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Speaker 1: Hey, we're hey. When did you get up today? How

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Speaker 1: do you know I got up? I could be recording

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Speaker 1: this from my bed right now. Thanks for that mental image.

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Speaker 1: Now I kind of regret asking. And even if I'm

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Speaker 1: in bed, I'm technically still moving. Really is your bed

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Speaker 1: on wheels or something, or you have like a flying bed?

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Speaker 1: That would be exciting, But no, I'm on Earth and

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Speaker 1: the Earth is spinning right in space and it's also

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Speaker 1: flying around the Sun. So I'm still moving right? Did

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Speaker 1: that count? I mean, does your fitbit give you steps forth? Well?

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Speaker 1: I don't really believe in fitbits. I believe in that bits.

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Speaker 1: I have one to make one for cartoonists. Hi am

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Speaker 1: rhand Ma cartoonists and the creator PhD Comics. I'm Daniel.

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Speaker 1: I'm a particle physicist and a professor. You see Irvine

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Speaker 1: and it feels like I'm always in motion. Oh yeah,

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Speaker 1: like your mental gears are always turning or one of

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Speaker 1: those people that have worked on a treadmill all the time. No,

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Speaker 1: I definitely do not work on a treadmill. I work

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Speaker 1: on a chair and I lean way back with a crazy,

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Speaker 1: ridiculous posture that would make like any ergonomic specialist cringe.

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Speaker 1: And that's what you mean by motion, that's your workout,

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Speaker 1: leaning back for a nap. No, I mean that's sort

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Speaker 1: of always scrambling from one thing to the other, working

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Speaker 1: on this. Oops, that's late running over here. It feels

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Speaker 1: like being an adult in today's modern world is always

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Speaker 1: scrambling from one thing to another. You know what you mean.

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Speaker 1: But you do know you have a choice there, Daniel,

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Speaker 1: I could retire early, Yeah, you can. You cannot do

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Speaker 1: so many things that who would I even be? Man?

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Speaker 1: Who would I even be? Welcome to existential questions with

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Speaker 1: Daniel and Jorge, No, but seriously, welcome to a podcast

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Speaker 1: Daniel and Hojorge Explain the Universe, a production of I

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Speaker 1: Heart Radio in which we do delve into the deepest

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Speaker 1: of exist to questions why does the universe exist? How

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Speaker 1: does it all work? What is our place in it?

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Speaker 1: How long will it last? How will it end? And

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Speaker 1: whose fault will it be when it finally goes poof?

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Speaker 1: In which we dig deep into the very smallest, tiniest

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Speaker 1: little bits of that universe, asked the basic questions about

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Speaker 1: how everything works, and explain all of the answers as

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Speaker 1: far as we know them to you. Yeah, because It

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Speaker 1: is a confusing and vast universe, and it's a pretty

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Speaker 1: restless universe. It seems to be always in motion. There's

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Speaker 1: always something going on in the university because you know,

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Speaker 1: it's so big, and there's always I don't know, and

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Speaker 1: exploding stars somewhere. There's planet spinning everywhere, asteroids flying through

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Speaker 1: the sky. It does seem to be sort of in

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Speaker 1: slow motion violence. You know, you look out into the

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Speaker 1: night sky and you just sort of glance at it,

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Speaker 1: and it seems static. It's not like the stars are

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Speaker 1: whizzing around in front of your eyes. But you know,

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Speaker 1: you pay attention, you see the night sky slide by,

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Speaker 1: and the longer you watch, the more you notice that,

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Speaker 1: like crazy stuff is happening out there, that the explosions

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Speaker 1: that take millions of years but are still very dramatic.

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Speaker 1: So everything up there is actually in motion. We just

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Speaker 1: sort of live in a tiny little burst of time

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Speaker 1: where things seem to be stationary. Yeah, and there's not

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Speaker 1: just a lot of action going on out there. There's

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Speaker 1: a lot of action inside of us. And in the

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Speaker 1: smallest of particles, everything is always you know, vibrating or

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Speaker 1: spinning or quantum spitting or disappearing and appearing at the

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Speaker 1: same time. Yeah, you're right. Quantum mechanics says that everything

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Speaker 1: is in motion and has to be in motion, that

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Speaker 1: nothing can actually come to rest, that nothing in the

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Speaker 1: end can really have no energy. So the very nature

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Speaker 1: of our existence seems to be in motion. Yeah, and

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Speaker 1: it does seem like nowadays live involves a lot of

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Speaker 1: moving around. You know, it seems like things are spinning

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Speaker 1: and moving and changing faster than we can you know,

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Speaker 1: get ahold of it. And so you know, the idea

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Speaker 1: of resting or being motionless, or you know, just stopping

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Speaker 1: and not doing anything is it's kind of weird, right,

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Speaker 1: maybe to a lot of people. Yeah, maybe that. I

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Speaker 1: think a lot of people did more of that in

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Speaker 1: this life last year than they're used to. Went to

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Speaker 1: fewer places, canceled traveling, didn't go to the office as much.

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Speaker 1: So a lot of people were sort of stuck in

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Speaker 1: a smaller orbit than they usually are by the pandemic.

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Speaker 1: But still everybody is still moving. Yeah, it's been kind

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Speaker 1: of a tough year for everybody, but it's still fun

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Speaker 1: to kind of think about the universe and all the

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Speaker 1: things that are going on inside of it, and we

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Speaker 1: especially like to ask interesting questions in this podcast about

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Speaker 1: you know, what's theoretically possible and what is theoretically impossible

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Speaker 1: or what is theoretically nonsensical. That's right, and we're not

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Speaker 1: the only ones wondering about those kinds of questions. All

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Speaker 1: of our listeners are out there thinking about the nature

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Speaker 1: of the universe and what's possible and what their experience

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Speaker 1: is like in it. And a lot of people right

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Speaker 1: in with a particular question when they notice that everything

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Speaker 1: in the universe seems to be moving. Everything is sliding

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Speaker 1: or spinning or orbiting or zooming through space. And I

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Speaker 1: think this inspires people to ask this particular question about

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Speaker 1: whether motionlessness is possible. Yeah, so to be on the podcast,

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Speaker 1: we'll be tackling the question can you be motionless in space? Now? Daniel,

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Speaker 1: do you think people are you know, being aspirational with

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Speaker 1: this question, like how can I be motionless in space?

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Speaker 1: Or are they asking you think the theoretical question is

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Speaker 1: is it possible to be not moving at all in

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Speaker 1: this universe? I don't think anybody is asking a practical question.

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Speaker 1: I don't think they're trying to develop one of those

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Speaker 1: like extreme isolation pods where you can float out in

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Speaker 1: space and have nothing touch you or anything like that.

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Speaker 1: I think people are pushing the envelopes because they want

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Speaker 1: to know what's possible. So in that sense, I guess

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Speaker 1: it's a theoretical question. Just like in our Extreme Universe

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Speaker 1: podcast episodes, sometimes you learn something about the nature of

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Speaker 1: space by looking at the extreme situation, asking what's the

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Speaker 1: fastest you can go or what's the slowest you can go,

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Speaker 1: what's the hottest something can be, what's the coldest something

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Speaker 1: can be. So since everything seems to be moving, I

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Speaker 1: think people are wondering is it even post the all

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Speaker 1: theoretically for something to be totally at rest? What would

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Speaker 1: that mean, what would it require? What does it reveal

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Speaker 1: about the nature of the universe? Right? Yeah, Still I

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Speaker 1: mean to think that a physicist might ask a practical question.

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Speaker 1: Sorry about that, but it is a pretty interesting theoretical question,

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Speaker 1: like can you be not moving? I guess, And do

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Speaker 1: you think that's more about staying still or a feeling

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Speaker 1: that you're not moving? Do you know what I mean? Like,

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Speaker 1: do you think people are asking about is there a

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Speaker 1: point in the universe that's technically not moving relative to

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Speaker 1: everything else? Or do you think it means just like,

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Speaker 1: how can I not have an emotion relative to anything else? Yeah,

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Speaker 1: I think there's a lot of interesting stuff to unpack

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Speaker 1: there about like the very nature of what it means

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Speaker 1: to be in motion, that we're going to have to

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Speaker 1: dig into, because I think something about this question reveals

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Speaker 1: that people are thinking about speed in a way that

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Speaker 1: comes naturally to them on the surface of the Earth,

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Speaker 1: where it makes sense to talk about what my speed is.

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Speaker 1: But when you go out into space, things change. Things

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Speaker 1: are different the same way that like up and down

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Speaker 1: have a meaning on the surface of the Earth but

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Speaker 1: don't really make sense anymore out in space. I think

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Speaker 1: we're going to learn that the whole concept of velocity

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Speaker 1: is a little bit different than what a lot of

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Speaker 1: people had in mind. And so this is a great question,

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Speaker 1: not because the answer is simple and reveals the truth

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Speaker 1: about the universe, but because the nature of the question

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Speaker 1: makes you rethink the whole nature of motion. Yeah, and

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Speaker 1: then you have to ask the follow up question, which

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Speaker 1: is can you be emotionless in space? After learning the

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Speaker 1: answer to the first question, I think we know the

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Speaker 1: answer that it's called the movie gravity. Oh, movie criticism

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Speaker 1: and physics all in one podcast. Seriously, nobody seems to

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Speaker 1: have any emotions in the movie. They're all just like stoic,

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Speaker 1: just trying to not die. I think in space? Can

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Speaker 1: you be alive in space? That's the question they were asking,

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Speaker 1: not just standing still because you're dead. But yeah, this

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Speaker 1: is a pretty interesting question, and so, as usually, we

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Speaker 1: were wondering how many people out there have thought about

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Speaker 1: this question and whether or not they have an answer

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Speaker 1: that they might have thought of. Daniel went out there

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Speaker 1: into the internet to ask the question, Shan, can you

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Speaker 1: be motionless in space? That's right, I go out into

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Speaker 1: the web and beat the bushes for people who are

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Speaker 1: interested in answering these questions for us. If you are

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Speaker 1: out there on the internet and have not participated, please

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Speaker 1: we want to hear your voice, especially if you're from

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Speaker 1: a location we haven't heard anybody from before. We would

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Speaker 1: love to hear your voice on the podcast, So please

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Speaker 1: write to us two questions at Daniel and Jorge dot com.

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Speaker 1: So think about it for a second. Do you think

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Speaker 1: it's possible to be motionless in space? Here's what people

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Speaker 1: had to say. Well, I can be motionless if I

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Speaker 1: don't move a muscle, So nothing on me would move,

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Speaker 1: that would qualify as motionless, I guess, But relative to

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Speaker 1: something else, I would probably never be motionless because everything

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Speaker 1: else is moving. The Sun is moving around the center

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Speaker 1: of the galaxy, and the planets around the Sun, everything

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Speaker 1: else is moving. Even space itself is expanding. So even

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Speaker 1: if I'm in a point in space and the space

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Speaker 1: around me is expanding, then the things around me would

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Speaker 1: be moving along with it as well. So can you

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Speaker 1: be motionless in space? Yes, if I don't move a muscle. No,

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Speaker 1: relative to anything else, I don't think you can be

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Speaker 1: motionless in space. If two bodies are passing by each

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Speaker 1: other and neither is accelerating, both bodies, from their perspective

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Speaker 1: would feel that they were standing still and the other

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Speaker 1: one was moving. It doesn't seem like it, since your

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Speaker 1: motion would be relative to whatever it was around you.

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Speaker 1: So even if you're standing still on Earth, the Earth

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Speaker 1: is spinning and moving around the Sun, And if you're

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Speaker 1: standing still next to the Sun, it's spinning around the

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Speaker 1: galaxy and the galaxy is moving. Um, but maybe it's

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Speaker 1: possible to just stick still with respect to the the

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Speaker 1: fabric of space. Well, if I'm not moving at all, yes,

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Speaker 1: But motionless like not moving from the we really regard

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Speaker 1: into something like the moon, Earth's sun, galaxy, the galaxy

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Speaker 1: cluster Lannique, and so on. Probably I would be moving.

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Speaker 1: Motion is relative, measured relatively to other things. So I

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Speaker 1: guess you could technically you would always be motionless and

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Speaker 1: always be moving in all different directions at the same time.

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Speaker 1: With space expanding, I don't know if that becomes a

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Speaker 1: factor too, but probably does. I don't think that you

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Speaker 1: can be motionless in space. I think that there's a

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Speaker 1: reason why Einstein thought up the theory of relativity, because

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Speaker 1: there is no super position that we can use to

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Speaker 1: compare positions in space against. You've only really got what

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Speaker 1: you have, which is your own frame of reference, and

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Speaker 1: then you compare that to something else. And because everybody

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Speaker 1: else has a different reference, there is no set central

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Speaker 1: position where something is not moving. If I somehow ended

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Speaker 1: up in space and I wasn't moving for some reason, um,

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Speaker 1: according to which one Newton's first law, UM, an object

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Speaker 1: that is not moving, we'll stay stationary. UM. So I

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Speaker 1: suppose if somehow, I don't know, if the Earth vanished

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Speaker 1: and I was left suspended in space, UM, and I

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Speaker 1: wasn't moving, then I would be motionless in space, all right.

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Speaker 1: A lot of people there doesn't think to think it's

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Speaker 1: possible to be motionless. Yeah, yeah, exactly, It's it's fascinating.

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Speaker 1: I think people are just naturally reathless or they have

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Speaker 1: one of those restless leg syndromes. Yeah, there are those

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Speaker 1: people who are always tapping on something or got like

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Speaker 1: a fidget spinner or something. Yeah, I know what my

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Speaker 1: kids would say. I would say, no, it's impossible right now,

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Speaker 1: what I would say about my children even if they

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Speaker 1: were in space, and the kids would say, like, and

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Speaker 1: why would you want to? That seems really boring, right,

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Speaker 1: just lying there doing nothing. Yeah, So it's an interesting question.

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Speaker 1: I guess the question sort of boils down to, like

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Speaker 1: it's not about standing still, but it's more about moving, right,

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Speaker 1: like your whole body moving somewhere, right, because technically we

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Speaker 1: are always vibrating, right, like if we have a temperature,

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Speaker 1: your our molecules are moving. This is more about, you know,

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Speaker 1: whether we're as a whole dane still or translating or

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Speaker 1: moving or going from one place to another, right. Yeah,

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Speaker 1: I think we should sort of like approximate you as

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Speaker 1: a little dot or a point particle and ignore all

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Speaker 1: the motion inside you, and then ask the question, can

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Speaker 1: point particle, you can spherical? You be motionless with respect

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Speaker 1: to everything? Is that even possible? Right? Like cartoon Jorge,

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Speaker 1: So this should be easy because I'm good at ignoring

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Speaker 1: all the emotions inside of me. Right, that was a

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Speaker 1: little dark. No, I'm just kidding, but yeah, it's about

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Speaker 1: whether or not we're moving in relative or moving in

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Speaker 1: space as a whole. Yeah, exactly. And one of the

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Speaker 1: most important things to understand is that there is no

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Speaker 1: absolute motion. All motion is relative. It's always defined relative

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Speaker 1: to something else. You Know. People writing often and ask

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Speaker 1: questions about like special relativity, and usually their questions start

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Speaker 1: with something like if I was in a spaceship and

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Speaker 1: I was going really really fast, and they don't say

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Speaker 1: what they're going really really fast relative to? You know,

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Speaker 1: they have this sense that like there's something that happens

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Speaker 1: when you get up to high speeds. But the thing

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Speaker 1: that's missing there is like who are you speeding by?

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Speaker 1: Where are you going fast relative to? There is no

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Speaker 1: sense in which you have speed other than that it's

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Speaker 1: measured relative to other things or people, right, Because I

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Speaker 1: guess motion is a quantity that is that can't exists

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Speaker 1: on its own, right, Yeah, exactly. If you are, for example,

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Speaker 1: in an empty universe, right it's just you floating in

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Speaker 1: space and there's nothing else in the universe, then you

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Speaker 1: or speed doesn't make any sense. You have no velocity.

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Speaker 1: You can't have velocity because velocity is just motion relative

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Speaker 1: to something else. You know. I guess this might be

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Speaker 1: confusing to people because I wonder, like, you know, I

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Speaker 1: think a lot of us maybe imagine that, you know,

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Speaker 1: the universe maybe has an extent, like a limit, like

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Speaker 1: a wall at some point. Maybe it's a big sphere,

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Speaker 1: maybe it's a big blob, maybe it's a donut. But

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Speaker 1: it has sort of like a shape of it. So

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Speaker 1: couldn't I measure my speed or my motion relative to

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Speaker 1: that shape? No, because the universe is actually symmetric. Like

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Speaker 1: if you do some experiment over here and then you

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Speaker 1: do the same experiment over there, you always get the

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Speaker 1: same answer. There's no point in space that's different than

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Speaker 1: another point in space, Like space has no texture. There's

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Speaker 1: no like way to tell where you are in space.

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Speaker 1: I mean, it might be that the universe is finite

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Speaker 1: and has some like weird edge to it, but we

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Speaker 1: haven't observed that, and the current cosmological models usually assume

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Speaker 1: that the universe is infinite and that every point in

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Speaker 1: it behaves the same way, Like the laws of physics

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Speaker 1: are the same no matter where you are, and so

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Speaker 1: you can't do an experiment determine where you are. So

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Speaker 1: it's not like you can feel space moving by or

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Speaker 1: measure yourself your location relative to some like absolute point

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Speaker 1: in space. There is no absolute point, and so there

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Speaker 1: is also no absolute velocity. Well, there's no absolute point

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Speaker 1: that we know of, right, But could there be one

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Speaker 1: if like the universe does have a shape or like

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Speaker 1: a wall or limit in some scenarios, yes, in most scenarios, no, Like,

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Speaker 1: even if the universe is not infinite, right, it might

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Speaker 1: not have an edge. Like imagine the universe is closed

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Speaker 1: and finite the way it like wraps around itself. That

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Speaker 1: doesn't mean that there's any special point. It can be

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Speaker 1: finite and still have like no special location to it.

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Speaker 1: Imagine you're like on the surface of a sphere, right,

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Speaker 1: then every point on that sphere is really the same,

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Speaker 1: even though the service is not infinite, right, Yeah, I guess,

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Speaker 1: like if the universe was like at the pag max screen.

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Speaker 1: Then there's technically no real place in the pac Man's

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Speaker 1: screen because it just loops around forever. But I guess

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Speaker 1: I'm just trying to get to the possibly that maybe

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Speaker 1: it does have an edge, in which case there would

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Speaker 1: be something like an absolute position. Right. If the universe

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Speaker 1: did have some sort of like strange wall as an

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Speaker 1: edge to it, or some like deformity in its geometry,

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Speaker 1: then yes, that would break this cosmological principle that every

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Speaker 1: location is the same, and then you could measure your

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Speaker 1: velocity relative to that there would be a special location

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Speaker 1: in space. But still your velocity would only have meaning

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Speaker 1: a relative to something. And you can define your velocity

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Speaker 1: to be relative to like that weird edge of space

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Speaker 1: or the Sun or the moon, or there's dust particle,

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Speaker 1: but the definition of your velocity still only has meaning

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Speaker 1: relative to something, right, Yeah, because I guess you know

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Speaker 1: motion or velocity, it's like the change in a quantity,

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Speaker 1: which is distance. So you can have distance if you

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Speaker 1: don't measure relative to something else, right, yeah, exactly, And

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Speaker 1: this is actually really closely connected to like all sorts

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Speaker 1: of interesting deep physics of the universe. You know the

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Speaker 1: fact that space seems to be the same everywhere. That

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Speaker 1: if you do your experiment here and then you transport

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Speaker 1: it ten light years over there and do it again,

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Speaker 1: that you get the same answer. That's connected to an

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Speaker 1: important law of physics, which is conservation of momentum. And

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Speaker 1: we're gonna do a whole fun podcast episode about this

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Speaker 1: deep theory of physics called Nuther's theorem that tells you

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Speaker 1: that anytime you have a symmetry like that, something where

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Speaker 1: the universe doesn't care where you are, you get some

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Speaker 1: conserved quantity, something which doesn't change as you do your experiments.

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Speaker 1: So in this case, the connection is the fact that

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Speaker 1: you can move from one place in space to another

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Speaker 1: and not have your experiment change. Is why we have

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Speaker 1: conservation of momentum, which is sort of mind blowing to me.

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Speaker 1: But yeah, exactly, velocity is defined relative to other things

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Speaker 1: in space, not relative to space itself, right, And I

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Speaker 1: think it extends not just to like your precision in

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Speaker 1: the universe, right, Like you can do an experiment here

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Speaker 1: or there and it should be worked out the same,

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Speaker 1: but it also it comes up in doing the experiment

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Speaker 1: at different velocities. Right. I can do my experiments going

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Speaker 1: at a hundred moss per hour relative to the Earth,

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Speaker 1: or I can do it at a hundred thousand miles

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Speaker 1: per hour. I should get the same results if I'm

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Speaker 1: going at a constant speed, right, Yeah, exactly. If you're

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Speaker 1: in a box, you can't measure your velocity relative to

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Speaker 1: stuff outside the box if you can't see that stuff

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Speaker 1: at all. So if you do an experiment, it shouldn't

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Speaker 1: be sensitive to your velocity relative to that stuff. So

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Speaker 1: the classic scenario is like you set up some experiment.

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Speaker 1: I don't know what it is. It's got you know,

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Speaker 1: like balls swinging and hitting each other or whatever, and

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Speaker 1: then you gently accelerate up to some higher speed, right,

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Speaker 1: And the key there is gently accelerates so you don't

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Speaker 1: like destroy everything. Now your speed is high relative to

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Speaker 1: like the surface of the Earth or the planet you're

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Speaker 1: on or whatever. You do the same experiment, you should

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Speaker 1: get exactly the same result. And that's not just some

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Speaker 1: like weird esoteric thing that means that you can't measure

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Speaker 1: your velocity. Is no experiment you could do that would

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Speaker 1: give a different answer if your velocity relative to that

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Speaker 1: planet is zero or a thousand meters per second, And

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Speaker 1: that means you can't build a device to measure that velocity. Right,

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Speaker 1: And again this applies to just to double check, this

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Speaker 1: applies to like constant velocity. Right. If I'm accelerating, then

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Speaker 1: that's a whole different ball game, exactly. Acceleration is totally different,

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Speaker 1: which is also really interesting. Acceleration is something you can measure.

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Speaker 1: There is absolute acceleration. If you're in a box, you

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Speaker 1: can measure your acceleration. Right. You can do a simple

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Speaker 1: experiment toss a ball up in the air and it

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Speaker 1: will move differently if you're under acceleration then if you're not.

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Speaker 1: And also you'll feel it. If you're in a box

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Speaker 1: and it's accelerating, it will feel just like gravity. Right.

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Speaker 1: Acceleration feels just like gravity, which was the whole inside

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Speaker 1: which led to general relativity and that whole revolution and

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Speaker 1: understanding space and time. But position and velocity only makes

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Speaker 1: sense relative to other things, right. And I think what

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Speaker 1: you're saying, basically just to kind of drive this home,

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Speaker 1: is that like, if you're inside of a box out

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Speaker 1: in space, it's sort of impossible to know how fast

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Speaker 1: that box you're in is moving relative to other things. Right.

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Speaker 1: If it's moving at a constant speed, or not. It's

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Speaker 1: impossible to tell that, you know, boxes floating out in

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Speaker 1: space or it's like moving super fast across the galaxy. Yeah, exactly,

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Speaker 1: as long as you can't look outside the box. Like

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Speaker 1: if you have a window, you can look outside and

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Speaker 1: you can see things moving by and measure it. But

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Speaker 1: if all you can do is measure things inside the box,

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Speaker 1: then yeah, you can't measure your velocity relative to anything

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Speaker 1: outside the box. There's no way to tell, right, And

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Speaker 1: so I think what you're getting at is that basically

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Speaker 1: just the word motionless doesn't really have any meaning, right

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Speaker 1: because you might think you're motionless now inside your box,

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Speaker 1: but really you could be moving really fast or not

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Speaker 1: at all, or moving in any kind of crazy direction

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Speaker 1: outside of that box. So really the word motionless doesn't

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Speaker 1: mean anything from a physics math point of view. Yeah,

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Speaker 1: it's either totally meaningless or it's just totally arbitrary. Like

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Speaker 1: you can pick a definition of a reference frame and say,

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Speaker 1: I'm going to say that the Earth is at the

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Speaker 1: center of my reference frame. Now my velocity has meaning.

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Speaker 1: I'm talking about velocity relative to the Earth. But you

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Speaker 1: could also pick anything else. You could pick the sun,

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Speaker 1: you could pick that grain of dust. You could pick

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Speaker 1: a distant comment. Your answer depends on your choice, and

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Speaker 1: your choice is totally arbitrary, and no choice is better

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Speaker 1: than any other. So you can either say velocity is meaningless, right,

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Speaker 1: or you can say it only has meaning when you

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Speaker 1: make an arbitrary choice of what you're measuring it relative to. Right.

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Speaker 1: So basically, when you try to answer the question can

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Speaker 1: you be motionless in space, you're saying that's kind of

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Speaker 1: a nonsensical question, or like an impossible question to ask

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Speaker 1: in terms of the math and in the physics, because

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Speaker 1: there's no way to tell if you are motionless, because

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Speaker 1: it depends on what you measure your motion relative to

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Speaker 1: and it could be anything. It could be anything, and

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Speaker 1: even if you pick something, it would be totally different

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Speaker 1: according to somebody else. Yeah, exactly, Like in some sense

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Speaker 1: the answer is trivial, like, yes, you can be motionless

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Speaker 1: in space if you measure your motion relative to yourself.

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Speaker 1: So by definition, your velocity is zero relative to yourself. Boom,

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Speaker 1: your motionless in space. So that's what I meant when

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Speaker 1: I said, like, this question is interesting because this whole

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Speaker 1: question of velocity, I think people have an intuitive sense

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Speaker 1: of like motion is something that you can measure, but

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Speaker 1: you can't actually measure it in a pure sense. You

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Speaker 1: can only measure relative to other things, and so it

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Speaker 1: becomes kind of arbitrary and unfortunately meaningless. All right, well,

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Speaker 1: I think that's a little counterintuitive because our daily experience

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Speaker 1: is that we are moving on Earth, and the Earth

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Speaker 1: is moving around the Sun, and then the Sun is

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Speaker 1: moving around the galaxy. So let's dig a little bit

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Speaker 1: deeper into these types of motions and then let's try

430
00:22:23,840 --> 00:22:26,800
Speaker 1: to answer whether or not it is actually possible to

431
00:22:26,920 --> 00:22:30,200
Speaker 1: get around that loophole. But first let's take a quick break.

432
00:22:42,359 --> 00:22:44,159
Speaker 1: All right, we're trying to answer the question can you

433
00:22:44,200 --> 00:22:50,200
Speaker 1: be motionless in space? And the answer is um, yes

434
00:22:50,280 --> 00:22:52,920
Speaker 1: and no, or or ask a better question? Is the

435
00:22:52,960 --> 00:22:56,680
Speaker 1: answer it's yes according to our legal department, as long

436
00:22:56,720 --> 00:23:00,399
Speaker 1: as you define a reference brain right, because idea is

437
00:23:00,440 --> 00:23:02,760
Speaker 1: that you know, I can always say emotionless relative to

438
00:23:02,920 --> 00:23:05,240
Speaker 1: whatever box I'm in, but you know who knows what

439
00:23:05,359 --> 00:23:09,040
Speaker 1: this box is moving relative to? Yeah, And that's sort

440
00:23:09,080 --> 00:23:13,160
Speaker 1: of like the abstract theoretical answer, and it's unsatisfying because

441
00:23:13,280 --> 00:23:16,959
Speaker 1: there are some reasonable choices you can make, right in theory,

442
00:23:17,400 --> 00:23:19,720
Speaker 1: what reference frame you pick to measure your motion is

443
00:23:19,760 --> 00:23:22,879
Speaker 1: totally arbitrary and and there's no one preferred over others.

444
00:23:23,040 --> 00:23:25,480
Speaker 1: But there are things around us that it makes sense

445
00:23:25,520 --> 00:23:27,919
Speaker 1: to define your motion relative to. Right, you know, we

446
00:23:28,000 --> 00:23:30,560
Speaker 1: have the Earth, we have the Sun, we have the galaxy,

447
00:23:30,680 --> 00:23:34,560
Speaker 1: and it's fascinating how we are moving relative to those things. Yeah,

448
00:23:34,640 --> 00:23:36,920
Speaker 1: and it's not a little bit of motion. We're going

449
00:23:37,119 --> 00:23:40,639
Speaker 1: pretty fast right here on Earth. So what like, let's

450
00:23:40,760 --> 00:23:43,080
Speaker 1: maybe take it one step at a time. What if

451
00:23:43,119 --> 00:23:46,119
Speaker 1: I define our emotion as relative to the Earth or

452
00:23:46,160 --> 00:23:48,880
Speaker 1: the center of the Earth, how fast are we moving? Yeah? Right,

453
00:23:48,960 --> 00:23:50,680
Speaker 1: relative to the Earth or the center of the Earth.

454
00:23:50,680 --> 00:23:52,960
Speaker 1: Those are two different things. If you say, what's my

455
00:23:53,040 --> 00:23:56,640
Speaker 1: motion relative to this patch of earth underneath my feet, Well,

456
00:23:56,680 --> 00:23:58,879
Speaker 1: if you're just standing on it, then it's obviously zero.

457
00:23:59,240 --> 00:24:01,680
Speaker 1: But if you say, what's my motion relative to the

458
00:24:01,800 --> 00:24:04,639
Speaker 1: very center of the Earth, then you have to measure

459
00:24:04,640 --> 00:24:06,919
Speaker 1: the spinning of the Earth, right, Because the Earth is

460
00:24:06,960 --> 00:24:09,520
Speaker 1: not just a ball of rock moving through space. It's

461
00:24:09,560 --> 00:24:13,240
Speaker 1: also spinning, spinning pretty quickly like it's a big rock,

462
00:24:13,520 --> 00:24:16,960
Speaker 1: and it spins once every twenty four hours, so that's

463
00:24:17,000 --> 00:24:20,160
Speaker 1: pretty high speed. You know, at the equator, for example,

464
00:24:20,359 --> 00:24:24,600
Speaker 1: the surface of the Earth is moving at six kilometers

465
00:24:24,680 --> 00:24:27,359
Speaker 1: per hour relative to the center of the Earth, And

466
00:24:27,440 --> 00:24:30,119
Speaker 1: of course that depends on your latitude, because at the

467
00:24:30,119 --> 00:24:32,320
Speaker 1: north pole it's not moving at all, and at the

468
00:24:32,320 --> 00:24:34,199
Speaker 1: south pole is not moving at all, and at the

469
00:24:34,200 --> 00:24:37,960
Speaker 1: equator it has that maximum speed. Right, Although I wonder

470
00:24:38,000 --> 00:24:39,920
Speaker 1: if you're committing the same error that we were pointing

471
00:24:39,920 --> 00:24:42,080
Speaker 1: out earlier, because you just said the Earth is spinning

472
00:24:42,080 --> 00:24:44,560
Speaker 1: really fast, But don't you have to say what it's

473
00:24:44,560 --> 00:24:48,320
Speaker 1: spinning fast relative to? Yeah, exactly, like, couldn't the whole universe,

474
00:24:48,480 --> 00:24:51,879
Speaker 1: like strange coincidence, be spinning kind of at the same

475
00:24:51,960 --> 00:24:55,000
Speaker 1: rate the Earth is, in which case we're not really spinning. Yes,

476
00:24:55,080 --> 00:24:58,320
Speaker 1: And here we're talking about spinning relative to the center

477
00:24:58,359 --> 00:25:00,960
Speaker 1: of the Earth. Right, when you talk about spin, you

478
00:25:01,040 --> 00:25:04,280
Speaker 1: have to pick an axis around which you're spinning. And

479
00:25:04,320 --> 00:25:07,120
Speaker 1: so you're right that there's no like preferred access there.

480
00:25:07,280 --> 00:25:09,399
Speaker 1: And that's actually a really interesting question I want to

481
00:25:09,400 --> 00:25:11,879
Speaker 1: get into in a future episode. But whether or not

482
00:25:12,000 --> 00:25:14,960
Speaker 1: the whole universe is spinning, or whether the Earth is spinning,

483
00:25:15,080 --> 00:25:17,840
Speaker 1: it's a deep question called mocks principle that we should

484
00:25:17,880 --> 00:25:19,919
Speaker 1: dig into. But you're right, you need to pick a

485
00:25:20,040 --> 00:25:22,560
Speaker 1: reference frame there. So here we've picked the center of

486
00:25:22,600 --> 00:25:25,040
Speaker 1: the Earth, or more specifically, if we're talking about spinning,

487
00:25:25,320 --> 00:25:27,800
Speaker 1: an access that goes from the north to the south

488
00:25:27,880 --> 00:25:31,720
Speaker 1: pole right, So we're spinning really fast relative to that access,

489
00:25:31,800 --> 00:25:34,960
Speaker 1: and maybe a common question might be like, why don't

490
00:25:34,960 --> 00:25:37,840
Speaker 1: we feel that motion? Like you know, if I sit

491
00:25:37,880 --> 00:25:40,080
Speaker 1: in a Merry Go round or one of those state

492
00:25:40,160 --> 00:25:42,639
Speaker 1: fair rights that spin your round, I definitely feel that,

493
00:25:42,960 --> 00:25:45,359
Speaker 1: But we don't feel this crazy spinning of the earth

494
00:25:45,440 --> 00:25:47,880
Speaker 1: right now. Yeah, it's really interesting. And if you dig

495
00:25:47,920 --> 00:25:51,240
Speaker 1: back into history, as science was sort of like figuring

496
00:25:51,280 --> 00:25:54,080
Speaker 1: out that the Earth was spinning, that it was moving

497
00:25:54,080 --> 00:25:56,760
Speaker 1: in this way, people realize this and they're like, well,

498
00:25:56,800 --> 00:25:59,800
Speaker 1: that's ridiculous, Like if the Earth was spinning that fast,

499
00:26:00,000 --> 00:26:02,679
Speaker 1: you would definitely feel it, wouldn't we And so it

500
00:26:02,760 --> 00:26:05,280
Speaker 1: was counted to people's impressions like when don't we fly

501
00:26:05,400 --> 00:26:08,320
Speaker 1: off into space? Right? And the answer is yes, we

502
00:26:08,359 --> 00:26:11,000
Speaker 1: would fly off into space if the Earth was spinning faster,

503
00:26:11,200 --> 00:26:12,760
Speaker 1: you know, like if you speed up a Merry Go

504
00:26:12,960 --> 00:26:15,320
Speaker 1: round and you can't hold on anymore, then you fly

505
00:26:15,400 --> 00:26:17,560
Speaker 1: off the Merry go round. Well, what's happening here on

506
00:26:17,640 --> 00:26:20,600
Speaker 1: Earth is that we are spinning, like gravity is holding

507
00:26:20,680 --> 00:26:22,920
Speaker 1: us down to the surface of the Earth, and gravity

508
00:26:23,000 --> 00:26:26,239
Speaker 1: is more powerful than that's tripetal force. And also the

509
00:26:26,240 --> 00:26:30,119
Speaker 1: Earth's spin is very very smooth and doesn't change. Like

510
00:26:30,280 --> 00:26:33,000
Speaker 1: the Earth was spinning up and slowing down all the time,

511
00:26:33,160 --> 00:26:36,160
Speaker 1: then you would definitely notice that. But because it's very

512
00:26:36,200 --> 00:26:39,400
Speaker 1: nearly constant, it just sort of gets like subtracted out

513
00:26:39,480 --> 00:26:42,439
Speaker 1: from the gravity that you feel. Like you feel gravity, right,

514
00:26:42,480 --> 00:26:44,640
Speaker 1: it's holding you to the Earth. You notice it. If

515
00:26:44,640 --> 00:26:48,040
Speaker 1: the Earth wasn't spinning, there would be more effective gravity,

516
00:26:48,080 --> 00:26:50,880
Speaker 1: Like gravity would feel stronger if the Earth wasn't spinning.

517
00:26:51,080 --> 00:26:53,159
Speaker 1: So you are feeling the spinning of the Earth as

518
00:26:53,160 --> 00:26:56,000
Speaker 1: a sort of like slight lessening of the gravity you feel,

519
00:26:56,000 --> 00:26:58,800
Speaker 1: but it doesn't change very much you don't notice, right,

520
00:26:58,960 --> 00:27:00,879
Speaker 1: which you just made me think that like if the

521
00:27:00,880 --> 00:27:04,000
Speaker 1: Earth wasn't spinning, we would all weigh a little bit more, yeah,

522
00:27:04,200 --> 00:27:06,840
Speaker 1: like we would feel gravity, we would be heavier. Yes,

523
00:27:06,840 --> 00:27:09,160
Speaker 1: and you do weigh more at the north pole than

524
00:27:09,200 --> 00:27:11,240
Speaker 1: you do at the equator, but only by a very

525
00:27:11,240 --> 00:27:14,040
Speaker 1: small amount. And that's why you don't typically notice these things.

526
00:27:14,119 --> 00:27:15,960
Speaker 1: And that's why the whole sense that the Earth is

527
00:27:16,000 --> 00:27:19,280
Speaker 1: spinning underneath us feels weird because it's not something you

528
00:27:19,280 --> 00:27:22,800
Speaker 1: can intuitively grasp, right. But I think, you know, I

529
00:27:22,840 --> 00:27:24,520
Speaker 1: think you sort of hit on it when you said

530
00:27:24,520 --> 00:27:26,880
Speaker 1: that the Earth is spinning really smoothly, like like that's

531
00:27:26,920 --> 00:27:29,639
Speaker 1: I think that's one reason why we don't feel this

532
00:27:29,720 --> 00:27:33,280
Speaker 1: crazy spinning. But I think maybe the other part of

533
00:27:33,280 --> 00:27:35,520
Speaker 1: it is that it's it's not kind of like a

534
00:27:35,560 --> 00:27:39,919
Speaker 1: perfect motion system, right, Like we still do technically feel

535
00:27:40,040 --> 00:27:43,040
Speaker 1: things like koreolitis acceloration, right, and and things that would

536
00:27:43,040 --> 00:27:44,760
Speaker 1: happen if you were kind of in a merry go

537
00:27:44,840 --> 00:27:47,240
Speaker 1: around trying to get to the center or trying to

538
00:27:47,280 --> 00:27:50,080
Speaker 1: move around and merry go around. We technically still feel

539
00:27:50,080 --> 00:27:53,160
Speaker 1: those weird forces that they're just kind of small relative

540
00:27:53,200 --> 00:27:54,919
Speaker 1: to the size of the Earth. Absolutely, you can do

541
00:27:55,000 --> 00:27:57,879
Speaker 1: experiments to prove that the Earth is spinning because a

542
00:27:58,040 --> 00:28:01,320
Speaker 1: rotating reference frame is not inertial reference frame for you

543
00:28:01,400 --> 00:28:04,120
Speaker 1: special relativity wonks out there, and so you can definitely

544
00:28:04,119 --> 00:28:07,480
Speaker 1: detect that what happens when you have a reference frame

545
00:28:07,640 --> 00:28:11,439
Speaker 1: that's accelerating and when you're spinning that's acceleration because you

546
00:28:11,480 --> 00:28:14,119
Speaker 1: need a force towards the center of the spinning What

547
00:28:14,200 --> 00:28:16,639
Speaker 1: happens when your reference frame is spinning is that you

548
00:28:16,680 --> 00:28:19,680
Speaker 1: get some apparent force. It feels like there's some force

549
00:28:19,800 --> 00:28:22,320
Speaker 1: doing something, even though it's just duty your spinning. And

550
00:28:22,359 --> 00:28:25,440
Speaker 1: here on Earth that's the Coriolis force. And so, for example,

551
00:28:25,480 --> 00:28:27,639
Speaker 1: if you drop a rock from the top of a

552
00:28:27,720 --> 00:28:30,400
Speaker 1: very tall tower, you can measure how far it moves

553
00:28:30,440 --> 00:28:32,520
Speaker 1: sort of sideways in a way that it wouldn't if

554
00:28:32,520 --> 00:28:34,720
Speaker 1: the Earth wasn't spinning. You know, it moves like a

555
00:28:34,760 --> 00:28:36,919
Speaker 1: couple of centimeters when it falls like a hundred and

556
00:28:36,920 --> 00:28:39,440
Speaker 1: fifty meters. So it's a small and subtle effect, but

557
00:28:39,480 --> 00:28:41,440
Speaker 1: you definitely can measure it, and it would be more

558
00:28:41,520 --> 00:28:44,479
Speaker 1: dramatic if the Earth sped up. Interesting, So, like if

559
00:28:44,480 --> 00:28:46,440
Speaker 1: you went up to the top of the tall tower

560
00:28:46,720 --> 00:28:48,720
Speaker 1: and you drop the rock, it wouldn't fall straight down.

561
00:28:48,880 --> 00:28:51,200
Speaker 1: It would sort of curve in this weird way because

562
00:28:51,240 --> 00:28:53,720
Speaker 1: the Earth is spinning. Yeah, exactly. Like imagine you're back

563
00:28:53,760 --> 00:28:55,560
Speaker 1: on that Merry Go Round and you want to throw

564
00:28:55,560 --> 00:28:58,000
Speaker 1: a ball to your friend who's in a different spot

565
00:28:58,000 --> 00:29:00,280
Speaker 1: on the Merry go Round. You can't act you just

566
00:29:00,320 --> 00:29:03,200
Speaker 1: throw it in a straight line towards your friend, because

567
00:29:03,240 --> 00:29:05,200
Speaker 1: by the time the ball gets there, your friend will

568
00:29:05,240 --> 00:29:08,240
Speaker 1: have like rotated away. So if you want to throw

569
00:29:08,280 --> 00:29:09,800
Speaker 1: the ball so that it gets to your friend, you

570
00:29:09,920 --> 00:29:11,400
Speaker 1: gotta throw it like a little bit to the left,

571
00:29:11,440 --> 00:29:13,760
Speaker 1: because if you throw a ball straight while you're spinning

572
00:29:13,760 --> 00:29:15,800
Speaker 1: on a merry go round in your view, the ball

573
00:29:15,840 --> 00:29:18,560
Speaker 1: doesn't move straight, it'll like curve to the right. So

574
00:29:18,560 --> 00:29:20,920
Speaker 1: you've gotta account for all these things when you're throwing

575
00:29:20,920 --> 00:29:23,160
Speaker 1: the ball. And so because the earth is spinning, the

576
00:29:23,240 --> 00:29:25,360
Speaker 1: same effect happens when you like drop a rock from

577
00:29:25,400 --> 00:29:27,080
Speaker 1: the top of a tower, or if you've ever been

578
00:29:27,080 --> 00:29:29,000
Speaker 1: to one of those cool science museums where they have

579
00:29:29,240 --> 00:29:31,720
Speaker 1: one of those really tall pendulum, it's called the foe

580
00:29:31,760 --> 00:29:33,480
Speaker 1: called pendulum, but you have to say with the French

581
00:29:33,520 --> 00:29:38,440
Speaker 1: accent it's called a pendulum. Focal is an experiment done

582
00:29:38,520 --> 00:29:41,120
Speaker 1: in the eighteen fifties originally that proved that the Earth

583
00:29:41,200 --> 00:29:44,600
Speaker 1: was spinning because you can feel this effect on this pendulum, right.

584
00:29:44,600 --> 00:29:47,200
Speaker 1: The pendulum is like a heavy weight on a very

585
00:29:47,280 --> 00:29:50,479
Speaker 1: long string, and so it's sensitive to small pushes in

586
00:29:50,600 --> 00:29:53,240
Speaker 1: various directions. You set the pendulum going back and forth,

587
00:29:53,280 --> 00:29:56,040
Speaker 1: and then it eventually just starts spinning on its own.

588
00:29:56,320 --> 00:29:58,840
Speaker 1: And that spinning of course, is coming from the Coriola's force.

589
00:29:58,920 --> 00:30:01,760
Speaker 1: It's coming from the in of the Earth. Right. So

590
00:30:01,920 --> 00:30:04,120
Speaker 1: I think all these things kind of add up to

591
00:30:04,160 --> 00:30:07,680
Speaker 1: that conclusion that we might feel like we're motionless here

592
00:30:07,720 --> 00:30:10,560
Speaker 1: on Earth, and that even though motionless doesn't mean anything,

593
00:30:10,600 --> 00:30:12,880
Speaker 1: we still sort of feel motionless. But really there are

594
00:30:12,920 --> 00:30:15,720
Speaker 1: these strange forces going on, right because the Earth is

595
00:30:15,760 --> 00:30:19,680
Speaker 1: spinning and the reference frames are accelerating right, m exactly.

596
00:30:19,800 --> 00:30:21,600
Speaker 1: And if the Earth was not spinning, if there was

597
00:30:21,680 --> 00:30:25,640
Speaker 1: no like acceleration, because remember, spin is acceleration, then there

598
00:30:25,680 --> 00:30:28,800
Speaker 1: be no way to measure the Earth's velocity relative to

599
00:30:28,840 --> 00:30:31,520
Speaker 1: other stuff. So we can measure the Earth's spin only

600
00:30:31,520 --> 00:30:35,120
Speaker 1: because it is acceleration. It's not just constant velocity. That's

601
00:30:35,120 --> 00:30:38,120
Speaker 1: a bit counterintuitive because it feels like it's constant because

602
00:30:38,120 --> 00:30:41,920
Speaker 1: it's a constant rate of spin. But constant spin requires

603
00:30:41,960 --> 00:30:44,840
Speaker 1: acceleration because requires a force to move you towards the

604
00:30:44,880 --> 00:30:48,640
Speaker 1: center of the spin. All right, well, what about relative

605
00:30:48,720 --> 00:30:52,840
Speaker 1: to the Sun. That's a pretty stable and almost stationary

606
00:30:52,880 --> 00:30:55,680
Speaker 1: big thing. Can we can we be motionless relative to

607
00:30:55,680 --> 00:30:58,360
Speaker 1: the Sun. Yeah, that's actually a really interesting question. And

608
00:30:58,400 --> 00:31:00,920
Speaker 1: you know, the Earth, of course is moving pretty fast

609
00:31:01,000 --> 00:31:03,520
Speaker 1: relative to the Sun, and we should be glad that

610
00:31:03,560 --> 00:31:05,680
Speaker 1: we are, because it's the reason that we don't just

611
00:31:05,800 --> 00:31:09,600
Speaker 1: like plunge headfirst into the Sun. Right. People think about like,

612
00:31:09,920 --> 00:31:11,880
Speaker 1: if you're near a black hole, would you just get

613
00:31:11,880 --> 00:31:15,080
Speaker 1: automatically sucked up, when the answer is no, if you

614
00:31:15,120 --> 00:31:17,520
Speaker 1: can get into orbit around the black hole, And the

615
00:31:17,560 --> 00:31:21,320
Speaker 1: same thing is true for orbiting around any gravitational object.

616
00:31:21,400 --> 00:31:23,520
Speaker 1: Like the reason the Earth doesn't fall into the Sun

617
00:31:23,840 --> 00:31:26,760
Speaker 1: is because we have high speed relative to the Sun.

618
00:31:26,960 --> 00:31:28,360
Speaker 1: You know, this is the kind of stuff people are

619
00:31:28,360 --> 00:31:31,680
Speaker 1: talking about with these like New Shepherd and Virgin galactic

620
00:31:31,840 --> 00:31:34,360
Speaker 1: launches into space. You know, people are saying that's really

621
00:31:34,400 --> 00:31:36,840
Speaker 1: super cool and awesome, but you know, all they did

622
00:31:36,840 --> 00:31:39,040
Speaker 1: was sort of like go up into space. The much

623
00:31:39,080 --> 00:31:41,120
Speaker 1: more difficult thing is to get up into space and

624
00:31:41,160 --> 00:31:44,360
Speaker 1: then get into orbit because that requires a super fast

625
00:31:44,480 --> 00:31:47,520
Speaker 1: velocity relative to the Earth. So the Earth is moving

626
00:31:47,560 --> 00:31:50,280
Speaker 1: relative to the Sun at like thirty kilometers per second,

627
00:31:50,600 --> 00:31:52,720
Speaker 1: and we should be glad that it is, because otherwise

628
00:31:52,760 --> 00:31:56,240
Speaker 1: we would fall headfirst into that huge burning ball of plasma.

629
00:31:57,160 --> 00:31:59,600
Speaker 1: You mean, those commercial flights that just kind of dip

630
00:31:59,600 --> 00:32:02,000
Speaker 1: into space. They don't like, staying in space is a

631
00:32:02,040 --> 00:32:05,000
Speaker 1: lot harder. Yeah, staying in space is a lot harder

632
00:32:05,000 --> 00:32:07,200
Speaker 1: than dipping your toes and then coming back to Earth.

633
00:32:07,480 --> 00:32:09,440
Speaker 1: Like they were just up in space for a few

634
00:32:09,440 --> 00:32:11,800
Speaker 1: minutes and they just came right back. But you know,

635
00:32:11,840 --> 00:32:14,360
Speaker 1: what NASA has done, and even SpaceX is done, is

636
00:32:14,480 --> 00:32:17,000
Speaker 1: much more difficult because you need a much higher velocity

637
00:32:17,080 --> 00:32:20,160
Speaker 1: to stay in space. Right, Staying in space basically means

638
00:32:20,200 --> 00:32:22,640
Speaker 1: falling towards the Earth and missing it, sort of like

639
00:32:22,720 --> 00:32:25,160
Speaker 1: in the Hitchhiker's Guide to the Galaxy. And to do that,

640
00:32:25,200 --> 00:32:27,360
Speaker 1: you need to be moving fast enough that when you

641
00:32:27,400 --> 00:32:30,080
Speaker 1: fall towards the Earth, it's sort of not there anymore,

642
00:32:30,240 --> 00:32:32,440
Speaker 1: just like the motion on the Merry Go Round. Yeah

643
00:32:32,440 --> 00:32:35,200
Speaker 1: you like overshoot it? Yeah, exactly, overshoot it. And so

644
00:32:35,240 --> 00:32:36,880
Speaker 1: that's what the Earth is doing around the Sun. We're

645
00:32:36,880 --> 00:32:40,479
Speaker 1: moving at thirty kilometers per second, which is pretty fast,

646
00:32:40,800 --> 00:32:43,320
Speaker 1: but that's the velocity we need because the Sun's gravity

647
00:32:43,320 --> 00:32:46,320
Speaker 1: is so strong. That's the velocity we need to overshoot

648
00:32:46,360 --> 00:32:49,280
Speaker 1: it every time we fall in towards it. Wow, Well,

649
00:32:49,280 --> 00:32:53,680
Speaker 1: what about relative to the galaxy? Um? Can we how

650
00:32:53,720 --> 00:32:55,920
Speaker 1: fast is the Sun moving relative to the galaxy? The

651
00:32:55,960 --> 00:32:58,960
Speaker 1: Sun is really zipping around right here, we're talking about

652
00:32:58,960 --> 00:33:02,680
Speaker 1: gravitational system. And at the core of the galaxy is

653
00:33:02,720 --> 00:33:05,560
Speaker 1: an enormous mass of stuff. Right. We are sort of

654
00:33:05,600 --> 00:33:08,800
Speaker 1: like out in the suburbs, where there's like one star

655
00:33:09,000 --> 00:33:12,000
Speaker 1: every few cubic light years, But in the center of

656
00:33:12,040 --> 00:33:15,280
Speaker 1: the galaxy, things are much dense or much crazier, right,

657
00:33:15,280 --> 00:33:18,440
Speaker 1: and they're hot, throbbing urban center. There's an enormous black

658
00:33:18,480 --> 00:33:21,640
Speaker 1: hole with millions and millions of stars worth of mass

659
00:33:21,880 --> 00:33:24,000
Speaker 1: and then just lots of stars, and so there's an

660
00:33:24,040 --> 00:33:28,440
Speaker 1: extraordinarily strong gravitational force on the Sun from the center

661
00:33:28,480 --> 00:33:31,200
Speaker 1: of the galaxy, and so the Sun is orbiting the

662
00:33:31,240 --> 00:33:33,960
Speaker 1: center of the galaxy. But to avoid falling into that

663
00:33:34,000 --> 00:33:37,120
Speaker 1: black hole, it has to move really fast. It moves

664
00:33:37,120 --> 00:33:40,840
Speaker 1: at eight hundred thousand kilometers per hour relative to the

665
00:33:40,840 --> 00:33:43,600
Speaker 1: center of the galaxy. Wow, that's crazy. Like if you

666
00:33:43,600 --> 00:33:45,320
Speaker 1: plant the flag in the middle of the galaxy, that's

667
00:33:45,320 --> 00:33:48,000
Speaker 1: how fast we're moving relative to that. Yeah, relative to

668
00:33:48,000 --> 00:33:50,920
Speaker 1: that black hole, we are moving at eight hundred thousand

669
00:33:51,000 --> 00:33:53,480
Speaker 1: kilometers per hour. It's pretty impressive. But you know, the

670
00:33:53,520 --> 00:33:56,840
Speaker 1: galaxy is so big that it still takes like two

671
00:33:56,920 --> 00:33:59,920
Speaker 1: hundred million years for the Sun to go around the

672
00:34:00,040 --> 00:34:03,080
Speaker 1: center of the galaxy, Like a galactic year is two

673
00:34:03,600 --> 00:34:07,440
Speaker 1: million earth years. Wow, that's a long time to wait

674
00:34:07,480 --> 00:34:11,399
Speaker 1: for your birthday every time. But I think the point

675
00:34:11,440 --> 00:34:13,839
Speaker 1: is that, you know, you might think that you're motionless here,

676
00:34:13,840 --> 00:34:16,520
Speaker 1: but actually you're moving relative to the Sun of the Earth.

677
00:34:16,600 --> 00:34:19,000
Speaker 1: And actually you might think that the Earth is not moving,

678
00:34:19,040 --> 00:34:21,000
Speaker 1: but then it's moving relative to the Sun, and the

679
00:34:21,000 --> 00:34:25,560
Speaker 1: Sun is moving relative to the galaxy by a lot um.

680
00:34:25,600 --> 00:34:27,920
Speaker 1: But then I guess the question is is the galaxy

681
00:34:27,960 --> 00:34:30,359
Speaker 1: moving relative to anything else? Right? I think this sort

682
00:34:30,360 --> 00:34:32,560
Speaker 1: of goes back to the heart of the original question,

683
00:34:32,560 --> 00:34:34,600
Speaker 1: which is like can you be motionless in space? Can

684
00:34:34,640 --> 00:34:37,040
Speaker 1: you like get away from all of this stuff? Or

685
00:34:37,120 --> 00:34:39,799
Speaker 1: like the other question is like the galaxy itself can

686
00:34:39,880 --> 00:34:42,520
Speaker 1: it just be hanging out in space? So this is

687
00:34:42,520 --> 00:34:44,760
Speaker 1: a really interesting question. But again you have to measure

688
00:34:44,760 --> 00:34:48,239
Speaker 1: the motion of the galaxy relative to other stuff. And

689
00:34:48,280 --> 00:34:50,719
Speaker 1: so now what's the other stuff when you can look

690
00:34:50,760 --> 00:34:54,240
Speaker 1: at other nearby galaxies and measure like our velocity relative

691
00:34:54,280 --> 00:34:58,040
Speaker 1: to Andromeda or relative to other galaxies that are nearby,

692
00:34:58,080 --> 00:35:00,279
Speaker 1: but that's just sort of seems arbitrary. Is just you know,

693
00:35:00,320 --> 00:35:03,160
Speaker 1: a random galaxy nearby? What you can do, though, which

694
00:35:03,200 --> 00:35:05,680
Speaker 1: I think is pretty cool, is you can find the

695
00:35:05,800 --> 00:35:09,440
Speaker 1: motion of our galaxy relative to like all of the

696
00:35:09,560 --> 00:35:12,040
Speaker 1: stuff in the universe, like the average of all of

697
00:35:12,080 --> 00:35:15,839
Speaker 1: the things in the universe. Interesting I mean in terms

698
00:35:15,880 --> 00:35:18,680
Speaker 1: of mass or energy or just like to think that

699
00:35:18,719 --> 00:35:22,120
Speaker 1: it has some sort of like aggregate that's not moving exactly.

700
00:35:22,160 --> 00:35:25,000
Speaker 1: We talked earlier about how you can't measure your velocity

701
00:35:25,160 --> 00:35:28,400
Speaker 1: relative to space itself, right, but you can measure your

702
00:35:28,440 --> 00:35:31,840
Speaker 1: velocity relative to stuff. And even though there's no preferred

703
00:35:31,840 --> 00:35:35,200
Speaker 1: location in space, there is stuff in space, right, you

704
00:35:35,200 --> 00:35:37,640
Speaker 1: can ask, like, is there a velocity where you're not

705
00:35:37,719 --> 00:35:40,759
Speaker 1: moving relative to like all of the average stuff. And

706
00:35:40,800 --> 00:35:43,160
Speaker 1: so the way cosmologists do this is they look at

707
00:35:43,160 --> 00:35:46,879
Speaker 1: the cosmic microwave background radiation. This is the radiation that's

708
00:35:46,960 --> 00:35:50,040
Speaker 1: left over from the very very early universe, that plasma

709
00:35:50,120 --> 00:35:53,440
Speaker 1: that was hot and glowing. Around three eighty thousand years

710
00:35:53,480 --> 00:35:57,239
Speaker 1: after the beginning of the universe, the universe became transparent,

711
00:35:57,560 --> 00:36:00,080
Speaker 1: and that light has been bouncing around ever since. In

712
00:36:00,400 --> 00:36:02,360
Speaker 1: so that light sort of tells us about where the

713
00:36:02,400 --> 00:36:05,120
Speaker 1: stuff was in the very early universe, and we can

714
00:36:05,200 --> 00:36:08,799
Speaker 1: measure our velocity relative to this radiation which is sort

715
00:36:08,800 --> 00:36:12,319
Speaker 1: of like measuring your velocity relative to the stuff in

716
00:36:12,400 --> 00:36:15,200
Speaker 1: the early universe. So while you can't measure your velocity

717
00:36:15,239 --> 00:36:18,120
Speaker 1: relative to like empty space, space is not empty. It's

718
00:36:18,160 --> 00:36:21,560
Speaker 1: filled with stuff, and you can actually find a preferred

719
00:36:21,600 --> 00:36:25,920
Speaker 1: reference frame in which the cosmic microwave background radiation or

720
00:36:25,920 --> 00:36:29,480
Speaker 1: the plasma that generated it is at rest. WHOA, I

721
00:36:29,480 --> 00:36:31,120
Speaker 1: feel like you just kind of pulled a fast one

722
00:36:31,160 --> 00:36:33,400
Speaker 1: on me, Like at first, you can convince me at

723
00:36:33,440 --> 00:36:36,200
Speaker 1: first that there's no way to have an absolutely velocity,

724
00:36:36,239 --> 00:36:37,839
Speaker 1: But now and you're sort of telling me that there

725
00:36:37,920 --> 00:36:39,560
Speaker 1: is kind of a way to do it if you

726
00:36:40,120 --> 00:36:44,640
Speaker 1: depending on how you define what the universe is right exactly,

727
00:36:44,719 --> 00:36:47,719
Speaker 1: imagine an empty universe. You can't have any velocity in

728
00:36:47,719 --> 00:36:51,040
Speaker 1: that empty universe. Now put ten galaxies in that universe.

729
00:36:51,239 --> 00:36:53,520
Speaker 1: You can say, well, I could have a velocity relative

730
00:36:53,560 --> 00:36:56,240
Speaker 1: to one galaxy or another one, or I could just say,

731
00:36:56,280 --> 00:36:59,560
Speaker 1: what's my velocity relative to all the stuff, Like find

732
00:36:59,600 --> 00:37:02,200
Speaker 1: the ridge motion of all the stuff in the universe,

733
00:37:02,320 --> 00:37:04,719
Speaker 1: and you could say that's my velocity, and it's a

734
00:37:04,760 --> 00:37:08,279
Speaker 1: reasonable definition. It's sort of arbitrary, but it's also sort

735
00:37:08,280 --> 00:37:10,799
Speaker 1: of not arbitrary because like there's only one way to

736
00:37:10,920 --> 00:37:14,960
Speaker 1: choose the average velocity of all the stuff in the universe, right,

737
00:37:15,000 --> 00:37:17,040
Speaker 1: because that is the universe, right, Like, who cares? So

738
00:37:17,120 --> 00:37:21,759
Speaker 1: that space is slippery and undefinable, and you can't, you know,

739
00:37:22,040 --> 00:37:24,480
Speaker 1: measure a relative to it. What matters is this stuff

740
00:37:24,480 --> 00:37:26,320
Speaker 1: in it? Maybe? I guess that you know, it depends

741
00:37:26,320 --> 00:37:29,160
Speaker 1: philosophically if you think space is fundamental or mass is

742
00:37:29,200 --> 00:37:31,360
Speaker 1: fundamental or whatever. I mean. You could also define a

743
00:37:31,400 --> 00:37:34,279
Speaker 1: frame in which those ten galaxies, your whole universe in

744
00:37:34,280 --> 00:37:37,680
Speaker 1: this example, is moving right at a billion miles per

745
00:37:37,719 --> 00:37:39,920
Speaker 1: hour to the left. You know, you could define that

746
00:37:39,960 --> 00:37:43,440
Speaker 1: reference frame also the universe theoretical physics says their equivalent,

747
00:37:43,480 --> 00:37:45,279
Speaker 1: But yeah, I think it makes sense to define a

748
00:37:45,320 --> 00:37:47,920
Speaker 1: reference frame relative to all the stuff in the universe.

749
00:37:47,960 --> 00:37:50,120
Speaker 1: And the crazy thing is we can kind of do that.

750
00:37:50,239 --> 00:37:52,200
Speaker 1: And we can do that by looking at the cosmic

751
00:37:52,200 --> 00:37:55,279
Speaker 1: microwave background radiation and asking are we moving through that

752
00:37:55,400 --> 00:37:58,520
Speaker 1: radiation at some speed in some direction? All right, well,

753
00:37:58,600 --> 00:38:00,920
Speaker 1: let's get into how we can actually to hell that

754
00:38:01,160 --> 00:38:04,920
Speaker 1: velocity relative to the background radiation, and maybe there are

755
00:38:04,960 --> 00:38:07,600
Speaker 1: other ways to be motionless in the universe. But first

756
00:38:07,680 --> 00:38:21,920
Speaker 1: let's take another quick break all right, So it is

757
00:38:22,000 --> 00:38:27,320
Speaker 1: sort of possible to define motion relative to all the

758
00:38:27,360 --> 00:38:29,480
Speaker 1: stuff in the universe, not to space, but to all

759
00:38:29,480 --> 00:38:32,120
Speaker 1: the stuff in the universe. You're saying you can do

760
00:38:32,120 --> 00:38:35,840
Speaker 1: that through the cosmic microwave background radiation. Now that's the

761
00:38:36,120 --> 00:38:38,520
Speaker 1: like the leftover light from the Big Bang. Are you

762
00:38:38,560 --> 00:38:40,800
Speaker 1: saying that we can tell which way we're moving relative

763
00:38:40,880 --> 00:38:44,000
Speaker 1: to that kind of glow? We can, absolutely, because like

764
00:38:44,080 --> 00:38:47,040
Speaker 1: everything else, we can measure our velocity relative to the

765
00:38:47,080 --> 00:38:50,760
Speaker 1: stuff that emitted it by using red shifts and blue shifts.

766
00:38:51,160 --> 00:38:53,839
Speaker 1: Like if a star is moving away from us, then

767
00:38:53,880 --> 00:38:56,839
Speaker 1: the light that it sends us is red shifted. It's

768
00:38:56,880 --> 00:39:00,439
Speaker 1: wavelength is lengthen it's stretched out because that's is moving

769
00:39:00,440 --> 00:39:02,799
Speaker 1: away from us. And if it starts moving towards us,

770
00:39:02,880 --> 00:39:06,359
Speaker 1: then its wavelength is shrunk. It's like squeezed down. It's

771
00:39:06,440 --> 00:39:09,960
Speaker 1: blue shifted. And when we measure the cosmic bacrowave background radiation,

772
00:39:10,040 --> 00:39:13,360
Speaker 1: we notice a very very strong effect that one side

773
00:39:13,360 --> 00:39:15,279
Speaker 1: of the sky is red shifted and the other side

774
00:39:15,320 --> 00:39:17,840
Speaker 1: of the sky is blue shifted. So that very clearly

775
00:39:17,880 --> 00:39:20,759
Speaker 1: gives you a measurement for like our motion through the

776
00:39:20,840 --> 00:39:24,680
Speaker 1: cosmic microwave background radiation. M M. Interesting. It's sort of

777
00:39:24,719 --> 00:39:26,319
Speaker 1: like if you stick your head out this side of

778
00:39:26,320 --> 00:39:28,600
Speaker 1: a moving car. You know, one side of your head

779
00:39:28,640 --> 00:39:32,200
Speaker 1: would feel the air hitting one side of your face

780
00:39:32,480 --> 00:39:34,440
Speaker 1: harder than it would on the other side, and then

781
00:39:34,480 --> 00:39:36,240
Speaker 1: that's how you know that you're moving in a particular

782
00:39:36,280 --> 00:39:38,880
Speaker 1: direction relative to the air you're moving in. Yeah, exactly.

783
00:39:38,920 --> 00:39:41,200
Speaker 1: It's like if you said, well, let's fill the whole

784
00:39:41,320 --> 00:39:43,799
Speaker 1: universe with air, then all of a sudden, there is

785
00:39:43,840 --> 00:39:46,720
Speaker 1: any reference frame that makes sense, like your air speed

786
00:39:46,880 --> 00:39:49,839
Speaker 1: through this universe, right, and it kind of is sort

787
00:39:49,880 --> 00:39:52,480
Speaker 1: of filled with air. I mean, it's not actually air molecules,

788
00:39:52,480 --> 00:39:55,719
Speaker 1: of course, but it's radiation from the early universe, and

789
00:39:55,840 --> 00:39:57,960
Speaker 1: we can measure our speed relative to it, like the

790
00:39:58,000 --> 00:40:02,279
Speaker 1: speed of the cosmic microwave back under radiation wind m m.

791
00:40:03,040 --> 00:40:05,480
Speaker 1: So like if we look in one direction, this micro

792
00:40:05,640 --> 00:40:08,080
Speaker 1: background radiation looks a little bluer, and then we looked

793
00:40:08,120 --> 00:40:10,359
Speaker 1: on the other side, it looks a little redder, and

794
00:40:10,440 --> 00:40:13,799
Speaker 1: that doesn't change I guess, right, it's it's sort of

795
00:40:13,840 --> 00:40:16,920
Speaker 1: relative to what frame of motion. I guess you can

796
00:40:16,960 --> 00:40:19,840
Speaker 1: measure relative to our galaxy, right, Yeah, our galaxy is

797
00:40:19,920 --> 00:40:23,000
Speaker 1: moving through this now Earth of course, is moving around

798
00:40:23,040 --> 00:40:25,440
Speaker 1: the Sun, which is moving around the center of the galaxy,

799
00:40:25,520 --> 00:40:27,920
Speaker 1: so you have to subtract that out. But we measure

800
00:40:27,960 --> 00:40:31,200
Speaker 1: this as the motion of our galaxy through the c MB,

801
00:40:31,680 --> 00:40:34,520
Speaker 1: and it's pretty cool. And it's also not that small,

802
00:40:34,560 --> 00:40:37,120
Speaker 1: like we're kind of clipping along through the c NB

803
00:40:37,280 --> 00:40:39,520
Speaker 1: at a pretty healthy rate. Yeah, it's like millions of

804
00:40:39,560 --> 00:40:43,879
Speaker 1: kilometers per hour. Yeah, exactly two point one million kilometers

805
00:40:43,920 --> 00:40:46,200
Speaker 1: per hour through the c MB. And for those of

806
00:40:46,239 --> 00:40:48,359
Speaker 1: you who are enthusiasts about the c MP, you might

807
00:40:48,400 --> 00:40:50,719
Speaker 1: know that we talk a lot about the details of

808
00:40:50,719 --> 00:40:52,640
Speaker 1: the scene, being like the wiggles in it, how it's

809
00:40:52,640 --> 00:40:54,960
Speaker 1: a little hotter here and a little colder there, and

810
00:40:55,000 --> 00:40:57,880
Speaker 1: that corresponds to fascinating information about the nature of the

811
00:40:57,880 --> 00:41:01,240
Speaker 1: early universe. That's after we sup tracked out this big

812
00:41:01,320 --> 00:41:03,799
Speaker 1: red shift and blue shift effect. We sort of like

813
00:41:03,960 --> 00:41:06,560
Speaker 1: neutralize that so we can just look at the relative

814
00:41:06,640 --> 00:41:10,400
Speaker 1: variations here, we're talking about a velocity relative to the CNB.

815
00:41:10,680 --> 00:41:12,759
Speaker 1: We subtract that out and then we look for these

816
00:41:12,760 --> 00:41:15,919
Speaker 1: wiggles to extract all sorts of cool physics juice about

817
00:41:15,920 --> 00:41:18,960
Speaker 1: the universe, and it has a lot of items c

818
00:41:19,200 --> 00:41:23,000
Speaker 1: I imagine for Cosmos. It's probably toxic. You know, everything

819
00:41:23,040 --> 00:41:25,640
Speaker 1: out there in space will kill you. I'll give you

820
00:41:25,640 --> 00:41:28,279
Speaker 1: a good sumber. You just made me think that. You know,

821
00:41:28,360 --> 00:41:30,960
Speaker 1: the CMB comes from the Big Bang, which is the

822
00:41:31,000 --> 00:41:34,840
Speaker 1: beginning of the universe. Right, So if there was a

823
00:41:34,960 --> 00:41:39,440
Speaker 1: relative velocity between the CNB, which represents the stuff in

824
00:41:39,520 --> 00:41:43,360
Speaker 1: the universe, and actual space, then it would have to

825
00:41:43,400 --> 00:41:45,719
Speaker 1: come from the Big Bang, right, Like it would mean

826
00:41:45,719 --> 00:41:48,120
Speaker 1: that the Big Bang was sort of moving relative to

827
00:41:48,160 --> 00:41:51,080
Speaker 1: space when it happened. But that's arbitrary, right. The motion

828
00:41:51,160 --> 00:41:54,640
Speaker 1: of the CNB relative to space depends on defining a

829
00:41:54,719 --> 00:41:58,200
Speaker 1: reference frame for space, which doesn't exist. So you can

830
00:41:58,239 --> 00:42:01,360
Speaker 1: imagine the CNB as stay scenary in space, or you

831
00:42:01,360 --> 00:42:03,400
Speaker 1: can imagine the CNB and the Big Bang is like

832
00:42:03,520 --> 00:42:06,040
Speaker 1: moving through space at a zillion miles per hour. They're

833
00:42:06,080 --> 00:42:08,840
Speaker 1: totally equivalent, and you can't tell the difference because you

834
00:42:08,920 --> 00:42:11,399
Speaker 1: can't define a reference frame for space. Right. But it's

835
00:42:11,440 --> 00:42:13,200
Speaker 1: kind of weird to think that the Big Bang happened

836
00:42:13,239 --> 00:42:16,040
Speaker 1: at a zillion miles per hour. Yeah, it is weird,

837
00:42:16,080 --> 00:42:18,799
Speaker 1: and it is more natural to define a reference frame

838
00:42:18,840 --> 00:42:20,959
Speaker 1: for like the stuff. And it's also kind of cool

839
00:42:21,000 --> 00:42:22,880
Speaker 1: because it feels like a choice was made. Right. It

840
00:42:22,920 --> 00:42:25,920
Speaker 1: feels like, well, the stuff is here and it's not

841
00:42:26,160 --> 00:42:28,560
Speaker 1: over there, and it's not moving at this speed. But

842
00:42:28,640 --> 00:42:32,080
Speaker 1: really it's all relative, right. It feels unnatural to imagine

843
00:42:32,080 --> 00:42:33,960
Speaker 1: the stuff moving in a million miles per hour. It

844
00:42:33,960 --> 00:42:36,919
Speaker 1: feels more natural to say, let's choose a reference frame

845
00:42:36,920 --> 00:42:40,160
Speaker 1: with the stuff is zero. But that's sort of our intuition.

846
00:42:40,200 --> 00:42:44,320
Speaker 1: It's not like physically meaningful. But so I guess then,

847
00:42:44,520 --> 00:42:46,520
Speaker 1: you know, if we are moving relative to the CNB,

848
00:42:46,800 --> 00:42:49,040
Speaker 1: do you know which way we're going, Like, are we

849
00:42:49,200 --> 00:42:51,920
Speaker 1: moving up? Like relative to California? Are we moving up

850
00:42:51,960 --> 00:42:54,520
Speaker 1: down that? Right? Relative to the universe? Like can you

851
00:42:54,520 --> 00:42:56,920
Speaker 1: compute that? We can compute that, and there is a vector.

852
00:42:57,280 --> 00:42:59,080
Speaker 1: It doesn't make sense to talk about it relative to

853
00:42:59,080 --> 00:43:02,520
Speaker 1: California because California is directed through the CMB changes all

854
00:43:02,520 --> 00:43:04,319
Speaker 1: the time, because you know, the Earth is spinning and

855
00:43:04,360 --> 00:43:06,279
Speaker 1: the Earth is moving around the Sun, and yeah, it's

856
00:43:06,280 --> 00:43:08,960
Speaker 1: always moving. But at any given time you could compete like, oh,

857
00:43:09,080 --> 00:43:11,759
Speaker 1: right now we are technically moving through the stuff in

858
00:43:11,800 --> 00:43:14,520
Speaker 1: the universe in this direction. Yeah, yeah, you can do

859
00:43:14,560 --> 00:43:16,800
Speaker 1: that calculation. In fact, maybe we should make a website

860
00:43:16,800 --> 00:43:18,239
Speaker 1: for that. That would be pretty fun for people to

861
00:43:18,239 --> 00:43:20,879
Speaker 1: see where we're moving through the universe and half past

862
00:43:20,920 --> 00:43:23,880
Speaker 1: we're going at any particular time. Yeah, Now, is it

863
00:43:23,920 --> 00:43:27,040
Speaker 1: possible then to be sort of motionless relative to the CNB,

864
00:43:27,239 --> 00:43:29,759
Speaker 1: Like are there spots in the universe or could we

865
00:43:29,960 --> 00:43:32,200
Speaker 1: you know, as we're moving and spinning and moving through

866
00:43:32,200 --> 00:43:34,600
Speaker 1: the galaxy and the Solar System, could we at some

867
00:43:34,960 --> 00:43:37,919
Speaker 1: for an instant be not moving relative to the CMB. Yeah,

868
00:43:37,920 --> 00:43:41,560
Speaker 1: that is totally possible. And astronomers and astrophysicists called this

869
00:43:41,600 --> 00:43:45,160
Speaker 1: peculiar velocity because you know, like on average all the

870
00:43:45,200 --> 00:43:48,200
Speaker 1: stuff is stationary relative to the CNB, but you know,

871
00:43:48,320 --> 00:43:51,120
Speaker 1: nothing is stationary. Everything is like switching around and moving

872
00:43:51,160 --> 00:43:53,879
Speaker 1: relative to each other, like our galaxy and the next

873
00:43:54,040 --> 00:43:57,840
Speaker 1: galaxy over Andromeda are moving towards each other, for example.

874
00:43:58,080 --> 00:44:00,279
Speaker 1: But it is possible we just don't have and to

875
00:44:00,320 --> 00:44:03,319
Speaker 1: be stationary relative to the CNB. But you could like

876
00:44:03,600 --> 00:44:07,440
Speaker 1: get in a spaceship fly out between galaxies, measure your

877
00:44:07,480 --> 00:44:11,040
Speaker 1: velocity relative to the CNB and like perfectly adjusted so

878
00:44:11,080 --> 00:44:13,360
Speaker 1: that you're not moving. So it is sort of technically

879
00:44:13,440 --> 00:44:16,799
Speaker 1: possible to be motionless relative to the the stuff in

880
00:44:16,840 --> 00:44:19,400
Speaker 1: the universe, Yes, but not to space. But to the

881
00:44:19,400 --> 00:44:21,800
Speaker 1: stuff that the in the in the universe. You could

882
00:44:22,239 --> 00:44:24,200
Speaker 1: you know, fly out there and go too point one

883
00:44:24,200 --> 00:44:27,040
Speaker 1: million kilometers per hour in the right direction, and you

884
00:44:27,120 --> 00:44:30,920
Speaker 1: might achieve velocity that makes you still relative to the

885
00:44:31,120 --> 00:44:35,120
Speaker 1: entire universe. Yeah, exactly, you would have no average velocity

886
00:44:35,200 --> 00:44:38,360
Speaker 1: relative to all the stuff in the universe. You know,

887
00:44:38,400 --> 00:44:41,560
Speaker 1: that wouldn't change like special relativity effects because those things

888
00:44:41,600 --> 00:44:45,200
Speaker 1: are still relative to other observers and stuff like that.

889
00:44:45,440 --> 00:44:48,480
Speaker 1: But yeah, you could be motionless relative to the stuff

890
00:44:48,520 --> 00:44:52,279
Speaker 1: in the universe. That's pretty cool to think that there

891
00:44:52,440 --> 00:44:55,640
Speaker 1: is it is possible to achieve that, And I wonder

892
00:44:55,680 --> 00:44:58,279
Speaker 1: if we sort of sometimes sort of achieve it, right

893
00:44:58,680 --> 00:45:00,840
Speaker 1: like as we're spinning around the Earth and as the

894
00:45:00,880 --> 00:45:03,120
Speaker 1: Earth is spinning around the Sun, or do you think

895
00:45:03,120 --> 00:45:05,719
Speaker 1: that because the galaxy is moving so fast that there's

896
00:45:05,760 --> 00:45:08,319
Speaker 1: no way we can sort of cancel out that motion. Yeah,

897
00:45:08,320 --> 00:45:11,560
Speaker 1: our motion relative to the CMB as the galaxy is

898
00:45:11,719 --> 00:45:15,680
Speaker 1: much greater than even the Sun's motion through the galaxy. Right, Like,

899
00:45:15,719 --> 00:45:18,960
Speaker 1: the galaxy is moving at two point one million kilometers

900
00:45:18,960 --> 00:45:21,320
Speaker 1: per hour through the CMB. The Sun is moving in

901
00:45:21,400 --> 00:45:24,319
Speaker 1: eight hundred thousand kilometers per hour. So even if the

902
00:45:24,320 --> 00:45:27,000
Speaker 1: Sun was moving in just the right direction, Like opposing

903
00:45:27,280 --> 00:45:30,000
Speaker 1: the galaxy's motion to the CMB, it would still only

904
00:45:30,040 --> 00:45:32,919
Speaker 1: reduce it down to like, you know, one point three

905
00:45:33,280 --> 00:45:36,080
Speaker 1: million kilometers per hour, or it can make it even

906
00:45:36,080 --> 00:45:38,880
Speaker 1: faster up to like, you know, almost three million kilometers

907
00:45:38,960 --> 00:45:41,680
Speaker 1: per hour. But we don't ever actually achieve zero velocity

908
00:45:41,719 --> 00:45:44,560
Speaker 1: relative to the c MB. Interesting, but it is possible,

909
00:45:44,600 --> 00:45:47,960
Speaker 1: which I think is pretty cool. But there is one

910
00:45:48,080 --> 00:45:50,600
Speaker 1: last sort of confounding factor, which is the fact that

911
00:45:50,680 --> 00:45:53,839
Speaker 1: space is expanding. Now, how does that affect this possibility

912
00:45:53,840 --> 00:45:57,840
Speaker 1: of being motionless relative to the universe. Yeah, it confuses everything,

913
00:45:58,080 --> 00:46:00,839
Speaker 1: you know, because we're not just talking about objects being

914
00:46:00,880 --> 00:46:04,439
Speaker 1: static in space. Right. Space is expanding, which means new

915
00:46:04,520 --> 00:46:07,560
Speaker 1: space is being made between things. Right, so you have

916
00:46:07,680 --> 00:46:10,120
Speaker 1: a bunch of different things happening at once. You have

917
00:46:10,239 --> 00:46:13,279
Speaker 1: like the universe expanding, so that even if nothing was

918
00:46:13,320 --> 00:46:17,000
Speaker 1: moving relative to any of the other stuff, still distances

919
00:46:17,040 --> 00:46:20,920
Speaker 1: between things would be growing because space is being created

920
00:46:20,960 --> 00:46:24,120
Speaker 1: between us and other galaxies, which is like whole mind

921
00:46:24,200 --> 00:46:27,080
Speaker 1: bending concept of its own right. But then we're also

922
00:46:27,160 --> 00:46:29,960
Speaker 1: interested in that motion, like are we moving relative to

923
00:46:30,000 --> 00:46:34,120
Speaker 1: Andromeda whereas our galaxy going So cosmologists separate this out

924
00:46:34,160 --> 00:46:35,960
Speaker 1: and the two pieces as they are. Right, there's the

925
00:46:36,000 --> 00:46:39,040
Speaker 1: expansion of the whole universe, which is like happens that

926
00:46:39,120 --> 00:46:41,960
Speaker 1: in the same level, the same way everywhere between us

927
00:46:42,000 --> 00:46:44,560
Speaker 1: and other galaxies, between me and you, between the Earth

928
00:46:44,560 --> 00:46:47,040
Speaker 1: and the Sun, all this stuff. And then there's this

929
00:46:47,080 --> 00:46:51,000
Speaker 1: sort of local motion, like we call this peculiar velocity

930
00:46:51,239 --> 00:46:55,480
Speaker 1: relative to that expansion, and so astronomers define these things

931
00:46:55,520 --> 00:46:59,120
Speaker 1: called co moving coordinates, where we basically subtract out the

932
00:46:59,160 --> 00:47:01,920
Speaker 1: expansion of the universe and say, let's just isolate the

933
00:47:01,920 --> 00:47:04,759
Speaker 1: peculiar velocity, the stuff that's like only due to like

934
00:47:04,880 --> 00:47:08,719
Speaker 1: local gravity. I guess I'm not sure probably what that means.

935
00:47:08,760 --> 00:47:10,799
Speaker 1: Does that mean that it is not possible to find

936
00:47:10,800 --> 00:47:13,480
Speaker 1: that spot where you're not moving relative to the universe

937
00:47:13,520 --> 00:47:16,520
Speaker 1: because the universe is also expanding, so things will be

938
00:47:16,520 --> 00:47:18,600
Speaker 1: sort of moving relative to you even if you find

939
00:47:18,600 --> 00:47:21,040
Speaker 1: that spot. No, I think it still makes sense. I mean,

940
00:47:21,080 --> 00:47:24,399
Speaker 1: find that spot where you're not moving relative to the CMB. Now,

941
00:47:24,440 --> 00:47:27,200
Speaker 1: everything is expanding away from you, but that's true wherever

942
00:47:27,280 --> 00:47:31,240
Speaker 1: you are, so that doesn't change your average velocity relative

943
00:47:31,320 --> 00:47:34,160
Speaker 1: to the CMB because things are moving away from you.

944
00:47:34,320 --> 00:47:37,759
Speaker 1: Always in every direction, so the average velocity still would

945
00:47:37,760 --> 00:47:41,200
Speaker 1: be zero. It does mean that everything is moving away

946
00:47:41,200 --> 00:47:44,200
Speaker 1: from you always, and so nothing is really ever at rest.

947
00:47:44,400 --> 00:47:47,440
Speaker 1: But you can still have average velocity of zero relative

948
00:47:47,480 --> 00:47:49,680
Speaker 1: to all the stuff in the universe, even though that

949
00:47:49,800 --> 00:47:52,920
Speaker 1: stuff is expanding. Like imagine you're standing on the surface

950
00:47:52,960 --> 00:47:55,759
Speaker 1: of a sphere and you find a spot where you're

951
00:47:55,800 --> 00:47:58,279
Speaker 1: not moving relative to like all the average stuff in

952
00:47:58,320 --> 00:48:01,080
Speaker 1: the universe. Now that spheres exp banding, so everything is

953
00:48:01,120 --> 00:48:03,440
Speaker 1: getting bigger, but you're sort of still at the center

954
00:48:03,800 --> 00:48:07,000
Speaker 1: of all those velocities, right. I see, like the universe

955
00:48:07,000 --> 00:48:10,200
Speaker 1: could be getting bigger, but you'd still be still relative

956
00:48:10,280 --> 00:48:12,799
Speaker 1: to all of it. Yes, even though it's growing. Yes,

957
00:48:12,840 --> 00:48:14,640
Speaker 1: as long as you're defining your reference for him to

958
00:48:14,640 --> 00:48:16,799
Speaker 1: be like the average motion of all the stuff in

959
00:48:16,800 --> 00:48:19,680
Speaker 1: the universe, right, and as long as the universe is

960
00:48:19,680 --> 00:48:22,399
Speaker 1: not finite, because if it is finite, then you kind

961
00:48:22,400 --> 00:48:24,200
Speaker 1: of have to find the center of mass, or you

962
00:48:24,200 --> 00:48:26,600
Speaker 1: have to kind of find the sweet spot center in

963
00:48:26,680 --> 00:48:30,600
Speaker 1: order for really to be motionless. All right, Well, there

964
00:48:30,719 --> 00:48:34,400
Speaker 1: is another interesting scenario, which is this idea that you

965
00:48:34,440 --> 00:48:37,920
Speaker 1: can move through time or not move through time. I'm

966
00:48:37,960 --> 00:48:40,480
Speaker 1: not sure, so Daniel, How does time fit into this

967
00:48:40,520 --> 00:48:42,680
Speaker 1: idea of being motionless in space? Yeah, I think a

968
00:48:42,719 --> 00:48:45,000
Speaker 1: lot of people think about our motion through space when

969
00:48:45,040 --> 00:48:48,360
Speaker 1: they read time chapel novels, because sometimes you have, like

970
00:48:48,400 --> 00:48:51,239
Speaker 1: your protagonists creates a time travel device and they go

971
00:48:51,280 --> 00:48:53,799
Speaker 1: back in time, and then the astute reader things, hold

972
00:48:53,800 --> 00:48:56,160
Speaker 1: on a second. If you're going back in time, aren't

973
00:48:56,200 --> 00:48:58,560
Speaker 1: you going to miss the Earth? Like the Earth is

974
00:48:58,600 --> 00:49:00,200
Speaker 1: moving around the Sun. If you go back in time

975
00:49:00,239 --> 00:49:03,239
Speaker 1: of month, you should be in deep space, right? Don't

976
00:49:03,239 --> 00:49:05,839
Speaker 1: you need to move through time and space in order

977
00:49:05,840 --> 00:49:07,680
Speaker 1: to catch up with the Earth. So a lot of

978
00:49:07,719 --> 00:49:10,640
Speaker 1: readers write into me with this quibble about the science

979
00:49:10,640 --> 00:49:13,839
Speaker 1: fiction novels they read, right, because like a million years ago,

980
00:49:14,040 --> 00:49:16,359
Speaker 1: the Earth was not in the same spot at all, right,

981
00:49:16,400 --> 00:49:19,160
Speaker 1: because the galaxy is technically moving a couple of million

982
00:49:19,200 --> 00:49:21,920
Speaker 1: miles per hour. Yeah, sort of. And it's a fair

983
00:49:21,960 --> 00:49:24,520
Speaker 1: point because things are in motion, and so you need

984
00:49:24,560 --> 00:49:27,520
Speaker 1: to move sort of through time and through space. But again,

985
00:49:27,520 --> 00:49:29,920
Speaker 1: it sort of depends on your reference frame. If your

986
00:49:29,960 --> 00:49:32,759
Speaker 1: reference frame is like the center of the Earth, then

987
00:49:32,840 --> 00:49:34,840
Speaker 1: you know, none of that motion is really relevant and

988
00:49:34,880 --> 00:49:37,920
Speaker 1: it doesn't affect like how time works or how space works.

989
00:49:38,120 --> 00:49:40,560
Speaker 1: If your reference frame is the center of the galaxy,

990
00:49:40,680 --> 00:49:42,719
Speaker 1: then it does kind of matter. And so it sort

991
00:49:42,719 --> 00:49:45,720
Speaker 1: of depends on like when you're programming your time machine,

992
00:49:46,000 --> 00:49:49,520
Speaker 1: what coordinates does it take? You know, is it taking

993
00:49:49,560 --> 00:49:51,800
Speaker 1: its coordinates relative to this center of the galaxy, in

994
00:49:51,800 --> 00:49:53,600
Speaker 1: which case you better be careful about how you type

995
00:49:53,640 --> 00:49:56,040
Speaker 1: them in, or is it taking its coordinates relative to

996
00:49:56,080 --> 00:49:58,279
Speaker 1: the Earth for example, Right, But the problem is that

997
00:49:58,320 --> 00:50:01,560
Speaker 1: the Earth is accelerating, and the UH and the galaxies

998
00:50:01,560 --> 00:50:04,400
Speaker 1: and the Solar System is accelerating, So it would probably

999
00:50:04,400 --> 00:50:07,000
Speaker 1: be really really complicated, right to sort of keep that

1000
00:50:07,080 --> 00:50:09,600
Speaker 1: same reference frame exactly, And so if you're going to

1001
00:50:09,680 --> 00:50:12,160
Speaker 1: move through time, you need to also be moving through

1002
00:50:12,200 --> 00:50:14,200
Speaker 1: space to make sure you land in the right spot.

1003
00:50:15,560 --> 00:50:18,319
Speaker 1: Some good advice for when we when I build that

1004
00:50:18,360 --> 00:50:21,359
Speaker 1: time machine, or at least good advice for science fiction

1005
00:50:21,400 --> 00:50:23,600
Speaker 1: authors when you write time travel into your novel, at

1006
00:50:23,640 --> 00:50:25,840
Speaker 1: least make sure to include this so that our listeners

1007
00:50:25,840 --> 00:50:28,200
Speaker 1: don't get annoyed. Right, right, you know, you have to

1008
00:50:28,280 --> 00:50:30,600
Speaker 1: add the caveat that it's a space time machine, not

1009
00:50:30,719 --> 00:50:34,040
Speaker 1: just a time machine, exactly, exactly, every working time travel

1010
00:50:34,040 --> 00:50:37,080
Speaker 1: machine is actually a space time travel machine. There you

1011
00:50:37,160 --> 00:50:40,200
Speaker 1: go h G. Wells got it totally wrong. We should

1012
00:50:40,200 --> 00:50:42,279
Speaker 1: have been its titles. Too bad. We can't have him

1013
00:50:42,280 --> 00:50:44,560
Speaker 1: on the podcast. If we had a time machine, we

1014
00:50:44,600 --> 00:50:46,760
Speaker 1: could have him on the podcast. Yeah, but he would

1015
00:50:46,760 --> 00:50:49,880
Speaker 1: be in a totally different prison. You're right, we'd be

1016
00:50:50,000 --> 00:50:53,480
Speaker 1: interviewing him from two million miles away. All right, Well,

1017
00:50:53,480 --> 00:50:55,920
Speaker 1: I think that answers the question pretty well. Can you

1018
00:50:55,960 --> 00:50:59,200
Speaker 1: be motionless in space? The answer is no, but you

1019
00:50:59,239 --> 00:51:02,160
Speaker 1: could be most and list relative to the stuff in

1020
00:51:02,200 --> 00:51:05,759
Speaker 1: the universe, which is pretty much the universe, right, Like

1021
00:51:05,800 --> 00:51:08,640
Speaker 1: you could You could technically be motionless relative to the

1022
00:51:08,640 --> 00:51:11,200
Speaker 1: stuff in the universe, just not relative to space. WHOA,

1023
00:51:11,280 --> 00:51:14,040
Speaker 1: you just demoted space to not be like an important

1024
00:51:14,040 --> 00:51:15,719
Speaker 1: part of the nature of the universe. That's kind of

1025
00:51:15,760 --> 00:51:18,920
Speaker 1: a big deal. I think I demoted relative to the

1026
00:51:19,000 --> 00:51:22,360
Speaker 1: question in the podcast episode, but no disrespect to space.

1027
00:51:22,960 --> 00:51:26,200
Speaker 1: I like space. I like my space. But yeah, we

1028
00:51:26,280 --> 00:51:29,799
Speaker 1: hope you enjoyed Dad. Thanks for joining us, See you

1029
00:51:29,840 --> 00:51:40,040
Speaker 1: next time. Thanks for listening, and remember that Daniel and

1030
00:51:40,120 --> 00:51:43,000
Speaker 1: Jorge explained. The Universe is a production of I Heart

1031
00:51:43,120 --> 00:51:46,279
Speaker 1: Radio or more podcast For my heart Radio, visit the

1032
00:51:46,320 --> 00:51:50,080
Speaker 1: I Heart Radio app, Apple Podcasts, or wherever you listen

1033
00:51:50,160 --> 00:51:51,320
Speaker 1: to your favorite shows,