Mr. Zoot. He says, I understand electron orbitals are really probability clouds, but still exist in discrete energy levels around the nucleus. What then happens during ionization? Do they stay as a probability cloud just untethered from the. Their anchor, so to speak. Do they still have discrete energy levels? Hey, what gives? And thanks.

[Brian Greene]

So if that. It's a great question. And so it certainly does stay as a probability cloud or probability wave. If an electron is ionized, say from hydrogen, but if that electron is living in a universe that is not a box that's infinitely big, then we don't believe its energy levels will be quantized.

[Neil deGrasse Tyson]

You think it'll be continuous?

[Brian Greene]

Yes. So if you have a particle in a box. If you have a particle in a box, then the energy levels are quantized, but they are dependent upon the size of the box.

[Neil deGrasse Tyson]

Because you're solving the wave equation, you're

[Brian Greene]

saving the wave equation, you're expanding the.

[Neil deGrasse Tyson]

What's it called?

[Brian Greene]

The harmonics.

[Neil deGrasse Tyson]

The harmonics of the wave.

[Brian Greene]

And the harmonics have to fit inside the box. They have to fit inside the box. But if there's no box, then they could have any wavelength at all, any energy.

[Neil deGrasse Tyson]

The energy of a free electron is not quantized.

[Brian Greene]

Correct.

[Neil deGrasse Tyson]

I did not know that.

[Chuck Nice]

That's, I've never heard that before.

[Neil deGrasse Tyson]

Explained it. It's obvious that it could only be that way.

[Chuck Nice]

That makes. That's, that's wild.

[Neil deGrasse Tyson]

Wow.

[Chuck Nice]

That's absolutely wild. Very cool, man. Wow. Great, Great question.

[Neil deGrasse Tyson]

Just to highlight because he said something important here. Yeah. So once. We'll call it a box. But let's, let's, let's look at a tube. Let's look at like a, A, a, an organ tube.

[Chuck Nice]

Okay.

[Neil deGrasse Tyson]

Okay. So like a pipe. Pipe organ.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And, and you can ask what kind of wave can you set up inside that tube, and it can only hold a wave where the complete wave is there.

[Brian Greene]

Right.

[Neil deGrasse Tyson]

You can't hold like a half wave. Right, Right. So it sets what the wavelength is, the frequency of the sound. That's the wavelength. You get that from the wavelength in each tube. So different tubes have different frequencies that resonate inside of those tubes. And so when I think of atoms, I think of you got the nucleus with the protons sets up a box. And so you. Then you do the math and you get a set of wavelengths, I'll call them that, that fit inside this box. And it's unique for every atom. And that's what gives you the spectra of each atom. That's where each atom has a unique spectrum.

[Brian Greene]

Right.

[Neil deGrasse Tyson]

Yeah. It's really cool.

[Chuck Nice]

That is excellent. Wow. I learned stuff on this show.

[Neil deGrasse Tyson]

So Great. So did I. I just never thought about free electrons in their energies.

[Chuck Nice]

Yeah.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

This is Brian Nadeau who says. Hey, Dr. Tyson, Dr. Green. Lord. Nice. Brian from upstate New York here. Would the discovery and verification of the graviton assist at all in reconciling general relativity and quantum.

[Neil deGrasse Tyson]

I love that. Isn't it just assumed that there's a graviton.

[Brian Greene]

And that assumption needs to be verified, hopefully.

[Neil deGrasse Tyson]

And what's the energy of a graviton relative to the waves that we just detected?

[Brian Greene]

Well, the energy that the mass of a graviton, we believe is zero because gravity also travels at the speed of light. So it's much like a photon in that particular way. And yes, if we could ever really detect a gravitational graviton, do experiments with gravitons, scatter gravitons off of each other, then yes, we would learn an enormous amount about general relativity and quantum mechanics.

[Neil deGrasse Tyson]

Yeah. But we'll help you merge them. Well, our quantum expression of gravity.

[Brian Greene]

That's right. In fact, the very existence of a graviton would be the first evidence that gravity is quantized. And so we are assuming that there is a graviton. But verifying it would be a huge step.

[Neil deGrasse Tyson]

Who was the first to presume that

[Brian Greene]

the idea of the graviton.

[Neil deGrasse Tyson]

I don't historically know, but Einstein was the gravitational wave.

[Brian Greene]

Yeah. Well, so when you have a wave. He was a reluctant gravitational wave person. He was really uncertain in 1916 and 1918 about whether they were real.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

Amazing.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Yeah. So I'm just saying the quantum assumption is that where you have a wave, you also have a particle.

[Brian Greene]

Yes.

[Neil deGrasse Tyson]

Yeah. And like the photon is a wave and a particle.

[Brian Greene]

Yeah.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

Wow.

[Neil deGrasse Tyson]

Okay.

[Chuck Nice]

That's super cool, man.

[Brian Greene]

That's a good question, though. Who first introduced the very idea of a graviton? I don't know the answer.

[Neil deGrasse Tyson]

It feels kind of natural if you. If you're. If you're gonna.

[Brian Greene]

I'm gonna look that one up.

[Neil deGrasse Tyson]

Quantum. Yeah, quantum quantify.

[Brian Greene]

Yeah.

[Chuck Nice]

All right. This is Tash Shaw, and tosh says. Dear Dr. Tyson, Dr. Green. Lord. Nice. I'm Tosh from Orange, Australia. I'm a longtime listener. My boyfriend bought me a subscription to Patreon for Christmas.

[Neil deGrasse Tyson]

Oh, nice.

[Chuck Nice]

Very nice. What a nice boyfriend.

[Neil deGrasse Tyson]

Very nice gift.

[Brian Greene]

Yeah.

[Chuck Nice]

That's a smart man. I have read that other dimensions could potentially be detected through gravitational and other anomalies. I was wondering how we would be able to distinguish these from any effects of dark matter. So would there be dimensional differentiation?

[Brian Greene]

Yeah. In fact, a proposal that was made a while ago is that at a collider, like the Large Hadron Collider, when you slam protons together, you can calculate and measure how much energy you have before the collision. You can measure how much energy you have after the collision. And if you have less energy after the collision, that energy must have gone somewhere. And the possibility is the energy went into the other dimensions. And so this was missing energy signature of extra dimensions that we were again hoping we would see.

[Neil deGrasse Tyson]

Why would not and not as what occurred in the first neutrino experiment.

[Brian Greene]

That's right. So it could be some other particle, mysterious particle, carrying away.

[Neil deGrasse Tyson]

Right. But there's the first neutrino. They didn't experiment.

[Brian Greene]

And there was an imbalance.

[Neil deGrasse Tyson]

Yeah, there was an imbalance. Imbalance. It was like you start with this much energy and they have less.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

And you accounted for all the particles.

[Chuck Nice]

Right.

[Neil deGrasse Tyson]

So maybe there's another particle, but what's up with that? And they say if there is a particle, it has to be neutral and it has to be very low mass. And the guy who proposed it was Italian. So little neutral, one neutrino, like bambino, little baby neutrino. What you got? Check.

[Chuck Nice]

Let's go to cosmic. Moss says hello, everyone. Love the show and every star you've had on it. You guys are great. I love the way you teach. Please keep the education up. Dr. Tyson, Dr. Green, could theoretically a frequency be matched at two points in space by a microparticle uninhibited by resistance, only to be met by its astrophysical counterpart?

[Brian Greene]

Neil, I think you should take this.

[Neil deGrasse Tyson]

I don't know that I understand. Understand the question.

[Chuck Nice]

Kind of like matter anti matter, but the particle is already in existence, and then it's a counterpart that impedes, I guess, the entanglement. It's kind of like.

[Neil deGrasse Tyson]

Read the first sentence again.

[Chuck Nice]

All right. He goes, could theoretically a frequency. All right, so that's the. I guess his version of the string be master two points in space by a micro particle. So that's the entanglement maybe uninhibited by a resistance only to be met by its astrophysical counterpart.

[Neil deGrasse Tyson]

The only counterpart particles are antimatter.

[Chuck Nice]

That's it.

[Neil deGrasse Tyson]

Yeah. There's no other.

[Chuck Nice]

That's what I'm saying.

[Neil deGrasse Tyson]

And there's not much antimatter in the universe, right. In fact, well, other than the centers of stars, we probably make all the antimatter there is in the universe on Earth, would you say?

[Brian Greene]

I haven't done the calculation, but I can imagine that.

[Neil deGrasse Tyson]

I mean, just think about that, right? There's plenty of antimatter made in the center of.

[Brian Greene]

Most antimatter in the universe will get

[Neil deGrasse Tyson]

annihilated finding matter immediately in the centers of the sun. So the cool part was in one of the Dan Brown stories, the Catholic church had a vial of antimatter that they carried.

[Chuck Nice]

That's so funny. Dominus dispir. Oh, he's gone. Physics just jokes, people.

[Neil deGrasse Tyson]

All right, so, yeah, I don't. I'm not quite clear if it met its. The counterpart it would annihilate. No matter what else is going.

[Chuck Nice]

No matter what else is going on.

[Neil deGrasse Tyson]

Yeah, yeah.

[Chuck Nice]

All right, so here we go. Kenny Watts says this. Hey, Dr. Tyson, Dr. Green. Sup, Lord. Nice. Kenny from Dothan, Alabama. Is the reason why we can't reach the absolute zero degrees in temperature because of the CMB? Is it due to the act of time using energy to move forward, creating heat? And if we were to reach absolute zero degrees, would space time move forward in that region?

[Neil deGrasse Tyson]

So my understanding of absolute zero is that all particle motion stops. Except it doesn't because you have quantum fluctuations even at absolute zero.

[Brian Greene]

That's the key point right there. That's the real barrier.

[Neil deGrasse Tyson]

Okay, so. But why is it. Isn't the cosmic microwave background a barrier?

[Brian Greene]

Well, if you didn't shield yourself from 2.7 degree photons, they would influence. But presumably if you're able to shield your environment.

[Neil deGrasse Tyson]

Yeah, but the shielding would have to be temporary because the. The heat transfers.

[Brian Greene]

Yeah, sure. But an experiment takes place over a period of time. So as long as your time scales, that's what.

[Neil deGrasse Tyson]

How a thermos works.

[Brian Greene]

Yeah. So I think it's really. The uncertainty principle is a true barrier against truly having particles at a definite location. Not Moving, that would mean position and speed were both nailed down at the same time.

[Chuck Nice]

You're not going to do that.

[Neil deGrasse Tyson]

Not happening.

[Chuck Nice]

Wow.

[Brian Greene]

Yeah.

[Chuck Nice]

So the wave function would cease to exist if you were ever to get to the place where you could get the particle to stay exactly frozen, like still and than definable in one point.

[Neil deGrasse Tyson]

Okay, so what is the temperature of that state of matter?

[Brian Greene]

Well, it depends on the details. I mean, you can calculate the quantum fluctuations of a field, and if you tell me how it interacts and its mass, you can calculate its quantum fluctuations. And indeed, that's how you make predictions about the Casimir effect, where you have, you know, two metal plates and there's empty space between them evacuated completely. And yet those plates can. Can pull together because the fluctuations of the field inside are a little bit less than the fluctuations outside. And that imbalance, you can actually calculate it and you can determine how the plates come together.

[Chuck Nice]

That is so freaky, man.

[Neil deGrasse Tyson]

It's all freaky.

[Chuck Nice]

That is so freaky. I love it.

[Neil deGrasse Tyson]

It's all freaky.

[Chuck Nice]

Oh, my goodness. And then they attract.

[Neil deGrasse Tyson]

Yeah, yeah, yeah, Brian, you freaky dude. So we should do this every week. What do you think? No, Brian, you have a life. Thank you, Brian.

[Brian Greene]

My pleasure.

[Chuck Nice]

This is great.

[Neil deGrasse Tyson]

You're working on a quantum physics book.

[Chuck Nice]

Yep, yep.

[Neil deGrasse Tyson]

This is the decade, the centennial decade of the discovery of quantum physics, so.

[Brian Greene]

Exactly.

[Neil deGrasse Tyson]

We can't have too much quantum physics out there. Yeah. And this is for the general public.

[Brian Greene]

Yeah. So we're finishing it up now. In 2027, it should be out.

[Neil deGrasse Tyson]

Get it out in this decade.

[Brian Greene]

Yeah, that's the key thing.

[Neil deGrasse Tyson]

Okay. All right. And this year we're recording this in 2026. This is the centennial of Edwin Hubble discovering that the Milky Way is not the only galaxy in the universe.

[Chuck Nice]

Wow.

[Neil deGrasse Tyson]

He discovers that Andromeda is not just a fuzzy spiral sitting within our stars. It's a whole other island universe out there.

[Chuck Nice]

I love that.

[Neil deGrasse Tyson]

That was a hundred years ago. So this has been a special edition because it's an extended DID conversation with my friend and colleague Brian Green, right up the street at Columbia University. And delight. Thanks for spending the afternoon in my office.

[Brian Greene]

My pleasure. It was great fun.

[Neil deGrasse Tyson]

All right. And Chuck, always a pleasure, baby.

[Chuck Nice]

Yes.

[Neil deGrasse Tyson]

And catching you on YouTube. Were you just smart enough?

[Chuck Nice]

That's right. On the StarTalk YouTube channel.

[Neil deGrasse Tyson]

Were you just smart enough for this conversation Today?

[Chuck Nice]

I was the dumbass. And happy to be so.

[Neil deGrasse Tyson]

All right, till next time, Neil Degrasse Tyson. Keep looking up.

[Brian Greene]

Eczema is unpredictable, but you can flare less with ebglis, a once monthly treatment for moderate to severe eczema after an initial four month or longer dosing phase. About four in ten people taking Emplis achieved itch relief and clear or almost clear skin at 16 weeks, and most of those people maintain skin that's still more clear at one year with monthly dosing. Emplus Lebricizumab LBKZ, a 250mg injection, is a prescription medicine used to treat adults and children 12 years of age and older who weigh at least 88 pounds or 40 kilograms with moderate to severe eczema, also called atopic dermatitis that is not well controlled with prescription therapies used on the skin or topicals, or who cannot use topical therapies. EPGLIS can be used with or without topical corticosteroids. Don't use if you are allergic to epglis. Allergic reactions can occur that can be severe here. Eye problems can occur. Tell your doctor if you have new or worsening eye problems. You should not receive a live vaccine when treated with ebglis before starting epglis, tell your doctor if you have a parasitic infection. Ask your doctor about ebglis and visit epgliss.lily.com or call 1-800-lilyrx or 1-800-545-5979

[Neil deGrasse Tyson]

and

[Brian Greene]

Doug, there's nowhere I wouldn't go to help someone customize and save on car insurance with Liberty Mutual. Even if if it means sitting front

[Chuck Nice]

row at a comedy show.

[Brian Greene]

Hey everyone, check out this guy and his bird. What is this, your first date? Oh no. We help people customize and save on car insurance with Liberty Mutual together. We're married. Me to a human, him to a bird. Yeah, the bird looks out of your league anyways. Only pay for what you [e-mail] Liberty Liberty Liberty Liberty.