Joe Rogan Experience #1631 - Brian Greene

1. 0:00 – 2:11

   Cosmic timescales, human “cameo,” and the mindset of a physicist

   1. NANarrator0:00

      (drumming music) Joe Rogan podcast, check it out. The Joe Rogan Experience.

   2. JRJoe Rogan0:06

      Train by day, Joe Rogan podcast by night. All day. (rock music) Mr. Greene, how are you, sir?

   3. BGBrian Greene0:16

      Good. How about you?

   4. JRJoe Rogan0:17

      Good to see you, man.

   5. BGBrian Greene0:18

      Good seeing you.

   6. JRJoe Rogan0:18

      What's the latest? You got a book out?

   7. BGBrian Greene0:20

      I do, yeah. The paperback of Until the End of Time is out today.

   8. JRJoe Rogan0:24

      U- Until the End of Time.

   9. BGBrian Greene0:25

      Yeah.

   10. JRJoe Rogan0:26

       That's, uh, that's heavy.

   11. BGBrian Greene0:28

       It is heavy. But it's, uh, it's a big story, but it's one that we have a nice part within, a small cameo. The human species has a cameo, so it's a, it's a human story too.

   12. JRJoe Rogan0:38

       Yeah, the human species, uh, what have we been around for, what, 300,000 years? 400,000 years?

   13. BGBrian Greene0:42

       It depends how you define the species. But yeah, that's not a bad number. Some people go back to a million or so, if you go back to early human species. But yeah, and compared to the length of time scales that compose reality from the beginning to the end, that's zero. That's nothing.

   14. JRJoe Rogan0:58

       When you... Uh, being a physicist, being a person that really does have a, a much greater grasp of the concept of infinity and of time and of the, the, just the length that the universe has existed in its current form, how do you just get through your day and not freak out? (laughs)

   15. BGBrian Greene1:18

       Well, it's because my wife says, you know, "You gotta cook dinner."

   16. JRJoe Rogan1:21

       (laughs)

   17. BGBrian Greene1:21

       So, I mean- (laughs) They're, they're things that-

   18. JRJoe Rogan1:23

       You gotta be in the moment.

   19. BGBrian Greene1:24

       They're things that you have to actually get done. But it does change your perspective in, in a significant way, because you recognize that the things that we consider to be oh, so vital and important are just this blink of an eye on the cosmological landscape-

   20. JRJoe Rogan1:41

       Yeah.

   21. BGBrian Greene1:41

       ... on the cosmological timeline, and it does change the way you approach the world when you pay attention to it. It's hard to always pay attention to it, though. Look, I mean, if I'm walking down the street and I'm thinking about quantum mechanics, I'm thinking about, you know, quantum tunneling. I'm thinking about relativity, time slowing down when I'm moving, right? So, if you're in the physics mode, you are living life differently, but who can live that way for more than a moment?

   22. JRJoe Rogan2:04

       Right.

   23. BGBrian Greene2:05

       Because life is too powerful in its intrusion on the way you actually behave in the world.

2. 2:11 – 4:36

   Science communication: curiosity vs. misinterpretation and quantum “woo”

   1. JRJoe Rogan2:11

      But because of your perspective and because of your education on this, do you feel, like, almost an obligation to try to expand people's perspective?

   2. BGBrian Greene2:21

      I'd say that it's part of one of my goals of life is to do just that. You know, I don't want people to not live their lives the way they have, but I want them to be able to broaden the experience by recognizing that everyday phenomenon is a small (laughs) slice of the way the world is actually put together. And, and when you can see your life and your experiences just a tiny sliver of a reality that's, like, bizarrely strange and utterly wondrous, when you understand everything, you know, from black holes to time dilation to quantum tunneling, to all that stuff that we have discovered over the last couple hundred years, yeah, it changes things.

   3. JRJoe Rogan3:02

      Is it, uh, is it a difficult thing to get across to people? Like, do you try to think, like, what is the best way that people are gonna absorb these ideas? Because they are so-

   4. BGBrian Greene3:11

      Yeah.

   5. JRJoe Rogan3:12

      They're not abstract, but they're, th- they're so outside of the norm in terms of the way people view the world.

   6. BGBrian Greene3:19

      Yeah, yeah.

   7. JRJoe Rogan3:19

      You kinda like go, "Hey, I know you're concentrated on this, but look at that."

   8. BGBrian Greene3:24

      Yeah. I mean, the real difficulty is not so much getting people interested. You might think that that's the big hurdle. People are like, "Ah, don't talk to me about (laughs) that stuff, it doesn't matter to my life." But that's... No, people are very curious and interested in what physics has found. What's hard is getting them to not just take it in, but to take it in correctly.

   9. JRJoe Rogan3:46

      Hmm.

   10. BGBrian Greene3:46

       So that they don't take the ideas and twist it into something else that suits whatever weirdness they may have encountered in the world. The number of times that I see people take the concepts of quantum mechanics and turn it into utter nonsense-

   11. JRJoe Rogan4:01

       Okay, yeah.

   12. BGBrian Greene4:01

       ... because they're like, "Hey, oh, yeah, probabilities. Okay, you know, that describes this quality of my world," or, you know, "The weirdness is the time. Yeah, that's why I had this, like, mind meld with my best friend on the other side of the..."

   13. JRJoe Rogan4:12

       (laughs)

   14. BGBrian Greene4:13

       You know, that sort of thing.

   15. JRJoe Rogan4:14

       Yeah.

   16. BGBrian Greene4:14

       And, and, and I, I don't, I don't fault people for that. These ideas are difficult. But if you ask me what the challenge is, the challenge is breaking through that and getting people to really understand what it is that we found. And it's weirder than many of the things that the human imagination would go to, but it's harder because it's very specific and rigorous and mathematical, ultimately, and that's unfamiliar.

3. 4:36 – 8:46

   ‘What the Bleep’ and cultish co‑opting of physics (Ramtha story)

   1. JRJoe Rogan4:36

      Do you think it's the complications of quantum mechanics, like the co- it's that it's so, it's such a bizarre field of study that it sort of lends itself being sort of occupied by people like the What the Bleep Do We Know? type folks-

   2. BGBrian Greene4:52

      Yeah.

   3. JRJoe Rogan4:52

      ... that kinda co-op, co-opt it and then spread nonsense?

   4. BGBrian Greene4:56

      It's exactly right. I mean, that, that, that film is a, is an unfortunate- (laughs)

   5. JRJoe Rogan5:00

      (laughs)

   6. BGBrian Greene5:00

      ... but very good example of people who took the ideas and, and usurped them-

   7. JRJoe Rogan5:06

      Yeah.

   8. BGBrian Greene5:06

      ... for their own purpose, right? Um, I had friends that are in that film who were deeply disheartened by the way their words were twisted.

   9. JRJoe Rogan5:15

      Well, they were tricked. Right?

   10. BGBrian Greene5:15

       They were tricked, yeah.

   11. JRJoe Rogan5:16

       They, they thought-

   12. BGBrian Greene5:17

       Uh, uh.

   13. JRJoe Rogan5:17

       ... they were doing a documentary on quantum mechanics-

   14. BGBrian Greene5:19

       Yeah.

   15. JRJoe Rogan5:19

       ... and it turned out to be essentially a cult documentary.

   16. BGBrian Greene5:21

       Exactly.

   17. JRJoe Rogan5:22

       Yeah.

   18. BGBrian Greene5:22

       And, and, and so there is a, a sensibility of that sort which is volitional. That's like a choice, I think, that was made. In fact, I think I mentioned to you once. The director of that film had called me to be in it, and I was like, "Whoa, what are you doing?"

   19. JRJoe Rogan5:36

       Mm-hmm.

   20. BGBrian Greene5:36

       'Cause I couldn't tell what the... And then he called me like a year after the film came out and kind of apologized and said, "You were right."

   21. JRJoe Rogan5:43

       Oh, so he didn't know?

   22. BGBrian Greene5:44

       I kinda... Yeah, he didn't know.

   23. JRJoe Rogan5:45

       Oh.

   24. BGBrian Greene5:45

       So, so, so, but, but yeah-

   25. JRJoe Rogan5:46

       We should, we should stop just so people that don't know what we're talking about understand what's happening. There is a person in that documentary that calls themselves Ramtha that, uh-There's a p- they don't explain it in the documentary, but they claim to be, like, uh, what is it? A thousand-year-old...

   26. BGBrian Greene6:04

       35,000-year-old sage from the lost land of Lemuria, I believe it is-

   27. JRJoe Rogan6:10

       (laughs)

   28. BGBrian Greene6:10

       ... which is, like, another lost land with Atlantis. They were, like, at war with Atlantis-

   29. JRJoe Rogan6:14

       Ah.

   30. BGBrian Greene6:14

       ... or something like that. Um, so yeah. It, it's, it's a pretty deep cult.
4. 8:46 – 13:07

   Quantum entanglement: spooky correlations, math vs. intuition, and how we know it’s real

   1. BGBrian Greene8:46

      A- and I have to say, though, we physicists come to the very same place. We say, "What is the world, then?"

   2. JRJoe Rogan8:51

      Yeah.

   3. BGBrian Greene8:51

      "What are we talking about?" And the difference is, we can then look back at the equations and say, if we're talking about quantum entanglement, we can see how two particles far apart in space will have behaviors that are correlated. You do something on this particle, and it will have some instantaneous correlation with what happens at that particle, regardless of how far apart they are in space.

   4. JRJoe Rogan9:13

      Mmm.

   5. BGBrian Greene9:13

      Einstein himself called this spooky.

   6. JRJoe Rogan9:16

      Yeah.

   7. BGBrian Greene9:17

      Spooky action at a distance. You do something in New York, and it affects, in some quantum mechanical way, a particle in California. How could that be?

   8. JRJoe Rogan9:25

      How can that be?

   9. BGBrian Greene9:26

      Good. So, I don't know at some level if I'm trying to answer you human-to-human. But if I'm answering as a mathematician, as a physicist, I can see it in the equations. I see it in the mathematics. I see how this particle has a quantum wave which has a piece that stretches all the way out to California and way beyond, and when I interact with this particle, I affect that probability wave instantaneously. Therefore, I change the wave in California even if my action is in New York. So, I see that in the mathematics.

   10. JRJoe Rogan9:57

       I understand these words you're saying-

   11. BGBrian Greene9:59

       Yeah.

   12. JRJoe Rogan9:59

       ... but I don't understand it. Like, in terms of-

   13. BGBrian Greene10:00

       Neither do I.

   14. JRJoe Rogan10:01

       (laughs)

   15. BGBrian Greene10:01

       But that's the point. (claps) You know, so-

   16. JRJoe Rogan10:04

       Uh-

   17. BGBrian Greene10:04

       So, it's, it's, it's, uh, what level of understanding are we, are we talking about, right? If you're talking about intuition, like a deep intuition, the way we understand two plus two is four, right? I don't have to explain that to anybody.

   18. JRJoe Rogan10:15

       Right.

   19. BGBrian Greene10:15

       They get it. They see two apples and two apples are four. They got it. But when it comes to quantum entanglement, I don't feel it that way. I don't have that intrinsic understanding of what it is. And so, if you push me to say, "Well, what is it?" I ultimately fall back on the math.

   20. JRJoe Rogan10:33

       Right.

   21. BGBrian Greene10:33

       And ultimately, I say the reason I believe the math is 'cause the math makes predictions that we can test in the laboratory. And then you say, "Well, then what kind of understanding is that?" And some people would say that's the deepest understanding. All we really want of a physical theory is for it to give a rigorous mathematical articulation of what happens out there in the world, and it's the human brain struggling for some kind of intuition. That's our problem. That's a human problem.

   22. JRJoe Rogan11:02

       Right.

   23. BGBrian Greene11:02

       That's not a problem of physics. That's a problem of us being satisfied.

   24. JRJoe Rogan11:06

       A problem of perception and understanding.

   25. BGBrian Greene11:08

       Perception and understanding, yeah.

   26. JRJoe Rogan11:08

       Yeah, so this spooky action at a distance, why was it first wha- what... Was it a hypothesis, or was this something that was, was proven by math first? Like-

   27. BGBrian Greene11:20

       Yeah. So, so Erwin Schrodinger, one of the founding fathers of quantum mechanics, a curious fella, uh, a very interesting life, but he realized looking at the equations that there was this quality of the math that if two particles come together and they interact for a little while and then they separate, they can no longer be thought of as independent or autonomous. I mean, the very basic quality of autonomy, you and I are autonomous because we can separate. We can go our separate ways and do whatever we want at our respective locations. So, you would think that if two particles separate...They will also be autonomous. But he saw it in the mathematics that they would not be autonomous, that what you did to one would have an effect in some quantum mechanical way on the other. Now, he saw that in the mathematics. He called it out as the central feature of quantum mechanics, and that's a big statement coming from him because there are a lotta other weird qualities of quantum physics. Einstein then comes along, 1935 with two colleagues, and leverages this idea, writes a paper where he tries to prove that quantum mechanics cannot be the full story of the world because of this weird quality of what you do here affecting something over there. It's not until the 1980s that people really start to test this idea. And by today, this is used all the time in the laboratory. Quantum computing makes use of this quality. So, this is no longer an idea that's abstract. It's something that's applied. Applied quantum entanglement gives us things in the real world in the laboratory, so this is beyond question real, even though Einstein thought it couldn't be and Schrodinger considered it to be the strangest feature of the math of all.

   28. JRJoe Rogan13:05

       So, beyond question, it's real.

   29. BGBrian Greene13:07

       Yeah.

5. 13:07 – 23:30

   Interpretations: many‑worlds, ‘shut up and calculate,’ and wormholes as a possible mechanism

   1. JRJoe Rogan13:07

      But what do you think is happening?

   2. BGBrian Greene13:09

      Well, so, m- if you're going to allow for the most exotic possibilities, some would suggest that you are probing the many worlds of quantum mechanics. So, in quantum mechanics, all you ever do is predict the probability of this happening or that happening. Electrons, you know, 70% chance here, 30% chance here. If you measure the electron and you do find it over here, what happened to the other possibility? Some say it happens, but just in another world. In one world, you find the particle here. In another world, there's a copy of you that finds the particle over there. Each of yous doesn't know about the other and thinks you are the unique version of you, the unique Joe Rogan, but now there are two of you, each thinking that the particle was found in one location or another. If that's the way quantum mechanics actually works, and some people do think this, then quantum entanglement is, in some sense, less weird because what happens is that in one world, you have a certain correlation between the particles. In another world, you'd have a different correlation between the particles, and that's just what happens. So, that's one, but, you know, you're, you're, you're, you're, you're, you're allowing multiple universes-

   3. JRJoe Rogan14:20

      Yeah.

   4. BGBrian Greene14:20

      ... in this explanation. That's, that's pretty weird in its own right. Um, the fundamental way that we encapsulate this, we say that quantum mechanics is non-local. Non-local means that the influences are not limited to where they are applied. Our experiences... Look, if I do something to this bottle of water, the influence is in this local neighborhood. What I did just now didn't affect something on the other side of Austin or on the other side of the world. But quantum mechanics is saying that that's an intuition built up from everyday experience, and everyday experience is grossly misleading-

   5. JRJoe Rogan14:57

      Ooh.

   6. BGBrian Greene14:57

      ... when it comes to this kind of an idea.

   7. JRJoe Rogan14:59

      Severely limited.

   8. BGBrian Greene15:00

      Severely limited.

   9. JRJoe Rogan15:02

      And this concept of many worlds, so the idea is that there's multiple versions of you and multiple versions of everything that you've experienced, all the things that you see that you consider to be Austin, Texas, or the United States, or the, the world itself.

   10. BGBrian Greene15:19

       Yeah.

   11. JRJoe Rogan15:19

       There's multiple versions of this happening simultaneously. How many?

   12. BGBrian Greene15:23

       Well, in some sense, infinite-

   13. JRJoe Rogan15:25

       Oh, boy.

   14. BGBrian Greene15:25

       ... because the, the basic idea is that any outcome that is allowed by the laws of quantum physics, any outcome will take place in its own separate world. And so, when you think about every decision you've ever made, every possibility that you've ever encountered, all of the outcomes happen, and that would happen throughout all of time. So, in some sense, there's an unending number of realities that are in the grand landscape of the quantum description. Now, we hear that, and you say, "That's nuts. That sounds nutty," right? We experience one world. But if you look at the mathematics, as a guy named Hugh Everett did in 1957, he was a graduate student at Princeton, unknown, and he looked at the math. And he said, "I wanna look at the math and give it the most straightforward intrinsic interpretation." And the most economical intrinsic interpretation of the math is this one. It sounds grossly uneconomical, all these universes, but that's an output. The input is incredibly economical. You look at the equations, and this is the most straightforward interpretation. Every outcome does happen. It happens in its own world. Now, I'm not saying that I believe this, but it's definitely a worthy contender for the way that we should think about quantum mechanics.

   15. JRJoe Rogan16:47

       So, do you guys get together and bounce these ideas off each other o- on a regular basis? Like-

   16. BGBrian Greene16:53

       I- it depends who you mean by you guys.

   17. JRJoe Rogan16:54

       Y- you physicists tell us-

   18. BGBrian Greene16:55

       You, you physicists. Well, yeah, it's-

   19. JRJoe Rogan16:57

       (laughs)

   20. BGBrian Greene16:58

       So, only some. So, some physicists, when they hear about this kinda talk, they roll their eyes, and they say, "Just use the mathematics. Make predictions for what we'll see at the Large Hadron Collider. Make predictions for what we'll see in this or that laboratory. Don't try to understand it. Just do it." You know, it's the cold, so-called shut up and calculate approach-

   21. JRJoe Rogan17:21

       Hmm.

   22. BGBrian Greene17:21

       ... to quantum mechanics. And Niels Bohr, who was one, again, one of the founding pioneers of quantum mechanics, this was his perspective. I mean, Bohr basically said the goal of physics is not to tell us how the universe is in the sense of understanding it, it's just to make (laughs) predictions that we're gonna see in experiments. That's all that you should ever expect to do. There are other physicists who don't feel that way. And there are other physicists who think physics is a matter of telling us what's happening.

   23. JRJoe Rogan17:49

       Yeah.

   24. BGBrian Greene17:50

       It's gotta give us the story. It's gotta, like, peel back the curtain and give us a clear glimpse of what's happening behind the scenes. And so those of us who do have that as the goal-... do get together and-

   25. JRJoe Rogan18:02

       (laughs)

   26. BGBrian Greene18:02

       ... do talk about these things. (laughs) You know.

   27. JRJoe Rogan18:03

       Well, I'm glad you guys exist, because those shut up and do the math, and-

   28. BGBrian Greene18:07

       Yeah.

   29. JRJoe Rogan18:08

       ... those guys, they're not gonna help me. Like, that-

   30. BGBrian Greene18:10

       Yeah.
6. 23:30 – 30:08

   From understanding to engineering: integrated circuits, entanglement as spacetime “threads,” and experiments

   1. JRJoe Rogan23:30

      So, that's the concept of use, using these principles and this understanding of quantum mechanics to manipulate reality itself.

   2. BGBrian Greene23:37

      Yeah. Yeah. Now, how far-

   3. JRJoe Rogan23:38

      How do you anticipate that playing out?

   4. BGBrian Greene23:41

      That's a tough one. I don't know. You know, uh...It's, uh, it'll certainly be something that we approach in an incremental way. I'm not suggesting that, you know, tomorrow (laughs) we're gonna be developing terraforming new worlds or creating parallel universes. But there's a pattern that we certainly see playing out throughout the history of science, which is this. You're presented with some quality of the world, you don't understand it. You then experiment, you observe it. And then little by little you begin to understand it, you develop theories. Mathematical ideas being the most precise ones to describe whatever it is that you're talking about. And once you have those ideas nailed down, you can then use them to manipulate the world. That's what we do with quantum mechanics. At first, we just wanted to understand atoms, right?

   5. JRJoe Rogan24:26

      Right.

   6. BGBrian Greene24:26

      Particles and things of that sort. Now, we can manipulate the quantum world to create, you know, all sorts of technological wonders, the integrated circuit, which is at the core of every technological gadget that has transformed life on Planet Earth. This is quantum mechanics in the hands of human beings. And so that pattern of going from lack of understanding, to understanding, to manipulation is the pattern that will continue to play out going forward. So, that manipulation, w- what will it be? Well, I think, uh, we're gonna come to a time when we understand the structure of space far better than we do now. The structure of time far better than we do now. Does that suggest that we'll manipulate space and time if the pattern persists? Yeah. Now, what does that mean? Will we build our own wormholes? I don't know. I don't know. That's starting to go into crazy land, the woo that we were talking about-

   7. JRJoe Rogan25:19

      Mm-hmm.

   8. BGBrian Greene25:19

      ... before. But-

   9. JRJoe Rogan25:19

      But maybe it won't be woo 100 years from now.

   10. BGBrian Greene25:21

       Or, or a thousand years from now.

   11. JRJoe Rogan25:23

       Right.

   12. BGBrian Greene25:23

       And if we stick around long enough, if the pattern persists, that understanding ultimately gives you the lever to manipulate, right now if you ask me what's happening at the cutting edge of string theory, quantum mechanics, it's understanding black holes. It's understanding how quantum mechanics and black holes talk to each other. And what is black hole? A black hole is a weird region of spacetime. So, we're trying to understand spacetime itself at the deepest possible level. And so, the next step would suggest that we will manipulate it at some point in fairly significant ways.

   13. JRJoe Rogan25:56

       So, the ways we've used it so far, you, you mentioned integrated circuits, how, how is quantum mechanics used to u- to form integrated circuits?

   14. BGBrian Greene26:05

       So, an integrated circuit, in essence, is a little device in where you want an electron to follow a very specific trajectory to carry out this or that computation or process. Now, if you wanna control electrons with that level of fidelity, you've got to use the mathematical laws that describe electrons with that level of fidelity. Newton's equations from the late 1600s, they won't work. If you think of the electron as a little baseball or a little billiard ball, totally inaccurate. It will not allow you to manipulate their motion. But with quantum mechanics, you can manipulate the motion of the electrons because you understand their mathematical underpinnings. And so it was only by applying quantum mechanics to materials, to structures that could give rise to this kind of control over little particles that we could build these microscopic circuits. And they work.

   15. JRJoe Rogan26:54

       Mm-hmm.

   16. BGBrian Greene26:55

       I mean, that's, that's the proof in the pudding, right? And so that's a, a key example of quantum mechanics transforming the world as we know it. And right now, there is work in string theory that is suggesting that this notion of quantum entanglement that we were talking about before, that may be the key to understanding the fabric of spacetime itself. I mean, we use this metaphor fabric of spacetime, right?

   17. JRJoe Rogan27:24

       Mm-hmm.

   18. BGBrian Greene27:25

       But any piece of fabric, it's stitched together by threads, right? So, what are the threads of the spatial fabric if we push this metaphor and try to really understand it more fully? And one of the suggestions is, the threads of quantum entanglement that tie distant objects together, those may be the threads that hold together the fabric of spacetime itself.

   19. JRJoe Rogan27:48

       So, that would mean that everything is somehow connected, even if it's 13.7 billion light years away. These things are somehow or another directly connected.

   20. BGBrian Greene28:00

       Yes. Now, to avoid that turning into the woo-

   21. JRJoe Rogan28:04

       Right.

   22. BGBrian Greene28:04

       ... you have to realize that when you have a lot of material, and when you have a lot of time and a lot of space, these quantum entangled connections become so spread out, that they become diluted. So, it's not as though someone can say, "You know, I thought about my best friend in California, then the phone rang. We must be quantum entangled." That's the sort of stuff-

   23. JRJoe Rogan28:26

       Mm-hmm. Yeah.

   24. BGBrian Greene28:26

       ... that, that this kinda talk can lead to. But, but fundamentally what you're saying is correct. It may be the structures in space may be fundamentally connected through these quantum entanglements, and it may be that the substrate, space itself... We don't usually think of space as something because it's kind of invisible. But we're within the fabric of spacetime itself, and that arena may be stitched together by these threads of quantum entanglement as well.

   25. JRJoe Rogan28:55

       So, this quantum entanglement will be diluted at a distance? So, is that... What, what, what is the mechanism behind that?

   26. BGBrian Greene29:02

       It's more, it's more diluted by the number of particles that are involved.

   27. JRJoe Rogan29:06

       Okay.

   28. BGBrian Greene29:06

       So, if you just have two particles in a pristine environment, like a total vacuum, and they're entangled, you can move them arbitrarily far apart and the entanglement will not dilute. That's the craziness. You could have two particles on opposite ends of the universe, and you measure one and the other-

   29. JRJoe Rogan29:23

       How is that done? Like, how, how, how-

   30. BGBrian Greene29:24

       Yeah, good. Yeah, how do you do that? And there are a number of experimental protocols, procedures, but one concrete one is you take an atom, like an atom of calcium is one example. You fire some laser on it, and that excites the electron in the calcium atom to a higher energetic state.When that electron falls back down to a lower energetic state, it emits photons back to back. And because those photons were emitted from the same process, the electron falling down to a lower energy state, those photons will be entangled. So, that's a concrete way where you can have back-to-back photons that will travel arbitrarily (laughs) far apart if they don't encounter anything else, that will be quantum entangled.

7. 30:08 – 40:41

   Quantum computing: qubits, coherence, error correction, and what it could change

   1. JRJoe Rogan30:08

      (smacks lips) Now, you were talking about integrated circuits. Now, I hear a lot of talk about quantum computing-

   2. BGBrian Greene30:16

      Yeah.

   3. JRJoe Rogan30:17

      ... and I don't understand what that is, but everybody's telling me that it's gonna revolutionize computing.

   4. BGBrian Greene30:21

      Yeah.

   5. JRJoe Rogan30:21

      How so?

   6. BGBrian Greene30:22

      Well, with- as with everything, you have to interrogate precisely what one means by revolutionize everything. Maybe in some rough sense that's true. But let me just first say what it is-

   7. JRJoe Rogan30:33

      Okay.

   8. BGBrian Greene30:33

      ... and then say what the possibilities are. So, imagine that you have a computer that can access, I'll use one particular lang- access the many worlds of quantum mechanics. Now, when you're carrying out a calculation, you don't have the calculation solely take place in one universe, you have it take place in a whole collection of parallel universes, allowing you in some sense to divide up the calculation, and in parallel have it take place across this spectrum of universes. Clearly that will rapidly speed up the calculation because now it's no longer happening in one universe, you split it across many universes. So, in some sense, quantum computing is trying to leverage that quality of quantum mechanics. Now, that's one language using the language of many worlds. You don't have to use the language. You can also use just the language of probabilities. So, if you have a particle, like an electron, normally in a classical world you'd say it's either here or there. In a quantum world, our world, it can be in a mixture of here and there. If it's in a mixture of here and there, you can do calculations here and there. Whereas in a classical world you could either do the calculation here or there. So, it's basically substantially increasing the places where calculations take place, thereby substantially decreasing the amount of time that it takes these calculations to be accomplished.

   9. JRJoe Rogan32:09

      And but- by what mechanism? Like, what is- what separates quantum-

   10. BGBrian Greene32:13

       Yeah.

   11. JRJoe Rogan32:13

       ... computing from regular computing? How is it-

   12. BGBrian Greene32:14

       Yeah, so- so, in regular computing, you- you have quantum qualities, because like I said, the integrated circuit, you need it to understand quantum mechanics to guide the motion of the particle through the integrated circuit. But in the end of the day, a traditional computer, a classical computer if we will, stores information as bits, zeros and ones. So, you have one bit that's either a zero, another bit that's either a one, and through that you can store information and manipulate information, and that's what computation is all about. The quantum computer changes the bit to the so-called qubit. What is a qubit? A qubit is a specially defined and constructed digit that can be in a mixture of zero and one. And specifically, the way we usually do this is we have what are known as spin systems. So, an electron has a spin, like a little top, and it can either spin counterclockwise that we call spin up, or clockwise that we call spin down. In a classical world, the electron is either this or this. In the quantum world, it can be a mixture. And so literally these quantum computers have these spin systems that are in these mixtures of up and down simultaneously, and that allows them to do multiple computations simultaneously that allows them to decrease the time it takes to carry out the computation. That's- that's the essence of the idea.

   13. JRJoe Rogan33:40

       Is the structure of the computer different? Like-

   14. BGBrian Greene33:42

       Totally.

   15. JRJoe Rogan33:42

       So, regular computer has a motherboard-

   16. BGBrian Greene33:45

       Yeah.

   17. JRJoe Rogan33:45

       ... it has a processor, it has a hard drive. What is a quantum computer structured like?

   18. BGBrian Greene33:49

       You know, if you see some of these things, they look... I've heard them described, and it's not a bad description, as sort of like chandeliers. You- you've got spin systems in arms of the chandeliers, and you have cooling systems that are vital to these computers because if there's heat that comes into the system, it can destroy this delicate mixture of up and down simultaneously. So, they're far more delicate, and it is much more difficult to, at this stage, have the number of bits. So, an ordinary c- computer can have as many bits as you want. As you say, just, you know, put more boards, expand, you know, the random access memory. You know, it's all up to you, the user. For quantum computers, you've gotta make sure that all these qubits are working together in order that they can perform these calculations. And it's very hard to have a whole lot of qubits maintain the so-called quantum coherence that allows them to work together. So, the maximum number of qubits in quantum computers that have been built, it's only at 50. Very small relative to the number of bits that we're familiar with, you know, in... We're talking about gigabits, right-

   19. JRJoe Rogan35:01

       Mm-hmm.

   20. BGBrian Greene35:01

       ... when you're talking about your- your billions of bits. So- so that is for the future, but there doesn't seem to be a fundamental obstacle to building a quantum computer that has, you know, a large number of these qubits, and in that way in principle being able to do calculations exponentially more quickly. That's the rough idea.

   21. JRJoe Rogan35:19

       How far away are we from implementing quantum computing in daily life? Like is it- i- d- is it a cooling issue? Is it a- an issue of just, uh, m- expanding our- our understanding of how to construct these things? Like-

   22. BGBrian Greene35:32

       Yeah. Um, there are- there are those in the field who are careful to say that they don't think that we'll ever have quantum computing in everyday life. And the reason for that is largely, you know, the- the cooling issue-

   23. JRJoe Rogan35:47

       Mm-hmm.

   24. BGBrian Greene35:48

       ... and it has to do with the...... difficulty in maintaining the stability of these devices. They're so delicate. Whereas, you know, you drop your laptop, you may crack it or something. But, you know, for the most part, you drop your phone and it's fine.

   25. JRJoe Rogan36:02

       Mm-hmm.

   26. BGBrian Greene36:02

       And so, there are those who say that we will never have these things in daily life. They'll always be highly specialized, you know, in laboratories that we somehow make use of, as opposed to carry around in our pocket. But the same was (laughs) said about ordinary computers, you know, 60, 70, 80 years ago, when a computer in those days filled an entire room-

   27. JRJoe Rogan36:21

       Right.

   28. BGBrian Greene36:21

       ... with all these vacuum tubes. Who ever thought that we'd be walking around in our pocket with something more powerful than that kind of device? So, I'm-

   29. JRJoe Rogan36:28

       Just 50 years later.

   30. BGBrian Greene36:29

       Yeah. So, I'm, I'm skeptical whenever I hear people say, "Never, never, never." But in this case, I'm almost open to the idea, because these systems are so incredibly delicate. And in fact, one of the hurdles right now in quantum computing is they're not reliable. These qubits, they can flip from one state to another, ruining your calculation very easily.
8. 40:41 – 1:01:39

   AI creativity and consciousness: art, shared learning, and the ‘inner world’ problem

   1. JRJoe Rogan40:41

      I think it's so interesting that we look to games to find out how intelligent and how powerful computers really are. Like, for the longest time it was could a computer beat a chess master.

   2. BGBrian Greene40:51

      Yeah.

   3. JRJoe Rogan40:52

      And now that, that, that problem has been solved. Like, not only can a computer beat a chess master, but they always will beat a chess master now-

   4. BGBrian Greene40:59

      Yeah.

   5. JRJoe Rogan40:59

      ... which is really fascinating to people.

   6. BGBrian Greene41:01

      Yeah, it totally is. And, and there's a way in which that makes a lot of sense, because what is a game? A game is an artificial universe with very simple rules. And therefore, it's a simplified version of reality.

   7. JRJoe Rogan41:15

      Hmm.

   8. BGBrian Greene41:15

      And it's also a well-posed game. I mean, tic-tac-toe versus chess, right? The difference is in tic-tac-toe, it's so simple that there's no creativity involved. You know, if you play it correctly, you'll always have a draw, right?

   9. JRJoe Rogan41:29

      Right.

   10. BGBrian Greene41:29

       But in chess, because of the great number of possibilities, there's a lot of creativity that comes into play. So, it's a, it's a universe with a fixed set of rules, it's simplified, and it has the opportunity for human beings to be creative.

   11. JRJoe Rogan41:41

       Hmm.

   12. BGBrian Greene41:42

       And so it's a wonderful testing ground for computers, because if a computer can beat a human in that domain, now we can say, "Aha, that computer, in some sense, is creative."

   13. JRJoe Rogan41:53

       Hmm.

   14. BGBrian Greene41:53

       And the thing that we usually...... look to, to define ourselves as human beings. How do we differ from other things in the world, the inanimate world? We're creative. Right? We can come up with ideas. We can come up with novel, innovative ideas. That's kind of how we define ourselves. And so, when a computer starts to do that, it starts to challenge our humanity.

   15. JRJoe Rogan42:16

       Mm.

   16. BGBrian Greene42:17

       And I think that's a good thing, right? I don't think that we are as different from the external world as we perhaps like to think. We are collections of particles governed by the laws of physics, and I think it's spectacular that a collection of particles under the ironclad rules of physics can be creative, can come up with ideas, can, can figure out quantum mechanics and general relativity. Like, how spectacular is that? But all we are are big collections of particles governed by those laws, and all a computer is, big collection of particles governed by those rules. So, I full well anticipate the possibility for a computer to get to our level of cognitive power and beyond, and I full well anticipate that there will be the artificial systems that say to us, "I have an inner world. I have conscious awareness." Now, how will we test that computer to see whether it was programmed to say that or whether it actually is having that inner world? I don't know. That's a tough one, but it's a question we face all the time. Like, I assume you have an inner world inside your head. I don't know that for a fact. You, I assume, are making the same assumption about me. How did we come to that? We come to it based on the fact that we're having a conversation, and we observe each other's behaviors, and all of that comes together to suggest that we are each roughly the same, and therefore I assume that what's happening inside your head is roughly the same kind of processes that happen inside of mine. We have to infer it, and we're gonna have to infer it for artificial systems too. And, you know, if you walk down the street and there's a artificial system sitting on a park bench, you know, hand on its head, saying, "I'm so worried. What's it all about?"

   17. JRJoe Rogan44:05

       (laughs)

   18. BGBrian Greene44:05

       You know, "What's, what's, what's life? What's..." And if it's real-

   19. JRJoe Rogan44:09

       Yeah.

   20. BGBrian Greene44:09

       ... you're gonna say, "Wow, that computer's having an existential crisis-"

   21. JRJoe Rogan44:12

       Mm.

   22. BGBrian Greene44:13

       ... "and, and there's a real inner world happening there." What other conclusion could you draw, you know?

   23. JRJoe Rogan44:18

       Yeah, the... I think we have a, an internal bias about our own uniqueness in terms of our abil'... 'Cause we're so unique in comparison to all the other animals in our ability to manipulate the world and our environment and, and our use of creativity.

   24. BGBrian Greene44:33

       Yeah.

   25. JRJoe Rogan44:34

       But it's really just variables.

   26. BGBrian Greene44:36

       Yes.

   27. JRJoe Rogan44:37

       And if you took into, like, a c- a computer, specifically a super powerful computer like what we're assuming a quantum computer could become, could take into account all the things that have ever been said by any human being ever, the motivations for those things, whether it's love, or emotions, or jealousy, or narcissism, or whatever these weird human quirks are, and they could figure out a way to create works of art.

   28. BGBrian Greene45:07

       Yeah.

   29. JRJoe Rogan45:07

       They could figure out a way to s- to do things that are uniquely moving to us, and that's what's gonna be really weird.

   30. BGBrian Greene45:14

       To-
9. 1:01:39 – 1:17:04

   Bio vs. tech evolution: Neuralink, changing norms, delegation of decisions, and ethics

   1. JRJoe Rogan1:01:39

      ... that is what's gonna lead us to become some sort of a symbiotic creature, some sort of a integrated computer/biological entity.

   2. BGBrian Greene1:01:48

      And is that a bad thing?

   3. JRJoe Rogan1:01:49

      I don't know if it's a bad thing.

   4. BGBrian Greene1:01:50

      Yeah, see, I don't think it's necessarily a bad thing.

   5. JRJoe Rogan1:01:52

      Oh, you're one of those... (laughs)

   6. BGBrian Greene1:01:56

      (laughs)

   7. JRJoe Rogan1:01:56

      I don't know. You might be right. Look, man-

   8. BGBrian Greene1:01:58

      You know-

   9. JRJoe Rogan1:01:58

      ... you know about, more about this shit than I do.

   10. BGBrian Greene1:01:59

       All I'm saying is, we've been on a particular evolutionary trajectory. And for a long time, it's been thoroughly biological and thoroughly by random mutations. If that now moves to a new phase in which we've got new kinds of materials and new kinds of ways of modifying the system that's not just random mutation and natural selection, so be it.

   11. JRJoe Rogan1:02:22

       Yeah.

   12. BGBrian Greene1:02:23

       You know.

   13. JRJoe Rogan1:02:23

       It seems like that's inevitable when you think about how we have this insatiable desire to innovate.

   14. BGBrian Greene1:02:28

       Yeah.

   15. JRJoe Rogan1:02:29

       It seems like it's inevitable. And, you know, I'm sure you're aware of Elon Musk's Neuralink and-

   16. BGBrian Greene1:02:33

       Yeah, sure.

   17. JRJoe Rogan1:02:34

       ... that it's gonna... They're initially gonna use it for, for people that have injuries and-

   18. BGBrian Greene1:02:37

       Yeah.

   19. JRJoe Rogan1:02:37

       ... diseases and neurological conditions, but-

   20. BGBrian Greene1:02:40

       That's how it always begins. (laughs)

   21. JRJoe Rogan1:02:42

       (laughs)

   22. GPGuest’s assistant/third participant1:02:43

       (laughs)

   23. BGBrian Greene1:02:43

       Yeah.

   24. JRJoe Rogan1:02:43

       But it seems, it seems inevitable.

   25. BGBrian Greene1:02:45

       Yeah.

   26. JRJoe Rogan1:02:45

       It seems like if, if we can manipulate matter and, you know, with CRISPR, we're manipulating genetics-

   27. BGBrian Greene1:02:50

       Yeah.

   28. JRJoe Rogan1:02:51

       ... it just seems inevitable that we're gonna one day be something unrecognizable.

   29. BGBrian Greene1:02:56

       Right. And the, the... That will happen in any event. It'll just happen more quickly, right?

   30. JRJoe Rogan1:03:02

       Yes.
10. 1:17:04 – 1:32:03

    Black holes, gravitational waves, and the scale of the universe (plus alien life debates)

    1. JRJoe Rogan1:17:04

       I was just reading some article about black holes roaming through the universe, and that some of them, some of them, they're detached from galaxies, right?

    2. BGBrian Greene1:17:11

       They can be. I mean, oftentimes people think about black holes as these gargantuan structures that form from collapsed stars. There's a big one in the center of our Milky Way galaxy, weighs four million times that of the sun. The photograph of a black hole in the galaxy M87 that got the world excited a couple of years back, 55 million light years away, billions of times the mass of the sun. But the reality is anything, if you compress it enough, becomes a black hole. If you take an orange and you squash an orange down (laughs) sufficiently small, according to Einstein, it becomes a black hole.

    3. JRJoe Rogan1:17:46

       (laughs)

    4. BGBrian Greene1:17:46

       So, these things don't have to be gargantuan. The flip side of it is, we also typically have an intuition that black holes are really dense, right? That's usually the way we think about them. But if you make something sufficiently large, regardless of how low its density is, it will also become a black hole. So, you can make a black hole out of air, by just having enough air. If you have enough air, a sufficiently large sphere of air, it would become a black hole too, with a density of air. So, all the intuitions (laughs) that we typically have about black holes, that they have to be dense and they have to be gargantuan, not right.

    5. JRJoe Rogan1:18:24

       So, black holes are just a part of the elemental structure of reality itself.

    6. BGBrian Greene1:18:30

       Yeah. When you look at Einstein's equations, right in his mathematics, there's a little formula (laughs) that you can see where it says, if you have any mass M, whatever mass you want, and you squeeze it into a radius, R, that's less than two times Newton's constant, 2G, times M, divided by C squared, speed of light squared... A formula. Details don't matter. But you take any mass, if the radius within which that mass sits is less than 2GM over C squared, it is a black hole. Period. End of story. According to Einstein. Now, Einstein left out quantum mechanics. Weirdly, right? Because his Nobel Prize was for quantum mechanics. It was for a paper he wrote in 1905 about the photoelectric effect. But he never really believed that quantum mechanics was the true description of the world. And when he was developing the general theory of relativity, he was just thinking about gravity and not quantum mechanics. Stephen Hawking came along in 1974 and started to inject quantum mechanics into our understanding of things like black holes. And that's where Hawking proved that black holes are not completely black. He showed that black holes allow a certain amount of radiation to leak out of their surface, leak out of the event horizon, or leak out from just beyond the edge of the event horizon. And so, yes, when you think about black holes, as far as we can tell, they are a fundamental quality of the world. But you have to include quantum physics to truly understand them, and that's the cutting edge of what's happening right now.

    7. JRJoe Rogan1:19:59

       So, they're a fundamental quality of the world, but they're also in the center of every galaxy?

    8. BGBrian Greene1:20:04

       It seems to be the case. The Sloan Digital Sky Survey did a wonderful study of a vast number of galaxies, and I've seen these wonderful images where they put, like, a little red circle around all those galaxies that have a black hole in their center, and there are red circles all over that imagery. So, it seems to be a ubiquitous quality, that black holes are at the center of galaxies, and those are typically gargantuan black holes, millions or billions of times the mass of the sun.

    9. JRJoe Rogan1:20:35

       Do we know why they exist at the center of a galaxy?

    10. BGBrian Greene1:20:39

        Y- y- y- uh, n- you know, there's still a lot of uncertainty about galactic formation. You know, some have suggested that early stars, which were quite large compared to more modern stars, when they exhausted their nuclear fuel and they collapsed in on each other, they created black holes that were large. And then they continued to suck in more material from the environment, and they grew larger and larger still. So, that's sort of one rough way that people think about how these massive, enormous black holes may have formed, but it's uncertain. LIGO, you know, this Laser Interferometer Gravitational Wave Observatory, gravitational waves, it- it took headlines a few years ago when it detected the first ripples in the fabric of space. It detected them from two black holes-

Episode duration: 2:42:28