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Speaker 1: Hey, Jorhan Daniel here, and we want to tell you

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Speaker 1: about our new book. It's called Frequently Asked Questions about

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Speaker 1: the Universe because you have questions about the universe, and

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Speaker 1: so we decided to write a book all about them.

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Speaker 1: We talk about your questions, we give some answers, we

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Speaker 1: make a bunch of silly jokes as usual, and we

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Speaker 1: tackle all kinds of questions, including what happens if I

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Speaker 1: fall into a black hole? Or is there another version

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Speaker 1: of you out there that's right? Like usual, we tackle

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Speaker 1: the deepest, darkest, biggest, craziest questions about this incredible cosmos.

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Speaker 1: If you want to support the podcast, please get the

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Speaker 1: book and get a copy, not just for yourself, but

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Speaker 1: you know, for your nieces and nephews, cousins, friends, parents, dogs, hamsters,

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Speaker 1: and for the aliens. So get your copy of Frequently

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Speaker 1: Asked Questions about the Universe is available for pre order now,

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Speaker 1: coming out November two. You can find more details at

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Speaker 1: the book's website, Universe f a Q dot com. Thanks

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Speaker 1: for your support, and if you have a hamster that

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Speaker 1: can read, please let us know. We'd love to have

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Speaker 1: them on the podcast. Hey Daniel, I've noticed something pretty

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Speaker 1: strange about how time works. Oh yeah, you have time

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Speaker 1: to make your own theory of time. Well that's the thing, right, Like,

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Speaker 1: I noticed that time seems to speed up as you

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Speaker 1: get closer to a deadline. That's true. Deadlines seem to

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Speaker 1: be infinitely far in the future, until all of a

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Speaker 1: sudden there on top of you. Right. I think the

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Speaker 1: only thing that can explain it is that time itself

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Speaker 1: bends when it's closed to some procrastination. Well, time does

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Speaker 1: slow down near a massive object, like a black hole.

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Speaker 1: I think maybe I just need less massive deadlines maybe,

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Speaker 1: or maybe your two do list is so dense it's

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Speaker 1: becoming a black hole. Definitely sucks you in. Hi am Jorge.

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Speaker 1: I'm a cartoonist and the creator of PhD comics. Hi

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Speaker 1: I'm Daniel. I'm a particle physicist and a professor you

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Speaker 1: see Irvine, and I'm just part of Jorges to do list.

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Speaker 1: That sounds kind of inappropriate, Daniel, I mean I have

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Speaker 1: to be like Daniel, or have to be Daniel. I

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Speaker 1: mean that I just contribute elements to your to do list. Oh,

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Speaker 1: I see you add to my things to do. I'm

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Speaker 1: on your to do list. But anyways, welcome to our

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Speaker 1: podcast Daniel and Jorge Explain the Universe, a production of

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Speaker 1: My Heart Radio, in which our to do list is

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Speaker 1: to explain the entire universe bit by bit, concept by concept,

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Speaker 1: puzzle by puzzle to you, our wonderful listeners who deeply

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Speaker 1: and desperately want to understand the nature of the universe.

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Speaker 1: We find ourselves in the whole project of physics, starting

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Speaker 1: with ancient man looking up at the sky and extending

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Speaker 1: to the Greeks trying to understand the nature of reality.

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Speaker 1: Ends here on the podcast when we try to break

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Speaker 1: down on the nature of the universe and explain all

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Speaker 1: of it to you and hopefully a timely matter, right,

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Speaker 1: because you know, time is money and money is gravity.

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Speaker 1: Money is dough and everybody needs it. Yeah, sometimes we

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Speaker 1: eat too much dough. But yeah, it is a big,

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Speaker 1: beautiful universe and we like to talk about all the

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Speaker 1: things in it, even time itself, because time is part

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Speaker 1: of the universe. Right. Time is part of the universe

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Speaker 1: that we don't understand. Is it a fundamental element of

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Speaker 1: the universe? Is it something that bubbles up and just

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Speaker 1: sort of appears from other fundamental things like ice cream

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Speaker 1: and lava and hurricanes? Or is it really deeply ingrained?

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Speaker 1: And on this podcast we don't shy away from asking

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Speaker 1: those really big, deep and difficult to grapple with questions,

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Speaker 1: you know, like what is time anyway? How do you

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Speaker 1: even define it? How do you even ask crisp and

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Speaker 1: precise questions about this slipperyst but most essential of concepts. Yeah,

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Speaker 1: because time always seems to slip by you no matter

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Speaker 1: what do you do, and asking these questions, it's not

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Speaker 1: just in ourder to do list, but it's also in

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Speaker 1: our want to do list, right, Daniel, I mean, that's

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Speaker 1: kind of what you're getting, kid. That is what I

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Speaker 1: get paid for, not on a day to day basis,

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Speaker 1: and mostly I'm cracking open particles at the large age

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Speaker 1: on collider, But these are the big goals of physics,

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Speaker 1: is to understand the nature of our experience. You know,

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Speaker 1: some people think physics is sort of like abstract and

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Speaker 1: separated from humanity. But it's taken me a long time

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Speaker 1: to realize that it's the most human of sciences because

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Speaker 1: it asked these questions to the very core of the

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Speaker 1: context of what it's like to be alive. You know,

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Speaker 1: you notice things slipping into the past through this weird

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Speaker 1: instantaneous slice called the present. It's definitely something we'd like

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Speaker 1: to understand. Are you saying, physics out humanities? The humanities?

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Speaker 1: Daniel out philosophies the philosophers. Yeah, you know, I used

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Speaker 1: to think that physics was the most interesting science because

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Speaker 1: it was probably the most fundamental, the most universal, that

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Speaker 1: somehow it escaped humanity, that if aliens came, they wouldn't

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Speaker 1: be interested in our biological advances because they wouldn't be

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Speaker 1: relevant to them, but they would be interested in what

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Speaker 1: we've learned about physics. I'm not so sure about that anymore.

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Speaker 1: And can hear all those mathematicians out they're laughing at

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Speaker 1: you right now. You're like, you're pure, We're the purest,

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Speaker 1: even mathematicians. Man, Mathematics is just codification of the logic

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Speaker 1: and human brains. And I suspect that aliens might not

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Speaker 1: even do math, and if they do, we might not

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Speaker 1: even recognize it. Oh man, you're saying physics supersedes math

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Speaker 1: from a human point of view. Oh boy, we just

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Speaker 1: started in an academic warrior. You just did that. That's

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Speaker 1: not what I'm saying at all. I'm saying that everything

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Speaker 1: we do is based in human thought and contextualized by

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Speaker 1: human questions. But that doesn't make it worthless. It means

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Speaker 1: that we get to ask really interesting questions about what

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Speaker 1: it's like to be alive. Yeah, and so sometimes those

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Speaker 1: questions get into the idea of time itself, because I

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Speaker 1: think maybe most people have a conception of the university's

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Speaker 1: sort of existing outside of time, or like it's a

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Speaker 1: universe moving through time, but actually physicists think of time

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Speaker 1: as part of the universe, right, it's like another thing

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Speaker 1: in it. Yeah, we don't really understand. Physicists like to

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Speaker 1: divide elements of the universe into things that are fundamental,

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Speaker 1: meaning they're like basic, they're essential, they have to be there.

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Speaker 1: They define what the universe is, and then other things

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Speaker 1: that are emergent that sort of come out of the

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Speaker 1: interplay of those fundamental objects. And we don't know if

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Speaker 1: time is fundamental, if it's like absolutely essential it's part

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Speaker 1: of the nature of the universe, or if it bubbles

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Speaker 1: up from something else. We don't know if space and

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Speaker 1: matter sort of sit in a framework of time which

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Speaker 1: is external to them, or if the whole thing is

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Speaker 1: just you know, comes up from some other weird, deep nature.

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Speaker 1: We haven't even imagined, like, is it hard coded into

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Speaker 1: the circuitry of the universe or is it like a

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Speaker 1: program running on top of the chip of the universe

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Speaker 1: that's kind of what you mean, right, Or is it

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Speaker 1: just the way the humans think, you know? It might

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Speaker 1: be that our tendency to think in terms of stories

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Speaker 1: and narratives which have cause and effect, might bias us

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Speaker 1: to see things as flowing forwards in time, when in

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Speaker 1: reality the truth might be much more complex. We just

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Speaker 1: an episode about how causality, cause and effect might not

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Speaker 1: even be an essential element of the universe, and so

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Speaker 1: it might be that time itself could be something that's

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Speaker 1: just sort of very human. Yeah, it's sort of like

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Speaker 1: this podcast. We have no narrative, right, We are just

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Speaker 1: jumping around in time to whatever comes into our minds here.

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Speaker 1: But it's these kind of basic questions that give us

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Speaker 1: a launching off point for asking questions and doing studies

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Speaker 1: and trying to like find a way to grapple with

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Speaker 1: these things scientifically, because we could sit here and smoke

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Speaker 1: man in appeals and talk about the nuture of time

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Speaker 1: forever without making progress. But we want to do experiments.

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Speaker 1: We want to use science to add to our body

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Speaker 1: of actual knowledge about time. Yeah, so we'll be exploring

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Speaker 1: a little bit about this weird concept of time and

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Speaker 1: especially about how time behaves according to our theories about

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Speaker 1: the universe. So today on the podcast, we'll be asking

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Speaker 1: the question why does gravity slow down time? Or should

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Speaker 1: I should I ask it slow down time? Or maybe

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Speaker 1: you should use your gravest voice, you know, your James

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Speaker 1: Earl Jones voice. You're trying to make a gravity joke.

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Speaker 1: That's kind of heavy, man, don't make light of the situation.

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Speaker 1: I'm a massive fan of that movie. You know. Now,

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Speaker 1: this question kind has two components to it, Like you

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Speaker 1: just said, it has gravity and time in it. And

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Speaker 1: because we know from physics that somehow gravity affects time

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Speaker 1: or is related to time, because in the time can

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Speaker 1: be affected. It's not like some sort of absolute thing.

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Speaker 1: That's right. We do not have like a single clock

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Speaker 1: for the universe. The simplest model of how time works

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Speaker 1: might be imagining that the universe all over the place

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Speaker 1: is in one state. You know, particles are going in

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Speaker 1: some direction or they're in some location, and then things

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Speaker 1: sort of tick forwards and everything takes a step forward

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Speaker 1: in unison and in that picture, the whole universe has

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Speaker 1: like a single clock. But we've learned over the last

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Speaker 1: time of years that that conception of time is not valid.

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Speaker 1: That time flows differently in different parts of the universe,

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Speaker 1: and differently four different observers and moving at different speeds.

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Speaker 1: So time is much weirder, more local, and less universal

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Speaker 1: than we ever imagined. In addition, it's also weirdly bent

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Speaker 1: by heavy objects. Yeah, things that are really heavy, like

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Speaker 1: black holes or even just our planet. They have gravity,

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Speaker 1: and that somehow makes time slowed down. Now, that's a

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Speaker 1: that's a pretty weird concept. Bread. I guess that was

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Speaker 1: in that movie Interstellar. It was exactly in that movie Interstellar.

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Speaker 1: Every time they visited a really heavy planet or came

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Speaker 1: near a black hole. When they left, they found that

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Speaker 1: the rest of the universe had experienced a lot more

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Speaker 1: time than they have. And so I think a lot

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Speaker 1: of people are maybe familiar with this part of relativity,

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Speaker 1: where like, if you're moving past, time slows down. But

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Speaker 1: also it also happens when you're near a heavy object.

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Speaker 1: That's right. These are two completely separate effects with different

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Speaker 1: sources and importantly different mechanisms and different consequences. Yeah, so

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Speaker 1: as usually when we were wondering how many people out

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Speaker 1: there even knew that gravity slowed down time or much less,

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Speaker 1: I have thought about why it slows down time. So

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Speaker 1: Daniel went out there into the internet to ask people

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Speaker 1: why does gravity slow down time? I like the way

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Speaker 1: you say I went out there into the internet. It

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Speaker 1: makes me feel like I got sucked into my computer

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Speaker 1: and went and visited these people like tron like the

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Speaker 1: m eighties movie plotline and you got, you know, salkt

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Speaker 1: into your CRT monitor. Yeah, I'm writing those tron cycles

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Speaker 1: around the Internet, gathering information from our lisitors, dodging calls

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Speaker 1: and tweeting left and right. But if you out there

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Speaker 1: would like me to beat myself into your inbox with

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Speaker 1: crazy questions about the nature of the universe so you

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Speaker 1: can hear yourself speculate about them on the podcast, Please

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Speaker 1: don't be shy. Right to me two questions at Daniel

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Speaker 1: and Jorge dot com. Yeah, and you actually answer every email, right,

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Speaker 1: I do answer every email with every question from everybody.

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Speaker 1: You take the time. It slows me down, but I

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Speaker 1: love it all. Right. Well, here's what people had to say. Well,

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Speaker 1: gravity is basically the same as acceleration, and when you're accelerating,

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Speaker 1: the speed of light stays the same for everybody, and

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Speaker 1: so it must be time that's slowing down. And when

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Speaker 1: we're going at our normal speeds, you don't really notice it. Um.

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Speaker 1: So gravity being equivalent to acceleration causes the same effect.

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Speaker 1: Gravity slows down time because as particles with mass moved

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Speaker 1: through the Higgs field, they're slowed down. The stronger the

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Speaker 1: Higgs field, the gravity is the sole of the quarks

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Speaker 1: and leptons move, causing quantum interactions to take place at

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Speaker 1: a different rate depending on the strength of the field.

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Speaker 1: Scaled up into the macro world, that's what we experienced

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Speaker 1: this time. We would never notice if our particles were

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Speaker 1: moving at a faster slower speed, if everything we observed

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Speaker 1: was experiencing the same Higgs field along with us. I

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Speaker 1: guess that the reason it's because of gravity bench down

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Speaker 1: of pace time and thinks the length of space faith

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Speaker 1: changes in order for the speed of life we're being constant.

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Speaker 1: Was the time of flowing differently. First of all, time

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Speaker 1: is like space dimensions, so the gravity can affect time.

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Speaker 1: But how I'm thinking right now, like the gravity does

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Speaker 1: to also the objects that contracts them. And this is

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Speaker 1: what I'm thinking, That it contracts time. It squeezes it

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Speaker 1: like the space and doing this it is slowing it down.

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Speaker 1: I guess gravity could slow down time because gravity makes

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Speaker 1: those wells and like the space time fabric, and so

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Speaker 1: as that material of the universe gets stretched out, the

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Speaker 1: time would slow down as it gets deeper, sort of

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Speaker 1: like if you're driving over hills versus driving over flat things.

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Speaker 1: I can only imagine it's got something to do with

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Speaker 1: space time. Like gravity isn't just a force, but as

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Speaker 1: Einstein says, it's a warping of space time. And if

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Speaker 1: you've got a ton of gravity staying a black hole,

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Speaker 1: warping space space is not really a thing, but space

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Speaker 1: time is a thing. So you can't affect one without

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Speaker 1: affecting the other, is what I'm guessing. I know time

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Speaker 1: moves slower relatively speaking for someone that travels faster, So

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Speaker 1: maybe gravity slows town time because it also necessarily makes

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Speaker 1: an objectile person move faster. All right, some pretty good

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Speaker 1: answers here. A lot of people sort of knew that

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Speaker 1: time can slow down, and I guess they assume that

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Speaker 1: gravity is someone related to really activity and moving fast

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Speaker 1: and so why not. Yeah, a lot of really interesting

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Speaker 1: and insightful and thoughtful questions here, some confusion about the

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Speaker 1: role of the Higgs field, but also a lot of

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Speaker 1: good concepts about the connections between space and time and

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Speaker 1: how masses have to bend both of them. All right, well,

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Speaker 1: let's get into this idea of time slowing down, and

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Speaker 1: I guess let's recap maybe the one people are most

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Speaker 1: familiar with, maybe, which is the one that when you're

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Speaker 1: moving fast and especially close to the speed of light,

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Speaker 1: time slows down for you. So maybe walk us through that,

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Speaker 1: and then we'll get into the one about gravitation. That's right,

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Speaker 1: So the one you're probably more familiar with. We call

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Speaker 1: velocity time dilation. This is something that happens in special relativity.

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Speaker 1: And to think about this, you should imagine an empty universe,

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Speaker 1: one without really massive objects that are gonna make space

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Speaker 1: curvy and all sorts of weird stuff. In this universe,

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Speaker 1: light travels in straight lines, and spaceships zoom around and

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Speaker 1: all the time. Dilation just comes from the relative velocity

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Speaker 1: of objects. And the most important thing to remember is

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Speaker 1: that movie clocks run slowly, so people often make the

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Speaker 1: mistake of saying, oh, I'm going fast in a spaceship,

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Speaker 1: so my time should slow down, right, Well, it's only

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Speaker 1: moving clocks that slow down. So if you're in a

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Speaker 1: spaceship and you're holding the clock, then the clock is

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Speaker 1: not moving relative to you, so you're not going to

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Speaker 1: see it slow down. So you never experience velocity time

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Speaker 1: dilation because you're never moving a relative to yourself. Somebody

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Speaker 1: else out there on a planet that you're zipping by

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Speaker 1: could see your clock running slowly because your clock is

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Speaker 1: moving for them, and so moving clocks run slowly, meaning

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Speaker 1: that your clock would run slow. You don't experience it,

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Speaker 1: but they see your clock moving slowly. Right, Like, if

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Speaker 1: your time is moving slowly, you don't notice it because

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Speaker 1: you know your brain is also sort of moving slowly

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Speaker 1: in a way, right, So like everything about you is

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Speaker 1: moving slowly as well, and so you don't notice that

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Speaker 1: you're actually moving slowly. But even that suggested some sort

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Speaker 1: of like universal picture of what really happened. And in

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Speaker 1: the universal picture, it makes sense for you to feel

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Speaker 1: like time move normally even though it actually moved slowly.

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Speaker 1: But there is no like what actually happened. Some observers

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Speaker 1: seeing you go by the planet at the speed of light.

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Speaker 1: They see your time as moving slowly. You see your

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Speaker 1: time as moving normally. You can try to unify those

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Speaker 1: into one picture of what actually happened, but there is

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Speaker 1: no what actually happened. There's just what different observers observe,

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Speaker 1: and what you see depends on where you are and

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Speaker 1: how fast things are moving relative to you. For example,

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Speaker 1: if you're on the space ship and you're looking at

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Speaker 1: the clock on Earth, you see Earth moving past you

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Speaker 1: at high speed, and so you see Earth clock running slowly.

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Speaker 1: So Earth sees your clock running slow. You see Earth

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Speaker 1: clock running slow. What actually happened, Well, both of those

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Speaker 1: things happened. Is just what happened depends on where you are.

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Speaker 1: I guess maybe stem me through it. So I'm here

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Speaker 1: on Earth, I'm watching you on a spaceship go by

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Speaker 1: the speed of light, Like, what does it mean for

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Speaker 1: me to see your time slow down? Like? I see

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Speaker 1: your the clock inside of your spaceship take but it's

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Speaker 1: not taking as fast as my clock exactly. So you

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Speaker 1: get a telescope. It's super powerful. So you can look

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Speaker 1: at a clock that's inside my ship and you watch

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Speaker 1: it and you see it's ticks going and you compare

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Speaker 1: it to a clock that's right in your hand, not

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Speaker 1: moving relative to you. And so every time my clock

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Speaker 1: ticks on the spaceship, you see the clock in your

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Speaker 1: lap taking ten times. So time is moving faster for

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Speaker 1: you in your lap. Then you see it moving for

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Speaker 1: me on this ship. And this, of course already takes

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Speaker 1: to an account the fact that it takes light time

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Speaker 1: to get to you to the telescope from the ship.

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Speaker 1: We sort of factor that out already. So what does

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Speaker 1: it mean. So I have a telescope and I'm pointing

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Speaker 1: it at you, but you're zooming by, so I have

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Speaker 1: to kind of track. You have to move my telescope,

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Speaker 1: and so I track you as you're going by, and

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Speaker 1: I'm moving my telescope and I'm measuring your ticks and

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Speaker 1: they're not taking as fast as my clock. That's right.

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Speaker 1: You see my clock as running slowly. So you see

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Speaker 1: me aging slowly, You see me moving slowly. You see

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Speaker 1: me like waving back to you in super slow motion.

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Speaker 1: So you see my clock is running slow relative to

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Speaker 1: your clock. And that's the sort of a consequence of

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Speaker 1: just how the universe is or or to the somehow

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Speaker 1: the limitations of the speed of light. Yeah, it's really interesting.

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Speaker 1: You can start from lots of different places to derive this.

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Speaker 1: You can say like, well, we've seen that nothing can

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Speaker 1: move faster than the speed of light. That's a hard

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Speaker 1: limit on the speed of information. And from that you

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Speaker 1: can derive these things, these time dilation effects, and you

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Speaker 1: can walk yourself through an example. We actually have it

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Speaker 1: worked out in detail in our book We have No Idea,

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Speaker 1: a Guide to the Unknown Universe. And you can think

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Speaker 1: about how a photon clock would tick in a spaceship

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Speaker 1: as it moves up and down, and if it's moving

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Speaker 1: really fast and it has to go like a little

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Speaker 1: bit diagonal for example, And because light can't move faster

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Speaker 1: than the speed of light, when it moves on a diagonal,

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Speaker 1: it takes longer to get from one side of the

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Speaker 1: clock to the other. So it's basically the constancy of

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Speaker 1: the speed of light and the fact that nothing, even

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Speaker 1: light can move faster than the speed of light directly

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Speaker 1: lead to this consequence. The time goes slower for moving

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Speaker 1: clock right. And so there's this sort of famous scenario

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Speaker 1: called the twin paradox for the twin experiment where like

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Speaker 1: you take a pair of twins here on Earth, and

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Speaker 1: you put one of them in a spaceship that goes

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Speaker 1: out into space at the speed of light and then

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Speaker 1: comes back, and supposedly when they come back there are

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Speaker 1: a different age than the one that stayed on Earth.

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Speaker 1: This is a wonderful paradox because it gets to the

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Speaker 1: heart of like what actually happened. Because in the example

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Speaker 1: we're talking about, it feels awfully symmetric, right like I'm

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Speaker 1: looking at you through my telescope and I'm seeing your

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Speaker 1: clock take slowly. But maybe on the ship you're also

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Speaker 1: looking at me on Earth and you see my clock

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Speaker 1: taking slowly. So you want to feel like, well, what

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Speaker 1: actually happens? And the way to bring that to a

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Speaker 1: point is to like bring those two people back together.

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Speaker 1: So if one twin goes off on their spaceship twin

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Speaker 1: on Earth sees the spaceship twin aging slowly, and the

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Speaker 1: spaceship twin sees the Earth twin aging slowly, and so

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Speaker 1: you want to feel like, well, which one is actually younger?

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Speaker 1: And so you turn the spaceship twin around bring it

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Speaker 1: back to Earth, and you ask like, well, which and

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Speaker 1: is younger? And what you discover is that the spaceship

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Speaker 1: twin is younger, and so that sort of breaks this symmetry.

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Speaker 1: And you wonder, like, hold on a second, if this

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Speaker 1: is supposed to be symmetric, if it just depends on

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Speaker 1: relative velocities, why is it that one of them is

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Speaker 1: now younger than the other. So that means it's not

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Speaker 1: just like a perception thing, it's like time actually slowed

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Speaker 1: down for the space twin. In that case, it is

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Speaker 1: because they've broken special relativity. One of the rules of

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Speaker 1: special relativity is no acceleration. You can fly at high

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Speaker 1: velocity and then you can make all these measurements and

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Speaker 1: do these calculations, and things are just as we described.

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Speaker 1: But as soon as you accelerate, then you're out of

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Speaker 1: the bounds of special relativity. It's something you can do.

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Speaker 1: We can you can do it, we can calculate it.

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Speaker 1: But it makes things more complicated, and the simple rules

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Speaker 1: we described earlier of moving clocks run slow get much

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Speaker 1: more tricky. So here, for example, when the spaceship twin

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Speaker 1: turns around to come back to Earth so that he

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Speaker 1: or she can compare her age with her twin, then

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Speaker 1: she's accelerating because changing your direction means accelerating, And what

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Speaker 1: happens when you accelerate is you break the symmetry. Now

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Speaker 1: one of the twins is accelerating, the other one is not,

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Speaker 1: And when you accelerate, weird things happen to time. Specifically,

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Speaker 1: when the twin in the spaceship turns around and accelerates,

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Speaker 1: time jumps forward for the rest of the universe. So

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Speaker 1: time runs a little slower for the accelerating twin jumping

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Speaker 1: forward for the rest of the universe, which is why

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Speaker 1: the twin in the spaceship now is younger when they

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Speaker 1: arrive at Earth than the twin that stayed home. You

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Speaker 1: just kind of accelerated a little too fast there for

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Speaker 1: my brain, I guess. One question is, but isn't acceleration

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Speaker 1: also relative? Like if I'm accelerating away from you, I

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Speaker 1: see you accelerating away from me, So why is an

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Speaker 1: acceleration also like kind of symmetric. And the second question

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Speaker 1: is you're saying it's the acceleration that causes time to

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Speaker 1: slow down, so that's sort of a different scenario. Yeah,

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Speaker 1: these are great questions. Acceleration is actually absolute. Velocity can

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Speaker 1: only be measured relative to other stuff, like if you're

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Speaker 1: an empty universe. You can't measure your velocity because there's

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Speaker 1: nothing to move past. Right, velocity is only defined only

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Speaker 1: has meaning relative to other objects. That's not true for acceleration.

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Speaker 1: Acceleration is something you can measure, even in an empty universe. So,

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Speaker 1: for example, put yourself in a spaceship. You're in an

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Speaker 1: empty universe. If you're moving, your motion has no meaning.

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Speaker 1: There's no experiment you can do inside your spaceship to

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Speaker 1: measure your actual velocity because there's nothing outside to measure

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Speaker 1: relative too. That's not true for acceleration. You can measure

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Speaker 1: inside your spaceship whether or not you're accelerating. For example,

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Speaker 1: you can tell do I feel a force by being

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Speaker 1: pressed by one side of the spaceship. You'll feel those

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Speaker 1: g forces if you're accelerating. So acceleration is different from velocity.

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Speaker 1: You can't have an absolute acceleration, you can measure it.

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Speaker 1: And so that's why the rules are different for acceleration

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Speaker 1: and for velocity. And so then you're saying that the

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Speaker 1: twin who went out into space will actually be younger

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Speaker 1: when they come back, they will actually be younger. Exactly,

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Speaker 1: So when the twin comes back to Earth and is

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Speaker 1: now in the same reference frame moving no velocity relative

430
00:23:05,040 --> 00:23:07,720
Speaker 1: to the other twin. Then you can ask real questions

431
00:23:07,960 --> 00:23:10,520
Speaker 1: about in this reference frame, who is younger and who

432
00:23:10,640 --> 00:23:13,320
Speaker 1: is older. And because the twin that went into space

433
00:23:13,480 --> 00:23:17,160
Speaker 1: also did some acceleration, their time slowed down a lot

434
00:23:17,320 --> 00:23:20,600
Speaker 1: during that acceleration, or equivalently, time for the rest of

435
00:23:20,600 --> 00:23:23,960
Speaker 1: the universe jumped forward during that acceleration. So that breaks

436
00:23:24,000 --> 00:23:27,879
Speaker 1: the symmetry because only one twin accelerated, and so the

437
00:23:27,920 --> 00:23:30,119
Speaker 1: twins stay at home actually is older. And you know

438
00:23:30,200 --> 00:23:32,920
Speaker 1: this isn't just like a thought experiment. There actually are

439
00:23:33,000 --> 00:23:35,719
Speaker 1: a pair of twin astronauts. One of them went and

440
00:23:35,760 --> 00:23:37,320
Speaker 1: spent a lot of time up in space and the

441
00:23:37,400 --> 00:23:41,040
Speaker 1: other one didn't, and they've compared the two. Really all right, well,

442
00:23:41,119 --> 00:23:44,120
Speaker 1: let's get into that real life experiment and then let's

443
00:23:44,119 --> 00:23:47,600
Speaker 1: talk about how gravity changes time. But first let's take

444
00:23:47,640 --> 00:24:02,520
Speaker 1: a quick break. All right, we're asking the question why

445
00:24:02,560 --> 00:24:05,880
Speaker 1: does gravity slow down time? And we were talking first

446
00:24:05,920 --> 00:24:08,239
Speaker 1: about the twin experiment where you send a twin out

447
00:24:08,280 --> 00:24:11,239
Speaker 1: into space, they go really fast, they come back and

448
00:24:11,280 --> 00:24:15,000
Speaker 1: they've aged less. And this age and you're saying is

449
00:24:15,000 --> 00:24:17,359
Speaker 1: actually due to the acceleration, it's not actually due to

450
00:24:17,400 --> 00:24:19,879
Speaker 1: the speed. Right, there are two effects there. There's the

451
00:24:19,960 --> 00:24:22,600
Speaker 1: velocity time dilation, which is the one you're very familiar

452
00:24:22,640 --> 00:24:25,680
Speaker 1: with where moving clocks appear to be slow. But that's

453
00:24:25,720 --> 00:24:28,520
Speaker 1: not a universal phenomenon. It depends on who is doing

454
00:24:28,520 --> 00:24:32,200
Speaker 1: the observing and their relative velocity. Acceleration, however, is different,

455
00:24:32,240 --> 00:24:36,280
Speaker 1: and the acceleration does cause an actual slowing of time,

456
00:24:36,680 --> 00:24:39,960
Speaker 1: which could be measured by everybody because it's not symmetric,

457
00:24:40,040 --> 00:24:44,080
Speaker 1: it's absolute. You can measure somebody's absolute acceleration and that

458
00:24:44,160 --> 00:24:46,800
Speaker 1: makes them different, so it breaks the symmetry. So really,

459
00:24:46,800 --> 00:24:48,919
Speaker 1: when people say going fast slow is down time, we

460
00:24:48,920 --> 00:24:52,399
Speaker 1: really we should be saying accelerating fast causes time to slow.

461
00:24:52,680 --> 00:24:56,000
Speaker 1: And is that something that just somehow changes time or

462
00:24:56,520 --> 00:24:59,320
Speaker 1: is it because you're pushing all of the particles and

463
00:24:59,359 --> 00:25:02,280
Speaker 1: somehow that's blows how they interact, or how how do

464
00:25:02,359 --> 00:25:05,199
Speaker 1: you explain exploration changing time? Well, first of all, it

465
00:25:05,280 --> 00:25:08,000
Speaker 1: is still correct to say that moving fast slows down time.

466
00:25:08,040 --> 00:25:11,280
Speaker 1: It's just that it's slows down time only for observers, right,

467
00:25:11,600 --> 00:25:14,800
Speaker 1: observers moving fast relative to those clocks. It's still true,

468
00:25:15,000 --> 00:25:17,760
Speaker 1: it still happens. It's it's not like just a perception issue.

469
00:25:17,800 --> 00:25:20,920
Speaker 1: It's a true thing about the universe. Acceleration slows down

470
00:25:20,920 --> 00:25:23,440
Speaker 1: time in a different way. It's a different mechanism. It's

471
00:25:23,480 --> 00:25:25,199
Speaker 1: much harder to understand in terms of it means like

472
00:25:25,359 --> 00:25:27,879
Speaker 1: ticks on the photon clock. But you can see it

473
00:25:27,880 --> 00:25:30,560
Speaker 1: also comes as a consequence of the speed of light.

474
00:25:30,720 --> 00:25:33,560
Speaker 1: All right, well then, so that's acceleration and time dilation

475
00:25:33,680 --> 00:25:37,159
Speaker 1: because of exceleraation and because of going close to the

476
00:25:37,160 --> 00:25:38,920
Speaker 1: speed of light. But the one we're talking about today

477
00:25:39,000 --> 00:25:42,480
Speaker 1: is the one due to gravity. So whenever you're next

478
00:25:42,480 --> 00:25:47,200
Speaker 1: to something that's really heavy or massive, time also slows down.

479
00:25:47,880 --> 00:25:50,560
Speaker 1: But does it slow down in the same way that

480
00:25:50,640 --> 00:25:53,240
Speaker 1: acceleration slows time down, or does it slow down in

481
00:25:53,240 --> 00:25:56,040
Speaker 1: the same way that going at a constant speed slows time?

482
00:25:56,080 --> 00:25:57,400
Speaker 1: Do you know what I mean? Like is it observer

483
00:25:57,480 --> 00:26:00,800
Speaker 1: base or is it actually like time slowing down? Great question.

484
00:26:01,280 --> 00:26:04,600
Speaker 1: And so gravity slows down time where the curvature of

485
00:26:04,720 --> 00:26:08,199
Speaker 1: space slows down time, and this effect on time is

486
00:26:08,240 --> 00:26:12,360
Speaker 1: the same as acceleration slowing down time. And in fact,

487
00:26:12,440 --> 00:26:16,080
Speaker 1: it's sort of a deep idea here because in general relativity,

488
00:26:16,359 --> 00:26:19,959
Speaker 1: one of the whole inspirational ideas of general relativity is

489
00:26:20,000 --> 00:26:23,360
Speaker 1: that gravity is equivalent to acceleration. You know, the experiment

490
00:26:23,400 --> 00:26:25,280
Speaker 1: we talked about a minute ago, like, if you were

491
00:26:25,440 --> 00:26:28,720
Speaker 1: in space, could you tell if your spaceship was accelerating,

492
00:26:28,880 --> 00:26:30,840
Speaker 1: You could, and in fact it would feel like you

493
00:26:30,880 --> 00:26:34,400
Speaker 1: were being pressed against one wall of the ship, or equivalently,

494
00:26:34,720 --> 00:26:37,320
Speaker 1: it would feel like you were standing on a planet

495
00:26:37,359 --> 00:26:40,879
Speaker 1: with gravity. Right, you can in fact make artificial gravity

496
00:26:40,920 --> 00:26:44,240
Speaker 1: on a spaceship by providing acceleration, either by spinning or

497
00:26:44,280 --> 00:26:47,360
Speaker 1: by zooming off in one direction. So the whole idea

498
00:26:47,440 --> 00:26:51,080
Speaker 1: that gave Einstein the inspiration for general relativity was this

499
00:26:51,119 --> 00:26:53,800
Speaker 1: one is called the equivalence principle that says that there's

500
00:26:53,840 --> 00:26:58,639
Speaker 1: no difference between gravity and acceleration. And so we just

501
00:26:58,680 --> 00:27:02,639
Speaker 1: went through the details of how acceleration can cause time

502
00:27:02,720 --> 00:27:05,400
Speaker 1: to move slowly, and this is exactly the same effect.

503
00:27:05,560 --> 00:27:09,760
Speaker 1: Gravity also makes time move slowly. The curvature of space

504
00:27:09,800 --> 00:27:13,520
Speaker 1: around you makes time move more slowly. It's exactly the

505
00:27:13,520 --> 00:27:16,119
Speaker 1: same effect. And so it's an absolute effect, not a

506
00:27:16,200 --> 00:27:19,480
Speaker 1: relative one like for velocity. So you're saying it's really

507
00:27:19,520 --> 00:27:22,240
Speaker 1: sort of acceleration that causes time to slow down, and

508
00:27:22,359 --> 00:27:25,359
Speaker 1: gravity is sort of like an acceleration or is it

509
00:27:25,400 --> 00:27:27,040
Speaker 1: the other way around? But I guess you can have

510
00:27:27,040 --> 00:27:30,200
Speaker 1: acceleration without gravity, So it's more like gravity is kind

511
00:27:30,200 --> 00:27:32,760
Speaker 1: of like an acceleration. Yeah, gravity is essentially like a

512
00:27:32,800 --> 00:27:37,399
Speaker 1: geometrical interpretation of acceleration. Or you know, said another way,

513
00:27:37,680 --> 00:27:40,439
Speaker 1: what happens when you have mass in space, Well, it

514
00:27:40,600 --> 00:27:44,440
Speaker 1: changes the curvature of that space, and so what happens

515
00:27:44,440 --> 00:27:47,120
Speaker 1: then is that things move differently and they can appear,

516
00:27:47,160 --> 00:27:50,480
Speaker 1: for example, to be accelerating. If you aren't aware of

517
00:27:50,520 --> 00:27:53,159
Speaker 1: the curvature of space, then it seems like there's a

518
00:27:53,200 --> 00:27:57,119
Speaker 1: force there which provides an acceleration towards those masses. And

519
00:27:57,160 --> 00:28:00,480
Speaker 1: so that's really what gravity is. Gravity is the bending

520
00:28:00,560 --> 00:28:03,560
Speaker 1: of space in a way that appears to provide acceleration.

521
00:28:03,920 --> 00:28:07,439
Speaker 1: So gravity and acceleration really are exactly the same phenomenon.

522
00:28:07,520 --> 00:28:11,360
Speaker 1: Either acceleration in empty flat space gives exactly the same

523
00:28:11,400 --> 00:28:14,920
Speaker 1: effects as curving of space itself. You remember, we did

524
00:28:14,960 --> 00:28:19,280
Speaker 1: recently a fun episode about how if you're accelerating there

525
00:28:19,320 --> 00:28:22,560
Speaker 1: are times that photons cannot catch you. You have essentially

526
00:28:22,640 --> 00:28:26,919
Speaker 1: an event horizon if you're accelerating constantly, And the explanation

527
00:28:26,920 --> 00:28:29,720
Speaker 1: there was the same as here is that accelerating constantly

528
00:28:30,000 --> 00:28:33,159
Speaker 1: is sort of the same as curving space. And we

529
00:28:33,200 --> 00:28:35,640
Speaker 1: know that if you curve space, weird things happen, like

530
00:28:35,840 --> 00:28:38,719
Speaker 1: you can be inside a black hole and photons cannot escape.

531
00:28:39,080 --> 00:28:41,640
Speaker 1: And so the core idea here is to understand that

532
00:28:41,720 --> 00:28:45,280
Speaker 1: accelerating is really the same thing as gravity, And so

533
00:28:45,440 --> 00:28:48,360
Speaker 1: if you think of gravity is causing time dilation, it's

534
00:28:48,400 --> 00:28:51,680
Speaker 1: really the concept of acceleration causing time dilation the sort

535
00:28:51,720 --> 00:28:54,320
Speaker 1: of mentally equivalent. There are a lot of leaps here,

536
00:28:54,360 --> 00:28:56,000
Speaker 1: I feel like, and it's kind of hard to keep

537
00:28:56,000 --> 00:28:58,960
Speaker 1: track of because I feel like you're saying gravity is

538
00:28:59,000 --> 00:29:03,240
Speaker 1: acceleration and gravity is also the curvature of space. Does

539
00:29:03,280 --> 00:29:06,160
Speaker 1: that mean that all acceleration is also the curvature of space?

540
00:29:06,440 --> 00:29:10,719
Speaker 1: Or can you have acceloration in not bend space, or like,

541
00:29:10,880 --> 00:29:14,520
Speaker 1: can you think of all acceleration even by like electromagnetic forces,

542
00:29:14,600 --> 00:29:16,840
Speaker 1: as some sort of curvature of space. Yeah, that's a

543
00:29:16,920 --> 00:29:19,560
Speaker 1: deep question, and there are people out there trying to

544
00:29:19,600 --> 00:29:23,320
Speaker 1: interpret all acceleration in terms of the curvature space, or

545
00:29:23,400 --> 00:29:26,080
Speaker 1: you know, like all forces as being the product of

546
00:29:26,080 --> 00:29:29,440
Speaker 1: the curvature space. But that's not necessary. You can think

547
00:29:29,480 --> 00:29:32,920
Speaker 1: about acceleration in flat space, you know, just like put

548
00:29:32,920 --> 00:29:35,960
Speaker 1: on a rocketship, accelerate your spaceship. Now you're going fast.

549
00:29:36,280 --> 00:29:39,000
Speaker 1: But the effects of that on your time and the

550
00:29:39,000 --> 00:29:42,280
Speaker 1: way you pursue you the universe are equivalent to if

551
00:29:42,360 --> 00:29:45,280
Speaker 1: space was curved around you. So you can think of

552
00:29:45,320 --> 00:29:48,320
Speaker 1: acceleration separately from the curvature space and from gravity, but

553
00:29:48,400 --> 00:29:50,960
Speaker 1: has exactly the same effect, because that's really kind of

554
00:29:50,960 --> 00:29:53,600
Speaker 1: what gravity is, so meaning I feel like then that

555
00:29:53,680 --> 00:29:56,800
Speaker 1: you're saying that that it's not really gravity that slowing

556
00:29:56,840 --> 00:30:00,600
Speaker 1: down time. It's really the acceleration caused by gravity, or

557
00:30:00,600 --> 00:30:02,800
Speaker 1: the bending of space caused by gravity, which is the

558
00:30:02,840 --> 00:30:05,560
Speaker 1: same as exceleration. Yeah, there's lots of different ways to

559
00:30:05,560 --> 00:30:08,360
Speaker 1: think about it. You can think of acceleration caused by

560
00:30:08,400 --> 00:30:12,280
Speaker 1: gravity is really just like motion through curved space. And

561
00:30:12,320 --> 00:30:14,840
Speaker 1: one of the other impacts of curved space is that

562
00:30:14,920 --> 00:30:18,640
Speaker 1: time also slows down. All right, well, then maybe let's

563
00:30:18,640 --> 00:30:21,720
Speaker 1: try it. Let's see why does acceleration slow down time?

564
00:30:22,360 --> 00:30:24,480
Speaker 1: Because that seems to be the bigger problem, right, that

565
00:30:24,520 --> 00:30:26,920
Speaker 1: seems to be the bigger question. Yeah, so I guess

566
00:30:26,960 --> 00:30:29,840
Speaker 1: you can say that gravity slows down time because it's

567
00:30:29,840 --> 00:30:33,960
Speaker 1: equivalent to acceleration slowing down time. Why does acceleration slow

568
00:30:34,000 --> 00:30:36,960
Speaker 1: down time? That gets back to the speed of light

569
00:30:37,040 --> 00:30:39,640
Speaker 1: as the limiting piece of information. You can derive this

570
00:30:39,680 --> 00:30:42,400
Speaker 1: in a flat universe using the twins as an example.

571
00:30:42,680 --> 00:30:45,520
Speaker 1: It's a little bit more complicated mathematically than like normal

572
00:30:45,600 --> 00:30:48,600
Speaker 1: special relativity, where you can do these observing frames with

573
00:30:48,680 --> 00:30:52,480
Speaker 1: Lorentz transformations. It gets a little hairy and mathematical, but

574
00:30:52,560 --> 00:30:55,959
Speaker 1: the core concept that it comes from is this maximum

575
00:30:56,000 --> 00:30:59,920
Speaker 1: speed of light. Everything comes out of that both time

576
00:31:00,040 --> 00:31:03,720
Speaker 1: dilation from velocity and also time dilation from acceleration, which

577
00:31:03,720 --> 00:31:07,040
Speaker 1: really is equivalent to time dilation from gravity. So I

578
00:31:07,080 --> 00:31:09,760
Speaker 1: guess if I'm in a spaceship and I'm accelerating the

579
00:31:09,840 --> 00:31:12,800
Speaker 1: limitations of the speed of light, which does that mean that?

580
00:31:13,040 --> 00:31:15,400
Speaker 1: Are you sort of saying that it somehow limits how

581
00:31:15,560 --> 00:31:18,600
Speaker 1: the things can evolve inside of that spaceship, you know,

582
00:31:18,720 --> 00:31:22,680
Speaker 1: move from you know, information between molecules and things like that,

583
00:31:22,760 --> 00:31:25,560
Speaker 1: So things sort of evolve slower or they have a

584
00:31:25,560 --> 00:31:28,120
Speaker 1: limit to how fast they can evolve. Yeah, I would

585
00:31:28,120 --> 00:31:31,160
Speaker 1: say a little bit differently. I would say that requiring

586
00:31:31,360 --> 00:31:33,840
Speaker 1: that the speed of light is constant and that everybody

587
00:31:33,840 --> 00:31:36,120
Speaker 1: observes the speed of light always to be. The speed

588
00:31:36,160 --> 00:31:39,880
Speaker 1: of light restricts the kinds of universes that we can have.

589
00:31:40,280 --> 00:31:42,960
Speaker 1: It puts a lot of restrictions on the waste space

590
00:31:43,000 --> 00:31:46,200
Speaker 1: and time have to work in that universe. And these

591
00:31:46,280 --> 00:31:49,280
Speaker 1: effects that we're talking about, the slowing down of time

592
00:31:49,560 --> 00:31:53,600
Speaker 1: by velocity and by acceleration, are consequences of the structure

593
00:31:53,720 --> 00:31:56,160
Speaker 1: of that space and time the sort of come out

594
00:31:56,200 --> 00:31:58,120
Speaker 1: of that all, right, So you're saying it's just the

595
00:31:58,120 --> 00:32:01,840
Speaker 1: way it is saying when things accelerate, there's a limit

596
00:32:01,880 --> 00:32:04,280
Speaker 1: in the speed of light, and so that makes time

597
00:32:04,320 --> 00:32:07,520
Speaker 1: sort of slow down, makes everything slow down. And I

598
00:32:07,560 --> 00:32:10,640
Speaker 1: think it's super cool because it's not symmetric. You know,

599
00:32:10,760 --> 00:32:13,800
Speaker 1: like two people can agree on who is accelerating more,

600
00:32:14,240 --> 00:32:16,680
Speaker 1: and so that means that they can agree on whose

601
00:32:16,720 --> 00:32:19,520
Speaker 1: time is moving more slowly, or you know, said another

602
00:32:19,560 --> 00:32:22,280
Speaker 1: way in terms of gravity, like you and I can

603
00:32:22,320 --> 00:32:25,240
Speaker 1: agree that if you're near the black hole, then you're

604
00:32:25,240 --> 00:32:27,480
Speaker 1: in a part of space that's curved more than my

605
00:32:27,600 --> 00:32:30,280
Speaker 1: part of space, and so we can agree that your

606
00:32:30,360 --> 00:32:33,000
Speaker 1: time should be moving more slowly. That's not true for

607
00:32:33,040 --> 00:32:35,840
Speaker 1: the spaceships, right, If we're in two spaceships passing each other,

608
00:32:36,000 --> 00:32:38,600
Speaker 1: it feels symmetric because it is symmetric. I say you're

609
00:32:38,600 --> 00:32:41,960
Speaker 1: moving past me, You say I'm moving past you. Everybody's right.

610
00:32:42,280 --> 00:32:44,240
Speaker 1: In the case of the black hole, we can agree

611
00:32:44,240 --> 00:32:47,080
Speaker 1: it's not symmetric, So we should agree that your time

612
00:32:47,120 --> 00:32:49,800
Speaker 1: is moving more slowly. So then a coloration causes time

613
00:32:49,800 --> 00:32:51,880
Speaker 1: to slow down. And definitely, when you're near a black hole,

614
00:32:52,160 --> 00:32:55,880
Speaker 1: you are being accelerated, probably a lot, because black holes

615
00:32:55,960 --> 00:32:59,280
Speaker 1: are very massive. They're pulling you in. And so if

616
00:32:59,280 --> 00:33:01,600
Speaker 1: I'm near a black hole, then I'm going to be

617
00:33:01,640 --> 00:33:04,640
Speaker 1: moving slower through time than you, who is out way

618
00:33:04,680 --> 00:33:08,360
Speaker 1: far from the black hole exactly. And so another cool

619
00:33:08,400 --> 00:33:11,200
Speaker 1: thing is that I see your time moving slowly. It

620
00:33:11,240 --> 00:33:14,880
Speaker 1: means that you see my time moving more quickly. Right,

621
00:33:14,920 --> 00:33:17,720
Speaker 1: This is the real difference with velocity time dilation and

622
00:33:17,840 --> 00:33:20,280
Speaker 1: velocity time delation. We both see each other's time moving

623
00:33:20,280 --> 00:33:22,720
Speaker 1: more slowly. Here, if you're near a black hole and

624
00:33:22,720 --> 00:33:25,000
Speaker 1: you're looking out into the universe, you see the rest

625
00:33:25,040 --> 00:33:27,920
Speaker 1: of the universe running forward in time very quickly. And

626
00:33:27,920 --> 00:33:29,800
Speaker 1: as you get closer and closer to the black hole

627
00:33:29,840 --> 00:33:32,600
Speaker 1: and more and more curvature, you see the universe's clock

628
00:33:32,720 --> 00:33:35,040
Speaker 1: speeding up into the future. So then like if I'm

629
00:33:35,080 --> 00:33:38,080
Speaker 1: falling into a black hole, like all the stars will

630
00:33:38,080 --> 00:33:40,760
Speaker 1: suddenly start speeding up around me, like I'll see the

631
00:33:40,840 --> 00:33:43,800
Speaker 1: universe kind of and fast forward exactly. And some people imagine, well,

632
00:33:43,840 --> 00:33:45,840
Speaker 1: does that mean that you'll see like the end of

633
00:33:45,920 --> 00:33:48,440
Speaker 1: the universe, the end of time. You'll know, like the

634
00:33:48,480 --> 00:33:51,040
Speaker 1: final fate of the universe just as you fall into

635
00:33:51,040 --> 00:33:53,920
Speaker 1: the black hole. Well that would be super cool, but unfortunately,

636
00:33:53,960 --> 00:33:56,959
Speaker 1: it takes a finite amount of time from your perspective

637
00:33:57,160 --> 00:33:59,120
Speaker 1: to fall into a black hole, so there isn't time

638
00:33:59,160 --> 00:34:02,120
Speaker 1: for all that information from the future universe to get

639
00:34:02,160 --> 00:34:04,960
Speaker 1: to you. So you see the fast forward universe for

640
00:34:05,000 --> 00:34:07,040
Speaker 1: a while, but you don't see like all the way

641
00:34:07,120 --> 00:34:09,680
Speaker 1: into the infinite future. Well, we talked about this last time,

642
00:34:09,719 --> 00:34:11,560
Speaker 1: Like when you actually get to the surface of the

643
00:34:11,600 --> 00:34:16,200
Speaker 1: black hole, then time actually stands still, right, Like it

644
00:34:16,280 --> 00:34:18,400
Speaker 1: slows down more the closer you get to the black hole,

645
00:34:18,920 --> 00:34:20,720
Speaker 1: and then it sort of stands still at the surface.

646
00:34:20,840 --> 00:34:23,759
Speaker 1: It sort of does, but that's only for somebody far away.

647
00:34:24,080 --> 00:34:27,200
Speaker 1: They see your time moving slowly and they see you

648
00:34:27,239 --> 00:34:30,880
Speaker 1: sort of smeared across the event horizon. But for you,

649
00:34:30,880 --> 00:34:33,720
Speaker 1: you actually fall into the black hole, you don't notice

650
00:34:33,760 --> 00:34:36,440
Speaker 1: anything different changing, right, you notice the rest of the

651
00:34:36,480 --> 00:34:39,439
Speaker 1: universe's clock speeding up. But from your perspective, you fall

652
00:34:39,480 --> 00:34:41,719
Speaker 1: into the black hole, you pass the event horizon, you

653
00:34:41,800 --> 00:34:45,120
Speaker 1: get sucked into the singularity, so your time is definitely

654
00:34:45,200 --> 00:34:47,960
Speaker 1: finite from your perspective. And this is not something that

655
00:34:48,000 --> 00:34:50,880
Speaker 1: we understand very well. There's all sorts of weird paradoxes

656
00:34:50,880 --> 00:34:53,319
Speaker 1: and contradictions here about how one person sees you not

657
00:34:53,400 --> 00:34:55,320
Speaker 1: falling into the black hole to the end of time,

658
00:34:55,760 --> 00:34:58,720
Speaker 1: and you see yourself actually falling in. It's not something

659
00:34:58,719 --> 00:35:00,600
Speaker 1: that we know how to reckon. SI. I think what

660
00:35:00,640 --> 00:35:03,000
Speaker 1: you're saying is that the person falling in, you're saying

661
00:35:03,040 --> 00:35:05,560
Speaker 1: they'll see themselves falling through, But we don't actually know

662
00:35:05,600 --> 00:35:08,280
Speaker 1: if that's true, right, Like they might just actually freeze

663
00:35:08,280 --> 00:35:10,480
Speaker 1: at the edge, which just don't know. Yeah, we don't

664
00:35:10,480 --> 00:35:12,520
Speaker 1: know it is true because nobody's done it and come

665
00:35:12,560 --> 00:35:15,319
Speaker 1: to report back. It's possible they actually just freeze the

666
00:35:15,480 --> 00:35:17,920
Speaker 1: edge and they think that they're inside, but it's actually

667
00:35:17,920 --> 00:35:20,319
Speaker 1: that the inside of a black hole is a hologram

668
00:35:20,440 --> 00:35:23,160
Speaker 1: projected from the surface of the black hole. We just

669
00:35:23,280 --> 00:35:25,919
Speaker 1: don't really know what's going on inside a black hole.

670
00:35:26,160 --> 00:35:29,360
Speaker 1: And so this effect of gravity on time doesn't just

671
00:35:29,440 --> 00:35:31,839
Speaker 1: happen in black holes. I mean, black hole is sort

672
00:35:31,880 --> 00:35:34,759
Speaker 1: of the extreme example, but it actually happens like every

673
00:35:34,840 --> 00:35:37,719
Speaker 1: day and everywhere, like here on Earth, the Earth is

674
00:35:37,760 --> 00:35:40,759
Speaker 1: slowing down time and even like I'm slowing down time

675
00:35:41,200 --> 00:35:44,040
Speaker 1: for the things around me, right, yeah, absolutely, everywhere there

676
00:35:44,120 --> 00:35:48,480
Speaker 1: is curvature, time is slowed down and the Earth curved space, right,

677
00:35:48,520 --> 00:35:50,719
Speaker 1: because the Earth has a lot of mass. That's why,

678
00:35:50,760 --> 00:35:52,960
Speaker 1: for example, you don't fall off the Earth. You're feeling

679
00:35:53,040 --> 00:35:55,920
Speaker 1: it's gravity. So anywhere you're in a situation where you're

680
00:35:55,920 --> 00:35:59,400
Speaker 1: feeling gravity, you're also having your time affected. And because

681
00:35:59,440 --> 00:36:02,359
Speaker 1: gravity is stronger as you get closer to the Earth

682
00:36:02,440 --> 00:36:04,840
Speaker 1: and weaker as you move away from it, that means

683
00:36:04,880 --> 00:36:08,160
Speaker 1: that the clocks are variable. Time flows in a variable

684
00:36:08,239 --> 00:36:10,840
Speaker 1: way as a function of the distance from the center

685
00:36:10,840 --> 00:36:13,200
Speaker 1: of the Earth. And this is something you can measure,

686
00:36:13,320 --> 00:36:17,520
Speaker 1: like over your life, your feet will age one second

687
00:36:17,600 --> 00:36:20,759
Speaker 1: more than your head, only if you spent a lot

688
00:36:20,760 --> 00:36:23,799
Speaker 1: of time standing up Daniel, which cartoon is don't do

689
00:36:23,840 --> 00:36:25,879
Speaker 1: a lot of So I guess our feet are still young.

690
00:36:26,080 --> 00:36:28,399
Speaker 1: We are still light on our feet exactly. That's why

691
00:36:28,440 --> 00:36:29,960
Speaker 1: you lay down all the time, just to keep your

692
00:36:30,000 --> 00:36:32,839
Speaker 1: body like in sync, just to keep my feet young.

693
00:36:33,560 --> 00:36:36,240
Speaker 1: All right, well, let's get into what this all means.

694
00:36:36,640 --> 00:36:39,640
Speaker 1: Does that mean that we're all moving slower through time

695
00:36:39,640 --> 00:36:42,640
Speaker 1: than we should? And whether does that mean that also

696
00:36:42,640 --> 00:36:46,400
Speaker 1: there's no universal clock actually to measure time in the universe,

697
00:36:46,920 --> 00:36:49,000
Speaker 1: So let's get into that. But first let's take another

698
00:36:49,160 --> 00:37:04,399
Speaker 1: quick break. All right, Daniel, my favorite question and all

699
00:37:04,440 --> 00:37:08,840
Speaker 1: these topics, what does it all mean? Man? So anything

700
00:37:08,880 --> 00:37:12,880
Speaker 1: with gravity bends space around it, which causes acceleration, and

701
00:37:12,920 --> 00:37:16,600
Speaker 1: accelerating things slowed down in time. So things are always

702
00:37:16,640 --> 00:37:19,719
Speaker 1: slowing down in time everywhere all the time. Yeah, everywhere

703
00:37:19,760 --> 00:37:23,560
Speaker 1: there's a gravitational field, clocks are being slowed. So if

704
00:37:23,560 --> 00:37:26,040
Speaker 1: you're in a gravitational field, then your sense of now

705
00:37:26,920 --> 00:37:30,239
Speaker 1: is moving forward differently than other people who are like

706
00:37:30,360 --> 00:37:32,920
Speaker 1: out in deep space. And so if you spend a

707
00:37:32,920 --> 00:37:35,879
Speaker 1: lot of time near and gravitational objects, then you are

708
00:37:36,080 --> 00:37:38,839
Speaker 1: younger than you otherwise would be. Right, But it's not

709
00:37:38,880 --> 00:37:40,719
Speaker 1: just gravity too, right, It's like if I get in

710
00:37:40,760 --> 00:37:43,080
Speaker 1: my car and I accelerate up to the freeway, I

711
00:37:43,239 --> 00:37:47,480
Speaker 1: somehow slowed down time for myself. Yeah, gravity and acceleration.

712
00:37:47,520 --> 00:37:50,880
Speaker 1: They're equivalent, and so both of them will slow down time.

713
00:37:51,120 --> 00:37:54,360
Speaker 1: Every time you accelerate, the universe sort of leaps forward

714
00:37:54,360 --> 00:37:57,520
Speaker 1: a little bit relative to you. If you accelerated a

715
00:37:57,520 --> 00:37:59,920
Speaker 1: lot for a long time, you would notice clocks around

716
00:38:00,040 --> 00:38:03,359
Speaker 1: you seeming to move forward faster than one second per

717
00:38:03,400 --> 00:38:05,399
Speaker 1: second on your clock. And so I guess that means

718
00:38:05,440 --> 00:38:08,960
Speaker 1: first of all, that there's no real age to the universe.

719
00:38:09,080 --> 00:38:11,360
Speaker 1: Is that really true? That Does that mean that you

720
00:38:11,360 --> 00:38:15,160
Speaker 1: know there's no like absolute time? Yeah, there's no absolute time,

721
00:38:15,160 --> 00:38:17,279
Speaker 1: which is really frustrating if you'd like to have a

722
00:38:17,320 --> 00:38:20,320
Speaker 1: sense that you know, there's truth, that there's something really

723
00:38:20,360 --> 00:38:23,719
Speaker 1: going on out there outside of our skulls. It's frustrating

724
00:38:23,760 --> 00:38:26,680
Speaker 1: to imagine that. Like, different people can tell different stories

725
00:38:26,800 --> 00:38:29,239
Speaker 1: and they can both be correct. But there's an even

726
00:38:29,239 --> 00:38:32,120
Speaker 1: deeper problem if you try to extrapolate back to time

727
00:38:32,160 --> 00:38:35,040
Speaker 1: equal zero. You know, we say this thing the universe

728
00:38:35,200 --> 00:38:38,080
Speaker 1: is thirteen point eight billion years old. Well, according to

729
00:38:38,160 --> 00:38:40,920
Speaker 1: what clock, right, is that clock been moving on a spaceship?

730
00:38:41,000 --> 00:38:42,759
Speaker 1: Has that clock spent a lot of time near a

731
00:38:42,800 --> 00:38:44,880
Speaker 1: black hole? Because if so, it's going to have a

732
00:38:44,880 --> 00:38:47,720
Speaker 1: different answer. And so, because different parts of the universe

733
00:38:47,760 --> 00:38:50,879
Speaker 1: have different curvature, right like near black holes or near

734
00:38:50,960 --> 00:38:53,719
Speaker 1: Sun's or whatever. Then different parts of the universe have

735
00:38:53,960 --> 00:38:57,920
Speaker 1: aged differently since it's beginning. So the universe does not

736
00:38:58,080 --> 00:39:00,839
Speaker 1: have one single age. Just like your feet and your

737
00:39:00,880 --> 00:39:04,279
Speaker 1: head are not the same age, assuming you haven't spent

738
00:39:04,320 --> 00:39:06,480
Speaker 1: your whole life in bed, the parts of the universe

739
00:39:06,560 --> 00:39:09,160
Speaker 1: have different ages. I do a lot of handstands, so

740
00:39:09,520 --> 00:39:11,680
Speaker 1: I'm trying not to go bald, so I'm keeping my head.

741
00:39:11,760 --> 00:39:13,520
Speaker 1: I think we all need a video of you doing

742
00:39:13,520 --> 00:39:18,040
Speaker 1: a handstand. Let's see that. That's good. But I guess

743
00:39:18,040 --> 00:39:21,480
Speaker 1: that confuses me because you told me earlier that acceleration

744
00:39:21,640 --> 00:39:26,240
Speaker 1: is absolute, so I can measure exceloration absolutely, and time

745
00:39:26,520 --> 00:39:30,480
Speaker 1: is actually bent by exploration. So couldn't I, I don't know,

746
00:39:30,600 --> 00:39:33,400
Speaker 1: find a spot in the universe that's never been accelerated

747
00:39:33,920 --> 00:39:37,759
Speaker 1: and say that, like, that's the absolute age of the universe. Well,

748
00:39:37,800 --> 00:39:39,880
Speaker 1: that's the age of that part of the universe, and

749
00:39:39,920 --> 00:39:42,560
Speaker 1: that would be the oldest part of the universe. That

750
00:39:42,640 --> 00:39:45,759
Speaker 1: part would have experienced the most time. But you know,

751
00:39:45,800 --> 00:39:47,759
Speaker 1: if you had put a clock somewhere else in the

752
00:39:47,880 --> 00:39:51,040
Speaker 1: universe and let it run since the beginning, it would

753
00:39:51,040 --> 00:39:53,440
Speaker 1: have a different number. So like different parts of the

754
00:39:53,520 --> 00:39:57,120
Speaker 1: universe have different ages, and you might reasonably say, well,

755
00:39:57,280 --> 00:39:59,200
Speaker 1: the oldest part of the universe, I'm gonna use that

756
00:39:59,400 --> 00:40:02,000
Speaker 1: as the a age of the universe. Yeah, nobody cares

757
00:40:02,000 --> 00:40:07,040
Speaker 1: how young my feet are. I care, I care, you care.

758
00:40:07,239 --> 00:40:08,920
Speaker 1: It sounded a lot like I care though, Right, that

759
00:40:08,960 --> 00:40:12,560
Speaker 1: sounded sincere didn't it. But yeah, so there's sort of

760
00:40:12,560 --> 00:40:14,799
Speaker 1: an age limit to the universe, right, Like you're you're

761
00:40:14,880 --> 00:40:17,400
Speaker 1: saying that there is an absolute age of the universe

762
00:40:17,640 --> 00:40:20,239
Speaker 1: by which we can measure all other ages. Yeah, there's

763
00:40:20,280 --> 00:40:23,480
Speaker 1: a maximum age to the universe, right, there is a

764
00:40:23,760 --> 00:40:26,120
Speaker 1: number beyond which no part of the universe could have

765
00:40:26,160 --> 00:40:29,399
Speaker 1: experienced more time than that if you wanted to find

766
00:40:29,480 --> 00:40:32,120
Speaker 1: that as the age of the whole universe. I guess

767
00:40:32,160 --> 00:40:34,160
Speaker 1: that makes sense, But I think more conceptually it makes

768
00:40:34,160 --> 00:40:36,680
Speaker 1: sense to imagine, like how many clock ticks have there

769
00:40:36,719 --> 00:40:39,160
Speaker 1: been in a given part of the universe, And that's

770
00:40:39,160 --> 00:40:42,239
Speaker 1: not equal all over the universe. It depends on how

771
00:40:42,320 --> 00:40:45,120
Speaker 1: much gravity there is nearby, right, Because I guess even

772
00:40:45,160 --> 00:40:48,399
Speaker 1: our solar system is being accelerated around the Milky Way,

773
00:40:48,480 --> 00:40:50,759
Speaker 1: so therefore our time is sort of being slowed down

774
00:40:51,040 --> 00:40:53,920
Speaker 1: in that way too. Yeah, the curvature of the center

775
00:40:54,080 --> 00:40:56,879
Speaker 1: of the Milky Way and that supermassive black hole does

776
00:40:56,920 --> 00:40:59,320
Speaker 1: affect the motion of the Sun and the curvature nearby,

777
00:40:59,400 --> 00:41:01,880
Speaker 1: which slows down our time. And I guess you were

778
00:41:01,920 --> 00:41:04,200
Speaker 1: trying to tell me earlier that there is sort of

779
00:41:04,200 --> 00:41:10,040
Speaker 1: a philosophical question here, which is like, does acceloration change

780
00:41:10,120 --> 00:41:15,840
Speaker 1: time or does time change acceleration. Yeah, it's familiar to

781
00:41:15,880 --> 00:41:20,520
Speaker 1: think about general relativity is saying that mass causes space

782
00:41:20,719 --> 00:41:24,360
Speaker 1: to bend, and then the curvature of space tells masses

783
00:41:24,360 --> 00:41:27,680
Speaker 1: how to move. Right, that you get an appearance of acceleration,

784
00:41:28,280 --> 00:41:31,399
Speaker 1: this effective force of gravity because space itself is bent.

785
00:41:31,719 --> 00:41:35,040
Speaker 1: There's a missing component there, right, which is that time

786
00:41:35,160 --> 00:41:38,200
Speaker 1: is also curved by mass. So you have mass somewhere,

787
00:41:38,360 --> 00:41:41,319
Speaker 1: it doesn't just curve space, It also curves time, which

788
00:41:41,320 --> 00:41:43,640
Speaker 1: is what we've been talking about today, And the curving

789
00:41:43,680 --> 00:41:47,520
Speaker 1: of time also contributes to this force of gravity. So

790
00:41:47,560 --> 00:41:50,440
Speaker 1: gravity is an apparent force that comes not just from

791
00:41:50,480 --> 00:41:53,560
Speaker 1: the bending of space but also from the bending of time.

792
00:41:53,600 --> 00:41:56,279
Speaker 1: The two work together because spacetime really is sort of

793
00:41:56,560 --> 00:42:00,880
Speaker 1: one thing to create this effect of gravity. You're saying time.

794
00:42:01,000 --> 00:42:03,520
Speaker 1: You can also bend time, just like you can bend space,

795
00:42:04,360 --> 00:42:08,200
Speaker 1: and somehow that's where gravity comes from. Yeah, exactly. It's

796
00:42:08,239 --> 00:42:11,319
Speaker 1: familiar to use like a rubber sheet analogy, where parts

797
00:42:11,360 --> 00:42:13,600
Speaker 1: of space are bent and that changes how an object

798
00:42:13,640 --> 00:42:16,040
Speaker 1: moves sort of naturally. And you know, that's a little

799
00:42:16,040 --> 00:42:19,120
Speaker 1: confusing because in what direction is the rubber sheet bending.

800
00:42:19,120 --> 00:42:22,000
Speaker 1: It's bending in some sort of like external direction. You

801
00:42:22,000 --> 00:42:24,840
Speaker 1: can measure it in terms of like another dimension in reality,

802
00:42:24,840 --> 00:42:28,120
Speaker 1: in our space. It's intrinsic curvature. It just changes the

803
00:42:28,200 --> 00:42:32,040
Speaker 1: relationship between points in space their relative distances. So that's

804
00:42:32,040 --> 00:42:34,920
Speaker 1: a familiar way to think about how the curvature space

805
00:42:34,960 --> 00:42:38,080
Speaker 1: affects the motion of an object. You can do something

806
00:42:38,120 --> 00:42:40,840
Speaker 1: similar for a time. You can imagine like different parts

807
00:42:40,840 --> 00:42:43,680
Speaker 1: of the universe flowing with different time. Right, It's sort

808
00:42:43,680 --> 00:42:46,479
Speaker 1: of like you're moving down a river and different parts

809
00:42:46,480 --> 00:42:48,960
Speaker 1: of the river are moving faster than others, and that

810
00:42:49,000 --> 00:42:51,400
Speaker 1: will affect the motion of objects. Like you have a

811
00:42:51,440 --> 00:42:54,040
Speaker 1: really big object in a river and the river is

812
00:42:54,040 --> 00:42:56,280
Speaker 1: flowing faster on the left side than on the right side.

813
00:42:56,400 --> 00:42:58,560
Speaker 1: It's going to change the way that object moves it

814
00:42:58,760 --> 00:43:01,880
Speaker 1: like tug it towards it's the slow moving part of

815
00:43:01,880 --> 00:43:05,640
Speaker 1: the river, and that's part of how the curvature space

816
00:43:05,680 --> 00:43:09,319
Speaker 1: and time creates this effect of gravity that objects no

817
00:43:09,360 --> 00:43:12,000
Speaker 1: longer move in what we perceive to be straight lines.

818
00:43:12,200 --> 00:43:13,759
Speaker 1: I see you're saying, like you can think of it

819
00:43:13,800 --> 00:43:16,480
Speaker 1: the other way around, Like me falling to the Earth

820
00:43:16,920 --> 00:43:19,680
Speaker 1: or me being an orbit around Earth is actually a

821
00:43:19,680 --> 00:43:23,600
Speaker 1: consequence of the differences in time, and like differences in

822
00:43:23,680 --> 00:43:26,480
Speaker 1: time cause me to move from one place to another, exactly,

823
00:43:26,680 --> 00:43:31,480
Speaker 1: it's space and time being heard, both affect your trajectory. Cool,

824
00:43:31,600 --> 00:43:34,680
Speaker 1: So in a way, asking why does gravity slow down time,

825
00:43:34,800 --> 00:43:39,040
Speaker 1: you could also mainly ask why does time slowing downtime

826
00:43:39,080 --> 00:43:41,880
Speaker 1: cause gravity? Yeah, exactly. Another way to think about it

827
00:43:41,920 --> 00:43:45,080
Speaker 1: is that the effective gravity we observe is coming from

828
00:43:45,160 --> 00:43:47,520
Speaker 1: the curvature space and the curvature of time, and that

829
00:43:47,840 --> 00:43:51,800
Speaker 1: gravitational time dilation is just another aspect of the curving

830
00:43:52,000 --> 00:43:54,800
Speaker 1: of space time in respect to mass. So I guess

831
00:43:54,840 --> 00:43:56,359
Speaker 1: in the end, you just have to say that it's

832
00:43:56,480 --> 00:43:59,400
Speaker 1: all sort of kind of the same thing. It's all

833
00:43:59,480 --> 00:44:01,319
Speaker 1: sort of relate it in and it's all you know.

834
00:44:01,360 --> 00:44:03,560
Speaker 1: You can look at it from one way, or you

835
00:44:03,560 --> 00:44:05,359
Speaker 1: can look at it upside down. But at the end

836
00:44:05,400 --> 00:44:07,440
Speaker 1: of the day, and it all comes down to really

837
00:44:07,480 --> 00:44:10,920
Speaker 1: I think exceloration, right, Like things that accelerate have to

838
00:44:10,960 --> 00:44:13,600
Speaker 1: slow down in time because of the speed limit of

839
00:44:13,600 --> 00:44:16,000
Speaker 1: the universe. Yeah, that's a consistent way to think about it.

840
00:44:16,160 --> 00:44:18,400
Speaker 1: I prefer the sort of geometrical way to think about it,

841
00:44:18,400 --> 00:44:20,719
Speaker 1: that we're living in a universe that's courage and work,

842
00:44:20,800 --> 00:44:23,200
Speaker 1: but we don't perceive it directly, and so the way

843
00:44:23,239 --> 00:44:26,480
Speaker 1: things move through space and time are affected by these

844
00:44:26,520 --> 00:44:29,680
Speaker 1: like invisible warping. That sort of geometrically makes the most

845
00:44:29,680 --> 00:44:31,160
Speaker 1: sense to me. But you can also think about it

846
00:44:31,200 --> 00:44:34,839
Speaker 1: just in terms of acceleration in flat space. Yeah, all right, Well,

847
00:44:34,880 --> 00:44:36,759
Speaker 1: I guess that answer is sort of the question why

848
00:44:36,800 --> 00:44:39,880
Speaker 1: does gravity slow down time? The answer is because of

849
00:44:39,920 --> 00:44:43,360
Speaker 1: exploration and why does exceleraation slow than time? Well, we

850
00:44:43,520 --> 00:44:46,160
Speaker 1: probably need a whole new podcast episode about it. Yeah,

851
00:44:46,160 --> 00:44:48,640
Speaker 1: why does gravity slow down time? Because time is bent

852
00:44:48,880 --> 00:44:52,440
Speaker 1: in the presence of mass, just like spaces. I think

853
00:44:52,440 --> 00:44:56,680
Speaker 1: you just went all the way around. Why does the

854
00:44:56,680 --> 00:45:00,080
Speaker 1: excelation slow in time because slowing downtime causes excelraation. It

855
00:45:00,120 --> 00:45:02,719
Speaker 1: sounds like a great answer, and it causes podcasts to

856
00:45:02,760 --> 00:45:04,719
Speaker 1: go in circles. Yeah, and now you can just hit

857
00:45:04,800 --> 00:45:08,160
Speaker 1: replay and listen to this episode all over again and

858
00:45:08,360 --> 00:45:10,760
Speaker 1: it should make sense. Right. It's all pretty tricky stuff.

859
00:45:10,800 --> 00:45:13,160
Speaker 1: In the end, it all comes down to consequences from

860
00:45:13,160 --> 00:45:16,320
Speaker 1: our observation that the speed of light is the maximum

861
00:45:16,360 --> 00:45:18,440
Speaker 1: speed of the universe that just happens to be the

862
00:45:18,520 --> 00:45:20,399
Speaker 1: universe we live in. And when we build in those

863
00:45:20,440 --> 00:45:23,480
Speaker 1: constraints into our theories, these are all the consequences that

864
00:45:23,520 --> 00:45:25,040
Speaker 1: come out of it. And maybe that point is what

865
00:45:25,120 --> 00:45:27,160
Speaker 1: you were saying earlier than you know. We have the

866
00:45:27,280 --> 00:45:30,719
Speaker 1: speed limit and it causes time to do weird things.

867
00:45:30,719 --> 00:45:33,440
Speaker 1: So maybe time is not a fundamental thing, right, Like

868
00:45:33,480 --> 00:45:37,360
Speaker 1: it's not outside of the universe. Maybe time it's something

869
00:45:37,400 --> 00:45:40,400
Speaker 1: that comes out of how the universe works, yeah, or

870
00:45:40,440 --> 00:45:43,239
Speaker 1: how we are perceiving it or measuring it. And you know,

871
00:45:43,280 --> 00:45:46,879
Speaker 1: there's a whole universe of crazy ideas about time, even

872
00:45:46,960 --> 00:45:49,160
Speaker 1: ideas that like time is not essential part of the

873
00:45:49,239 --> 00:45:51,480
Speaker 1: universe but comes out of something else, or that there

874
00:45:51,520 --> 00:45:54,720
Speaker 1: are multiple dimensions of time, the way there are multiple

875
00:45:54,719 --> 00:45:57,799
Speaker 1: dimensions of space, and we're just moving on like a

876
00:45:57,960 --> 00:46:02,120
Speaker 1: one D line through threedom mentional time. Man, there's a

877
00:46:02,160 --> 00:46:05,759
Speaker 1: whole like crazy, crazy set of really fun ideas to

878
00:46:05,800 --> 00:46:08,560
Speaker 1: dig into. Unfortunately we are out of time for this episode.

879
00:46:09,280 --> 00:46:11,920
Speaker 1: We'll have to find more time to get into it more.

880
00:46:12,080 --> 00:46:14,480
Speaker 1: But we hope you enjoyed that and maybe got you

881
00:46:14,520 --> 00:46:17,359
Speaker 1: to think a little bit more about how young your

882
00:46:17,400 --> 00:46:19,520
Speaker 1: feet are and how you should maybe do more handstand

883
00:46:19,680 --> 00:46:21,480
Speaker 1: I want to see that video if you're doing a handstand,

884
00:46:22,520 --> 00:46:24,759
Speaker 1: I can do what actually, but now it's not the time,

885
00:46:24,840 --> 00:46:27,640
Speaker 1: all right, Well, thanks for joining us, see you next time.

886
00:46:35,400 --> 00:46:38,200
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

887
00:46:38,280 --> 00:46:41,520
Speaker 1: the Universe is a production of I Heart Radio or More.

888
00:46:41,600 --> 00:46:44,600
Speaker 1: Podcast for my Heart Radio, visit the I Heart Radio

889
00:46:44,640 --> 00:46:48,680
Speaker 1: Apple Apple Podcasts, or wherever you listen to your favorite shows.