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Does the Universe have a preferred direction? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, what's one of the hardest physics questions someone's
0:11
Speaker 1: ever asked you? Oh? Well, someone asked me once. If
0:15
Speaker 1: the Earth is round, why don't people fall off the
0:18
Speaker 1: bottom of it? That is a pretty good question. Yeah,
0:21
Speaker 1: I think we got that one on live radio ones,
0:23
Speaker 1: didn't we Yeah, we did exactly no preparation. But why
0:27
Speaker 1: is that a hard question? Well, the hard part is
0:29
Speaker 1: figuring out why that question makes sense to the person
0:32
Speaker 1: asking it. You mean, like, how does gravity even work? Yeah,
0:36
Speaker 1: you have to know like what they are misunderstanding so
0:39
Speaker 1: that you can find a path to get them some
0:41
Speaker 1: actual understanding. So what's the answer. Why don't people just
0:46
Speaker 1: you know, fall off Australia? How do you know they don't?
0:48
Speaker 1: I mean, have you been to Australia? Maybe the whole
0:50
Speaker 1: thing is a hope. You mean Australia as a hoax
0:54
Speaker 1: or gravity? So hoax which one kangaroos don't really exists.
0:58
Speaker 1: I think my lawyers would advise me not to answer
1:00
Speaker 1: any of those questions. Hi am or handmade cartoonists and
1:17
Speaker 1: the creator of PhD comics. Hi, I'm Daniel. I'm a
1:20
Speaker 1: particle physicist and a professor. You see Irvine and I
1:23
Speaker 1: have never been to Australia or New Zealand. Really, you've
1:27
Speaker 1: never been down on the never been down there, planned
1:29
Speaker 1: it many times, never actually happened. How about you, You've
1:32
Speaker 1: been Australia. I think I've seen a picture of you
1:34
Speaker 1: talking to kangaroos. Yeah. Yeah, they're very chatty if you
1:37
Speaker 1: can get them to sit still. No, it's amazing. Australia's awesome.
1:42
Speaker 1: I mean it's like going to another continent, literally, but
1:44
Speaker 1: it's it's really like going to know the world. Like
1:47
Speaker 1: all the plants are different, they're bigger, or the animals
1:49
Speaker 1: are bigger, they're different. It's pretty amazing. Definitely on my
1:52
Speaker 1: to do list. Yeah, but welcome to our podcast, Daniel
1:54
Speaker 1: and Jorge Explain the Universe, a production of I Heart
1:57
Speaker 1: Radio in which we explore all the continents of modern physics,
2:01
Speaker 1: the weird, the strange, the ones that we understand, the
2:03
Speaker 1: ones that are unfamiliar, the ones that seem weird, and
2:06
Speaker 1: the ones that might bite you in the night. We
2:08
Speaker 1: talk about all the biggest questions in the universe, from
2:11
Speaker 1: the scope of the whole shebang, how it started, where
2:14
Speaker 1: it came from, how big is it, how does it
2:16
Speaker 1: all work? Where is it going? All of these questions,
2:18
Speaker 1: we talk about them without fear, without shame, and without hesitation,
2:22
Speaker 1: and we explain all of them to you. Yeah, because
2:25
Speaker 1: physics bites is what you're saying. I think sometimes you've
2:29
Speaker 1: got an understanding or problem. They can really sting. Yeah,
2:32
Speaker 1: but it is pretty cool Australia to think about Australia
2:34
Speaker 1: because if you think about it, they sort of see
2:36
Speaker 1: a whole different side of the space then we do
2:39
Speaker 1: here in North America. Yeah, and you are used to
2:41
Speaker 1: thinking about the Solar System with the Earth on the
2:44
Speaker 1: sort of top side of it, but that's sort of
2:47
Speaker 1: North Hemisphere centric. If you're in the Southern Hemisphere, then
2:50
Speaker 1: that half of the Solar System is sort of looking
2:52
Speaker 1: out and up into the universe just as much as
2:54
Speaker 1: we are. Yeah. And we have a lot of listeners
2:56
Speaker 1: in Australia. Do you think they listen to it upside
2:59
Speaker 1: down or or sort of weird to think that they're
3:01
Speaker 1: listening to this upside down from us right now? They
3:04
Speaker 1: are exactly in Australia. You're the physicist and I'm the cartoonist.
3:08
Speaker 1: That's right. You're the funny one, and I'm not so funny.
3:12
Speaker 1: You can grow goatee in Australia and I can't. But yeah,
3:15
Speaker 1: it's a pretty interesting universe, and it's a three sixty universe.
3:18
Speaker 1: It's all around us in all directions where we look
3:20
Speaker 1: from anywhere on Earth. But it's sort of interesting to
3:23
Speaker 1: think about directions in space. It is, and for a
3:25
Speaker 1: long time humans have sort of imagined that the Earth
3:28
Speaker 1: is at the center of the cosmos, that we look
3:31
Speaker 1: at the universe in every direction, but that we are
3:33
Speaker 1: sort of in a special location. And it wasn't until
3:36
Speaker 1: about five hundred years ago with Copernicus that we started
3:40
Speaker 1: to realize whole on a second, maybe there is no
3:43
Speaker 1: special location in space. Maybe we're just at some random point,
3:47
Speaker 1: and that gives you a completely different view about the
3:50
Speaker 1: shape and the nature of the universe that we are seeing. Yeah,
3:53
Speaker 1: it was weird for humans to think that we are
3:55
Speaker 1: not the center of the universe, although I am sort
3:57
Speaker 1: of the center of my universe, or wait, actual may
3:59
Speaker 1: actually right, and my kids and my my spouse are
4:02
Speaker 1: the center of my universe. Of course, I think there's
4:04
Speaker 1: an emotional moment there also when kids grow up and
4:06
Speaker 1: realize that they are not the center of everything, that
4:08
Speaker 1: the whole universe doesn't revolve around them. That other people
4:11
Speaker 1: are people too, ye, unless your your kids are aliens,
4:14
Speaker 1: which case it might have been more interesting realization. And
4:17
Speaker 1: it's kind of hard to understand what a big mental
4:20
Speaker 1: shift that was, you know, something that we now are
4:23
Speaker 1: very comfortable understanding that we are just in a random
4:25
Speaker 1: spot in the universe. But it was a huge conceptual shift,
4:28
Speaker 1: the kind of I don't think we can even really
4:30
Speaker 1: ever understand because we weren't firmly rooted in the other
4:34
Speaker 1: idea that we are special at the center of the universe.
4:37
Speaker 1: But giving up a long held assumption about the nature
4:40
Speaker 1: of the universe. That's sort of the joy of physics,
4:42
Speaker 1: you know. That's when physics stings, when it tells you, oops,
4:46
Speaker 1: you've been thinking about things completely the wrong way. The
4:49
Speaker 1: universe is fundamentally really different from the way you imagined it.
4:53
Speaker 1: I long for that kind of cosmic realignment, when it
4:56
Speaker 1: crawls up your pants and bite seeing the behind. That's
4:59
Speaker 1: what you look forward to. Yes, But so yeah, at
5:04
Speaker 1: some point humans realized or not in a kind of
5:07
Speaker 1: special point in space, you know, and it sort of
5:09
Speaker 1: informs everything right and informs the theories sort of the
5:12
Speaker 1: equations about physics. It has to do with symmetry and
5:15
Speaker 1: all that. So there's no specific or special point. We
5:18
Speaker 1: don't even know if we're at the center of the
5:19
Speaker 1: universe or like in a corner of the universe, or
5:22
Speaker 1: we don't even know if it makes sense in an
5:24
Speaker 1: infinite universe to have a point. Right, Yeah, and the
5:26
Speaker 1: joke you made earlier is actually true. You are at
5:29
Speaker 1: the center of your observable universe. You know, we don't
5:32
Speaker 1: know how big the universe is. We can only see
5:34
Speaker 1: a portion of it, and that portion is limited by
5:37
Speaker 1: the speed of light. And so the part of the
5:39
Speaker 1: universe that you can see is the part where light
5:42
Speaker 1: has had time to get to you since the beginning
5:45
Speaker 1: of the universe. And that's actually a different if you're
5:48
Speaker 1: in our son and if you're at another sun, because
5:50
Speaker 1: you can see a different portion of the universe because
5:53
Speaker 1: light that has reached you know, Alpha Centauri may not
5:56
Speaker 1: have come yet to our sun. And that's also true
5:58
Speaker 1: for my head in your head. So technically speaking, we
6:02
Speaker 1: are the centers of our own observable universes, and so
6:06
Speaker 1: the universe doesn't seem to have any kind of preference
6:08
Speaker 1: for any particular point in space, but there's sort of
6:11
Speaker 1: a bigger question about whether it has a special direction
6:14
Speaker 1: in space that it likes. Yeah, they're connected questions where
6:17
Speaker 1: they actually are separate when it is connected to the
6:19
Speaker 1: question of are the laws of physics the same everywhere
6:22
Speaker 1: in the universe? You know, if you do an experiment here,
6:25
Speaker 1: does it matter? Would you get a different answer if
6:27
Speaker 1: you do it somewhere else, or if you do it
6:29
Speaker 1: in another star system or alien physicists measuring the same
6:32
Speaker 1: law physics. We're pretty sure that they are. But there's
6:35
Speaker 1: another question, which is does the universe have a preferred direction? Right?
6:39
Speaker 1: Like if you rotate your experiment, could you possibly get
6:42
Speaker 1: a different answer? Could you measure some like preferred direction
6:46
Speaker 1: of the universe, like is there an up or down
6:49
Speaker 1: in the universe kind of or left or right? Yeah,
6:52
Speaker 1: or like a special direction around which the universe prefers
6:55
Speaker 1: or something like an axis. All right, So to be
6:57
Speaker 1: on the podcast, we'll be asking the question does the
7:04
Speaker 1: universe have a preferred direction? Now? I assume this is
7:08
Speaker 1: there like a like a spatial direction, not like an
7:10
Speaker 1: emotional direction or acting direction, creative direction. Yeah, the universe
7:15
Speaker 1: prefers method actors. Yeah, you know, prefers a comedy as
7:19
Speaker 1: opposed to draw. What's the tone of the universe, Danue?
7:23
Speaker 1: Maybe it's all universal hooks now. And that's why this
7:28
Speaker 1: is a physics podcast and not a Hollywood industry podcast.
7:31
Speaker 1: We're not talking about the latest trends in you know,
7:34
Speaker 1: representation in Hollywood movies or anything. We are talking about
7:37
Speaker 1: directions in space. You know, if the universe had some
7:41
Speaker 1: specific direction that was different from the other ones, then
7:44
Speaker 1: in principle, you might be able to measure that. You
7:45
Speaker 1: could like design an experiment that would be sensitive to it.
7:48
Speaker 1: The way, for example, the surface of the Earth does
7:51
Speaker 1: have preferred directions or different directions. Right, there is a
7:54
Speaker 1: north on the Earth and the south on the Earth,
7:56
Speaker 1: and you can design an experiment it's called a compass,
7:59
Speaker 1: to measure it, to detect it, and to use that
8:01
Speaker 1: to navigate or like if you're an Earth, there's sort
8:03
Speaker 1: of an up and down, right, I mean it depends
8:05
Speaker 1: on where you are on Earth, but there's sort of
8:07
Speaker 1: like a towards the center of the Earth or away
8:10
Speaker 1: from the center of the Earth. Is that kind of
8:11
Speaker 1: would that also count as a direction? Absolutely? Yeah, Gravity
8:14
Speaker 1: defines a direction on the surface of the Earth. Absolutely,
8:17
Speaker 1: and as you say, it's towards the center, which is
8:20
Speaker 1: actually the answer of the question why don't people fall
8:22
Speaker 1: off Australia. I'm sure people fall in Australia, but do
8:25
Speaker 1: they fall off of Australia. I don't think they trip
8:28
Speaker 1: and then fly off into space, you know. And I
8:29
Speaker 1: think we would have seen that on YouTube if that
8:31
Speaker 1: was happening. Maybe have a rocket power, you know, parachute
8:35
Speaker 1: or something, right, And the answer is intuitive and obvious
8:37
Speaker 1: to everybody who understands the Earth is the sphere. But
8:39
Speaker 1: obviously down is towards the center of the Earth, which
8:43
Speaker 1: is why people fall down towards the center of the
8:45
Speaker 1: Earth everywhere they are on the planet. And you're right,
8:47
Speaker 1: like the direction there is relative to the center of
8:50
Speaker 1: the Earth. But that's just arbitrary, right, you could pick anything.
8:53
Speaker 1: But the question is, you know, is there a non
8:55
Speaker 1: arbitrary choice. Is there a direction which makes sense no
8:58
Speaker 1: matter where you are in the universe. Well, you just
9:01
Speaker 1: made me think that. You know, we feel gravity towards
9:03
Speaker 1: the center of the Earth, but we're also being attracted
9:06
Speaker 1: by the Sun a lot, right, So does that mean
9:08
Speaker 1: that our gravitational vector or the reck kind of gravity
9:12
Speaker 1: is sort of slight, always slightly tweaked towards the sun. Yeah. Absolutely,
9:16
Speaker 1: the gravity of everything is affecting how much you weigh,
9:19
Speaker 1: and so as the Earth rotates, your weight changes a
9:23
Speaker 1: very small amount. But you know, the amount that the
9:25
Speaker 1: Sun pulls on you versus the Earth pulls on you
9:28
Speaker 1: is very small. So at noon is when I'm lightest. Right,
9:31
Speaker 1: technically there's when I weigh less. That's right. At noon,
9:34
Speaker 1: the Sun is pulling you off of the Earth, and
9:37
Speaker 1: at midnight the Sun is helping the Earth pull you
9:39
Speaker 1: towards its center, so you gain weight at night. So
9:42
Speaker 1: this is the travel the Earth's are always at noon diet,
9:46
Speaker 1: that's right. That This is why I eat a big
9:48
Speaker 1: lunch because I can. Right, every meal is lunch, the
9:53
Speaker 1: physics diet. I avoid meals at midnight, although sometimes you
9:57
Speaker 1: can't help them. I've been t thing with you. I
10:00
Speaker 1: know you eat meals at midnight made at midnight at
10:04
Speaker 1: one am, I am. I have no preferred time for
10:08
Speaker 1: directing my meals. So I guess the question is the
10:11
Speaker 1: Earth has a preferred sort of gravitational direction. But you're saying,
10:14
Speaker 1: like does the universe have maybe not a gravitational direction,
10:18
Speaker 1: but just like you know, a different direction or some
10:22
Speaker 1: sort of different effect that changes depending on which way
10:24
Speaker 1: you're pointing in out there in space. Yeah, and really
10:27
Speaker 1: sort of the cleanest way to define this is imagine
10:30
Speaker 1: getting transported to an arbitrary location in the universe. Could
10:33
Speaker 1: you build an apparatus which could measure some location so
10:37
Speaker 1: that if you're transported to some other location and randomly rotated,
10:41
Speaker 1: you could like tell how far you've been rotated. You
10:43
Speaker 1: can measure it. And you know, like on the surface
10:45
Speaker 1: of the Earth, you can tell your direction because you
10:48
Speaker 1: could just use the magnet, but you know that doesn't
10:50
Speaker 1: work obviously off the surface of the Earth. So could
10:52
Speaker 1: you build like a universal compass that always tells you,
10:55
Speaker 1: you know, a reference direction. And if the universe has
10:58
Speaker 1: no preferred direction, then that's imp possible because there's no
11:01
Speaker 1: physical mechanism which prefers one direction over another. Right, that
11:04
Speaker 1: would help you sort of navigate the universe in a way, right,
11:07
Speaker 1: Like if you get lost in the universe, you can
11:09
Speaker 1: sort of look at your cosmological compass and be like, oh,
11:12
Speaker 1: I need to go you know, east or whatever in space,
11:15
Speaker 1: and I might reach Earth again. It certainly would help
11:18
Speaker 1: you navigate, but it would also like blow up our
11:20
Speaker 1: idea of how the universe works. Right now, we really
11:23
Speaker 1: assume that the universe has no preferred direction and no
11:26
Speaker 1: preferred rotation. But recently there have been some ideas that
11:29
Speaker 1: suggest that maybe there is a preferred direction. And these
11:33
Speaker 1: go by sort of a cosmically silly name. Yeah, because
11:36
Speaker 1: we've been assuming that if there is a special direction,
11:39
Speaker 1: it would be the universe is preferred direction. But what
11:41
Speaker 1: if there's a direction of the universe does not like like,
11:44
Speaker 1: what if it's the opposite, What if it's like a
11:47
Speaker 1: least favorite direction in the universe, a cosmological axis of evil. Yeah,
11:52
Speaker 1: that's the sort of name that you have for it
11:54
Speaker 1: in the in the in the physics community, right, the
11:57
Speaker 1: cosmological access of evil, that's right, has been this idea
12:00
Speaker 1: of bubbling up that maybe we were wrong in thinking
12:04
Speaker 1: that the universe has no preferred direction. Maybe it does
12:07
Speaker 1: or non preferred direction, right. I think the origin of
12:10
Speaker 1: the idea access of evil is that it undermines our
12:13
Speaker 1: idea that the universe doesn't prefer anything. It's like, nobody
12:16
Speaker 1: should be preferred to the access of evils like spoiling
12:18
Speaker 1: an otherwise pristine and beautiful idea. Oh, I see, but
12:22
Speaker 1: it is a phrase that people use in the physics
12:25
Speaker 1: community to like, oh, you're talking about the cosmological access
12:28
Speaker 1: of evil? Oh? Absolutely or c A for sure. Absolutely.
12:32
Speaker 1: There's a paper titled the Axis of Evil, which I
12:35
Speaker 1: just read yesterday. Like, this is not something I came
12:38
Speaker 1: up with or just a joke on podcasts. It's really
12:41
Speaker 1: a physics term for a deep concept. I feel like
12:45
Speaker 1: you just use I read it in a paper as
12:47
Speaker 1: in like that's supposed to be an ultimate authority. I
12:50
Speaker 1: saw it on YouTube. It must be right. I saw
12:52
Speaker 1: it an archive dot X, it must be true. I
12:55
Speaker 1: don't know the physics is sound or if it's actually right,
12:57
Speaker 1: but it is something people actually say in the A
13:00
Speaker 1: is its community. So there's that much cosmological access of evil.
13:04
Speaker 1: That's what we'll dig get into today. And so, as usually,
13:06
Speaker 1: we were wondering how many people out there had heard
13:08
Speaker 1: of this cosmological access of evil and whether they have
13:11
Speaker 1: any idea about what it means. So Daniel went out
13:14
Speaker 1: there into the Internet to ask people this question. Here's
13:16
Speaker 1: what they had to say on a guess cosmological something
13:20
Speaker 1: to do with very large scale structures in the universe.
13:24
Speaker 1: Access of evil. Perhaps it's something to do with the
13:28
Speaker 1: way that certain fields are calculated and there's some weird
13:33
Speaker 1: mathematical structure that causes problems. I have no idea. I
13:38
Speaker 1: have no idea. I couldn't even begin to guess. It
13:43
Speaker 1: sounds familiar, but I don't know what it is. Probably
13:48
Speaker 1: i'm watching too much theory. I can tell you right
13:50
Speaker 1: off the bat, I'm stealing that and that is going
13:52
Speaker 1: to be the name for my new punk rock band.
13:55
Speaker 1: But aside from that, I have no clue. My only
13:58
Speaker 1: guess is that that is what we would call the
14:01
Speaker 1: things that are going to be responsible for the end
14:03
Speaker 1: of the universe. So maybe dark energy and entropy are
14:08
Speaker 1: the cosmological access of evil. The cosmological access of evil
14:13
Speaker 1: is the nexus in the universe where everything that is
14:16
Speaker 1: evil intersects. Think the dark side of the force live,
14:21
Speaker 1: because evil backwards is life. What does that have to
14:24
Speaker 1: do with the access of evil? I guess that's a
14:27
Speaker 1: good enough answer because I have no idea either, So
14:30
Speaker 1: I'll go with it's something with the bow taste void
14:33
Speaker 1: and the Great Attractor and the void is somehow funneling
14:37
Speaker 1: all of the matter from the universe into the Great
14:40
Speaker 1: Attractor to create a super giant black hole that's going
14:43
Speaker 1: to swallow everything. Does that sound that's an access of evil?
14:47
Speaker 1: We could throw mustache twirling enemies in there, or I
14:50
Speaker 1: guess go t Jorge because he was in one of
14:52
Speaker 1: those are Parallel Universe episodes before. So I have no
14:56
Speaker 1: idea what the cosmological axis of evil. It's how I
15:01
Speaker 1: see Austin powers and battling. The cosmogical access of evil
15:08
Speaker 1: um in my brain when I read this question, I
15:12
Speaker 1: I don't know anything beyond that. All Right, nobody has
15:16
Speaker 1: any idea, Daniel. It has not broken out of the
15:20
Speaker 1: physics community out into the larger population. And that's our
15:24
Speaker 1: job is to funnel the craziest, funnest, most interesting, wackiest
15:28
Speaker 1: ideas that are poorly named out into the larger community. Yeah,
15:31
Speaker 1: so you call an acts of evil because I guess
15:33
Speaker 1: an access is sort of like a direction, and you're
15:36
Speaker 1: saying that maybe this direction is sort of evil in
15:39
Speaker 1: the sense that it sort of ruins the universe or
15:41
Speaker 1: ruins your sort of perfect symmetry picture of the universe. Yeah,
15:45
Speaker 1: I think that's right, although historically and sort of philosophically,
15:49
Speaker 1: it's fascinating because I think, you know, the idea that
15:53
Speaker 1: the universe doesn't have a preferred direction went up against
15:56
Speaker 1: a lot of theological friction, you know, five years ago,
15:59
Speaker 1: because people preferred the concept, you know, that the Earth
16:02
Speaker 1: was at the center of the universe and in a
16:04
Speaker 1: special location and sort of at the heart of the cosmos.
16:07
Speaker 1: So the idea that the universe didn't have a preferred
16:10
Speaker 1: direction was sort of seen as evil five years ago,
16:14
Speaker 1: and now doubting that idea is again seen as evil.
16:17
Speaker 1: So in that sense, maybe evil is just like you know,
16:19
Speaker 1: the upstart. Well, I think if there's anything movies has
16:23
Speaker 1: taught us is that evil is a relative cosmet you know,
16:28
Speaker 1: maybe not the Marvel movies, but you know, more art
16:30
Speaker 1: artful movies. Yeah, I think it's a pretty ridiculous name.
16:33
Speaker 1: You mean, like in religious times or in a religious sense,
16:36
Speaker 1: like you want the universe who have a preferred direction,
16:39
Speaker 1: you know, you want your DT to have some sort
16:41
Speaker 1: of point of view. Well, I think the Catholic Church,
16:43
Speaker 1: for example, was not a big fan of the idea
16:46
Speaker 1: that the Earth was not at the center of the cosmos.
16:48
Speaker 1: Galileo spent a long time under house arrest for insisting
16:51
Speaker 1: that it was. And I don't think that Copernicus was
16:53
Speaker 1: like number one favorite person by the pope either. So
16:56
Speaker 1: I think that you know, scientists got a lot of
16:58
Speaker 1: flat several hundred years ago first suggesting that the Earth
17:01
Speaker 1: was not at the center of the cosmos. But now
17:03
Speaker 1: there's maybe an inkling or a suggestion that maybe the
17:06
Speaker 1: universe does have a special access, a special direction it likes,
17:10
Speaker 1: and so break it that ros what does that mean
17:12
Speaker 1: and where does that come from? So we've been operating
17:14
Speaker 1: under this assumption for a long time now that we
17:17
Speaker 1: don't have a special place in the universe, that there
17:19
Speaker 1: is no special place, that there is no preferred direction.
17:22
Speaker 1: And this really has grown out of like the Copernican principle,
17:25
Speaker 1: you know, from five years ago, and these days we
17:27
Speaker 1: call it the cosmological principle because we say it even
17:30
Speaker 1: more broadly. We say that the whole universe is homogeneous,
17:34
Speaker 1: is isotropic, that on a large scale, everywhere in the
17:37
Speaker 1: universe is basically the same. There's no center, there's no edge,
17:41
Speaker 1: there's no place that's different from any other place. And
17:44
Speaker 1: so if you spotted a deviation from that if you like,
17:46
Speaker 1: detected something which seemed to prefer a direction that would
17:50
Speaker 1: spoil something really deeply fundamental at the heart of basically
17:53
Speaker 1: all of modern cosmology. Are those two things tied together,
17:56
Speaker 1: you know, like a special preferred location and I prefer direction?
18:00
Speaker 1: Or are those you know independent, like can you have
18:03
Speaker 1: a preferred direction without a preferred location? Those are independent?
18:06
Speaker 1: There in the same family of ideas, but there are
18:08
Speaker 1: actually two separate things, and you know, it really is interesting.
18:11
Speaker 1: The idea that the universe has no preferred location is
18:15
Speaker 1: a symmetry, right. It says you do an experiment here
18:18
Speaker 1: and you do an experiment there, you get the same answer.
18:20
Speaker 1: Space is the same here and there. That leads to
18:22
Speaker 1: a conservation law. We talked about it once in the podcast.
18:25
Speaker 1: I mean Nuther's theorems tells you that every symmetry gives
18:29
Speaker 1: a conservation law. And in the case of having no
18:31
Speaker 1: preferred location, that's why momentum is conserved. And in the
18:34
Speaker 1: case of rotation, the idea that if you rotate the
18:37
Speaker 1: universe you should always get the same answers to your experiments.
18:39
Speaker 1: That's what gives you conservation of angular momentum. So there
18:42
Speaker 1: are two separate ideas, but they are closely connected, right,
18:46
Speaker 1: They're both connected to momentum. But I guess when that
18:48
Speaker 1: people start questioning whether there was a preferred direction, because
18:52
Speaker 1: I've never heard of this idea that it could have
18:53
Speaker 1: a preferred direction, right, it comes out of some observations
18:56
Speaker 1: that have been made in the last few years. People
18:58
Speaker 1: have been assuming that things are equally smooth and the
19:02
Speaker 1: same in every direction, but recently there's been this sort
19:05
Speaker 1: of like strange, unexplained alignment of various measurements that should
19:09
Speaker 1: be random, And when you see a bunch of coincidences
19:12
Speaker 1: line up, you start to wonder, like, are these coincidences
19:15
Speaker 1: or are these sort of like the first clues into
19:18
Speaker 1: a new way to look at the universe? Interesting? So
19:21
Speaker 1: this is based on some experimental results, Yeah, these are
19:24
Speaker 1: unexplained coincidences that have people starting to wonder if the
19:28
Speaker 1: universe might actually have a preferred direction. Well, you make
19:31
Speaker 1: it seem like a conspiracy or like a sort of secret,
19:35
Speaker 1: secret undercurrent, some dark underbelly kangaroo pouch of the universe,
19:39
Speaker 1: exactly like some access of evil hatching some plan to
19:42
Speaker 1: spoil our view of cosmology. Bunch of us hands thinking
19:45
Speaker 1: about how to keep from falling out the Earth. Yeah,
19:48
Speaker 1: and I think it's worth exploring for a moment what
19:50
Speaker 1: this principle that we're doubting means the idea of the
19:53
Speaker 1: universe is the same everywhere, because obviously it's not exactly
19:57
Speaker 1: the same everywhere. Like, you know, there's a star here
19:59
Speaker 1: and it is not a star there. There's a galaxy
20:02
Speaker 1: over here, but it's not a galaxy over there. It's
20:04
Speaker 1: not true that every place in the universe is exactly identical.
20:07
Speaker 1: It's a statement we make about very very large scales,
20:11
Speaker 1: like if you really zoom out out past galaxies and
20:14
Speaker 1: past galaxy clusters, out to galaxy superclusters, and you look
20:18
Speaker 1: at sort of like the filaments in the foam of
20:20
Speaker 1: the largest scale structure of the universe, things should be
20:23
Speaker 1: about the same everywhere. It just made me think, like,
20:26
Speaker 1: is it possible to go out there into space and
20:28
Speaker 1: measure gravity and whether or not gravity kind of pulls
20:32
Speaker 1: you in one particular direction. Would I tell you if
20:35
Speaker 1: you're at the edge of a universe, a finite universe
20:37
Speaker 1: or not. Yeah, and that would be a deviation, right,
20:39
Speaker 1: and so on the very largest scales, you should basically
20:42
Speaker 1: feel no effective gravity because there should be an even
20:44
Speaker 1: distribution of stuff in every direction. Pick a random place
20:48
Speaker 1: in the universe and there should be you know, like
20:50
Speaker 1: superclusters over there and superclusters over here, and in the
20:52
Speaker 1: end they should all roughly balance. Of course, if you
20:55
Speaker 1: land near a black hole, you're gonna feel some gravity,
20:57
Speaker 1: but on average there should be you know, effective bugging.
21:00
Speaker 1: And that comes from you know, we think the universe
21:02
Speaker 1: was created smoothly and created homogeneously, and you know, the
21:06
Speaker 1: variations that we do see the fact that there's a
21:08
Speaker 1: galaxy here and not a galaxy there, those come from
21:11
Speaker 1: the little perturbations, the little fluctuations in that smooth beginning
21:15
Speaker 1: of the universe. I see. All right, so there's some
21:18
Speaker 1: experimental measurements that tell us that maybe things are not homogeneous,
21:21
Speaker 1: that maybe things do have a preferred direction. So let's
21:24
Speaker 1: get into this secret result. But first let's take a
21:27
Speaker 1: quick break. All right, we are determining whether the universe
21:43
Speaker 1: has a specific direction it likes or dislikes, or I
21:46
Speaker 1: guess we're asking whether the universe leads a certain way
21:49
Speaker 1: Daniel right, or what's the universe's orientation? That's right? Is
21:52
Speaker 1: it a chocolate universe. Is it a vanilla universe? I
21:56
Speaker 1: was gonna say, you know, bananas or Paris? Is it
21:59
Speaker 1: more of all or is it d C? Right? Yeah,
22:03
Speaker 1: and that would determine whether I like the universe or not.
22:06
Speaker 1: Although both of those universes have villains in it, right,
22:08
Speaker 1: Which do you think actually has more? Which is the
22:10
Speaker 1: darker universe? Oh? For sure? D see in the Marvel universe,
22:14
Speaker 1: people are more more through dimensional. I think evil has
22:17
Speaker 1: more dimensions to it. There's certainly more ridiculous jokes in
22:19
Speaker 1: the Marvel universe. Alright. So we were talking about how
22:22
Speaker 1: maybe there's some sort of result or some sort of
22:24
Speaker 1: experimental observation that maybe it doesn't look like it's random
22:28
Speaker 1: and maybe hints that that maybe there could be a
22:30
Speaker 1: special direction in the universe. Yeah, and there is actually
22:33
Speaker 1: several of these measurements which together are very suggestive because
22:37
Speaker 1: they're all sort of line up to seeing to prefer
22:39
Speaker 1: one direction. And the first one comes from information which
22:42
Speaker 1: would be very familiar to listeners of the podcast. It's
22:44
Speaker 1: the cosmic microwave background radiation. This is light that comes
22:48
Speaker 1: from the very very early universe. Remember when the universe started,
22:51
Speaker 1: it was very hot, and very dense, but it was
22:53
Speaker 1: also very opaque. It was sort of like the center
22:55
Speaker 1: of the sun when things are really hot and nasty
22:58
Speaker 1: than light gets abs or by other molecules as soon
23:01
Speaker 1: as it's made. But then the universe expanded and it cooled,
23:04
Speaker 1: and at some moment, around three eighty thousand years after
23:08
Speaker 1: the Big Bang, it cooled enough to become transparent. And
23:11
Speaker 1: so the cosmic microwave background radiation are those photons that
23:15
Speaker 1: were created at that moment, the first moment the universe
23:18
Speaker 1: was transparent, and are still flying around the universe today. Yeah,
23:21
Speaker 1: Like if you point your antenna anywhere in space, you
23:24
Speaker 1: sort of get a hum, right, you get a little
23:26
Speaker 1: like a static hiss that it actually turns out to
23:29
Speaker 1: be from the Big Bang. Yeah, and the universe was
23:31
Speaker 1: super duper hot back then. It was like three thousand
23:34
Speaker 1: degrees kelvin. But in the fourteen billion years that those
23:37
Speaker 1: photons have been flying around, the universe has expanded and
23:40
Speaker 1: so they've been sort of red shifted. They've been pulled
23:42
Speaker 1: into longer wavelength which we then translate into a temperature.
23:46
Speaker 1: And so the temperature of the CNB is around two
23:49
Speaker 1: point seven kelvin, and so it's very very long wavelength,
23:52
Speaker 1: which is why like you can't see the CMB with
23:54
Speaker 1: your eyes, you need a special antenna. And it was discovered,
23:58
Speaker 1: you know, several decades ago. We have a whole episode
24:00
Speaker 1: about it, and it was really nice piece of evidence
24:02
Speaker 1: that the universe was at one point a very hot
24:05
Speaker 1: and dense plasma. But it's not like a perfectly smooth picture.
24:08
Speaker 1: It is kind of like bumpy and lumpy, and it
24:10
Speaker 1: has a certain texture to it if you point your
24:12
Speaker 1: intent and want in some directions that the sort of
24:15
Speaker 1: the sky feels hotter than than other spots. Yeah, and
24:17
Speaker 1: it's a great way to visualize what we mean by
24:19
Speaker 1: the universe being like smooth and isotropic, because if you
24:24
Speaker 1: look at the CNB, there are variations and it there's
24:26
Speaker 1: little spots that are hotter and little spots that are colder.
24:28
Speaker 1: But that doesn't mean that any preferred direction. It just
24:30
Speaker 1: means that there are some random quantum fluctuations in the
24:33
Speaker 1: early universe over this smooth background, and those fluctuations are
24:37
Speaker 1: exactly what led to you know, like a galaxy forming
24:39
Speaker 1: here or a supercluster forming over there. These were like
24:42
Speaker 1: the seeds of structure of the later universe, and so
24:45
Speaker 1: we study this in great detail to understand exactly how
24:48
Speaker 1: the universe formed, and those seeds of structure really controlled
24:52
Speaker 1: the rest of the evolution of the universe. So it's
24:54
Speaker 1: super interesting to look at that. And that's one of
24:57
Speaker 1: the scale in which we study the universe to under
25:00
Speaker 1: dan whether it's smooth. We'd like take a big chunk
25:02
Speaker 1: of the CMB and say, is this, on average the
25:04
Speaker 1: same as another big chunk of the CMB. So mostly
25:07
Speaker 1: it's very smooth, but you're right, there are these variations,
25:09
Speaker 1: like one part in a hundred thousand or sponsored a
25:12
Speaker 1: little hotter or a little colder, right, And you sort
25:14
Speaker 1: of look at a picture of it, it sort of
25:16
Speaker 1: looks like a camouflage pattern almost in a way, right,
25:18
Speaker 1: Like it's sort of blobby, and it has these kind
25:21
Speaker 1: of texture to it. And that's when that has been exaggerated. Right,
25:24
Speaker 1: If you just looked at a plot of CMB on
25:27
Speaker 1: a normal scale, it would look perfectly smooth. It's only
25:30
Speaker 1: when you like really zoom in or you exaggerate these
25:33
Speaker 1: fluctuations that you can even see them. And we've been
25:36
Speaker 1: sending satellites up into the sky to sample it for
25:38
Speaker 1: decades now, and we started out looking like a very
25:41
Speaker 1: fuzzy picture of it, and then a clear and crisper
25:44
Speaker 1: and crisper, and now we can see it like with
25:46
Speaker 1: really high resolution and great accuracy. We can measure all
25:49
Speaker 1: these ripples and allows for incredible studies of the nature
25:52
Speaker 1: of the universe. The shapes of those fluctuations tell us
25:54
Speaker 1: about like how much dark matter there was back then
25:56
Speaker 1: in the early universe, and how much dark energy there was,
25:59
Speaker 1: and how the universe is expanded since then. It's an
26:01
Speaker 1: incredible treasure trove of information about how the universe looked
26:05
Speaker 1: back then at the very beginning, and how it's evolved
26:08
Speaker 1: in the meantime. Yeah, and so it's sort of textured
26:10
Speaker 1: like a camouflage pattern, and so which sort of varies
26:14
Speaker 1: locally in like a small spot. But if you sort
26:16
Speaker 1: of step away from the camouflage pattern, it all sort
26:19
Speaker 1: of generally looks the same, or it looks sort of
26:21
Speaker 1: homogeneously and a textured But I guess here you're saying
26:24
Speaker 1: that maybe there's a larger a symmetry to it, like
26:27
Speaker 1: maybe some areas of the sky are differently textured than
26:32
Speaker 1: other areas of the sky. That's right, It turns out
26:34
Speaker 1: there is a little bit of an asymmetry. If you
26:35
Speaker 1: look at the top half of the sky, that is
26:38
Speaker 1: the part of the universe that's like above the plane
26:41
Speaker 1: of the Solar System, it turns out to be a
26:43
Speaker 1: tiny little bit colder. Those photons have a wavelength it's
26:46
Speaker 1: a little bit longer, And if you look down sort
26:49
Speaker 1: of the bottom half of the Solar system, then that
26:52
Speaker 1: portion of the sky is a little bit hotter. Those
26:54
Speaker 1: photons are a little bit bluer. Well, that makes sense, right,
26:57
Speaker 1: Australia is a little bit hotter. In general, it's so
27:01
Speaker 1: hot it's heating the entire universe. That's just kidding. But wait,
27:05
Speaker 1: when you say like the top half in the bottom half,
27:07
Speaker 1: do you mean like the north, like if you look
27:09
Speaker 1: in the northern hemisphere of the sky, or do you
27:13
Speaker 1: mean like some other direction? I mean roughly the north,
27:16
Speaker 1: but I'm talking about relative to the Solar system. So
27:18
Speaker 1: the Sun has a north pole and a south pole,
27:20
Speaker 1: and the planets orbited around the Sun in a plane
27:23
Speaker 1: that's perpendicular to the Sun's north pole and south pole.
27:26
Speaker 1: I mean, like the disc that where all the planets
27:28
Speaker 1: are spinning, it sort of forms a like a plate. Yeah,
27:31
Speaker 1: it forms a plate, and the Sun's north pole south
27:34
Speaker 1: pole goes like straight up and down through that plate,
27:36
Speaker 1: and the Earth moves along that plane. We call it
27:38
Speaker 1: the ecliptic. The Earth is a little bit tilted, so
27:40
Speaker 1: the Earth's north and the Sun's north are not quite aligned.
27:44
Speaker 1: But when we study these things about the universe, we
27:46
Speaker 1: try to orient ourselves relative to the Sun or to
27:48
Speaker 1: the center of the galaxy rather than to the Earth.
27:51
Speaker 1: Turns out that the cosmic microwave background radiation in the
27:54
Speaker 1: Sun's northern hemisphere, that is, the portion of the universe
27:57
Speaker 1: that's like above the plane of the Solar System, is
28:00
Speaker 1: a little bit colder than the rest of the universe
28:02
Speaker 1: below the Solar System. Interesting, and so we we're sure
28:06
Speaker 1: it's not like an error in measurement, like maybe they're
28:08
Speaker 1: using different units done in Australia or Argentina where they're
28:12
Speaker 1: measuring this. No, it's definitely a real thing. It's super fascinating,
28:16
Speaker 1: and there's two things to understand about it. One is
28:18
Speaker 1: like what does it mean? And the other is what
28:21
Speaker 1: does it mean that it's oriented with the plane of
28:23
Speaker 1: the Solar System, Like it's not necessarily a huge surprise
28:26
Speaker 1: that there is an asymmetry because we can interpret this
28:29
Speaker 1: as the Earth or the Solar System at least moving
28:33
Speaker 1: through the cosmic microwave background radiation. Like the universe doesn't
28:37
Speaker 1: have to have a preferred location or preferred direction or velocity.
28:41
Speaker 1: But the stuff in the universe, that plasma that made
28:44
Speaker 1: that light fourteen billion years ago, it was somewhere, It
28:48
Speaker 1: had a location, had a rest frame, a place where
28:50
Speaker 1: you could say, okay, I'm at rest relative to that plasma.
28:53
Speaker 1: And so then you can say, well, you can be
28:55
Speaker 1: at rest relative to this constic microwave background radiation. And
28:59
Speaker 1: it turns out that we sort of moving through that radiation,
29:02
Speaker 1: which red shifts some of it and blue shifts other
29:04
Speaker 1: parts of it. Right. It's it's almost like if you're
29:07
Speaker 1: running really fast towards a flashlight being pointed at you,
29:10
Speaker 1: you would see the light slightly not perfectly white, but
29:13
Speaker 1: a slightly different color. And if someone was pointing a
29:16
Speaker 1: flashlight at you running away, you would also when you
29:18
Speaker 1: look back, see that light slightly shifted in color. Yeah,
29:22
Speaker 1: and so it's nice to think about the cosmic microwave
29:25
Speaker 1: background radiation as sort of a cosmic rest frame something
29:29
Speaker 1: against which you can measure your velocity. That doesn't mean
29:31
Speaker 1: the universe has a rest frame, right, It's just like
29:34
Speaker 1: these things do exist. They're out there, they're shining lights
29:37
Speaker 1: at us, and so you can measure these Doppler shifts
29:39
Speaker 1: as you said, the red shifting and blue shifting. And
29:41
Speaker 1: so we are moving through the CNB like three hundred
29:44
Speaker 1: and seventy kilometers per second. It's almost like there are
29:47
Speaker 1: flashlights pointed at us from every direction. That's kind of
29:50
Speaker 1: the CNB, right, And so if we're moving with and
29:53
Speaker 1: then we're going to see some of those flashlights a
29:55
Speaker 1: different color than the ones, for example, behind us. Yeah,
29:57
Speaker 1: I think it's a point of confusion here. A lot
29:59
Speaker 1: of people writing a skiing like why is it we
30:01
Speaker 1: can see the CNB right now and not earlier or
30:04
Speaker 1: not later? And I think that the conceptual idea here
30:07
Speaker 1: to unpack is that the CNB was everywhere. This plasma
30:10
Speaker 1: filled the whole universe and generated light in every direction.
30:14
Speaker 1: What we are seeing now is just the portion of
30:17
Speaker 1: it which happens to be arriving right now. So, as
30:19
Speaker 1: you said, imagine people shining flashlights fourteen billion years ago
30:22
Speaker 1: in every direction, which flashlights would we see right now,
30:25
Speaker 1: we'd see like a shell of flashlights that are super
30:29
Speaker 1: far away from us that happened to arrive right now.
30:31
Speaker 1: As time goes on, we see a different slice of
30:34
Speaker 1: the CMB, so we don't see the whole CNB. We
30:37
Speaker 1: see sort of like a spherical shell of it at
30:38
Speaker 1: any moment. All right, So us moving through this radiation
30:42
Speaker 1: this light would explain why it feels cooler and hotter
30:46
Speaker 1: on one side of the solar system north pole or not.
30:48
Speaker 1: But that doesn't mean that the universe has it preferred
30:51
Speaker 1: the direction. It just means we're moving through it in
30:52
Speaker 1: as certain direction, that's right. The weird thing is that
30:55
Speaker 1: it's aligned with the plane of our solar system, Like
30:58
Speaker 1: why is that the CNB having some rest frame and
31:02
Speaker 1: us moving through it no big deal? Why are we
31:04
Speaker 1: moving through it exactly aligned with the plane of our
31:07
Speaker 1: solar system because our solar system, you know, has no
31:11
Speaker 1: connection to the CMB. It just is what it is.
31:14
Speaker 1: It's not even that well aligned with the plane of
31:16
Speaker 1: our galaxy, which is not well aligned with the CMB.
31:19
Speaker 1: So it's a little bit odd. It's like strange, maybe
31:22
Speaker 1: a coincidence, maybe not the plane of our solar system
31:26
Speaker 1: is aligned with this other cosmic plane. Well, if it's
31:29
Speaker 1: not a coincidence, what else could it be. Well, that's
31:32
Speaker 1: the question. Like, if it's not coincidence and needs to
31:34
Speaker 1: have some explanation, there needs to be some mechanism that says, like,
31:37
Speaker 1: all right, the universe has a preferred direction which causes
31:40
Speaker 1: both of these things to line up in this direction.
31:43
Speaker 1: If you didn't know what a compass was, and you
31:44
Speaker 1: saw two compasses and they're like, oh, look, the red
31:47
Speaker 1: arrows are both pointing in the same direction, I wonder
31:49
Speaker 1: why You've got to dig deeper and find some like
31:51
Speaker 1: mechanism that explains what aligns those two in the same direction.
31:55
Speaker 1: And so we're just the beginning of like understanding what
31:58
Speaker 1: that might be. You know, large scale gravitational effects on
32:02
Speaker 1: the outside of our observable universe could like distort the
32:05
Speaker 1: whole universe in a way that makes things aligned in
32:08
Speaker 1: this way. For example, Oh, I think I see what
32:11
Speaker 1: you're saying. You're saying that the fact that we see
32:13
Speaker 1: the CMB colder in one direction and harder in another direction,
32:16
Speaker 1: it's not evidence that the universe is somehow biased. It's
32:20
Speaker 1: the coincidence that our solar system is aligned to this direction.
32:23
Speaker 1: That's the weird thing. Like maybe whatever caused us to
32:27
Speaker 1: be moving in that direction and whatever caused our solar
32:29
Speaker 1: system to be pointed in that direction, maybe it's somehow related. Yes,
32:33
Speaker 1: and it's a little weird, and you might just brush
32:35
Speaker 1: it off and say like, oh, it's just coincidence. Whatever.
32:38
Speaker 1: They both have to have a direction. But there are
32:40
Speaker 1: other things aligned with our solar system that have been
32:43
Speaker 1: like slowly piling up the coincidences enough that people are like,
32:47
Speaker 1: maybe this is a thing. All right, yeah, so what
32:49
Speaker 1: are those things? Well, the second one also relates to
32:51
Speaker 1: the CMB because people were wondering, like are we moving
32:55
Speaker 1: relative to the CNB or is the whole universe moving
32:58
Speaker 1: relative to the CNB? Like is the entire current existing
33:03
Speaker 1: stuff in the universe? Is that at rest with respect
33:05
Speaker 1: to the CNB. So people try to make another measurement
33:08
Speaker 1: of our velocity independent of the CNB. They try to
33:11
Speaker 1: measure the Earth or the solar systems velocity relative to
33:14
Speaker 1: the whole universe of stuff that exists right now, I
33:17
Speaker 1: mean the stuff that we can see, the stuff that
33:19
Speaker 1: we can see. Yes, And so instead of using the
33:22
Speaker 1: CMB they're like, let's look at the stuff that exists
33:24
Speaker 1: right now, the stuff we can see. So what they
33:26
Speaker 1: did is they looked at a bunch of quasars. These
33:28
Speaker 1: are very energetic black holes the hearts of galaxies and
33:32
Speaker 1: black holes of course are themselves dark, but these black
33:34
Speaker 1: holes are so powerful they have millions or billions of
33:38
Speaker 1: times the mass of the Sun that they create incredible
33:40
Speaker 1: radiation around them because of the tidal forces causing friction
33:44
Speaker 1: in the gases that are falling into the black holes.
33:46
Speaker 1: So these are some of the brightest things in the universe,
33:49
Speaker 1: which is really helpful because then you can see a
33:51
Speaker 1: lot of them, and you can see them really far away,
33:53
Speaker 1: and you can see the distortion in them because if
33:55
Speaker 1: they're like shifted in one frequency or shifted in another frequency,
33:58
Speaker 1: you can use that to measure our velocity relative to
34:01
Speaker 1: these quasars. So people ask this question, like, are we
34:04
Speaker 1: moving relative to like all the quasars that we can
34:07
Speaker 1: see out there in the universe. M I see. It's
34:09
Speaker 1: trying to get a sensor of like in the observable universe,
34:12
Speaker 1: are we moving left or right? And what they found
34:15
Speaker 1: is that we are moving relative to those quasars we're
34:19
Speaker 1: moving around six hundred kilometers per second relative to those quasars,
34:23
Speaker 1: which is a big surprise. First of all, people are like,
34:25
Speaker 1: what why are we moving so fast relative to like
34:28
Speaker 1: the average stuff in the universe. But when you say
34:30
Speaker 1: we're moving, do you mean like our solar system or
34:33
Speaker 1: or our Milky Way or our galaxy cluster? What? What
34:36
Speaker 1: do you mean? I mean our solar system? Okay, but
34:38
Speaker 1: don't we know how our solar system is moving relative
34:41
Speaker 1: to our the Milky Way? Yeah? Absolutely we do. All right,
34:44
Speaker 1: So you're saying that our galaxy itself is sort of
34:46
Speaker 1: moving through through the observable universe. Yeah, our galaxy seems
34:50
Speaker 1: to be moving through the observable universe. And the really
34:53
Speaker 1: surprising thing is that it seems to be moving relative
34:55
Speaker 1: to these quasars in the direction aligned with this cmb anisotropy.
35:01
Speaker 1: That is, it seems to be moving in the same
35:02
Speaker 1: direction along the Sun's north and south pole. Well that's
35:06
Speaker 1: a little weird, I guess, because you know, like we're
35:09
Speaker 1: spinning on Earth, and the Earth is spinning around the Sun,
35:11
Speaker 1: and the Sun is spinning around the galaxy, and the
35:14
Speaker 1: gacy I imagine is spinning around sort of the larger
35:16
Speaker 1: galaxy cluster. Are you saying, I guess I'm not sure
35:20
Speaker 1: quite what you're saying. You're saying, like all of those
35:22
Speaker 1: sort of velocity vectors, all those directions of motion are
35:25
Speaker 1: somehow pointing in the same direction right now, wouldn't that change? Like,
35:29
Speaker 1: aren't we moving sometimes in this direction and that direction
35:31
Speaker 1: as we're going around the Sun or the galaxy? Sure,
35:34
Speaker 1: the Earth is moving around the Sun, and the Sun
35:37
Speaker 1: is moving around the center of the galaxy, and the
35:39
Speaker 1: galaxy is orbiting the center of the galaxy cluster, and
35:42
Speaker 1: so each of those has a velocity and a direction
35:46
Speaker 1: relative to the CNB. Right now, we're talking about one
35:50
Speaker 1: of those in particular, which is just the velocity of
35:53
Speaker 1: the Solar system, and that velocity vector seems to point
35:56
Speaker 1: right towards the direction of the hotter part of the
35:59
Speaker 1: c m BE. So that's really interesting and also seems
36:03
Speaker 1: to be aligned with the direction of those quasars. And
36:06
Speaker 1: there's no reason to think that these three directions should
36:09
Speaker 1: be aligned. They could have been anything that The question
36:12
Speaker 1: of the Earth's velocity and the galaxy's velocity are separate,
36:16
Speaker 1: right those are different vectors, But the Solar system velocity
36:19
Speaker 1: is aligned with the CNB and with those quasars, which
36:23
Speaker 1: is somehow aligned with the direction of the solar system.
36:26
Speaker 1: Is it also aligned with the direction of the Milky Way.
36:29
Speaker 1: Is our solar system disc in the disc of the
36:32
Speaker 1: Milky Way? It's not right. Our solar system is actually
36:35
Speaker 1: tilted relative to the disc of the Milky Way. So
36:37
Speaker 1: this required just our solar system to somehow be weirdly
36:41
Speaker 1: aligned with this two cosmic axes, the CMB and the quaisars.
36:47
Speaker 1: It's a very strange coincidence. But I guess if we
36:49
Speaker 1: wait a few you know, hundred years or a thousand years,
36:52
Speaker 1: would in our direction change because we're going around the galaxy.
36:55
Speaker 1: So our velocity relative to the galaxy does change as
36:58
Speaker 1: we move around the galaxy. The period of that is
37:01
Speaker 1: you know, very very long. It's millions and millions of years.
37:04
Speaker 1: But the direction of the solar system shouldn't change. Our
37:07
Speaker 1: conservation of angularmentum should mean that the basically the north
37:10
Speaker 1: and south pole of the Sun shouldn't change even as
37:12
Speaker 1: it moves around the center of the galaxy. The same
37:16
Speaker 1: way like the direction of the earth tilt doesn't change
37:18
Speaker 1: as it moves around the Sun. I see, but you're
37:21
Speaker 1: saying that, then the Milky Way is moving in the
37:23
Speaker 1: same direction as our Solar system is pointed at, which
37:26
Speaker 1: is the same as what we measure with the CNB.
37:29
Speaker 1: The Solar system is aligned with the direction of the CMB,
37:32
Speaker 1: but the Milky Way is a little bit tilted relative
37:34
Speaker 1: to the Solar system, so it's not quite as a line.
37:37
Speaker 1: And there's a third weird coincidence in the same direction.
37:41
Speaker 1: What is it? So people are constantly looking for things
37:43
Speaker 1: that are weirdly lined, and so what they did is
37:46
Speaker 1: they looked at the spins of galaxies. You can look
37:49
Speaker 1: out deep into the universe and look at all these
37:51
Speaker 1: galaxies and you can measure which direction they're spinning in
37:54
Speaker 1: Like a galaxy is like a little swirl, and you
37:56
Speaker 1: can tell which direction it's spinning, like as it's spinning
37:59
Speaker 1: left or is it spinning based on the direction that
38:01
Speaker 1: the arms are sort of trailing behind it. And you
38:03
Speaker 1: can look out and you can count like how many
38:05
Speaker 1: of them are clockwise and how many they are anti clockwise.
38:07
Speaker 1: And you might expect if the universe is random and
38:10
Speaker 1: isotropic and no preferred directions, for that to be like
38:13
Speaker 1: roughly even everywhere well, what they see is that there
38:15
Speaker 1: isn't asymmetry, and they see this asymmetry again aligned with
38:19
Speaker 1: the plane of the Solar System. That galaxies you can
38:22
Speaker 1: see above the ecliptic are more clockwise, and the galaxy
38:26
Speaker 1: you can see below the ecliptic tend to be more
38:28
Speaker 1: counterclockwise swirling. What wouldn't that be explained by the fact
38:33
Speaker 1: that you know, like you're looking at the bottoms of
38:36
Speaker 1: some galaxies and you're looking at the tops of some galaxies,
38:38
Speaker 1: depending on how you look at them. Yeah, but if
38:40
Speaker 1: they're randomly oriented, you should see the same number of
38:43
Speaker 1: clockwise and counterclockwise, like the same galaxy. If it's spinning
38:46
Speaker 1: in one direction, you'll see a clockwise or counterclockwise depending
38:49
Speaker 1: on which side of it you are on. But if
38:52
Speaker 1: they're all in random places and all in random directions,
38:54
Speaker 1: you should see the same number in every direction. It's
38:57
Speaker 1: like if you throw a million coins in a room him,
39:00
Speaker 1: you should have the same number of heads and tails
39:01
Speaker 1: in every direction. Right, But we see an asymmetry. We
39:04
Speaker 1: see like more heads over here and more tails over here,
39:06
Speaker 1: which is weird already, But that asymmetry is then aligned
39:10
Speaker 1: with these other asymmetries. We see the one in the
39:12
Speaker 1: CMB and the motion relative to the quays AARs interesting.
39:15
Speaker 1: You mean it's sort of like the whole toilet flushing
39:17
Speaker 1: in the different direction of the southern hemistry, right, yeah, yeah,
39:21
Speaker 1: though I don't know if that's really a thing. Yeah,
39:23
Speaker 1: I think it is a thing, right, because we know
39:25
Speaker 1: that the hurricanes spin in different directions, right, they do
39:29
Speaker 1: spin in different directions because of the corial is for us.
39:31
Speaker 1: You're absolutely right, but I don't know if that actually
39:33
Speaker 1: controls the direction in which toilets flush. So Australian listeners,
39:36
Speaker 1: let us know, but don't all flush at the same time,
39:39
Speaker 1: because you're gonna drain the continent. You'll slow the earth
39:42
Speaker 1: spin if you'll flush at the same time. All right, Well,
39:45
Speaker 1: so there's a lot of interesting coincidence. Is that maybe
39:48
Speaker 1: tell you that the universe has a preferred direction? And
39:50
Speaker 1: so let's get into what this all means. But first
39:52
Speaker 1: let's take a quick break. All right, Daniel, here's a
40:07
Speaker 1: now our favorite question. What does it all mean? Man?
40:11
Speaker 1: What does it mean that the universe has a preferred directions?
40:13
Speaker 1: I guess the theory is, the hypothesis is that the
40:16
Speaker 1: universe has some sort of preferred direction that is somehow
40:19
Speaker 1: making galaxies also of spinning roughly the same direction, and
40:23
Speaker 1: it's making our solar system roughly spinning that direction, and
40:27
Speaker 1: everyone's moving in that direction. To what what does that mean?
40:30
Speaker 1: We really don't know what it means. And mainstream cosmology
40:33
Speaker 1: is very certain that it's all just random, that it's fluctuations.
40:36
Speaker 1: They're very strong believers in the cosmological principle of the
40:39
Speaker 1: universe is the same everywhere and that there is no
40:41
Speaker 1: preferred direction. It would just be very difficult for them
40:44
Speaker 1: to give up this principle, which is precisely why it's
40:46
Speaker 1: so much fun to think about and to talk about,
40:48
Speaker 1: because it's those kind of like huge mental revolutions that
40:52
Speaker 1: are the best moments in physics. And so what does
40:54
Speaker 1: it mean. It means that people should spend some time
40:57
Speaker 1: thinking about how it might be possible to have a
41:00
Speaker 1: universe with a preferred direction and how that might manifest itself.
41:03
Speaker 1: And so the next step is to like come up
41:05
Speaker 1: with an explanation that could link all these things together
41:08
Speaker 1: and then figure out a way to test that. You know,
41:10
Speaker 1: before you get there, you gotta like really make sure
41:13
Speaker 1: that these things are real. So we've done a lot
41:15
Speaker 1: of careful studies, like make sure these aren't like an
41:17
Speaker 1: artifact or some problem with the data processing. You know,
41:21
Speaker 1: that it really is real. But a lot of these
41:23
Speaker 1: things have been confirmed independently by like several different satellites,
41:26
Speaker 1: especially the CMB and issotropy. All right, so what are
41:29
Speaker 1: some of the possibilities about what could be going on? Well,
41:31
Speaker 1: I had a hard time finding anything that was really
41:34
Speaker 1: very credible. The only idea I could find that really
41:36
Speaker 1: wasn't immediately dismissible was the idea that there could be
41:39
Speaker 1: some like giant cloud of matter outside the observable universe.
41:44
Speaker 1: You know, we think maybe the universe is infinite. We
41:46
Speaker 1: can see a piece of it, but there should be
41:49
Speaker 1: parts of the universe beyond the things that we can see,
41:52
Speaker 1: And in principle, those could be affecting things in our universe.
41:56
Speaker 1: Like the things outside the observable universe we can't directly see,
41:59
Speaker 1: but things in our observe universe could see them. They
42:03
Speaker 1: could be influenced by them gravitationally. So now imagine some
42:06
Speaker 1: like crazy collection of stuff on the outside of the
42:09
Speaker 1: observa universe that's like distorting what's happening inside the observa universe.
42:15
Speaker 1: It's ridiculous, and we require like incredible cosmic structures and
42:19
Speaker 1: gravitational effects, but it's sort of the only plausible direction
42:23
Speaker 1: to explain this interesting alright, So maybe there's a giant
42:27
Speaker 1: I don't know, kangaroo space kangaroo which is outside of
42:30
Speaker 1: our field division that is somehow skewing the whole universe.
42:34
Speaker 1: What else could be going on? It could also just
42:36
Speaker 1: be random, you know, it's very difficult to know what
42:38
Speaker 1: the chances of this are happening. In physics, whenever we
42:41
Speaker 1: want to conclude that something is real, we need to
42:43
Speaker 1: know what are the chances that this could have just
42:45
Speaker 1: happened by a random you know, eventually, if you flip
42:48
Speaker 1: enough coins you will see weird deviation. So we want
42:50
Speaker 1: to not conclude something deep and true about the universe
42:53
Speaker 1: if it just happens to be a strange fluctuation. In
42:56
Speaker 1: this case, it's very difficult to evaluate that because we
42:58
Speaker 1: didn't set out try to measure this. We sort of
43:01
Speaker 1: noticed it after the fact, and it's easy to notice
43:04
Speaker 1: coincidences after the fact. That it's hard to account for
43:07
Speaker 1: all the coincidences you didn't notice and sort of really
43:10
Speaker 1: like measure what the chances are of this happening. You
43:14
Speaker 1: need to imagine, like what are all the other things
43:16
Speaker 1: you might have seen and noticed? And and that's impossible.
43:19
Speaker 1: For example, somebody went through the CNB spectrum and they
43:22
Speaker 1: found that the initials of Stephen Hawking can be read
43:26
Speaker 1: in the cosmic microwave background radiation. What he graffitied the
43:30
Speaker 1: beginning of the universe. It's ridiculous, but there is a
43:33
Speaker 1: patch in the CNB which, if you're looking for it
43:36
Speaker 1: spells out the letters S and H. You know, what
43:38
Speaker 1: are the chances of that? For example? Well, you know
43:41
Speaker 1: who can know, because you know who knows what other
43:44
Speaker 1: things you would have looked for in the constate microwave
43:47
Speaker 1: background radiation. Yeah, that could be a coincidence. But then
43:49
Speaker 1: the other part of it is the part that says
43:51
Speaker 1: was here that's harder takes plain there was here's a joke,
43:56
Speaker 1: the S n H really is there, Like you can
43:58
Speaker 1: go in the foro it. This is not something I'm
44:00
Speaker 1: making up. It's just an example of how things that
44:03
Speaker 1: seem totally implausible really can just be random. Because it's
44:06
Speaker 1: very hard to measure the chances of something happening also
44:10
Speaker 1: depends on your point of view, Like if you look
44:11
Speaker 1: at it upside down, it says HS. So maybe it
44:15
Speaker 1: was really Harry Styles who graffiti the beginning of the universe.
44:18
Speaker 1: That guy seems eternal, you know, and he's pissed that
44:20
Speaker 1: Stephen Hockey is getting all of his press. Or maybe
44:24
Speaker 1: it's all a big joke, the same person Harry Styles is.
44:28
Speaker 1: But you know, to really answer this question, you need
44:30
Speaker 1: to either develop a theory which explains these coincidences and
44:34
Speaker 1: make some prediction we could test, or you know, you
44:37
Speaker 1: need to build like another CNB telescope and teleported to
44:41
Speaker 1: other parts of the universe to see if it measures
44:43
Speaker 1: the same thing somewhere else. Because really the question we're
44:46
Speaker 1: asking is are we in a privileged location? Is what
44:49
Speaker 1: we're seeing weird? And the most direct way to answer
44:51
Speaker 1: that is to go to other parts of the universe
44:53
Speaker 1: and to make these measurements there. That's of course totally impractical,
44:57
Speaker 1: but that would sort of like really deeply answer the question,
45:00
Speaker 1: right or I wonder if it could be there also
45:02
Speaker 1: that the universe doesn't have a preferred direction, but somehow
45:04
Speaker 1: the matter and the way it formed in the universe
45:07
Speaker 1: that we are living in. Maybe somehow it started spinning
45:11
Speaker 1: in one direction, just like our Solar system randomly picked
45:13
Speaker 1: the direction to be spinning it. Yeah, although if the
45:16
Speaker 1: universe is infinite, then we would expect all those things
45:19
Speaker 1: to average out. Right that you do have clumpiness here,
45:22
Speaker 1: and you do have rotation there, but on average things
45:24
Speaker 1: should be even. And the kind of things we're measuring,
45:26
Speaker 1: you know, the spinning of galaxies across these huge distances,
45:30
Speaker 1: we do expect things to average out on those distances.
45:33
Speaker 1: They don't average out on the Solar system distance or
45:35
Speaker 1: the galaxy distance, but you know, across huge superclusters, they
45:39
Speaker 1: really should average out. All right. Well, I think there's
45:42
Speaker 1: all just kind of points to how interesting it is
45:44
Speaker 1: that we're trying to decode the entire universe from this
45:47
Speaker 1: one little spot in the corner that we're sitting on.
45:50
Speaker 1: You know. It's like, you know, we're sticking our finger
45:52
Speaker 1: out trying to measure the wind of the universe, and
45:54
Speaker 1: but really we're just like confined to this one spot
45:57
Speaker 1: where we are. Yeah, And it also gives you a
45:59
Speaker 1: glimpse into sort of the process of physics. When you
46:02
Speaker 1: look back on the history of physics, it seems sort
46:04
Speaker 1: of like inevitable, like we found this, then we figured
46:06
Speaker 1: that out, then we figured this other thing out. But
46:08
Speaker 1: at any moment we're really just clueless. When we're exploring
46:10
Speaker 1: lots of different paths, some of which are totally bonkers
46:13
Speaker 1: and some of which could be the seeds of a
46:16
Speaker 1: future understanding. People could look back on these moments be like, oh, yeah,
46:20
Speaker 1: people first found out about this crazy thing in the
46:22
Speaker 1: universe back then, and people didn't really believe it for
46:25
Speaker 1: a long time, and it took forever to take hold.
46:28
Speaker 1: That could be this idea right now, or this could
46:30
Speaker 1: just be another in the long series of science dead ends,
46:34
Speaker 1: I guess. In the meantime, if you're in Australia, watch
46:36
Speaker 1: your step, don't fall off, and don't flush the toilet
46:39
Speaker 1: at the same time. That's right, keep spinning everyone, All right, Well,
46:42
Speaker 1: we hope you enjoyed that. Thanks for joining us, See
46:45
Speaker 1: you next time. Thanks for listening, and remember that Daniel
46:55
Speaker 1: and Jorge explained the Universe is a production of I
46:58
Speaker 1: Heart Radio. For more podcast from my Heart Radio, visit
47:02
Speaker 1: the i heart Radio app, Apple Podcasts, or wherever you
47:05
Speaker 1: listen to your favorite shows. H