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Speaker 1: Ay, Daniel, what's the most mind blowing thing that physics

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Speaker 1: has taught us about the universe? Wow? It is hard

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Speaker 1: to pick just one. Could I do a top five? Maybe? No?

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Speaker 1: I want your single all time one thing that you

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Speaker 1: think is the most bonkers that we've learned about Who

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Speaker 1: had to challenge? All Right? I got one. There is

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Speaker 1: one thing about the universe that, to me is the

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Speaker 1: most brain scrambling thing I've ever learned. The hardest thing

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Speaker 1: for me to get my brain around is that people

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Speaker 1: can disagree about the order in which events happened. We

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Speaker 1: don't all see the same things happening sometimes in the universe. Yeah,

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Speaker 1: you can see things happening in one order, and then

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Speaker 1: I can see things happening in a totally different order,

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Speaker 1: and we can both be correct. Hi'm poor hammade cartoonists

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Speaker 1: and the creator of PhD Commics. Hi. I'm Daniel. I'm

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Speaker 1: a particle physicist, sometimes in a podcast host other times,

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Speaker 1: and everybody disagrees about when I do what. Welcome to

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Speaker 1: our podcast. Daniel and Jorge agree to disagree about the universe,

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Speaker 1: in which we explained to you the craziest, the most

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Speaker 1: amazing but true things about our universe. Yeah, and this

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Speaker 1: is again a production of I Heart Radio, and in

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Speaker 1: our podcast we try to take you to the forefront

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Speaker 1: of science to talk about the craziest things that scientists

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Speaker 1: are thinking about today, and also delve into the history

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Speaker 1: of science to tell you why we think the universe

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Speaker 1: is so nuts and how we figured that out. Is

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Speaker 1: there a history of science, Daniel, or is that also

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Speaker 1: open for this agreement people disagree about in what order

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Speaker 1: we discover things, or what was the most important, or

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Speaker 1: how we change people's minds. Yeah. I think in our

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Speaker 1: podcast we also not just talk about scientific discoveries or

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Speaker 1: scientific theories, but also a little bit about how that

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Speaker 1: affects how we see the universe, you know, and how

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Speaker 1: it challenges what we believe about how the universe works. Yeah. Absolutely.

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Speaker 1: I think a lot of the deepest questions in physics

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Speaker 1: come from a sort of a philosophical motivation. We want

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Speaker 1: to know how the universe works because it matters to

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Speaker 1: us that we can make sense of the universe. And

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Speaker 1: when we ask the universe questions and it gives us

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Speaker 1: answers that force us to totally change the way we

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Speaker 1: think about the universe. That has pretty deep philosophical implications,

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Speaker 1: and so that's sometimes the most fun topic. Yeah, And

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Speaker 1: so basically, we're just trying to blow your mind in

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Speaker 1: the gentlest, most podcasts friendly way possible. Or we're trying

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Speaker 1: to share with you how the minds of physics this

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Speaker 1: have been blown, and we want your mind to be

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Speaker 1: blown just as much. But yeah, a little bit more gently. Yes, please,

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Speaker 1: I'm not sure my brain can handle this much mind

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Speaker 1: blowing is in in one hour. But you know, when

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Speaker 1: I was learning physics as an undergrad, I remember these

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Speaker 1: moments when I finally really deeply understood a concept, and

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Speaker 1: that concept would force me to relax or destroy or

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Speaker 1: get rid of some assumption I had about the universe,

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Speaker 1: and I realized that that just wasn't true, that the

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Speaker 1: way I'd been thinking about the world was just fundamentally wrong. Yeah,

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Speaker 1: it's amazing. And so today we'll be talking about one

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Speaker 1: such topic that honestly gives me a headache every time

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Speaker 1: we talked about it, Daniel. We've written about it in

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Speaker 1: actually a couple of chapters in our book We Have

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Speaker 1: No Idea, A Guide to the Unknown Universe, And I

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Speaker 1: have to admit I never really got my head around it.

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Speaker 1: I authored the book, but didn't actually understood what was

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Speaker 1: in it. Yeah, and this is a topic that people

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Speaker 1: email us about, they ask us about, they listen to

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Speaker 1: some of our podcasts about it, and still right in

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Speaker 1: with questions. I think there's a lot of popular misconceptions

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Speaker 1: about how this works and some consequences that I think

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Speaker 1: a lot of people have not really realized. There's some

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Speaker 1: really deep philosophical implications to these ideas that I don't

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Speaker 1: think have been widely enough appreciated. Yeah, So to the

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Speaker 1: on the podcast, we'll be talking about how does relativity

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Speaker 1: affect our understanding of time? Time? Or I guess the

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Speaker 1: short title is is there a consistent order of events

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Speaker 1: in the universe? Yeah, and spoiler alert, the answer might

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Speaker 1: be it's relatively surprising that the answer is not what

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Speaker 1: you expect. We've talked to this podcast before about time dilation,

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Speaker 1: the effect of speed on the rate of which clocks

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Speaker 1: move forward, and that's weird and that's hard for people

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Speaker 1: to get their mind around, and there's some misconceptions there.

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Speaker 1: But you know, time and relativity is even weirder than that.

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Speaker 1: It's more than just making things run slowly or making

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Speaker 1: things run quickly. It's about how things happen here versus

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Speaker 1: how things happen there. Do you think age also affects

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Speaker 1: how you perceive time? Like I feel like my kids,

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Speaker 1: I have no patients at all, and that the world

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Speaker 1: just moves at a snail's pace for them, whereas for me,

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Speaker 1: as I get older, things he's moved fast. Well, I

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Speaker 1: mean I moved slower, but the world seems to move fast. Yeah,

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Speaker 1: And I think that Actually you raise an interesting point,

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Speaker 1: because we are all imperfect observers if you just sort

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Speaker 1: of watch something and describe it later. There's all these

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Speaker 1: studies about how people give terrible accounts, you know, even

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Speaker 1: eyewitnesses give different accounts of the same events, And so

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Speaker 1: that's certainly one problem. It's like people are unreliable observers.

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Speaker 1: But even in the case when everybody was a perfect observer,

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Speaker 1: everybody had a video camera, I've already had, you know,

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Speaker 1: perfect measuring devices, and everybody accounted for transmission of light

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Speaker 1: and all that stuff. Even in those cases, it's hard

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Speaker 1: to make sense of the universe. Like if we were

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Speaker 1: all robots but the exact same you know, clock in

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Speaker 1: our chips, and we were all measuring things exactly, we

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Speaker 1: it would still be kind of a weird universe where

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Speaker 1: not everyone would agree maybe on the order of events, Yeah, precisely.

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Speaker 1: And you have to separate those because we're interested not

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Speaker 1: in the question of our people good eyewitnesses, because we

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Speaker 1: already know the answer to that is no um, but

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Speaker 1: the question of how does the universe actually work, because

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Speaker 1: we want to know the answer to the question, not

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Speaker 1: just for humanity, but in general, you know, the deep

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Speaker 1: fundamental questions, so that when the aliens come, when we

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Speaker 1: talk to them about physics, we can make sense of

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Speaker 1: what they've learned. And we don't want to learn human physics,

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Speaker 1: we want to learn fundamental physics. And so this idea

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Speaker 1: of time dilation, this idea that time move slowly depending

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Speaker 1: on maybe how fast you're going or or where you are,

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Speaker 1: is kind of weird and pretty mind blowing. And so

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Speaker 1: we were wondering out there how many people really sort

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Speaker 1: of understood what it means and what the ramification, what

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Speaker 1: it means for our basic understanding of time. So I

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Speaker 1: walked around campus that use the irvine, and I asked folks,

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Speaker 1: not people in the physics department, not people who have

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Speaker 1: taken my class on special relativity, just random people on campus,

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Speaker 1: willing to answer questions from a scrafty looking physicist. So

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Speaker 1: I think for a moment, what do you know about

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Speaker 1: how relativity affects our understanding of time? Here's what people

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Speaker 1: had to say. Do you know how relativity affects our

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Speaker 1: understanding of time? No? I do not. Actually, no, I'm

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Speaker 1: not share Newton's theory of relativity. I'm sorry, I don't.

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Speaker 1: Is this physics like a physics question, I'm not. I

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Speaker 1: don't know much about physics. Okay, I don't know how

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Speaker 1: to answer that. I'm an English Ready, if there was

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Speaker 1: a whole like demonstration of that, where if like you

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Speaker 1: go at like in a spaceship, like near the speed

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Speaker 1: of light or something, and then you can come back

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Speaker 1: and then like some amount of time has changed on

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Speaker 1: Earth while like no, really time has changed for you

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Speaker 1: or somewhere about and thinking Planet of the Apes when

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Speaker 1: they're in the spaceship and then by the time they

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Speaker 1: come back, they've only aged a couple of years, but

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Speaker 1: timeline Earth has passed a lot because they're traveling at

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Speaker 1: a different speed. Remain Planet Apes is a well known

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Speaker 1: physics documentary. Right, yes, yes, I believe relativity. That's from

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Speaker 1: Einstein is the idea that like time doesn't flow at

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Speaker 1: the same rate like across the universe. I think something

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Speaker 1: like I think gravity or something affects like how it

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Speaker 1: flows in other places. All Right, a couple of knows,

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Speaker 1: but a couple of people did have a lot of

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Speaker 1: pretty good ideas, or at least they said a lot

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Speaker 1: of physics terms. And I mean like Newton's theory of relativity,

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Speaker 1: like the Planet of the Apes. You know, I've seen

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Speaker 1: that movie. Yeah, Planet of the Apes. That's a that's

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Speaker 1: a documentary about physics. Yeah, there you go. Now, you're right.

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Speaker 1: People had the people who knew anything about it definitely

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Speaker 1: knew that relativity and time connected and that relativity changes

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Speaker 1: have time moves. And I think already that's a big success, right,

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Speaker 1: the idea that time is not universal, that we don't

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Speaker 1: have clocks everywhere in the universe ticking forward at the

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Speaker 1: same rate. That's a big step forward to to break

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Speaker 1: that assumption. You don't think you didn't have a theory

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Speaker 1: of relativity. I mean he could have had one about

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Speaker 1: his relatives or something, but just not not the one

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Speaker 1: that caught up right. His theory relativity was don't bring

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Speaker 1: up politics at Christmas dinner. Yeah, also also useful things

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Speaker 1: to live by. But yeah, I think it seems like

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Speaker 1: maybe there is a general sense right that relativity effects

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Speaker 1: our understanding of time and makes things weird, but maybe

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Speaker 1: a lot of people don't know how or what. Yeah.

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Speaker 1: And I think also there's a lot of misunderstandings based

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Speaker 1: on the emails that we get from listeners who are

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Speaker 1: asking us questions about relativity and tweets and stuff that

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Speaker 1: people have posted. I have the feeling that people think

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Speaker 1: that if you move fast and your clock will slow down,

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Speaker 1: which is not the right way to think about time

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Speaker 1: and relativity. That's how I thought time and relativity works.

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Speaker 1: So we're in for a long conversation. So, um, so

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Speaker 1: people have been writing with questions about time. Yeah, a

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Speaker 1: lot of people ask the questions like what is it

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Speaker 1: like to be a photon? Or how does a photon

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Speaker 1: move at the speed of light? If moving at the

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Speaker 1: speed of light means that it's time is frozen, they're

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Speaker 1: asking what would be the human experience of moving at

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Speaker 1: these velocities where physics gets really weird. Yeah, and so

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Speaker 1: let's clear that up. First of all, the key thing

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Speaker 1: to understand about relativity and time and clocks. Is that

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Speaker 1: the speed at which o'clock moves depends on its relative

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Speaker 1: velocity to you. Now, these things are always relative. So

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Speaker 1: if you're holding a clock and it's not moving relative

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Speaker 1: to you, it's just going to go forward at one

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Speaker 1: second per second. Like you always experience time the same

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Speaker 1: way because you're not moving relative to yourself. Right, it's

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Speaker 1: all the relative motion that distorts time. If you see

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Speaker 1: a clock moving fast, and you're watching the face of

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Speaker 1: that clock, then it runs slowly, but only according to you.

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Speaker 1: I think maybe we need to step back a little

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Speaker 1: bit paint the picture of Like I'm standing here and

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Speaker 1: I'm holding a clock in front of me. You're saying

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Speaker 1: that because the clock is not moving relative to me,

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Speaker 1: I'm not going to see or feel anything strange about that.

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Speaker 1: That's right. Like it's it's gonna I'm gonna hear it ticking,

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Speaker 1: and I'm gonna it's gonna sound like it's taking at

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Speaker 1: one second. That's right. And you always experience time the

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Speaker 1: same way, Like you don't experience time going slowly or

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Speaker 1: going quickly. But if I'm zipping past you at half

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Speaker 1: the speed of light and I look at your clock,

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Speaker 1: that it looks to me like your clock is running slowly. Now,

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Speaker 1: according to you, the clock is not moving. You're holding it,

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Speaker 1: so the clock runs at the normal pace one second

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Speaker 1: per second like usual. You don't experience time slowing down

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Speaker 1: just because I'm moving past you and I see your

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Speaker 1: time slowing down. But again, if i'm is it being

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Speaker 1: passed you at half the speed of light, then it

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Speaker 1: looks to me like your clock is running slowly. Well,

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Speaker 1: first of all, how would you look at my clock

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Speaker 1: if you were moving back? Remember would you have time? Daniel? Really,

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Speaker 1: I'm super robot observer. Remember I can observe anything accurately. Oh,

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Speaker 1: I see you're running at a basilian giga hurt. I

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Speaker 1: am super physics scratched. No, you have to imagine I

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Speaker 1: have like some awesome telescope and I'm watching the face

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Speaker 1: of your clock or something. All right, So I'm in

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Speaker 1: my little space here and I have my clock, and

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Speaker 1: it's taking away and you're zooming bye. And as you're

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Speaker 1: zooming by, we're going to go into super matrix slow

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Speaker 1: motion and you'r and so you're looking at my clock,

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Speaker 1: and my clock is moving relative to you like you're

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Speaker 1: seeing it go by. And if you were to measure

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Speaker 1: its ticks you, it would to you it would seem

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Speaker 1: like it's ticking slower like tick take right, is that

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Speaker 1: kind of what you mean by that? My clock seems

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Speaker 1: slower to you precisely, and your clock seems slow to me,

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Speaker 1: But it doesn't seem slow to you. Right, It looks

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Speaker 1: to me like you are aging slowly because your time

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Speaker 1: is running slowly. In a year, for me, less time

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Speaker 1: will have passed for you, and I will see you

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Speaker 1: aging slowly. But for you time just moves forward because again,

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Speaker 1: you're not moving relative to you. The thing to remember

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Speaker 1: is moving clocks run slowly, so you're not moving relative

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Speaker 1: to yourself, So your clock doesn't run anymore slowly, but

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Speaker 1: they only move slowly relative to the person who's not moving. Yeah,

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Speaker 1: everybody has a frame of reference that's centered at them,

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Speaker 1: and things are moving or not moving in their frame.

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Speaker 1: And if they're moving fast, then their clocks run slowly.

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Speaker 1: If they're not moving, then their clocks run normally, all right,

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Speaker 1: And that's that's basic general relativity is that time seems

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Speaker 1: to slow down in a pocket of space that's moving

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Speaker 1: fast relative to you. So that's special relativity or relativity

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Speaker 1: has to do with how space is bent by mass.

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Speaker 1: Special relativity is all these effects of light speed and

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Speaker 1: clocks and stuff. And it's not just that it appears

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Speaker 1: to go slowly, like your time really does move slowly

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Speaker 1: according to me. And that's the crux is that I

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Speaker 1: have a story about the universe that I'm telling based

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Speaker 1: on my perfect observations, and that's a true story. And

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Speaker 1: you're telling a different story about the order in which

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Speaker 1: things happened, in the rate at which time flowed, and

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Speaker 1: that's your story. And your story is different because you're

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Speaker 1: in a different place and moving in a different speed

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Speaker 1: relative to me. But both our stories can be correct, meaning, um,

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Speaker 1: I can experience my clock taking it one second per second,

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Speaker 1: but you would say that my clock is not taking

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Speaker 1: it one second per second precisely. And it's not just

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Speaker 1: that it appears that way, it actually is. I guess

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Speaker 1: it depends on what the deffer nition of is. Thank you, Bill.

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Speaker 1: And so you know a lot of people write in

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Speaker 1: they say things like, you know, a photon is moving

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Speaker 1: at the speed of light, which is true. And if

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Speaker 1: a photon had a clock on it, somehow, I don't

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Speaker 1: know how you could have a photon with a clock

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Speaker 1: on it. But imagine you could then wouldn't that clock

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Speaker 1: be frozen? Yes? True, because something moving at the speed

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Speaker 1: of light, it's time slows down to an effective rate

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Speaker 1: of zero. But that doesn't mean that photon is not

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Speaker 1: experiencing time. It's experiencing time maybe normally, but by the

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Speaker 1: time it blinks, it's made it across the whole length

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Speaker 1: of the universe. Yeah, because from the point of view

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Speaker 1: the photon, I guess the whole universe is moving past

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Speaker 1: it at the speed of light, and so the whole

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Speaker 1: universe is like length contracted down to zero. We'll have

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Speaker 1: to do a whole other episode about the effect of

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Speaker 1: relativity on length and distances and crazy stuff like that.

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Speaker 1: But the idea is that moving clocks runs slowly. That's

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Speaker 1: the thing to keep in mind, because all these statements

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Speaker 1: have to be made in a relative sense. You can't

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Speaker 1: say I'm moving really fast, and therefore my clock has

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Speaker 1: run slowly. You have to say I'm moving with fast

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Speaker 1: relative to what. And it's for that observer that your

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Speaker 1: clock is running slowly, not for you, right, Because I'm

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Speaker 1: sitting here in my pocket of space and I'm watching

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Speaker 1: you sit by and if I look at your clock,

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Speaker 1: I would say that your clock is moving slowly, and

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Speaker 1: you would be correct. And I would look at your

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Speaker 1: clock and say your clock is moving slowly and I

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Speaker 1: would be correct. Well, it would be a really short conversation.

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Speaker 1: Then if you're moving past, have dispeeded, like, hey, that

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Speaker 1: well he's gone already, forget it. If this podcast was

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Speaker 1: in stereo, we could do some cool effects. They're resooming

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Speaker 1: back and forth. Make it happen, engineers, you started to

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Speaker 1: treat engineers the same way I have now. Just engineers

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Speaker 1: are just people out there to make things happen. I

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Speaker 1: think people who make things happen are awesome. By the way,

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Speaker 1: my caveat to day engineers. All right, So that's that's

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Speaker 1: special relativity. That's the general idea that, uh, time seems

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Speaker 1: to move totally depending on how fast you're going relative

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Speaker 1: to other people who might be watching your clock. Yeah,

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Speaker 1: I would say time moves slowly for people that are

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Speaker 1: moving fast relative to you. I think that's pretty close

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Speaker 1: to what it's just said. I'm sure it's not. We

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Speaker 1: can disagree on that, all right. So that's special relativity,

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Speaker 1: and it's it creates a weird situation for arguments about

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Speaker 1: what happened and in what order things happen, and just

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Speaker 1: in general um about time and in the universe. So

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Speaker 1: let's get into that, but first let's take a quick break,

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Speaker 1: all right, Daniel, Let's maybe get into the details here

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Speaker 1: of how time or how special relativity messes with our

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Speaker 1: understanding of time. So what what's them? Are we going

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Speaker 1: to paint a picture for people? Are are were gonn

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Speaker 1: to be on trains on rockets? Or Alice and Bob

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Speaker 1: going to be involved? Or yeah, let's let's mix it

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Speaker 1: up a little bit, because usually special relativity is like

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Speaker 1: people on trains, because when they invented special relativity, trains

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Speaker 1: are like the fastest thing around. But that's old and

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Speaker 1: usually quantum mechanics thought experiments involved two experimenters named Alice

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Speaker 1: and Bob. But let's pick it up. Let's use Alice

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Speaker 1: and Bob for a special relativity thought experiment. Let's use

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Speaker 1: Alicia Andrew berta perfect though, just to mix it up,

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Speaker 1: all right, So if um, Alicia and Roberto are having

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Speaker 1: a race, say, it's like some family events right there

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Speaker 1: there with their relatives, so it's all about relativity and

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Speaker 1: they've all had their you know, Christmas Ham or whatever,

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Speaker 1: and now they're going to go out and make an

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Speaker 1: ill advised hundred yard dash in the backyard. And they're

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Speaker 1: both really fast, and people are watching the race, and

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Speaker 1: then afterwards, of course they're going to argue about who one.

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Speaker 1: But let's say that everybody who's watching the race is

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Speaker 1: a perfect observer. Everybody has um a clock that they

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Speaker 1: can start and stop, and everybody's really paying attention and

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Speaker 1: knows what they're doing. Then the question is who wins

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Speaker 1: the race? So they're both at the starting line, you know,

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Speaker 1: we said go, they start running towards the finish line,

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Speaker 1: and I'm sitting there at the finish line waiting to

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Speaker 1: see who gets there first, precisely and all right. The

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Speaker 1: amazing thing is that there is no one, single correct

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Speaker 1: answer for who wins this race. Now, if you're sitting

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Speaker 1: at the finish line, and my money is on Alicia,

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Speaker 1: to be honest, you've always liked her more than Roberto,

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Speaker 1: and frankly, Roberto is pissed about it. Well, she's my cousin,

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Speaker 1: So it's Roberto, man, what's wrong with you? Anyway? Um,

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Speaker 1: if you are sitting at the finish line, so you

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Speaker 1: have um no velocity relative to the ground. Then you

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Speaker 1: might see Alice. You might see Alicia beat Roberto in

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Speaker 1: the race. Cool, and might think, well, that's it, that's

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Speaker 1: the answer, right, she won time to celebrate. So so

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Speaker 1: I'm sitting in a chair by the finish line, and

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Speaker 1: to me, Alicia was running faster than Bob, so she

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Speaker 1: got to the finish line first, precisely, And you might think, well,

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Speaker 1: that's it, right. Other people might see from another angle,

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Speaker 1: or other people might be sitting somewhere differently, or you know,

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Speaker 1: maybe even if somebody is driving by in a car,

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Speaker 1: they might see the velocity of Alicia and Roberto be different.

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Speaker 1: But everybody should agree about the basic facts because there's

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Speaker 1: a single thing that happened. That's the way you grew

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Speaker 1: up thinking about the universe. That's what sort of makes

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Speaker 1: intuitive sense to you. It's true, right, Like if there's

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Speaker 1: somebody sitting on the opposite side of the finish line,

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Speaker 1: sitting in a chair as well, you're saying that they

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Speaker 1: could also see a different result, even if they're not

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Speaker 1: moving like me. Actually, the other observer would have to

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Speaker 1: have a different velocity and you not just be separated

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Speaker 1: in distance. But you're right, The order of events that

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Speaker 1: you see depends on two things. Your location relative to

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Speaker 1: Alicia and Roberto and your speed relative to them. So

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Speaker 1: if you are in a to make it simple, if

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Speaker 1: you are in a car, and your car is super

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Speaker 1: fast and you're going at like half the speed of

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Speaker 1: light or something, then you could see the race differently

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Speaker 1: and you could see you have a different outcome. You

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Speaker 1: could see Roberto cross the finish line before Alicia. This

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Speaker 1: is not some trick where like the life from you

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Speaker 1: takes longer to get there or anything like that. But

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Speaker 1: if you have a different relative distance to Alicia and Roberto,

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Speaker 1: and you're moving at a certain velocity, then you can

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Speaker 1: actually see the events happen in a different order. I

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Speaker 1: am sitting in my chair, I'm going to measure who wins.

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Speaker 1: But if you're moving, driving by at really fast velocities,

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Speaker 1: you might see something totally different than what I see. Yeah,

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Speaker 1: I could see Roberto across the finish line before Alicia,

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Speaker 1: and I would also be right. But do you have

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Speaker 1: to drive towards them perpendicular to them? You know what

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Speaker 1: I mean? Like what's actually happening there to make you

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Speaker 1: see something different? Now, let's imagine It's pretty simple. Let's

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Speaker 1: say I'm moving in the same direction as Alicia and Roberto. Right,

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Speaker 1: you started way before them and or way back, and

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Speaker 1: by the time they cross the finish line, you're crossing

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Speaker 1: the finish line too, but you're going really fast. Right,

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Speaker 1: I started on the moon or something like that, so

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Speaker 1: that I'm passing the race at exactly the same moment

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Speaker 1: that Alicia and Roberto are actually running, so that I'm

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Speaker 1: parallel with them but moving at some very high velocity.

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Speaker 1: Then I can see the order of events differently. I

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Speaker 1: can see the race start, and then I can see

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Speaker 1: Roberto finish the race before Alicia. Even if you sitting

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Speaker 1: on your plastic chair eating leftovers while you're watching sees

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Speaker 1: Alicia passed the finish line first. Yeah, no, I understand

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Speaker 1: that what is maybe happening, But I guess I'm trying

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Speaker 1: to just understand maybe for the people listening to this

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Speaker 1: is why, like, is there any way that we can

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Speaker 1: understand with this example, like how special relativity makes it

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Speaker 1: so that we see different things? Well, special relativity tells

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Speaker 1: you that the flow of time is dependent on velocity, right,

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Speaker 1: and also on distance, So the way the clocks work

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Speaker 1: depends on how far away they are and how fast

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Speaker 1: they are moving. So we talked earlier about how the

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Speaker 1: speed that a clock will move depends on how far

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Speaker 1: how fast it's moving relative to you. That's true, but

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Speaker 1: there's another factor we didn't get into, which is that

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Speaker 1: it also depends on where the clocks are. And so

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Speaker 1: if you see two clocks moving at the same speed

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Speaker 1: relative to you, but there's a distance between them, then

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Speaker 1: you see a different effect on the two clocks. It's

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Speaker 1: not just dependent on the velocity, it's also dependent on

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Speaker 1: the distance to the clocks. Because fundamentally, what's happening is

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Speaker 1: that the universe has sort of like a clock at

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Speaker 1: every location and those and the way those clocks flow

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Speaker 1: depends on your velocity rel tipped to them. Okay, so

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Speaker 1: now you're talking about like a third person. The key

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Speaker 1: thing is this separation between Roberto and Alicia. If Roberto

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Speaker 1: and Alicia are like literally on top of each other,

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Speaker 1: then you don't get this effect. But if there's a

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Speaker 1: gap between that's a different that's a different picture there

429
00:24:17,119 --> 00:24:19,680
Speaker 1: that that doesn't happen in family gatherings. But if there's

430
00:24:19,720 --> 00:24:22,080
Speaker 1: a gap between them, right, if there's a their meter apart,

431
00:24:22,560 --> 00:24:25,359
Speaker 1: five ms apart or something. Then their clocks are going

432
00:24:25,400 --> 00:24:28,119
Speaker 1: to run differently. But how does that affect who I

433
00:24:28,200 --> 00:24:30,919
Speaker 1: see getting to the finish line first? Like, like, it

434
00:24:30,920 --> 00:24:34,840
Speaker 1: shouldn't mattered to me that their clocks are running slower.

435
00:24:35,119 --> 00:24:37,400
Speaker 1: How does that affect how I see them and how

436
00:24:37,440 --> 00:24:39,800
Speaker 1: you would see? Well, if you see if you see

437
00:24:39,800 --> 00:24:43,280
Speaker 1: Alicia's clock running more slowly than Roberto's, then she's got

438
00:24:43,400 --> 00:24:45,199
Speaker 1: not going to be running as fast. I only know

439
00:24:45,240 --> 00:24:47,680
Speaker 1: that they're clocks are running slower because they're moving relative

440
00:24:47,720 --> 00:24:50,600
Speaker 1: to me. So how why imagine that there's a clock

441
00:24:50,640 --> 00:24:54,080
Speaker 1: floating in space next to Alicia and Roberto? Right, So

442
00:24:54,240 --> 00:24:58,040
Speaker 1: some drone robot clock that hangs out right next to them,

443
00:24:58,040 --> 00:25:01,480
Speaker 1: and it can perfectly synchronize it's motion and location relative

444
00:25:01,520 --> 00:25:03,800
Speaker 1: to them to which one one for each of them.

445
00:25:04,000 --> 00:25:07,480
Speaker 1: Then you would see Alicia's clock running at a different

446
00:25:07,560 --> 00:25:10,919
Speaker 1: rate than you see Roberto's clock, because not only do

447
00:25:11,000 --> 00:25:13,000
Speaker 1: they have a velocity relative to you, but there's a

448
00:25:13,040 --> 00:25:15,840
Speaker 1: distance between them. You have a different location, and so

449
00:25:15,920 --> 00:25:18,320
Speaker 1: the way at which time flows depends not just on

450
00:25:18,359 --> 00:25:21,760
Speaker 1: your relative velocity but also where you are relative to

451
00:25:21,760 --> 00:25:23,600
Speaker 1: that observer. All right, So you're saying that I'm going

452
00:25:23,640 --> 00:25:27,440
Speaker 1: to measure. I might measure Alicia or Roberto winning sitting

453
00:25:27,440 --> 00:25:30,280
Speaker 1: by the finish line, but as somebody else you on

454
00:25:30,359 --> 00:25:33,920
Speaker 1: your car, running towards the race at an at an

455
00:25:33,920 --> 00:25:36,800
Speaker 1: angle maybe, or going at a certain speed closest speed

456
00:25:36,840 --> 00:25:40,720
Speaker 1: of light, you might see something different than what I see. Precisely,

457
00:25:41,240 --> 00:25:44,000
Speaker 1: if you are sitting there and you have no velocity

458
00:25:44,040 --> 00:25:46,560
Speaker 1: relative to the ground, maybe you see them tie because

459
00:25:46,560 --> 00:25:48,960
Speaker 1: they've been training forever and they've been working on this,

460
00:25:49,000 --> 00:25:52,119
Speaker 1: and they're both really really fast. But then if I

461
00:25:52,200 --> 00:25:55,280
Speaker 1: am zipping past in a car or moving really fast,

462
00:25:55,800 --> 00:25:59,639
Speaker 1: then I could see Alicia reached the finish line before Bob.

463
00:25:59,720 --> 00:26:02,080
Speaker 1: Reach is the finish line. And you know, it's tricky

464
00:26:02,119 --> 00:26:05,119
Speaker 1: when you're thinking about special relativity. It's really easy to

465
00:26:05,119 --> 00:26:07,840
Speaker 1: get yourself confused. But the most the cleanest way to

466
00:26:07,840 --> 00:26:10,080
Speaker 1: think about it is in terms of events and when

467
00:26:10,080 --> 00:26:14,399
Speaker 1: those events happen. And so you see Alicia reached the

468
00:26:14,400 --> 00:26:17,320
Speaker 1: finish line before Roberto. Now you might think, how is

469
00:26:17,320 --> 00:26:20,120
Speaker 1: that possible, Like they're running at the same speed. Well,

470
00:26:20,160 --> 00:26:22,000
Speaker 1: you know, it's there's also a question of did you

471
00:26:22,040 --> 00:26:25,920
Speaker 1: see them leave the starting point at the same moment? Right,

472
00:26:25,960 --> 00:26:28,560
Speaker 1: because if you're moving at a high speed relative to

473
00:26:28,600 --> 00:26:31,880
Speaker 1: the race, then time is distorted for you, your your

474
00:26:31,960 --> 00:26:34,600
Speaker 1: view of their time is distorted. So you're saying that

475
00:26:34,680 --> 00:26:36,960
Speaker 1: it has to do a little bit with the idea

476
00:26:37,040 --> 00:26:39,680
Speaker 1: that time for Alicia and Roberta are going to be

477
00:26:39,800 --> 00:26:43,520
Speaker 1: moving differently relative to me and to you, and so

478
00:26:43,600 --> 00:26:45,879
Speaker 1: that's going to affect kind of how what we see

479
00:26:46,160 --> 00:26:49,920
Speaker 1: who we see crossing the line. First, precisely, if you

480
00:26:49,960 --> 00:26:52,399
Speaker 1: are sitting there in a plastic chair, finishing your dinner

481
00:26:52,440 --> 00:26:54,760
Speaker 1: and watching Alicia and Roberto across the finish line at

482
00:26:54,800 --> 00:26:57,560
Speaker 1: the same moment, and you see their clocks moving at

483
00:26:57,560 --> 00:26:59,919
Speaker 1: the same speed, and you see them also starting their

484
00:27:00,080 --> 00:27:02,400
Speaker 1: race at the same moment, right, I think maybe that's

485
00:27:02,440 --> 00:27:05,719
Speaker 1: the key insight, whereas you maybe saw them start at

486
00:27:05,720 --> 00:27:08,480
Speaker 1: different times. Yeah, I see Roberto win, but might also

487
00:27:08,480 --> 00:27:11,399
Speaker 1: look to me like Roberto cheated, like he left the

488
00:27:11,480 --> 00:27:14,320
Speaker 1: starting point at a different moment. Right. This concept of

489
00:27:14,400 --> 00:27:17,840
Speaker 1: simultaneity of things happening at the same moment depends on

490
00:27:17,920 --> 00:27:21,080
Speaker 1: your relative speed to those events and your distance from them.

491
00:27:21,200 --> 00:27:25,800
Speaker 1: So like in the Jorge Olympics Backyard Olympics um, Alicia

492
00:27:25,840 --> 00:27:30,320
Speaker 1: would win, but in the Daniel moving at the really

493
00:27:30,359 --> 00:27:34,080
Speaker 1: in a really fast car Olympics, somebody else, not only

494
00:27:34,280 --> 00:27:37,280
Speaker 1: would they, somebody else would win, but somebody else would

495
00:27:37,280 --> 00:27:39,920
Speaker 1: have cheated. Yeah, but you know, according to me, they've

496
00:27:39,960 --> 00:27:41,919
Speaker 1: cheated it. According to you they haven't. And then we

497
00:27:41,960 --> 00:27:45,119
Speaker 1: have a third cousin, you know, um, and she is

498
00:27:45,200 --> 00:27:49,280
Speaker 1: driving her even faster car the other direction, right than that,

499
00:27:49,440 --> 00:27:53,359
Speaker 1: different religio velocity can cause a different distortion of how

500
00:27:53,440 --> 00:27:57,200
Speaker 1: time works from her perspective, and she could see Alicia

501
00:27:57,320 --> 00:28:00,680
Speaker 1: totally blow Roberto away instead of just winning by little bit. Well,

502
00:28:00,680 --> 00:28:02,040
Speaker 1: I think at the end of the day, you know,

503
00:28:02,080 --> 00:28:03,760
Speaker 1: you're going to be by the time they finished, you're

504
00:28:03,760 --> 00:28:06,399
Speaker 1: going to be, you know, hundreds of thousands of miles away,

505
00:28:06,520 --> 00:28:09,200
Speaker 1: And so who cares? What do you think? And if

506
00:28:09,200 --> 00:28:12,280
Speaker 1: you think they cheated, it's how I would put it.

507
00:28:12,280 --> 00:28:14,440
Speaker 1: Whereas I'm right there with the metals ready to hand

508
00:28:14,480 --> 00:28:16,920
Speaker 1: them out, you know, precisely, yea. So in the end,

509
00:28:17,200 --> 00:28:19,200
Speaker 1: your point of view is most important because you're handing

510
00:28:19,200 --> 00:28:22,359
Speaker 1: out the trophies. But the point is that the folks

511
00:28:22,400 --> 00:28:24,800
Speaker 1: in the car driving past on high speeds, they see

512
00:28:24,960 --> 00:28:28,040
Speaker 1: different order of events, and they're not wrong. It's not

513
00:28:28,119 --> 00:28:30,520
Speaker 1: like they messed it. Up because they're moving fast, or

514
00:28:30,560 --> 00:28:32,959
Speaker 1: it took light more time to get to them, or

515
00:28:33,000 --> 00:28:35,679
Speaker 1: any sort of trick like that. If we're assuming perfect

516
00:28:35,800 --> 00:28:39,400
Speaker 1: robotic observers, they just see the order of events differently

517
00:28:39,400 --> 00:28:42,960
Speaker 1: because time is moving differently according to them, and their

518
00:28:43,040 --> 00:28:46,000
Speaker 1: account doesn't have to be wrong. It's just different, just

519
00:28:46,120 --> 00:28:48,760
Speaker 1: like the astronaut or the or just like the photon.

520
00:28:48,880 --> 00:28:50,880
Speaker 1: It's not like the photon is wrong. It's just that

521
00:28:50,920 --> 00:28:56,520
Speaker 1: they experience things differently because they're moving at a different speed. Right,

522
00:28:56,800 --> 00:28:58,640
Speaker 1: And you know, we as humans grew up in a

523
00:28:58,680 --> 00:29:01,760
Speaker 1: world where things move pretty slowly, and so we can

524
00:29:01,840 --> 00:29:05,680
Speaker 1: in the end reconcile usually a single series of events

525
00:29:05,720 --> 00:29:08,320
Speaker 1: like this happened, then that happened, then this other thing happened.

526
00:29:08,520 --> 00:29:11,240
Speaker 1: And sometimes it's hard to disentangle people's emotions and they're

527
00:29:11,480 --> 00:29:14,960
Speaker 1: bad eyewitnesses. But you know, if we had video cameras

528
00:29:14,960 --> 00:29:17,920
Speaker 1: that everybody's location, usually we can disentangle this stuff. But

529
00:29:18,000 --> 00:29:19,800
Speaker 1: as you get next to the speed of light, as

530
00:29:19,840 --> 00:29:23,040
Speaker 1: you get things moving really quickly, then that breaks down

531
00:29:23,360 --> 00:29:25,520
Speaker 1: and time flows differently in such a way that it

532
00:29:25,560 --> 00:29:28,720
Speaker 1: could actually change this order, which means that people have

533
00:29:28,760 --> 00:29:31,960
Speaker 1: a different account of what happened first, and what happened second?

534
00:29:32,000 --> 00:29:34,719
Speaker 1: And I remember the moment in my you know, junior

535
00:29:34,880 --> 00:29:37,240
Speaker 1: special relativity class when I learned this. It just blew

536
00:29:37,280 --> 00:29:40,520
Speaker 1: my mind that there's not like a universally agreed upon

537
00:29:40,800 --> 00:29:44,080
Speaker 1: order of events for stuff happening. But mostly we would

538
00:29:44,080 --> 00:29:46,800
Speaker 1: be all right, we would be or I don't, I

539
00:29:46,800 --> 00:29:48,960
Speaker 1: don't want to say disagreeing, but we would be seeing

540
00:29:49,000 --> 00:29:54,200
Speaker 1: different things. But that usually sort of happens more prominently

541
00:29:54,520 --> 00:29:56,440
Speaker 1: when you get closer to the speed of light. Yeah,

542
00:29:56,480 --> 00:29:59,560
Speaker 1: you can't notice these effects at slow speeds, even for

543
00:29:59,600 --> 00:30:03,440
Speaker 1: the Examp Bowl of Alicia Roberto. If they're running at

544
00:30:03,520 --> 00:30:06,280
Speaker 1: fairly low speeds, you know, ten per second, which actually

545
00:30:06,280 --> 00:30:09,120
Speaker 1: pretty fast, and they're running only a hundred you'd have

546
00:30:09,200 --> 00:30:12,320
Speaker 1: to be going really fast to change the order of

547
00:30:12,400 --> 00:30:15,640
Speaker 1: events by even nano seconds. So these effects are very

548
00:30:15,640 --> 00:30:19,560
Speaker 1: small unless you're approaching the speed of light. Yeah, okay, Yeah,

549
00:30:19,560 --> 00:30:22,560
Speaker 1: it's not like Roberto can argue that he should have

550
00:30:22,560 --> 00:30:26,239
Speaker 1: gone in the metal, because the likelihood that there's an

551
00:30:26,240 --> 00:30:28,560
Speaker 1: observer going to near the speed of light near my

552
00:30:28,640 --> 00:30:33,200
Speaker 1: backyard is um maybe not zero, but unlikely. Well, it

553
00:30:33,200 --> 00:30:35,200
Speaker 1: depends on who's listening to his argument. I might be

554
00:30:35,240 --> 00:30:37,000
Speaker 1: more sympathetic to it. I might be like, you know,

555
00:30:37,040 --> 00:30:39,560
Speaker 1: you're right, Roberto, there is some universe in which you

556
00:30:39,800 --> 00:30:42,640
Speaker 1: did win this and you were jilted from getting the metal. Yeah,

557
00:30:42,680 --> 00:30:44,760
Speaker 1: but really you would be like, yes, Robert, but I

558
00:30:44,760 --> 00:30:50,160
Speaker 1: think you're and then you'd be gone. Daniel thinks you

559
00:30:50,200 --> 00:30:52,960
Speaker 1: won and he's your medal, but he's now by Alpha centauri,

560
00:30:53,080 --> 00:30:56,320
Speaker 1: so you're out of yea, So so go catch up

561
00:30:56,320 --> 00:30:59,560
Speaker 1: if you want your your metal. All right, that's pretty mine,

562
00:30:59,600 --> 00:31:02,440
Speaker 1: bend sing um that so many things can be happening

563
00:31:02,440 --> 00:31:04,200
Speaker 1: in my in my backyard, or that I have new

564
00:31:04,200 --> 00:31:07,760
Speaker 1: cousins called Alicia and Roberto. But let's talk about now

565
00:31:07,920 --> 00:31:10,719
Speaker 1: whether you know how that makes any sense or how

566
00:31:10,800 --> 00:31:14,920
Speaker 1: physicists are able to wrap their heads around these kinds

567
00:31:14,920 --> 00:31:30,800
Speaker 1: of things. But first let's take a quick break, all right, Daniel,

568
00:31:30,840 --> 00:31:36,720
Speaker 1: So according to physics, my backyard Olympics are totally arbitrary,

569
00:31:36,880 --> 00:31:40,800
Speaker 1: meaning that to me they the outcome might be one thing,

570
00:31:40,800 --> 00:31:42,680
Speaker 1: but to you, moving at close to the speed of light,

571
00:31:42,720 --> 00:31:46,080
Speaker 1: the outcome might be different. And you're saying that this

572
00:31:46,360 --> 00:31:50,320
Speaker 1: really throws into question this idea of simultaneity in the universe,

573
00:31:50,360 --> 00:31:53,200
Speaker 1: Like things happening at the same time, because things happening

574
00:31:53,200 --> 00:31:57,000
Speaker 1: at the same time might depend on who's measuring whether

575
00:31:57,080 --> 00:31:59,160
Speaker 1: they happen at the same time. And it's a kind

576
00:31:59,200 --> 00:32:00,760
Speaker 1: of thing that we have to do in physics all

577
00:32:00,760 --> 00:32:03,200
Speaker 1: the time, is we think the universe works a certain way,

578
00:32:03,680 --> 00:32:06,640
Speaker 1: and then the universe shows us the Nope, it doesn't,

579
00:32:07,160 --> 00:32:09,840
Speaker 1: and that momentarily throws us for a loop thing. What

580
00:32:10,280 --> 00:32:12,360
Speaker 1: you know, um, you could do the same experiment twice

581
00:32:12,400 --> 00:32:15,600
Speaker 1: and get different outcomes because quantum mechanics is really probabilistic,

582
00:32:15,720 --> 00:32:19,040
Speaker 1: or you know, time doesn't work the same way for everybody.

583
00:32:19,080 --> 00:32:20,800
Speaker 1: But we don't give it up. We don't say the

584
00:32:20,880 --> 00:32:23,600
Speaker 1: universe therefore makes no sense. What we do is we

585
00:32:23,640 --> 00:32:27,600
Speaker 1: sort of retreat to a looser sense of what sense means.

586
00:32:27,680 --> 00:32:30,520
Speaker 1: We said, all right, we can't make those assumptions. What

587
00:32:30,640 --> 00:32:34,160
Speaker 1: assumptions can we make? What can we say about the universe,

588
00:32:34,360 --> 00:32:36,400
Speaker 1: and we find another way for it to make sense.

589
00:32:36,600 --> 00:32:39,719
Speaker 1: They sort of don't make sense in the sort of

590
00:32:39,760 --> 00:32:43,760
Speaker 1: like Newtonian you know, high school physics or you know

591
00:32:43,800 --> 00:32:46,280
Speaker 1: what we learned as babies how the world works. It

592
00:32:46,320 --> 00:32:49,000
Speaker 1: doesn't make sense in that way, just like maybe quantum

593
00:32:49,040 --> 00:32:52,640
Speaker 1: mechanics doesn't make sense to us, but it does make

594
00:32:52,680 --> 00:32:55,920
Speaker 1: sense if you sort of expand and you understand the

595
00:32:56,120 --> 00:32:58,600
Speaker 1: sort of the equations that are happening. Yeah, Like in

596
00:32:58,680 --> 00:33:02,360
Speaker 1: quantum mechanics, you can't say that the universe is deterministic.

597
00:33:02,440 --> 00:33:04,440
Speaker 1: You can't say that if you do, if you shoot

598
00:33:04,440 --> 00:33:07,280
Speaker 1: an electron at the same atom in exactly the same way,

599
00:33:07,320 --> 00:33:10,360
Speaker 1: you'll get the same outcome every time. You won't because

600
00:33:10,400 --> 00:33:12,880
Speaker 1: there's a randomness there. But what you can do is

601
00:33:12,920 --> 00:33:15,280
Speaker 1: you can say that there are still laws of physics,

602
00:33:15,440 --> 00:33:18,640
Speaker 1: and those laws of physics determine which random outcomes are

603
00:33:18,640 --> 00:33:20,760
Speaker 1: more likely or less likely. So you've sort of taken

604
00:33:21,080 --> 00:33:23,400
Speaker 1: a step backwards. You said, well, I can determine a

605
00:33:23,440 --> 00:33:26,760
Speaker 1: specific outcome, but I can say something about the distribution

606
00:33:26,800 --> 00:33:29,480
Speaker 1: of outcomes, and you can do something sort of similar

607
00:33:29,960 --> 00:33:32,000
Speaker 1: for relativity. You can take a step back and you

608
00:33:32,080 --> 00:33:35,440
Speaker 1: can say, well, I can't say that everybody has to

609
00:33:35,480 --> 00:33:38,760
Speaker 1: agree about the order in which things happen in the universe. Okay,

610
00:33:38,760 --> 00:33:41,640
Speaker 1: what can I say instead? Well, you can say that

611
00:33:41,720 --> 00:33:46,320
Speaker 1: everybody sees things happening according to the same laws. So

612
00:33:47,080 --> 00:33:49,320
Speaker 1: you know, you sitting in your plastic chair at the

613
00:33:49,520 --> 00:33:52,880
Speaker 1: edge of the finish line, you see things happening according

614
00:33:52,920 --> 00:33:55,360
Speaker 1: to a certain laws, set of laws of physics. Me

615
00:33:55,440 --> 00:33:58,600
Speaker 1: and my high speed Lamborghini, I see things happening according

616
00:33:58,640 --> 00:34:01,160
Speaker 1: to the same laws of physics. Now I see different

617
00:34:01,160 --> 00:34:04,400
Speaker 1: things happening, but they're following the same laws. Right, You're

618
00:34:04,400 --> 00:34:09,040
Speaker 1: basically saying that the laws of the universe account for

619
00:34:09,600 --> 00:34:13,560
Speaker 1: this difference of point of view in order of events,

620
00:34:14,000 --> 00:34:16,640
Speaker 1: and so then it makes sense. It's like you're saying

621
00:34:17,239 --> 00:34:19,720
Speaker 1: the laws of physics don't make sense, and that makes sense.

622
00:34:21,000 --> 00:34:24,320
Speaker 1: They make a different sense. They don't make common sense,

623
00:34:24,560 --> 00:34:27,880
Speaker 1: but they make mathematically, they certainly don't make common sense.

624
00:34:28,200 --> 00:34:30,800
Speaker 1: Now it means that you can use the same laws

625
00:34:30,880 --> 00:34:33,439
Speaker 1: to predict what's going to happen. Is I can use

626
00:34:33,680 --> 00:34:35,719
Speaker 1: in my frames. So no matter how fast you're going

627
00:34:35,719 --> 00:34:37,400
Speaker 1: and where you are in the universe, you should be

628
00:34:37,400 --> 00:34:39,680
Speaker 1: able to use the same laws to describe what you

629
00:34:39,719 --> 00:34:42,000
Speaker 1: see and to predict what's going to happen, and those

630
00:34:42,080 --> 00:34:45,040
Speaker 1: laws should work. So we can still make that requirement.

631
00:34:45,480 --> 00:34:47,560
Speaker 1: The events can be different from place to place. In

632
00:34:47,600 --> 00:34:50,160
Speaker 1: the description of what happened can be different from place

633
00:34:50,200 --> 00:34:53,960
Speaker 1: to place, but each one follows the same set of rules. Right,

634
00:34:54,000 --> 00:34:57,279
Speaker 1: there's nothing inconsistent about the universe. It's just that the

635
00:34:57,360 --> 00:35:00,040
Speaker 1: rules of the universe allow for this kind of of

636
00:35:00,719 --> 00:35:03,960
Speaker 1: different points of view depending on your speed precisely, and

637
00:35:04,680 --> 00:35:07,400
Speaker 1: that your point of your direction precisely. And I think

638
00:35:07,440 --> 00:35:09,719
Speaker 1: it's a tiny bit deeper than that. It's not just

639
00:35:09,800 --> 00:35:12,840
Speaker 1: that we understand how to translate what you see to

640
00:35:12,920 --> 00:35:15,759
Speaker 1: what someone else going at high speeds will see. We

641
00:35:15,880 --> 00:35:18,640
Speaker 1: do understand that, and that's cool. But the deeper bit

642
00:35:19,000 --> 00:35:21,760
Speaker 1: is that the same rules apply no matter how fast

643
00:35:21,800 --> 00:35:24,320
Speaker 1: you are going, So you can use the same laws

644
00:35:24,320 --> 00:35:27,200
Speaker 1: of physics. Now, you and I can disagree about the

645
00:35:27,280 --> 00:35:29,279
Speaker 1: order that we saw the race be run and who

646
00:35:29,280 --> 00:35:32,320
Speaker 1: won and who cheated, but we agree on the rules

647
00:35:32,400 --> 00:35:35,600
Speaker 1: of physics that describe what we saw, not just how

648
00:35:35,600 --> 00:35:38,280
Speaker 1: it translates from what I saw to what you saw.

649
00:35:38,520 --> 00:35:40,839
Speaker 1: We see them follow the same rules. And I think

650
00:35:40,880 --> 00:35:43,440
Speaker 1: that's pretty deep. And then there's one more thing that

651
00:35:43,480 --> 00:35:46,880
Speaker 1: we can still cling to. We can say that even

652
00:35:46,960 --> 00:35:49,799
Speaker 1: though things can happen in a different order, sometimes there

653
00:35:49,840 --> 00:35:53,439
Speaker 1: are some rules about that, you can't arbitrarily re order

654
00:35:53,520 --> 00:35:56,200
Speaker 1: the universe. Oh, I see, Yeah, this is what you're

655
00:35:56,360 --> 00:36:01,560
Speaker 1: saying earlier. There's a difference between simultaneity and cold. That's right,

656
00:36:01,760 --> 00:36:08,600
Speaker 1: they're both impossible to pronounce words yeah and clug cool. Obviously,

657
00:36:08,680 --> 00:36:11,040
Speaker 1: if I can reverse the order there of events, I

658
00:36:11,040 --> 00:36:14,920
Speaker 1: would say causality, correct. Yeah. The key thing is that

659
00:36:15,000 --> 00:36:18,600
Speaker 1: you can use velocity and distance and all these crazy

660
00:36:18,640 --> 00:36:22,960
Speaker 1: relativistic effects to reverse the order of some events, events

661
00:36:23,120 --> 00:36:27,040
Speaker 1: that are not causally connected, events where one didn't cause

662
00:36:27,160 --> 00:36:30,440
Speaker 1: the other one. But some things you can't. Mean, we

663
00:36:30,480 --> 00:36:33,840
Speaker 1: can see different outcomes of a race between Alicia and Roberta,

664
00:36:34,320 --> 00:36:39,720
Speaker 1: but we probably wouldn't disagree on a relay raise with Alicia.

665
00:36:39,440 --> 00:36:43,160
Speaker 1: Er yeah, yeah, Or for example, there's no speed at

666
00:36:43,160 --> 00:36:46,320
Speaker 1: which you can go in order to see Alicia finish

667
00:36:46,360 --> 00:36:49,800
Speaker 1: the race before she starts, and that order events definitely happens.

668
00:36:49,800 --> 00:36:52,520
Speaker 1: She starts the race, and then later she finishes. Now

669
00:36:52,560 --> 00:36:56,120
Speaker 1: when she finishes relative to Roberto, that's a different question.

670
00:36:56,239 --> 00:36:58,840
Speaker 1: We can zoom around our spaceships to get whatever answer

671
00:36:58,880 --> 00:37:00,680
Speaker 1: we want, But there's no But you'd have to go

672
00:37:00,800 --> 00:37:03,480
Speaker 1: faster than the speed of light in order to reverse

673
00:37:03,520 --> 00:37:06,440
Speaker 1: two events that are causally connected where one caused the

674
00:37:06,520 --> 00:37:09,319
Speaker 1: other one. So that's why you can't, for example, make

675
00:37:09,360 --> 00:37:11,880
Speaker 1: the Big Bang happened at the end of the universe,

676
00:37:12,040 --> 00:37:14,800
Speaker 1: or you know, all sorts of other crazy stuff. There's

677
00:37:14,880 --> 00:37:17,400
Speaker 1: some freedom here to move around the order of events,

678
00:37:17,440 --> 00:37:20,560
Speaker 1: but it's not pure total freedom. Don't go crazy people.

679
00:37:23,360 --> 00:37:26,960
Speaker 1: Meaning is not that the whole universe is open to interpretation,

680
00:37:27,160 --> 00:37:31,080
Speaker 1: because you know, like, um, the Big Bang happened and

681
00:37:31,280 --> 00:37:34,080
Speaker 1: Earth formed, and it's not like moving at any speed

682
00:37:34,120 --> 00:37:38,200
Speaker 1: will change anything about that. But maybe small things, like

683
00:37:38,239 --> 00:37:40,560
Speaker 1: small things that might some people might say happen or

684
00:37:40,560 --> 00:37:44,359
Speaker 1: not happen simultaneously. Then people moving at different speed might

685
00:37:44,440 --> 00:37:47,320
Speaker 1: have a different point of view. Yeah, And the size

686
00:37:47,360 --> 00:37:49,600
Speaker 1: of these things depends on sort of how far away

687
00:37:49,600 --> 00:37:52,440
Speaker 1: they are, like things that are in another galaxy, they

688
00:37:52,440 --> 00:37:56,080
Speaker 1: are really really far away. Nothing over there is causally

689
00:37:56,120 --> 00:37:59,479
Speaker 1: dependent on anything we do, because nothing we do here

690
00:37:59,600 --> 00:38:03,040
Speaker 1: can acted for a long long time, because you know,

691
00:38:03,239 --> 00:38:05,640
Speaker 1: there's because of the speed of light. So things happening

692
00:38:05,680 --> 00:38:07,640
Speaker 1: on the other side of the universe, you know, the

693
00:38:07,719 --> 00:38:10,600
Speaker 1: order in which those events happen is almost irrelevant for us.

694
00:38:10,600 --> 00:38:13,080
Speaker 1: So we could change those are events by a billion years,

695
00:38:13,120 --> 00:38:16,320
Speaker 1: probably because it makes no difference to the causal connections,

696
00:38:16,320 --> 00:38:19,000
Speaker 1: because nothing that happens here affects that for a very

697
00:38:19,040 --> 00:38:22,799
Speaker 1: long time. Things that are close together, right, it's much

698
00:38:22,840 --> 00:38:26,080
Speaker 1: more sensitive. You can causally affect the things close to you.

699
00:38:26,080 --> 00:38:27,800
Speaker 1: You can touch things, you can push things over, You

700
00:38:27,840 --> 00:38:30,640
Speaker 1: can shine a flashlight and affect things nearby. So you're

701
00:38:30,640 --> 00:38:33,000
Speaker 1: saying that that a raise in the backyard in another

702
00:38:33,040 --> 00:38:38,520
Speaker 1: galaxy could have happened before or after my race, maybe

703
00:38:38,560 --> 00:38:42,000
Speaker 1: because there's a long separation between them. But because they

704
00:38:42,000 --> 00:38:45,960
Speaker 1: don't affect each other, then it's it's okay to sort

705
00:38:45,960 --> 00:38:48,600
Speaker 1: of move them around in terms of our perception of

706
00:38:48,600 --> 00:38:51,640
Speaker 1: when they happen. Yeah, And we talked about this thing

707
00:38:51,680 --> 00:38:55,239
Speaker 1: called the light cone, which is this cone of in

708
00:38:55,360 --> 00:38:57,640
Speaker 1: space that that opens up at the speed of light

709
00:38:57,719 --> 00:39:00,239
Speaker 1: around you. You can only affect things that are in

710
00:39:00,280 --> 00:39:03,720
Speaker 1: your light cone. Things that are sort of downstream from you,

711
00:39:03,719 --> 00:39:06,239
Speaker 1: you can affect them. Those things are causally dependent on

712
00:39:06,320 --> 00:39:09,000
Speaker 1: what you do. Things that are not in your light

713
00:39:09,000 --> 00:39:11,120
Speaker 1: cone that they're too far away from you for you

714
00:39:11,160 --> 00:39:14,160
Speaker 1: to affect them now or in the near future, there's

715
00:39:14,160 --> 00:39:15,839
Speaker 1: no way for you to have any influence over them.

716
00:39:16,000 --> 00:39:18,239
Speaker 1: So their relativity can go crazy and it can change

717
00:39:18,239 --> 00:39:21,600
Speaker 1: the order events without breaking anything. Right, But we're still

718
00:39:21,640 --> 00:39:24,759
Speaker 1: all in the same universe, right, we are all in

719
00:39:24,800 --> 00:39:27,440
Speaker 1: the same universe. Yeah. Yeah, it's not like I'm disconnected

720
00:39:27,480 --> 00:39:30,400
Speaker 1: from that galaxy or things that are not in my

721
00:39:30,480 --> 00:39:32,680
Speaker 1: light cone. Something in my light cone might be in

722
00:39:32,719 --> 00:39:35,480
Speaker 1: that other things like cone, and so I'm sort of

723
00:39:35,480 --> 00:39:37,520
Speaker 1: still connected to the rest of the universe. Yeah, And

724
00:39:37,520 --> 00:39:40,399
Speaker 1: your light cone goes on forever and so eventually will

725
00:39:40,480 --> 00:39:43,200
Speaker 1: encompass the entire universe. Right, things you do now could

726
00:39:43,280 --> 00:39:46,560
Speaker 1: affect things fifteen billion light years away, but it's going

727
00:39:46,600 --> 00:39:49,640
Speaker 1: to take fifteen billion years. So your light cone is growing,

728
00:39:49,640 --> 00:39:53,120
Speaker 1: and eventually everything is like cone overlaps, right, So things

729
00:39:53,160 --> 00:39:55,399
Speaker 1: do come into contact. And I think my ego needs

730
00:39:55,400 --> 00:39:57,560
Speaker 1: any more feeding, Daniel, just to think that I can

731
00:39:57,600 --> 00:40:00,839
Speaker 1: affect the entire universe eventually. That's pretty big step up

732
00:40:00,880 --> 00:40:04,319
Speaker 1: from handing out medals from the backyard backyard Olympics to

733
00:40:04,800 --> 00:40:09,440
Speaker 1: expecting the entire universe. Small steps, my friend, backyard Olympics today,

734
00:40:10,440 --> 00:40:13,440
Speaker 1: galaxy collisions tomorrow. No, I think the thing to understand

735
00:40:13,719 --> 00:40:16,400
Speaker 1: is that we are all living the same universe, and

736
00:40:16,440 --> 00:40:19,279
Speaker 1: that universe has a certain set of rules. But those

737
00:40:19,360 --> 00:40:21,919
Speaker 1: rules are not necessarily the rules you thought they were,

738
00:40:22,360 --> 00:40:25,000
Speaker 1: and it allows for some fudging and some flexibility and

739
00:40:25,040 --> 00:40:27,520
Speaker 1: for some weird stuff to happen. But it's not throwing

740
00:40:27,560 --> 00:40:29,719
Speaker 1: everything out the window. It has to be consistent with

741
00:40:29,840 --> 00:40:31,880
Speaker 1: the you know, the the universe we've lived and the

742
00:40:31,880 --> 00:40:34,680
Speaker 1: things we've observed. You don't get to go really fast

743
00:40:34,719 --> 00:40:36,839
Speaker 1: and go back in time. You don't get to go

744
00:40:36,920 --> 00:40:39,200
Speaker 1: really fast and you know, change your order from a

745
00:40:39,280 --> 00:40:41,880
Speaker 1: chicken sandwich to a burger or whatever. Right. There are

746
00:40:41,920 --> 00:40:44,919
Speaker 1: still rules to the universe. They're just not as hard

747
00:40:44,960 --> 00:40:47,440
Speaker 1: and fast as you thought. And fundamentally it means that

748
00:40:47,440 --> 00:40:49,600
Speaker 1: the universe is different from the one we thought it was.

749
00:40:49,719 --> 00:40:53,000
Speaker 1: You know, the way quantum mechanics has deep implications for

750
00:40:53,080 --> 00:40:55,359
Speaker 1: the way the universe works, but doesn't really change your

751
00:40:55,480 --> 00:40:58,160
Speaker 1: day to day. Right. You if you don't go to work,

752
00:40:58,160 --> 00:41:00,439
Speaker 1: you still lose your job. Right. There are some things

753
00:41:00,440 --> 00:41:03,760
Speaker 1: that are deterministic. We don't fix climate change. The planet

754
00:41:03,800 --> 00:41:07,040
Speaker 1: might get too hot. Right, It's not like we can

755
00:41:07,080 --> 00:41:09,600
Speaker 1: disagree about that. No, And this is not an excuse

756
00:41:09,640 --> 00:41:11,920
Speaker 1: to say that you can have just whatever facts you want, right,

757
00:41:12,400 --> 00:41:15,000
Speaker 1: It's just that the facts are sort of local. Right,

758
00:41:15,360 --> 00:41:17,279
Speaker 1: depending on where you are and how fast you're going.

759
00:41:17,640 --> 00:41:20,280
Speaker 1: Your account of what happened in the universe is different,

760
00:41:20,680 --> 00:41:23,600
Speaker 1: but it's always just blown my mind that people can

761
00:41:23,640 --> 00:41:26,919
Speaker 1: have correct but different accounts of the order in which

762
00:41:26,960 --> 00:41:29,400
Speaker 1: things happened. Although I think one thing that never changes

763
00:41:29,520 --> 00:41:31,400
Speaker 1: is I think Roberto is a cheater. I think he

764
00:41:31,520 --> 00:41:35,799
Speaker 1: cheats in any universe, in any galaxy, and no matter

765
00:41:35,840 --> 00:41:39,040
Speaker 1: who you're looking, I think the question in my mind

766
00:41:39,120 --> 00:41:41,319
Speaker 1: and in listeners minds is do you actually have a

767
00:41:41,320 --> 00:41:43,640
Speaker 1: cousin named Roberto? And if so, does he listen to

768
00:41:43,719 --> 00:41:47,080
Speaker 1: the podcast? Oh my god, I justly do have a

769
00:41:47,120 --> 00:41:52,319
Speaker 1: cousin named Roberto. That's what happened. I don't need to

770
00:41:52,320 --> 00:41:55,719
Speaker 1: say you're a cheater talking about our other cousins. Cousin

771
00:41:55,840 --> 00:41:58,440
Speaker 1: Roberto Prime, and do you have a cousin named Alicia,

772
00:41:58,520 --> 00:42:00,920
Speaker 1: because now she's going to be your favorite. Let me

773
00:42:00,960 --> 00:42:03,480
Speaker 1: think I don't have a cousin name. Let me think

774
00:42:03,520 --> 00:42:08,560
Speaker 1: who has to say? Let me think, like dozens of cousins,

775
00:42:09,280 --> 00:42:11,480
Speaker 1: so one of the thirty six cousins needs a little

776
00:42:11,520 --> 00:42:13,160
Speaker 1: bit of a second there to think about, where were

777
00:42:13,200 --> 00:42:16,160
Speaker 1: you last night? Honey? Let me think? You know? Never

778
00:42:16,200 --> 00:42:19,680
Speaker 1: a very inspiring answer, especially in Latin American culture, where

779
00:42:19,719 --> 00:42:22,879
Speaker 1: everyone has a nickname that is totally unrelated to their

780
00:42:22,920 --> 00:42:25,200
Speaker 1: actual name. You have to think a little bit. Oh,

781
00:42:25,239 --> 00:42:27,480
Speaker 1: so when you're talking about Roberto, that's actually a nickname

782
00:42:27,560 --> 00:42:31,160
Speaker 1: for your other cousin, Nicholas or something. Yes, that's right,

783
00:42:31,239 --> 00:42:33,080
Speaker 1: something like that. That is how it goes. It sounds

784
00:42:33,120 --> 00:42:35,040
Speaker 1: like a Russian novel. All right. Well, I hope that

785
00:42:35,160 --> 00:42:39,680
Speaker 1: sufficiently altered or bent your mind there for at least

786
00:42:40,320 --> 00:42:42,600
Speaker 1: at the time of this podcast. And remember that the

787
00:42:42,719 --> 00:42:46,200
Speaker 1: university is crazy. The university's bonkers, but it's our universe

788
00:42:46,360 --> 00:42:49,240
Speaker 1: and we love it, and eventually we hope it will

789
00:42:49,280 --> 00:42:51,520
Speaker 1: make sense to us. That's right, just like we love

790
00:42:51,600 --> 00:42:54,120
Speaker 1: that crazy cousin we all have who we now have

791
00:42:54,160 --> 00:42:57,799
Speaker 1: to apologize to after this podcast. Well, nobody listens to

792
00:42:57,800 --> 00:43:01,040
Speaker 1: this podcast, I think so. All right, Thanks everyone for

793
00:43:01,080 --> 00:43:04,400
Speaker 1: listening and for asking us crazy questions. And if you

794
00:43:04,560 --> 00:43:07,279
Speaker 1: still don't understand special relativity in the flow of time,

795
00:43:07,320 --> 00:43:10,320
Speaker 1: don't worry. Nobody else really does either. Thanks for listening.

796
00:43:10,400 --> 00:43:20,440
Speaker 1: See you next time. Before you still have a question

797
00:43:20,480 --> 00:43:23,919
Speaker 1: after listening to all these explanations, please drop us a line.

798
00:43:23,960 --> 00:43:26,120
Speaker 1: We'd love to hear from you. You can find us

799
00:43:26,120 --> 00:43:29,919
Speaker 1: on Facebook, Twitter, and Instagram at Daniel and Jorge. That's

800
00:43:29,920 --> 00:43:33,319
Speaker 1: one word or email us at feedback at Daniel and

801
00:43:33,440 --> 00:43:36,880
Speaker 1: Jorge dot com. Thanks for listening, and remember that Daniel

802
00:43:36,920 --> 00:43:39,400
Speaker 1: and Jorge explained. The Universe is a production of I

803
00:43:39,640 --> 00:43:43,080
Speaker 1: Heart Radio. From more podcast from my heart Radio, visit

804
00:43:43,120 --> 00:43:46,600
Speaker 1: the i heart Radio app, Apple Podcasts, or wherever you

805
00:43:46,719 --> 00:43:48,240
Speaker 1: listen to your favorite shows.