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Joe Rogan Experience #1233 - Brian Cox

Professor Brian Cox is an English physicist and Professor of Particle Physics in the School of Physics and Astronomy at the University of Manchester in the UK. Tickets for Brian Cox Universal Adventures In Space & Time available at: US & CANADA: https://profbriancoxlive.com Rest of World: https://briancoxlive.co.uk

Brian CoxguestJoe Roganhost
Jan 29, 20192h 34mWatch on YouTube ↗

EVERY SPOKEN WORD

  1. 0:010:45

    Nixie-tube gadget chat and tour kick-off

    1. BC

      That's very cool.

    2. JR

      Three, two, one. Yeah, a guy named, uh... Well, it's, it's online Twitter ha- or his, uh, Instagram handle is TGTstudios. And he makes these... I actually had one made for Elon. Elon Musk loved it too, so we made him one with... He made one with, like, this very beautiful red wood.

    3. BC

      Yeah.

    4. JR

      And those are... What are those things made out of, Jamie? The... Some diodes or something?

    5. BC

      Nixie tubes is what it's called.

    6. JR

      Nixie tubes. He has to-

    7. BC

      It's like valves, right? They're old...

    8. JR

      Yes.

    9. BC

      ... valve technology.

    10. JR

      Yeah, he has to get them from Russia.

    11. BC

      Yeah.

    12. JR

      That's, uh... He has them delivered over from Russia, so they might have, like, listening devices implanted in them as well.

    13. BC

      Yeah. (laughs)

    14. JR

      So, Brian, good to see you, man.

    15. BC

      Great to be back.

    16. JR

      Yeah, great to have you back.

    17. BC

      Girl, these shoes.

  2. 0:455:17

    Cosmology as a framework for meaning: scale, galaxies, and our place

    1. JR

      So tell me about this tour that you're doing.

    2. BC

      It's a, it's a, a world tour.

    3. JR

      Try to keep this sucker like a fist from my face.

    4. BC

      Oh, yeah.

    5. JR

      There you go.

    6. BC

      How's that?

    7. JR

      Yeah, perfect.

    8. BC

      Yeah. So world tour, starts next week in, um, the UK, and then we go everywhere from the South Island in New Zealand all the way to the Arctic Circle, to Svalbard, which is north, th- the furthest north that you can go on a (laughs) commercial aircraft.

    9. JR

      Wow.

    10. BC

      In the middle, we're in the States for a month, in, uh, mainly May. And, uh, yeah, it's, it's about cosmology and about the questions that cosmology raises. So if you're interested in the science of how did the universe begin, even questions of what may have been there. Is the universe eternal? Is there such a thing as before the Big Bang? What is the future of the universe? How does complexity emerge spontaneously in a universe? I mean, we sort of take it for granted that we, we... There's a big bang, and it's all hot, and there's just this kind of hot glow of stuff. And out of that, spontaneously, in 13.8 billion years, you get something like the Earth with a civilization and life on it. So how does that... Do we know anything about that? I mean, we do. I'm asking the question rhetorically. (laughs)

    11. JR

      Right.

    12. BC

      We know quite a lot about it. So it's, it's really about showing the size and scale of the universe, but addressing those questions I think everybody has about what does it, what does it mean to be human? This tiny little finite life that we lead in a possibly infinite universe, how do you make sense of that?

    13. JR

      Well, it's incredibly exciting to me that th- there's a giant audience for this, and that wha- what Neil deGrasse Tyson had been doing and what a, a lot of public touring intellectuals are doing now, they're doing these giant theaters. And these people are coming out to see these shows, and we're realizing that there's... I mean, I hate to use the term market for this, but there's a demand for this, and there's a lot of people who are incredibly fascinated by this.

    14. BC

      Yeah.

    15. JR

      And it's, it's spreading information. It's spreading knowledge.

    16. BC

      Yeah. I mean, it's... In the UK particularly, I mean, D- Wembley Arena, for example, you know?

    17. JR

      Wow!

    18. BC

      You're talking about 10,000 people, 12,000 people-

    19. JR

      That's incredible.

    20. BC

      ... in these shows. And you're right, they are coming. Al- although, you know, they're, they're big shows, spectacular screens and all that. They're, they're coming for to think. Th- th- they're coming to hear about what we know about the universe and nature. And I think... You know, I think... I'm not surprised people are interested, because these are questions that everybody asks. You know? I mean, just why am I here? You know, everybody's sat-

    21. JR

      Yes.

    22. BC

      ... there asking that question. But I... My point is that there is a framework, there's a framework of knowledge. There are things we know about the universe. So it is true that science, scientists are not gonna tell you why you're here. (laughs) They're not gonna tell you what the meaning of life is. But there is actually a, a... There are things you need to know if you want to start to explore those questions for yourself. I mean, you need to know that there are two trillion galaxies in the observable universe. You need to know that the Milky Way galaxy has got 200 billion stars. Most of those stars now we know have planetary systems. We estimate there are t- something like 20 billion Earth-like planets, or potentially Earth-like planets, in the Milky Way galaxy alone. So if you're asking questions about, "What is my place in the universe?" you need to know those things first of all. It's a framework within which you can think.

    23. JR

      When you get to those numbers, when you're talking about trillions and billions and tho- all those zeros, my brain just goes numb. I... There's this lack of comprehension that I'm, I'm well aware of. Like, those numbers get thrown about, I go, "Oh, 200 billion."

    24. BC

      Hmm. No, every-

    25. JR

      And it just (swoosh sound) .

    26. BC

      I think everybody does. I think ev- every scientist that... No scientist can picture that number. I mean, e- even the small number, 200 billion- (laughs)

    27. JR

      The small number, right.

    28. BC

      ... the number of stars in one galaxy. And then when you say two trillion galaxies, y- you know, that, that's... I challenge anyone to be able to picture that. But it is the reality that we've observed. We've... You know, we... I mean, we haven't counted all two trillion, by the way. We have, we have a thing called the Sloan Digital Sky Survey, which maps the positions of galaxies. So you can... You know how much of the sky you've surveyed, and you know how many galaxies you've counted, and then you can spread that across the wider universe. And you get this picture of a vast and possibly infinite universe. I mean, we, we know that the universe, or very strongly suspect, that the universe is much bigger than the piece we can see. So we have good reason to think that's the case. Whether it's infinite or not is another question. And then that goes to your, you know, the, can you picture infinity?

    29. JR

      (laughs)

    30. BC

      Well, no one can picture infinity.

  3. 5:178:55

    Did the universe have a beginning? Cycles, inflation, and the multiverse idea

    1. JR

      No.

    2. BC

      There's a, there's (laughs) a weird thing as well about... You know, we, we say the universe began 13.8 billion years ago. So that's a measurement, so... Because we can measure the speed that all the galaxies are flying away from us, essentially. And then you, so you can run time backwards, if you like, to, to find out when they were all on top of each other. And so it's quite a simple measurement, and we've done that. So we say the universe began 13.8 billion years ago. But actually, all we know really was the universe was very hot and very dense at that time. And we have some theories that the universe was in existence before that, and perhaps some sort of circumstantial evidence. And that means that actually the universe could, could have always been there, eternal. And, um, when, when I talk to people sometimes, they get a bit... Some people get upset about that. Some people would rather it had a beginning. (laughs)

    3. JR

      Yeah.

    4. BC

      And the, the idea that it might have been around forever...... is more frightening somehow than the fact that it began. And that it's, it's interesting the way that people's minds work. What, what terrifies you the most, an eternal universe or a finite universe?

    5. JR

      Yeah, they're both incomprehensible. The, uh, the eternal universe, the w- if there was an eternal universe, does that negate the theory of the Big Bang, or does it mean that there's a constant cycle of Big Bangs and then expansion and then recompression or?

    6. BC

      Yeah, it could do. So those theories are, are back in vogue. Some of those theories are back in vogue again. So yes, some of them say that there's a, a cycling universe. Um, so the Big Bang is an event when space gets very hot and very dense and filled with particles, and that may happen again. Uh, some of the other theories, uh, there's a theory called eternal inflation, which is a theory that... And it's actually the most popular theory, I think, at the moment for what happened, for why the Big Bang is the way that it is. 'Cause it's got some very special features, the Big Bang, which we could talk about. But inflation is the idea that space, space-time was around before the Big Bang and it was expanding extremely fast, and it was doubling in size, in the most popular of these theories, every 10 to the minus 37 seconds, which is .000000 with 37 noughts, one of a second. So it's an unimaginably fast expansion. And then the idea is that draws to a close, so it quite naturally sort of dies away and the expansion slows down, and all the energy that was taken, that was causing that expansion sort of gets dumped into space and heats it up and makes particles, and that's what we call the Big Bang. And those theories, the slight extension to those, um, say that, that, that slowing down just happens in little patches. So most of the universe, the overwhelming majority of the universe is still inflating at that insane s- speed, and that just little patches stop, and they're Big Bangs. So you get multiple universes, a multiverse, it's called the inflationary multiverse, and we are in one of those bubbles, and that's one of the more popular theories.

    7. JR

      That's another one. I mean, that right now, I'm aware of what you're saying. I, I, I can, I can sort of visualize it in some sort of a graphic form, but it's incomprehensible. Like my-

    8. BC

      Yeah.

    9. JR

      ... my mind doesn't, it doesn't have the capacity to expand the, this sense of distance and size to that, that grasp. Is this because of just the way we evolved, we evolved here on Earth to deal with the space that's in front of us, and now over the course of, you know, in industrial civilization and education, we are now grasping these concepts that are so alien to the v- reality, the, the tangible reality that we exist in every day?

  4. 8:5512:19

    Why reality feels centered on us: Greeks, motion, and the road to relativity

    1. BC

      I'm sure that's right. Um, there, the, you know, even very simple things, like you go back to the Greeks, so Aristotle and those great, you know, very clever people, but they thought the Earth was at the center of the universe. Now, why? Because it feels like it's at the center of the universe.

    2. JR

      Right.

    3. BC

      It feels like we're not moving, um, and that's quite a deep point actually in physics. It's like, why is it that we're flying around relative to the sun very fast at whatever speed it is, 18 miles a second or something like that, and the whole solar system's going round the Milky Way galaxy and so on, but why is it that we don't feel it? And, um, the Greeks, quite naturally, said, "Well, because we're at the center of the universe." They also said everything falls towards the Earth, so therefore the Earth must be at the center. It's, it's natural.

    4. JR

      Right.

    5. BC

      And, and actually it's quite a deep, uh, thought to, to understand why it doesn't feel that we're moving. It, uh, you have to go all the way to Einstein really for someone to take that very seriously. And he, well, he said actually, he said, "Well, this..." Um, there's a great little explanation in Stephen Hawking's Brief History of Time about this, that the idea that you can't tell whether you're moving or not demolishes the notion of absolute space. So if we think about space, if I said, "Space," to you or most people I suppose, you'd think i- the way that Newton did of a big box within which things happen. And that's gotta be the, that's a natural picture of space and the universe, isn't it? It's a, a thing in which all the planets and galaxies are placed. But, um, in, in The Brief History of Time, Hawking says, "Well, imagine bouncing a ball." So we bounce a ball on the table now, a tennis ball. So I drop it and I catch it again. Um, so let's say I drop it and it takes a second to bounce up. So in that second, the Earth has moved about 18 miles or so in space around the sun. So you could ask the question, did that ball return to the same place in space or not? And the answer is, you can't answer it. You... It does from our perspective. But from the perspective of someone watching the Earth go all the way around the sun, it went up and caught it again, it had moved 18 miles.

    6. JR

      (sighs)

    7. BC

      And then from some other perspective, it would've done something else. So the point is, you can't say this is a point in space, it came back to the same place, because that just depends on your perspective. It depends on whether you're watching the sun... The Earth go around the sun or whatever it is. So, so Einstein said that means there's no such thing as absolute space.

    8. JR

      Oh.

    9. BC

      Which is, it kind of follows if you think about it, but that's a difficult... It's, it's a cool, but difficult thought process.

    10. JR

      Right. I mean, that's, that's essentially what's happening when you're on a plane. I mean, if you're throwing a ball up in the air and catching it on the plane, it's happening at a much smaller scale, right?

    11. BC

      Yeah, yeah. I mean, you're flying at, whatever, 600 miles an hour relative to the ground.

    12. JR

      Yeah. But it doesn't seem like it when you're sitting there.

    13. BC

      Yeah. And Einstein elevated that to a principle and said, "If you're moving at a bu- if you're not accelerating, you're just moving at a constant speed, uh, in a plane or now..." I mean, that's essentially what we're doing now, we're moving around the sun at effectively constant speed, "... then you can't tell." So there's no experiment you can do. We could look at the decay of a radioactive nucleus or some electricity and magnetism or bounce a ball, have a pendulum, whatever it is, and there's no experiment you can do to tell you whether you're moving or not. Therefore, that concept has no meaning because you can't measure it.And that, there, or that's led Einstein to relativity.

    14. JR

      Wow.

    15. BC

      So that, that's the, the basis of general relativity, which is our best theory of the universe.

  5. 12:1917:45

    Is space ‘flat’? Geometry, CMB evidence, and the observable horizon

    1. JR

      Now, why is it that we think that the known universe is larger than what we can observe?

    2. BC

      Well, one point is that it's, um, expanding (laughs) and, and we, we always see the same radiation out there, so the glow of the Big Bang. But there are some deeper reasons. Um, the one, uh, from the theory of inflation, the, the, uh, the, the w- the best way to explain the universe, the properties that we see, is that it's very much bigger than the piece we can see. So for example, we measure space to be what's called flat. I don't even have to tell you what's called flat, it is flat. (laughs) So if you imagine slices of space, let's imagine slices of them at different times. So, so you just slice the universe and, and say there's a big sheet. It's like this table.

    3. JR

      Okay, like a table.

    4. BC

      There's a sheet of space, and there's another sheet, another sheet. And it can, it can have a geometry, right? It can be flat, like a tabletop, or it could be curved, uh, like a sphere, or it could be curved in the opposite direction, sort of like a saddle or a bowl. And we can measure that. And when we measure it, we see it's absolutely flat. And that's a very unusual thing for it to be like. Um, it requires... Because what, what Einstein's theory says is that the, the shape of space, that the curvature of space is determined by the stuff that's in it. That's, that's basically Einstein's theory of general relativity. Put stuff in space and it curves it and bends it and warps it and stretches it and so on. And what we find is that w- there's precisely the right amount of stuff in the universe to have a completely flat universe. And the, the, the explanation, the most favorite explanation for that is the universe is way bigger than the piece we can see. And so it's like looking at a piece of the Earth, how you look at little one-mile square of the Earth, right? Then it's, it, it's flat, right? (laughs) You have to look at big distances, kind of of order the radius of the Earth, or not, you know, bigger, bigger than one kilometer anyway, or one mile, to see that actually you're on a curved surface. And that's one of the ideas about the, the universe and why it appears to be the way that it is, because it's way, way bigger. So we just, we're just looking at a little piece, and that's why it looks flat, and that's, you know, one of the ideas.

    5. JR

      Now, when you say flat, like that... My, my brain doesn't understand this because from our perspective, when you look up at the Milky Way, you see all these stars all over the place. So if you're saying flat, like what, how much height and what, what are you saying-

    6. BC

      Uh, so-

    7. JR

      ... so in terms of like the way to measure it?

    8. BC

      The, the, the best way to think about it is not to think of three dimensions as face 'cause then we can't picture it.

    9. JR

      Okay.

    10. BC

      But you can think of two, like this tabletop, and that's all right. We just forget the other one for now. And so you know what flat is on this table. I mean, you could define it. So you could say, for example, that if I draw a triangle on the top of the table, then all the angles add up to 180 degrees. So that actually defines flat. If you did that on the surface of the Earth with a big triangle, then the angles wouldn't add up to 180 degrees. Um, or you could draw a circle and say, "What's pi?" So pi is the ratio of the circumference of a circle to its diameter. That's only true on a flat surface. It's different if the surface is curved. So you can define flatness.

    11. JR

      So when you're... but when you're saying flatness, how, what is the height and what is the width? Like if you're, you've been talking about it as if it's a table, there must be some sort of a... there's a dimension to it, correct?

    12. BC

      Oh, yeah. There's a third dimension of space.

    13. JR

      Right.

    14. BC

      Uh, but the i- the same applies. It's just a generalization of geometry then. (laughs) So you, you can pi- the, the point is we can picture it in two dimensions. But you can, you can draw... Y- you can quite literally, you could imagine sending light beams out. And we do this measurement actually. We can look at the, the, the dist- the most distant light we can see, which is something called the cosmic microwave background radiation, which is... If you, if you imagine looking out... If you look at the Andromeda galaxy, which we can see with the naked eye here in LA, you can see that. It's the most distant object you can see with the naked eye, and it's about two, two million light years away or so, which means the light took two million years to get to us. So it's a long way away, but it's very big. So y- as you look further out into the universe to more and more distant galaxies, you're looking further back in time 'cause you look at something that's a billion light years away, then the light took a billion years to get to us. So you see it as it was a billion years in the past. And we can actually look so far out that we can see almost back to 13.8 billion years ago, which is very close to the Big Bang. So we can look to light that began its journey before there were galaxies, and that's the, the oldest light in the universe, which is, by the way, one of the, one of the pieces of evidence when people say, "I don't believe in the Big Bang." The answer is, "Well, you can see it." (laughs) "So, you know, it's just there." You can see it. We have pictures of it. Um, that light, it turns out that there are sort of structures or ripples in that light, um, which we can use as a ruler. So quite literally, as a, as a ruler on the sky. And then because that light's been traveling through the universe, we can see how that rule has been distorted as, as, as the light has traveled through space. And so we can infer whether space is flat or curved or how it warps, if you like, just from that measurement.

    15. JR

      Is-

    16. BC

      It's a beautiful measurement.

  6. 17:4522:06

    Beyond light: gravitational waves, LIGO, and violent cosmic collisions

    1. JR

      Is it possible that in the future we'll be able to see past 13.8 billion years?

    2. BC

      Not with light.

    3. JR

      Not with light.

    4. BC

      Because what... The, the picture is that before... It, it's actually was released 380,000 years after the Big Bang. It's a very precise number. You might say, "How do you know that?" Well, before that time, the universe was so hot that atoms couldn't form. So you had a soup of electrically charged particles. It was just too hot for electrons to go into orbit around nuclei. So the universe was opaque to light. So you just couldn't... It was like one... almost like a big glowing star, if you like.And then when it was expanding, it cooled past the point where the atoms could form. And at that point, it becomes transparent, really almost instantly in a cosmic time scale. And so the light could then travel in straight lines through the universe, and we can see that light. So we see the light from that time, but further back than that, it's opaque, so you can't see past that with light. But you can, potentially, with gravitational waves, which is this measurement that got the Nobel Prize a couple of years ago, the LIGO experiment here in the United States. And that se- looks for ripples in the fabric of space and time. And in principle, if we had a big enough detector, you could see the ripples from the Big Bang. So you could in- you could take an image of the Big Bang in gravitational waves, which would be ... But you need a enormous sort of space-based detector that we're not gonna build any time soon.

    5. JR

      Now, obviously, this is all through equipment and technology that's been invented over the last few hundred years-

    6. BC

      Mm-hmm.

    7. JR

      ... and perfected. Is it possible that things could get better, and you could get, uh, some, some ability to detect things, even in a, a far more distant way?

    8. BC

      Yeah, I mean, the, I think gravitational waves are, are incredible. I mean, Einstein predicted them in 1915. N- never thought they'd be detected-

    9. JR

      Hmm.

    10. BC

      ... because you need such a hyper ... You need lasers, for ... Didn't have lasers.

    11. JR

      Right.

    12. BC

      But the thing, LIGO, this experiment, which is half in, uh, near Seattle in Washington State and half in Louisiana, so they've got two detectors. And they're basically sort of, uh, I don't know, three-mile-long laser beams, um, that just sit and measure the sort of stretching and squashing of space as the ripples in the fabric of the universe go through. And, and what they've been observing, uh, collisions of black holes. So you can imagine-

    13. JR

      Wow.

    14. BC

      ... how extreme ... Like, a colliding black holes is an incredibly extreme event, so it shakes the fabric of the universe, and the ripples come across the universe. And these laser beams, which are just basically rulers, can detect it. They just sort of ring almost, like, you know, just vibrate as the ripples go through, in space and time. Kip Thorne, who got the Nobel Prize, uh, last year for this, he's one of the greatest living physicists, hi- I once heard him describe it as a storm in time. So you've got this, a time storm. It's a beautiful image. (laughs) But-

    15. JR

      Oh, God.

    16. BC

      So that technology's incredible, 'cause it, it, the change in length, is I can't remember the exact number, but it's way, way, way less than the diameter of an atomic nucleus, so the change in, in length of the beams. It's tiny measurement, but we can do it.

    17. JR

      So this ti- a collision of black holes, the idea that you can detect that-

    18. BC

      Yeah.

    19. JR

      ... that ...

    20. BC

      Yeah. They, the, the, there were ... I s- the paper, the first paper they published, there are two black holes, and they were about 30 times the mass of the sun each, and they were orbiting each other and spiraling in towards each other. And, uh, they accelerated. At one point, they were approaching each other at one-third the speed of light, and they accelerated to two-thirds the speed of light in a tenth of a second and then hit each other. And the explosion, the energy release, was ... I think I'm right, it was something like 50 times the energy release that the power of all the stars in the observable universe glowing, and it was something like 50 times that amount of energy for a tiny fraction of a second.

    21. JR

      Whew.

    22. BC

      But it's, it's an unimaginably violent event, and that's why our detectors can see the ripples that that makes in space and time. And we detected, God, maybe it's two or three of them now, and, and also, uh, two neutron stars colliding, we saw that as well with it. So it's an incredible m- machine, which is why it got the Nobel Prize.

  7. 22:0626:36

    Black holes, event horizons, and what stars become when they die

    1. JR

      Now, there's a super massive black hole at the center of every galaxy.

    2. BC

      Yeah, yeah, we think.

    3. JR

      But there's also other black holes that aren't necessarily in the center of galaxies?

    4. BC

      Yeah, so these little ones, well, little, you know (laughs) -

    5. JR

      Little. (laughs)

    6. BC

      Um, they, they're, they're a few times the mass of the sun, and they're from collapsed stars. So they are stars at the end of their life, very, n- bigger than the sun, more massive than the sun, but they run out of their fuel, and they start to collapse because gravity squashes them. And if they're sufficiently massive, then there's nothing that can stop the collapse, and so they collapse, as far as we know, to a point, right, uh, uh, essentially an infinitely dense point. We don't really know what happens at the ... W- we don't know what happens right in the middle. But they collapse to such an extent that there's a region around it where, from which light can't escape, and that's, uh ... So nothing can escape, and that, that's a black hole.

    7. JR

      And what happens to them? Do they travel? Are they moving through space?

    8. BC

      Yeah, they, they're, they're, they're still stars.

    9. JR

      Right.

    10. BC

      Uh, you know, so they're, they're still there. Um, they, they're surrounded, this region, where if you fall in, it's called the event horizon, and if you go across that horizon, then you are going to the center. There's one way of thinking about it, which is quite cool, which is that, uh, the time and space sort of flip, is one way to think about it. So in the same way that we are going into the future now, so, so we're going to tomorrow, there's nothing we can do about it, we are going to tomorrow, um, in the same way, if you fall in across the event horizon of a black hole, you are going to the middle, the singularity, it's called. So that's, that's your future. Every, every line of your future points to the center of the black hole, so it's kind of the ultimate (laughs) o- no escape, the ultimate prison. You're gonna get squashed to an infinitely dense point, basically.

    11. JR

      So n- but not every star becomes a black hole at the end of its life?

    12. BC

      No, uh, 'cause if, if, um, something like the sun, um, then-

    13. JR

      We have a small star.

    14. BC

      It's quite small, yeah. And, and when it collapses, there's a, there's a, uh, a sort of a pressure, a force, if you like, which is caused by the fact that electrons don't like to be very close to each other.So it's called a Pauli exclusion principle. But essentially what happens is that ... So as they get squashed closer and closer together, they move faster and faster to sort of get out of each other's way, if you like, and that makes a force which holds them up. And so that creates what's called a white dwarf star. So, so you can have a blob of matter. They're about the size of the Earth, but they're about the mass of the sun. And, uh, so that's, that's for smaller stars. They end up as these white dwarf things which are very dense objects. There's another version which is called a neutron star which is the same thing, but for neutrons. And they, they move faster and faster, so the ... If it's, if it's massive enough that it overwhelms the electron thing, then the electrons sort of fu- ... Crush into protons and turn into neutrons, and the whole things starts again. And so a neutron star can be, you know, at lea- ... One and a half times the mass of the sun, let's say, but it can be, uh, about, what, 10 miles across. (laughs) So-

    15. JR

      Wow.

    16. BC

      So that's an incredibly dense ball of matter held up by this n- ... The neutrons moving around. It's got a fancy name, it's called neutron degeneracy pressure, but that's what it is. (laughs) But if you go even bigger then even that can't hold it up. And as far as we know then, there's no known force that we know of that can hold, hold the thing up if it's m- ... If it's too massive.

    17. JR

      S-

    18. BC

      And so that's when it just w- ... Almost winks out of existence, if you like. I ... It collapses and collapses and collapses, um, and that's when you get a black hole.

    19. JR

      We try to put that into perspective, the eart- ... The sun is a million times bigger than the Earth.

    20. BC

      Yeah.

    21. JR

      And this, this neutron star is, wha- ... What'd you say, one and a half times the mass of the sun-

    22. BC

      Yes, but they, they-

    23. JR

      ... but 10 miles wide?

    24. BC

      Yeah, yeah. So ... And there's loads of those around. They're, they're called pulsars.

    25. JR

      (laughs)

    26. BC

      So we, we, we see those all over the place. The, the first one that was discovered was called LGM-1 because they spin very fast and, um, th- ... It was called LGM-1 'cause it's a very regular pulse and they thought it was little green men.

    27. JR

      Oh, wow.

    28. BC

      So they called it, kind of jokingly, Little Green Men 1.

    29. JR

      (laughs)

    30. BC

      And, um, so, yeah, there ... We, we've seen the ... There's one called the Crab Pulsar which is in the Crab Nebula which we saw the supernova explosion. So that's when a ... When one of these stars explodes at the end of its life and then collapses to form a neutron star. And we saw that in 1054 AD.

  8. 26:3630:45

    Our solar system’s neighborhood mysteries and practical interstellar concepts

    1. JR

      We- ... Wasn't there some speculation that our gal- ... Or our solar system at one point was ... Had a ... Was a binary star system and that one of those stars had become a dwarf?

    2. BC

      I don't know. Um, I haven't heard that.

    3. JR

      Some- ... Someone ... I'd read something about that in relationship to the dense object they believe is outside the Kuiper Belt.

    4. BC

      Yeah, I mean, there's some evident- ... There's a bit of evidence that there's something out there, yeah.

    5. JR

      Yeah.

    6. BC

      Um, cou- ... Because of the periodic extinctions and things on Earth, like, you get periodic bombardments from out in the Kuiper Belt, so yeah, I think one of the theories is that-

    7. JR

      Periodic extinctions?

    8. BC

      Well, yeah, so if we're talking about like the ... You know, there, there've been ... There have been mass extinctions on Earth when, when a lot of the life died and, um, we don't know what caused all those, but, um, sometimes they're impacts from space. That seems clear. And so yeah, there are theories that there's something orbiting out there which can disrupt all these objects out in the Kuiper Belt that sends loads of comets and, you know, asteroids inwards to the inner solar system-

    9. JR

      Ah.

    10. BC

      ... and it can cause, uh, havoc. And so the- ... There's some people look at those theories. I mean, I don't know. It's one of those i- it is a possibility that there's something out there.

    11. JR

      Right because the speculation-

    12. BC

      So-

    13. JR

      ... was that there's something out there's ... Correct me if I'm wrong, something called the galactic shelf, like, that it gets to a certain space and it indicates that there's something far larger out there.

    14. BC

      Uh, yeah. I mean, I think ... I don't know the exact- ... About the stellar-sized or mass objects-

    15. JR

      Mm-hmm.

    16. BC

      ... out there. I don't know that. I mean, there are some, uh, sort of suggestions there's another planet out there, a big planet, for example. But you're, you're right, there can be, there can be stuff orbiting way beyond the Kuiper Belt. And we're talking, you know, a light year away or something like that now. Um-

    17. JR

      It's, it's interesting because it's incomprehensible the distance, right, in, in our minds, how far that must be out past what we used to call Pluto, but for whatever reason, that becomes more interesting 'cause it's in our neighborhood-

    18. BC

      Yeah. (laughs)

    19. JR

      ... whereas if they find some distant star system and ... That it might have a planet that's similar to Earth, that doesn't seem as, uh, compelling for whatever weird reason.

    20. BC

      No- ... Yeah, I mean, I, I think the, the planets around Alpha Centauri and Proxima Centauri which are the closest stars, it seems like there are planets around those now. And i- ... That, that was interesting because we could conceive of going there.

    21. JR

      Right.

    22. BC

      And there was this idea ... Yeah, Stephen Hawking actually and some others, uh, before he died had this idea called Breakthrough Starshot which is the idea to send a little probe, uh, out to, uh, the center- ... The Alpha Centauri system and it, and it ... I think in their view, Y- Yuri Milner as well, the, the ... You know, the, the entrepreneur wanting to do that, and, uh, there ... It's ... I think it's, uh, something like 100 years travel time or something with, with the ... with our current technology. And they've pointed out that, you know, we don't do that now. We don't think 100 years in the future, but if you go back when people were building cathedrals people used to routinely start projects that would take 100 years to bear fruit.

    23. JR

      Yeah.

    24. BC

      And so we could imagine going there and that's ... That then becomes fascinating, I think, 'cause then you've got a solar system, another solar system, that you could go and visit conceivably.

    25. JR

      Conceivably. Yeah, I mean, what kind of speed are we talking and how long would it take to get there?

    26. BC

      Well, yeah, I mean, so it is ... I think the, the idea was about 100 years to get there.

    27. JR

      Oh.

    28. BC

      So it's going, you know, four light years or so in 100 years, so whatever that in terms of-

    29. JR

      So you would have to essentially do what they did in, like, the Ridley Scott Alien film and put people into some sort of a hyper sleep-

    30. BC

      Oh, yeah, a robot probably. It wou- ... It wouldn't be a crew. It prob-

  9. 30:4537:31

    Mars reality check: habitability, radiation, gravity, and why it’s still the target

    1. JR

      I'm, uh, uh, of the opinion as time goes on and augmented and virtual reality gets better and better that, uh, it doesn't really totally make sense, unless we're talking about colonizing some place, to send biological life to another planet. And if we can send some probe that doesn't have to worry about the, you know, the biology being affected by radiation or by the speed of travel or even-

    2. BC

      Mm-hmm.

    3. JR

      ... by food, we can send something out there and almost be there by v- virtue of, you know, f- goggles, virtual reality goggles-

    4. BC

      Mm-hmm.

    5. JR

      ... or, or something else.

    6. BC

      Yeah. Uh, you hear that in science, uh, at the moment, space science, we have this debate a lot actually because, of course, um, space probes like Curiosity that's on Mars at the moment, that's really cheap, uh, compared to sending people to Mars. And so quite often the scientists who want to find out about the worlds will say, "Well, we should spend it on robots. We shouldn't spend it on people." I think crewed space exploration is in s- in some ways, I mean, it's clearly true at the moment that humans can do more than robots, so we can explore the place better.

    7. JR

      For now.

    8. BC

      Yeah. But, but I think it has to be... It's about something else. I mean, it's about... It... And it's not only... It, it's about living and working off the planet, which I think is quite a persuasive argument actually. We've, we've already industrialized near Earth orbit, so it's already a multi-billion-

    9. JR

      Mm-hmm.

    10. BC

      ... dollar industry, you know, with communication, satellites, and weather satellites, GPS, whatever, yet we're already up there. And so learning to live and work in space is, I think, a natural extension of our, of our civilization. Plus the fact if you talk to Elon or Jeff Bezos, they point out that the, the amount of resources available just slightly above our heads is vast. And so I, I remember I talked to Jeff Bezos actually once, and he, he thinks really simply, and he said, you know, "For example, in the asteroid belt, there's enough metal, I think, to, to build a skyscraper s- what is it? Eight- uh, something like 800 stories tall and cover the Earth in it, right? (laughs) If you want." Now, we don't wanna do that, but his point was that, that the energy from the sun is all up there, the resources are up there, so you could almost imagine trying to zone the Earth residential at some point in the future to protect the planet and do your heavy industry off the planet, for example. And th- these sound, it sounds like science fiction, except that now SpaceX and Blue Origin, those people have got reusable rockets. So suddenly, the economics become sensible. So I think it... I think, I think expansion is good, and I think we will expand, and I think we will expand outwards because there's not much room left on this planet to expand, so I think we'll do... So it... But it's a... That's a whole different idea. It's, it's not about gathering scientific information. It's about a frontier an- and all the benefits that come from operating as a civilization on a frontier, which we've, have lost on the Earth because there is no frontier left. And so I like that idea.

    11. JR

      Mm-hmm.

    12. BC

      That Mars... And w- when you talk about Mars, especially with Elon, he's right that that's the only place you can go. So there, there is no other planet we can go to other than Mars. Uh, you can't go to Jupiter or Saturn.

    13. JR

      Right.

    14. BC

      You can't go to Mercury or Venus. So if we wanna go somewhere and expand our civilization, it has to be Mars, and everything's there that you need. So, but that, that's a different thing saying that you wanna find out stuff. You're right, if we just wanna find out stuff, then you send robots.

    15. JR

      But as far as expanding actual civilization and bringing it to another place, one of the things that freaks me out is people get depressed about living in Seattle.

    16. BC

      (laughs)

    17. JR

      Total... I mean, you, you're gonna live on Mars? I wouldn't.

    18. BC

      I, I agree with you.

    19. JR

      I wouldn't. Yeah.

    20. BC

      It's... Uh, it'd be a hor- horrendous thing. It's, it's like the... A bit like the Western Front. Yeah, it's the frontier when people cross the states.

    21. JR

      Yeah.

    22. BC

      An incredibly dangerous thing to do, but it's far-

    23. JR

      But when people crossed the states, they still got to Wyoming and beautiful places and Colorado and...

    24. BC

      Yeah, but it was hard.

    25. JR

      Yes.

    26. BC

      I wouldn't have wanted to do it.

    27. JR

      But once you got there, there's a river and there's trout in the river and the, the meadows are green and...

    28. BC

      It's, it's right... I mean, (laughs) I, I agree with you, right? I mean, the... I'm not gonna go there 'til there are vineyards and-

    29. JR

      Yes.

    30. BC

      ... hotels and things, but however (laughs) , uh, it is true that there are people who like the challenge. And what is true about Mars, it's interesting actually, 'cause w- we know something about the history of Mars now, quite a lot about the history of Mars, and it's certainly clear that there was water, almost certainly oceans and rivers. So... And that water is almost certainly still there. So I would say certainly still there.

  10. 37:3147:58

    Science fiction vs physics: Sunshine, Star Wars, and why realism often looks wrong

    1. JR

      Do you watch those movies-

    2. BC

      (laughs)

    3. JR

      ... and shake your head?

    4. BC

      I quite... I like them. I just-

    5. JR

      Do you?

    6. BC

      I, I like science fiction, you know?

    7. JR

      Right.

    8. BC

      I, you know, so, yeah, I don't sit there... I, I grew up with Star Wars. That was my... When I was nine years old or something like that. So I don't sit there going-

    9. JR

      It's funny watching it now.

    10. BC

      I just don't... Yeah, I'm not having this.

    11. JR

      (laughs)

    12. BC

      I did, I had a, an argument with Neil deGrasse Tyson... Not an argument, but a debate with him about lightsabers once. 'Cause I claim that they're physically po-... That in principle, they're possible. Um, and he was trying to say that they aren't, but they are.

    13. JR

      Would it have to loop back around 'cause the light's not continuing to-

    14. BC

      It-

    15. JR

      Like, the fact that it goes to a certain distance and pauses?

    16. BC

      Well, you'd have to have a mirror or something, I guess, yeah.

    17. JR

      Something would have to-

    18. BC

      That's true.

    19. JR

      ... be the end of it, right?

    20. BC

      That's true. So it wouldn't... It, it would be a different kind of lightsaber. The, the only point I was making is that photons, particles of light, can bounce off each other.

    21. JR

      Hmm.

    22. BC

      So we see that in really high-energy experiments in particle accelerators, we can collide photons together. So my point was a bit of a pedantic physicist one, but it is... 'Cause it, it is true that light can bounce off. It can hit light-

    23. JR

      Right.

    24. BC

      ... but very, very high energy.

    25. JR

      But when they press that button, it goes to a certain distance.

    26. BC

      Yeah, yes, yeah. I wasn't... That's engineering.

    27. JR

      Right.

    28. BC

      (laughs) No, I agree with you. I agree with you. The distance thing doesn't work.

    29. JR

      Well, there's also-

    30. BC

      Yeah, I agree. (laughs)

  11. 47:5855:44

    Warp drives and wormholes: what GR allows vs what nature likely forbids

    1. JR

      I always wanted to ask about their, their concept of propulsion, that you, uh, that almost like space would be flat and you would fold space over and you would intersect those two points and you would be able to travel vast distances-

    2. BC

      Mm-hmm.

    3. JR

      ... instantaneously, right? And I'm doing a terrible job of explaining it, I'm sure. But is that a, a concept that people have actually considered?

    4. BC

      Yeah, you can... In, in general relativity... So, so Einstein's... I should say what it is. Uh, Einstein's theory of general relativity is our best theory of space and time. And so it really is... As we've talked about before, it's you imagine space and time as a sheet. Just imagine it as a thing, sort of a, a literally a sheet surface. And all the theory says is that if you put matter and/or energy into that, then it curves it and distorts it and it can stretch it and make it shrink.And so it's the response of space and time to matter and energy. So if you, if you... The- the simplest version would be the- the sun. So you put the- a big spherical ball of stuff in there, and it- it warps space and time such that the nice straight lines, something just traveling, minding its own business through that warped space, turns into an orbit.

    5. JR

      And that's why you can actually-

    6. BC

      And that-

    7. JR

      ... kind of see things that are behind the sun?

    8. BC

      Yeah.

    9. JR

      Okay.

    10. BC

      So light bends around the sun-

    11. JR

      Okay.

    12. BC

      ... um, because it's just traveling through the curved space. The Earth goes round the sun because it's just rolling, minding its own business through the curved space. So, um, an example would be, you might say, "Well, how does curved space, how- how does, can that give rise to something that looks like a force, which is gravity?" So the best analogy I know of is to think of walking around on the surface of the Earth. So if you stand on the equator of the Earth, and you- you, with your friend, and you- you say, "We're gonna walk due north, so we're gonna set off..." Let's say we're 1,000 miles apart on the equator and we're gonna walk due north. What's gonna happen? So you walk in straight lines. You don't change direction, you don't do any accelerating. But the straight lines are the lines of longitude on the surface of the Earth. So as you go further and further north, you get closer and closer together. And if you carry on to the pole, you bump into each other.

    13. JR

      Hmm.

    14. BC

      But nothing's happened, right? No one's... no one... there's no forces acting. It's just that you're moving on a curved surface, and so you get closer. And that's basically Einstein's theory of general relativity. Now, why did I start talking about that?

    15. JR

      Event horizon, the idea of, uh, folding.

    16. BC

      Oh, yeah. So- so you can... So all you have to do so that there's folded kind of geometries, is you have to try and specify how, where you would put the matter and what kind of stuff you'd put there to make the geometry fold in that way. And you can do, you can do it. So you can, you can write down that geometry. So it's called a- a warp drive geometry, I think it's called. It's in textbooks. So you can do that to- to have a warp drive. The question becomes, what sort of stuff would you have to actually put into the real universe to make it warp in that way? And, um, it- it always, it usually turns out that it's the kind of stuff that doesn't exist.

    17. JR

      Right. (laughs)

    18. BC

      (laughs) But it has properties. It's ma-

    19. JR

      Right.

    20. BC

      ... sort of matter or sort of energy that has properties that do not exist in nature as far as we can tell. But you can still write the geometry down in Einstein's theory. So if you have the stuff-

    21. JR

      So if you had a significant force or mass or whatever it is, if you had that-

    22. BC

      Yeah.

    23. JR

      ... stuff that doesn't exist, it is a concept that- that- that could be implemented.

    24. BC

      Yeah. So the geometry exists. So-

    25. JR

      Right.

    26. BC

      So you can, you can, you can do it and you can do the calculations and you can see the warp drive. You can construct wormholes that connect distant regions of the universe, which you could use as time machines. Um, you can do all that in the theory. But in nature, you'd have to have the right stuff to do it.

    27. JR

      But that stuff is not real-

    28. BC

      That seems to be the case.

    29. JR

      ... as far as we know.

    30. BC

      Yeah.

  12. 55:441:09:44

    Life in the universe: microbes likely, complex life rare, and the ‘slime to giraffes’ problem

    1. JR

      What are your thoughts on, on alien life, on life outside of this planet?

    2. BC

      I-

    3. JR

      Is that something you think about?

    4. BC

      Yeah. I, I think there must be, um, even in the solar system, I would not be surprised if we find microbes on Mars or on some of the moons of Jupiter or Saturn, where there's liquid water.

    5. JR

      Like Europa?

    6. BC

      Yeah. And the reason is, if you think about... The reason I think that, and it's a guess, is because if you look at the history of life on Earth, then... So Earth formed and it was just a, a... There was no life, it was a ball of rock. And almost as soon as it cooled down, we see evidence of life. So certainly 3.8 billion years ago, possibly even further back than that, we see evidence of life on Earth. So somewhere along the line, geochemistry, active geochemistry, became biochemistry on Earth. And we have some idea, you know, that, that if you get s-, uh, gradients of temperature and acid and alkaline and the conditions that are naturally present on the surface of oceans, then complex carbon chemistry spontaneously happens. So we have a... We know that life... Almost certainly we know that life began on Earth. I mean, the oth- the other option is it came from space or something like that, but it probably didn't (laughs) , right? It probably began on Earth. Um, so that means that, at least here, that happened, and that we know that the conditions that led to the origin of life on Earth were present on Mars 3.8-4 billion years ago, and we know that they're present on Europa today. So I don't see that there's anything special. Life is just chemistry, and it... Uh, and the, the idea that geochemistry becomes biochemistry is not fanciful because it happened here. So I think that given the same conditions, it would be surprising to me if the same thing didn't happen, in that life begins. So I, I... That's one of the... To test that is one of the great frontiers of science now. It's one of the great challenges, which is why w- another reason we're interested in Mars, because we know those conditions were there. We know there were what's called hydrothermal vent systems on the floors of oceans on Mars 3.8 or 4 billion years ago, so it would be good to know if what I've said is right. And the, the way we find out is to find life or evidence of past life.

    7. JR

      Uh, d- are you aware of, uh, the speculation that was going around? Wh- how, how recent was it, that octopi thing, the oc-, uh, uh, the oc- octopus eggs? They, there was a group of scientists that were speculating that it's pos- you know, panspermia, the idea of panspermia?

    8. BC

      Yeah, yeah.

    9. JR

      That it's possible that octopi had come from somewhere else, some frozen eggs had actually come from somewhere else and, and landed on Earth. And these were, like, legitimate scientists who were contemplating, not morons.

    10. BC

      I, I don't think-

    11. JR

      You've seen this?

    12. BC

      The... No, I didn't, but I mean, it, I think it's unlikely. So panspermia doesn't have to be unlikely.

    13. JR

      Right. Sure.

    14. BC

      I mean, for example, you might have seen the other day we found an Earth rock on the moon.

    15. JR

      Yes.

    16. BC

      Right. Well, the, well, it's back on Earth now-

    17. JR

      Yeah. Right.

    18. BC

      ... 'cause the Apollo astronauts brought it back, didn't they? And it's 4 billion years old or something like that.

    19. JR

      One of the oldest rocks ever found.

    20. BC

      Yeah.

    21. JR

      Right.

    22. BC

      So, so we know that material gets transferred between planets. Um, and so it's not inconceivable that microbes could survive that journey, right? We know that microbes can survive in space, for example. So that isn't mad. Uh-

    23. JR

      Right.

    24. BC

      ... it's, it's probably unlikely, but it's not mad. But with the octopus, I hadn't heard that. But the thing is that the octopus is still extremely similar biologically to us. I mean, the differences are negligible.

    25. JR

      Yeah.

    26. BC

      So it's still got the same energy system with single ATP and DNA and all that stuff. It's all very, very similar.

    27. JR

      It was something about RNA and DNA. Did you, did you find that article?

    28. NA

      Yeah. I'm trying to f- I'm looking at a different one from a different website.

    29. JR

      Sorry.

    30. NA

      It's about the same thing. It has-

  13. 1:09:441:17:25

    Civilizations, the Fermi paradox, and meaning as a local phenomenon

    1. JR

      Right. Do you think that it's possible, do you ever entertain the idea that it's possible that we are the only intelligent life in the known universe?

    2. BC

      I, I-

    3. JR

      Like, this intelligent.

    4. BC

      ... I, I tend to re- I tend to restrict myself to the galaxy.

    5. JR

      Right.

    6. BC

      So I do-

    7. JR

      Hm.

    8. BC

      ... think it's possible that, at the moment, there's one civilization in the Milky Way-

    9. JR

      Wow.

    10. BC

      ... and that's us. And I think that's important, actually. And it goes back to what I was saying at the start about the, uh, astronomy and cosmology being part of the framework within which you have to think if you're looking for meaning or you're looking for how we should behave even, politically. You know, the, that has a bearing to me. I mean, imagine that we're the only place where there is intelligence in this galaxy, and how should we behave?

    11. JR

      Right.

    12. BC

      Should we actually, notwithstanding the fact that we're tiny and fragile things and insignificant physically, should we consider ourselves extremely valuable in that respect? Because there's nowhere else where, uh, you know, there, there, I would go as far as to say there would be nowhere else where meaning exists in the Milky Way.

    13. JR

      Meaning.

    14. BC

      Because meaning, it's one of those things that scientists don't talk about very much. Although Richard Feynman, one of my great heroes, did talk about it. There's a quote where he says, "What is the meaning of it all?" It's a great essay called The Value of Science. And so, what is self-evidently true is that meaning exists here because it means something to us. So that's kind of a- an obvious statement, you know. Life means something to you and me, and so meaning exists. But I think it is a local and temporary phenomenon. I think it's, it emerges. Meaning emerges from configurations of atoms, which is what we are. We are simply that. We're nothing more than that. We're very, very rare configurations of atoms, I think. And so that means that we are, if you go all the way down that line of logic, we are the only island of meaning in the galaxy, I would say.

    15. JR

      But meaning only to ourselves.

    16. BC

      Yeah.

    17. JR

      It means something to us-

    18. BC

      Yeah.

    19. JR

      ... because we're the only ones who can grasp the concept, and we are finite. We are a finite organism. We have this temporary existence while we're here. And to us, there is meaning.

    20. BC

      Yeah. And that's, I don't know any other way to define it.

    21. JR

      Right.

    22. BC

      So I'll define it like that.

    23. JR

      Yes.

    24. BC

      I don't think there's globe- you know. Otherwise, you have to believe there's some kinda global meaning, and that's a God-type thing.

    25. JR

      Mm-hmm.

    26. BC

      And I don't think that's ... I think it's more wonderful and, and more challenging to us 'cause we have to take responsibility for it to say, "We should operate such that we are it in this galaxy."

    27. JR

      Mm-hmm.

    28. BC

      There's nothing else. I'm sure, uh, I'm just a f- I'm sure there are other civilizations out there in the universe 'cause there are two trillion galaxies, like, I just can't believe this hasn't happened in other places. The question is, how often does it happen and how widely spaced are the civilizations? And I think they're very widely spaced, and I think there may be one or two per galaxy on the average. I could ... But that, as you said, uh, th- w- what, you said it beautifully, that wha- what else can we think?

    29. JR

      Right.

    30. BC

      And what, and what else do you want? I mean, I think what it says is you have to take responsibility for all those things, those spiritual things that you think about and the emotional things you think about. It, y- you, you are, you are responsible for that. You, you are that, right? (laughs) That, whatever that is, it exists in you, and it will only exist for a short amount of time. And so-... what, you know, make the best of it, would be my view.

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