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Speaker 1: Hey, Daniel, do you ever wonder if physics might be

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Speaker 1: like really wrong? Are you talking about me or like

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Speaker 1: the entire community? Well, I know you're never wrong, Daniel,

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Speaker 1: that's unthinkable, but you know, like, has physics ever gotten

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Speaker 1: something about the very nature of the universe? Kind of? Uh?

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Speaker 1: Not right? You mean, like what's the best snack food?

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Speaker 1: Or what colored lab coat should we wear? Hey? Yeah,

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Speaker 1: you know, like can I eat antimatter or not? Maybe

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Speaker 1: it's delicious. Physics could definitely be wrong about snacks for you. Well,

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Speaker 1: I mean think bigger, like, is it possible that maybe

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Speaker 1: things are not quite what they seem? Well, it wouldn't

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Speaker 1: be the first time physics is wrong, and I hope

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Speaker 1: it's not the last time. I am organ made cartoonists

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

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Speaker 1: a particle physicist, and I've never been wrong about snack foods,

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Speaker 1: and I've never been wrong about being wrong. So I

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Speaker 1: think that means that I'm always wrong. I don't know,

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Speaker 1: but welcome to our podcast. I'm definitely right about that.

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Speaker 1: This is our podcast, Daniel and Jorge Explain the Universe,

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Speaker 1: a production of I Heart Radio. That's right. Our podcast

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Speaker 1: in which we take a mental tour of all the

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Speaker 1: crazy stuff that's out there in the universe and try

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Speaker 1: to bring it into your head. We try to wrap

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Speaker 1: up the entire universe, all those trillions and trillions of

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Speaker 1: stars and weird blobs of gas and dust and invisible stuff,

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Speaker 1: and inserted through a little hole in your ear into

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Speaker 1: your brain. Yeah, all of the amazing and incredible stuff

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Speaker 1: out there in the universe, and also all of the

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Speaker 1: stuff that's normal. You know, And sometimes I think when

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Speaker 1: you examine what's spears to be normal in your everyday lives,

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Speaker 1: it turns out to have all kinds of wonders and

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Speaker 1: all kinds of small miracles in it. Are there small

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Speaker 1: miracles in your snack foods? Is that what you're talking about? Like, Oh,

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Speaker 1: look this chocolate chips in this trail mix. Every snack

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Speaker 1: is a miracle, Daniel, especially banana's net. But in this podcast,

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Speaker 1: we go beyond the miracles of banana based snack foods

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Speaker 1: and talk about the incredible things that scientists are trying

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Speaker 1: to figure out, Because, contrary to popular perception, scientists don't

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Speaker 1: have it all figured out. There are lots of really

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Speaker 1: big mysteries out there and wondering about the universe is

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Speaker 1: something that belongs to everybody, including you. Yeah, so they're

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Speaker 1: one of the biggest mysteries out there in the universe,

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Speaker 1: and literally sort of like not just like because we

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Speaker 1: don't know it, but also because it's a huge part

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Speaker 1: of the universe. Is dark matter? Dark matter is a

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Speaker 1: little bit crazy, right, It's like twenty of the universe,

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Speaker 1: but we have no idea what it is. That's right

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Speaker 1: of the energy budget of the universe. It's a pretty

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Speaker 1: big slice. It's like a little bit more than a

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Speaker 1: quarter of all the energy in the universe. Is this

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Speaker 1: weird stuff and we've never seen it directly. We're pretty

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Speaker 1: sure it's there, but we don't really know what is it.

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Speaker 1: Is it made out of particles? Isn't made out of

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Speaker 1: black holes? Isn't made out of lost socks? Two really

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Speaker 1: huge mystery in modern physics. In fact, I would say

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Speaker 1: it's one of the biggest open questions in science. I

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Speaker 1: think it's just dark socks actually, but didn't that makes sense?

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Speaker 1: I always lose those. How many dark socks have you

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Speaker 1: lost for her? I mean we're talking a lot of songs. Well,

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Speaker 1: to be out of time a cartoonists I don't have

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Speaker 1: to wear dark socks very often or socks at all,

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Speaker 1: because I also lived in California. But yeah, dark matter,

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Speaker 1: I mean, it's a big deal. There's five times more

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Speaker 1: dark matter than there is regular matter, like planets and

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Speaker 1: stars and gas and dust and black holes, there's all

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Speaker 1: that stuff. There's actually it's only of the stuff in

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Speaker 1: the universe, which means the normal matter, the regular matter,

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Speaker 1: the stuff that you're familiar with, is not actually regular

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Speaker 1: or normal. It's the unusual stuff. If you just took

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Speaker 1: like a survey of stuff in the universe, most of

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Speaker 1: the stuff is dark matter. The things that make up

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Speaker 1: stars and planets and galaxies and hamsters and me and

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Speaker 1: you and bananas and snack foods. That's unusual in the universe.

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Speaker 1: It's a minority of what's out there in the universe.

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Speaker 1: And yet we still don't know what this dark matter is.

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Speaker 1: It's a big mystery and a lot of times, you know,

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Speaker 1: whenever people talk about dark matter, I feel like a

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Speaker 1: common question we get, at least and in talks and

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Speaker 1: appearances is that people ask us like what if dark

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Speaker 1: matter doesn't exist? Like what if it's just an error

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Speaker 1: in the equations that you have about physics and the universe,

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Speaker 1: Like what if we just maybe like misunderstood gravity, or

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Speaker 1: haven't counted all the stars in the galaxy, or you

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Speaker 1: know what if there's something else that is maybe normal

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Speaker 1: but we just haven't thought about. And it's a great

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Speaker 1: question because most of the evidence we have for dark

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Speaker 1: matter is a little bit indirect, like because dark matter

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Speaker 1: is so dark and hard to interact with, we don't

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Speaker 1: have clear pictures of it, right, we haven't seen what

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Speaker 1: it's made out of. We've only sort of seen its

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Speaker 1: effects and sometimes second hand, and so it's tempting to

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Speaker 1: wonder if it's really there. You know. It's like if

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Speaker 1: you've only seen the footprints of an animal, are you

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Speaker 1: really sure it exists? Or could it be something else

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Speaker 1: spoofing you Until you really capture one or see one

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Speaker 1: in the wild, you don't really believe it exists. And

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Speaker 1: dark matter has been eluding our searches for decades and

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Speaker 1: makes people wonder like, well, maybe you people have it wrong. Yeah,

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Speaker 1: I mean it's kind of a crazy idea, right to

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Speaker 1: think that there's that much stuff out there, and conveniently

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Speaker 1: it's invisible and you can't see it. You know what,

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Speaker 1: I mean like I would be like, maybe you should

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Speaker 1: take your math or you know, maybe you should have

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Speaker 1: another grad student do the calculation. So, which do you

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Speaker 1: think is the conspiracy theory dark matter like there's so

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Speaker 1: much of it and you can't see it because it's

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Speaker 1: so dark and that proves that it exists, or the

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Speaker 1: anti dark matter conspiracy theory. Wait, anti dark matter? That's

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Speaker 1: another episode right there? Can you have anti dark matter Danny? Yeah,

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Speaker 1: that's another great question. We think probably not because then

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Speaker 1: they would annihilate a dark matter and turn into photons,

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Speaker 1: which we would see, what if it turns into dark photons? Yeah,

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Speaker 1: that's actually a thing, dark photon. Really? Yeah, there goes

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Speaker 1: my double price. You don't get credit for that one.

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Speaker 1: But you know which idea sounds more bonkers, right, that

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Speaker 1: the universe has filled with an incredible amount of invisible

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Speaker 1: matter nobody had detected until recently, or that it's not. Yeah.

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

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Speaker 1: does the universe need dark matter? Is it an essential

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Speaker 1: part of the unit, Like could you have a universe

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Speaker 1: without dark manner? Does that make sense? Or is it

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Speaker 1: maybe that the universe doesn't need it? And maybe it

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Speaker 1: is kind of an error that we have in our

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Speaker 1: calculations and observations about the universe. And this kind of

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Speaker 1: skepticism is very healthy. When you have a crazy idea

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Speaker 1: you're trying to accommodate when you see results in your

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Speaker 1: experiments you don't understand. You need to be flexible about

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Speaker 1: this sort of theoretical framework with which you come at

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Speaker 1: the problem. You need to be open to crazy new ideas,

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Speaker 1: but you also need to be open to the fact

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Speaker 1: that maybe you got your measurements wrong. There always can

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Speaker 1: be an alternative explanation. So before you go big and say, wow,

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Speaker 1: we're going to revolutionize our understanding of the universe, you've

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Speaker 1: got to rule out all the more prosaic, basic, simpler explanations.

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Speaker 1: And so it's always a good idea to keep those

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Speaker 1: ideas in mind. YEA, So how sure are we that

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Speaker 1: dark matter exists in the universe? And could it be

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Speaker 1: something else? So I went out there into the internet

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Speaker 1: and I asked people, can we explain what we see

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Speaker 1: in the universe without dark matter? Are there good alternative

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Speaker 1: theories that don't require a new particle or a new

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Speaker 1: blob of stuff. Before you listen to these answers from

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Speaker 1: the internet. Think about it for a second. Do you

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Speaker 1: think dark matter is necessary in the universe or do

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Speaker 1: you think the universe could ignore it or live without it.

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Speaker 1: Here's what people had to say. I would think we

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Speaker 1: would be much more baffled if we didn't have dark

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Speaker 1: matter to explain the expansion of the universe. Oh man,

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Speaker 1: And this is tough because I still don't have a

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Speaker 1: good handle on what dark matter really is. But I

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Speaker 1: think I think we really don't know what dark matter is,

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Speaker 1: So I'm going to say, yeah, we could definitely explain

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Speaker 1: what we see without it, because we're kind of just

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Speaker 1: making up what it is. Yes, dark matter is just

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Speaker 1: a made a term for the stuff that's there that

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Speaker 1: we can't explain. So truly, any theory is under the

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Speaker 1: umbrella of dark matter. I have a strong suspicion that

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Speaker 1: the thing could be explained without dark matter, recalled Daniel,

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Speaker 1: saying that dark matter is just the name that we've

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Speaker 1: come up with for the phenomenon that we can't explain.

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Speaker 1: I don't know what we would see without dark matter.

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Speaker 1: My understanding is that we do know that there's dark

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Speaker 1: matter because the math doesn't work out. At some point,

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Speaker 1: we will have to explain the universe without dark matter,

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Speaker 1: because like the dark in the matter sort of implies

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Speaker 1: that we don't know what it is. I believe that

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Speaker 1: dark matter is a theory that we came up with

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Speaker 1: to help explain why we couldn't account for all of

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Speaker 1: the gravity that we see in the universe. I think

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Speaker 1: it's a fairly recent discovery. I don't believe Einstein knew

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Speaker 1: about it, so he must have had some other way

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Speaker 1: to account for all of the gravity. All Right, some

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Speaker 1: pretty good answers there, Yeah. I like the people who

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Speaker 1: treat dark matters just sort of like as an umbrella

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Speaker 1: idea for all the things we don't understand. And so

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Speaker 1: whatever we find out there, we just call that dark matter.

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Speaker 1: And I think that really touches on the sense people

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Speaker 1: have that we don't really have a clue what's out there.

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Speaker 1: We just sort of labeled it dark matter, and we're

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Speaker 1: talking about it as if it's a thing, but it's

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Speaker 1: really just a name we applied to our cluelessness. Interesting,

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Speaker 1: like if you put an S at d end, it

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Speaker 1: becomes dark matters, and then then it's sort of like

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Speaker 1: an umbrella term for things that are dark. That's true,

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Speaker 1: and you know, that is definitely true of dark energy.

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Speaker 1: Dark energy is another piece of the universe pie. Right,

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Speaker 1: the universe pie is five percent normal matter, twenty dark matter,

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Speaker 1: dark energy. Dark energy definitely in the category of just

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Speaker 1: stuff we don't understand. We gave a fancy sounding name

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Speaker 1: dark energy, this stuff that's making the universe expand right.

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Speaker 1: Dark matter, on the other hand, is much better understood,

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Speaker 1: is much more concrete and idea much more detailed observation.

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Speaker 1: So they're both called dark both things we don't understand.

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Speaker 1: But dark energy definitely a label for our cluelessness, while

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Speaker 1: dark matter is a much better founded, well described theory.

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Speaker 1: It's less dark. I guess we're less in the dark

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Speaker 1: about exactly. We are less in the dark. Our minds

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Speaker 1: are not quite so filled with dark shadows. All right.

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Speaker 1: Well that's the question for today, And that's the question is,

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Speaker 1: you know, do we need dark matter, like is it

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Speaker 1: a concept that is totally necessary for the universe to

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Speaker 1: make sense or is it just something weird that exists

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Speaker 1: out there and that maybe we could have a totally

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Speaker 1: wrong idea about, you know, And are there other theories

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Speaker 1: that are being worked on in the scientific community that

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Speaker 1: might explain it without needing to add some new kind

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Speaker 1: of stuff to the universe, darker matter, the darkest matter.

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Speaker 1: And you'll find that in science there are always competing voices.

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Speaker 1: You know, there's often like a mainstream most people think

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Speaker 1: the answer is X, but there's always somebody out there

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Speaker 1: who thinks it's why, somebody who thinks it's Z. And

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Speaker 1: you've got to give these people room because sometimes they're right,

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Speaker 1: and sometimes their ideas of the ones that turn into

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Speaker 1: the mainstream. That's how the mainstream became mainstream. It used

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Speaker 1: to once be lunatic fringe or their alternative physicists, you know,

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Speaker 1: French physicists. There definitely are there are people out there,

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Speaker 1: once they get tenure, start working on crazy Bonker's theories

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Speaker 1: and sometimes for decades that nobody pays attention, nobody really

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Speaker 1: reads their papers, that people even laugh behind their hands.

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Speaker 1: But sometimes they're right, you know. Literally, the history of

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Speaker 1: physics is filled with revolutions that start as crazy ideas,

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Speaker 1: and so we definitely got to pour water on some

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Speaker 1: of those seedlings because they could sprout into huge new

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Speaker 1: intellectual trees, awesome dark physics trees. I'm picturing all right, Well,

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Speaker 1: step us through um like what's the main argument for

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Speaker 1: dark matter, Like, what's the main evidence about it, and

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Speaker 1: what makes this think that, you know, it's something new

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Speaker 1: and different as opposed to maybe it's just more stuff

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Speaker 1: out there that we can't see. Yes, So if you're

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Speaker 1: going to come up with another theory of the universe,

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Speaker 1: another way to explain the way the universe works, you

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Speaker 1: have to explain what we do see, right, I mean

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Speaker 1: that's the whole idea behind making a theory of physics.

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Speaker 1: So if you're gonna come up with your theory, you

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Speaker 1: have to understand what are the observations, what are the

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Speaker 1: experiments reveal that need to be explained that you know,

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Speaker 1: what's the motivation for creating this idea of dark matter?

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Speaker 1: And the short version is it's all gravity. Like everything

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Speaker 1: we see out there in the universe that we need

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Speaker 1: dark matter to explain our weird gravitational effects that we

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Speaker 1: can't explain with all the other stuff, just the gas

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Speaker 1: and the dust and the stars right with the universe

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Speaker 1: feels dark matter in terms of gravity, like it's they're

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Speaker 1: affecting the gravity of other things, but you can't see it.

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Speaker 1: That's the main evidence for it. Yeah, basically there's unexplained gravity,

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Speaker 1: like we thought we knew where all the stuff was

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Speaker 1: in the universe from the stars and the gas and

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Speaker 1: the dust, and from that you can calculate how much

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Speaker 1: gravity there should be, and we can see the effects

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Speaker 1: of gravity, and will go through in a list of

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Speaker 1: how we see the effects of gravity. But there's more

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Speaker 1: gravity than we expected. So either there's more stuff e

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Speaker 1: dark matter, or gravity is weird and different, and so

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Speaker 1: it's all about the gravity then, right, because that's kind

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Speaker 1: of at the basis of the theory about dark matter,

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Speaker 1: is that it feels gravity but not anything else exactly,

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Speaker 1: and that's why it's dark. Because if it felt electromagnetism,

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Speaker 1: it would reflect light, or it would give off light

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Speaker 1: like everything else does than the universe, it glows, or

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Speaker 1: if it felt the strong force, it would bind with

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Speaker 1: corks and form nucleons and interact with us. So it

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Speaker 1: doesn't interact with us in any way that we know

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Speaker 1: of other than gravitational And that's why we call it

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Speaker 1: matter because we think it's something that has new gravity.

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Speaker 1: But you know, it could also just be a tweak

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Speaker 1: to the way we understand gravity. But at its core,

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Speaker 1: it's really an observation that our theory of gravity doesn't

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Speaker 1: work either because there's missing mass or the theory is wrong. Right,

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Speaker 1: So those are two sides of the coin, right, Like,

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Speaker 1: according to what we know about how gravity works, there's

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Speaker 1: a lot of gravity missing, or there's too much gravity

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Speaker 1: in the universe. Almost. Yeah, there's gravity out there and

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Speaker 1: we don't have mass to explain it, and so we

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Speaker 1: have to sort of fill in those gaps. And that's

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Speaker 1: an uncomfortable feeling, right, You're like, well, you can't just

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Speaker 1: like fill in the gaps and assume that your theory

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Speaker 1: is right and add extra stuff to make it work out.

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Speaker 1: You know, that feels uncomfortable, Like there's snack food missing

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Speaker 1: from my fridge. Surely it was my son who cut

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Speaker 1: up in the middle of the night to eat it.

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Speaker 1: But you can't you can't just assume that. You can't

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Speaker 1: just assume that could have been your daughter. Maybe you

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Speaker 1: sleepwalked and aided or or And that's when you install

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Speaker 1: a camera in front of your fridge and you get

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Speaker 1: those weird videos of yourself at four am stuffing cake

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Speaker 1: in your face. Experience the hypothetically hypothetically hypathetically right, Alright,

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Speaker 1: So we think dark matter is there because of gravity.

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Speaker 1: And there are several ways that we have seen this

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Speaker 1: kind of missing gravity, right, that's in the galaxy and rotations.

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Speaker 1: The way galaxies rotade is kind of one of the

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Speaker 1: first one, maybe even Yeah, one of the most dramatic

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Speaker 1: and earliest pieces of evidence that there was more gravity

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Speaker 1: in the universe than we expected was looking at how

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Speaker 1: galaxies rotate. And we can add up all the mass

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Speaker 1: of the stars and the stuff in the galaxy and say, okay,

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Speaker 1: we know how much gravity there should be, and then

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Speaker 1: we can calculate how fast those galaxies are rotating. And

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Speaker 1: you know, for a galaxy, when it's rotating, it's trying

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Speaker 1: to push stuff off. It's trying to throw stuff off

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Speaker 1: the edge. Like if you put ping pong balls on

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Speaker 1: a merry go round and spin it, the ping pong

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Speaker 1: balls fly out. The thing that keeps the galaxy from

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Speaker 1: tearing itself apart from throwing those ping pong balls out

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Speaker 1: into inter galactic space, is the gravity. So you can

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Speaker 1: ask how fast is the galaxy spinning and is there

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Speaker 1: enough gravity to hold it together, because the faster spins,

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Speaker 1: the more gravity unied. Right. Yeah, It's kind of like

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Speaker 1: our solar system, right, like you know, the mass of

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Speaker 1: the Sun is what keeps all the planets kind of

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Speaker 1: spinning around it. But what if, like the planets for

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Speaker 1: spinning faster than what you could explain by the mass

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Speaker 1: of the Sun. You would need some other explanations, that's right,

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Speaker 1: You need more force to hold them into their orbits.

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Speaker 1: And so you say, well, maybe there's extra gravity or

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Speaker 1: some other force or something. And so we know there's

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Speaker 1: something else holding the galaxy together. And so the first explanations,

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Speaker 1: oh well, what if there's more invisible mass. It's just

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Speaker 1: some stuff in the galaxy that's providing gravity and we

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Speaker 1: just can't see it. And you can explain these rotation

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Speaker 1: curves the way the stars move around centers of galaxies.

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Speaker 1: If you distribute a bunch of mass sort of smoothly,

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Speaker 1: it's like a big clump in the middle, and then

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Speaker 1: sort of smoothly outpass the edge of the galaxy into

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Speaker 1: a big halo that's even actually bigger than the galaxy.

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Speaker 1: That explains to this as that would give you the

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Speaker 1: kind of gravity that we are seeing, right, because if

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Speaker 1: you look at a galaxy doesn't have that enough mass, right,

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Speaker 1: like there aren't enough stars or planets in it that

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Speaker 1: you can see. That's right. We count up all the

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Speaker 1: visible stuff and we say how much mass does it have?

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Speaker 1: And that just doesn't give us enough gravity to explain

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Speaker 1: how those galaxies are holding themselves together. And that was

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Speaker 1: the sort of genesis of it. I mean, for a

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Speaker 1: long time people were like, well, wow, that's must be

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Speaker 1: a mistake, you know, because coming to the idea that

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Speaker 1: there's five times as much mass as you can see

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Speaker 1: is a really big idea. It's not something people just

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Speaker 1: came to an afternoon and then accepted, Yeah, it doesn't

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Speaker 1: seem likely. It does not seem likely. It seems more

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Speaker 1: likely that you mismeasured something that you got the velocity

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Speaker 1: is wrong, or you know your grad student is pranking

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Speaker 1: you or something. It's a big idea, right, It's like

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Speaker 1: jumping to the conclusion right away that maybe there are

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Speaker 1: five ghosts in my house eating my snacks. You know,

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Speaker 1: that's like a big that's a big leap from like, hey,

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Speaker 1: maybe it's just your u. And so it took other

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Speaker 1: pieces of evidence before dark matter became mainstream. Right, all right,

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Speaker 1: let's get into those other ways that we know dark

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Speaker 1: matter is there, and let's get into whether or not

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Speaker 1: it is there, or me we just have gravity wrong.

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Speaker 1: But first, let's take a quick break, all right, Daniel,

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Speaker 1: we're talking about whether dark matter is necessary in the

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Speaker 1: universe or you know, maybe it's just the hanger on

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Speaker 1: and the universe could care less about dark matter. But

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Speaker 1: we we know it's definitely there because we see it

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Speaker 1: from the rotation of galaxies and also we've set off

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Speaker 1: kind of can see it, right, We can see it

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Speaker 1: in the way that distorts the light from other far

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Speaker 1: away stars. That's right. These days, we have a good

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Speaker 1: handful of ways to indirectly detect dark matter, and one

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Speaker 1: of the coolest is seeing it act like a lens

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Speaker 1: in the sky because dark matter only has gravitational forces,

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Speaker 1: but gravity can bend space, right, It's a bending of

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Speaker 1: space and time. So if you have a big blob

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Speaker 1: of invisible stuff in the sky, it will curve the

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Speaker 1: space it's in, so that photon is traveling through it

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Speaker 1: will get bent as if they're moving through a huge lens. Right,

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Speaker 1: So if there's a big blob of dark matter between

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Speaker 1: you and some really far away galaxy, it will distort

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Speaker 1: that galaxy, creating duplicates of it, stretching it just as

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Speaker 1: if there was a huge lens in the sky, right,

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Speaker 1: and then we can see that, like if you look

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Speaker 1: at pictures as a sky, you see these kind of distortions,

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Speaker 1: these ripples, these lensing effects. You can sort of see

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Speaker 1: dark matter almost, you can definitely see it. And there's

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Speaker 1: sort of two categories. There's strong lensing, like there's a

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Speaker 1: big dense blob and it's distorting the galaxies and it's

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Speaker 1: pretty hard to explain that kind of lensing in any

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Speaker 1: other way. And then there's weak lensing. We just sort

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Speaker 1: of like look at all the galaxies out there to see, like,

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Speaker 1: are any of them sort of just a little distorted?

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Speaker 1: They're just looking a little tweaked. And from that we

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Speaker 1: can get sort of like a map of where in

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Speaker 1: the sky we think the dark matter is just by

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Speaker 1: looking at small distortions. And that's how we've gotten a

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Speaker 1: pretty good map for where we think this missing mass is.

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Speaker 1: How we know that it's mostly in the center of

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Speaker 1: the galaxy and how far out past the edge of

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Speaker 1: the visible galaxy the dark matter halo might go. So

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Speaker 1: it's a really powerful technique, right, And so that's kind

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Speaker 1: of how dark matter entered in kind of our view

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Speaker 1: of the universe was these first initial ways. But since

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Speaker 1: then and we sort of have put more nails into

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Speaker 1: sort of the coffin of whether or not dark matter

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Speaker 1: is out there, right, I mean, it's now sort of

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Speaker 1: shows up in pictures of the universe, the early universe,

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Speaker 1: it kind of shows up in our calculations about all

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Speaker 1: of the energy in the universe. Right, It's gotten more

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Speaker 1: and more convincing that there's something there that's right, it

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Speaker 1: becomes very difficult to explain the universe you see without

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Speaker 1: dark matter. For example, we see the influence of dark

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Speaker 1: matter on the formation of structures in the universe. Like

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Speaker 1: the universe be in as a sort of diffuse cloud,

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Speaker 1: you know, just of gas, mostly hydrogen, and then it

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Speaker 1: started clumping together, and that clumping comes from gravity. Right,

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Speaker 1: So gravity is the thing that draws these things together

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Speaker 1: and eventually gives you stars and galaxies and planets and

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Speaker 1: all that cool stuff. If you run a stimulation of

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Speaker 1: the universe without any dark matter, then you don't get

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Speaker 1: galaxies in the first ten billion years. It takes like

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Speaker 1: another ten or twenty billion years. So it's dark matter

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Speaker 1: that's that's created these like gravitational wells for stuff to

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Speaker 1: fall into to make the stars in the galaxies and us.

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Speaker 1: So just like the whole structure of the universe would

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Speaker 1: look very different without some kind of gravitational stuff out there,

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Speaker 1: and we should have just called them dark clumps or

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Speaker 1: dark do it. And even earlier in the universe, like

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Speaker 1: we've talked on this program about the cosmic microwave background radiation.

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Speaker 1: Those are photons from the very very early universe, three

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Speaker 1: hundred thousand years after the universe was created, the first

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Speaker 1: moment when the universe became Rand's parent to light. Before

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Speaker 1: that it was thick and soupy and light got reabsorbed,

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Speaker 1: and after that it was cool enough that light could

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Speaker 1: travel through the universe without being absorbed. And the shape

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Speaker 1: of that plasma that gave off that light was affected

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Speaker 1: by dark matter and how much dark matter there was

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00:22:16,080 --> 00:22:18,679
Speaker 1: and much normal matter there was, and that stuff like

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Speaker 1: bounced off each other and oscillated and like squeezed and

429
00:22:22,080 --> 00:22:25,560
Speaker 1: squished that plasma. So the amount of dark matter in

430
00:22:25,640 --> 00:22:28,880
Speaker 1: that moment of the universe affects the shape of that light,

431
00:22:28,960 --> 00:22:31,320
Speaker 1: the currents, the sort of patterns we see in that

432
00:22:31,400 --> 00:22:34,960
Speaker 1: light in a very very precise way that's hard to

433
00:22:35,000 --> 00:22:38,400
Speaker 1: describe in any other way other than there's some other

434
00:22:38,520 --> 00:22:42,200
Speaker 1: kind of stuff out there. So that's giving us this graphic. Yeah,

435
00:22:42,240 --> 00:22:44,679
Speaker 1: you can see like it's imprint in the light from

436
00:22:44,720 --> 00:22:48,359
Speaker 1: the early universe, Like it's visually and like tangibly and like,

437
00:22:49,040 --> 00:22:51,679
Speaker 1: you know, you can calculate it the storts that light.

438
00:22:51,760 --> 00:22:53,920
Speaker 1: That's right. And so if you just take the universe

439
00:22:53,920 --> 00:22:56,920
Speaker 1: and you add to it a new particle, a particle

440
00:22:56,920 --> 00:22:59,720
Speaker 1: that doesn't move really fast, we call it cold and

441
00:22:59,800 --> 00:23:03,399
Speaker 1: doesn't feel anything but gravity, it explains all of this stuff.

442
00:23:03,440 --> 00:23:06,760
Speaker 1: It explains why galaxies rotate the way they do, why

443
00:23:06,800 --> 00:23:09,880
Speaker 1: the cosmic microwave background rediation looks the way it does,

444
00:23:10,200 --> 00:23:13,880
Speaker 1: why the structure of the universe has this structure at

445
00:23:13,880 --> 00:23:17,600
Speaker 1: this time in the universe. And also there are very specific,

446
00:23:17,880 --> 00:23:20,919
Speaker 1: awesome experiments that the universe has done to sort of

447
00:23:20,960 --> 00:23:24,399
Speaker 1: demonstrate dark matter to us. Yeah, I guess, you know,

448
00:23:24,480 --> 00:23:27,160
Speaker 1: I think maybe a question that a lot of people have,

449
00:23:27,280 --> 00:23:29,520
Speaker 1: and I'm sure if physicists had at the beginning, was,

450
00:23:29,960 --> 00:23:32,800
Speaker 1: you know, why does it need to be something special?

451
00:23:32,920 --> 00:23:35,200
Speaker 1: Like why does it need to be a new kind

452
00:23:35,200 --> 00:23:39,680
Speaker 1: of particle or matter? Couldn't it also just be something regular?

453
00:23:39,760 --> 00:23:41,560
Speaker 1: But that you just can't see, Like, you know, what

454
00:23:41,600 --> 00:23:44,040
Speaker 1: if there's a whole bunch of black asteroids out there

455
00:23:44,119 --> 00:23:46,720
Speaker 1: that are hard to see, or you know, a lot

456
00:23:46,800 --> 00:23:49,359
Speaker 1: of small dust that we can see, or maybe even

457
00:23:49,400 --> 00:23:51,560
Speaker 1: like a whole bunch of little black holes kind of

458
00:23:51,600 --> 00:23:53,919
Speaker 1: spread around the universe. Yeah, that's a great question, like

459
00:23:53,960 --> 00:23:56,040
Speaker 1: why do we know it's a new kind of thing.

460
00:23:56,200 --> 00:23:57,920
Speaker 1: Why can't it just be more of the same but

461
00:23:58,040 --> 00:24:01,080
Speaker 1: just kind of dark, right? Yeah, yeah, Well we don't

462
00:24:01,080 --> 00:24:04,640
Speaker 1: really know anything in our current set of particles that

463
00:24:04,880 --> 00:24:08,440
Speaker 1: is that dark. I mean, other than neutrinos. Everything else

464
00:24:08,520 --> 00:24:11,200
Speaker 1: has some kind of interaction, like if it's a black

465
00:24:11,359 --> 00:24:14,240
Speaker 1: rock or something, well that does reflect light, it does

466
00:24:14,359 --> 00:24:16,639
Speaker 1: give off light. So if it's made out of the

467
00:24:16,680 --> 00:24:18,560
Speaker 1: normal kind of matter, it's going to have the kind

468
00:24:18,560 --> 00:24:22,320
Speaker 1: of interactions we have, and therefore we would be able

469
00:24:22,359 --> 00:24:26,360
Speaker 1: to see it, except of course, neutrinos. Neutrinos were candidate

470
00:24:26,400 --> 00:24:28,239
Speaker 1: for dark matter for a long time. The problem is

471
00:24:28,359 --> 00:24:31,879
Speaker 1: neutrinos move away too fast, they zoom around the universe

472
00:24:31,920 --> 00:24:34,280
Speaker 1: because they're so light, so they don't give the same

473
00:24:34,280 --> 00:24:37,200
Speaker 1: sort of structure to the universe that dark matter does.

474
00:24:37,240 --> 00:24:39,439
Speaker 1: You need this thing to be sort of slow moving

475
00:24:39,480 --> 00:24:42,399
Speaker 1: and cold in order to stick around long enough to

476
00:24:42,480 --> 00:24:46,240
Speaker 1: give the structure of galaxies. Could you have cold neutrinos

477
00:24:46,320 --> 00:24:48,560
Speaker 1: like slow moving neutrinos. Then we talk about that the

478
00:24:48,600 --> 00:24:51,800
Speaker 1: other in another episode. Could you have cold neutrinos, Yes,

479
00:24:52,160 --> 00:24:55,240
Speaker 1: but we don't think that neutrinos are that cold. We

480
00:24:55,320 --> 00:24:58,600
Speaker 1: haven't seen cold neutrinos. Neutrinos are so light they have

481
00:24:58,680 --> 00:25:02,240
Speaker 1: almost no mass that they essentially almost always travel near

482
00:25:02,280 --> 00:25:05,080
Speaker 1: the speed of light. They're always in a rush, They're

483
00:25:05,080 --> 00:25:08,040
Speaker 1: always in a hurry. Yes, neutrinos are hot, as we

484
00:25:08,119 --> 00:25:12,800
Speaker 1: call them in particle physics. And it literally and figuratively

485
00:25:12,920 --> 00:25:15,840
Speaker 1: is it's it's a pretty big trend right now, that's right,

486
00:25:15,880 --> 00:25:18,040
Speaker 1: all right? Well, I guess if it's not maybe something

487
00:25:18,080 --> 00:25:20,119
Speaker 1: we know about, could it be that just maybe we

488
00:25:20,160 --> 00:25:23,280
Speaker 1: have our theories wrong about how things work, Like, you know,

489
00:25:23,320 --> 00:25:25,320
Speaker 1: maybe it's not a new particle or a new kind

490
00:25:25,359 --> 00:25:28,439
Speaker 1: of matter, but maybe we just have gravity wrong. Like

491
00:25:28,520 --> 00:25:31,320
Speaker 1: maybe gravity doesn't work the way we think it is.

492
00:25:31,320 --> 00:25:36,080
Speaker 1: And maybe these larger universe size scales could gravity, you know,

493
00:25:36,160 --> 00:25:38,320
Speaker 1: could there be a different theory of gravity that would

494
00:25:38,320 --> 00:25:40,920
Speaker 1: maybe account for what we think is dark matter. It's

495
00:25:40,960 --> 00:25:44,560
Speaker 1: definitely something to consider, right, because all these observations are

496
00:25:44,640 --> 00:25:48,080
Speaker 1: just observations of gravity. And what we're doing is we're saying,

497
00:25:48,240 --> 00:25:50,440
Speaker 1: we assume there's a certain amount of mass out there,

498
00:25:50,720 --> 00:25:53,560
Speaker 1: we assume we know how gravity works. We estimate how

499
00:25:53,600 --> 00:25:56,440
Speaker 1: much gravity there should be based on that mass. Right,

500
00:25:56,440 --> 00:25:58,679
Speaker 1: But there are two steps in there. There's figure out

501
00:25:58,760 --> 00:26:01,600
Speaker 1: where the mass is and in calculate how much gravity

502
00:26:01,640 --> 00:26:05,080
Speaker 1: there is from that mass. If that second step is wrong, right,

503
00:26:05,240 --> 00:26:07,960
Speaker 1: if the theory of gravity works differently from what we expected,

504
00:26:08,160 --> 00:26:11,800
Speaker 1: then yeah, that could possibly explain it. Because remember, gravity

505
00:26:11,920 --> 00:26:14,840
Speaker 1: is very very weak, which makes it very very hard

506
00:26:14,880 --> 00:26:18,199
Speaker 1: to test, Like it's difficult to measure the force of

507
00:26:18,280 --> 00:26:22,000
Speaker 1: gravity at the scale of one centimeter between two pebbles

508
00:26:22,520 --> 00:26:26,280
Speaker 1: because there's force there's almost zero, Like you need to

509
00:26:26,280 --> 00:26:29,880
Speaker 1: build a very sensitive instrument to measure the gravitational force

510
00:26:29,920 --> 00:26:33,440
Speaker 1: between anything that's smaller than you know, planets and moons. Yeah,

511
00:26:33,480 --> 00:26:36,520
Speaker 1: because you know, like our current theory of gravity says that,

512
00:26:36,640 --> 00:26:40,239
Speaker 1: you know, gravity changes by one of our squared, Like

513
00:26:40,280 --> 00:26:43,080
Speaker 1: the force of gravity kind of depends on the distance

514
00:26:43,119 --> 00:26:45,720
Speaker 1: between two things squared. And then you put down in

515
00:26:45,760 --> 00:26:49,120
Speaker 1: the denominator and that always seems kind of almost too

516
00:26:49,119 --> 00:26:51,520
Speaker 1: simple to me, Like, what are the chances at the

517
00:26:51,600 --> 00:26:55,240
Speaker 1: universe would pick such a simple little formula to calculate gravity.

518
00:26:55,320 --> 00:26:58,480
Speaker 1: You know, why isn't it like one over our squared

519
00:26:58,680 --> 00:27:01,639
Speaker 1: times are to the zero point seven five? You know,

520
00:27:01,960 --> 00:27:04,199
Speaker 1: I mean, like it seems so simple. Maybe what if

521
00:27:04,200 --> 00:27:06,040
Speaker 1: it's wrong, Like what if gravity isn't one of our

522
00:27:06,040 --> 00:27:09,240
Speaker 1: our square but maybe changes over distances in a way

523
00:27:09,359 --> 00:27:11,840
Speaker 1: that could maybe explain dark matter. Yeah, that's a totally

524
00:27:11,840 --> 00:27:14,160
Speaker 1: realistic thing to think. Although you know, there's a lot

525
00:27:14,160 --> 00:27:16,440
Speaker 1: of these patterns, these one of our our squared patterns

526
00:27:16,440 --> 00:27:19,280
Speaker 1: in physics and enforces and there is a good reason

527
00:27:19,320 --> 00:27:21,240
Speaker 1: for it and a fairly simple way to understand it.

528
00:27:21,480 --> 00:27:24,520
Speaker 1: If you imagine like the surface of a sphere surrounding

529
00:27:24,560 --> 00:27:27,320
Speaker 1: a point. Think about like all the gravitational energy coming

530
00:27:27,320 --> 00:27:30,040
Speaker 1: out of a point, the surface of a sphere surrounding it,

531
00:27:30,440 --> 00:27:33,640
Speaker 1: all the gravitational energy passes through that sphere, and then

532
00:27:33,800 --> 00:27:36,600
Speaker 1: as the radius of that sphere gets larger, what's the

533
00:27:36,640 --> 00:27:39,480
Speaker 1: surface of that sphere? Will it goes like are squared,

534
00:27:39,920 --> 00:27:42,560
Speaker 1: and so the power at any point should go like

535
00:27:42,680 --> 00:27:46,480
Speaker 1: one over our squared. It sort of makes sense geometrically

536
00:27:46,840 --> 00:27:50,160
Speaker 1: but what if geometry is wrong. What if geometry is wrong? Right?

537
00:27:50,359 --> 00:27:54,879
Speaker 1: What is wrong? What if podcasting is wrong? What if

538
00:27:54,880 --> 00:27:56,920
Speaker 1: one plus one is wrong? Well, it kind of, I mean,

539
00:27:57,119 --> 00:27:59,920
Speaker 1: you know, we talk about sometimes about how space is

540
00:28:00,080 --> 00:28:02,679
Speaker 1: not you know, this nice and neat, orderly thing, and

541
00:28:02,720 --> 00:28:06,560
Speaker 1: that sometimes you can even like measure triangles in real

542
00:28:06,600 --> 00:28:09,560
Speaker 1: space that have angles that are bigger than a hundred

543
00:28:09,600 --> 00:28:13,199
Speaker 1: and eighty degrees, could maybe, like space be weird in

544
00:28:13,280 --> 00:28:16,520
Speaker 1: such a way that it's not really one over our squares? Yeah? Absolutely,

545
00:28:16,520 --> 00:28:18,560
Speaker 1: And there are forces that don't go like one of

546
00:28:18,560 --> 00:28:20,800
Speaker 1: our our squared, Like the strong force doesn't go like

547
00:28:20,800 --> 00:28:23,520
Speaker 1: one of our squared at small distances. It gets even

548
00:28:23,640 --> 00:28:26,560
Speaker 1: stronger as you get further away. So you definitely got

549
00:28:26,560 --> 00:28:29,400
Speaker 1: to be open to weirdness. And so around the time

550
00:28:29,440 --> 00:28:31,480
Speaker 1: when dark matter was sort of coming up in the

551
00:28:31,520 --> 00:28:34,320
Speaker 1: world as an idea, when it was based mostly on

552
00:28:34,440 --> 00:28:37,800
Speaker 1: galaxy rotations, people thought, well, how can I tweak gravity

553
00:28:38,080 --> 00:28:41,240
Speaker 1: to explain what I'm seeing without dark matter? What would

554
00:28:41,240 --> 00:28:42,960
Speaker 1: I need to change? How what would you have to

555
00:28:42,960 --> 00:28:44,880
Speaker 1: be like one over our to the third or one

556
00:28:44,880 --> 00:28:47,360
Speaker 1: of our at one point five or whatever in order

557
00:28:47,360 --> 00:28:51,200
Speaker 1: to explain these galaxy rotations without dark matter, and so

558
00:28:51,240 --> 00:28:54,600
Speaker 1: they came up with a different theory. It's called mond

559
00:28:54,960 --> 00:29:01,760
Speaker 1: m O n D for modified Newtonian dynamics. Know, I

560
00:29:01,760 --> 00:29:04,000
Speaker 1: would have just called the dark bath. I wish you

561
00:29:04,040 --> 00:29:05,760
Speaker 1: could get in a time machine and go back and

562
00:29:05,800 --> 00:29:08,160
Speaker 1: tell them because I hate moms. Would that be a

563
00:29:08,160 --> 00:29:13,520
Speaker 1: lot catch here and fun? Dark bath? Well, mon, I

564
00:29:13,520 --> 00:29:15,920
Speaker 1: guess if you're French, then it's like, oh, yeah, it

565
00:29:15,960 --> 00:29:19,080
Speaker 1: means the world. I suppose it's missing the E and

566
00:29:19,120 --> 00:29:21,959
Speaker 1: it commits the terrible acronym crime of taking two letters

567
00:29:21,960 --> 00:29:26,120
Speaker 1: from one of the words, you know, modified. Yeah, all right,

568
00:29:26,160 --> 00:29:28,840
Speaker 1: so there is a kind of a theory in physics.

569
00:29:28,920 --> 00:29:31,080
Speaker 1: It says like maybe we do have gravity wrong, right,

570
00:29:31,640 --> 00:29:33,920
Speaker 1: is like an idea you guys take seriously, like maybe

571
00:29:34,040 --> 00:29:36,360
Speaker 1: there is no dark matter, it's just dark bath. It's

572
00:29:36,360 --> 00:29:39,120
Speaker 1: definitely an idea that physics should take seriously in the

573
00:29:39,160 --> 00:29:42,320
Speaker 1: sense that we should think about alternatives. This one theory

574
00:29:42,320 --> 00:29:44,920
Speaker 1: in particular doesn't have a lot of supporters, and we'll

575
00:29:44,920 --> 00:29:47,640
Speaker 1: get into exactly why, but you know, it's an interesting

576
00:29:47,680 --> 00:29:52,000
Speaker 1: idea and it says like maybe gravity works differently at

577
00:29:52,160 --> 00:29:55,640
Speaker 1: very very large distances, like you know, we've tested gravity

578
00:29:55,680 --> 00:29:57,880
Speaker 1: here on Earth. We know how it works. We've tested

579
00:29:57,880 --> 00:30:00,560
Speaker 1: gravity in the Solar System pretty well. But you know,

580
00:30:00,640 --> 00:30:03,800
Speaker 1: maybe the first time we're looking at gravity on galaxy scales,

581
00:30:03,880 --> 00:30:07,320
Speaker 1: maybe gravity just works differently over like, you know, fifty

582
00:30:07,400 --> 00:30:10,840
Speaker 1: thou light years, right, we haven't done that experiment before.

583
00:30:10,920 --> 00:30:13,640
Speaker 1: Maybe it gets going, like, maybe it gets stronger in

584
00:30:13,960 --> 00:30:16,880
Speaker 1: galaxy size scales. Yeah, And so the idea is actually

585
00:30:16,920 --> 00:30:20,560
Speaker 1: even weirder than that. It says, maybe gravity works differently

586
00:30:21,280 --> 00:30:25,840
Speaker 1: when you have a very very small acceleration, things are

587
00:30:25,880 --> 00:30:30,720
Speaker 1: not being pulled very hard. Maybe gravity works a little

588
00:30:30,720 --> 00:30:32,600
Speaker 1: bit different. Oh my god, you just blew my mind.

589
00:30:32,600 --> 00:30:35,560
Speaker 1: All right, let's let's get into this crazy idea that

590
00:30:35,600 --> 00:30:39,040
Speaker 1: gravity depends on how you're moving maybe, and whether or

591
00:30:39,080 --> 00:30:55,040
Speaker 1: not that could work. But first let's take another quick break, right, Daniel,

592
00:30:55,080 --> 00:30:58,600
Speaker 1: we're talking about dark math to maybe explain dark matter.

593
00:30:58,920 --> 00:31:01,880
Speaker 1: And so there's an idea that maybe our formulation of

594
00:31:01,880 --> 00:31:04,400
Speaker 1: gravity or how we think gravity works could be wrong.

595
00:31:04,440 --> 00:31:08,080
Speaker 1: Maybe and it could maybe act very differently over larger scales,

596
00:31:08,120 --> 00:31:11,160
Speaker 1: like maybe it gets stronger the galaxy scale or when

597
00:31:11,360 --> 00:31:14,240
Speaker 1: you're telling me it's actually when there's lower accelerations. And

598
00:31:14,240 --> 00:31:16,200
Speaker 1: this is just an idea again, right, this is just

599
00:31:16,240 --> 00:31:18,640
Speaker 1: an idea. But hey, everything is just an idea, right,

600
00:31:18,680 --> 00:31:21,960
Speaker 1: even lunch lunch is just an idea. Remember, Oh no, Daniel,

601
00:31:22,080 --> 00:31:25,080
Speaker 1: lunch is very real to me. Well, the idea is,

602
00:31:25,240 --> 00:31:27,120
Speaker 1: you know, somehow you have to get gravity to be

603
00:31:27,280 --> 00:31:30,840
Speaker 1: stronger without breaking things we already know. So what if

604
00:31:30,960 --> 00:31:33,480
Speaker 1: you know affecting things on the edge of the galaxy,

605
00:31:33,760 --> 00:31:35,920
Speaker 1: you could have gravity instead of going like one over

606
00:31:36,000 --> 00:31:38,640
Speaker 1: our squared, which you make it very very weak as

607
00:31:38,640 --> 00:31:40,760
Speaker 1: our gets large, you can make it go like one

608
00:31:40,800 --> 00:31:43,760
Speaker 1: over R. It doesn't fall off as quickly, doesn't get

609
00:31:43,800 --> 00:31:47,560
Speaker 1: weak as quickly with large distances. Interesting, So like the

610
00:31:47,640 --> 00:31:50,880
Speaker 1: gravity I feel with another planet on the other side

611
00:31:50,880 --> 00:31:54,400
Speaker 1: of the Milky Way, maybe it's stronger than I think. Yeah,

612
00:31:54,480 --> 00:31:56,560
Speaker 1: maybe it's not like one over our squares, more like

613
00:31:56,600 --> 00:31:59,240
Speaker 1: one over R and R is still really really large.

614
00:31:59,360 --> 00:32:01,880
Speaker 1: So you know, those planets don't affect you because the

615
00:32:01,960 --> 00:32:04,880
Speaker 1: gravity from them is still really tiny. But if you're

616
00:32:04,880 --> 00:32:07,040
Speaker 1: adding up lots of planets and you're trying to calculate,

617
00:32:07,040 --> 00:32:10,040
Speaker 1: like how a whole galaxy spins, then it really does

618
00:32:10,120 --> 00:32:11,960
Speaker 1: make a big difference to go like one of our

619
00:32:11,960 --> 00:32:15,360
Speaker 1: are instead of one of are squared. But it seems

620
00:32:15,400 --> 00:32:18,720
Speaker 1: a bit hacky as opposed to dark matter. Dark matter

621
00:32:18,760 --> 00:32:21,360
Speaker 1: doesn't seem hacky. Well, dark matter, you know, you can

622
00:32:21,440 --> 00:32:24,640
Speaker 1: explain a lot of really different things adding just one

623
00:32:24,760 --> 00:32:27,200
Speaker 1: simple idea, like hey, what if there's a new particle

624
00:32:27,480 --> 00:32:29,800
Speaker 1: that's not hacky, Like we don't know why there's a

625
00:32:29,800 --> 00:32:31,960
Speaker 1: certain number of particles in the universe and not more,

626
00:32:32,120 --> 00:32:34,800
Speaker 1: or if there are more, so adding one new particle

627
00:32:34,800 --> 00:32:37,600
Speaker 1: doesn't feel as hacky. Is like let's have gravity have

628
00:32:37,640 --> 00:32:40,160
Speaker 1: a knob on it, or like a distance above which

629
00:32:40,160 --> 00:32:44,000
Speaker 1: it starts behaving different rules, or you know, small accelerations

630
00:32:44,040 --> 00:32:46,920
Speaker 1: below which it starts behaving differently. Really, what why does

631
00:32:46,920 --> 00:32:49,320
Speaker 1: it need to be low accelerations? How does that work? In?

632
00:32:49,720 --> 00:32:52,000
Speaker 1: It doesn't really work as I think I heard you

633
00:32:52,040 --> 00:32:55,000
Speaker 1: react because like the acceleration with respect to what right,

634
00:32:55,040 --> 00:32:57,600
Speaker 1: all of a sudden, that gravity you feel depends on

635
00:32:57,680 --> 00:33:00,720
Speaker 1: your reference frame, and it brings all sorts of symmetries.

636
00:33:00,960 --> 00:33:04,560
Speaker 1: But there is that one idea that accelerations like one

637
00:33:04,560 --> 00:33:07,280
Speaker 1: ten trillions of the gravity on Earth. If you feel

638
00:33:07,280 --> 00:33:10,080
Speaker 1: an acceleration less than that, then the gravity on you

639
00:33:10,400 --> 00:33:14,160
Speaker 1: behaves differently than it does for larger accelerations. Oh, I see.

640
00:33:14,240 --> 00:33:16,600
Speaker 1: It's not you're not saying when you're going at a

641
00:33:16,680 --> 00:33:19,600
Speaker 1: low acceleration, it's just you mean the when the effects

642
00:33:19,640 --> 00:33:21,760
Speaker 1: of gravity are small, maybe it doesn't behave as one

643
00:33:21,800 --> 00:33:24,000
Speaker 1: over our square. Yeah, and the effects of gravity at

644
00:33:24,120 --> 00:33:27,440
Speaker 1: very very far distances are really small. Like what is

645
00:33:27,520 --> 00:33:30,280
Speaker 1: the acceleration on some star at the edge of the

646
00:33:30,320 --> 00:33:33,560
Speaker 1: galaxy due to the black hole the center of the galaxy. Well,

647
00:33:33,640 --> 00:33:36,600
Speaker 1: the distance is fifty thou light years, so the acceleration

648
00:33:37,160 --> 00:33:40,560
Speaker 1: is very small, also because the masses are large, and

649
00:33:40,600 --> 00:33:42,760
Speaker 1: so it's just a way to say, let's have it

650
00:33:42,800 --> 00:33:46,000
Speaker 1: have an effect where we see this weirdness and not

651
00:33:46,120 --> 00:33:48,400
Speaker 1: have an effect anywhere else. Let's try not to break

652
00:33:48,760 --> 00:33:51,280
Speaker 1: what we already know and understand and only have this

653
00:33:51,400 --> 00:33:54,560
Speaker 1: theory turn on in special cases. All right, so that's

654
00:33:54,560 --> 00:33:56,880
Speaker 1: a possibility. But where did this idea come from? Like

655
00:33:57,000 --> 00:33:59,200
Speaker 1: why would we think that maybe gravity is wrong? So

656
00:33:59,280 --> 00:34:01,080
Speaker 1: for a long time there wasn't really a good idea

657
00:34:01,120 --> 00:34:02,880
Speaker 1: that was just like, well, I don't know, but if

658
00:34:02,920 --> 00:34:05,280
Speaker 1: I put in this other formula, I can explain the

659
00:34:05,280 --> 00:34:09,120
Speaker 1: galaxy rotation curves without dark matter. Without dark matter. Yeah,

660
00:34:09,120 --> 00:34:11,560
Speaker 1: So like all right, so either there's missing masks or

661
00:34:11,600 --> 00:34:15,200
Speaker 1: gravity works this other weird way, and then people started thinking, well,

662
00:34:15,239 --> 00:34:18,080
Speaker 1: why would gravity work that way? Is there any reason

663
00:34:18,200 --> 00:34:20,680
Speaker 1: for it? And that's a totally valid line of inquiry, right,

664
00:34:20,719 --> 00:34:22,760
Speaker 1: like what theory do we have to have to explain

665
00:34:22,800 --> 00:34:25,319
Speaker 1: the data? And does that theory make sense? Can we

666
00:34:25,320 --> 00:34:27,879
Speaker 1: come up with a reason why? Maybe that theory is right?

667
00:34:28,320 --> 00:34:32,279
Speaker 1: A theory about a theory underpinnings of the theory, right.

668
00:34:32,440 --> 00:34:35,240
Speaker 1: We always in physics want to have a microscopic understanding.

669
00:34:35,239 --> 00:34:37,279
Speaker 1: We don't want to just say gravity just has this

670
00:34:37,360 --> 00:34:39,120
Speaker 1: number on it. We want to know why does it?

671
00:34:39,120 --> 00:34:41,399
Speaker 1: Where does that come from? Why isn't it something else?

672
00:34:41,440 --> 00:34:43,239
Speaker 1: Just like you were saying earlier, why is it one

673
00:34:43,280 --> 00:34:45,600
Speaker 1: of our square not one over our two point one

674
00:34:45,719 --> 00:34:50,920
Speaker 1: or whatever? That's the next version upgraded gravity. And so

675
00:34:51,040 --> 00:34:54,040
Speaker 1: recently there is an idea from a guy in Holland

676
00:34:54,080 --> 00:34:57,480
Speaker 1: to Eric Verlinda, and he has this crazy idea of

677
00:34:57,520 --> 00:35:01,440
Speaker 1: gravity called entropic gravity that i'd be able to explain

678
00:35:02,000 --> 00:35:06,480
Speaker 1: why gravity works differently at these distance scales. I feel

679
00:35:06,480 --> 00:35:08,719
Speaker 1: like maybe he just grabbed two cool sounding things and

680
00:35:08,719 --> 00:35:14,000
Speaker 1: put them together. Tropic answer like dynamic gravity or something.

681
00:35:14,040 --> 00:35:15,840
Speaker 1: But it comes from a cool place. You know, it

682
00:35:15,880 --> 00:35:21,520
Speaker 1: was Stephen Hawking who first connected sort of thermodynamics and gravity.

683
00:35:21,680 --> 00:35:25,400
Speaker 1: He started thinking about the temperature of black holes and thinking,

684
00:35:25,760 --> 00:35:28,600
Speaker 1: you know, if black holes have temperatures, that means they

685
00:35:28,600 --> 00:35:32,000
Speaker 1: should radiate. Oh wait, and that's Hawking radiation. So in

686
00:35:32,000 --> 00:35:34,160
Speaker 1: the last sort of forty years, people have been thinking

687
00:35:34,200 --> 00:35:37,359
Speaker 1: about gravity and through our dynamics as a connection. They're

688
00:35:37,360 --> 00:35:40,839
Speaker 1: trying to understand like, you know, actually, maybe gravity isn't

689
00:35:40,880 --> 00:35:44,879
Speaker 1: a fundamental force, and maybe, you know Einstein's idea that

690
00:35:44,960 --> 00:35:48,680
Speaker 1: gravity is just a curvature spacetime, maybe that's also wrong.

691
00:35:49,000 --> 00:35:54,080
Speaker 1: Maybe instead, gravity is just like an emergent phenomena of thermodynamics.

692
00:35:54,600 --> 00:35:58,480
Speaker 1: Maybe it's just like comes out of the manipulation and

693
00:35:58,560 --> 00:36:02,000
Speaker 1: interaction of some tiny little bits of space in a

694
00:36:02,040 --> 00:36:05,560
Speaker 1: way that feels like gravity to us. That's a little

695
00:36:05,560 --> 00:36:08,080
Speaker 1: bit mind blowing. Yeah, it's a little bit mind blowing.

696
00:36:08,160 --> 00:36:11,000
Speaker 1: This whole idea of emergent phenomena can be hard to

697
00:36:11,000 --> 00:36:13,239
Speaker 1: get your mind around, but it's actually very familiar. You know,

698
00:36:13,320 --> 00:36:16,480
Speaker 1: Like we can talk about wind, right, Wind is an

699
00:36:16,520 --> 00:36:19,440
Speaker 1: emergent phenomena. It's not a fundamental force in the universe.

700
00:36:19,760 --> 00:36:23,239
Speaker 1: You know, two particles interacting don't feel wind. Wind is

701
00:36:23,280 --> 00:36:25,960
Speaker 1: a combination of lots of other things we do understand

702
00:36:26,000 --> 00:36:30,279
Speaker 1: on a microscopical level that has a macroscopic effect, or

703
00:36:30,400 --> 00:36:33,680
Speaker 1: like economics. You know, there are laws of economics that

704
00:36:33,760 --> 00:36:35,920
Speaker 1: come from you know, supply and demand or whatever. It's

705
00:36:35,960 --> 00:36:38,440
Speaker 1: not a fundamental force in the universe, but still you

706
00:36:38,440 --> 00:36:41,080
Speaker 1: could have an understanding of it. And so they think

707
00:36:41,120 --> 00:36:45,880
Speaker 1: maybe gravity is just like a macroscopic effect of something microscopic,

708
00:36:45,920 --> 00:36:49,840
Speaker 1: maybe the thermodynamics of space time. Like there there is

709
00:36:49,880 --> 00:36:53,279
Speaker 1: no gravity, it's just kind of like how space itself

710
00:36:53,400 --> 00:36:56,560
Speaker 1: kind of arranges itself. Yeah, because we know that space

711
00:36:56,719 --> 00:37:00,640
Speaker 1: likes to increase entropy, likes to increase disorder, and so

712
00:37:00,719 --> 00:37:03,440
Speaker 1: we think entropy always increases in the universe, and so

713
00:37:03,520 --> 00:37:05,960
Speaker 1: maybe gravity is just an effect of that. You know.

714
00:37:06,000 --> 00:37:08,560
Speaker 1: The argument goes something like when things fall into a

715
00:37:08,600 --> 00:37:12,000
Speaker 1: black hole, for example, that increases the entropy of the

716
00:37:12,040 --> 00:37:14,839
Speaker 1: black hole, because otherwise it would violate the second law

717
00:37:14,880 --> 00:37:18,040
Speaker 1: of thermodynamics. Things can't just disappear into the black hole.

718
00:37:18,520 --> 00:37:21,480
Speaker 1: But maybe it's the opposite. Maybe it's not that gravity

719
00:37:21,520 --> 00:37:24,520
Speaker 1: pulls things into the black hole and then increases the entropy.

720
00:37:24,640 --> 00:37:28,239
Speaker 1: Maybe it's entropy that's pushing things into black holes, and

721
00:37:28,280 --> 00:37:31,239
Speaker 1: that's actually what gravity is. That's just like you know,

722
00:37:31,280 --> 00:37:34,440
Speaker 1: the way gas diffuses in a box. You put a

723
00:37:34,440 --> 00:37:36,480
Speaker 1: blob of gas in the corner of a box and

724
00:37:36,520 --> 00:37:40,439
Speaker 1: it spreads out into the box. That's entropy the same way.

725
00:37:40,480 --> 00:37:44,040
Speaker 1: Maybe entropy is stuff falling into itself, like you know,

726
00:37:44,160 --> 00:37:48,400
Speaker 1: having more stuff near itself dense blobs of mass increases

727
00:37:48,440 --> 00:37:51,839
Speaker 1: the temperature, which changes the entropy of the situation. I mean,

728
00:37:51,920 --> 00:37:55,760
Speaker 1: it's a complicated argument involving like quantum entangled space time,

729
00:37:55,800 --> 00:37:57,799
Speaker 1: but I think that's the gist of it, and all

730
00:37:57,840 --> 00:38:00,680
Speaker 1: of that kind of crazy idea is just explain how

731
00:38:00,800 --> 00:38:03,760
Speaker 1: maybe gravity could not be one over our square. Yeah,

732
00:38:03,800 --> 00:38:06,560
Speaker 1: if you have in tropic gravity, so maybe if gravity

733
00:38:06,719 --> 00:38:09,319
Speaker 1: is not a fundamental force in the universe but just

734
00:38:09,400 --> 00:38:13,000
Speaker 1: like an emergent property of quantum space time, and you

735
00:38:13,040 --> 00:38:17,520
Speaker 1: have dark energy, then Virlindis theory predicts that space curs

736
00:38:17,560 --> 00:38:20,800
Speaker 1: in this way, that gravity, the effective force of gravity,

737
00:38:21,120 --> 00:38:24,480
Speaker 1: goes the way mind needs it to explain the galactic

738
00:38:24,560 --> 00:38:28,279
Speaker 1: rotation curves. So that's kind of cool thing. That's an

739
00:38:28,320 --> 00:38:31,239
Speaker 1: alternative to dark matter. Is one alternative to dark matter

740
00:38:31,320 --> 00:38:35,920
Speaker 1: to say we have this weird gravitational thermodynamics idea that

741
00:38:36,000 --> 00:38:39,239
Speaker 1: changes the way gravity works. That explains why we thought

742
00:38:39,320 --> 00:38:42,200
Speaker 1: that was missing stuff. Instead, it's just the gravity works

743
00:38:42,200 --> 00:38:44,759
Speaker 1: differently than we expect it. Interesting alright, So then I

744
00:38:44,760 --> 00:38:47,719
Speaker 1: guess the big question is could that work? Is that

745
00:38:47,840 --> 00:38:52,560
Speaker 1: a valid or plausible theory that maybe explains gravity in

746
00:38:52,560 --> 00:38:56,040
Speaker 1: a different way that then explains dark matter and and

747
00:38:56,200 --> 00:38:59,080
Speaker 1: so that it's not just another particle or kind of stuff.

748
00:38:59,440 --> 00:39:02,040
Speaker 1: Could that war? Well, it's a cool idea, and it

749
00:39:02,080 --> 00:39:06,320
Speaker 1: does explain galaxy rotation curves, and it actually explains galaxy

750
00:39:06,440 --> 00:39:10,399
Speaker 1: rotation curves better than dark matter. There's some galaxies out

751
00:39:10,400 --> 00:39:12,640
Speaker 1: there that we still can't explain using dark matter, Like

752
00:39:12,760 --> 00:39:15,120
Speaker 1: they rotate in weird ways and we don't understand it.

753
00:39:15,160 --> 00:39:20,719
Speaker 1: And you know, but hey, galaxies are weird. They they

754
00:39:20,719 --> 00:39:26,480
Speaker 1: have their own history. No prize, sir. My theory, that's right,

755
00:39:26,600 --> 00:39:29,240
Speaker 1: My theory that the universe is just weird explains everything,

756
00:39:29,320 --> 00:39:32,880
Speaker 1: oh man, the whites and theory of everything, the whites

757
00:39:32,880 --> 00:39:36,400
Speaker 1: and theory of weirdness. But it explains the gaxy rotation

758
00:39:36,440 --> 00:39:40,120
Speaker 1: curves really nicely. But there's a big caveat there, which

759
00:39:40,120 --> 00:39:43,720
Speaker 1: is it was sort of invented to explain those curves,

760
00:39:43,800 --> 00:39:47,840
Speaker 1: like you came up with a theory to fit that data. Really,

761
00:39:47,960 --> 00:39:50,480
Speaker 1: a good test of a theory is does it explain

762
00:39:50,640 --> 00:39:54,440
Speaker 1: other data? Is that a real general principle about the universe,

763
00:39:54,480 --> 00:39:57,000
Speaker 1: something which is really deeply true? Or is it just

764
00:39:57,080 --> 00:39:59,879
Speaker 1: a mathematical tweak to this one plot, this one fig

765
00:40:00,120 --> 00:40:02,160
Speaker 1: or to make. Because if it only works to explain

766
00:40:02,239 --> 00:40:04,840
Speaker 1: one thing, it's it's kind of suspicious, right exactly, And

767
00:40:04,880 --> 00:40:07,440
Speaker 1: if it only works to explain the one thing that

768
00:40:07,520 --> 00:40:10,160
Speaker 1: motivated it, and then probably it's not a deep truth

769
00:40:10,280 --> 00:40:14,440
Speaker 1: of the universe, right a right, So maybe it doesn't work.

770
00:40:14,680 --> 00:40:16,440
Speaker 1: Can it explain some of the other things that we

771
00:40:16,480 --> 00:40:19,880
Speaker 1: know about dark matter, like the lensing and the cosmic

772
00:40:20,040 --> 00:40:24,200
Speaker 1: microwave background and the structure of the universe? A tweak

773
00:40:24,239 --> 00:40:26,800
Speaker 1: to our theory of gravity also explain all of these things?

774
00:40:26,880 --> 00:40:31,040
Speaker 1: In a word, No, it just doesn't work. No, galax

775
00:40:31,080 --> 00:40:33,360
Speaker 1: is are just weird. No galax is just weird. No,

776
00:40:33,480 --> 00:40:36,160
Speaker 1: it does not explain the cosmic microwave background, Like, it's

777
00:40:36,360 --> 00:40:40,520
Speaker 1: very difficult to explain that using anything else other than

778
00:40:40,840 --> 00:40:43,920
Speaker 1: some new kind of particle or promodial black hole or

779
00:40:43,960 --> 00:40:47,080
Speaker 1: something some new kind of stuff. You just can't explain

780
00:40:47,160 --> 00:40:49,160
Speaker 1: it using deviation and gravity because it was on a

781
00:40:49,200 --> 00:40:51,759
Speaker 1: really small scale. This is like, you know, things were

782
00:40:51,840 --> 00:40:55,799
Speaker 1: near by each other. This wasn't galactic distances interesting, And

783
00:40:55,840 --> 00:40:58,360
Speaker 1: it's very difficult to explain the structure of the universe.

784
00:40:58,520 --> 00:41:01,080
Speaker 1: And then there is one really awesome example of dark

785
00:41:01,120 --> 00:41:03,799
Speaker 1: matter that's sort of like a smoking gun that makes

786
00:41:03,800 --> 00:41:07,319
Speaker 1: it almost impossible to explain using anything but some new

787
00:41:07,400 --> 00:41:10,040
Speaker 1: kind of matter stuff, some new kind of stuff. Yeah,

788
00:41:10,280 --> 00:41:14,200
Speaker 1: and that's this Bullet cluster. There was this collision millions

789
00:41:14,200 --> 00:41:17,399
Speaker 1: and millions of years ago, far far away between two

790
00:41:17,480 --> 00:41:20,560
Speaker 1: clusters of galaxy that passed through each other. And we

791
00:41:20,600 --> 00:41:23,479
Speaker 1: thought that those clusters of galaxies they had normal matter

792
00:41:23,640 --> 00:41:26,480
Speaker 1: like stars and planets, etcetera, and then also clumps of

793
00:41:26,560 --> 00:41:29,799
Speaker 1: dark matter. So what happened is they passed through each other,

794
00:41:30,320 --> 00:41:33,280
Speaker 1: and the gas and the dust it all collided amid

795
00:41:33,320 --> 00:41:36,000
Speaker 1: big collisions and slowed down and all that stuff. But

796
00:41:36,080 --> 00:41:38,479
Speaker 1: the dark matter, it doesn't interact with the normal matter,

797
00:41:38,480 --> 00:41:40,520
Speaker 1: and it doesn't interact with itself very much at all

798
00:41:40,600 --> 00:41:43,479
Speaker 1: either because gravity is so weak, so the dark matter

799
00:41:43,520 --> 00:41:45,920
Speaker 1: is sort of passed through. So what we see when

800
00:41:45,920 --> 00:41:47,560
Speaker 1: we look up in the skies, we see like a

801
00:41:47,600 --> 00:41:50,880
Speaker 1: big blob in the center while the gas and dust interacted,

802
00:41:51,120 --> 00:41:53,799
Speaker 1: and then on either side we see the dark matter

803
00:41:53,840 --> 00:41:56,239
Speaker 1: that passed through, and we can see that because of

804
00:41:56,280 --> 00:41:58,640
Speaker 1: the gravitational lensing. Right, But doesn't it all I know,

805
00:41:58,719 --> 00:42:00,960
Speaker 1: we talked about the bullet cluster it before, but doesn't

806
00:42:01,000 --> 00:42:05,279
Speaker 1: it still just come down to gravitational lensing, Like what

807
00:42:05,400 --> 00:42:09,160
Speaker 1: if gravity can explain gravitational lensing, could that also explain

808
00:42:09,600 --> 00:42:12,200
Speaker 1: the bullet cluster that we see. It's very difficult to

809
00:42:12,239 --> 00:42:14,120
Speaker 1: explain the bullet cluster in any other way because you

810
00:42:14,160 --> 00:42:17,360
Speaker 1: need to have gravitational lensing in exactly those right spots

811
00:42:17,640 --> 00:42:21,920
Speaker 1: on opposite sides of this very obvious collision. So it's

812
00:42:21,920 --> 00:42:24,640
Speaker 1: a very nice explanation to think, oh, there's some invisible

813
00:42:24,640 --> 00:42:27,799
Speaker 1: matter that passed through and it's now sitting there distorting

814
00:42:27,800 --> 00:42:30,720
Speaker 1: the background galaxy. See, the bullet cluster is like proved

815
00:42:30,760 --> 00:42:34,920
Speaker 1: that whatever it's causing these gravitational things is mobile, like

816
00:42:35,120 --> 00:42:37,839
Speaker 1: it can move like stuff. But if it was just

817
00:42:37,880 --> 00:42:41,719
Speaker 1: a gravitational theory tweak, that wouldn't like keep going or

818
00:42:41,800 --> 00:42:44,319
Speaker 1: move or change from here to there exactly, and it

819
00:42:44,360 --> 00:42:46,920
Speaker 1: can be separated from the normal matter. It's not just

820
00:42:47,000 --> 00:42:49,760
Speaker 1: a gravitational tweak from the normal matter, right, the normal

821
00:42:49,760 --> 00:42:52,760
Speaker 1: matter was left behind in the middle. It's its own

822
00:42:52,880 --> 00:42:55,799
Speaker 1: kind of stuff. It has its own gravity. And so

823
00:42:55,880 --> 00:42:58,279
Speaker 1: that's sort of like a bullet in the brain of

824
00:42:58,320 --> 00:43:01,720
Speaker 1: the you know, non dark matter theories. The bullet cluster

825
00:43:01,840 --> 00:43:05,880
Speaker 1: is a bullet suspicious. People really took Moms sort of

826
00:43:05,960 --> 00:43:09,240
Speaker 1: seriously until then. And then when the bullet cluster was discovered,

827
00:43:09,280 --> 00:43:12,200
Speaker 1: people are like, oh, well, that's it. Dark matter is real,

828
00:43:12,640 --> 00:43:16,640
Speaker 1: and Mond is dead and never Mond. And at that

829
00:43:16,680 --> 00:43:20,040
Speaker 1: point people really didn't take months seriously. So since then,

830
00:43:20,480 --> 00:43:23,399
Speaker 1: Mond has been much more of a fringe theory. I mean,

831
00:43:23,680 --> 00:43:26,160
Speaker 1: Virlin's idea is more recent, and it's quote of cool,

832
00:43:26,480 --> 00:43:28,960
Speaker 1: but it sort of explains something that nobody really takes

833
00:43:29,000 --> 00:43:32,239
Speaker 1: seriously anymore. So it's very fringe in a way. The

834
00:43:32,280 --> 00:43:35,359
Speaker 1: bullet cluster shows you that dark matter or whatever it's

835
00:43:35,400 --> 00:43:39,640
Speaker 1: causing these gravitational distortions and footprints, is mobile like it's

836
00:43:39,760 --> 00:43:41,880
Speaker 1: it can move like stuff. It moves like a stuff

837
00:43:41,920 --> 00:43:45,880
Speaker 1: can move. Yeah, And so again it's unsatisfying because we

838
00:43:45,920 --> 00:43:48,360
Speaker 1: don't know what it is and and we've been looking

839
00:43:48,360 --> 00:43:50,480
Speaker 1: for for a while it's not like we're just like, oh,

840
00:43:50,520 --> 00:43:54,320
Speaker 1: it's some invisible stuff, let's move on. We've built dedicated

841
00:43:54,360 --> 00:43:57,239
Speaker 1: experiments to look for it. We thought several times that

842
00:43:57,360 --> 00:43:59,839
Speaker 1: we would definitely find it and then haven't seen it.

843
00:44:00,200 --> 00:44:02,359
Speaker 1: So there's definitely some tension there. It's not like dark

844
00:44:02,400 --> 00:44:04,839
Speaker 1: matter is a beautiful theory that's all wrapped up, like

845
00:44:05,160 --> 00:44:08,120
Speaker 1: we don't understand why we haven't been able to find

846
00:44:08,160 --> 00:44:11,680
Speaker 1: the dark matter yet. There's definitely something weird going on there,

847
00:44:11,840 --> 00:44:14,279
Speaker 1: and it's very healthy to think about new ideas, but

848
00:44:14,480 --> 00:44:18,000
Speaker 1: mond doesn't quite work. There is no other idea out

849
00:44:18,080 --> 00:44:21,440
Speaker 1: there that explains what we see nearly as well as

850
00:44:21,520 --> 00:44:24,480
Speaker 1: some new cold particles. I have an idea is it's

851
00:44:24,480 --> 00:44:27,840
Speaker 1: snack based. It's called Hey, maybe dark matter is weird.

852
00:44:29,880 --> 00:44:32,640
Speaker 1: It's weird, yeah, And that's why people are sort of

853
00:44:32,680 --> 00:44:35,200
Speaker 1: digging further and further into the barrel of ideas for

854
00:44:35,280 --> 00:44:37,520
Speaker 1: dark matter. People thought for a long time, Okay, dark

855
00:44:37,560 --> 00:44:41,319
Speaker 1: matter must just be some weakly interacting massive particle, some

856
00:44:41,400 --> 00:44:44,360
Speaker 1: new lava stuff, but we haven't seen it, and so

857
00:44:44,400 --> 00:44:47,000
Speaker 1: then people are well, maybe it's axions, or maybe it's

858
00:44:47,080 --> 00:44:49,919
Speaker 1: primordial black holes, or and there are some other even

859
00:44:50,080 --> 00:44:55,440
Speaker 1: crazier ideas like squirmyons, what like they're uncomfortable and social situations.

860
00:44:55,520 --> 00:45:00,239
Speaker 1: What do you mean introvertons? Yeah, no, squirmy on are

861
00:45:00,280 --> 00:45:03,279
Speaker 1: this crazy idea that you know how particles are like

862
00:45:03,440 --> 00:45:06,800
Speaker 1: excitations of quantum fields are like little bundles of energy

863
00:45:06,800 --> 00:45:09,960
Speaker 1: in a quantum field. People think, well, maybe not all

864
00:45:10,120 --> 00:45:12,480
Speaker 1: energy and quantum fields are particles. Maybe some of them

865
00:45:12,520 --> 00:45:15,760
Speaker 1: are like more distributed or spread out in weird ways.

866
00:45:15,760 --> 00:45:18,640
Speaker 1: And they found that you can like tangle up quantum

867
00:45:18,680 --> 00:45:21,520
Speaker 1: fields in these weird ways, like make nots of them,

868
00:45:21,800 --> 00:45:24,439
Speaker 1: and that's what they call squirmyons. And it's not could

869
00:45:24,480 --> 00:45:27,880
Speaker 1: like it could create gravity. Yeah, because any energy density

870
00:45:27,920 --> 00:45:32,040
Speaker 1: creates gravity. Well, we'll have to dig into that for

871
00:45:32,120 --> 00:45:36,680
Speaker 1: another episode. Sounds pretty for sure. So there's lots of

872
00:45:36,680 --> 00:45:38,799
Speaker 1: ideas the whole spectrum, right, dark matter is not just

873
00:45:38,960 --> 00:45:42,799
Speaker 1: one idea, the sort of spectrum of ideas all satisfied

874
00:45:42,840 --> 00:45:45,920
Speaker 1: the condition that it's some new kind of cold object.

875
00:45:46,400 --> 00:45:48,680
Speaker 1: But what that object is. It could be one particle,

876
00:45:48,719 --> 00:45:51,880
Speaker 1: could be many kinds of particles. It could be black holes,

877
00:45:51,960 --> 00:45:54,279
Speaker 1: it could be squirmyons, it could be something else we

878
00:45:54,320 --> 00:45:57,240
Speaker 1: haven't even thought of yet. Whatever, it is. We're pretty

879
00:45:57,280 --> 00:46:00,160
Speaker 1: sure it's stuff. It's something that has gravity stuff when

880
00:46:00,160 --> 00:46:02,400
Speaker 1: it's there, that's right. But I mean it's really interesting

881
00:46:02,440 --> 00:46:04,440
Speaker 1: because I feel like we've known dark matters is there

882
00:46:04,480 --> 00:46:06,279
Speaker 1: for a while now, and we just can't seem to

883
00:46:06,280 --> 00:46:08,200
Speaker 1: crack it. We can't seem to find it keeps um

884
00:46:08,200 --> 00:46:11,160
Speaker 1: eluding us, you know, like it just keeps on hiding

885
00:46:11,200 --> 00:46:13,799
Speaker 1: there and not letting us know what it is. That's right,

886
00:46:13,840 --> 00:46:15,440
Speaker 1: But we don't know how long the story is. You know,

887
00:46:15,480 --> 00:46:17,880
Speaker 1: we were looking for the Higgs boson for fifty years

888
00:46:18,000 --> 00:46:20,319
Speaker 1: and then we found it. We were looking for the

889
00:46:20,360 --> 00:46:23,040
Speaker 1: top cork for twenty years before we found it. A

890
00:46:23,040 --> 00:46:25,000
Speaker 1: lot of those things. People thought, oh, we'll find this

891
00:46:25,040 --> 00:46:27,400
Speaker 1: in the next year two and then they were confused

892
00:46:27,400 --> 00:46:29,680
Speaker 1: and disappointed to not discover it soon. But you know,

893
00:46:29,760 --> 00:46:32,239
Speaker 1: eventually we got there and we we figured it out.

894
00:46:32,280 --> 00:46:35,359
Speaker 1: So maybe we're just five years away from discovering dark matter,

895
00:46:35,440 --> 00:46:37,400
Speaker 1: or maybe it's going to be another hundred. Maybe we

896
00:46:37,440 --> 00:46:40,000
Speaker 1: need a new crazy idea for what dark matter is.

897
00:46:40,040 --> 00:46:43,359
Speaker 1: But dark matter, I'm pretty sure is so all those

898
00:46:43,400 --> 00:46:47,800
Speaker 1: physicists squirming around relax. Maybe dark matter is in our future.

899
00:46:47,880 --> 00:46:50,239
Speaker 1: That's right. I certainly hope it is. It would be fascinating.

900
00:46:50,280 --> 00:46:52,879
Speaker 1: And remember that it's most of the stuff out there

901
00:46:52,880 --> 00:46:56,319
Speaker 1: in the universe. Like, what a crazy opportunity to learn

902
00:46:56,360 --> 00:46:59,040
Speaker 1: about the way the universe works, you know, to know

903
00:46:59,120 --> 00:47:01,359
Speaker 1: that of the stuff out there in the universe has

904
00:47:01,400 --> 00:47:03,840
Speaker 1: been hidden from us. The day we crack that open

905
00:47:03,920 --> 00:47:05,759
Speaker 1: and get to learn about it, like, it could have

906
00:47:05,800 --> 00:47:09,719
Speaker 1: incredibly complex structure, it could have interactions and biology and

907
00:47:09,800 --> 00:47:12,600
Speaker 1: chemistry and all sorts of crazy stuff. Movest of the

908
00:47:12,600 --> 00:47:14,960
Speaker 1: stuff out there in the universe we haven't yet gotten

909
00:47:14,960 --> 00:47:17,640
Speaker 1: to play with, and so we're eager, we're desperate to

910
00:47:17,680 --> 00:47:19,600
Speaker 1: figure out what this stuff is. Yeah, because if you're

911
00:47:19,600 --> 00:47:22,200
Speaker 1: the scientist that discovers what dark matter is, I mean,

912
00:47:22,320 --> 00:47:25,399
Speaker 1: that's like a lot of three cred you know. It's

913
00:47:25,440 --> 00:47:29,360
Speaker 1: like you could say that you discovered eight eight percent

914
00:47:29,440 --> 00:47:31,440
Speaker 1: of everything in the universe. I think they would have

915
00:47:31,480 --> 00:47:33,719
Speaker 1: to give you five Nobel Prizes, you know, just for

916
00:47:33,719 --> 00:47:35,840
Speaker 1: that one discovery. They have to give you eighty percent

917
00:47:35,880 --> 00:47:38,600
Speaker 1: of all the Nobel prizes. I think, Yeah, yeah, there

918
00:47:38,600 --> 00:47:40,719
Speaker 1: you go. You get all the Nobel Prizes for the

919
00:47:40,719 --> 00:47:43,560
Speaker 1: next four hundred years, just to balance it out. Yeah,

920
00:47:43,640 --> 00:47:45,560
Speaker 1: So it's a big question, and who knows, maybe one

921
00:47:45,600 --> 00:47:48,279
Speaker 1: of our listeners will be the one who discovers it.

922
00:47:48,360 --> 00:47:49,879
Speaker 1: That's right, It could be you out there, it could

923
00:47:49,880 --> 00:47:51,960
Speaker 1: be your kids out there. What we definitely need to

924
00:47:51,960 --> 00:47:53,759
Speaker 1: do or keep our minds open and come up with

925
00:47:53,800 --> 00:47:57,000
Speaker 1: new ideas for what dark matter is really cool? All right, Well,

926
00:47:57,320 --> 00:48:00,440
Speaker 1: we hope you enjoyed that view into this story is

927
00:48:00,520 --> 00:48:02,520
Speaker 1: dark matter and how we know it's there and how

928
00:48:02,680 --> 00:48:06,640
Speaker 1: we know it's not just a weird fluke of gravitational equations.

929
00:48:06,800 --> 00:48:17,200
Speaker 1: Thanks for tuning in, See you next time. Thanks for listening,

930
00:48:17,280 --> 00:48:20,000
Speaker 1: and remember that Daniel and Jorge Explain the Universe is

931
00:48:20,000 --> 00:48:23,440
Speaker 1: a production of I Heart Radio. For more podcast For

932
00:48:23,520 --> 00:48:27,279
Speaker 1: my heart Radio, visit the i heart Radio app, Apple Podcasts,

933
00:48:27,400 --> 00:48:29,760
Speaker 1: or wherever you listen to your favorite shows.