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What is quantum relativity? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Katie, are you a fan of Italian food?
• 0:11
  Speaker 2: Well? I live in Italy, so here we just call
• 0:13
  Speaker 2: it food.
• 0:14
  Speaker 1: But yeah, all right, Well what about Italian American food?
• 0:19
  Speaker 1: You know, the version made by Italian immigrants to America.
• 0:23
  Speaker 2: Yeah, no, I like it.
• 0:24
  Speaker 3: It's more meatballs and more garlic, but that's still really good.
• 0:28
  Speaker 1: Well what about the opposite, what about American Italian food?
• 0:32
  Speaker 3: So is that cuisine made by American immigrants who are
• 0:37
  Speaker 3: in Italy?
• 0:38
  Speaker 2: Yeah?
• 0:38
  Speaker 1: Basically you.
• 0:40
  Speaker 3: Well, I mean I mostly just have coffee and toast,
• 0:44
  Speaker 3: which would be a really short cookbook.
• 0:48
  Speaker 1: Maybe you should try innovating. Have you ever tried putting
• 0:50
  Speaker 1: a meatball in your coffee?
• 0:51
  Speaker 2: I know I have not tried to do that, Daniel.
• 0:55
  Speaker 1: Could be a cultural revolution.
• 0:57
  Speaker 3: Well, it would indeed be revolting.
• 1:15
  Speaker 2: Hi.
• 1:16
  Speaker 1: I'm Daniel. I'm a particle physicist and a professor at
• 1:19
  Speaker 1: uc Ervine, and I don't like anything in my coffee,
• 1:22
  Speaker 1: definitely not meatballs.
• 1:23
  Speaker 2: Hi. I am Katie.
• 1:25
  Speaker 3: I host a podcast called Creature feature on evolutionary biology,
• 1:30
  Speaker 3: and I like a huge amount of sugar in my coffee.
• 1:34
  Speaker 3: So we could see how that is with meatballs as well. Well.
• 1:40
  Speaker 1: That makes me wonder since you're a biologist, tell me
• 1:43
  Speaker 1: who are the natural consumers of coffee? Like, who out
• 1:46
  Speaker 1: there in the animal world is eating coffee beans off
• 1:49
  Speaker 1: the tree.
• 1:49
  Speaker 3: That's the thing is that coffee caffeine in coffee plants
• 1:54
  Speaker 3: is meant to be slightly toxic to insects that want
• 2:00
  Speaker 3: to eat it. And it's the same story for spicy foods.
• 2:04
  Speaker 3: It's actually defense mechanism, and so the insects that will
• 2:08
  Speaker 3: try to eat these plants will not farewell. But when
• 2:13
  Speaker 3: we have it, it's actually delicious and good. Now, there
• 2:16
  Speaker 3: are palm civets who will eat types of coffee plants.
• 2:21
  Speaker 3: They eat the berries, and there's actually a coffee drink
• 2:26
  Speaker 3: made out of the beans collected from the palm civet hoop.
• 2:32
  Speaker 2: And it's very expensive.
• 2:34
  Speaker 3: Wow.
• 2:35
  Speaker 1: I don't know what blows my mind more there the
• 2:37
  Speaker 1: fact that we are sipping insect poison, or the fact
• 2:40
  Speaker 1: that that whole strategy has backfired on the coffee tree
• 2:43
  Speaker 1: because it attracts us, or how quickly a biologist will
• 2:46
  Speaker 1: turn the conversation towards poop.
• 2:50
  Speaker 2: The latter is the least surprising.
• 2:54
  Speaker 1: That is, in the end, where we overlap the darkest
• 2:56
  Speaker 1: matters in the Universe and Welcome the podcast Daniel and
• 3:01
  Speaker 1: Jorge Explain the Universe the production of iHeartRadio, in which
• 3:05
  Speaker 1: we try to do just that. Explore everything that's out
• 3:08
  Speaker 1: there in the universe, ask our deepest, darkest questions about
• 3:12
  Speaker 1: who is sipping which bits of the universe and why
• 3:15
  Speaker 1: they exist in that way? What are the tiniest particles
• 3:18
  Speaker 1: that everything is made out of, What are the rules
• 3:20
  Speaker 1: by which they play? How do they come together to
• 3:23
  Speaker 1: make civets and cats and poops and coffee and biologists
• 3:26
  Speaker 1: who wonder about all those things combined? Is it possible
• 3:29
  Speaker 1: to understand and explain the universe? We're going to try.
• 3:33
  Speaker 3: That is the first thing I think of when I
• 3:34
  Speaker 3: think about civt kat poop is the tiniest of particles
• 3:40
  Speaker 3: that make up that coffee. But yeah, I mean, I guess,
• 3:44
  Speaker 3: I guess when you can go down really really tiny,
• 3:49
  Speaker 3: and that makes things like poop less gross because now
• 3:52
  Speaker 3: you're just on the atomic level and these are just atoms.
• 3:56
  Speaker 2: They don't smell. Atoms don't smell bad.
• 3:58
  Speaker 1: I don't think, well, does it make poop less gross
• 4:02
  Speaker 1: to think that it's made of the same basic building
• 4:04
  Speaker 1: blocks as everything else, or does it make everything else
• 4:06
  Speaker 1: more gross to know that ice cream and lava and
• 4:10
  Speaker 1: kittens are made out of the same stuff as poop.
• 4:14
  Speaker 2: Interesting question, ice cream, lava.
• 4:20
  Speaker 1: Let's put a pin in that. But let's dive deep
• 4:22
  Speaker 1: into what the universe is made out of. One of
• 4:25
  Speaker 1: our deepest questions in physics, and a question that humans
• 4:28
  Speaker 1: have been asking basically since humans have been asking questions,
• 4:32
  Speaker 1: is how do things work at the smallest scale? Is
• 4:35
  Speaker 1: it possible to zoom down on what's around us and
• 4:38
  Speaker 1: explain things in simpler and simpler terms, Because you know,
• 4:42
  Speaker 1: you start out with a huge number of things out
• 4:44
  Speaker 1: there in the universe blueberries and cats and ice cream
• 4:47
  Speaker 1: and coffee and biologists and physicists and everything in between.
• 4:51
  Speaker 1: It's an incredible variety. But when you dig down a
• 4:54
  Speaker 1: little bit, you discover, oh, everything out there is made
• 4:56
  Speaker 1: out of about one hundred basic building blocks the elements
• 5:00
  Speaker 1: periodic table. Combined in different ways, you can make essentially everything.
• 5:04
  Speaker 1: And even that set of one hundred building blocks is
• 5:07
  Speaker 1: made out of an even smaller set of stuff. Right,
• 5:10
  Speaker 1: Protons and neutrons and electrons make up all of those atoms,
• 5:15
  Speaker 1: which means that the same stuff can be used to
• 5:17
  Speaker 1: make lava or kittens, or ice cream or poops, or
• 5:20
  Speaker 1: biologists or stars. All that stuff is made out of
• 5:24
  Speaker 1: the same thing.
• 5:26
  Speaker 3: It's interesting because I do know that one of the
• 5:29
  Speaker 3: things that unites kittens and lava and poop is that
• 5:33
  Speaker 3: it all obeys the laws of physics. If you throw
• 5:38
  Speaker 3: a kitten in some lava, you're going to have a
• 5:41
  Speaker 3: predictable result because of the laws of physics. Both the
• 5:44
  Speaker 3: kitten and the lava are constrained by the laws of physics.
• 5:49
  Speaker 3: But the thing that's interesting to me, and that hurts
• 5:52
  Speaker 3: my brain a little bit, is that when you look
• 5:55
  Speaker 3: at say like a very tiny quantum part of it
• 6:00
  Speaker 3: does not necessarily obey the same laws of physics as
• 6:03
  Speaker 3: say a marble. So you know, I think of like
• 6:06
  Speaker 3: a marble bonking into another marble. I can somewhat understand
• 6:11
  Speaker 3: how that works. But then you go down small enough
• 6:14
  Speaker 3: and it's not just tiny atomic marbles bonking into each other.
• 6:18
  Speaker 3: Weird stuff happens that blows my mind.
• 6:21
  Speaker 1: It is incredible that the laws of physics seem to
• 6:24
  Speaker 1: be different at different scales, like at different distances or
• 6:27
  Speaker 1: different energies. It seems like different rules apply, like to
• 6:31
  Speaker 1: baseballs and to electrons. The rules are fundamentally different. There
• 6:35
  Speaker 1: are different kinds of stuff and the rules that apply
• 6:37
  Speaker 1: to them are different, and that does feel weird, and
• 6:39
  Speaker 1: it's one of the most incredible things about the universe.
• 6:42
  Speaker 1: But a helpful way to think about it is in
• 6:44
  Speaker 1: terms of phases, Like think about water. Water has a
• 6:47
  Speaker 1: liquid phase and a solid phase and a gas phase.
• 6:50
  Speaker 1: Right in the end, we think it's all made out
• 6:52
  Speaker 1: of the same basic stuff water molecules, but they act
• 6:54
  Speaker 1: very differently under different circumstances. And you wouldn't expect the
• 6:58
  Speaker 1: laws of an ideal gas to describe what happens when
• 7:00
  Speaker 1: water crystallizes, or fluid dynamics to explain how a gas
• 7:04
  Speaker 1: would expand different rules apply in different scenarios, different phases,
• 7:08
  Speaker 1: And so we imagine that the universe is organized the
• 7:11
  Speaker 1: same way you can think of You can think of
• 7:13
  Speaker 1: it as sort of different phases where different rules apply.
• 7:16
  Speaker 1: What we don't know is if there is an underlying
• 7:19
  Speaker 1: theory behind all of it, the sort of physics version
• 7:23
  Speaker 1: of the water molecule, the tiniest little bits who's dancing
• 7:26
  Speaker 1: and tuing and froing and interacting is somehow making all
• 7:29
  Speaker 1: this other stuff emerge, even the quantum particles, even the baseballs,
• 7:33
  Speaker 1: even the galaxies. Is there something at the lowest level
• 7:37
  Speaker 1: which is determining everything from which all of our experience emerges.
• 7:42
  Speaker 3: So this is an interesting and confusing question to me,
• 7:45
  Speaker 3: because from my understanding, if we're all in the same universe,
• 7:51
  Speaker 3: we would all regardless of whether we're a human or
• 7:56
  Speaker 3: a quark or a kitten, we'd have to play by
• 7:59
  Speaker 3: the same rules.
• 8:01
  Speaker 2: But if the rules are.
• 8:04
  Speaker 3: Different somehow, right, like for a quark versus a kitten
• 8:08
  Speaker 3: in terms of physics, even though the kitten is also
• 8:10
  Speaker 3: made out of quarks or atoms molecules, it's hard for
• 8:15
  Speaker 3: me to wrap my head around there not being a
• 8:19
  Speaker 3: unifying set of rules that applies to everything, given that
• 8:24
  Speaker 3: not only do we live in the same universe, but
• 8:26
  Speaker 3: we're made out of all the same stuff.
• 8:29
  Speaker 1: Yeah, it's a great question, and a basic assumption about
• 8:32
  Speaker 1: a lot of physics is that that's possible that if
• 8:35
  Speaker 1: you zoom down to the smallest scale, you can find
• 8:37
  Speaker 1: the most basic set of rules, and that then you
• 8:40
  Speaker 1: could somehow zoom back out with the fundamental theory of
• 8:43
  Speaker 1: the universe in hand, you could explain everything it might
• 8:46
  Speaker 1: require you to calculate, like how ten to the twenty
• 8:48
  Speaker 1: nine particles come together to make a baseball. But the
• 8:51
  Speaker 1: idea is, in principle, it's all determined by what's happening
• 8:55
  Speaker 1: at the smaller scale, and when you zoom out, that's
• 8:58
  Speaker 1: just what those laws look like. And it might be
• 9:00
  Speaker 1: the case, right It might be that even though we
• 9:02
  Speaker 1: have trouble explaining how a zillion water droplets interacting in
• 9:06
  Speaker 1: the atmosphere make a hurricane, we can't even do it
• 9:09
  Speaker 1: with our fastest supercomputers. We think that probably it is
• 9:13
  Speaker 1: determined by that, but that's actually a philosophical assumption, and
• 9:17
  Speaker 1: some philosophers of science disagree with that. It's called strong
• 9:20
  Speaker 1: emergence at some point to lots of things that we
• 9:23
  Speaker 1: can't explain using underlying details. A great example is like
• 9:27
  Speaker 1: why you are here your consciousness. We have completely failed
• 9:31
  Speaker 1: so far to explain the experience of human consciousness in
• 9:34
  Speaker 1: terms of like the zapping of the little neurons inside
• 9:37
  Speaker 1: of our brains. It might be that somehow all that
• 9:39
  Speaker 1: stuff comes together to explain why you are experiencing this
• 9:42
  Speaker 1: podcast right now. But it might also be that there
• 9:45
  Speaker 1: are just different rules at different levels of the universe
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  Speaker 1: that aren't actually determined by the lower levels, that somehow
• 9:52
  Speaker 1: there are independent layers of the universe and different rules
• 9:56
  Speaker 1: apply at each one. It's a weird philosophy of the universe,
• 9:59
  Speaker 1: but it might also be our universe.
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  Speaker 3: That's very hard for my conscious brain to wrap itself around.
• 10:05
  Speaker 3: It is very interesting, this philosophical question of consciousness because
• 10:10
  Speaker 3: if we apply sort of the rules of like, well,
• 10:14
  Speaker 3: a brain works right because you have a communication between
• 10:17
  Speaker 3: many parts, you have neurons that are all communicating with
• 10:21
  Speaker 3: each other and forming these networks. Well, there's a lot
• 10:24
  Speaker 3: of things that do that, from computers to ant colonies,
• 10:29
  Speaker 3: and so the question is, well, are those things conscious
• 10:33
  Speaker 3: as well? And we can't really quantify that, and we
• 10:35
  Speaker 3: can't know whether even though it seems like there's this
• 10:40
  Speaker 3: underlying rule of you know, you require these sort of
• 10:43
  Speaker 3: individual units that are all communicating together and forming patterns,
• 10:47
  Speaker 3: and that's what you need for consciousness. If you see
• 10:50
  Speaker 3: that repeated in other systems, whether that actually applies to say,
• 10:54
  Speaker 3: can you recreate a consciousness with an electronic version of
• 10:59
  Speaker 3: neurons or or is something like a very complex ant
• 11:02
  Speaker 3: colony with thousands of ants?
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  Speaker 2: Does that recreate consciousness. So I guess in a way.
• 11:08
  Speaker 3: I could see how there could be different rules applying
• 11:12
  Speaker 3: to different layers, but it's just so strange and so like. Currently,
• 11:18
  Speaker 3: when we look at like quantum mechanics, it does not
• 11:22
  Speaker 3: do a good job of explaining physics on a larger scale.
• 11:27
  Speaker 1: Mostly we cannot connect the layers that we have. Even
• 11:30
  Speaker 1: though that's basically the motivation for the project to understand
• 11:34
  Speaker 1: everything at the smallest scale and use that to explain
• 11:37
  Speaker 1: everything else that's bigger, we have very rarely succeeded in
• 11:42
  Speaker 1: using a zoomed in microscopic approach to explain anything bigger.
• 11:46
  Speaker 4: You know.
• 11:46
  Speaker 1: One famous success story is ideal gases. Is say, okay,
• 11:50
  Speaker 1: we have this picture of atoms moving in a gas
• 11:52
  Speaker 1: as tiny little balls. Can we zoom out and think
• 11:55
  Speaker 1: about what happens to ten to the twenty nine balls,
• 11:58
  Speaker 1: and can we write equations that tell mathematical stories about
• 12:01
  Speaker 1: things that emerge from ten to the twenty nine tiny
• 12:05
  Speaker 1: little gas molecules like pressure and temperature and volume, and
• 12:08
  Speaker 1: we can you can actually derive, like the ideal gas
• 12:11
  Speaker 1: law from statistical mechanics explanations about the velocities of those
• 12:15
  Speaker 1: tiny little particles. That's a famous example because it's one
• 12:18
  Speaker 1: of the rare successes. Mostly we have failed because the
• 12:21
  Speaker 1: universe is kind of chaotic. It's really sensitive often to
• 12:24
  Speaker 1: these tiny little details. What happens to this quantum particle
• 12:27
  Speaker 1: affects another quantum particle, which affects another quantum particle. We
• 12:31
  Speaker 1: don't understand how to do that calculation. Most of the time,
• 12:34
  Speaker 1: we don't have the computing power, and we can't avoid
• 12:36
  Speaker 1: this chaos problem. So mostly we don't know how to
• 12:39
  Speaker 1: do that. It might be that it is determined and
• 12:41
  Speaker 1: it's possible to do those calculations, is just sort of
• 12:44
  Speaker 1: beyond our ability right now. Or it might be that
• 12:47
  Speaker 1: it's just not that different rules apply in different regimes,
• 12:50
  Speaker 1: as weird as that is.
• 12:52
  Speaker 3: So, I guess I'm not so familiar with quantum mechanics
• 12:56
  Speaker 3: and general relativity. Can we kind of just hammer down,
• 13:01
  Speaker 3: like what are those two things? How Like what do
• 13:04
  Speaker 3: they apply to and what don't they apply to?
• 13:07
  Speaker 1: So at the forefront of our understanding of the most
• 13:09
  Speaker 1: microscopic picture of how the universe works, we have two
• 13:13
  Speaker 1: basic theories. We have quantum mechanics, which tells us about
• 13:16
  Speaker 1: really tiny stuff, and general relativity, which tells us about
• 13:19
  Speaker 1: really big, heavy stuff, basically quantum mechanics for particles and
• 13:23
  Speaker 1: general relativity for gravity. One of the biggest frustrations in
• 13:26
  Speaker 1: physics in the last one hundred years has been our
• 13:29
  Speaker 1: inability to bring them together into a single story, to
• 13:32
  Speaker 1: weave them into a unified picture of how the universe works.
• 13:36
  Speaker 1: You know, this whole project of like, let's explain everything
• 13:38
  Speaker 1: from the tiniest particles and then zoom out. Well, we
• 13:40
  Speaker 1: haven't even succeeded in explaining the tinese particles yet, but
• 13:43
  Speaker 1: there's a vigorous program of people working on this stuff.
• 13:46
  Speaker 1: And in today's episode, we're going to dig into one
• 13:48
  Speaker 1: of the most recent and weirdest ideas about how to
• 13:52
  Speaker 1: bring quantum mechanics and relativity together. So on today's episode,
• 13:56
  Speaker 1: we're going to be answering the question, what is quantum relativity?
• 14:05
  Speaker 3: Hmmm, quantum relativity. So it's like quantum mechanics and general
• 14:11
  Speaker 3: relativity had a baby.
• 14:15
  Speaker 1: It also sounds like the buzzword name for a startup
• 14:18
  Speaker 1: where you're like, I don't even really know what it
• 14:20
  Speaker 1: they do, but it sounds pretty good. So before we
• 14:23
  Speaker 1: dig into the details of this, I checked in with
• 14:25
  Speaker 1: our listeners to see if they had any idea about
• 14:28
  Speaker 1: the theory of quantum relativity, if they had heard this before,
• 14:32
  Speaker 1: if they had thoughts about it. Thanks very much to
• 14:34
  Speaker 1: everybody who participates in this audience feedback segment of the podcast.
• 14:38
  Speaker 1: We really love hearing your voice and hearing your thoughts
• 14:41
  Speaker 1: on the question of the day. If you would like
• 14:43
  Speaker 1: to participate, please don't be shy. Just write to me
• 14:46
  Speaker 1: to Questions at Danielandjorge dot com and I'll hook you up.
• 14:50
  Speaker 1: So before you hear these answers, think to yourself, have
• 14:53
  Speaker 1: you heard of quantum relativity? What do you think that
• 14:57
  Speaker 1: might mean. Here's what some listeners have to say.
• 15:00
  Speaker 2: Quantum relativity.
• 15:02
  Speaker 4: I'm guessing that is the theory that brings quantum mechanics
• 15:06
  Speaker 4: and general relativity together. So something that the theory that
• 15:13
  Speaker 4: figures out how you work gravity and quantum mechanics together.
• 15:17
  Speaker 4: Since gravity, we're not quite sure how that works on
• 15:20
  Speaker 4: the smallest scales.
• 15:22
  Speaker 1: That is really really tiny relativity.
• 15:25
  Speaker 5: To me, that sounds like a parallel to general relativity.
• 15:29
  Speaker 5: So I bet that it has to do with how
• 15:32
  Speaker 5: particles interact with each other when in proximity to each
• 15:36
  Speaker 5: other on a quantum scale.
• 15:37
  Speaker 3: I love the answer really tiny relativity because it makes
• 15:42
  Speaker 3: me think of some ants or some mites or tartar
• 15:46
  Speaker 3: grades in the lab coats drawing on tiny chalkboards.
• 15:51
  Speaker 1: Exactly. Also, quantum just sometimes means like fancy or stinazzi,
• 15:55
  Speaker 1: or we're going to charge an extra ten bucks for it,
• 15:57
  Speaker 1: So like expensive relativity.
• 16:00
  Speaker 3: This is a quantum salad for twelve dollars, exactly.
• 16:06
  Speaker 1: I'd like to upgrade my salad, actually do a quantum salad.
• 16:09
  Speaker 1: Or I ordered quantum on my salad and I didn't
• 16:11
  Speaker 1: get enough.
• 16:13
  Speaker 2: Could mean anything thanks in.
• 16:14
  Speaker 1: A complaint anything. Well, we're going to see today. The
• 16:19
  Speaker 1: quantum relativity is the name of a new effort to
• 16:22
  Speaker 1: unify quantum mechanics and general relativity, and they really do
• 16:25
  Speaker 1: give it that name for a reason. But before that's
• 16:28
  Speaker 1: going to make any sense to us, we really have
• 16:30
  Speaker 1: to understand the basics of like what is quantum mechanics
• 16:33
  Speaker 1: in general relativity, why do we want to unify them,
• 16:35
  Speaker 1: and why is it so hard?
• 16:38
  Speaker 2: Right?
• 16:38
  Speaker 3: Yes, because, like you were kind of saying earlier, general
• 16:42
  Speaker 3: relativity is for big stuff.
• 16:44
  Speaker 2: Quantum mechanics is for tiny stuff.
• 16:47
  Speaker 3: But it's got to be a little more detailed than
• 16:49
  Speaker 3: that I would imagine.
• 16:52
  Speaker 1: No, that's basically it take quantu mechanics, generativity. It's like
• 16:55
  Speaker 1: all done in fifteen minutes. But listeners of the podcast
• 16:58
  Speaker 1: will remember that general relativity based describes space and time.
• 17:02
  Speaker 1: Special relativity is a theory that tells us about how
• 17:05
  Speaker 1: light moves and how observers always see light moving at
• 17:08
  Speaker 1: the same speed, and general relativity is what explains gravity.
• 17:13
  Speaker 1: Remember Newton had the idea that gravity was a force
• 17:15
  Speaker 1: that things with mass pulled on each other and that's
• 17:18
  Speaker 1: why the Earth goes around the Sun and you feel
• 17:21
  Speaker 1: like you're falling towards the Earth because he described gravity
• 17:24
  Speaker 1: as this force. But Einstein tells us that gravity is
• 17:27
  Speaker 1: not a force. A gravity is not capable of accelerating anything,
• 17:31
  Speaker 1: and that things are actually moving according to the invisible
• 17:34
  Speaker 1: curvature of space and time.
• 17:36
  Speaker 3: This is the thing that is so hard for me
• 17:39
  Speaker 3: to really visualize or hold in my head because every
• 17:43
  Speaker 3: kind of analogy I try to make is based in physics,
• 17:48
  Speaker 3: like a ball rolling down a hill or something, or
• 17:53
  Speaker 3: you know, I think of the fabric of space being
• 17:56
  Speaker 3: sort of pulled in a certain direction, and it's like
• 17:58
  Speaker 3: that's still physics. In the sun and so of like
• 18:01
  Speaker 3: you know, a fabric being pulled and something falling into it.
• 18:05
  Speaker 3: Whereas like the idea of gravity being sort of the
• 18:09
  Speaker 3: shape of the universe in a way that like makes
• 18:13
  Speaker 3: sense in my head is very hard to grasp. I
• 18:16
  Speaker 3: understand it in a certain way, but to visualize it
• 18:19
  Speaker 3: is so difficult.
• 18:20
  Speaker 1: It is very tricky because it changes your entire concept
• 18:24
  Speaker 1: of what space is.
• 18:25
  Speaker 3: Right.
• 18:26
  Speaker 1: We used to thinking of space as like nothingness and
• 18:28
  Speaker 1: stuff is there and it can move through space. But
• 18:31
  Speaker 1: it turns out that there is something to space, like
• 18:34
  Speaker 1: between two points, there's information information about how that space
• 18:39
  Speaker 1: is curved or bent, and that affects how stuff moves
• 18:42
  Speaker 1: through that space. And yeah, there's a lot of examples
• 18:45
  Speaker 1: out there in popular science literature. I think most of
• 18:47
  Speaker 1: which are very confusing. You know, the idea of like
• 18:50
  Speaker 1: a rubber sheet and you have a ball on the sheet,
• 18:53
  Speaker 1: and the rubber sheet is bent and that makes things curved.
• 18:55
  Speaker 1: That's very confusing because you still have to have gravity
• 18:57
  Speaker 1: in that example in the vertical direction. You have this
• 19:00
  Speaker 1: like external third dimension of gravity in your two D world.
• 19:03
  Speaker 1: I think that's very very misleading. I prefer to think
• 19:06
  Speaker 1: about it in three D. And remember that this curvature
• 19:08
  Speaker 1: is intrinsic. It's not external. It's not like there's somebody
• 19:12
  Speaker 1: else out there with a ruler in real space who's
• 19:15
  Speaker 1: telling us our space is bent relative to their space.
• 19:18
  Speaker 1: The curvature is intrinsic. There's no external ruler. It just
• 19:21
  Speaker 1: means that the relative distances between two points change, which
• 19:25
  Speaker 1: means like the shortest path from A to B might
• 19:28
  Speaker 1: not be a straight line that you would draw if
• 19:32
  Speaker 1: you ignore the curvature. Once you know what the curvature is,
• 19:34
  Speaker 1: there might be a shorter path between A and B,
• 19:37
  Speaker 1: and that's the path that light will take. Light always
• 19:39
  Speaker 1: takes the shortest path between two points.
• 19:42
  Speaker 3: So if I'm standing on my bed and I'm going
• 19:46
  Speaker 3: to jump off the bed, as I do every morning,
• 19:48
  Speaker 3: so I am subject to the gravity of Earth, and
• 19:53
  Speaker 3: it's not so much that it's pulling me down, but
• 19:56
  Speaker 3: just that I am traveling along the short this path
• 20:00
  Speaker 3: from point A, which is my bed, to point B,
• 20:04
  Speaker 3: which is the other point of space. But it's more
• 20:07
  Speaker 3: or less just interrupted by the floor.
• 20:09
  Speaker 1: Yeah, that's a great example. Let's think about it first
• 20:12
  Speaker 1: from the Newtonian point of view, and then let's reboot
• 20:15
  Speaker 1: and think about it from an Einsteinian point of view.
• 20:17
  Speaker 1: So Newton would say, you're standing on your bed. There's
• 20:20
  Speaker 1: the force of gravity pulling down on you from the Earth,
• 20:23
  Speaker 1: and there's the force of your bed pushing up, and
• 20:25
  Speaker 1: those two things are balanced, so you're not going anywhere.
• 20:27
  Speaker 1: Then you jump off your bed. No longer is the
• 20:30
  Speaker 1: bed pushing you up, and so now you're falling because
• 20:32
  Speaker 1: it's just the force of gravity, and that's accelerating you
• 20:35
  Speaker 1: down towards the center of the Earth. That's the way
• 20:36
  Speaker 1: people mostly learn about gravity. That's how Newton described it.
• 20:39
  Speaker 1: That's where we start. Einstein says something different. Einstein says, well,
• 20:43
  Speaker 1: when you're standing on your bed, you actually are being accelerated.
• 20:47
  Speaker 1: There's only one force there. There's the force of your bed.
• 20:50
  Speaker 1: What's it pushing you against. It's pushing you against your
• 20:52
  Speaker 1: natural motion, which is to fall towards the center of
• 20:56
  Speaker 1: the earth. So Newton says, you're accelerating when after you
• 20:59
  Speaker 1: jump off the bed and you're falling towards the center.
• 21:01
  Speaker 1: Einstein says, no, you were accelerating when you were on
• 21:04
  Speaker 1: your bed. It's when you jump off your bed that
• 21:07
  Speaker 1: you're now following the natural curvature of space. You're no
• 21:11
  Speaker 1: longer accelerating. The only force in this scenario is the
• 21:14
  Speaker 1: force of the bed on you, and that's keeping you
• 21:18
  Speaker 1: from naturally moving towards the center of the Earth. When
• 21:20
  Speaker 1: you're standing on the bed. Once you jump off, you're
• 21:23
  Speaker 1: the one in free fall. And you can actually measure
• 21:25
  Speaker 1: this because you can take an accelerometer, something which measures
• 21:28
  Speaker 1: your acceleration. I mean, the scale is basically a gravitometer,
• 21:33
  Speaker 1: and you can measure when are you feeling an acceleration.
• 21:36
  Speaker 1: If you jump off your bed and you're holding a scale,
• 21:37
  Speaker 1: you put it under your feet, what are you going
• 21:39
  Speaker 1: to weigh? You're going to weigh nothing because there's no
• 21:41
  Speaker 1: force between you and the scale. But if the scale's
• 21:44
  Speaker 1: on your bed and you're standing on it, then you're
• 21:46
  Speaker 1: going to see your weight. And that's because that's where
• 21:48
  Speaker 1: you're accelerating. It's when you're on your bed.
• 21:50
  Speaker 3: That's so interesting. Yeah, I can totally visualize that. Also,
• 21:54
  Speaker 3: I knew that when I sleep in, I wasn't lazy
• 21:57
  Speaker 3: because I've been accelerating the whole time.
• 22:02
  Speaker 1: So this is Einstein's picture of gravity, and it's massively successful.
• 22:06
  Speaker 3: Right.
• 22:06
  Speaker 1: It describes the motion of everything in the universe, the
• 22:08
  Speaker 1: expansion of the universe, incredibly high precision black holes oscillating
• 22:13
  Speaker 1: around each other, neutron stars getting gobbled by black holes,
• 22:16
  Speaker 1: gravitational waves. It's been tested in and out and up
• 22:19
  Speaker 1: the wazoo for decades and decades, and it's this beautiful
• 22:23
  Speaker 1: geometric picture of the universe that tells us gravity is
• 22:26
  Speaker 1: not a force. It's just the way things are flowing
• 22:29
  Speaker 1: through the geometry of space and time. And the things
• 22:32
  Speaker 1: to take away from this discussion are that it's one
• 22:34
  Speaker 1: deterministic right. It says that things move in a certain
• 22:37
  Speaker 1: way because of geometry. It's no randomness, there's no probability.
• 22:41
  Speaker 1: It's not like when you jump off your bed you
• 22:43
  Speaker 1: have a chance of landing here or there. It's determined
• 22:45
  Speaker 1: by exactly where you are in the shape of space.
• 22:48
  Speaker 1: And the other is that it mostly affects really really
• 22:51
  Speaker 1: big stuff because gravity is super weak. Whether it's a
• 22:54
  Speaker 1: force or it's the curvature of space time, it takes
• 22:57
  Speaker 1: a lot of mass to have any effect. You can
• 23:00
  Speaker 1: overcome all the gravity of the Earth or the curvature
• 23:03
  Speaker 1: of space and time caused by the Earth using a
• 23:05
  Speaker 1: simple kitchen magnet right, or your legs can overcome it.
• 23:09
  Speaker 1: You can leap off the surface of the Earth, which
• 23:11
  Speaker 1: means it applies mostly to really massive objects. So it's
• 23:15
  Speaker 1: deterministic and it applies to really massive stuff. That's the
• 23:19
  Speaker 1: important things to remember when we're going to talk about
• 23:21
  Speaker 1: trying to integrate it with quantum mechanics.
• 23:23
  Speaker 3: Because that's in the opposite direction where it is extremely
• 23:27
  Speaker 3: extremely tiny stuff like as a human being, gravity is
• 23:33
  Speaker 3: something where it's hard to you know, really visualize like
• 23:37
  Speaker 3: the scope of say like the size of the Sun
• 23:41
  Speaker 3: or this even the size of the planet. Sure you
• 23:43
  Speaker 3: can go on a plane and kind of see part
• 23:46
  Speaker 3: of it, but it's it's still hard to visualize how
• 23:49
  Speaker 3: big these things are, how massive it is, and then similarly,
• 23:53
  Speaker 3: going into quantum mechanics visualizing how tiny these things can be.
• 23:57
  Speaker 3: So there really as opposite as you can can get
• 24:00
  Speaker 3: in terms of size and scope.
• 24:03
  Speaker 1: They are like the ying and ying of physics. But
• 24:06
  Speaker 1: we hope they click together to make a holistic picture.
• 24:11
  Speaker 1: But let's dig into how quant mechanics explains the tiniest
• 24:14
  Speaker 1: stuff in the universe. But first let's take a quick break.
• 24:17
  Speaker 3: All right, I'm going to try to start thinking small
• 24:32
  Speaker 3: all right, I'm trying to think inside a very tiny box,
• 24:38
  Speaker 3: and hopefully that will help me.
• 24:41
  Speaker 1: As you mentioned already, the rules seem to be different
• 24:44
  Speaker 1: for things like baseball and planets than things like electrons
• 24:49
  Speaker 1: and photons and tiny little particles, which is really the
• 24:52
  Speaker 1: source of one of the biggest mysteries in modern physics,
• 24:56
  Speaker 1: how that all works and whether we can bring it.
• 24:58
  Speaker 3: Together right, Because I think I had some concept before
• 25:04
  Speaker 3: ever coming on this show, which is that like with
• 25:07
  Speaker 3: the small stuff, the really tiny quantum level stuff, there
• 25:11
  Speaker 3: was some sort.
• 25:12
  Speaker 2: Of like average you could take.
• 25:14
  Speaker 3: Of its behavior, and then that would be well integrated into, say,
• 25:19
  Speaker 3: other types of physics like general relativity, where it's like, well,
• 25:23
  Speaker 3: you know, you just scale up averages of the small
• 25:26
  Speaker 3: stuff's activity and then that would fit in some perfect
• 25:29
  Speaker 3: formula and represent general relativity.
• 25:33
  Speaker 2: But turns out it's not so simple.
• 25:37
  Speaker 5: No.
• 25:37
  Speaker 1: It turns out the rules of these two concepts are
• 25:39
  Speaker 1: fundamentally different and tell really different stories about the nature
• 25:43
  Speaker 1: of the universe we live in. About one hundred years ago,
• 25:46
  Speaker 1: people did experiments which showed us that when you zoom
• 25:49
  Speaker 1: into the tiniest level, the rules really do seem to
• 25:51
  Speaker 1: be different. Amazingly, it was Einstein who played a role
• 25:54
  Speaker 1: in both of these revolutions. He of course came up
• 25:57
  Speaker 1: with relativity, but he also had the idea of how
• 26:00
  Speaker 1: to interpret the photoelectric effect, which kicked off the entire
• 26:03
  Speaker 1: quantum revolution as well, So that dude was pretty central.
• 26:07
  Speaker 2: What's the photo reflective effect?
• 26:10
  Speaker 1: This is the experiment where you shine bright light at
• 26:12
  Speaker 1: a piece of metal and you see a bunch of
• 26:14
  Speaker 1: electrons boil off. And the idea is, Okay, the electrons
• 26:17
  Speaker 1: are absorbing the light, they're getting energy, they're boiling off.
• 26:20
  Speaker 1: The weird thing about the experiment was as you turn
• 26:23
  Speaker 1: up the brightness of the light, like the intensity of
• 26:26
  Speaker 1: the light, you expected to get electrons with more energy
• 26:29
  Speaker 1: because you're shining brighter light at it. But instead what
• 26:31
  Speaker 1: you got were more electrons. And this really puzzled people.
• 26:35
  Speaker 1: They're like, why can't the electrons get more energy? And
• 26:38
  Speaker 1: the answer in the end is that light is made
• 26:40
  Speaker 1: of these tiny little packets. It's not a continuous beam.
• 26:43
  Speaker 1: It's a bunch of little packets of energy, and each
• 26:46
  Speaker 1: electron can basically only absorb one. It's like one interaction
• 26:49
  Speaker 1: between a photon and n electron. So when you turn
• 26:52
  Speaker 1: up the brightness of the beam, which you get are
• 26:55
  Speaker 1: more electrons absorbing photons, not one electron absorbing more photons.
• 27:00
  Speaker 1: And so that was the clue that told people, oh, look,
• 27:02
  Speaker 1: maybe light is made of these little packets, and that
• 27:05
  Speaker 1: kicked off the whole quantum revolution that showed us that
• 27:08
  Speaker 1: everything out there is actually made of these little discrete
• 27:10
  Speaker 1: bits that follow very different rules.
• 27:12
  Speaker 3: It's like these electrons are flying ryanair and they can
• 27:15
  Speaker 3: only have one packet per electron.
• 27:19
  Speaker 1: That's right. Otherwise you get some quantum fees carry ons.
• 27:23
  Speaker 3: Is that a very small fee or a very big fee?
• 27:27
  Speaker 1: Small fees that add up to a lot because of
• 27:31
  Speaker 1: interference with your pocketbook?
• 27:32
  Speaker 2: I think? Ain't that how it is?
• 27:34
  Speaker 1: Anybody out there who works for the airlines, do not
• 27:36
  Speaker 1: take this as a creative idea for how to add fees. Okay,
• 27:38
  Speaker 1: I don't want to see quantum fees on my quantum fees.
• 27:41
  Speaker 2: That's going to be the next thing.
• 27:44
  Speaker 1: And what emerged from the next twenty or thirty years
• 27:46
  Speaker 1: of studying experiments and shining lights on things and looking
• 27:50
  Speaker 1: inside the atom, or a new set of rules for
• 27:53
  Speaker 1: how tiny stuff worked. This tiny stuff didn't follow the
• 27:56
  Speaker 1: rules of planets and baseballs. You couldn't make a picture
• 27:59
  Speaker 1: of the atom that literally had electrons orbiting the center
• 28:03
  Speaker 1: of the atom. That just didn't work. The physics of
• 28:05
  Speaker 1: it didn't make sense. Those electrons in an orbit would
• 28:08
  Speaker 1: radiate away all their energy and collapse into the nucleus
• 28:11
  Speaker 1: because anything that's moving in a circle is accelerating, and
• 28:14
  Speaker 1: things that accelerate have to give off radiation in order
• 28:17
  Speaker 1: to keep bending. But we don't see electrons collapsing into
• 28:20
  Speaker 1: the center of the atom and tend to the negative
• 28:22
  Speaker 1: thirteen seconds. I told us that the rules were fundamentally different,
• 28:26
  Speaker 1: and we came up with a completely new kind of mathematics,
• 28:29
  Speaker 1: quantum mechanics, Schrodinger's equation that described the rules of the
• 28:33
  Speaker 1: quantum realm, which were totally different from the rules of
• 28:36
  Speaker 1: baseballs and electrons. Base Balls move through space. They have
• 28:40
  Speaker 1: a path, like they're here and then they are there,
• 28:43
  Speaker 1: and so you know they went from here to there.
• 28:46
  Speaker 1: They have a location at every moment, and you can
• 28:48
  Speaker 1: string those locations together to make a smooth and continuous path.
• 28:52
  Speaker 1: Just sort of makes sense to you that everything has
• 28:53
  Speaker 1: to be somewhere at all times. But electrons don't follow
• 28:57
  Speaker 1: those rules. That's an intuition you developed from your experi
• 29:00
  Speaker 1: of baseballs and rocks and other kinds of stuff. Electrons
• 29:03
  Speaker 1: can be here and then they can be there, and
• 29:06
  Speaker 1: they don't have to go from here to there. They
• 29:09
  Speaker 1: don't always have to have a determined location. They can
• 29:12
  Speaker 1: exist in probabilistic form where they can say, well, I
• 29:15
  Speaker 1: might be here and I might be there. It's not
• 29:18
  Speaker 1: determined much more than just being not known. It's actually
• 29:22
  Speaker 1: not determined by the universe.
• 29:24
  Speaker 3: Right, Because it's hard to understand this sometimes where you
• 29:28
  Speaker 3: think in these kinds of thought experiments of like an
• 29:31
  Speaker 3: electron not knowing sort of the location of electron or
• 29:36
  Speaker 3: the spin of something. It's like I think sometimes I
• 29:39
  Speaker 3: have this concept of like, well, this is just sort
• 29:42
  Speaker 3: of some kind of weird math. It's not actually describing
• 29:45
  Speaker 3: what's actually happening. But I would assume there's like evidence
• 29:50
  Speaker 3: that is what's actually happening, that this is not these
• 29:53
  Speaker 3: positions are not have experimentally been shown to not be
• 29:57
  Speaker 3: like determined by the universe.
• 29:59
  Speaker 1: Yeah, there's a whole really fascinating set of experiments that
• 30:02
  Speaker 1: explore this question, like is it just something we don't
• 30:05
  Speaker 1: know or is it really undetermined by the universe. Is
• 30:09
  Speaker 1: there some like extra information the electron is carrying that
• 30:12
  Speaker 1: we're just not aware of that actually tells where the
• 30:15
  Speaker 1: universe is, like keeping track of where it really is,
• 30:18
  Speaker 1: and we just don't know. And it's a set of
• 30:20
  Speaker 1: experiments proposed by John Bell to probe a theory called
• 30:23
  Speaker 1: Bell's inequalities, and we have a whole set of podcasts
• 30:26
  Speaker 1: about those Whether quantum mechanics really is random or not.
• 30:29
  Speaker 1: And the upshot is that it seems like it really
• 30:32
  Speaker 1: is random. There are some loopholes there, how you might
• 30:35
  Speaker 1: have like some sort of like non local pilot wave
• 30:37
  Speaker 1: that's controlling the whole universe. But the most mainstream interpretation
• 30:41
  Speaker 1: is that it really is random. There really is some
• 30:44
  Speaker 1: non determinism to the universe that you could do the
• 30:48
  Speaker 1: same experiment twice, exactly the same setup and get different answers.
• 30:52
  Speaker 1: Like you're shoot an electron into an experiment with exactly
• 30:55
  Speaker 1: the same conditions twice and it'll end up going left
• 30:58
  Speaker 1: once and it'll end up going right on another time.
• 31:00
  Speaker 1: There's like a die being thrown by the universe to
• 31:03
  Speaker 1: determine where an electron goes. It's crazy, it's bonkers, but
• 31:06
  Speaker 1: that's the universe we live in.
• 31:08
  Speaker 3: So it'd be like if you like, you know, there's
• 31:11
  Speaker 3: the classic thing that even babies. This is so interesting
• 31:14
  Speaker 3: about human cognition is that babies have a sort of
• 31:18
  Speaker 3: baseline understanding of physics. It seems like if they see
• 31:22
  Speaker 3: a little marble hit a big marble, they don't expect
• 31:25
  Speaker 3: the big marble to go flying off.
• 31:27
  Speaker 2: And if you show them that, they.
• 31:28
  Speaker 3: Look they kind of stare at it because it's surprising
• 31:31
  Speaker 3: to them. But you know, because we kind of have
• 31:34
  Speaker 3: this this innate understanding that if a little thing hits
• 31:37
  Speaker 3: a big thing, the big thing isn't going to go
• 31:38
  Speaker 3: shooting off, whereas if the big thing hits the little thing,
• 31:41
  Speaker 3: it's going to go shooting off. And like, if we
• 31:44
  Speaker 3: hit things at a certain angle, it's gonna, you know,
• 31:47
  Speaker 3: go at a certain direction, just like I guess that's
• 31:51
  Speaker 3: how people can be good at pool, not me, but
• 31:54
  Speaker 3: other people. And so it would be shocking though, if
• 31:58
  Speaker 3: you're if you're good at pool and you something at
• 32:00
  Speaker 3: a certain angle and it's just completely random about of
• 32:05
  Speaker 3: whether it goes left or right, or forward or backwards
• 32:08
  Speaker 3: or up or down.
• 32:09
  Speaker 1: It is a really weird way to think about the universe.
• 32:12
  Speaker 1: I was recently trying to explain this stuff to my
• 32:14
  Speaker 1: sixteen year old who's taking chemistry and was learning about
• 32:16
  Speaker 1: the atomic structure and all this stuff and photons and probabilities,
• 32:21
  Speaker 1: and it was pretty bewildering. But it was a fun
• 32:23
  Speaker 1: experience to try to download into his mind this new
• 32:25
  Speaker 1: way of thinking about the universe. But it really is
• 32:28
  Speaker 1: counterintuitive because you don't ever experience it. And that's one
• 32:31
  Speaker 1: of the big mysteries of quantum mechanics, is why not.
• 32:34
  Speaker 1: Because when we interact with quantum stuff, it tends to collapse.
• 32:38
  Speaker 1: It says, Oh, I have a bunch of possibilities, but
• 32:39
  Speaker 1: I'm just going to pick one now. When a photon
• 32:42
  Speaker 1: hits your eyeball, it decides, Oh, I'm here or I'm there.
• 32:44
  Speaker 1: When a electron hits the screen, the universe decides. For
• 32:48
  Speaker 1: some reason, the universe has this distinction between tiny little
• 32:51
  Speaker 1: stuff that can exist with uncertainty and bigger stuff which can't.
• 32:55
  Speaker 1: People sometimes describe this as acting like a particle or
• 32:58
  Speaker 1: acting like a wave. Really is between classical physics like
• 33:02
  Speaker 1: general relativity that's talking about stuff having specific locations and
• 33:06
  Speaker 1: quantum physics, where stuff can still have.
• 33:08
  Speaker 3: Uncertainty, So quantum physics would be the particle, and general
• 33:13
  Speaker 3: relativity would be the wave, or vice versa.
• 33:15
  Speaker 1: So quantu physics is about tiny little stuff, but it's
• 33:18
  Speaker 1: the wave like behavior of that stuff that's really weird
• 33:21
  Speaker 1: because the wave appears in the Shortener equation, and people
• 33:24
  Speaker 1: tend to think about particles as having like a definite location,
• 33:27
  Speaker 1: like you've seen this particle on the screen. So general
• 33:30
  Speaker 1: relativity and classical physics more broadly thinks about stuff as
• 33:33
  Speaker 1: having definitive locations. It is here, it is there, it
• 33:36
  Speaker 1: was here, And quantum mechanics says that there can be uncertainty.
• 33:40
  Speaker 1: So quantum is the more wavy stuff, and in this case,
• 33:43
  Speaker 1: the classical theory is more like definitive locations, which people
• 33:47
  Speaker 1: sometimes describe as acting like a particle.
• 33:50
  Speaker 3: So quantum mechanics is kind of whibbly wobbly.
• 33:53
  Speaker 1: Yeah, that's exactly right. So these are two very different
• 33:57
  Speaker 1: pictures of the world. Right, things moving along classical pass
• 34:01
  Speaker 1: where they always have a definitive location at every time,
• 34:04
  Speaker 1: or things being wibbly wobbling, being undetermined. And you might think, well,
• 34:07
  Speaker 1: it should be pretty easy to figure out which is right,
• 34:10
  Speaker 1: can't we do experiments to tell us which one is
• 34:13
  Speaker 1: predicting things correctly. Right, Often you have two theories, you
• 34:16
  Speaker 1: just do an experiment, you say, well, which one is right,
• 34:19
  Speaker 1: And the problem is that it's so hard to do
• 34:21
  Speaker 1: an experiment where both of them have something to say.
• 34:25
  Speaker 1: Most of the universe is divided up into stuff where
• 34:27
  Speaker 1: general relativity is important and quantum mechanics can be ignored,
• 34:31
  Speaker 1: like the motion of planets, or stuff where quantum mechanics
• 34:35
  Speaker 1: is important and general relativity can be ignored, like two
• 34:38
  Speaker 1: electrons bouncing off of each other.
• 34:41
  Speaker 3: Right, Like you could do a physics experiment on a baseball,
• 34:45
  Speaker 3: But then to do a physics experiment and a quantum
• 34:49
  Speaker 3: level experiment on the baseball's electrons at the same time
• 34:52
  Speaker 3: in a way that makes sense seems very difficult.
• 34:56
  Speaker 1: Exactly when you do an experiment with baseballs, you can
• 34:58
  Speaker 1: pretty much ignore the fact that it's made from ten
• 35:01
  Speaker 1: to twenty nine tiny buzzing particles, and you can just
• 35:04
  Speaker 1: use Newton's laws F equals MA to describe its path
• 35:07
  Speaker 1: very very accurately. That's because the quantum effects tend to
• 35:10
  Speaker 1: average out for reasons. Again, we don't really know how
• 35:13
  Speaker 1: that works or why that works. But it does, so
• 35:15
  Speaker 1: quantum effects tend to disappear when you zoom out far enough.
• 35:18
  Speaker 1: On the other hand, when you zoom in far enough,
• 35:21
  Speaker 1: gravity is so weak that it becomes irrelevant. Like we
• 35:24
  Speaker 1: do collisions between protons all the time at the Large
• 35:26
  Speaker 1: Hadron Collider, but we always ignore their gravity, Like there
• 35:30
  Speaker 1: is a gravitational attraction we think between the protons, but
• 35:34
  Speaker 1: protons have such tiny masses that we can essentially ignore
• 35:37
  Speaker 1: their gravity when we do those calculations.
• 35:40
  Speaker 3: I mean that makes sense because even though technically, even
• 35:43
  Speaker 3: as people, we have gravity, it's not like we can
• 35:46
  Speaker 3: suck things into ourselves. I know that's not how gravity works,
• 35:50
  Speaker 3: but still we're not. We are not generating enough of
• 35:54
  Speaker 3: a gravitational effect that things, you know, fall into our bodies.
• 35:59
  Speaker 2: And so what chance does a proton have?
• 36:02
  Speaker 1: Exactly, you can't blame gravity for the reason you ate
• 36:05
  Speaker 1: that pint of ice cream. It didn't just like fall
• 36:07
  Speaker 1: into your body.
• 36:08
  Speaker 2: That was my alibi.
• 36:10
  Speaker 1: But that's exactly right. We could hardly even measure the
• 36:13
  Speaker 1: gravity between things that are like a kilogram. The smallest
• 36:17
  Speaker 1: thing we've ever measured gravity for is just about a kilogram,
• 36:20
  Speaker 1: and protons are a tiny, tiny fraction of that. We're
• 36:24
  Speaker 1: like thirty orders of magnitude away from being able to
• 36:27
  Speaker 1: measure the gravity of a proton. And more than that,
• 36:30
  Speaker 1: we don't even understand what the gravity of a proton
• 36:33
  Speaker 1: would look like. You know, say you have a particle
• 36:35
  Speaker 1: with uncertainty to it. Maybe it's here, maybe it's there,
• 36:38
  Speaker 1: maybe it's in this third location you don't know. The
• 36:41
  Speaker 1: universe says, that's cool, the particle can be uncertain, all right,
• 36:44
  Speaker 1: But then what is the gravity of an uncertain particle?
• 36:48
  Speaker 1: Does it have a little bit of curvature over here
• 36:50
  Speaker 1: because it might be over there, and a little bit
• 36:51
  Speaker 1: of curvature over there because it might be over there.
• 36:54
  Speaker 1: Is the curvature of space itself uncertain? We don't know
• 36:58
  Speaker 1: how to unify these two ideas of quantum mechanics and
• 37:01
  Speaker 1: of gravity. Nobody really knows how that can be done.
• 37:04
  Speaker 3: That's so interesting and uncomfortable from a sort of biology perspective,
• 37:10
  Speaker 3: because when you look at biology, big stuff is made
• 37:15
  Speaker 3: out of small stuff, and so that tracks. But when
• 37:19
  Speaker 3: you look at biological processes, like you look at a cell,
• 37:23
  Speaker 3: and it's interesting because, of course, on a certain level,
• 37:27
  Speaker 3: each cell's activity does not necessarily explain everything about a
• 37:32
  Speaker 3: human being or a cat or a dog their behavior.
• 37:36
  Speaker 3: But you can generally track how the small stuff creates
• 37:42
  Speaker 3: the big stuff. And there's generally some like the rules
• 37:45
  Speaker 3: that govern the small stuff, these biological processes that govern
• 37:49
  Speaker 3: the small stuff. You can track how that is impacting
• 37:53
  Speaker 3: the big stuff. Like you chug a bunch of soy sauce,
• 37:56
  Speaker 3: and those salt ions are you know, messing up your
• 38:00
  Speaker 3: or your ion channels in your brain, and then that's
• 38:03
  Speaker 3: why you're in a coma. So it's you know, it's
• 38:07
  Speaker 3: very uncomfortable, this idea that you couldn't track, like, okay,
• 38:11
  Speaker 3: so this proton is acting in a certain way, and
• 38:14
  Speaker 3: then we can scale up to you know, an item
• 38:18
  Speaker 3: like a watermelon, because it has a bunch of protons
• 38:22
  Speaker 3: in it.
• 38:23
  Speaker 2: We know how that the behavior.
• 38:25
  Speaker 3: Of those protons would somehow affect the behavior of the
• 38:28
  Speaker 3: watermelon exactly.
• 38:30
  Speaker 1: And we'd love to do an experiment where we could
• 38:32
  Speaker 1: study that right, where we could take something where quantum
• 38:36
  Speaker 1: mechanics was relevant and also gravity was relevant, Like if
• 38:40
  Speaker 1: we could take enough protons and squeeze them together and
• 38:43
  Speaker 1: keep them in a small enough space so they're still
• 38:46
  Speaker 1: being quantum mechanical, but we had enough protons where we
• 38:49
  Speaker 1: could also measure its gravity. That way we could understand,
• 38:53
  Speaker 1: like how the small stuff is affecting the big stuff.
• 38:55
  Speaker 1: So in order to keep the quantum mechanical effects relevant,
• 38:58
  Speaker 1: you've got to keep it like really really small. And
• 39:01
  Speaker 1: so what happens when you try to do that, when
• 39:03
  Speaker 1: you add enough stuff together so that it stays quantum
• 39:06
  Speaker 1: mechanical and gravity starts to get relevant, you get a
• 39:09
  Speaker 1: black hole. That's what a black hole is is a
• 39:12
  Speaker 1: huge amount of mass in a tiny little space. And so,
• 39:16
  Speaker 1: on one hand, that's exciting, Wow, the answer is inside
• 39:19
  Speaker 1: a black hole. On the other hand, all that's really frustrating.
• 39:22
  Speaker 1: The answer is hidden inside a black hole. We can't
• 39:26
  Speaker 1: see it. We think that probably inside a black hole
• 39:28
  Speaker 1: is evidence that would point us in the direction of
• 39:31
  Speaker 1: how to bring these two theories together, how to explain
• 39:34
  Speaker 1: what happens when you have a bunch of quantum stuff
• 39:37
  Speaker 1: that has enough gravity that you can't ignore it anymore.
• 39:40
  Speaker 3: It feels like a sick joke, right to put all
• 39:42
  Speaker 3: the answers inside a thing that we can't see inside,
• 39:47
  Speaker 3: and if we tried to get someone in there, it
• 39:50
  Speaker 3: would destroy them.
• 39:53
  Speaker 1: Exactly, and they might actually survive going inside the black
• 39:56
  Speaker 1: hole and seeing the answer, But then they could never
• 39:58
  Speaker 1: tell us even come collect their Nobel prize. We'd have
• 40:02
  Speaker 1: to send in the Nobel Prize after them, assuming that
• 40:05
  Speaker 1: they'd figured it out.
• 40:06
  Speaker 3: Like I feel like, if someone dives into a black hole,
• 40:08
  Speaker 3: they just deserve a Nobel Prize, whether they discover.
• 40:11
  Speaker 2: Anything or not.
• 40:13
  Speaker 3: But we can study black holes, we just can't like
• 40:16
  Speaker 3: see inside them. So is there any way to study
• 40:21
  Speaker 3: a black hole such that it gives us any clues
• 40:24
  Speaker 3: about this?
• 40:25
  Speaker 1: Well, there is one possible crack in the veneer of
• 40:29
  Speaker 1: black holes, which is their hawking radiation. Black holes are
• 40:32
  Speaker 1: not totally black. They do emit some radiation. It's even
• 40:36
  Speaker 1: talking to the calculation a few decades ago, and he
• 40:38
  Speaker 1: didn't have a theory for what is the gravity of particles,
• 40:42
  Speaker 1: but he did some sort of like clever handwavey approximations,
• 40:45
  Speaker 1: and he showed that if you have a quantum field
• 40:48
  Speaker 1: near something with an event horizon, then there has to
• 40:51
  Speaker 1: be radiation leaving the event horizon. So now we interpret
• 40:55
  Speaker 1: this as like the black hole is evaporating, it's like
• 40:57
  Speaker 1: giving up some of its energy. The idea is that
• 41:00
  Speaker 1: maybe in that radiation, maybe as particles are being generated
• 41:03
  Speaker 1: by the event horizon, there might be clues as to
• 41:06
  Speaker 1: what's inside the black hole. It's sort of very speculative,
• 41:09
  Speaker 1: cutting edge research, but it's possible that if we did
• 41:13
  Speaker 1: see hawking radiation, we could maybe infer from it something
• 41:17
  Speaker 1: about what's inside the black hole. But hawking radiation would
• 41:20
  Speaker 1: be very very faint, and black holes are very very
• 41:23
  Speaker 1: far away and hidden by all sorts of other, very
• 41:26
  Speaker 1: noisy stuff like hot gases emitting all sorts of radiation.
• 41:30
  Speaker 1: So we've never seen hawking radiation, and frankly, we don't
• 41:33
  Speaker 1: seem very likely to anytime in the near future. So
• 41:36
  Speaker 1: until then, the only frontier really is mental. Can we
• 41:40
  Speaker 1: come up with a new theory that brings these two
• 41:42
  Speaker 1: things together that reconciles the uncertainty of quantum mechanics and
• 41:46
  Speaker 1: the determinism of relativity.
• 41:49
  Speaker 2: Well, give me like three minutes while ads play, and
• 41:52
  Speaker 2: I'll try to come up with something.
• 41:54
  Speaker 1: All right, The Katie Golden tries to win the Nobel
• 41:56
  Speaker 1: Prize in three minutes challenge.
• 41:58
  Speaker 2: Go all right, I think I've got it, Daniel.
• 42:13
  Speaker 1: Oh wow, I'm so desperate to hear what you came
• 42:15
  Speaker 1: up with.
• 42:15
  Speaker 3: Did you guys remember to carry the one.
• 42:20
  Speaker 1: Hold on a second? Did we miss a minus science?
• 42:23
  Speaker 1: Is that the whole problem? Oh my gosh, Katie, pause
• 42:26
  Speaker 1: this recording right now to rush off to Sweden to
• 42:29
  Speaker 1: collecting about rice.
• 42:31
  Speaker 3: Well you're very welcome, but yes, let's talk about how
• 42:35
  Speaker 3: to go from like our observational science to bringing it
• 42:41
  Speaker 3: into the brain. How could we possibly do science from
• 42:46
  Speaker 3: inside our own heads?
• 42:49
  Speaker 1: Well, sometimes it comes down to just being creative. You
• 42:51
  Speaker 1: know a lot of big advances in human history have
• 42:55
  Speaker 1: come from just people sitting in their dank study thinking
• 42:58
  Speaker 1: about the nature of the universe and pulling ideas together.
• 43:01
  Speaker 1: You know, Einstein's revolution with a photoelectric effect. He didn't
• 43:05
  Speaker 1: do that experiment. He didn't have a piece of metal
• 43:07
  Speaker 1: and a bright light in his laboratory. Guy didn't have
• 43:10
  Speaker 1: a laboratory. He read a paper or somebody else did
• 43:13
  Speaker 1: this experiment, and he just thought about it and had
• 43:15
  Speaker 1: this idea for how to explain it and combined it
• 43:18
  Speaker 1: with something he heard from Max Plank about how to
• 43:21
  Speaker 1: explain how stuff glows and the temperature at which things glow.
• 43:25
  Speaker 1: And decades earlier, Maxwell brought together electricity and magnetism just
• 43:29
  Speaker 1: by writing them down nicely on a sheet of paper
• 43:32
  Speaker 1: and noticing that there were symmetries between them. So we
• 43:34
  Speaker 1: can make a lot of progress in physics just by
• 43:37
  Speaker 1: having new ideas.
• 43:38
  Speaker 3: So are there people in dank rooms I imagine them
• 43:44
  Speaker 3: with like maybe one light bulb lighting the entire room,
• 43:47
  Speaker 3: hard at work trying to figure this out. Has there
• 43:50
  Speaker 3: been any progress made on trying to come up with
• 43:53
  Speaker 3: a philosophical or mathematical explanation.
• 43:56
  Speaker 1: So people have been working on this for a long time,
• 43:58
  Speaker 1: and it's very challenging. Mathematically. It's hard to see how
• 44:02
  Speaker 1: you can get this sort of uncertainty of quantum mechanics
• 44:05
  Speaker 1: and the rigor and determination of general relativity to play
• 44:10
  Speaker 1: nicely together. There's been a lot of attempts, and a
• 44:13
  Speaker 1: lot of them have failed. But there is a new
• 44:14
  Speaker 1: idea out there, and that's quantum relativity what we're talking
• 44:18
  Speaker 1: about today, and the idea is instead of taking general
• 44:21
  Speaker 1: relativity and trying to change it so that it's like uncertain,
• 44:25
  Speaker 1: rather than saying maybe the curvature or space time is
• 44:28
  Speaker 1: uncertain in the way we're talking about earlier, it's wondering
• 44:31
  Speaker 1: can we actually see how quantum mechanics comes naturally from relativity,
• 44:36
  Speaker 1: Like maybe the weirdness of quantum mechanics just emerges from
• 44:40
  Speaker 1: relativity itself, the way the ideal gas law emerges from
• 44:44
  Speaker 1: the motion of particles, or hurricanes emerge from the swirling
• 44:48
  Speaker 1: of droplets in the atmosphere. Is it possible to find
• 44:51
  Speaker 1: hints in relativity from which we could build the weirdness
• 44:55
  Speaker 1: of quantum mechanics directly. That's why it's called quantum relativity.
• 45:00
  Speaker 1: Take relativity and find a way to build quantum mechanics
• 45:03
  Speaker 1: on top of it, rather than like jamming quantum uncertainty
• 45:06
  Speaker 1: directly into relativity.
• 45:08
  Speaker 3: That's interesting because I think of when I think of
• 45:11
  Speaker 3: sort of the direction of causality, I think of, like
• 45:15
  Speaker 3: the small things cause the big things to happen, right,
• 45:19
  Speaker 3: the little particles there's some causality of like the small
• 45:23
  Speaker 3: particles that make up the big things, you know, cause
• 45:26
  Speaker 3: some effect, so that I would always kind of intuitively
• 45:29
  Speaker 3: think like, well, we have to figure out how the
• 45:31
  Speaker 3: small things behavior explains the big things. But it seems
• 45:35
  Speaker 3: like this is more like you're taking the kind of
• 45:38
  Speaker 3: behavior of big things with general relativity and seeing how
• 45:43
  Speaker 3: that could either explain or how you could see quantum
• 45:49
  Speaker 3: mechanics grow out of that.
• 45:51
  Speaker 1: Yeah, exactly, and so let's drill in on some of
• 45:53
  Speaker 1: the details to make this a little bit more concrete.
• 45:56
  Speaker 2: You know.
• 45:56
  Speaker 1: One of the crucial things we have in quantum mechanics
• 45:59
  Speaker 1: that we don't have in relativity is this uncertainty, this
• 46:03
  Speaker 1: possibility for things to be in two locations. Right, a particle,
• 46:07
  Speaker 1: for example, we say maybe it does this and maybe
• 46:09
  Speaker 1: it does that, and we said, that's uncertain It has
• 46:11
  Speaker 1: both possibilities, whereas in relativity we have a lot of determination.
• 46:16
  Speaker 1: Like you shoot a particle, even if it's near the
• 46:18
  Speaker 1: speed of light, it's going in some direction, you know
• 46:20
  Speaker 1: what it's going to do. You can calculate it. One
• 46:22
  Speaker 1: of the core conflicts between these two theories is just that.
• 46:25
  Speaker 1: So the authors of this theory quantum relativity have found
• 46:29
  Speaker 1: a way to try to find multiple possibilities in relativity.
• 46:33
  Speaker 1: They say, hmm, maybe there's some overlooked mathematics that shows
• 46:37
  Speaker 1: us how relativity actually can have like multiple solutions simultaneously.
• 46:43
  Speaker 1: One of the founding principles of relativity is that light
• 46:45
  Speaker 1: always moves at the speed of light. Right, all observers
• 46:48
  Speaker 1: see light moving at the speed of light, no matter
• 46:50
  Speaker 1: how fast you're going. So you're moving in half the
• 46:53
  Speaker 1: speed of light relative to the Earth. You turn on
• 46:56
  Speaker 1: a flashlight, you're going to see that light being moving
• 46:58
  Speaker 1: at the speed of light relative you. Somebody on the
• 47:01
  Speaker 1: ground who sees you moving at half the speed of
• 47:04
  Speaker 1: light and turning on your flashlight, they look at that
• 47:06
  Speaker 1: light beam, they also see it moving at the speed
• 47:09
  Speaker 1: of light. They don't see it moving at the speed
• 47:11
  Speaker 1: of light plus half the speed of light. It's one
• 47:13
  Speaker 1: of the really weird things about special relativity.
• 47:16
  Speaker 3: Right, so light there is a constant speed of light
• 47:21
  Speaker 3: that can't really be slowed down or sped up exactly.
• 47:24
  Speaker 1: And this is the founding assumption of special relativity, at
• 47:27
  Speaker 1: least to a whole bunch of mathematics. It tells us
• 47:29
  Speaker 1: how to see things from different perspectives. Tells us like,
• 47:32
  Speaker 1: how is it possible to see light moving at this
• 47:35
  Speaker 1: speed for this observer and seeing it move at the
• 47:37
  Speaker 1: same speed for that observer. It helps us tie it
• 47:39
  Speaker 1: all together, tells a different story for how the universe works,
• 47:43
  Speaker 1: and time goes weird sometimes and things get short, and
• 47:46
  Speaker 1: we have podcasts digging into all those details. But it
• 47:48
  Speaker 1: gives us this picture of like how different people can
• 47:51
  Speaker 1: see the universe from different velocities, and this is called
• 47:54
  Speaker 1: the Lorentz transforms. It tells you how to transform between
• 47:57
  Speaker 1: one observer and another observer. Because it turns out to
• 48:00
  Speaker 1: not as simple as we thought.
• 48:01
  Speaker 3: Yeah, I'm looking at this formula and doesn't look super
• 48:04
  Speaker 3: simple to me.
• 48:06
  Speaker 1: No, it's not simple, and it's nonlinear, and it's got
• 48:08
  Speaker 1: square roots in it, and it gets really wonky, which
• 48:10
  Speaker 1: is why relativity is so weird and time flows strangely
• 48:13
  Speaker 1: and you have the twin paradox and all that stuff. Now,
• 48:15
  Speaker 1: that's fine, But it turns out there's actually a second solution.
• 48:19
  Speaker 1: There's another way you could describe the transformation how people
• 48:23
  Speaker 1: see things in different velocities. That also satisfies this requirement
• 48:28
  Speaker 1: that the speed of light is the same for everybody,
• 48:30
  Speaker 1: sort of like a second solution to an equation. You know,
• 48:33
  Speaker 1: if you have like X squared equals nine, one solution is, oh,
• 48:37
  Speaker 1: X equals three. Another solution is what if X equals
• 48:40
  Speaker 1: minus three. This is the kind of thing that crops
• 48:42
  Speaker 1: up all the time in mathematics and sometimes in physics,
• 48:45
  Speaker 1: we like, well, minus three doesn't make sense. We'll just
• 48:48
  Speaker 1: ignore that. We'll just drop the unphysical solution.
• 48:51
  Speaker 3: Yeah, you can't have negative three apples, missus Birch.
• 48:56
  Speaker 1: You can actually go into debt for apples, and you
• 48:58
  Speaker 1: can be an apple or prison. So yeah, thanks financial
• 49:01
  Speaker 1: engineers for inventing negative money.
• 49:03
  Speaker 3: I forgot that our currency was based on the Apple standard.
• 49:09
  Speaker 1: Exactly. So in this scenario, there's one solution to these
• 49:12
  Speaker 1: transformations to tell you, like how different observers see the
• 49:15
  Speaker 1: universe different velocities, And that's the one that assumes that
• 49:18
  Speaker 1: everything travels at the speed of light or less. It's
• 49:21
  Speaker 1: actually a second solution, a second way to transform between
• 49:25
  Speaker 1: these frames that holds for velocities greater than the speed
• 49:29
  Speaker 1: of light. And that's like, what, hold on a second,
• 49:31
  Speaker 1: I thought the whole assumption of special relativity was that
• 49:34
  Speaker 1: you can only move slower than the speed of light, right,
• 49:38
  Speaker 1: That is one way to interpret these transformations. There's another
• 49:42
  Speaker 1: way to interpret them for velocities greater than the speed
• 49:45
  Speaker 1: of light. So these would mean particles moving faster than
• 49:49
  Speaker 1: the speed of light.
• 49:51
  Speaker 2: What kind of particles are these? Do we know?
• 49:53
  Speaker 1: So there's a theory about particles moving faster than the
• 49:56
  Speaker 1: speed of light. They're called tachyons, and they do satisfy
• 50:00
  Speaker 1: the mathematics of relativity, though nobody's ever seen one. One
• 50:03
  Speaker 1: problem with anything moving faster than the speed of light
• 50:06
  Speaker 1: is that you can end up with tricky paradoxes about
• 50:09
  Speaker 1: the order of things and causality, because remember that observers
• 50:12
  Speaker 1: moving at high speeds can see stuff happening at different times.
• 50:16
  Speaker 1: Like if I see event A happening before event B,
• 50:19
  Speaker 1: you might see the opposite order of stuff because you're
• 50:21
  Speaker 1: flying by me at a high speed. That's one of
• 50:24
  Speaker 1: the consequences of special relativity that you're not guaranteed simultaneity
• 50:28
  Speaker 1: for all frames. That different observers can see the order
• 50:31
  Speaker 1: of events differently, and that's usually fine, it's not a
• 50:34
  Speaker 1: big deal. But if you can move faster than the
• 50:36
  Speaker 1: speed of light, then you start to see things that
• 50:38
  Speaker 1: are causally linked be reversed. Like, for example, if I
• 50:42
  Speaker 1: fire an arrow, then somebody moving past me is faster
• 50:46
  Speaker 1: than the speed of light could see the arrow hit
• 50:48
  Speaker 1: the apple before I even fire it. That seems sort
• 50:51
  Speaker 1: of problematic, and people are like, yeah, let's just cross
• 50:53
  Speaker 1: that off and say that doesn't happen, but actually opens
• 50:56
  Speaker 1: the door and exactly the way we might need to
• 50:58
  Speaker 1: link relativity with quantum mechanics, because now we have like
• 51:03
  Speaker 1: two explanations for those events, like does Daniel fire the
• 51:06
  Speaker 1: arrow before it hits the apple or does it hit
• 51:08
  Speaker 1: the apple before I fire the arrow? So the idea
• 51:11
  Speaker 1: of quantum relativity is to say, well, what if you
• 51:14
  Speaker 1: look at these things both from the less than the
• 51:16
  Speaker 1: speed of light perspective and the greater than the speed
• 51:20
  Speaker 1: of life perspective, Like if you allow both views of it,
• 51:23
  Speaker 1: then you have sort of like two different ideas for
• 51:26
  Speaker 1: what might be happening here, and there isn't a deterministic
• 51:29
  Speaker 1: explanation for which is the right one.
• 51:32
  Speaker 3: I mean, you had mentioned earlier that this was kind
• 51:34
  Speaker 3: of dismissed, right, because like the idea is that you
• 51:38
  Speaker 3: can't observe causally linked events in reverse. What is the
• 51:43
  Speaker 3: assumption behind that that says that you can't do that?
• 51:46
  Speaker 2: Because like, I.
• 51:47
  Speaker 3: Know, it sounds obvious, right, like, of course you can't.
• 51:49
  Speaker 3: I would assume there's actually some kind of law in
• 51:52
  Speaker 3: physics that does link to that, because you know what
• 51:56
  Speaker 3: we know about like assumptions, like we have all sorts
• 51:58
  Speaker 3: of assumptions about the world works because that's how we
• 52:00
  Speaker 3: observe it. We as humans never observe things in reverse.
• 52:04
  Speaker 3: But is there an actual law in either physics or
• 52:08
  Speaker 3: general relativity that would prohibit that observation from coming before
• 52:13
  Speaker 3: the event?
• 52:13
  Speaker 1: Yeah, that's a great question. Why do we assume that
• 52:16
  Speaker 1: there's causality in the universe, that things have to be linked?
• 52:19
  Speaker 1: And it's just sort of like part of how we
• 52:21
  Speaker 1: think about physics. It's a core assumption we make. We
• 52:24
  Speaker 1: don't know that it's true, but it sort of makes
• 52:27
  Speaker 1: sense to us, and so we try to hold on
• 52:29
  Speaker 1: to it as long as possible, build theories on that
• 52:31
  Speaker 1: assumption and see if they work. But it might be
• 52:34
  Speaker 1: that we have to give it up. There are other
• 52:36
  Speaker 1: hints in other theories of physics, sort of the cutting edge,
• 52:39
  Speaker 1: that maybe causality isn't the fundamental aspect of the universe.
• 52:43
  Speaker 1: It might be something we are trying to impose on it.
• 52:46
  Speaker 1: You know, think about the way that we explain the universe.
• 52:48
  Speaker 1: We tend to tell stories. Stories are like little causal links.
• 52:53
  Speaker 1: I did this, and then she did that, and then
• 52:55
  Speaker 1: this happened. It's like A, then B and C, then D.
• 52:58
  Speaker 1: It's sort of embedded deeply in how we think. It
• 53:01
  Speaker 1: doesn't mean it has to be embedded deeply into the universe.
• 53:04
  Speaker 1: And so this is sort of like giving up that
• 53:06
  Speaker 1: causal chain and saying, well, maybe A cause B, but
• 53:10
  Speaker 1: maybe B caused A. And that's where you get your
• 53:13
  Speaker 1: crack indeterminism In relativity, it says, maybe there are two
• 53:17
  Speaker 1: ways to view these events. One subliminal, sorry, one subluminal,
• 53:22
  Speaker 1: not subliminal as in slower than the speed.
• 53:25
  Speaker 3: Of lfemptoms about the superliminal messaging, yeah.
• 53:30
  Speaker 1: And one super illuminal, like a view from an observer
• 53:33
  Speaker 1: moving fast than the speed of light that sees an
• 53:35
  Speaker 1: opposite order of events. And this is basically the crack
• 53:39
  Speaker 1: that this whole theory of quantum relativity is built on.
• 53:42
  Speaker 1: It says, within relativity, maybe you can have nondeterminism, because
• 53:47
  Speaker 1: maybe the superluminal view of the universe is different from
• 53:51
  Speaker 1: the subluminal view, that the order of events can be different.
• 53:55
  Speaker 1: From within relativity, we now see a little bit of uncertainty,
• 53:59
  Speaker 1: a loss of de herminism, and that's basically the starting
• 54:02
  Speaker 1: place for quantum relativity.
• 54:04
  Speaker 3: I think we have to remind ourselves that physicists are
• 54:07
  Speaker 3: human beings and they have the same kind of mental fallacies,
• 54:14
  Speaker 3: or not necessarily fallacies, but just habits the routine that
• 54:18
  Speaker 3: all humans have, which is viewing things in terms of
• 54:23
  Speaker 3: what we have adapted to as human beings or earlier
• 54:28
  Speaker 3: as primates, and it's such a strong thing. There have
• 54:32
  Speaker 3: been studies on people's behavior where when you look at
• 54:36
  Speaker 3: like a screen that has like randomly moving dots on
• 54:40
  Speaker 3: a screen or something like, people will try to impose
• 54:44
  Speaker 3: some kind of like rules on this or like volition
• 54:48
  Speaker 3: to these things, like that these feel alive because they're
• 54:51
  Speaker 3: moving randomly, and so you think, well, then there must
• 54:54
  Speaker 3: be some kind of autonomy of these things, like some
• 54:58
  Speaker 3: reason that it's doing is so like this causality link,
• 55:01
  Speaker 3: like I mentioned earlier. It's even found in like babies,
• 55:05
  Speaker 3: where you'll see, like if they see something that defies
• 55:08
  Speaker 3: the laws of very simple physics of like a ball
• 55:11
  Speaker 3: hitting a ball and that ball kind of moving, they
• 55:15
  Speaker 3: stare at that because.
• 55:16
  Speaker 2: That's not what they're expecting.
• 55:17
  Speaker 3: So it seems like a huge challenge to overcome our
• 55:22
  Speaker 3: humanness when we're also trying to answer these questions about
• 55:27
  Speaker 3: the universe that do not necessarily play by the same
• 55:31
  Speaker 3: rules as say, like a primate that has somehow gotten
• 55:36
  Speaker 3: smart enough to start writing down numbers.
• 55:39
  Speaker 1: Yeah, and we've often seen the appearance of autonomy and
• 55:43
  Speaker 1: action in the universe, you know, explaining whether in terms
• 55:47
  Speaker 1: of some big guy in the sky throwing thunderbolts, et cetera,
• 55:49
  Speaker 1: et cetera. And so we do have to be careful
• 55:52
  Speaker 1: and question our assumptions. And sometimes when we are failing
• 55:55
  Speaker 1: to describe the universe that we see, we need to
• 55:58
  Speaker 1: circle back and say, well, maybe there's something wrong in
• 56:01
  Speaker 1: the foundations of our science itself. Maybe we need to
• 56:04
  Speaker 1: be asking questions about whether all of these assumptions really
• 56:07
  Speaker 1: hold and what breaks if we get rid of them,
• 56:10
  Speaker 1: or what breakthroughs we might be able to make.
• 56:12
  Speaker 3: So, once we get rid of this assumption that there
• 56:16
  Speaker 3: has to be this causality, has there been any breakthroughs
• 56:20
  Speaker 3: in terms of then connecting this potential new model of
• 56:24
  Speaker 3: general relativity to quantum mechanics, Like, have there been successful
• 56:29
  Speaker 3: sort of developments in quantum relativity beyond? Just like maybe
• 56:33
  Speaker 3: we can issue the causality.
• 56:36
  Speaker 1: Not yet. It's sort of like a promising direction for
• 56:39
  Speaker 1: people to build on. What it has generated is a
• 56:41
  Speaker 1: whole series of papers arguing about it. So a bunch
• 56:44
  Speaker 1: of physicis are like, hey, you can't do that. This
• 56:46
  Speaker 1: doesn't make sense, and other people be like, no, actually,
• 56:49
  Speaker 1: maybe it does. And so, you know, it's a healthy conversation.
• 56:52
  Speaker 1: So far hasn't led anywhere concrete yet, but you know,
• 56:56
  Speaker 1: it might be that we look back in one hundred
• 56:58
  Speaker 1: years and tell stories about this moment where people are like,
• 57:01
  Speaker 1: wait a second, what about this basic assumption, or this
• 57:04
  Speaker 1: could just end up on the very very deep trash
• 57:08
  Speaker 1: can of the theories that have attempted to unify general
• 57:11
  Speaker 1: relativity and quantum mechanics and failed.
• 57:14
  Speaker 3: I mean, you need to fill a few trash cans
• 57:17
  Speaker 3: full of crumpled up sheets to make a physics aline,
• 57:20
  Speaker 3: as I understand it.
• 57:23
  Speaker 1: Exactly. But it's fun to examine all these assumptions to
• 57:26
  Speaker 1: try to explain our universe in terms of the tiniest
• 57:29
  Speaker 1: little particles, and to try to unify those theories, the
• 57:32
  Speaker 1: ones that describe the really big, heavy stuff and the
• 57:35
  Speaker 1: ones that describe the tiniest little particles flitting around inside
• 57:39
  Speaker 1: our atoms. Maybe one day we'll figure it out. Until then,
• 57:42
  Speaker 1: thanks very much Kinnie for joining me on this journey
• 57:45
  Speaker 1: to our lack of understanding about the universe.
• 57:48
  Speaker 3: Thanks for having me, and really do check on whether
• 57:50
  Speaker 3: you guys just forgot to carry the one, because you know,
• 57:53
  Speaker 3: we all make mistakes.
• 57:55
  Speaker 1: I'm on it, and if it turns out you were right,
• 57:57
  Speaker 1: we'll definitely cite you. Thanks everyone for listening, See you
• 58:01
  Speaker 1: next time. For more science and curiosity, come find us
• 58:08
  Speaker 1: on social media, where we answer questions and post videos.
• 58:12
  Speaker 1: We're on Twitter, disc Org, Insta, and now TikTok. Thanks
• 58:16
  Speaker 1: for listening and remember that Daniel and Jorge Explain the
• 58:18
  Speaker 1: Universe is a production of iHeartRadio. For more podcasts from iHeartRadio,
• 58:23
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• 58:27
  Speaker 1: to your favorite shows.