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

Episode Date: February 15, 2022

Daniel and Jorge talk about the hypothesis that there is a cosmological Axis of Evil Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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Learn how to get comfortable pivoting because your life is going to be full of them. Listen to these women and more on She Pivots. Now on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Hey Daniel, what's one of the hardest physics questions someone's ever asked you? Oh, well, someone asked me once, if the earth is round, why don't people fall off the bottom of it? That is a pretty good question, yeah. I think we got that one on live radio once, didn't we? Yeah, we did, exactly.

No preparation. But why is that a hard question? Well, the hard part is figuring out why that question makes sense to the person asking it. You mean, like, how does gravity even work? Yeah, you have to know like what they are misunderstanding so that you can find a path to get them some actual understanding. So what's the answer? Why don't people just, you know, fall off Australia? How do you know they don't? I mean, have you been to Australia? Maybe the whole thing's a hoax. You mean Australia is a hoax? Or gravity's a hoax? Which one? Kangaroos don't really exist?

I think my lawyers would advise me not to answer any of those questions. Hi, I'm Horham, a cartoonist, and the creator of Ph.D. Comics. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I have never been to Australia or New Zealand. Really? You've never been down there? Planned it many times, never actually happened. How about you? You've been to Australia. I think I've seen a picture of you talking to kangaroo. Yeah, yeah, they're very chatty if you can get them to sit still. That's amazing.

Australia's awesome. I mean, it's like going to another continent, literally, but it's really like going to another world. Like all the plants are different. They're bigger. The animals are bigger. They're different. It's pretty amazing.

Definitely on my to do list. Yeah, but welcome to our podcast, Daniel and Jorge, Explain the Universe, a production of IHeartRadio. In which we explore all the continents of modern physics, the weird, the strange, the ones that we understand, the ones that are unfamiliar, the ones that seem weird and the ones that might bite you in the night.

We talk about all the biggest questions in the universe from the scope of the whole shebang, how it started, where it came from, how big is it? How does it all work? Where is it going? All of these questions, we talk about them without fear, without shame, and without hesitation. And we explain all of them to you. Yeah, because physics bites is what you're saying, I think. Sometimes you get an understanding of a problem that can really sting.

Yeah, but it is pretty cool Australia to think about Australia, If you think about it, they sort of see a whole different side of the space than we do here in North America. Yeah, and you are used to thinking about the solar system with the Earth on the sort of top side of it. But that's sort of North Hemisphere-centric. If you're on the Southern Hemisphere, then that half of the solar system is sort of looking out and up into the universe just as much as we are. Yeah, and we have a lot of listeners in Australia. Do you think they listen to it upside down or it's sort of weird to think that they're listening to this upside down from us right now? They are, exactly. In Australia, you're the physicist and I'm the cartoonist.

That's right. You're the funny one and I'm the not so funny. You can grow a goatee in Australia and I can't. Yeah, it is a pretty interesting universe and it's a 360 universe. It's all around us in all directions where we look from anywhere on Earth, but it's sort of interesting to think about directions in space. It is. And for a long time, humans have sort of imagined that the Earth is at the center of the cosmos, that we look at the universe in every direction, but that we are sort of in a special location. And it wasn't until about 500 years ago with Copernicus that we started to realize, hold on

a second, maybe there is no special location in space. Maybe we're just at some random point. And that gives you a completely different view about the shape and the nature of the universe that we are seeing. Yeah, it was weird for humans to think that we are not the center of the universe, although I am sort of the center of my universe. Or wait, maybe I should correct. My kids and my spouse are the center of my universe, of course.

I think there's an emotional moment there also when kids grow up and realize that they are not the center of everything, that the whole universe doesn't revolve around them, that other people are people too. Yep, unless your kids are aliens, in which case you might have a more interesting realization. And it's kind of hard to understand what a big mental shift that was, you know, something that we now are very comfortable understanding that we are just in a random spot in the universe. But it was a huge conceptual shift, the kind that I don't think we can even really ever understand because we weren't firmly rooted in the other idea that we are special at the center of the universe. But giving up a long held assumption about the nature of the universe, that's sort of the joy of physics. You know, that's when physics

stings when it like tells you, oops, you've been thinking about things completely the wrong way. The universe is fundamentally really different from the way you imagined it. I long for that kind of cosmic realignment. When it crawls up your pants and bites you in the behind, that's what you look forward to. He's enjoying that, Steve, yes. But, yeah, at some point, humans realize we're not in any kind of special point in space, you know, and it sort of informs everything, right? It informs the theories, sort of the equations about physics.

It has to do with symmetry and all that. So there's no specific or special point. We don't even know if we're at the center of the universe or like in a corner of the universe or we don't even know if it makes sense in an infinite universe to have a point, right? Yeah, and the joke you made earlier is actually true. you are at the center of your observable universe. You know, we don't know how big the universe is. We can only see a portion of it, and that portion is limited by the speed of light.

And so the part of the universe that you can see is the part where light has had time to get to you since the beginning of the universe. And that's actually a different if you're in our sun and if you're at another sun, because you can see a different portion of the universe because light that has reached, you know, Alpha Centauri may not have come yet to our sun. And that's also true for my head and your head. So technically speaking, we are the centers of our own observable universes. And so the universe doesn't seem to have any kind of preference for any particular point in space,

but there's sort of a bigger question about whether it has a special direction in space that it likes. Yeah, they're connected questions, but they actually are separate. One is connected to the question of, are the laws of physics the same everywhere in the universe? You know, if you do an experiment here, does it matter? Would you get a different answer if you do it somewhere else or if you do it in another star system? Are alien physicists measuring the same law of physics? We're pretty sure that they are. But there's another question, which is, does the universe have a preferred direction, right?

Like, if you rotate your experiment, could you possibly get a different answer? Could you measure some preferred direction of the universe? Like, is there an up or down in the universe, kind of, or left or right? Yeah, or like a special direction around which the universe prefers or something, like an Axis. All right. So today on the podcast, we'll be asking the question. Does the universe have a preferred direction?

Now, I assume this is like a spatial direction, not like an emotional direction or an acting direction. Creative direction. Yeah. The universe prefers method actors. Yeah, you know, prefers comedies as opposed to dramas. What's the tone of the universe, Daniel? Maybe it's a hoax. the whole universe is a hoax no and that's why this is a physics podcast and not a Hollywood industry

podcast we're not talking about the latest trends in you know representation in Hollywood movies or anything we're talking about directions in space you know if the universe had some specific direction that was different from the other ones then in principle you might be able to measure that you could like design an experiment that would be sensitive to it the way for example the surface of the earth does have preferred directions or different directions right there is a on the earth and a south on the earth. And you can design an experiment. It's called a compass to measure it, to detect it, and to use that to navigate.

Or like if you're on Earth, there's sort of an up and down, right? I mean, it depends on where you are on Earth, but there's sort of like a towards the center of the Earth or away from the center of the Earth. Is that kind of, would that also count as a direction? Absolutely. Yeah. Gravity defines a direction on the surface of the Earth. Absolutely.

And as you say, it's towards the center, which is actually the answer to the question. Why don't people fall off Australia? I'm sure people fall in Australia, but do they fall off of Australia? I don't think they trip and then fly off into space. I think we would have seen that on YouTube if that was happening. Maybe you have a rocket-powered, you know, parachute or something. Right. And the answer is intuitive and obvious to everybody who understands the Earth is a sphere,

but obviously down is towards the center of the Earth, which is why people fall down towards the center of the Earth everywhere they are on the planet. And you're right, like the direction there is relative to the center of the Earth. But that's just arbitrary, right? you could pick anything. But the question is, you know, is there a non-arbitrary choice? Is there a direction which makes sense no matter where you are in the universe?

Well, you just made me think that, you know, we feel gravity towards the center of the Earth, but we're also being attracted by the Sun a lot, right? So does that mean that our gravitational vector or the right kind of gravity is sort of always slightly tweaked towards the Sun? Yeah, absolutely. The gravity of everything is affecting how much you weigh. And so as the Earth rotates, you're right. weight changes a very small amount but you know the amount that the sun pulls on you versus the earth

pulls on you is very small so at noon is when i'm lightest right technically is when i weigh less that's right at noon the sun is pulling you off of the earth and at midnight the sun is helping the earth pull you towards its center so you gain weight at night so this is the travel the earths are always at noon diet that's right that this is why i eat a big lunch because i can right that's right every meal is lunch the Jorge physics diet. I avoid meals at midnight, although sometimes you can't help it. I've been traveling with you.

I know you eat meals at midnight, dude. I ate at midnight at 1 a.m., 2 a.m. I have no preferred time for directing my meals. So I guess the question is, the Earth has a preferred sort of gravitational direction, but you're saying like does the universe have, maybe not a gravitational direction, but just like, you know, a different direction

or some sort of different effect that changes depending on which way you're pointing in out there in space. Yeah, and really sort of the cleanest way to define this is imagine getting transported to an arbitrary location in the universe. Could you build an apparatus which could measure some location so that if you're transported to some other location and randomly rotated, you could like tell how far you've been rotated. You could measure it.

And, you know, like on the surface of the earth, you can tell your direction because you could just use the magnet. But, you know, that doesn't work obviously off. surface of the Earth. So can you build like a universal compass that always tells you, you know, a reference direction? And if the universe has no preferred direction, then that's impossible because there's no physical mechanism which prefers one direction over another. Right. That would help you sort of navigate the universe in a way, right? Like if you get lost in the universe, you could sort of look at your cosmological compass and be like, oh, I need to go, you know, east or whatever in space and I might

reach Earth again. It certainly would help you navigate, but it would also like blow up our idea of how the universe works. Right now, we really assume that the universe has no preferred direction and no preferred rotation. But recently, there have been some ideas that suggest that maybe there is a preferred direction. And these go by sort of a cosmically silly name. Yeah, because we've been assuming that if there is a special direction, it would be the

universe's preferred direction. But what if there's a direction that the universe does not like? Like, what if it's the opposite? What if it's like a least favorite direction in the universe? A cosmological axis of evil. Yeah, that's the sort of name that you have for in the physics community, right? The cosmological axis of evil. That's right.

There's been this idea bubbling up that maybe we were wrong in thinking that the universe has no preferred direction. Maybe it does. Or a non-preferred direction, right? I think the origin of the idea axis of evil is that it undermines our idea that the universe doesn't prefer anything. It's like nobody should be preferred. So the axis of evil is like spoiling an other. otherwise pristine and beautiful idea. Oh, I see.

But it is a phrase that people use in the physics community to like, oh, you're talking about the cosmological axis of evil. Oh, absolutely. Or C-A-E for short. Absolutely. There's a paper titled The Axis of Evil, which I just read yesterday. Like, this is not something I came up with or just a joke on podcasts. It's really a physics term for a deep concept.

I feel like you just used, I read it in a paper as in like that's supposed to, be an ultimate authority. It's like, I saw it on YouTube. It must be right. I saw it on Archive. It must be true. I don't know if the physics is sound or if it's actually right, but it is something people actually say in the physics community.

So there is that much. Cosmological axis of evil. That's what we'll dig into today. And so as usual, we were wondering how many people out there had heard of this cosmological axis of evil and whether they have any idea about what it means. So Daniel went out there into the internet to ask people this question. Here's what they had to say. On a guess, cosmological, something to do with very large scale structures in the universe.

Axis of evil, perhaps it's something to do with the way that certain fields are calculated and there's some weird mathematical structure that causes problems. I have no idea. I have no idea. I couldn't even begin to guess. Sounds familiar, but I don't know what it is. Probably I'm watching too much TV. I can tell you right off the bat, I'm stealing that,

and that is going to be the name for my new punk rock band. But aside from that, I have no clue. My only guess is that that is what we would call the things that are going to be responsible for the end of the universe. So maybe dark energy and entropy are the cosmological axis of evil. The cosmological axis of evil is the nexus in the universe where everything that is evil intersects. Think the dark side of the force.

Live, because evil backwards is live. What does that have to do with the axis of evil? I guess that's a good enough answer, because I have no idea either. So I'll go with, it's something with the Boatase void and the great attractor, and the void is somehow funneling all of the matter from the universe into the great attractor to create a super giant black hole that's going to swallow everything. How's that sound? That's an axis of evil.

mustache twirling enemies in there or I guess goate Jorge because he was in one of those parallel universe episodes before so I have no idea what the cosmological axis of evil is somehow I see Austin Powers and battling the cosmological axis of evil in my brain when I read this question I don't know anything beyond that all right nobody has any idea then It has not broken out of the physics community out into the larger population. And that's our job is to funnel the craziest, funnest, most interesting, wackiest ideas that are poorly named out into the larger community. Yeah, so you call an axis of evil, because I guess an axis is sort of like a direction. And you're saying that maybe this direction is sort of evil in the sense that it sort of ruins the universe or ruins your sort of perfect symmetry, a picture of the universe.

Yeah, I think that's right. Although historically and sort of philosophically, it's fascinating because I think, you know, the idea that the universe doesn't have a preferred direction went up against a lot of theological friction, you know, 500 years ago because people preferred the concept, you know, that the Earth was at the center of the universe and in a special location and sort of at the heart of the cosmos. So the idea that the universe didn't have a preferred direction was sort of seen as evil 500 years ago. and now doubting that idea is again seen as evil. So in that sense, maybe evil is just like, you know, the upstart. Well, I think if there's anything movies has taught us is that evil is a relative constant, you know, maybe not the Marvel movies, but, you know, more artful movies. Yeah, I think it's a pretty ridiculous name. You mean like in religious times or in a religious sense, like you want the universe who have a preferred direction?

You know, you want your deity to have some sort of point of view? Well, I think the Catholic Church, for example, was not a big fan of the idea that the Earth was not at the center of the cosmos. Galileo spent a long time under house arrest for insisting that it was. And I don't think that Copernicus was like number one favorite person by the Pope either. So I think that, you know, scientists got a lot of flack several hundred years ago for suggesting that the Earth was not at the center of the cosmos. But now there's maybe an inkling or a suggestion that maybe the universe does have a special axis, a special direction it likes. And so break it down for us. What does that mean and where does that come from?

So we've been operating under this assumption for a long time now that we don't have a special place in the universe, that there is no special place, that there is no preferred direction. And this really has grown out of like the Copernican principle from 500 years ago. And these days we call it the cosmological principle because we say it even more broadly.

We say that the whole universe is homogenous, is isotropic. That on a large scale, everywhere in the universe is basically the same. There's no center. There's no edge. there's no place that's different from any other place. And so if you spotted a deviation from that, if you detected something which seemed to prefer a direction, that would spoil something really deeply fundamental

at the heart of basically all of modern cosmology. Are those two things tied together, you know, like a special or preferred location and a preferred direction? Or are those, you know, independent? Like, can you have a preferred direction without a preferred location? Those are independent. They're in the same family of ideas, but there are actually two separate things.

And, you know, it really is interesting. The idea that the universe has no preferred location is a symmetry, right? It says you do an experiment here, you do an experiment there, you get the same answer. Space is the same here and there. That leads to a conservation law. We talked about it once in the podcast. Emmy Nuthers theorems tells you that every symmetry gives a conservation law. And in the case of having no preferred location, that's why momentum is conserved.

And in the case of rotation, the idea that if you rotate the universe, you should always get the same answers to your experiments. That's what gives you conservation of angular momentum. So there are two separate ideas, but they are closely connected, right? They're both connected to momentum. But I guess when did people start questioning whether there was a preferred direction? Because I've never heard of this idea that it could have a preferred direction, right? It comes out of some observations that have been made in the last few years. People have been assuming that things are equally smooth and the same in every direction.

But recently there's been this sort of like strange, unexplained alignment of various measurements that should be random. And when you see a bunch of coincidences line up, you start to wonder like, hmm, are these coincidences or are these sort of like the first clues into a new way to look at the universe? Interesting.

So this is based on some experimental results. Yeah. These are unexplained coincidences that have people starting to wonder if the universe might actually have a preferred direction. Well, you make it seem like a conspiracy or like a sort of secret, secret undercurrent,

some dark underbelly kangaroo pouch of the universe. Exactly, like some axes of evil, hatching some plan to spoil our view of cosmology. A bunch of Australians thinking about how to keep from falling out to Earth. Yeah, and I think it's worth exploring for a moment what this principle that we're doubting means, the idea that the universe is the same everywhere, because obviously it's not exactly the same everywhere. Like, you know, there's a star here and it's not a star there. There's a galaxy over here, but it's not a galaxy over there. It's not true that every place in the universe is exactly identical. It's a statement we make about very, very large scales.

Like if you really zoom out, out past galaxies and past galaxy clusters, out to galaxy's super clusters. And you look at sort of like the filaments and the foam of the largest scale structure of the universe, things should be about the same everywhere. It just made me think, like, is it possible to go out there into space and measure gravity?

And whether or not gravity kind of pulls you in one particular direction, would that tell you if you're at the edge of a universe, a finite universe or not? Yeah, and that would be a deviation. right? And so on the very largest scales, you should basically feel no effective gravity because there should be an even distribution of stuff in every direction. Pick a random place in the universe and there should be, you know, like super clusters over there and super clusters over here. And in the end,

it should all roughly balance. Of course, if you land near a black hole, you're going to feel some gravity. But on average, there should be, you know, effective tugging. And that comes from, you know, we think the universe was created smoothly and created homogeneously. And, you know, the variations that we do see the fact that there's a galaxy here and not a galaxy there, those come from the little perturbations, the little fluctuations in that smooth beginning of the universe. I see. All right. So there's some experimental measurements that tell us that maybe things are not homogeneous,

that maybe things do have a preferred direction. So let's get into this secret result. But first, let's take a quick break. LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass.

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Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy?

That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age. it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend

really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the Iheart radio app, Apple Podcasts, or wherever you get your podcast. I don't write songs. God write songs. I take dictation.

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wait, what? Oh, that's the run right. I'm looking at this thing. Listen to no such thing on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. We are determining whether the universe has a specific direction it likes or dislikes or I guess we're asking whether the universe leans a certain way, Daniel, right?

Or what's the universe's orientation? That's right. Is it a chocolate universe? Is it a vanilla universe? I was going to say, you know, bananas or pears. Is it Marvel or is it DC, right? Yeah. And that would determine whether I like the universe or not.

Although both of those universes have villains in it, right? Which do you think actually has more? which is the darker universe. Oh, for sure. DC, yeah. In the Marvel universe, people are more three-dimensional, I think. Evil has more dimensions to it. There's certainly more ridiculous jokes in the Marvel universe.

All right, so we were talking about how maybe there is some sort of result or some sort of experimental observation that maybe doesn't look like it's random and maybe hints that maybe there could be a special direction in the universe. Yeah, and there are actually several of these measurements, which together are very suggestive because they all sort of line up to seem to prefer one direction. And the first one comes from information which should be very familiar to listeners of the podcast. It's the cosmic microwave background radiation. This is light that comes from the very, very early universe.

Remember when the universe started, it was very hot and very dense, but it was also very opaque. It was sort of like the center of the sun. When things are really hot and nasty, then light gets absorbed by other molecules as soon as it's made. But then the universe expanded and it cooled. And at some moment, around 380,000 years after the Big Bang, it cooled. enough to become transparent. And so the cosmic microwave background radiation are those photons that were created at that moment, the first moment the universe was transparent and are still flying around

the universe today. Yeah, like if you point your antenna anywhere in space, you sort of get a hum, right? You get a little, like a static hiss that it actually turns out to be from the Big Bang. Yeah. And the universe was super duper hot back then. It was like 3,000 degrees Kelvin. But in the 14 billion years that those photons have been flying around, the universe is expanded. And so they've been sort of red shifted. They've been pulled into longer wavelengths,

which we then translate into a temperature. And so the temperature of the CMB is around 2.7 Kelvin. And so it's very, very long wavelengths, which is why like you can't see the CMB with your eyes. You need a special antenna. And it was discovered, you know, several decades ago, we have a whole episode about it. And it was a really nice piece of evidence that the universe was at one point a very hot and dense plasma. But it's not like a perfectly smooth picture. It is kind of like bumping. and lumpy and it has a certain texture to it. If you point your antenna in one in some directions, it does sort of the sky feels hotter than other spots.

Yeah, and it's a great way to visualize what we mean by the universe being like smooth and isotropic. Because if you look at the CMB, there are variations in it. There's little spots that are hotter and little spots that are colder. But that doesn't mean there's any preferred direction. It just means that there are some random quantum fluctuations in the early universe over this smooth background. And those fluctuations are exactly what led to, you know, like a galaxy

forming here or a super cluster forming over there. These were like the seeds of structure of the later universe. And so we study this in great detail to understand exactly how the universe formed. And those seeds of structure really controlled the rest of the evolution of the universe. So it's super interesting to look at that. And that's one of the scale in which we study the universe to understand whether it's smooth. We like take a big chunk of the CMB and say, is this on average the same as another big chunk of the CMB? So mostly it's very smooth.

But you're right, there are these very. like one part in 100,000 where spots are a little hotter or a little colder. Right. If you sort of look at a picture of it, it sort of looks like a camouflage pattern almost in a way, right? Like it's sort of blobby and it has these kind of texture to it. And that's when that has been exaggerated, right? If you just looked at a plot of CMB on a normal scale, it would look perfectly smooth. It's only when you like really zoom in or you exaggerate these fluctuations that you can even see them. And we've been sending satellites up into the sky to sample it for decades and that.

And we started out with like a very fuzzy picture of it, and then a clear and crisper and crisper. And now we could see it like with really high resolution and great accuracy, we can measure all these ripples. And it allows for incredible studies of the nature of the universe. The shapes of those fluctuations tell us about like how much dark matter there was back then in the early universe and how much dark energy there was and how the universe has expanded since then. It's an incredible treasure trove of information about how the universe looked back then at the very beginning and how it's evolved in the meantime. Yeah, and so it's sort of

textured like a camouflage pattern which sort of varies locally in like a small spot, but if you sort of step away from the camouflage pattern, it all sort of generally looks the same or it looks sort of homogeneously kind of textured. But I guess here you're saying that maybe there's a larger

asymmetry to it. Like maybe some areas of the sky are differently textured than other areas of the sky. That's right. It turns out there is a little bit of an asymmetry. If you look at top half of the sky that is the part of the universe that's like above the plane of the solar system, it turns out to be a tiny little bit colder. Those photons have a wavelength that's a little bit longer. And if you look down sort of the bottom half of the solar system, then that portion

of the sky is a little bit hotter. Those photons are a little bit bluer. Well, that makes sense, right? Australia is a little bit hotter in general. It's so hot, it's heating the entire universe. I'm just kidding. But wait, when you say like the top half and the bottom half, do you mean like the north? Like if you look in the northern hemisphere of the sky or do you mean like some other direction? I mean roughly the north, but I'm talking about relative to the solar system. So the sun has a north pole and a south pole and the planets orbit around the sun in a plane that's perpendicular to the sun's north pole and south pole. I mean like the disk that where all the planets are spinning, it sort of forms a like a plate.

Yeah, it forms a plate. and the sun's north pole, south pole goes like straight up and down through that plate. And the earth moves along that plane, we call it the ecliptic. The earth is a little bit tilted, so the Earth's north and the sun's north are not quite aligned. But when we study these things about the universe, we try to orient ourselves relative to the sun or to the center of the galaxy rather than to the earth. Turns out that the cosmic microwave background radiation in the sun's northern hemisphere, that is the portion of the universe that's like above the plane of the solar system,

is a little bit colder than the rest of the universe below the solar system. Interesting. And so we're sure it's not like an error in measurement. Like maybe they're using different units done in Australia or Argentina where they're measuring this. No, it's definitely a real thing. It's super fascinating. And there's two things to understand about it. One is like, what does it mean?

And the other is, what does it mean that it's oriented with the plane of the solar system? Like, it's not necessarily a huge surprise that there is an asymmetry because we can interpret this as, the Earth or the solar system, at least, moving through the cosmic microwave background radiation. Like the universe doesn't have to have a preferred location or preferred direction or velocity. But the stuff in the universe, that plasma that made that light 14 billion years ago, it was somewhere. It had a location. It had a rest frame, a place where you could say, okay, I'm at rest relative to that plasma. And so then you can say, well, you can be at rest relative to this cosmic microwave background radiation. And it turns out that we are

sort of moving through that radiation, which red shifts some of it and blue shifts other parts of it. Right. It's almost like if you were running really fast towards a flashlight being pointed at you, you would see the light slightly, not perfectly white, but a slightly different color. And if someone was pointing a flashlight at you running away, you would also, when you look back, see that light slightly shifted in color. Yeah. And so it's nice to think about the cosmic microwave background radiation as sort of a cosmic rest frame, something against which you can measure your velocity. That doesn't mean the universe has a rest frame, right? It's just like these things do exist. They are out there. They're shining lights at us. And so you can measure these Doppler

shifts, as you said, these red shifting and blue shifting. And so we are moving through the CMB at like 370 kilometers per second. Yeah, it's almost like there are flashlights pointed at it is from every direction. That's kind of the CNB, right? And so if we're moving and then we're going to see some of those flashlights a different color than the ones, for example, behind us. Yeah, and I think it's a point of confusion here. A lot of people writing and asking, like, why is it we can see the CNB right now and not earlier or not later? And I think the conceptual idea here to unpack is that the CNB was everywhere.

This plasma filled the whole universe and generated light in every direction. What we are seeing now is just the portion of it, which happens to be arriving right now. So as you said, imagine people shining flashlights 14 billion years ago in every direction, which flashlights would we see right now? We'd see like a shell of flashlights that are super far away from us that happen to arrive right now. As time goes on, we see a different slice of the CMB.

So we don't see the whole CMB. We see sort of like a spherical shell of it at any moment. All right. So us moving through this radiation, this light would explain why it feels cooler and hotter on one side of the solar system, North Pole or not. But that doesn't mean that the universe has a preferred direction.

It just means we're moving through it in a certain direction. That's right. The weird thing is that it's aligned with the plane of our solar system. Like, why is that? The CMB having some rest frame and us moving through it, no big deal. Why are we moving through it exactly aligned with the plane of our solar system? Because our solar system, you know, has no connection to the CMB. It just is what it is. It's not even that well aligned with the plane of our galaxy, which is not well aligned with the CMB.

So it's a little bit odd. It's like strange, maybe a coincidence. maybe not, that the plane of our solar system is aligned with this other cosmic plane. Well, if it's not a coincidence, what else could it be? Well, that's the question. Like, if it's not coincidence, it needs to have some explanation. There needs to be some mechanism that says, like, all right, the universe has a preferred direction, which causes both of these things to line up in this direction.

If you didn't know what a compass was and you saw two compasses and they're like, oh, look, the red arrows are both pointing in the same direction. I wonder why. And you've got to dig deeper and find some, like, mechanism that explains. means what aligns those two in the same direction. And so we're just the beginning of like understanding what that might be. You know, large scale gravitational effects on the outside of our observable universe could like distort the whole universe in a way that makes things aligned in this way, for example.

Oh, I think I see what you're saying. You're saying that the fact that we see the CMB colder in one direction and harder in another direction is not evidence that the universe is somehow biased. It's the coincidence that our solar system is aligned to the, this direction. That's the weird thing. Like maybe whatever caused us to be moving in that direction and whatever caused our solar system to be pointed in that direction, maybe it's somehow related. Yes. And it's a little weird and you might just brush it off and say like, oh, it's just coincidence, whatever. They both have to have a direction. But there are other things aligned with our

solar system that have been like slowly piling up the coincidences enough that people are like, hmm, maybe this is a thing. All right. Yeah. So what are those things? Well, a second one also relates to the CMB because people were wondering, like, are we moving relative to the CMB or is the whole universe moving relative to the CMB? Like, is the entire current existing stuff in the universe? Is that at rest with respect to the CMB? So people tried to make another measurement of our velocity independent of the CMB. They tried to measure the Earth or the solar system's velocity relative to the whole universe of stuff that exists right now. You mean the stuff that we can see? The stuff that we can see, yes. And so instead of

using the CMB, they're like, let's look at the stuff that exist right now, the stuff we can see. So what they did is they looked at a bunch of quasars. These are very energetic black holes at the hearts of galaxies. And black holes, of course, are themselves dark, but these black holes are so powerful. They have millions or billions of times the mass of the sun that they create incredible radiation around them because of the tidal forces causing friction and the gases that are falling into the black holes. So these are some of the brightest things in the universe, which is really helpful because then you can see a lot of them and you can see them really far away and you can see a distortion in them because if they're like shifted in one frequency or shifted in another

frequency you can use that to measure our velocity relative to these quasars so people ask this question they're like are we moving relative to like all the quasars that we can see out there in the universe i see it's trying to get a sense of like in the observable universe are we moving left or right and what they found is that we are moving relative to those quasars we're moving around 600 kilometers per second relative to those quasars, which is a big surprise. First of all, people were like, what? Why are we moving so fast relative to like the average stuff in the universe? But when you say we're moving, do you mean like our solar system or our Milky Way or our

galaxy cluster? What do you mean? I mean our solar system. Okay. But don't we know how our solar system is moving relative to our, the Milky Way? Yeah, absolutely we do. All right. So you're saying that our galaxy itself is sort of moving through the observable universe?

Yeah, our galaxy seems to be moving through the observable universe. And the really surprising thing is that it seems to be moving relative to these quasars in the direction aligned with this CMB antisotropy. That is, it seems to be moving in the same direction along the sun's north and south pole. Well, that's a little weird, I guess, because, you know, like we're spinning on Earth and the Earth is spinning around the sun and the sun is spinning around the galaxy. And the galaxy, I imagine, is spinning around sort of the larger galaxy cluster. are you saying, I guess I'm not sure quite what you're saying. You're saying like all of those sort of velocity vectors, all of those directions of motion are somehow pointing in the same direction right now?

Wouldn't that change? Like, aren't we moving sometimes in this direction and that direction as we're going around the sun or the galaxy? Sure. The Earth is moving around the sun and the sun is moving around the center of the galaxy and the galaxy is orbiting the center of the galaxy cluster. And so each of those has a velocity and a direction relative to the CMU. Right now, we're talking about one of those in particular, which is just the velocity of the solar system.

And that velocity vector seems to point right towards the direction of the hotter part of the CMB. So that's really interesting. And it also seems to be aligned with the direction of those quasars. And there's no reason to think that these three directions should be aligned. They could have been anything. Now, the question of the Earth's velocity and the galaxy's velocity are separate, right? Those are different vectors. But the solar system velocity is aligned with the CMB and with those quasars.

Which is somehow aligned with the direction of the solar system. Is it also aligned with the direction of the Milky Way? Is our solar system disk in the disk of the Milky Way? It's not, right? Our solar system is actually tilted relative to the disk of the Milky Way. So this required just our solar system to somehow be weirdly aligned with this two cosmic axes, the CMB and the quasir. ours. It's a very strange coincidence. But I guess if we wait a few, you know, 100 years or

1,000 years, wouldn't our direction change because we're going around the galaxy? So our velocity relative to the galaxy does change as we move around the galaxy. The period of that is, you know, very, very long. It's millions and millions of years. But the direction of the solar system shouldn't change. Our conservation of angular momentum should mean that the, basically, the north and south pole of the sun shouldn't change, even as it moves around the center of the galaxy, the same way like the direction of the earth tilt doesn't change as it moves around the sun. I see. But you're saying then the Milky Way is moving in the same direction as our solar system is pointed at,

which is the same as what we measure with the C&B. The solar system is aligned with the direction of the C&B, but the Milky Way is a little bit tilted relative to the solar system. So it's not quite as aligned. And there's a third weird coincidence in the same direction. What is it? So people are constantly looking for things that are weirdly lined. And so what they did is they looked at these spins of galaxies.

You can look out deep into the universe and look at all these galaxies and you can measure which direction they're spinning in. Like a galaxy is like a little swirl and you can tell which direction it's spinning. Like is it spinning left or is it spinning right based on the direction that the arms are sort of trailing behind it? And you can look out and you can count like how many of them are clockwise and how many of them are anticlockwise. And you might expect if the universe is random and isotropic and no preferred directions for that to be like roughly even everywhere. Well, what they see is that there isn't asymmetry. And they see this asymmetry again aligned with the plane of the solar system. That galaxies you can see above the ecliptic are more clockwise.

And a galaxy you can see below the ecliptic tend to be more counterclockwise swirling. What? Wouldn't that be explained by the fact that, you know, like you're looking at the bottoms of some galaxies and you're looking at the tops of some galaxies depending on how you look at them? Yeah, but if they're randomly oriented, you should see the same number of clockwise and countercentric. clockwise. Like the same galaxy, if it's spinning in one direction, you'll see it clockwise or counterclockwise, depending on which side of it you are on. But if they're all in random places and all in random directions, you should see the same number in every direction. It's like if you

throw a million coins in a room, you should have the same number of heads and tails in every direction, right? But we see an asymmetry. We see like more heads over here and more tails over here, which is weird already. But that asymmetry is then aligned with these other asymmetries. We see the one in the CMB and the motion relative to the quasars. Interesting. You mean, it's sort of like the whole toilet flushing in the different direction in the southern hemisphere, right? Yeah. Although, I don't

know if that's really a thing. Yeah, I think it is a thing, right? Because we know that the hurricanes spin in different directions, right? They do spin in different directions because of the corollous force. You're absolutely right. But I don't know if that actually controls the direction in which toilets flush. So Australian listeners, let us know. But don't

all flush at the same time because you're going to drain the continent and drive. You'll slow the earth. spin if you all flush at the same time. All right. Well, so there's a lot of interesting coincidences that maybe tell you that the universe has a preferred direction. And so let's get into what this all means. But first, let's take a quick break. December 29th, 1975, LaGuardia Airport.

The holiday rush. Parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay.

Terrorism. Law and order, criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit.

Well, Dakota, it's back to school week on the, Okay Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy? That sounds totally inappropriate.

Well, according to this person, this is her boyfriend's former professor, and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I don't write songs. God write songs. I take dictation.

I didn't even know you've been a pastor for over 10 years. I think culture is any space that you live in that develops you. On a recent episode of Culture Raises Us podcast, I sat down with Warren Campbell, Grammy-winning producer, pastor, and music executive to talk about the beats, the business, and the the legacy behind some of the biggest names in gospel, R&B, and hip-hop. This is like watching Michael Jackson talk about Thurley before it happened. Was there a particular moment where you realize just how instrumental music culture was to shaping all of our global ecosystem? I was eight years old, and the Motown 25 special came on.

And all the great Motown artists, Marvin, Stevie Wonder, Temptations, Diana Ross. From Mary Mary to Jennifer Hudson, we get into the soul of the music and the first. purpose that drives it. Listen to Culture raises us on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Imagine that you're on an airplane and all of a sudden you hear this. Attention passengers. The pilot is having an emergency and we need someone, anyone to land this plane. Think you could do it? It turns out that nearly 50% of men think that they could land the plane with the help of air traffic control. And they're saying like, okay, pull this, Let's do this, pull that, turn this.

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Those who lack expertise lack the expertise they need to recognize that they lack expertise. And then, as we try the whole thing out for real. Wait, what? Oh, that's the run right. I'm looking at this thing. See? Listen to no such thing. on the IHeartRadio app,

Apple Podcasts, or wherever you get your podcasts. All right, Daniel, here's now our favorite question. What does it all mean, man? What does it mean that the universe has a preferred direction? I guess the theory is, the hypothesis, is that the universe has some sort of preferred direction that is somehow making galaxies all sort of spin roughly the same direction and it's making our solar system roughly spin in that direction

and everyone's moving in that direction. So what does that mean? We really don't know what it means. And mainstream cosmology is very certain that it's all just random, that it's fluctuations. They're very strong believers in the cosmological principle that the universe is the same everywhere and that there is no preferred direction. It would just be very difficult for them to give up this principle, which is precisely why it's so much fun to think about and to talk about because it's those kind of like huge mental revolutions that are the best moments in physics. And so what does it mean? It means that people should spend some time thinking about how it might be possible to have a universe with a preferred direction and how that might manifest itself. And so the next step is to

like come up with an explanation that could link all these things together and then figure out a way to test that. You know, before you get there, you got to like really make sure that these things are real. So we've done a lot of careful studies like make sure these aren't like an artifact or some problem with the data processing, you know, that it really is real. But a lot of these things have been confirmed independently by like several different satellites, especially the CMB and isotropy. All right. So what are some of the possibilities about what could be going on? Well, I had a hard time finding anything that was really very credible. The only idea I could find that really wasn't immediately dismissible was the idea that there could be some like giant cloud of matter

outside the observable universe. You know, we think maybe the universe is infinite. We can see a piece of it, but there should be parts of the universe beyond the things that we can see. And in principle, those could be affecting things in our universe. Like the things outside the observable universe, we can't directly see, but things in our observable universe could see them. They could be influenced by them gravitationally. So now imagine some like crazy collection of stuff on the outside of the observable universe that's like distorting what's happening inside the observable universe. It's ridiculous and it would require like incredible cosmic structures and gravitational effects, but it's sort of the only plausible direction to explain this.

Interesting. All right. So maybe there's a giant, I don't know, kangaroo, space kangaroo, which is outside of our field of vision that is somehow skewing the whole universe. What else could be going on? It could also just be random. You know, it's very difficult to know what the chances of this are happening. In physics, whenever we want to conclude that something is real, we need to know what are the

chances that this could have just happened by a random, you know, eventually if you flip enough coins, you will see weird deviation. So we want to not conclude something deep and true about the universe if it just happens to be a strange fluctuation. In this case, it's very difficult to evaluate that because we didn't set out trying to measure this. We sort of noticed it after the fact. And it's easy to notice coincidences after the fact. And it's hard to account for all the coincidences you didn't notice. And so to really like measure what the chances are of this happening, you need to imagine, like, what are all the other things you might have seen and noticed? And that's impossible. For example, somebody went through the C&B spectrum and they found

that the initials of Stephen Hawking can be read in the cosmic microwave background radiation. What? He graffated the beginning of the universe. It's ridiculous, but there is a patch in the CMB, which if you're looking for it, spells out the letters S and H. You know, what are the chances of that, for example? Well, you know, who can know? Because You know, who knows what other things you would have looked for in the cosmic microwave background radiation. Yeah, that could be a coincidence. But then the other part of it is the part that says, was here, that one's harder to explain. The was here is a joke.

The S&H really is there. Like, you can go and look for it. This is not something I'm making up. It's just an example of how things that seem totally implausible really can just be random because it's very hard to measure the chances of something happening. Also depends on your point of view. Like, if you look at it upside down, it says H. S. So maybe it was

really Harry Stiles who graffitied the beginning of the universe. That guy seems eternal, you know? And he's pissed that Stephen Hawking is getting all of his press. Or maybe it's all a big joke. Maybe they're the same person. Harry Stiles is Stephen Hawkins. But, you know, to really answer this question, you need to either

develop a theory which explains these coincidences and make some prediction we could test. Or, you know, you need to build like another C&B telescope and teleport it to other parts of the universe to see if it measures the same thing somewhere else. Because really the question we're asking is,

are we in a privileged location, is what we're seeing weird? And the most direct way to answer that is to go to other parts of the universe and to make these measurements there. That's, of course, totally impractical. But that would sort of like really deeply answer the question. Right. Or I wonder if it could be that also that the universe doesn't have a preferred direction, but somehow the matter and the way it formed in the universe that we are living in,

maybe somehow it started spinning in one direction, just like our solar system randomly picked the direction to be spinning it. Yeah. Although if the universe is infinite, then we would expect all those things to average out, right? You do have clumpiness here and you do have rotation there, but on average, things should be even. And the kind of things we're measuring, you know, the spinning of galaxies across these huge distances, we do expect things to average out on those distances.

They don't average out on the solar system distance or the galaxy distance, but you know, across huge superclusters, they really should average out. All right. Well, I think this all just kind of points to how interesting it is that we're trying to decode the entire universe from this one little spot in the corner that we're sitting on. You know, it's like, you know, we're stinging our finger out, trying to measure the wind of the universe. But really, we're just, like, confined to this one spot where we are.

Yeah, and it also gives you a glimpse into sort of the process of physics. When you look back on the history of physics, it seems sort of like inevitable. Like, we found this, then we figured that out, then we figured this. other thing out, but at any moment, we're really just clueless when we're exploring lots of different paths, some of which are totally bonkers, and some of which could be the seeds of a future understanding. People could look back on these moments to be like, oh yeah, people first found out about this crazy thing in the universe back then, and people didn't really believe it for a long time, and it took forever to take hold. That could be this idea right now, or this

could just be another in the long series of science dead ends. I guess in the meantime, if you're in Australia, watch your step. Don't fall off and don't flush the toilet at the same time. That's right. Keep spinning, everyone. All right. Well, we hope you enjoyed that. Thanks for joining us. See you next time.

Thanks for listening. And remember that Daniel and Jorge Explain the Universe is a production of IHeartRadio. For more podcasts from IHeart Radio, visit the IHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. December 29th, LaGuardia Airport The holiday rush, parents hauling luggage, kids gripping their new Christmas toys,

then everything changed. There's been a bombing at the TWA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit.

Well, Dakota, luckily, it's back-to-school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Hold up. Isn't that against school policy? That seems inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Get fired up, y'all. Season two of Good Game with Sarah Spain is underway. We just welcomed one of my favorite people and incomparable.

soccer icon Megan Rapino to the show, and we had a blast. Take a listen. Sue and I were like riding the lime bikes the other day and we're like, we're like, people write bikes because it's fun. We got more incredible guests like Megan in store, plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. This is an IHeart Podcasts.