Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 51

Transcript

Listener Questions 51 · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, have you been watching the latest Marvel movies
• 0:10
  Speaker 1: and TV shows?
• 0:12
  Speaker 2: Hmmm, I hope you're not going to ask me about
• 0:13
  Speaker 2: the physics of it. Oh.
• 0:15
  Speaker 1: I wasn't going to ask you about time travel and Loki. Mm.
• 0:18
  Speaker 2: But now you're not well.
• 0:20
  Speaker 1: Here in your reaction. I think I have to travel
• 0:22
  Speaker 1: back in time now and maybe think of another question.
• 0:25
  Speaker 2: See, that's the problem. If you had done that, we'd
• 0:27
  Speaker 2: never be having this conversation.
• 0:29
  Speaker 1: Oh well, maybe it depends on which branch of the
• 0:32
  Speaker 1: timeline we're on.
• 0:33
  Speaker 2: No, my god, there are no branches too timelines. Oh
• 0:37
  Speaker 2: my gosh.
• 0:38
  Speaker 1: Or maybe I did go back in time and this
• 0:40
  Speaker 1: is a better outcome than the one that I originally
• 0:44
  Speaker 1: pitched to you. This might be the best timeline where
• 0:47
  Speaker 1: that could be.
• 0:49
  Speaker 2: Then I'm disappointed in the multiverse.
• 0:51
  Speaker 1: Maybe you just don't know how much worse it could be.
• 0:53
  Speaker 2: If this is the best it gets, then it must
• 0:55
  Speaker 2: get pretty bad.
• 1:00
  Speaker 1: It's like you maybe need to switch to the DC universe.
• 1:17
  Speaker 3: Hi.
• 1:17
  Speaker 1: I'm Jorge Made, cartoonist and the author of Oliver's Great
• 1:20
  Speaker 1: Big Universe.
• 1:21
  Speaker 2: Hi I'm Daniel. I'm a particle physicist and a professor
• 1:24
  Speaker 2: at UC Irvine and I can mostly read science fiction
• 1:27
  Speaker 2: without being grumpy mostly.
• 1:29
  Speaker 1: What percentage would you say is your grumpiness level when
• 1:32
  Speaker 1: you're reading science fiction.
• 1:34
  Speaker 2: There is a spot on the wall across the bedroom
• 1:37
  Speaker 2: where the books usually land when I throw them in frustration.
• 1:41
  Speaker 1: I'll just say that there's a dent there, more like.
• 1:45
  Speaker 2: A mark, but yeah, there's a physical impression left.
• 1:48
  Speaker 1: Have you actually thrown a book?
• 1:50
  Speaker 2: Oh many?
• 1:50
  Speaker 1: Yes, no way. Wow, that's a strong reaction.
• 1:54
  Speaker 2: It's just so disappointing when they set you up for something,
• 1:56
  Speaker 2: they have some interesting ideas, and then they can't even
• 1:59
  Speaker 2: be consistent, or they just write stuff that doesn't make sense.
• 2:02
  Speaker 2: It's just frustrating because it makes me think about what
• 2:05
  Speaker 2: it could have been.
• 2:06
  Speaker 1: Oh man, But you're not angry at the physics, because
• 2:09
  Speaker 1: I imagine the physics is all made up in science
• 2:11
  Speaker 1: fiction to some degree. You're more frustrated with the storytelling
• 2:16
  Speaker 1: or the logic of the story.
• 2:17
  Speaker 2: Well, it's all tied together, right, of course, the physics
• 2:20
  Speaker 2: is made up. It's science fiction. After all. They can
• 2:22
  Speaker 2: have fictional science, but it's still science. They got to
• 2:25
  Speaker 2: stick to it. If they're going to tell a story,
• 2:27
  Speaker 2: they got to follow the rules. Otherwise, if there are
• 2:29
  Speaker 2: no rules. It's hardly an interesting story.
• 2:32
  Speaker 1: Now, after you throw the book, do you go and
• 2:34
  Speaker 1: pick it up and finish it anyways or do you
• 2:37
  Speaker 1: leave it there on the pile?
• 2:38
  Speaker 2: It depends on what's on the top of the two
• 2:40
  Speaker 2: read pile.
• 2:41
  Speaker 1: I suppose you're not like a complete is like some
• 2:44
  Speaker 1: people when they start a book, they have to finish it.
• 2:46
  Speaker 2: Oh no, I don't finish most books.
• 2:48
  Speaker 1: Oh interesting. Have you ever thrown a podcast at the wall?
• 2:55
  Speaker 2: No, I've never thrown podcasts at the wall. I've just
• 2:58
  Speaker 2: paused them.
• 3:00
  Speaker 1: Although it does feel like this podcast is just us
• 3:02
  Speaker 1: throwing things in the wall to see what sticks.
• 3:05
  Speaker 2: No, this is us trying to explain physics to everybody
• 3:08
  Speaker 2: out there listening.
• 3:09
  Speaker 1: Well anyways, Welcome to our podcast, Daniel and Jorge Explain
• 3:11
  Speaker 1: the Universe, a production of iHeartRadio.
• 3:14
  Speaker 2: Where we do our best not to frustrate you into
• 3:17
  Speaker 2: throwing your phone or computer or car across the wall,
• 3:21
  Speaker 2: whatever device you're using to listen to us. We want
• 3:24
  Speaker 2: to take you on a tour of everything that we
• 3:25
  Speaker 2: understand in the universe and everything that we don't. We
• 3:28
  Speaker 2: want to explain to you our vision of how the
• 3:30
  Speaker 2: universe works from the tiniest little, itty bitty bits, all
• 3:33
  Speaker 2: the way up to the biggest monster black holes. We
• 3:36
  Speaker 2: think the universe does make sense, can be made sense of,
• 3:40
  Speaker 2: and we want desperately to explain all of it to you.
• 3:42
  Speaker 1: That's right. The universe we live in is not science fiction.
• 3:45
  Speaker 1: It is science period science reality, and so we all
• 3:50
  Speaker 1: have questions about how it works while we're here and
• 3:53
  Speaker 1: what happens when you throw a bunch of books at
• 3:55
  Speaker 1: a wall.
• 3:56
  Speaker 2: Science reality. I like how you just renamed the whole
• 3:59
  Speaker 2: nonfiction job. It's a better name, though.
• 4:03
  Speaker 1: Yeah, science reality. There you go. Well, they have like
• 4:06
  Speaker 1: reality TV, why not have reality science?
• 4:09
  Speaker 2: Yeah? I don't want to be lumped in with reality TV. Actually, hey,
• 4:15
  Speaker 2: the problem with nonfiction is you're defining it by what
• 4:17
  Speaker 2: it isn't instead of what it is. Right.
• 4:19
  Speaker 1: Oh yeah, yeah, nobody wants to be a non anything.
• 4:23
  Speaker 2: I don't not want to be that.
• 4:25
  Speaker 1: You don't want to be a nonconformist. Science trail blazing,
• 4:29
  Speaker 1: that's your job, basically. How about reality trail blazing.
• 4:32
  Speaker 2: Exploring the dense underbrush of reality, hacking our way through
• 4:35
  Speaker 2: the jungles of truth.
• 4:37
  Speaker 1: Yeah, that could be a nice show, like on Netflix,
• 4:39
  Speaker 1: like Big science where you put a bunch of physicists
• 4:41
  Speaker 1: in one house with a large particle collider and you
• 4:44
  Speaker 1: see what happens every week They have to vote a
• 4:46
  Speaker 1: physicists off.
• 4:48
  Speaker 2: Or maybe they have to vote a physicist into the collider.
• 4:51
  Speaker 1: Oh my goodness. That is both good and horrifying.
• 4:56
  Speaker 2: Probably good TV. Yeah, yeah, yeah.
• 4:58
  Speaker 1: It's like squid games exactly, h squid physics games, science game,
• 5:03
  Speaker 1: science games. Yeah, there you go, particle games.
• 5:07
  Speaker 2: But science isn't just a game. It's a serious effort
• 5:09
  Speaker 2: to understand the universe, and that's what we try to
• 5:12
  Speaker 2: do in our jobs. We try to do on this podcast,
• 5:14
  Speaker 2: and we also encourage you to do because you can
• 5:18
  Speaker 2: also pick up a machete and help us hack through
• 5:20
  Speaker 2: the jungles of truth to understand the universe just by
• 5:23
  Speaker 2: thinking like a physicist, which means just being curious and
• 5:26
  Speaker 2: not settling for not understanding. There's too many knots there, huh.
• 5:30
  Speaker 2: I should define it in terms of positives demanding sufficient explanations.
• 5:35
  Speaker 2: And when you don't understand something about the universe, we
• 5:37
  Speaker 2: want you to write into us share your question because
• 5:40
  Speaker 2: probably somebody else out there has the same thought.
• 5:44
  Speaker 1: I don't know if that was better. I'm a little
• 5:46
  Speaker 1: nonplussed about it.
• 5:48
  Speaker 2: I'm pretty plussed.
• 5:51
  Speaker 1: Well, let's plus it, let's plus it some more.
• 5:52
  Speaker 2: I might even be multiplied it. But I don't want
• 5:55
  Speaker 2: to divide us over it.
• 5:57
  Speaker 1: But yeah, science is a game, and it all starts
• 5:59
  Speaker 1: with questions. The whole journey of sign starts with looking
• 6:03
  Speaker 1: at the world around as I'm wondering, why is it
• 6:05
  Speaker 1: like that? How does it work? And what would happen
• 6:08
  Speaker 1: if I throw this at the wall.
• 6:09
  Speaker 2: So you can either throw that thing at the wall,
• 6:11
  Speaker 2: or you can just write to us with your question
• 6:13
  Speaker 2: and we'll do our best to answer it. We answer
• 6:15
  Speaker 2: every question we get from listeners. Just write to us
• 6:17
  Speaker 2: to questions at Danielandjorge dot com. And some of the
• 6:21
  Speaker 2: questions we think other people might want to hear the
• 6:23
  Speaker 2: answers to, and so we select them to answer on
• 6:26
  Speaker 2: the podcast.
• 6:27
  Speaker 1: So today on the podcast, we'll be tackling listener questions
• 6:36
  Speaker 1: number fifty one, Oh boy, listener questions in that over
• 6:39
  Speaker 1: middle eight.
• 6:40
  Speaker 2: That's right, we're rounding up to one hundred now it's
• 6:42
  Speaker 2: fifty plus. We're going to get senior citizen discounts pretty soon,
• 6:46
  Speaker 2: starting dinner at three pm that's right.
• 6:49
  Speaker 1: Yeah, yeah, the discounts oh man, does that mean we
• 6:52
  Speaker 1: have to give shorter answers.
• 6:55
  Speaker 2: I'm not going to offend our senior listeners by suggesting
• 6:59
  Speaker 2: that they can't comprehend long complex answers.
• 7:01
  Speaker 1: No, I'm just saying, you know, your appetite goes down
• 7:05
  Speaker 1: as you age.
• 7:06
  Speaker 2: Oh, I see smaller meals. I don't know what I'm saying,
• 7:10
  Speaker 2: more top us, maybe more top us.
• 7:12
  Speaker 1: Yeah, there you go, more variety, because let's face it,
• 7:15
  Speaker 1: the time is running out for those of us.
• 7:17
  Speaker 2: Over fifty, unless you live near the vicinity of a
• 7:21
  Speaker 2: black hole, in which case time is slowing down for
• 7:23
  Speaker 2: others but not for you. Yeah, but relatively for you.
• 7:25
  Speaker 2: You see everybody else living really fast.
• 7:27
  Speaker 1: Well, let's try to get through these questions as fast
• 7:30
  Speaker 1: as we can then.
• 7:30
  Speaker 2: And the first one is actually about time. Yeah.
• 7:32
  Speaker 1: Yeah, we have some awesome questions here today about the
• 7:36
  Speaker 1: speed of light near a black hole, about quantum entanglement,
• 7:40
  Speaker 1: and also about possible time travel. Pretty awesome questions from people, Daniel.
• 7:46
  Speaker 1: Do these questions make you smile when you get them?
• 7:48
  Speaker 2: All the questions make me smile. I love that ding
• 7:50
  Speaker 2: when I get a question in the listener inbox and
• 7:52
  Speaker 2: lets me take a break from whatever else I'm doing
• 7:54
  Speaker 2: and think about physics.
• 7:55
  Speaker 1: But way you were thinking about physics before, So your
• 7:58
  Speaker 1: break from physics is to think about physics.
• 8:00
  Speaker 2: Mostly I was thinking about spreadsheets and email every job spreadsheets, email.
• 8:05
  Speaker 1: And grants and grand proposals, budgets. Oh I see. So
• 8:09
  Speaker 1: then do you actually get to think about physics?
• 8:11
  Speaker 2: Yeah, exactly. Yeah.
• 8:13
  Speaker 1: What if your grand students send you a question about physics,
• 8:15
  Speaker 1: is that the flatter or the former situation? No comment
• 8:22
  Speaker 1: depends on the student. Actually is it an involved spreadsheet
• 8:25
  Speaker 1: or a budget question?
• 8:26
  Speaker 2: Depends Maybe their question is, hey, are you funding me
• 8:29
  Speaker 2: next quarter? Or their question is like, how do we
• 8:31
  Speaker 2: do anomally detection in this space of multiple tracks? You know,
• 8:34
  Speaker 2: depends on and they're asking.
• 8:35
  Speaker 1: I see, and one of those is good and the
• 8:37
  Speaker 1: other one is bad. Is that they're different, they're different different.
• 8:41
  Speaker 1: I see.
• 8:41
  Speaker 4: You are.
• 8:43
  Speaker 1: All right? Well, we have some awesome questions here to
• 8:46
  Speaker 1: the answer. Let's just jump right in. Our first question
• 8:48
  Speaker 1: comes from Nathan from Seattle.
• 8:51
  Speaker 3: Hey, Danieline Horay, my name is Nathan Ramon from Seattle, Washington,
• 8:55
  Speaker 3: and I have a question for y'all. I was watching
• 8:59
  Speaker 3: ant Man last week, and it occurred to me that
• 9:02
  Speaker 3: they are so small in that movie, right, that the
• 9:06
  Speaker 3: speed of light might actually act a little bit differently.
• 9:09
  Speaker 3: They're so small at that point that if the universe
• 9:13
  Speaker 3: is still reacting, like still has the speed of light
• 9:17
  Speaker 3: at the same rate, which it might not necessarily. They
• 9:19
  Speaker 3: do talk a lot about how they're outside of space and.
• 9:21
  Speaker 5: Time, but if it has that same speed limit, if
• 9:25
  Speaker 5: you're so much smaller, it would make it feel to
• 9:30
  Speaker 5: me like White was going way way faster. Sorry from
• 9:33
  Speaker 5: my ramblem, let me know if you need clarification on that,
• 9:36
  Speaker 5: and thanks for all you guys. Do I love your podcast?
• 9:38
  Speaker 1: All right? Awesome question from Nathan, a Marvel fan. It
• 9:41
  Speaker 1: seems well he didn't say whether he liked those movies.
• 9:44
  Speaker 1: He just as he watched them and he had a
• 9:46
  Speaker 1: small opinion about at Man.
• 9:49
  Speaker 2: Well, the cool thing is he was watching it and
• 9:51
  Speaker 2: he was thinking about the physics of it, like, does
• 9:53
  Speaker 2: this make sense? How would this work? What would it
• 9:55
  Speaker 2: actually be like to be that small? Would the experience
• 9:58
  Speaker 2: of it be based on the phil principles of the universe?
• 10:02
  Speaker 1: Have we done an episode on the physics of the
• 10:03
  Speaker 1: Marvel movies? I feel like we talk about them all
• 10:06
  Speaker 1: the time, but have we done like a whole dedicated
• 10:08
  Speaker 1: episode to it.
• 10:09
  Speaker 2: M Is there any physics of the Marvel movies or is.
• 10:11
  Speaker 1: It always it's science fiction?
• 10:14
  Speaker 2: Daniel, It's fiction, for sure.
• 10:17
  Speaker 1: But the an Men movies are pretty good. The first
• 10:19
  Speaker 1: one was really good, the second one was maybe not
• 10:22
  Speaker 1: as good, and the there one was not as good,
• 10:23
  Speaker 1: but overall it's sort of a charming character.
• 10:25
  Speaker 2: Yeah. And I saw the first one. I enjoyed it.
• 10:27
  Speaker 2: And the visit to the quantum Realm I thought was
• 10:29
  Speaker 2: visually very creative. I thought the way they displayed it
• 10:32
  Speaker 2: was very cool, very different from your standard depictions. So
• 10:36
  Speaker 2: it was a lot of fun. I enjoyed it.
• 10:37
  Speaker 1: Did I tell you I know the guy who came
• 10:39
  Speaker 1: up with the term the quantum realm?
• 10:41
  Speaker 2: Oh wow?
• 10:42
  Speaker 1: Yeah, my friend Spiris mcglaucus. He's a physicist and he
• 10:45
  Speaker 1: consulted for Marvel, and one day he was giving them
• 10:47
  Speaker 1: a little spiel in the conference room and he's like,
• 10:49
  Speaker 1: things are very different in the quantum realm, and they're like,
• 10:53
  Speaker 1: we like that, that's in the script.
• 10:54
  Speaker 2: Oh quantum reil.
• 10:55
  Speaker 1: Yeah, he kind of has mixed feelings about what they've
• 10:59
  Speaker 1: done with the ter and the whole idea of quantum physics.
• 11:02
  Speaker 1: But it's pretty cool that he had that contribution.
• 11:05
  Speaker 2: The lesson is be careful what you say around writers.
• 11:08
  Speaker 1: That's right. Yes, we cannot be trusted with the innermost
• 11:12
  Speaker 1: secrets or emotions or physics. But yeah, Nathan has an
• 11:15
  Speaker 1: interesting question. His question is does the speed of light
• 11:18
  Speaker 1: seem faster if you're smaller? So, if you were small,
• 11:23
  Speaker 1: I guess at the level of ant man, does it
• 11:25
  Speaker 1: mean that you see light move faster for you?
• 11:27
  Speaker 2: Yeah? I think this is a really interesting question because
• 11:29
  Speaker 2: it makes us think about the speed of light and
• 11:32
  Speaker 2: the impact on physics, sort of the big and the small,
• 11:36
  Speaker 2: and the way that I think about the speed of light,
• 11:37
  Speaker 2: I think the way most physicists do, is that it's
• 11:40
  Speaker 2: like a ratio between space and time. It's like a
• 11:43
  Speaker 2: conversion between meters and seconds. Like meters is a measurement
• 11:47
  Speaker 2: of distance, seconds is the measurement of time. And the
• 11:50
  Speaker 2: fact that the universe has this number, this maximum speed
• 11:54
  Speaker 2: tells you a relationship between space and time and tells
• 11:58
  Speaker 2: you how to convert a huge distance into a time,
• 12:01
  Speaker 2: and we're often doing that. Like the phrase a light
• 12:03
  Speaker 2: year tells you how far light will go in a year.
• 12:07
  Speaker 2: It sounds kind of like a unit of time, but
• 12:08
  Speaker 2: it's actually distance. You've taken time, you're multiplied by the
• 12:11
  Speaker 2: speed of light, and you've gotten a distance.
• 12:14
  Speaker 1: It's like a measurement that you get by dividing distance
• 12:17
  Speaker 1: divided by time. But does it really tie those two
• 12:20
  Speaker 1: concepts together, like at a fundamental you know, physics level,
• 12:24
  Speaker 1: because like, you know, you can talk about the speed
• 12:25
  Speaker 1: of whorehet down the track that, like my speed is
• 12:29
  Speaker 1: a speed that you can measure and compute, but it
• 12:31
  Speaker 1: doesn't really tell you anything except how out of shape
• 12:35
  Speaker 1: I am.
• 12:36
  Speaker 2: Yeah, Also, the speed of foregete probably changes as a
• 12:39
  Speaker 2: function of time in the universe.
• 12:41
  Speaker 1: And how much chocolate you have, yeah, how many bananas
• 12:44
  Speaker 1: of eaten?
• 12:46
  Speaker 2: But the speed of light really does play a deep
• 12:48
  Speaker 2: role in physics, and it really serves that purpose of
• 12:51
  Speaker 2: converting between space and time. You know, we often talk
• 12:54
  Speaker 2: about like space time being a four dimensional object with
• 12:57
  Speaker 2: the original three dimensions of space and this worth dimension
• 13:00
  Speaker 2: of time. But there's a subtle thing there we don't
• 13:03
  Speaker 2: often talk about, which is that when we include times
• 13:06
  Speaker 2: fourth dimension, we usually multiply it by the speed of light.
• 13:09
  Speaker 2: So the four dimensions are actually like xyz and then ct,
• 13:14
  Speaker 2: not just time because we want to convert it to
• 13:17
  Speaker 2: effectively a distance.
• 13:19
  Speaker 1: Right, Well, you do have to keep the units consistent.
• 13:22
  Speaker 1: But like, for example, if we had a different speed
• 13:23
  Speaker 1: of light in our universe, you know, things would be different.
• 13:27
  Speaker 1: The physics of the universe would be different, but would
• 13:29
  Speaker 1: space itself and would time itself be different.
• 13:32
  Speaker 2: They would be the same, but their relationship would be different.
• 13:35
  Speaker 2: That's what the speed of light is. It's a ratio
• 13:37
  Speaker 2: a relationship between these two different kinds of measurements. Yeah, fundamentally,
• 13:42
  Speaker 2: it really is telling you how these two things relate.
• 13:45
  Speaker 1: H all right, Well, to answer Nathan's questions, let's say
• 13:48
  Speaker 1: I shrink down. Let's say I'm at man or the
• 13:52
  Speaker 1: wasp and I shrink down. Is the speed of lighting?
• 13:56
  Speaker 1: It seemed faster for me? Like if I measure the
• 13:59
  Speaker 1: speed of light, that's scale isn't going to seem faster.
• 14:02
  Speaker 1: Or like if I shine a flashlight will do somehow
• 14:05
  Speaker 1: the flash light seem quicker or brighter or something.
• 14:08
  Speaker 2: Yeah, the speed of light is going to be the
• 14:10
  Speaker 2: same because it's the same ratio between distances and times. Right,
• 14:13
  Speaker 2: So you measure the speed of light. Using a tiny
• 14:15
  Speaker 2: little experiment or a huge experiment, you're going to get
• 14:18
  Speaker 2: the same answer. But if you think of the speed
• 14:20
  Speaker 2: of light as a ratio between distance and time, what
• 14:24
  Speaker 2: it means is that everything seems faster when you're small.
• 14:27
  Speaker 2: Like basically, shorter distances mean shorter times. Things that are
• 14:32
  Speaker 2: smaller can happen faster than things that are bigger.
• 14:36
  Speaker 1: So like, for example, if you not just shrink me,
• 14:38
  Speaker 1: but I use shrink the whole Earth, then for example,
• 14:41
  Speaker 1: light can go around the Earth many more times per second.
• 14:44
  Speaker 2: Yeah, exactly. Or if let's say you build a machine
• 14:46
  Speaker 2: like a computer or even a mechanical device to do something,
• 14:50
  Speaker 2: if it's smaller, it can finish faster than if it's huge.
• 14:54
  Speaker 2: The bigger it is, the longer it'll take to finish,
• 14:56
  Speaker 2: because there's this maximum speed limit. And that's why, like
• 15:00
  Speaker 2: the speed of light seems really really fast to us
• 15:02
  Speaker 2: here on Earth, is this crazy high number. It's basically
• 15:04
  Speaker 2: irrelevant to our experience. It's because things that are almost instantaneous.
• 15:09
  Speaker 2: But imagine if you are a brain made of like stars,
• 15:11
  Speaker 2: you're like a galaxy size brain, it would take like
• 15:14
  Speaker 2: one hundred thousand years to even have a thought.
• 15:16
  Speaker 1: But then your thinking would be slower, so your cognition
• 15:20
  Speaker 1: or your perception of time would be slower. So I
• 15:23
  Speaker 1: think maybe Nathan's question I wonder is whether time will
• 15:27
  Speaker 1: seem to be going faster or maybe it will seem
• 15:30
  Speaker 1: to be the same, right, Because like, if I'm the
• 15:32
  Speaker 1: size of a galaxy, my thoughts are going to be
• 15:35
  Speaker 1: super slow. And so even though any effect I'm in
• 15:38
  Speaker 1: the sea is going to be super slow because with
• 15:40
  Speaker 1: the distances, my thoughts are going to be slow. And
• 15:42
  Speaker 1: so therefore the experience of being that person is going
• 15:47
  Speaker 1: to be the same as our experience here on Earth.
• 15:49
  Speaker 2: Yeah. I think there's a few things there to disentangle,
• 15:51
  Speaker 2: but basically you're right. Number one, if you measure the
• 15:54
  Speaker 2: speed of light, you're going to get the same number.
• 15:55
  Speaker 2: It doesn't matter if you're a galaxy brain or an
• 15:57
  Speaker 2: ant brain, right, as long as you do it correctly,
• 15:59
  Speaker 2: you're going to get this same number. Number two, things
• 16:02
  Speaker 2: do seem to happen faster when you're smaller because you're
• 16:05
  Speaker 2: just not as limited by this speed of light. Things
• 16:07
  Speaker 2: have shorter distances to cross in order to accomplish some
• 16:10
  Speaker 2: thinking or some task or whatever. Number three, Finally, we
• 16:14
  Speaker 2: don't really know what it would be like to experience
• 16:17
  Speaker 2: that what it seemed like time goes faster. We don't
• 16:20
  Speaker 2: understand our experience of time or why we seem to
• 16:23
  Speaker 2: experience it at you know, one second per second. So
• 16:25
  Speaker 2: I don't know what it would be like to be
• 16:27
  Speaker 2: a galaxy brain. They might have the same kind of
• 16:29
  Speaker 2: subjective experience we do.
• 16:31
  Speaker 1: Yeah, Or like thinking about the shrinking case, like if
• 16:34
  Speaker 1: I shrink down to enman size, now my brain is smaller,
• 16:37
  Speaker 1: Like the distances between my neurons are smaller, and so
• 16:41
  Speaker 1: maybe my thinking will be sort of like hypercharge. Yeah,
• 16:44
  Speaker 1: like I'll have a million of thoughts in the same
• 16:46
  Speaker 1: amount of time that it used to take me to
• 16:48
  Speaker 1: have one thought, and so I'll be sort of super
• 16:51
  Speaker 1: bored looking at the bigger world, but looking at the
• 16:55
  Speaker 1: small world, maybe it'll just seem like the same regular
• 16:58
  Speaker 1: because things are moving faster. But I'm also like having
• 17:00
  Speaker 1: a bazillion more cycles in my brain than I did before.
• 17:04
  Speaker 2: Yeah, exactly, So we don't know what the experience would
• 17:07
  Speaker 2: be like. This is an interesting wrinkle of evolutionary biology.
• 17:09
  Speaker 2: There also which is wondering, like could humans be smarter?
• 17:13
  Speaker 2: You can imagine being smarter by having like a bigger
• 17:16
  Speaker 2: brain more neurons, but then it's harder to get that
• 17:18
  Speaker 2: brain through the birth canal. You could also imagine getting
• 17:22
  Speaker 2: smarter by having more neurons by making the neurons smaller.
• 17:25
  Speaker 2: But I was reading a paper that said that if
• 17:27
  Speaker 2: neurons got any smaller, they would be noisier, like more
• 17:31
  Speaker 2: randomness and fuzz so it might not actually add computing power,
• 17:35
  Speaker 2: So we might be at like the sweet spot of
• 17:37
  Speaker 2: like the densest neuronal systems.
• 17:40
  Speaker 1: Well, the other thing to consider is that neurons work
• 17:42
  Speaker 1: by bioelectricity, right, biochemistry, not necessarily by like transmitting electrons. Right.
• 17:50
  Speaker 1: It all depends on sort of reactions and electric fields
• 17:55
  Speaker 1: and like molecules moving in and out of the little
• 17:57
  Speaker 1: cell walls.
• 17:58
  Speaker 2: Yeah, exactly, if you could actually shrink all that stuff,
• 18:02
  Speaker 2: it would happen faster. Of course, you know, the physics
• 18:04
  Speaker 2: wouldn't work if you shrink all that stuff because all
• 18:06
  Speaker 2: the numbers would change. So the fundamental physics of ant
• 18:09
  Speaker 2: Man is silly because you know, if he's shrunk down
• 18:12
  Speaker 2: the size of an electron, then how big are his electrons? Right?
• 18:15
  Speaker 1: Right, So basically we get into the fuzzy area of
• 18:18
  Speaker 1: like perception and the subjective experience. But generally speaking, I
• 18:22
  Speaker 1: think from a physics point of view, if you were
• 18:24
  Speaker 1: down to the size of ant man, the light would
• 18:27
  Speaker 1: sort of seem to travel faster, right, Like it would
• 18:29
  Speaker 1: go one body length in a much shorter amount of
• 18:32
  Speaker 1: time than it would go at our size.
• 18:35
  Speaker 2: Yeah, your body would be shorter, so light would go
• 18:37
  Speaker 2: across you faster, and I think a lot of things
• 18:40
  Speaker 2: would happen faster. I don't know how he can say
• 18:42
  Speaker 2: what it would be like though, to experience it.
• 18:45
  Speaker 1: I wonder if it would be even that different, Like
• 18:47
  Speaker 1: what's the difference between almost intustanious and almost almost instaneous.
• 18:51
  Speaker 1: Maybe the difference is not that great, or maybe he's
• 18:54
  Speaker 1: thinking about it, like when admin goes down to like
• 18:57
  Speaker 1: the quantum size.
• 18:58
  Speaker 2: Yeah, but as you say, distances are already so small
• 19:01
  Speaker 2: compared to the speed of light, then our experience is
• 19:03
  Speaker 2: very difficult to even tell that it's not instantaneous. It
• 19:06
  Speaker 2: took people a long time to be able to devise
• 19:08
  Speaker 2: experiments to measure the speed of light. That to be
• 19:11
  Speaker 2: very very clever, because it's so blazingly fast compared to
• 19:14
  Speaker 2: the distances in which we live. If you realize galaxy
• 19:17
  Speaker 2: brain and then you got shrunk down to ant man,
• 19:19
  Speaker 2: that might be more dramatic.
• 19:20
  Speaker 1: Yeah, Or I wondered maybe the equivalent conversion is like,
• 19:23
  Speaker 1: let's say you and I are living in our everyday
• 19:25
  Speaker 1: lives here, but suddenly the speed of light goes up
• 19:28
  Speaker 1: by a factor of ten. Let's say it was now
• 19:30
  Speaker 1: three million kilometers per second. Would we even notice a difference.
• 19:33
  Speaker 2: We wouldn't notice the difference here on Earth, but suddenly
• 19:36
  Speaker 2: the rest of the universe would effectively be closer to us.
• 19:39
  Speaker 2: You know, we could see things happening faster, We could
• 19:41
  Speaker 2: get places faster. The size of a galaxy would effectively
• 19:45
  Speaker 2: seem smaller.
• 19:47
  Speaker 1: Well, seem smaller, No, it'll still be the same distance.
• 19:50
  Speaker 1: We would just see it sooner.
• 19:52
  Speaker 2: Yeah, like our information bubble would be larger. The distance
• 19:55
  Speaker 2: over which things appear to happen instantaneously would be bigger.
• 20:00
  Speaker 1: Maybe see further out or or I guess what we
• 20:02
  Speaker 1: see would be more up to date, Yeah.
• 20:05
  Speaker 2: More recent exactly. The time lag would no longer be
• 20:08
  Speaker 2: noticeable for things that are close to us. Is to
• 20:10
  Speaker 2: look even further out to notice that time lag?
• 20:12
  Speaker 1: Well, I feel like they're not even noticeable. Now, like
• 20:16
  Speaker 1: I can tell the difference between a billion year old
• 20:18
  Speaker 1: star and a million year.
• 20:20
  Speaker 2: Old star, astronomers can All.
• 20:25
  Speaker 1: Right, well, I think that answer is a question, which
• 20:26
  Speaker 1: is that the speed of light would not be different,
• 20:30
  Speaker 1: but maybe your experience of it would be different. All right, Well,
• 20:33
  Speaker 1: thanks for that question, Nathan. Let's get to our other questions.
• 20:36
  Speaker 1: We have one here about quantum entanglement and time travel,
• 20:40
  Speaker 1: so we'll get to those, but first let's take a
• 20:42
  Speaker 1: quick break. All right, we're answering listener questions here today,
• 20:57
  Speaker 1: and our next question is about quantum entanglement.
• 21:01
  Speaker 4: How to Daniel question for you? Assume we know particle
• 21:06
  Speaker 4: A and the particle B are entangled, and for simplicity's sake,
• 21:11
  Speaker 4: let's say the states are positive or negative, and there's
• 21:15
  Speaker 4: a fifty to fifty chance. Now, what would happen if
• 21:20
  Speaker 4: two independent observers we can call them A and B
• 21:25
  Speaker 4: for their respective particles, observed these two particles at the
• 21:32
  Speaker 4: exact same time. This question really breaks my brain. The
• 21:37
  Speaker 4: more I think about it, the less I feel like
• 21:40
  Speaker 4: I understand special relativity, and the less I feel like
• 21:43
  Speaker 4: I understand quantum mechanics. And adding to their question, is
• 21:49
  Speaker 4: it even possible to make two observations with two observers
• 21:55
  Speaker 4: at the same time. I really appreciate it. Thanks for
• 21:58
  Speaker 4: helping me understand.
• 22:00
  Speaker 1: All right, Well, that's quite a mindful of a question here.
• 22:03
  Speaker 1: And Daniel, I notice he asked a question of you,
• 22:06
  Speaker 1: not me, So I think I can just sit this
• 22:08
  Speaker 1: one out because honestly, I don't understand the question. I'm
• 22:13
  Speaker 1: a bit entangled in the whole flurry of words.
• 22:16
  Speaker 2: You felt like some of the other physics questions were
• 22:17
  Speaker 2: aimed towards you.
• 22:18
  Speaker 1: The last one did say Daniel and Jorge, I think
• 22:21
  Speaker 1: I was one of the targets. And sometimes they say hey,
• 22:24
  Speaker 1: guys plural, so it does mean the two of us.
• 22:28
  Speaker 2: Well, I think he's also counting on you to help
• 22:30
  Speaker 2: me translate my understanding into something.
• 22:32
  Speaker 1: Ever, no, no, no, I feel snubbed, So I'm not
• 22:36
  Speaker 1: even gonna chime in.
• 22:37
  Speaker 2: I'm gonna do my best, but I'm pretty sure you're
• 22:39
  Speaker 2: going to have a hard time not interrupting.
• 22:44
  Speaker 1: What are you trying to say?
• 22:45
  Speaker 2: What are you trying to say? It's your job and
• 22:47
  Speaker 2: you do it beautifully, man.
• 22:48
  Speaker 1: What are you trying to say? Daniel? Did I interrupt you?
• 22:50
  Speaker 2: Yes, exactly.
• 22:54
  Speaker 1: All right, So what is the question? I know it's
• 22:56
  Speaker 1: about quantum entanglement, but it didn't quite get the gist
• 22:59
  Speaker 1: of it.
• 23:00
  Speaker 2: Yeah, so the question is about quantum entanglement and special
• 23:03
  Speaker 2: relativity and how these two things come together. But let's
• 23:06
  Speaker 2: start just with the basic issue of quantum entanglement, which
• 23:09
  Speaker 2: is weird enough, right. Quantum entanglement says what happens if
• 23:13
  Speaker 2: you have two particles that are like the output of
• 23:16
  Speaker 2: a single process. Something makes two particles, and so their
• 23:19
  Speaker 2: fate is connected. Like let's say you have two electrons created,
• 23:22
  Speaker 2: and one has to be spin up and one has
• 23:24
  Speaker 2: to be spinned down because of the way they're made.
• 23:26
  Speaker 2: The universe doesn't care which one is spin up and
• 23:28
  Speaker 2: which one is spin down as long as they point opposite. Now,
• 23:32
  Speaker 2: if you take those two particles and you send them
• 23:34
  Speaker 2: different directions, they're now far apart. Quantum entanglement says that
• 23:37
  Speaker 2: they're still somehow connected, that their fates are joined, And
• 23:41
  Speaker 2: so if you measure one to be spin up, you
• 23:43
  Speaker 2: now know the other one is spin down. But it's
• 23:45
  Speaker 2: more than just like knowing that they have to be opposite.
• 23:49
  Speaker 2: Quantum entanglement tells us that they're actually not determined that
• 23:52
  Speaker 2: neither one is spin up or spin down. They both
• 23:55
  Speaker 2: have that possibility, and that as soon as you measure one,
• 23:58
  Speaker 2: then the fate of the other one is determined. That's
• 24:01
  Speaker 2: a weird bit about quantum entanglement.
• 24:03
  Speaker 1: Oh wait, you want me to jump in now you're
• 24:06
  Speaker 1: going to interrupt. Yeah, So that's the basic of entanglement, right,
• 24:11
  Speaker 1: Like you have two quantum things, like a particle or
• 24:14
  Speaker 1: an atom or some sort of quantum object, and it's fuzzy,
• 24:17
  Speaker 1: you don't know what it actually is inside. But if
• 24:20
  Speaker 1: two of them have some sort of shared history, some
• 24:22
  Speaker 1: sort of shared origin that ties them together, that's what
• 24:25
  Speaker 1: quantum intalgent and guildment is.
• 24:27
  Speaker 2: That's right, there's some correlation between them that's created locally
• 24:30
  Speaker 2: when they're like both made and sent apart, but then
• 24:33
  Speaker 2: the correlation persists as they get further and further apart.
• 24:36
  Speaker 2: And again, this is not a scenario where one of
• 24:38
  Speaker 2: them actually is spin up and the other one actually
• 24:41
  Speaker 2: is spin down and we just don't know. We've proven
• 24:44
  Speaker 2: through a whole complicated series of experiments suggested by John Bell,
• 24:48
  Speaker 2: that they actually are undetermined until you measure. So the
• 24:51
  Speaker 2: weird bit and the thing that makes it hard to
• 24:53
  Speaker 2: reconcile with special relativity is that, apparently this happens instantaneously.
• 24:57
  Speaker 2: You have these two particles that have a shared face,
• 25:00
  Speaker 2: but they're both undetermined. Now you send them like five
• 25:03
  Speaker 2: kilometers apart, you measure one of them, you get to
• 25:05
  Speaker 2: spin up instantly. The other one has to be spinned down.
• 25:09
  Speaker 2: It went from I don't know, maybe up or down
• 25:11
  Speaker 2: to has to be down instantaneously across space and.
• 25:15
  Speaker 1: Time, right, which that first glance seems to violate the
• 25:18
  Speaker 1: speed of light. Right, because something changed in one part
• 25:21
  Speaker 1: of the universe, and then it suddenly costs something else
• 25:24
  Speaker 1: to change in another part, seemingly instantaneously.
• 25:28
  Speaker 2: Exactly what you said is important. You said it violates
• 25:30
  Speaker 2: the speed of light, and that's correct. This is something
• 25:32
  Speaker 2: that happens faster than the speed of light. Speed of
• 25:35
  Speaker 2: light says is a limit to how fast things can
• 25:38
  Speaker 2: happen across the universe. This is instantaneous, but doesn't actually
• 25:43
  Speaker 2: break special relativity because you're not sending information faster than
• 25:47
  Speaker 2: the speed of light. Like the quantum state is non local,
• 25:50
  Speaker 2: It stretches over space and collapses instantaneously. The whole thing
• 25:55
  Speaker 2: at the same time, but you can't actually use that
• 25:57
  Speaker 2: to send information. Are often writing in and saying, well,
• 26:01
  Speaker 2: can't I send information by making a measurement and the
• 26:04
  Speaker 2: other person's going to see that theirs is now collapsed.
• 26:07
  Speaker 2: You can't actually tell when your probabilities have collapsed. All
• 26:10
  Speaker 2: you can do is measure or not measure. When you
• 26:13
  Speaker 2: measure your particle, you don't know if it was already
• 26:15
  Speaker 2: collapsed or if you're collapsing it by measuring it.
• 26:18
  Speaker 1: Right. Also, when you collapse one of them, it's not
• 26:20
  Speaker 1: like you're sending that information to the other person. Like
• 26:24
  Speaker 1: let's say we entangle to particles. I have one, and
• 26:26
  Speaker 1: when we split up a part I have one, you
• 26:28
  Speaker 1: have one. If I open mind, I measure it and
• 26:31
  Speaker 1: I see it that for example, it's up, and I
• 26:34
  Speaker 1: know that yours is down. Like I know something about
• 26:37
  Speaker 1: your particle, But that doesn't mean you know that about
• 26:39
  Speaker 1: your particle. Like to you over there in Irvine, your
• 26:43
  Speaker 1: particle is still this quantum object that could be fifty
• 26:45
  Speaker 1: percent up or down. So like, no information is actually
• 26:48
  Speaker 1: traveled unless I send you an email, which would then
• 26:51
  Speaker 1: be limited by the speed of light exactly, and or
• 26:54
  Speaker 1: my sale signal exactly. And if I still have my
• 26:57
  Speaker 1: particle in the box, you measure yours. I can't tell,
• 27:00
  Speaker 1: well if you've measured yours, like mine doesn't look any
• 27:02
  Speaker 1: different if I'm not measuring it, I'm just waiting to
• 27:05
  Speaker 1: measure it. I don't know if you've measured yours or not.
• 27:07
  Speaker 1: I can't tell that you have measured it. So it's
• 27:09
  Speaker 1: like information about something far away has been revealed to
• 27:13
  Speaker 1: me instantaneously, But that doesn't mean that information actually got
• 27:17
  Speaker 1: transmitted from one place to the other.
• 27:19
  Speaker 2: Yeah, exactly.
• 27:21
  Speaker 1: So then what's the actual question here?
• 27:22
  Speaker 2: So the question is what happens we measure them at
• 27:24
  Speaker 2: the same time. Who collapses the wave function? Mmmm?
• 27:29
  Speaker 1: So we each have a particle that's been entangled the
• 27:32
  Speaker 1: other and we open it at the same time, nothing happens.
• 27:35
  Speaker 2: Right, Well, this is a really interesting question.
• 27:38
  Speaker 1: Like you'll find that you'll find yours up and I'll
• 27:40
  Speaker 1: find my down, or I'll find mine up and you'll
• 27:42
  Speaker 1: find yours. Now that's all that really happens, is it.
• 27:46
  Speaker 2: Yeah? I love your answer, and you're right from the
• 27:48
  Speaker 2: point of view of like what we experience. You open
• 27:50
  Speaker 2: your box, you measure it up or you measure it down.
• 27:52
  Speaker 2: But I think what he's asking is, like, what's happening
• 27:55
  Speaker 2: behind the scenes? You know, what is the wave function doing?
• 27:58
  Speaker 2: Even if we can't observe it and can't measure it
• 28:00
  Speaker 2: and can't ever know what in theory is the explanation
• 28:03
  Speaker 2: for how this happens. And I think there's touching on
• 28:05
  Speaker 2: a deeper question, which is about simultaneity. We talked on
• 28:09
  Speaker 2: the podcast how special relativity tells us that at the
• 28:12
  Speaker 2: same time is a fuzzy concept. Two events could occur
• 28:16
  Speaker 2: at the same time for one person, but not for
• 28:17
  Speaker 2: somebody else if they have a different velocity or different
• 28:20
  Speaker 2: location in space. And so this seems very fuzzy all
• 28:23
  Speaker 2: of a sudden, like two people measure the wave function
• 28:25
  Speaker 2: at the same time, what happens to that wave function?
• 28:29
  Speaker 2: And what happens according to somebody flying by in a
• 28:31
  Speaker 2: spaceship at nearly the speed of light?
• 28:32
  Speaker 1: So then what's the answer for our question? Asker?
• 28:35
  Speaker 2: So the best answer to the way you just gave,
• 28:37
  Speaker 2: which is this is not a physical problem.
• 28:39
  Speaker 1: This is only I answered the question even though he
• 28:42
  Speaker 1: didn't ask me, I'm the one who ended up answering.
• 28:44
  Speaker 2: You answered it. In the classical dismissive way, which is like,
• 28:47
  Speaker 2: it doesn't matter. It's just a philosophy question about what's
• 28:49
  Speaker 2: happening to the wave function. It's not a question.
• 28:54
  Speaker 1: I mean, I was being pejorative maybe.
• 28:58
  Speaker 2: But it's true though it's an important distinction. We know
• 29:00
  Speaker 2: what would happen. I measure mine, you measure yours done,
• 29:03
  Speaker 2: it doesn't really matter, right, But the question is what's
• 29:06
  Speaker 2: happening behind the scenes, which is a philosophical question about
• 29:09
  Speaker 2: something we may never be able to know, like what
• 29:12
  Speaker 2: is the wave function really? And there's whole philosophical debates
• 29:14
  Speaker 2: about whether the wave function is just a mathematical tool
• 29:17
  Speaker 2: we use to make these calculations, or if it's a
• 29:19
  Speaker 2: real physical thing in the universe. And so there's long
• 29:23
  Speaker 2: answer is it depends on what you think the wave
• 29:25
  Speaker 2: function is. It depends on your philosophical interpretation of quantum mechanics.
• 29:30
  Speaker 2: And we can walk through a few of those examples.
• 29:32
  Speaker 1: Like is there a wave function that physically connects my
• 29:36
  Speaker 1: particle to your particle or is the wave function just
• 29:39
  Speaker 1: some mathematical tool we used to explain things when things
• 29:42
  Speaker 1: are not far apart. Yeah, and then when you split them,
• 29:45
  Speaker 1: maybe actually you get two wave functions or maybe there's
• 29:48
  Speaker 1: no such thing as a physical common wave.
• 29:50
  Speaker 2: Function, or maybe there are many wave functions, or maybe
• 29:53
  Speaker 2: the wave function never collapses. Now in the standard interpretation
• 29:56
  Speaker 2: of quantum mechanics, which I'll say up front is nonsense,
• 29:59
  Speaker 2: the Copenhague interpretation, which doesn't work and is deeply flawed,
• 30:03
  Speaker 2: but it's still the one most people think about and
• 30:05
  Speaker 2: is most often taught. In that interpretation, the wave function
• 30:08
  Speaker 2: is a thing, and it's real, and before you measure something,
• 30:11
  Speaker 2: it allows for multiple possibilities, like the wave function says
• 30:14
  Speaker 2: you might be up and you might be down. And
• 30:16
  Speaker 2: then when you make a measurement with a classical object
• 30:19
  Speaker 2: where classical object is not defined, just something big, then
• 30:23
  Speaker 2: it collapses and it chooses one of these options. And
• 30:26
  Speaker 2: I think it's in that scenario that the question is asking,
• 30:28
  Speaker 2: like number one, what happens if two people make the
• 30:30
  Speaker 2: measurement at the same time, who collapses it? And then
• 30:33
  Speaker 2: what happens to an observer flying by the speed of light?
• 30:36
  Speaker 2: The answer is sort of nonsense. Like number one, if
• 30:39
  Speaker 2: two people make your measurement at the same time, well,
• 30:41
  Speaker 2: you can't do that in Copenhagen interpretation because you can
• 30:45
  Speaker 2: only make one measurement on a wave function at a time.
• 30:48
  Speaker 2: It's just not allowed because making a measurement changes the
• 30:51
  Speaker 2: wave function, and you have to do them in sequence.
• 30:54
  Speaker 2: That's why it's like important whether you're measuring position or
• 30:57
  Speaker 2: momentum first, or momentum and then position, because every measurement
• 31:01
  Speaker 2: change is a wave function. There's no way to even
• 31:03
  Speaker 2: describe making two measurements at the same time.
• 31:06
  Speaker 1: I see, well, if there is sort of like a
• 31:08
  Speaker 1: physical wave function connecting my particle to your particle, then
• 31:12
  Speaker 1: you do sort of get the sense of that there
• 31:14
  Speaker 1: is a shared now.
• 31:16
  Speaker 2: But even though it's quantum mechanical, unless you're gonna pixelate time,
• 31:19
  Speaker 2: time itself is infinitely divisible, So saying you're making two
• 31:23
  Speaker 2: measurements at the same time would mean you're like exactly
• 31:26
  Speaker 2: matching those two moments.
• 31:29
  Speaker 1: Meaning like maybe there's no way to know who collapsed
• 31:31
  Speaker 1: it first unless we somehow sink clocks or something beforehand
• 31:37
  Speaker 1: and then we compare clocks afterwards.
• 31:39
  Speaker 2: But you'd have to sink them exactly perfectly to like
• 31:41
  Speaker 2: an infinite number of digits, which seems impossible, right, And
• 31:45
  Speaker 2: it gets even weirder if you ask, like what happens
• 31:47
  Speaker 2: according to other observers, Like, what if I make my
• 31:50
  Speaker 2: measurement and then ten seconds later you make your measurement,
• 31:53
  Speaker 2: and now, in our frame of reference, I was first
• 31:55
  Speaker 2: and you were second. But somebody flying by at the
• 31:58
  Speaker 2: speed of light, they could your measurement happen first before
• 32:02
  Speaker 2: mine because the order events is not guaranteed in special
• 32:05
  Speaker 2: relativity depends on the observer.
• 32:07
  Speaker 1: Interesting, So I think what you're saying is that in
• 32:09
  Speaker 1: the quantum realm, at man would not know what time
• 32:14
  Speaker 1: it is.
• 32:16
  Speaker 2: I'm saying that this picture of the wave function collapsing
• 32:18
  Speaker 2: and happening instantly across space in time, that picture itself
• 32:22
  Speaker 2: doesn't really work in the Coponhagd interpretation. Imagine a more
• 32:26
  Speaker 2: complex situation, for example, like an observer flying by and
• 32:29
  Speaker 2: then changing directions and going the other way. As they
• 32:32
  Speaker 2: change directions, their concept of what happens first when happens
• 32:35
  Speaker 2: second changes, So you could arrange a trajectory where they're
• 32:39
  Speaker 2: seeing me make my measurement first, and then later they
• 32:42
  Speaker 2: see you make your measurement first because their velocity is changing.
• 32:46
  Speaker 2: And in that scenario, the wave function collapses in one
• 32:49
  Speaker 2: way and then uncollapses and recollapses in a different way,
• 32:53
  Speaker 2: so like the whole picture becomes very confusing and it's
• 32:55
  Speaker 2: kind of nonsensical, but it doesn't change anything physical. This
• 32:58
  Speaker 2: is just philosophical and there are other philosophical approaches to
• 33:02
  Speaker 2: quantum mechanics that don't have these issues that the Copenhagen
• 33:05
  Speaker 2: interpretation has, and Copenhagen is already known to be nonsense
• 33:09
  Speaker 2: because this division between like what is quantum and what
• 33:11
  Speaker 2: is classical is not even defined or described.
• 33:14
  Speaker 1: Well, it seems like kind of the main problem is
• 33:16
  Speaker 1: that you're basically trying to put together general relativity and
• 33:20
  Speaker 1: quantum mechanics, which, as we've talked about a million times
• 33:23
  Speaker 1: in this podcast, like they don't really play well with
• 33:25
  Speaker 1: each other, right, Like, quantum mechanics is kind of a
• 33:27
  Speaker 1: local effect and general relativity things that happen over maybe
• 33:31
  Speaker 1: big distances or big amounts of time, and it involves
• 33:35
  Speaker 1: curature time and space, and so we don't really know
• 33:39
  Speaker 1: how to marry those two.
• 33:40
  Speaker 2: Well, I'm not sure we're getting into general relativity here.
• 33:43
  Speaker 2: Really all these questions are about special relativity, and we
• 33:45
  Speaker 2: do know how to marry special relativity and quantum mechanics
• 33:49
  Speaker 2: into a theory. We have relativistic quantum mechanics, and we
• 33:51
  Speaker 2: have quantum field theories, and those make predictions about all
• 33:55
  Speaker 2: the measurements, and those all work. The philosophical underpinnings of
• 33:58
  Speaker 2: what happens when you try to bring these two together
• 34:01
  Speaker 2: is more complicated, and there people have a lot of disagreements.
• 34:04
  Speaker 2: But what's going on behind the scenes.
• 34:06
  Speaker 1: Well, I think maybe the basic conclusion is that I
• 34:08
  Speaker 1: answered this question and even though I wasn't asked for you.
• 34:17
  Speaker 1: All right, Well, let's get to our last question, which
• 34:19
  Speaker 1: is about time travel, and the question people should think
• 34:22
  Speaker 1: about during this break is do we already answer this
• 34:24
  Speaker 1: question or are we going to answer it in the future.
• 34:28
  Speaker 2: Or have we already answered it in the future?
• 34:30
  Speaker 1: Yeah, or have we already asked this question about answering
• 34:33
  Speaker 1: the question in the past?
• 34:35
  Speaker 2: Have we already made every possible time travel check?
• 34:40
  Speaker 1: Let's go back in time and make some more but
• 34:42
  Speaker 1: first let's take a quick break. Or are we're answering
• 34:57
  Speaker 1: listening to questions here today? And our last question of
• 34:59
  Speaker 1: the day is about the past, the present, the future
• 35:04
  Speaker 1: and whether we can move between them.
• 35:07
  Speaker 6: Hey, guys, this is Trevor. I was recently listening to
• 35:10
  Speaker 6: an episode of the podcast in which Daniel mentions that
• 35:13
  Speaker 6: we have never observed anything that was moving backwards in time.
• 35:17
  Speaker 6: My question is, how would we be able to identify
• 35:20
  Speaker 6: whether an object we're observing was moving backwards in time?
• 35:24
  Speaker 6: What characteristics would make backwards motion in time distinguishable to us?
• 35:29
  Speaker 6: Are we sure we would even be able to observe
• 35:31
  Speaker 6: a reverse time object while we are moving forward in time.
• 35:35
  Speaker 6: I love what you guys do, and I sincerely appreciate
• 35:37
  Speaker 6: you taking my.
• 35:38
  Speaker 1: Question interesting question. I feel like this question relates to
• 35:42
  Speaker 1: the movie Tenet. Have you seen that movie?
• 35:45
  Speaker 2: I've seen that movie and I saw that. Christopher Nolan
• 35:47
  Speaker 2: was like, people who try to understand Tenant are not
• 35:50
  Speaker 2: really getting what I was after. Like, the movie just
• 35:52
  Speaker 2: doesn't make sense.
• 35:55
  Speaker 1: He's like, why are people throwing my movie at the wall?
• 35:58
  Speaker 1: It's signs fiction people, It's.
• 36:00
  Speaker 2: Not supposed to make sense, he says, as he presents
• 36:03
  Speaker 2: and asks you to solve it.
• 36:04
  Speaker 1: Like what, Yeah, It's all about the experience of the mystery, right.
• 36:08
  Speaker 2: I'm not being a physicist. I'm just like experiencing the universe. Man,
• 36:11
  Speaker 2: I'm not trying to fit it all together in my
• 36:13
  Speaker 2: head in the way that makes sense. Yeah.
• 36:15
  Speaker 1: Yeah, maybe your wall would be intact if he took
• 36:18
  Speaker 1: that attitude more. But yeah, in the movie Tenet, they
• 36:20
  Speaker 1: sort of figure out how to make something move backwards
• 36:24
  Speaker 1: in time, Like they can make a bullet move backwards
• 36:28
  Speaker 1: in time, and so even though we're moving forwards in time,
• 36:30
  Speaker 1: the bullet is moving backwards in time. And at some
• 36:33
  Speaker 1: point they make people move backwards in time.
• 36:35
  Speaker 2: Right, I don't know. I went back in time and
• 36:37
  Speaker 2: erased that movie from them, Right.
• 36:41
  Speaker 1: I think that's the basic question that Trevor has here,
• 36:45
  Speaker 1: which is like, could something move backwards in time? And
• 36:49
  Speaker 1: would we know it's moving backwards in time?
• 36:51
  Speaker 2: Yeah, it's a really cool question with a lot of
• 36:53
  Speaker 2: interesting subtlety, depending exactly what you mean by move backwards
• 36:57
  Speaker 2: in time, because there's a fundamental question we have about time,
• 37:01
  Speaker 2: which is like why does it flow forward? If you
• 37:04
  Speaker 2: look at the equations of physics, they seem to work
• 37:08
  Speaker 2: just as well forwards and backwards. You know, for most things.
• 37:12
  Speaker 2: If you took a video of them, and then you
• 37:14
  Speaker 2: play the video forwards and you play the video backwards,
• 37:17
  Speaker 2: the laws of physics would work just as well for
• 37:20
  Speaker 2: both scenarios Like you're playing pool and you hit a
• 37:23
  Speaker 2: ball and they bounce off each other. You could play
• 37:26
  Speaker 2: that whole reaction backwards and the same thing would work
• 37:29
  Speaker 2: according to the laws of momentum and all that kind
• 37:31
  Speaker 2: of stuff.
• 37:32
  Speaker 1: In like a perfect world, in a perfect bouncy ball
• 37:35
  Speaker 1: that doesn't lose energy each time it bounces, like a
• 37:38
  Speaker 1: bouncing ball moving forwards in time looked exactly like a
• 37:41
  Speaker 1: bouncing ball moving backwards sometimes.
• 37:43
  Speaker 2: Yeah, and we could start with the individual particles, so
• 37:45
  Speaker 2: we're not thinking about like ten to the twenty nine
• 37:47
  Speaker 2: objects and thermodynamics yet for like the individual particles, these
• 37:52
  Speaker 2: rules work just as well forwards and backwards in time.
• 37:55
  Speaker 1: Meaning like if you records and particles having some interactions
• 38:00
  Speaker 1: when you play it backwards, that's also a perfectly feasible
• 38:03
  Speaker 1: thing for the particles to do, or what you observe
• 38:06
  Speaker 1: on doing is also perfectly feasible.
• 38:09
  Speaker 2: Yes, ninety nine point ninety nine percent. There's a little
• 38:11
  Speaker 2: asterisk there about how some particle interactions do prefer one
• 38:16
  Speaker 2: direction in time, but it's a really really tiny effect.
• 38:20
  Speaker 1: So then what are you saying. Are you're saying like
• 38:22
  Speaker 1: we are technically all moving backwards and forwards in time,
• 38:26
  Speaker 1: or there's no meaning to something moving backwards in time.
• 38:30
  Speaker 2: I think that implies something really interesting about the universe,
• 38:33
  Speaker 2: about causality. It implies that, of course the past determines
• 38:37
  Speaker 2: the future, right, things flow, the laws of physics determine things,
• 38:41
  Speaker 2: but also that the future is unique because the future
• 38:45
  Speaker 2: is determined by the past. But you could also flip
• 38:48
  Speaker 2: it the other way around. You could say the future
• 38:50
  Speaker 2: determines the past, right, Like if there's only one possible
• 38:53
  Speaker 2: future for every past, and you can go from the
• 38:56
  Speaker 2: future and predict the past if they're you know, connected
• 38:59
  Speaker 2: by the laws of physics in the same way, then
• 39:01
  Speaker 2: like what direction is causality anyway? And so that's what
• 39:05
  Speaker 2: we mean when we say, like which direction does time flow?
• 39:09
  Speaker 2: The laws of physics don't care. There's sort of like
• 39:11
  Speaker 2: time independent.
• 39:13
  Speaker 1: Right, Well, you sort of get into the idea of
• 39:14
  Speaker 1: determinism and whether things move in a predictable way, but
• 39:18
  Speaker 1: doesn't quantum mechanics sort of do away with that, Like,
• 39:21
  Speaker 1: you know, I can't really predict the future because what
• 39:24
  Speaker 1: absurdin particle is going to do is sort of random
• 39:26
  Speaker 1: according to quantum physics. And if I have an outcome
• 39:29
  Speaker 1: of a particle, I can't really trace back its history
• 39:33
  Speaker 1: because there was a random process somewhere in the middle.
• 39:36
  Speaker 2: Yeah, great question, and there's a couple directions there. Now,
• 39:40
  Speaker 2: if you only have quantum interactions, then what you said
• 39:43
  Speaker 2: is not technically correct because quantum information is preserved and
• 39:46
  Speaker 2: you can go forwards and backwards, like if there's no
• 39:49
  Speaker 2: wave function collapse, then the future is completely predicted by
• 39:53
  Speaker 2: the past, and you can derive the past from the future.
• 39:56
  Speaker 2: You know. Quantum information just flows through time like particles
• 39:59
  Speaker 2: into react with each other. There may be randomness, but
• 40:02
  Speaker 2: if there's no wave function collapse, so you don't force
• 40:04
  Speaker 2: the universe to choose from those probability distributions, then all
• 40:08
  Speaker 2: that information is preserved. So wave function collapse does break
• 40:12
  Speaker 2: that deep rule of quantum mechanics, which is another reason
• 40:15
  Speaker 2: why wave function collapse is kind of nonsense from a
• 40:18
  Speaker 2: philosophical and a physics point of view and not something
• 40:21
  Speaker 2: we understand.
• 40:22
  Speaker 1: Wait, wait, we're having your crossover here with another question.
• 40:25
  Speaker 1: The other question.
• 40:26
  Speaker 2: Connected man in the quantum realm, there is a larger
• 40:30
  Speaker 2: sense in which we think quantum mechanics does yield a
• 40:33
  Speaker 2: definition of time because the randomness of quantum mechanics does
• 40:37
  Speaker 2: affect like multiple particles, And we talked about an individual
• 40:40
  Speaker 2: particle and what happens to it. Now, imagine like ten
• 40:43
  Speaker 2: to the thirty particles. Instead of tracing each of them individually,
• 40:46
  Speaker 2: you're thinking about the population of those particles. What are
• 40:49
  Speaker 2: they more likely to do or less likely to do?
• 40:52
  Speaker 2: And because they're governed by randomness.
• 40:54
  Speaker 1: Let's stick to maybe one particle. Like The classic example
• 40:57
  Speaker 1: of a of a quantum particle is like if I
• 40:59
  Speaker 1: s an electron at a magnetic electric field, is it
• 41:02
  Speaker 1: going to veer to the right or is it going
• 41:04
  Speaker 1: to veer.
• 41:05
  Speaker 2: To the left.
• 41:06
  Speaker 1: Now, in the past, I don't know whether it's going
• 41:08
  Speaker 1: to be veering to the right or to the left.
• 41:10
  Speaker 1: But then I shoot it at the electric field and
• 41:13
  Speaker 1: the particle goes right or left. Now I'm in the future,
• 41:16
  Speaker 1: and the particle went right.
• 41:18
  Speaker 2: Because you collapse the wave function by insisting on measuring
• 41:21
  Speaker 2: it with a classical object. Let's change your experiment a
• 41:24
  Speaker 2: little bit. Let's say you shoot the electron into the
• 41:26
  Speaker 2: magnetic field, but you don't measure which direction it went
• 41:29
  Speaker 2: With some big classical thing like a detector or an
• 41:32
  Speaker 2: eyeball or a graduate student, you record whether it went
• 41:35
  Speaker 2: left or right. Into some other quantum object. You know
• 41:37
  Speaker 2: another particle or photon or something.
• 41:40
  Speaker 1: But I reject your scenario, Daniel. I reject your scenario,
• 41:43
  Speaker 1: and I want to stick to my scenario. In my scenario,
• 41:48
  Speaker 1: there's a future which is the wind right that I
• 41:51
  Speaker 1: couldn't know in the past.
• 41:52
  Speaker 2: Yeah.
• 41:53
  Speaker 1: And if I'm in the future and I saw that
• 41:56
  Speaker 1: the particle went right, I can still sort of figure
• 41:58
  Speaker 1: out where the particle came from. So it just sort
• 42:00
  Speaker 1: of seems like there is a direction to time. In
• 42:03
  Speaker 1: the past, I couldn't tell the future, but in the
• 42:05
  Speaker 1: future I could tell the past.
• 42:07
  Speaker 2: Yes, if there's wave function collapse.
• 42:08
  Speaker 1: Which there was in this scenario.
• 42:11
  Speaker 2: Which violates a basic principle quantum mechanics loss of information,
• 42:15
  Speaker 2: then yes, the future is different from the past because
• 42:17
  Speaker 2: the collapse makes the future different. If you don't believe
• 42:20
  Speaker 2: in collapse, because it's fundamentally nonsense, then your whole premise,
• 42:24
  Speaker 2: then the whole setup is flawed.
• 42:26
  Speaker 1: But I have to believe in collapse because I live
• 42:28
  Speaker 1: in a collapse world. Like when I'm talking to you,
• 42:30
  Speaker 1: I'm collapsing things. You don't know that, man grab my
• 42:33
  Speaker 1: steering wheel. My experience. Maybe there's a multiverse somebody else
• 42:38
  Speaker 1: does something else But to me, in this multiverse version,
• 42:43
  Speaker 1: there's collapse. It's a real thing. And so is there
• 42:46
  Speaker 1: a direction of time in my universe?
• 42:50
  Speaker 2: Well, if there's a multiverse, then the wave function doesn't collapse.
• 42:53
  Speaker 2: It splits in the many pieces. They're all part of
• 42:56
  Speaker 2: the same big universe wave function, but they can't interact
• 42:59
  Speaker 2: with each other, and that preserves the flow of quantum information.
• 43:03
  Speaker 2: All those things do happen, they're just sort of like
• 43:05
  Speaker 2: happening on top of each other in a way that
• 43:06
  Speaker 2: they can't interact with each other. It's the quantum multiverse.
• 43:10
  Speaker 2: So there is a scenario in which there is no
• 43:12
  Speaker 2: collapse and quantum information is not changed as time goes on.
• 43:16
  Speaker 1: Sure, if you're like a mega entity, then you can
• 43:18
  Speaker 1: see all the multiverse at the same time. But to me,
• 43:21
  Speaker 1: to us right now talking to each other, we live
• 43:23
  Speaker 1: in a collapse universe. This is our universe, and we
• 43:25
  Speaker 1: don't even know if there are other universes. So does
• 43:28
  Speaker 1: that mean that time does have a direction? Just make
• 43:31
  Speaker 1: it about me, Daniel, not the watcher who's watching the
• 43:35
  Speaker 1: multiverse from afar.
• 43:37
  Speaker 2: I think portions of the universe no longer have access
• 43:40
  Speaker 2: to the full information. That doesn't mean that time couldn't
• 43:44
  Speaker 2: flow backwards, right, the same physical process could still go
• 43:47
  Speaker 2: in the other direction.
• 43:48
  Speaker 1: Well, it could, But to us, to our understanding and
• 43:52
  Speaker 1: our experience of the universe, this is all the information
• 43:55
  Speaker 1: that we have, and you don't know if there's actually
• 43:57
  Speaker 1: other information.
• 43:58
  Speaker 2: Yeah, we don't know that's true.
• 44:00
  Speaker 1: So we have to assume that this is maybe all
• 44:02
  Speaker 1: there is. This could be all that there is.
• 44:04
  Speaker 2: We don't have to assume that.
• 44:07
  Speaker 1: If you assume it is not all there is to
• 44:09
  Speaker 1: our experience of the universe. In this universe we live in,
• 44:12
  Speaker 1: there is a direction of time.
• 44:13
  Speaker 2: If you don't have the full information, you might not
• 44:16
  Speaker 2: have enough information to reconstruct the past.
• 44:18
  Speaker 1: Yeah, okay, so then is that what do you think
• 44:21
  Speaker 1: Trevor means by things moving backwards in time? Like, could
• 44:25
  Speaker 1: there be something moving in the opposite direction of this
• 44:29
  Speaker 1: direction of time?
• 44:30
  Speaker 2: I don't think that's what Trevor is asking about at all,
• 44:32
  Speaker 2: and he's probably wondering, like why these guys talking about
• 44:34
  Speaker 2: quantum mechanics I was thinking about. So let's get to time.
• 44:39
  Speaker 1: Okay, Well, let's get to this question. The question is
• 44:41
  Speaker 1: can something move backwards in time?
• 44:42
  Speaker 2: Yeah?
• 44:43
  Speaker 1: And would we notice you're the one who went into
• 44:45
  Speaker 1: quantum mechanics. I mean, or are we not answering the
• 44:47
  Speaker 1: question with quantum mechanics or are we no, we're not,
• 44:50
  Speaker 1: We're not so okay.
• 44:53
  Speaker 2: That was a stepping stone towards the concept of thermodynamics,
• 44:56
  Speaker 2: which builds up from the microscopic picture of quantum mechanics.
• 44:59
  Speaker 2: It says, zoom out from the tiny particles. Our experience
• 45:02
  Speaker 2: is not of tiny particles. It's of big things with
• 45:05
  Speaker 2: ten to the twenty nine or ten to the thirty particles.
• 45:07
  Speaker 2: And on that scale something else emerges, and it's called entropy.
• 45:11
  Speaker 2: You have lots of quantum particles interacting. You notice that
• 45:14
  Speaker 2: they tend to spread out over the possibilities, which is
• 45:17
  Speaker 2: another way basically saying entropy increases as time goes on.
• 45:21
  Speaker 2: And that's where our experience of time comes from. What
• 45:23
  Speaker 2: you were alluding to earlier. Like a bouncing ball bouncing
• 45:26
  Speaker 2: up and down, that's a lot of particles interacting. What
• 45:29
  Speaker 2: happens there is that energy tends to spread out, and
• 45:31
  Speaker 2: the ball loses some energy and it bounces lower and
• 45:34
  Speaker 2: lower as time goes on. So that video you could
• 45:37
  Speaker 2: definitely tell if something going forwards or backwards in time.
• 45:40
  Speaker 1: I see you're saying, let's not think about quantity physics.
• 45:43
  Speaker 1: Let's start think about a bouncing ball. And so maybe
• 45:46
  Speaker 1: in Trevor's question, something moving backwards in time is maybe
• 45:50
  Speaker 1: like a ball whose entropy to us seems to be decreasing.
• 45:54
  Speaker 2: Yes, exactly, there's a sort of a subtlety hear like,
• 45:56
  Speaker 2: take that ball that's bouncing and entropy is increasing. You
• 45:59
  Speaker 2: could all say, well, how do we know that ball
• 46:01
  Speaker 2: is not going backwards in time with decreasing entropy. You're like, well,
• 46:04
  Speaker 2: that's just sort of like definitional. Is it moving forwards
• 46:07
  Speaker 2: in time with its entropy increasing, or is it moving
• 46:09
  Speaker 2: backwards in time with its enterpy decreasing. It's basically the
• 46:12
  Speaker 2: same thing. I think what he's asking about. And the
• 46:14
  Speaker 2: original comment that inspired this is that we don't see
• 46:18
  Speaker 2: things moving forwards in time with their entropy decreasing, Like
• 46:22
  Speaker 2: we don't see coffee cups reassembling themselves, we don't see
• 46:27
  Speaker 2: ice freezing on the countertop. All these things would have
• 46:30
  Speaker 2: entropy decreasing, and that's what it would look like. It's
• 46:33
  Speaker 2: to see something moving backwards in time, because we would
• 46:36
  Speaker 2: be moving backwards in time with its entropy increasing. Backwards
• 46:40
  Speaker 2: in time, which to us would look like it's moving
• 46:42
  Speaker 2: forwards in time with its entropy decreasing.
• 46:45
  Speaker 1: So then the answer to the question is that if
• 46:47
  Speaker 1: something was moving backwards in time in our world, which
• 46:50
  Speaker 1: is moving forwards that you're saying, we would be able
• 46:52
  Speaker 1: to notice that it is moving backwards in time because
• 46:54
  Speaker 1: its entropy would be decreasing.
• 46:57
  Speaker 2: Yeah, and I don't remember, but that probably happened in Tenant, right,
• 47:01
  Speaker 2: somebody moved backwards in time and dropped a coffee cup,
• 47:03
  Speaker 2: and to the people moving forwards in time, it looked
• 47:06
  Speaker 2: really weird because they saw a broken coffee cup jump
• 47:09
  Speaker 2: up off the floor and reassemble itself.
• 47:11
  Speaker 1: Yeah. No, no, no, that's exactly. That's the trippy thing
• 47:14
  Speaker 1: about the movies that you see things sort of moving
• 47:17
  Speaker 1: in unnatural ways. Yes, which really to our brain is
• 47:21
  Speaker 1: like you're seeing entropy decrease, which we're not used to.
• 47:24
  Speaker 2: Right, Yeah, exactly, that's what it would look like to
• 47:27
  Speaker 2: see something move backwards in time.
• 47:28
  Speaker 1: Well, I feel like we answered the question, which is like,
• 47:30
  Speaker 1: you know, it's all about entropy, but entropy is not
• 47:33
  Speaker 1: really kind of like a fundamental thing in the universe, right,
• 47:36
  Speaker 1: isn't it sort of like something that emerges from the
• 47:39
  Speaker 1: interaction of lots of things. Like at the quantum level,
• 47:43
  Speaker 1: do you still have entropy and does it play a role?
• 47:45
  Speaker 1: Like let's say we go back to the idea of
• 47:48
  Speaker 1: looking at an electron, could you tell if an electron
• 47:50
  Speaker 1: was moving backwards in time?
• 47:51
  Speaker 2: Yeah, great question. We don't really understand how the air
• 47:54
  Speaker 2: of time emerges. But you're right, it's not something that's
• 47:57
  Speaker 2: fundamental to the universe. It's emergent. But you know, we
• 48:00
  Speaker 2: don't really understand emergence either, like why do laws ever emerge?
• 48:03
  Speaker 2: Why isn't everything just controlled by the tiny little objects
• 48:06
  Speaker 2: and chaos rules? On top of that, we don't understand emergence.
• 48:09
  Speaker 2: We don't understand how time emerges from quantum mechanics. We
• 48:12
  Speaker 2: don't understand the importance of emergent things. There are some
• 48:15
  Speaker 2: hints there and some clues maybe in particle physics, but
• 48:19
  Speaker 2: fundamentally that's not an understood question. You can't even really ask,
• 48:22
  Speaker 2: like what is entropy in quantum mechanics because entropy is
• 48:25
  Speaker 2: about differences and how things are arranged in the macroscopic
• 48:28
  Speaker 2: and the microscopic. You have to like define two levels
• 48:31
  Speaker 2: of information even be talking about entropy.
• 48:35
  Speaker 1: I wonder if then the answer to Trevor's question is, like,
• 48:38
  Speaker 1: you can't do something's moving back to in time unless
• 48:41
  Speaker 1: it's really small, or unless it's only one particle.
• 48:44
  Speaker 2: No, from the one particle, you can't tell at all. Right,
• 48:46
  Speaker 2: there is no sense of entropy for a single particle.
• 48:49
  Speaker 1: That's what I mean. You can't tell. Like a ball,
• 48:51
  Speaker 1: you could tell if it was moving backwards in time,
• 48:53
  Speaker 1: but an individual electron you cannot.
• 48:55
  Speaker 2: Yeah, that's exactly right.
• 48:56
  Speaker 1: So that's what you're saying, unless the multiverse doesn't exist.
• 49:01
  Speaker 2: Yeah, that's right.
• 49:02
  Speaker 1: All right. Well, do you think you need to go
• 49:03
  Speaker 1: back in time and re answer this question?
• 49:06
  Speaker 2: I think I want to go back in time and
• 49:07
  Speaker 2: not bring up quantum mechanics.
• 49:10
  Speaker 1: No, but it totally changes the answer, right, Like if
• 49:12
  Speaker 1: you ignore quantum mechanics, and yes, you can tell something
• 49:14
  Speaker 1: wing backwards in time. If you do things about quantum mechanics,
• 49:18
  Speaker 1: then you can.
• 49:18
  Speaker 4: No.
• 49:18
  Speaker 2: I'm very glad we got into qutum mechanics. That's just you.
• 49:22
  Speaker 1: I think you're always glad to get into quantum mechanics.
• 49:24
  Speaker 1: He has a particle physics. I think the problem sometimes
• 49:28
  Speaker 1: is giving you off of quantum mechanics.
• 49:29
  Speaker 2: Yeah, totally agree.
• 49:30
  Speaker 1: It's a little interesting reversal here. It's like we went
• 49:33
  Speaker 1: backwards in time. All right, Well, thanks to all of
• 49:35
  Speaker 1: our questions askers today, really interesting questions.
• 49:38
  Speaker 2: And if you have questions about how the universe works,
• 49:40
  Speaker 2: please don't be shy right to me to questions at
• 49:43
  Speaker 2: Daniel and Jorge dot com. You can address your questions
• 49:46
  Speaker 2: to me, or to me and Jorge, or to anybody
• 49:47
  Speaker 2: you like. You'll still get an answer from me.
• 49:49
  Speaker 1: We hope you enjoyed that. Thanks for joining us, See
• 49:52
  Speaker 1: you next time.
• 49:57
  Speaker 2: For more science and curiosity. Come fine, get us on
• 50:00
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• 50:08
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