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Speaker 3: I'm David Ego from the podcast Inner Cosmos, which recently

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Speaker 3: three pound universe in our heads. Join me weekly to

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Speaker 1: He Jorge, I have an idea for our Daniel and

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Speaker 1: Jorge explain the universe food truck.

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Speaker 5: Oh nice, wait, are we actually doing that? I thought

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Speaker 5: it was a joke.

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Speaker 1: Well it was a joke, but then our listener Tim

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Speaker 1: Lazarov wrote in to ask when our food truck is

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Speaker 1: going to be in his neighborhood.

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Speaker 5: Maybe should be more like a food spaceship that would

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Speaker 5: be more appropriate.

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Speaker 1: Well, that goes perfectly well with my idea. You see,

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Speaker 1: normal food trucks serve drinks, right fluids to wash down

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Speaker 1: their tasty treats. But our food spaceship should serve super

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Speaker 1: fluids like zero viscosity beverages.

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Speaker 5: Nice so they go down easier. Or do they have

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Speaker 5: both Einstein condensation on the outside.

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Speaker 1: I'm thinking we should test it on some undergrads, you know,

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Speaker 1: make sure it's safe before we sell it to the public.

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Speaker 5: I'm sure the FDA is all over that.

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Speaker 1: I don't think they have a physics food division yet.

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Speaker 5: That's the PDA Physics and Drugs Administration.

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Speaker 6: Hi.

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Speaker 5: I am Jorge. I'm a cartoonist and the co author

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Speaker 5: of Frequently Asked Questions about the Universe.

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Speaker 1: Hi. I'm Daniel. I'm a physics professor and a particle

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Speaker 1: physicist who does research at CERN, and every time I'm

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Speaker 1: in a lab, I'm always tempted to.

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Speaker 5: Taste everything that sounds like a terrible idea, Daniel, especially

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Speaker 5: if you visit a virology lab.

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Speaker 1: Yeah, but you know they got like weird glowing goo.

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Speaker 1: You're like, hmm, I wonder what flavor that is. I'm

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Speaker 1: never gonna do it, of course, I hope, but you know,

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Speaker 1: the curious mind wonders.

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Speaker 5: Right, Remind me never to invite you to my lab,

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Speaker 5: otherwise you'll be licking everything like a dog.

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Speaker 1: Or a two year old like that kid in the

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Speaker 1: movie that licks the flagpole and wonders if his tongue

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Speaker 1: is really going to stick to it.

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Speaker 5: M we should get into the physics of a Christmas story.

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Speaker 1: We'll shoot your eyes out.

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Speaker 5: But welcome to our podcast, Dan Niel and Jorge Explain

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Speaker 5: the Universe, a production of iHeartRadio.

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Speaker 1: In which we invite you to taste the entire universe

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Speaker 1: to enjoy the flavor of knowledge as well as ignorance,

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Speaker 1: to take a bite out of everything that we do

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Speaker 1: and do not know about the universe. We don't shy

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Speaker 1: away from the big mysteries on this podcast. We talk

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Speaker 1: about the smallest things, the medium sized things, and even

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Speaker 1: the biggest things, and we attack all of them and

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Speaker 1: try to explain them to you.

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Speaker 5: Yeah, it is a delicious looking universe, like a giant,

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Speaker 5: cosmic buffet of amazing ideas and incredible phenomena that are

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Speaker 5: there for us to dig into and fill our bellies

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Speaker 5: with amazing knowledge.

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Speaker 1: Yeah, and if you're not a curious person, then you

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Speaker 1: wouldn't take a bite of these weird things. And I

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Speaker 1: think that's why when I'm in some kind of laboratory

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Speaker 1: and I see something weird bubbling in a flask and

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Speaker 1: I wonder, hmm, I wonder if that would make a

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Speaker 1: good soda for our food truck. It's that same curiosity

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Speaker 1: that inspires me to try to take a bite out

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Speaker 1: of the whole universe because I want to know. I

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Speaker 1: want to understand. It's not enough to just say I

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Speaker 1: bet that green bubbling thing tastes something like lemon lime soda.

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Speaker 1: I want to actually know the truth.

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Speaker 5: I think there are easier ways to find out what

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Speaker 5: something is, Daniel, rather than putting it in your mouth

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Speaker 5: and in your body. Have you tried asking what it is?

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Speaker 5: It seems like the polite thing to do, But.

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Speaker 1: Then how would they know, right if they haven't tasted it.

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Speaker 5: Maybe some questions are not meant to be answered, What like,

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Speaker 5: are you curious about how cyanide tastes.

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Speaker 1: I am curious. Actually, you know, I like almond pastries

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Speaker 1: and so hey, maybe you know a nice cyanide after

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Speaker 1: flavor is not the worst thing in the world. But yeah,

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Speaker 1: I'm curious about all of this stuff, even the stuff

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Speaker 1: that might kill you to find out the answer. It's

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Speaker 1: just this deep desire to know these truths.

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Speaker 5: Well, speaking of dark matters like tasting poison, there are

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Speaker 5: amazing mysteries out there, including one that is maybe one

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Speaker 5: of the biggest mysteries in the universe. At least it's

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Speaker 5: the second biggest mystery in the universe by percentage wise.

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Speaker 1: Right, that's right. If the universe was laid out as

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Speaker 1: a buffet, most of it would be dark energy, but

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Speaker 1: a huge, heaping pile of it would be dark matter.

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Speaker 1: Most of the actual stuff in the universe, the matter,

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Speaker 1: the things, the bits and pieces that move around in

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Speaker 1: our universe, are not the things that make up me

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Speaker 1: and you and weird beakers of bubbling green goo in

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Speaker 1: chemistry laboratories. It's something else, something different, something we do

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Speaker 1: not yet understand. But we have a cool name for it.

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Speaker 5: It's right, we have a cool name for it. It's

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Speaker 5: dark matter, and that is an interesting analogy, Daniel. I

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Speaker 5: guess the universe is like a giant buffet, and five

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Speaker 5: percent of it is like regular food, right, chicken and

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Speaker 5: bread and pasta salad, And about twenty seven percent of

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Speaker 5: that buffet is a big giant mystery, some kind of

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Speaker 5: weird dark stuff. And I guess you would be right

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Speaker 5: in there tiling it on on your plate.

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Speaker 1: Yeah, I don't know if I'll go back for seconds.

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Speaker 1: You know, I got to try the first serving, but yeah,

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Speaker 1: serve me up some dark matter. I want to know

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Speaker 1: what it is. Does it, in the end just taste

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Speaker 1: like chicken?

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Speaker 5: Would it taste? I guess it would just go through

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Speaker 5: your tongue, wouldn't it.

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Speaker 1: That's right. Dark matter sounds like something black and heavy,

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Speaker 1: but actually it's invisible and intangible. Dark matter would pass

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Speaker 1: right through you like a cloud of neutrinos, because we

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Speaker 1: don't think that it interacts with normal matter in any

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Speaker 1: way other than with gravity, and gravity is a very

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Speaker 1: very weak force, so you couldn't even pick up a

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Speaker 1: spoon of dark matter. If you had like a blob

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Speaker 1: of dark matter and you dropped it, it would fall

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Speaker 1: to the center of the Earth.

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Speaker 5: Right, And we don't even know if it is matter.

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Speaker 5: We don't even know if it is stuff. All we

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Speaker 5: know about it is its effect on the rest of

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Speaker 5: the universe and the rest of the stars and galaxies

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Speaker 5: out there that we can see.

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Speaker 1: That's right. We have never confirmed the particle nature of

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Speaker 1: dark matter. We don't even really know one hundred percent

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Speaker 1: that it's stuff. And we've talked about it on the

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Speaker 1: podcast a lot of times, and we've said that we

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Speaker 1: are pretty sure it's matter, but there are some questions

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Speaker 1: that remain. There are some things that we see out

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Speaker 1: there in the universe that the idea that dark matter

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Speaker 1: is stuff is some kind of invisible new matter in

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Speaker 1: the universe doesn't quite explain. And there are a few

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Speaker 1: other ideas, different hypotheses to try to explain it. And

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Speaker 1: I know that it's one of the favorite pastime of

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Speaker 1: our listeners because they're always writing the emails about maybe

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Speaker 1: dark matter is actually this other thing, or what if

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Speaker 1: dark matter it could be something else totally different. It

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Speaker 1: is one of the biggest, most accessible mysteries in the universe.

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Speaker 5: That's right. Maybe it is a giant tray of uh

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Speaker 5: in some kind of cosmic buffet for some giant beings.

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Speaker 1: Perhaps, Yeah, maybe it's just like weird pasta instead of squiddying,

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Speaker 1: because they put something else into it to make it

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Speaker 1: like really dark or invisible.

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Speaker 5: But I guess what you mean, right.

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Speaker 1: Yeah, if there's some kind of animal that sprays something

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Speaker 1: that makes it invisible, maybe they've just inserted that into

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Speaker 1: the dark matter pasta.

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Speaker 5: Well, hopefully it's more like the dessert of the universe,

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Speaker 5: because that'd be pretty neat, right. A third of the

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Speaker 5: universe is just desserts.

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Speaker 1: Is that tell us about your diet? Or Hey, are

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Speaker 1: you like eighty percent desserts?

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Speaker 5: Sure? Why not? I guess it all depends on your perspective.

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Speaker 5: Vegetables can be dessert, right.

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Speaker 1: Sure, yeah, I guess so. I like a nice zucchini bread.

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Speaker 5: Yeah, it's that technically whatever you eat at the end, right.

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Speaker 1: Sounds good. Well, I'm hoping that we can gobble up

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Speaker 1: the mystery of dark matter one day, but until then,

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Speaker 1: we have to think carefully about what we have seen,

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Speaker 1: what we know, what we can explain, what we can't explain,

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Speaker 1: and what new ideas we might need to tell a

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Speaker 1: complete and true story about everything that's happening out there

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Speaker 1: in the universe.

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Speaker 5: Yeah, it is an ongoing debate about what dark matter is,

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Speaker 5: and it's an ongoing exploration of what it could be.

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Speaker 5: So today we'll be talking about one possible idea for

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Speaker 5: dark matter. So today on the program, we'll be tackling

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Speaker 5: the question could dark matter be a super fluid?

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Speaker 1: And if so, is it sparkling?

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Speaker 5: And will it kill you? I guess if you drink it?

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Speaker 1: Question number two? Right? First, I want to know if

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Speaker 1: it's carbonated. Then question number two is can I survive

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Speaker 1: drinking it?

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Speaker 5: Well, it dissolve all the carbon in your body. As

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Speaker 5: a second question, I guess you would want to know

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Speaker 5: before you drink anything, unless you're Daniel Whites It.

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Speaker 1: Yeah, And it's a really interesting question whether dark matter

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Speaker 1: is a super fluid. And you might wonder like, why

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Speaker 1: do we care? Why do we think it might be

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Speaker 1: a super fluid. And for all the successes that dark

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Speaker 1: matter has had in explaining the large scale structure of

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Speaker 1: the universe and gravitational lensing and the wiggles we see

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Speaker 1: in the cosmic microwave background radiation, we'll talk about it

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Speaker 1: in a minute, but there are some things that dark matter,

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Speaker 1: as a theory of some weird invisible particle, really struggles

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Speaker 1: to explain in our universe it needs a little bit

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Speaker 1: of help.

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Speaker 5: Yeah, and I feel like we maybe skipped the question here,

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Speaker 5: Like I feel like we never even tackle the question

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Speaker 5: could dark matter be a fluid? Like do we even

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Speaker 5: know if it could be a fluid or a solid

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Speaker 5: or a gas.

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Speaker 6: Yeah.

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Speaker 1: Well, actually, dark matter already we think is kind of

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Speaker 1: a collisionless fluid, sort of like an ideal gas. You know,

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Speaker 1: we think about it as these particles flying around in

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Speaker 1: the universe, not interacting with each other at all, because again,

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Speaker 1: the only interactions we think it has is gravity. Gravity

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Speaker 1: between particles is basically zero. So already we think of

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Speaker 1: dark matter as sort of like a collisionless fluid or

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Speaker 1: an ideal gas. So here we're talking about it having

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Speaker 1: like special properties from being a super fluid.

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Speaker 5: Like a superhero. But it shouldn't be like a supergas then.

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Speaker 1: Yeah, exactly, Maybe it gets bitten by a radioactive spider

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Speaker 1: and then turns into a superfluid or supergas.

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Speaker 5: Yeah, radioactive fluid spider. I guess it would have to be.

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Speaker 1: The marvel theory of the universe.

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Speaker 5: Well, as usual, we were wondering how many people out

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Speaker 5: there had considered this question whether dark matter could be

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Speaker 5: a superfluid. So Daniel went out there into the wilds

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Speaker 5: of the internet, or maybe the campus of UC Irvine,

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Speaker 5: which one this time, Daniel.

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Speaker 1: These are Internet answers, So thanks very much to everybody

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Speaker 1: who participates in these and waits patiently for us to

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Speaker 1: get to the episode. If you'd like to participate for

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Speaker 1: future episodes, please don't be shy. Write to us two

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Speaker 1: questions at Danielandjorge dot com.

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Speaker 5: So think about it for a second. Do you think

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Speaker 5: dark matter could be a super fluid? Here's what people

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Speaker 5: had to say.

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Speaker 7: Well, I wish I knew what a superfluid was, because

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Speaker 7: that sounds like a really awesome thing to get to know.

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Speaker 7: The dark matter could be a lot of different things

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Speaker 7: still at this point. So sure, it could be a superfluid.

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Speaker 7: It could be a great soft drink that sadly just

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Speaker 7: passes right through your body.

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Speaker 8: I don't really think that's true because the other superfluids

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Speaker 8: that we've created are all made out of quarks. They're

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Speaker 8: just in a different arrangement, and I don't think quarks

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Speaker 8: can you display the behaviors that dark matter does. So no,

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Speaker 8: I don't think that dark matter is superloid but.

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Speaker 1: Who knows, Well, what's a super fluid.

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Speaker 9: I believe that's material that doesn't lose energy when it's moving,

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Speaker 9: So it sounds like dark meta would really hit that

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Speaker 9: point because it doesn't even interfere with itself. On the

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Speaker 9: other hand, we know that dark meta is impacted by gravity,

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Speaker 9: so that would speak against it. So I'm not really sure.

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Speaker 9: But if I would have to make a bet, I

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Speaker 9: would say, yeah, it's a superfluid.

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Speaker 10: I don't see how can anything out in space be

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Speaker 10: considered a fluid given how low density it is, and

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Speaker 10: if it isn't a fluid, it could be a superfluid

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Speaker 10: no idea.

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Speaker 6: That's fascinating. I would not have thought dark matter was

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Speaker 6: dense enough to be a fluid in the sense that

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Speaker 6: we understand it. My understanding that dark matter is going

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Speaker 6: to be as diffuse as regular matter in its distribution

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Speaker 6: through a nearly infinite universe, so that it's going to

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Speaker 6: behave like a gas. I would think, if.

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Speaker 11: I remember correctly, a super fluid doesn't is a fluid

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Speaker 11: fluid without viscosity. I think it was viscosity, And well,

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Speaker 11: we know dark matter is supposed to interact with matter

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Speaker 11: only through gravity. But I suppose if it interacts any

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Speaker 11: through gravity, that implies some form of attraction, which means

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Speaker 11: if we regard it as a fluid, it must have

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Speaker 11: some sort of viscosity, which, if I remember the definition

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Speaker 11: of a super fluid correctly, means it can't.

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Speaker 1: Be a super fluid. Sure, I guess it could be anything.

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Speaker 12: We really don't know much about dark matter other than

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Speaker 12: it exists and it has gravity, So why not? Could

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Speaker 12: be could be super fluid, could be, could be anything?

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Speaker 5: Really interesting answer is some skepticism. Some people were like,

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Speaker 5: and I don't think.

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Speaker 1: So, this one sounds weird of people. I think the

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Speaker 1: idea of having like a fluid out in space sounds weird.

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Speaker 1: People think of space as like cold and mostly empty,

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Speaker 1: maybe filled with tiny little crystals or particles flying around.

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Speaker 1: But like a fluid is a weird thing to think

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Speaker 1: about having in space.

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Speaker 5: Right, And it seems like a lot of people are like,

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Speaker 5: maybe it could be a fluid, but a super fluid.

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Speaker 5: I don't know if I would give it, you know,

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Speaker 5: supernatural powers.

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Speaker 1: Yeah, well, at least one guy is ready to taste it, though,

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Speaker 1: you know he's thinking about super soft drinks.

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Speaker 5: Hmmm, interesting super soda, super dark soda exactly.

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Speaker 1: It's very massive.

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Speaker 5: It's like Coca cola dark. Ooh, Coke, give us a call.

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Speaker 5: We got ideas special dark recipe. Yeah, but a lot

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Speaker 5: of people didn't seem to know what even a super

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Speaker 5: fluid is. I guess that's not a common word even

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Speaker 5: I'm not sure what it quite means.

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Speaker 1: Yeah, superfluids are not the kind of thing you have

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Speaker 1: experienced with that you don't see them in your everyday life.

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Speaker 1: The river that runs through the park in the middle

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Speaker 1: of your town doesn't ever become a super fluid. You

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Speaker 1: don't make superfluids in your kitchen. They're like a weird

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Speaker 1: quantum state of matter that we only recently even we're

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Speaker 1: sure could exist. And so it's sort of a new

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Speaker 1: theoretical idea, and whenever that happens, people have fun applying it.

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Speaker 1: They're like, Ooh, this is new and cool. Maybe this

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Speaker 1: works also over here in this different part of physics

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Speaker 1: where there's something we don't understand. We have a new hammer,

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Speaker 1: So let's see what else could be a nail.

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Speaker 5: Yeah, it seems like maybe dark matter being a superfluid

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Speaker 5: could maybe explain some of the things we can't quite

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Speaker 5: figure out about it. And so Daniel, let's step people

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Speaker 5: through this. First of all, I guess, let's recap what

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Speaker 5: dark matter is and what is it that we don't

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Speaker 5: understand about it that is making us consider this idea.

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Speaker 1: So we think that the universe has a bunch of

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Speaker 1: invisible matter in it because we see a lot of

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Speaker 1: gravity out there in the universe that we can't explain

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Speaker 1: from visible matter. You know, we know that stars are

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Speaker 1: huge balls of hydrogen and they have a lot of mass,

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Speaker 1: and so they have a lot of gravity. And the

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Speaker 1: Earth spins around the Sun, for example, because of the

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Speaker 1: mass of all that gravity. But if you look at

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Speaker 1: a galaxy and you add up all the mass from

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Speaker 1: all the stars that you can see, you can't explain

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Speaker 1: all the gravity that's happening in the galaxy. Like the

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Speaker 1: galaxy is spinning, like all galaxies do. That spinning would

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Speaker 1: tend to toss stars into outer space, the way like

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Speaker 1: ping pong balls on a Merry go round. If you spin,

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Speaker 1: it would toss those ping pong balls out past the

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Speaker 1: merry go round. But the gravity of the galaxy keeps

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Speaker 1: those stars in place. That's why this Milky Way is

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Speaker 1: not just like throwing all of our stars away. But

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Speaker 1: the galaxies are spinning really really fast, and in order

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Speaker 1: to hold them in place, they need more gravity than

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Speaker 1: we can account for. The gravity from the stars we

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Speaker 1: can see doesn't give us enough gravity to hold the

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Speaker 1: galaxy together. And on a bigger scale, we also need

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Speaker 1: to hold galaxy clusters together. Galaxy clusters are big groups

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Speaker 1: of galaxies, and we don't think those galaxies seem to

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Speaker 1: have enough mass to hold themselves together. Galaxy clusters are

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Speaker 1: also spinning. But if you add a bunch of invisible

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Speaker 1: mass to the galaxies, then it all works. Because it's invisible,

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Speaker 1: it explains why you can't see it, and it's new matter,

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Speaker 1: so it adds more gravity, and so it solves those

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Speaker 1: problems if you add this weird new invisible stuff to

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Speaker 1: the universe. The weirdest thing about it, though, is that

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Speaker 1: you need much more dark matter than visible stuff. It's

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Speaker 1: not like you just add a little sprinkling of dark matter.

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Speaker 1: You need to take every star and add five stars

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Speaker 1: worth of dark matter to explain all the missing gravity.

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Speaker 5: Yeah, it's almost like dark matter is kind of like

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Speaker 5: the missing piece and what we see of the universe

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Speaker 5: right and the way the galaxies stick together and the

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Speaker 5: galaxy clusters stick together. They stick together more than they

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Speaker 5: should given what we can see in them. And so

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Speaker 5: one solution is that maybe there's invisible stuff out there

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Speaker 5: that's holding it together.

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Speaker 1: Yeah, and this is the kind of thing we're always

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Speaker 1: trying to do, is reconcile everything we see. We think

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Speaker 1: we understand how gravity works. Let's check it. Let's make

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Speaker 1: sure that our explanation makes sense, that it works for

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Speaker 1: this scenario. And that's how we discovered, oh my gosh,

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Speaker 1: it doesn't. And that was the clue that maybe there

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Speaker 1: was something else going on, or there was something else

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Speaker 1: new out there. But before you believe that, just like

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Speaker 1: crazy new idea that the universe is filled with a

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Speaker 1: huge amount of invisible stuff you just happened and never

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Speaker 1: noticed before, you want other pieces of evidence. And so

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Speaker 1: we have other clues that dark matter might be real.

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Speaker 1: We see it affecting the way light moves through the universe,

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Speaker 1: because if it has mass, it changes the curvature of space,

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Speaker 1: and so it can lens light. We see that it

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Speaker 1: existed in the very early universe because it affected the

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Speaker 1: wiggles in the cosmic microwave background radiation. These photons from

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Speaker 1: the plasma that filled the universe very very early on,

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Speaker 1: and we also know that it affected the whole way

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Speaker 1: that the universe formed, the large scale structure of the universe.

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Speaker 1: Galaxies we think wouldn't even exist if dark matter hadn't

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Speaker 1: created little gravitational wells to pull stars into. So it

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Speaker 1: mostly all hangs together into a very nice.

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Speaker 5: Story, right, But it's kind of interesting. I guess it's

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Speaker 5: a story we made up assuming that what we know

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Speaker 5: of the rest of the universe is true. Right, Like,

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Speaker 5: if we assume that the laws of fiss work the

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Speaker 5: way we think they do, then you sort of need

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Speaker 5: this invisible matter to just make what we see make sense.

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Speaker 5: But that's only assuming that we're right about the laws

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Speaker 5: of physics.

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Speaker 1: Yeah, that's saying gravity works a certain way, and so

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Speaker 1: in order to explain this missing gravity, we need more mass.

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Speaker 1: But you're right, there are other ideas. People have also thought, well,

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Speaker 1: maybe gravity doesn't work the way that we thought. Maybe

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Speaker 1: there isn't any missing gravity. It's just signs that our

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Speaker 1: theory of gravity is wrong. And people have tried to

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Speaker 1: modify the theory of gravity to explain what we see,

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Speaker 1: and this is called mond modified Newtonian dynamics. The theory

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Speaker 1: says that instead of gravity going like one over distance

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Speaker 1: square the way Newton said, there's another factor there that

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Speaker 1: when things have very low accelerations, gravity is a little

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Speaker 1: bit different. It gets a little stronger. So if you

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Speaker 1: tweak gravity in just this way, you can also explain

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Speaker 1: how galaxies rotate without using dark matter.

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Speaker 5: That's really interesting. So it could be that dark matter

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Speaker 5: is not dark matter at all, Like maybe we just

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Speaker 5: have the laws of physics a little bit wrong. But

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Speaker 5: does that explain everything about the way the galaxies stick

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Speaker 5: together and even the gravitational lensing.

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Speaker 1: No, So mind this alternative theory gravity does in fact

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Speaker 1: a better job at explaining how galaxies rotate than dark

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Speaker 1: matter does. There's some things about galaxy rotations that dark

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Speaker 1: matter just can't seem to get right, but it doesn't

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Speaker 1: explain everything else that dark matter does, Like mind does

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Speaker 1: not do a good job of describing how galaxy clusters

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Speaker 1: rotate and spin around themselves, and it's much more difficult

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Speaker 1: for it to explain like the cosmic microwave background and

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Speaker 1: lensing and all sorts of other very strong evidence for

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Speaker 1: dark matter. So mind is sort of a nice idea.

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Speaker 1: It can explain one thing actually better than dark matter can.

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Speaker 1: But dark matter is sort of like a stronger idea

439
00:20:41,960 --> 00:20:42,879
Speaker 1: across the board.

440
00:20:43,480 --> 00:20:45,600
Speaker 5: But neither of them, I guess, is perfect. And let's

441
00:20:45,640 --> 00:20:47,520
Speaker 5: maybe dig into that a little bit, like what is

442
00:20:47,560 --> 00:20:50,280
Speaker 5: it about the idea that dark matter is invisible stuff?

443
00:20:50,280 --> 00:20:52,280
Speaker 5: That doesn't explain what we see out there.

444
00:20:52,320 --> 00:20:54,879
Speaker 1: So by now we've seen a lot of galaxies, and

445
00:20:54,920 --> 00:20:57,200
Speaker 1: what we try to do is understand, like how much

446
00:20:57,280 --> 00:20:59,920
Speaker 1: dark matter is in a galaxy versus how much normal matter,

447
00:21:00,080 --> 00:21:03,000
Speaker 1: and is that common across galaxies? Like do all galaxies

448
00:21:03,040 --> 00:21:05,120
Speaker 1: have the same amount of dark matter and the same

449
00:21:05,160 --> 00:21:07,800
Speaker 1: amount of normal matter? And we also try to understand

450
00:21:08,000 --> 00:21:10,440
Speaker 1: how that could have happened. You know, if dark matter

451
00:21:10,560 --> 00:21:13,679
Speaker 1: is this weird particle, this new heavy, invisible thing, then

452
00:21:13,720 --> 00:21:15,960
Speaker 1: it would have clustered together and we can make models

453
00:21:15,960 --> 00:21:18,399
Speaker 1: for how that would have happened in formed galaxies. We

454
00:21:18,440 --> 00:21:20,720
Speaker 1: look out into the universe. The galaxies we see don't

455
00:21:20,760 --> 00:21:23,560
Speaker 1: really line up with what we expect for dark matter.

456
00:21:23,720 --> 00:21:26,359
Speaker 1: So one thing specifically we look at is a relationship

457
00:21:26,359 --> 00:21:29,360
Speaker 1: between how bright the galaxies are and how fast they

458
00:21:29,400 --> 00:21:32,440
Speaker 1: are spinning. How bright they are is really interesting because

459
00:21:32,440 --> 00:21:34,280
Speaker 1: it tells us like how much normal matter is there,

460
00:21:34,280 --> 00:21:37,679
Speaker 1: how many stars, how fast they're spinning, should tell us

461
00:21:37,720 --> 00:21:40,400
Speaker 1: something about how much dark matter there is in the galaxy.

462
00:21:40,520 --> 00:21:42,399
Speaker 1: And if you do a bunch of simulations, then you

463
00:21:42,440 --> 00:21:45,760
Speaker 1: expect like a loose relationship there. You expect like some

464
00:21:45,920 --> 00:21:47,720
Speaker 1: galaxies to have a lot of dark matter and some

465
00:21:47,840 --> 00:21:49,399
Speaker 1: to have a little bit, but there to be a

466
00:21:49,400 --> 00:21:51,840
Speaker 1: lot of variation. What we see when we look at

467
00:21:51,840 --> 00:21:54,960
Speaker 1: these galaxies, though, is that there's a very very tight relationship.

468
00:21:55,160 --> 00:21:58,560
Speaker 1: It's like almost no variation. Like the amount of stars

469
00:21:58,600 --> 00:22:00,200
Speaker 1: in a galaxy and the amount of dark man in

470
00:22:00,240 --> 00:22:03,439
Speaker 1: the galaxy has a very very close relationship, which we

471
00:22:03,440 --> 00:22:05,840
Speaker 1: think is weird and we can't explain with our models.

472
00:22:06,119 --> 00:22:08,200
Speaker 5: You mean, like when you look at the galaxies out

473
00:22:08,200 --> 00:22:10,840
Speaker 5: there in the universe, they almost have the same proportion

474
00:22:10,960 --> 00:22:13,000
Speaker 5: of regular matter in dark matter. I think that's what

475
00:22:13,000 --> 00:22:15,080
Speaker 5: they're saying, right, Like, there aren't galaxies out there with

476
00:22:15,119 --> 00:22:16,919
Speaker 5: a lot of dark matter, and there aren't a lot

477
00:22:16,960 --> 00:22:19,080
Speaker 5: of galaxies with a little bit of dark matter, which

478
00:22:19,240 --> 00:22:21,399
Speaker 5: is weird. But I guess to me, it's weird that

479
00:22:21,400 --> 00:22:23,480
Speaker 5: you would think it's weird. Why wouldn't they all beast

480
00:22:23,520 --> 00:22:25,040
Speaker 5: sort of the same that they were all made in

481
00:22:25,080 --> 00:22:25,880
Speaker 5: the Big Bang.

482
00:22:25,720 --> 00:22:28,600
Speaker 1: You know, because there's a random element here, right, Like

483
00:22:28,840 --> 00:22:32,320
Speaker 1: how do galaxies form? Anyway, it comes from a quantum

484
00:22:32,400 --> 00:22:35,800
Speaker 1: fluctuation in the initial seeds of the universe that gave

485
00:22:35,840 --> 00:22:39,159
Speaker 1: you a slight over density in the dark matter that

486
00:22:39,240 --> 00:22:42,160
Speaker 1: pulled together a little well and then grab some stuff.

487
00:22:42,600 --> 00:22:45,400
Speaker 1: And you know, we do expect some relationship. We expect

488
00:22:45,440 --> 00:22:47,399
Speaker 1: there to be a relationship between the amount of matter

489
00:22:47,440 --> 00:22:49,600
Speaker 1: and the amount of dark matter, because in the beginning

490
00:22:49,640 --> 00:22:52,359
Speaker 1: we think this stuff is mostly evenly spread out, but

491
00:22:52,400 --> 00:22:55,440
Speaker 1: we also expect some variation. And when they do simulations

492
00:22:55,480 --> 00:22:57,719
Speaker 1: to try to predict what kind of variation we see,

493
00:22:57,920 --> 00:22:59,600
Speaker 1: and we run all of our laws of physics, we

494
00:22:59,720 --> 00:23:02,760
Speaker 1: see much wider variation in our simulations than we see

495
00:23:02,800 --> 00:23:05,720
Speaker 1: out there in the actual universe. That tells us like, hmm,

496
00:23:06,160 --> 00:23:08,320
Speaker 1: maybe there's something wrong with this theory. This is something

497
00:23:08,359 --> 00:23:10,760
Speaker 1: that we're putting into our simulations that isn't doing a

498
00:23:10,760 --> 00:23:13,520
Speaker 1: good job of describing what we're actually seeing.

499
00:23:13,880 --> 00:23:15,880
Speaker 5: I think you're saying that the ratio between dark matter

500
00:23:15,920 --> 00:23:20,240
Speaker 5: and regular matter is too constant, like it's too consistent

501
00:23:20,720 --> 00:23:23,200
Speaker 5: across the board of the universe, which means that maybe

502
00:23:23,200 --> 00:23:25,359
Speaker 5: the problem is that what we expect to see in

503
00:23:25,400 --> 00:23:26,720
Speaker 5: the universe is wrong or something.

504
00:23:26,880 --> 00:23:29,600
Speaker 1: Yeah, because for that to happen, you might expect some

505
00:23:29,640 --> 00:23:32,040
Speaker 1: sort of like interaction between them, for them to turn

506
00:23:32,080 --> 00:23:34,440
Speaker 1: back and forth into each other, or interact with each other,

507
00:23:34,680 --> 00:23:37,280
Speaker 1: some process that's keeping them so tightly coupled. But we

508
00:23:37,320 --> 00:23:40,399
Speaker 1: think that dark matter and atomic matter don't interact except

509
00:23:40,400 --> 00:23:43,520
Speaker 1: through gravity, so we don't have a process for making

510
00:23:43,560 --> 00:23:48,080
Speaker 1: this happen. The alternative theory mind actually predicts this perfectly.

511
00:23:48,640 --> 00:23:51,240
Speaker 1: Like Mond says, there is no dark matter, there's just

512
00:23:51,400 --> 00:23:54,959
Speaker 1: normal matter, and gravity changes how things spin, and the

513
00:23:55,000 --> 00:23:59,119
Speaker 1: apparent rotational velocity of these galaxies should be very tightly

514
00:23:59,119 --> 00:24:02,880
Speaker 1: connected to their tightness because the rotation velocity just comes

515
00:24:02,960 --> 00:24:06,360
Speaker 1: from stars. So the mind prediction is like bang on

516
00:24:06,560 --> 00:24:09,520
Speaker 1: exactly what we see, whereas the dark matter prediction is

517
00:24:09,560 --> 00:24:11,760
Speaker 1: sort of like scattered all over the place and doesn't

518
00:24:11,760 --> 00:24:14,280
Speaker 1: do a good job of describing what we see. For

519
00:24:14,320 --> 00:24:17,359
Speaker 1: astronomy nerds out there, this is called the Tully Fisher relation.

520
00:24:18,280 --> 00:24:20,040
Speaker 5: I think you're saying is that maybe this idea of

521
00:24:20,119 --> 00:24:22,920
Speaker 5: mind that maybe our laws of physics are wrong, does

522
00:24:22,960 --> 00:24:26,679
Speaker 5: a better job of explaining the consistency of what we

523
00:24:26,720 --> 00:24:29,480
Speaker 5: see out there in the galaxies, Like, it makes more

524
00:24:29,520 --> 00:24:31,960
Speaker 5: sense it gravity works differently than we think it does,

525
00:24:32,160 --> 00:24:34,359
Speaker 5: and then it would be for there to be a

526
00:24:34,359 --> 00:24:35,440
Speaker 5: bunch of invisible mass.

527
00:24:35,520 --> 00:24:38,240
Speaker 1: Yeah, it does a better job of explaining the relationship

528
00:24:38,240 --> 00:24:41,880
Speaker 1: between galaxy brightness and rotation that we see in the universe.

529
00:24:42,200 --> 00:24:44,720
Speaker 1: We see them much more tightly coupled and connected in

530
00:24:44,760 --> 00:24:47,240
Speaker 1: the universe than we would expect if it was due

531
00:24:47,280 --> 00:24:49,200
Speaker 1: to dark matter. If you've got like a random sampling

532
00:24:49,200 --> 00:24:50,960
Speaker 1: of how much dark matter and how much normal matter,

533
00:24:51,160 --> 00:24:53,199
Speaker 1: you expect there to be more of a spread. But

534
00:24:53,320 --> 00:24:56,040
Speaker 1: moond predicts a very tight relationship because there is no

535
00:24:56,160 --> 00:24:58,680
Speaker 1: dark matter, and so it does a better job of

536
00:24:58,720 --> 00:25:00,800
Speaker 1: predicting what we actually see out there in the universe.

537
00:25:00,880 --> 00:25:03,040
Speaker 1: This is like kind of a headache for dark matter

538
00:25:03,080 --> 00:25:03,639
Speaker 1: as a theory.

539
00:25:04,040 --> 00:25:07,200
Speaker 5: Interesting, like, it has its failings. The idea that it's

540
00:25:07,240 --> 00:25:10,000
Speaker 5: invisible matter, and this idea that maybe the laws of

541
00:25:10,000 --> 00:25:12,120
Speaker 5: physics are wrong comes in and says, hey, I can

542
00:25:12,119 --> 00:25:14,800
Speaker 5: fix that, but maybe it doesn't fix everything, which is

543
00:25:14,840 --> 00:25:16,960
Speaker 5: why it's still not the prevailing theory.

544
00:25:17,119 --> 00:25:19,879
Speaker 1: Yeah, exactly. But it's been like a real thorn in

545
00:25:19,920 --> 00:25:21,720
Speaker 1: the side of dark matter for a long time and

546
00:25:21,800 --> 00:25:23,600
Speaker 1: keeps a lot of people, I think, from accepting this

547
00:25:23,720 --> 00:25:25,400
Speaker 1: idea that dark matter might be real.

548
00:25:25,600 --> 00:25:27,679
Speaker 5: Well, there is a new theory, a new idea that

549
00:25:27,800 --> 00:25:30,520
Speaker 5: maybe would make dark matter make more sense, and that's

550
00:25:30,560 --> 00:25:33,720
Speaker 5: the idea that maybe it's a superfluid. So let's get

551
00:25:33,720 --> 00:25:36,840
Speaker 5: into what a superfluid is and whether dark matter could

552
00:25:36,880 --> 00:25:40,160
Speaker 5: be one of these super powered fluids. But first let's

553
00:25:40,160 --> 00:25:40,920
Speaker 5: take a quick break.

554
00:25:44,920 --> 00:25:47,920
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Speaker 5: All right, we're asking the question could dark matter be

623
00:29:25,120 --> 00:29:27,920
Speaker 5: a super fluid? And we're asking the question because there

624
00:29:27,920 --> 00:29:30,520
Speaker 5: are some things about dark matter that we can't quite

625
00:29:30,520 --> 00:29:32,760
Speaker 5: explain out there even if we assume it's some kind

626
00:29:32,800 --> 00:29:34,920
Speaker 5: of stuff, some kind of particle, some kind of fluid,

627
00:29:35,000 --> 00:29:38,520
Speaker 5: it doesn't quite explain the ratio of regular matter and

628
00:29:38,600 --> 00:29:40,360
Speaker 5: dark matter we see out there in the universe.

629
00:29:40,520 --> 00:29:42,800
Speaker 1: Yeah, that's right, And so people are trying to be creative.

630
00:29:42,800 --> 00:29:45,480
Speaker 1: They're saying, like, dark matter by itself doesn't quite work

631
00:29:45,480 --> 00:29:48,880
Speaker 1: as a theory. Mond by itself has lots more problems

632
00:29:48,920 --> 00:29:51,200
Speaker 1: than dark matter by itself, Like neither of them are perfect.

633
00:29:51,320 --> 00:29:53,680
Speaker 1: Is there some way we could take dark matter and

634
00:29:53,760 --> 00:29:56,760
Speaker 1: make it a little mandier, right, to try to capture

635
00:29:56,800 --> 00:29:59,440
Speaker 1: some of the things that Mond has. Remember, the key

636
00:29:59,480 --> 00:30:02,800
Speaker 1: feature of is that it changes the effect of gravity

637
00:30:03,080 --> 00:30:05,680
Speaker 1: over some distances. So people were like, well, is there

638
00:30:05,680 --> 00:30:08,960
Speaker 1: any way we could change dark matter or tweak dark

639
00:30:09,000 --> 00:30:12,520
Speaker 1: matter so that it basically has the same effect Asmond,

640
00:30:12,680 --> 00:30:15,320
Speaker 1: but only in these scenarios the hearts of galaxies where

641
00:30:15,400 --> 00:30:18,760
Speaker 1: dark matter seems to be having a problem.

642
00:30:17,720 --> 00:30:19,560
Speaker 5: All right, And so the idea is that maybe dark

643
00:30:19,600 --> 00:30:22,800
Speaker 5: matter is a superfluid, which is like a superpowered fluid

644
00:30:22,960 --> 00:30:25,520
Speaker 5: that was I don't know, born in krypton or something

645
00:30:25,680 --> 00:30:27,520
Speaker 5: inherited a power ring from an alien.

646
00:30:27,640 --> 00:30:30,360
Speaker 1: The superfluid is not from cartoons and not just from

647
00:30:30,400 --> 00:30:33,320
Speaker 1: science fiction. It's a real thing. A couple of Nobel

648
00:30:33,360 --> 00:30:36,680
Speaker 1: Prizes have been won already because of superfluids, and they're

649
00:30:36,680 --> 00:30:40,640
Speaker 1: called superfluids. Sort of an analogy to superconductors, right. A

650
00:30:40,680 --> 00:30:44,080
Speaker 1: superconductor is someone that conducts electricity, so you can send

651
00:30:44,320 --> 00:30:47,240
Speaker 1: energy down a wire if it's superconducting and lose none

652
00:30:47,280 --> 00:30:49,480
Speaker 1: of it, right, You don't turn any of it into heat,

653
00:30:49,560 --> 00:30:53,240
Speaker 1: and so superfluid is similar. It's a liquid that flows,

654
00:30:53,600 --> 00:30:56,640
Speaker 1: but without any internal resistance, so the bits just sort

655
00:30:56,640 --> 00:30:59,280
Speaker 1: of slide by each other. It doesn't heat up at

656
00:30:59,320 --> 00:31:01,920
Speaker 1: all as it flows. It doesn't lose energy. Like if

657
00:31:01,920 --> 00:31:03,719
Speaker 1: you take a bucket of water and you put your

658
00:31:03,720 --> 00:31:05,640
Speaker 1: finger in it and spin it, you'll get a little

659
00:31:05,720 --> 00:31:08,840
Speaker 1: vortex that's forming. But eventually that vortex will sort of

660
00:31:08,880 --> 00:31:11,360
Speaker 1: peeter out right, the energy will diffuse and the water

661
00:31:11,400 --> 00:31:14,800
Speaker 1: will stop moving. In a superfluid, that doesn't happen. You

662
00:31:14,880 --> 00:31:17,200
Speaker 1: start a vortex and it just spins forever.

663
00:31:17,480 --> 00:31:19,920
Speaker 5: Wow, it's super interesting. I guess that's the idea of

664
00:31:20,000 --> 00:31:24,160
Speaker 5: zero viscosity, which means no friction between the molecules of

665
00:31:24,200 --> 00:31:26,000
Speaker 5: the fluid. But I guess maybe let's thig in a

666
00:31:26,040 --> 00:31:29,360
Speaker 5: little bit. This might be interesting. What exactly is viscosity

667
00:31:29,440 --> 00:31:31,520
Speaker 5: or what exactly is friction? Like, where does that come from?

668
00:31:31,600 --> 00:31:34,480
Speaker 5: So it comes from the interaction of the bits inside

669
00:31:34,520 --> 00:31:34,800
Speaker 5: of it.

670
00:31:35,200 --> 00:31:37,840
Speaker 1: Right when we talk about like an ideal gas, we're

671
00:31:37,880 --> 00:31:40,960
Speaker 1: talking about particles flying through space, but we ignore the

672
00:31:40,960 --> 00:31:44,080
Speaker 1: possibility that they can bump off each other and exchange energy.

673
00:31:44,240 --> 00:31:46,760
Speaker 1: In real life, the particles inside of gas can bump

674
00:31:46,800 --> 00:31:49,520
Speaker 1: off each other, can exchange energy, and the same thing

675
00:31:49,560 --> 00:31:52,280
Speaker 1: with a liquid. In the case of a zero viscosity

676
00:31:52,320 --> 00:31:55,600
Speaker 1: liquid a superfluid, then the particles don't really bump off

677
00:31:55,600 --> 00:31:58,280
Speaker 1: each other and they can like change places without losing

678
00:31:58,320 --> 00:31:59,480
Speaker 1: any of their energy.

679
00:31:59,600 --> 00:32:01,280
Speaker 5: What do you mean they don't bump into each other.

680
00:32:01,360 --> 00:32:03,880
Speaker 5: They do bump, but they don't lose energy, or they

681
00:32:03,960 --> 00:32:06,280
Speaker 5: don't bump at all, Like the things inside of the

682
00:32:06,320 --> 00:32:08,240
Speaker 5: liquid don't interact with it with it self.

683
00:32:08,360 --> 00:32:10,240
Speaker 1: When you're thinking about a liquid, it's sort of like

684
00:32:10,240 --> 00:32:12,800
Speaker 1: an emergent object, and it's easiest to think about it

685
00:32:12,840 --> 00:32:16,200
Speaker 1: like layers of liquid. Imagine like two layers of a

686
00:32:16,240 --> 00:32:18,880
Speaker 1: liquid passing by each other, and think about whether there's

687
00:32:18,920 --> 00:32:22,160
Speaker 1: like friction between those layers. Say, for example, say for example,

688
00:32:22,160 --> 00:32:25,160
Speaker 1: you have a tube and you're pushing some liquid through it, right,

689
00:32:25,200 --> 00:32:27,400
Speaker 1: And if it's a very viscous liquid, it's going to

690
00:32:27,440 --> 00:32:30,640
Speaker 1: flow more rapidly near the center than near the.

691
00:32:30,560 --> 00:32:34,520
Speaker 5: Walls because I get the fluid particles near the walls

692
00:32:34,520 --> 00:32:37,240
Speaker 5: of the tube are hitting the particles of the tube, right,

693
00:32:37,560 --> 00:32:40,400
Speaker 5: and so they lose energy. They're like bumping against the wall.

694
00:32:40,520 --> 00:32:42,160
Speaker 1: And it's not just that they're bumping against the wall.

695
00:32:42,160 --> 00:32:44,440
Speaker 1: Think about like, as the layers are passing by each other,

696
00:32:44,560 --> 00:32:47,360
Speaker 1: are the particles grabbing at each other? Like what is

697
00:32:47,440 --> 00:32:50,360
Speaker 1: friction anyway? Like if you run your finger along the surface,

698
00:32:50,400 --> 00:32:53,200
Speaker 1: why is kinetic energy getting turned into heat? Because the

699
00:32:53,240 --> 00:32:56,280
Speaker 1: particles in your finger are grabbing at the particles on

700
00:32:56,360 --> 00:33:00,000
Speaker 1: the table, there's little deformities and there's bonds between them

701
00:33:00,080 --> 00:33:02,800
Speaker 1: that are getting broken and reformed. And the same thing

702
00:33:02,840 --> 00:33:05,240
Speaker 1: happens inside a liquid. When you have like layers of

703
00:33:05,360 --> 00:33:08,040
Speaker 1: liquid passing by each other, they have an interaction that

704
00:33:08,160 --> 00:33:10,360
Speaker 1: they can grab at each other and sort of like

705
00:33:10,440 --> 00:33:13,520
Speaker 1: slow the next layer down. And it's super fluid. That

706
00:33:13,560 --> 00:33:15,680
Speaker 1: doesn't happen and the layers can sort of like pass

707
00:33:15,720 --> 00:33:17,760
Speaker 1: by each other without any friction at all.

708
00:33:18,680 --> 00:33:19,880
Speaker 5: And why isn't it I guess it.

709
00:33:19,840 --> 00:33:22,080
Speaker 1: Just depends on the interaction between the particles.

710
00:33:22,160 --> 00:33:22,320
Speaker 6: Right.

711
00:33:22,360 --> 00:33:23,920
Speaker 1: It's not something you can do with a normal liquid

712
00:33:23,960 --> 00:33:26,320
Speaker 1: very easily. It's a quantum property. Right, It's not something

713
00:33:26,360 --> 00:33:29,200
Speaker 1: you can really understand in an intuitive level just thinking

714
00:33:29,200 --> 00:33:31,440
Speaker 1: about little balls. Instead, you need to think about these

715
00:33:31,480 --> 00:33:34,040
Speaker 1: objects as quantum objects, which means you to think about

716
00:33:34,040 --> 00:33:37,440
Speaker 1: their wave functions. And when these things get really really cold,

717
00:33:37,680 --> 00:33:40,720
Speaker 1: then you have very little uncertainty on their temperature that

718
00:33:40,760 --> 00:33:44,680
Speaker 1: their wave functions grow really really wide, because the Heisenbergen

719
00:33:44,680 --> 00:33:47,480
Speaker 1: certainty principle tells you can't know something's momentum and it's

720
00:33:47,520 --> 00:33:50,440
Speaker 1: location very very well. So when you cool something down,

721
00:33:50,480 --> 00:33:53,640
Speaker 1: it's wave function grows very very large. So now instead

722
00:33:53,680 --> 00:33:55,760
Speaker 1: of having just like a bunch of little particles bouncing

723
00:33:55,800 --> 00:33:57,600
Speaker 1: around that you can sort of think of as particles,

724
00:33:57,680 --> 00:34:00,880
Speaker 1: you have these overlapping wave functions which beween these objects,

725
00:34:01,040 --> 00:34:03,600
Speaker 1: and they form like one big quantum state, and they

726
00:34:03,600 --> 00:34:06,560
Speaker 1: tend to move like all together instead of interacting with

727
00:34:06,640 --> 00:34:09,439
Speaker 1: each other, so they're like more tightly coupled to each

728
00:34:09,440 --> 00:34:12,360
Speaker 1: other weirdly, which gives this superfluid state.

729
00:34:12,960 --> 00:34:14,919
Speaker 5: I see, I guess you're saying. I think the cold

730
00:34:15,000 --> 00:34:17,360
Speaker 5: or something gets the bigger, the wave function of the

731
00:34:17,400 --> 00:34:20,760
Speaker 5: particles gets, which means that their things get fuzzier almost

732
00:34:20,800 --> 00:34:22,919
Speaker 5: in a way, right Like instead of a little tiny ball,

733
00:34:22,960 --> 00:34:26,680
Speaker 5: suddenly it's more like a hazy blob. And it's kind

734
00:34:26,680 --> 00:34:29,040
Speaker 5: of hard maybe for two hazy blobs to really drag

735
00:34:29,080 --> 00:34:30,600
Speaker 5: on each other. Is that kind of what you're saying.

736
00:34:30,719 --> 00:34:33,720
Speaker 1: Yeah, And it acts more coherently. Instead of individual particles

737
00:34:33,719 --> 00:34:35,759
Speaker 1: which you can grab at each other, now it's like

738
00:34:35,800 --> 00:34:38,440
Speaker 1: a huge train of particles that tend to move together

739
00:34:38,960 --> 00:34:41,520
Speaker 1: rather than bumping against each other. So it's like it's

740
00:34:41,520 --> 00:34:44,359
Speaker 1: all much more coordinated. Now it's like a random crowd

741
00:34:44,360 --> 00:34:46,840
Speaker 1: of people bumping into each other. Now it's like a

742
00:34:46,920 --> 00:34:49,880
Speaker 1: tightly packed formation of a marching band walking down the street,

743
00:34:49,920 --> 00:34:51,399
Speaker 1: where they don't bump into each other at all. They

744
00:34:51,440 --> 00:34:52,400
Speaker 1: just like flow.

745
00:34:52,640 --> 00:34:54,600
Speaker 5: And so this happens. For example, here on Earth, if

746
00:34:54,600 --> 00:34:58,080
Speaker 5: you cool helium a lot, you get a Bose Einstein concept,

747
00:34:58,120 --> 00:34:59,239
Speaker 5: which is superfluid.

748
00:34:59,360 --> 00:35:02,480
Speaker 1: The first time is trition of this was in superfluid helium.

749
00:35:02,760 --> 00:35:05,360
Speaker 1: We get the nineteen ninety six Nobel Prize and Physics

750
00:35:05,400 --> 00:35:08,120
Speaker 1: at Stanford for that that wasn't actually a Bose einsigin

751
00:35:08,200 --> 00:35:10,879
Speaker 1: contins eate, but it is a superfluid. It can flow

752
00:35:10,960 --> 00:35:14,480
Speaker 1: without losing any energy. Another example of a superfluid is

753
00:35:14,480 --> 00:35:17,839
Speaker 1: a Bose Einstein contensate. Another special state of matter rape

754
00:35:17,840 --> 00:35:21,000
Speaker 1: a whole podcast about that again, where you're cooling atoms

755
00:35:21,080 --> 00:35:23,480
Speaker 1: down in a trap to make them very very cold

756
00:35:23,480 --> 00:35:26,520
Speaker 1: and overlapping, so they have other weird quantum properties as well,

757
00:35:26,600 --> 00:35:29,920
Speaker 1: which include being a superfluid. We also think we have

758
00:35:30,000 --> 00:35:34,600
Speaker 1: seen superfluid sort of indirectly inside the Large Hadron collider.

759
00:35:34,920 --> 00:35:37,920
Speaker 1: When we smash big atoms together, like lead nuclei and

760
00:35:37,960 --> 00:35:41,000
Speaker 1: gold nuclei, we can make this state of matter called

761
00:35:41,040 --> 00:35:43,839
Speaker 1: a quark gluon plasma. And one of the features of it,

762
00:35:43,880 --> 00:35:46,280
Speaker 1: we think is that there's a little bit of superfluidity,

763
00:35:46,400 --> 00:35:49,000
Speaker 1: very very briefly at the heart of that thing while

764
00:35:49,000 --> 00:35:49,640
Speaker 1: it exists.

765
00:35:49,800 --> 00:35:51,759
Speaker 5: I mean, when you smash particles together, you get so

766
00:35:51,880 --> 00:35:55,960
Speaker 5: much density of energy and these particles really packed together

767
00:35:56,040 --> 00:35:58,759
Speaker 5: that they behave like a superfluid for a tiny little bit.

768
00:35:58,920 --> 00:36:00,719
Speaker 1: Yeah, for a tiny little bit. Even though it's super

769
00:36:00,760 --> 00:36:04,280
Speaker 1: duper hot, it's also so dense that these particles undergo

770
00:36:04,320 --> 00:36:07,240
Speaker 1: this new phase change into a quark glow on plasma,

771
00:36:07,280 --> 00:36:10,040
Speaker 1: which can also be a superfluid. So a superfluid isn't

772
00:36:10,040 --> 00:36:12,280
Speaker 1: like one unique state of matter. It's like a description

773
00:36:12,360 --> 00:36:14,480
Speaker 1: of a phase of matter, the way like some phases

774
00:36:14,480 --> 00:36:18,000
Speaker 1: of matter conduct electricity and some don't. Some phases of

775
00:36:18,000 --> 00:36:21,239
Speaker 1: matter are fluid and some are superfluid and others aren't.

776
00:36:21,280 --> 00:36:23,719
Speaker 1: So these are just examples of places where we have

777
00:36:23,920 --> 00:36:27,600
Speaker 1: seen superfluidity happen, like really is a thing in the universe.

778
00:36:27,760 --> 00:36:30,240
Speaker 1: We're sure about that, that's not a hypothetical thing.

779
00:36:30,640 --> 00:36:33,080
Speaker 5: And we think it might even be what's happening inside

780
00:36:33,080 --> 00:36:34,319
Speaker 5: of neutron stars, right.

781
00:36:34,280 --> 00:36:36,360
Speaker 1: Yeah, the inside of neutron stars is a lot like

782
00:36:36,360 --> 00:36:39,279
Speaker 1: a quark glow on plasma. It's very very dense, and

783
00:36:39,320 --> 00:36:42,080
Speaker 1: the particles get squeezed together and their wave functions start

784
00:36:42,120 --> 00:36:44,960
Speaker 1: to overlap. And we don't really know what happens inside

785
00:36:44,960 --> 00:36:47,640
Speaker 1: a neutron star because it's some state of matter that

786
00:36:47,680 --> 00:36:51,000
Speaker 1: we can't really access anywhere else, and all the forces

787
00:36:51,000 --> 00:36:54,160
Speaker 1: come into play, including gravity and the strong force, and

788
00:36:54,200 --> 00:36:57,160
Speaker 1: it really tests our ability to even do calculations or

789
00:36:57,160 --> 00:36:59,360
Speaker 1: predictab what might happen. We think that weird states of

790
00:36:59,400 --> 00:37:02,719
Speaker 1: matter like new Glear pasta might occur, and there might

791
00:37:02,760 --> 00:37:05,759
Speaker 1: also be super fluid states inside the heart of a

792
00:37:05,760 --> 00:37:06,479
Speaker 1: neutron star.

793
00:37:06,600 --> 00:37:10,200
Speaker 5: But is there generally like a recipe for making superfluids? Like,

794
00:37:10,280 --> 00:37:12,759
Speaker 5: what's the thing that makes all of these different examples?

795
00:37:12,840 --> 00:37:13,960
Speaker 5: What do they have in common?

796
00:37:14,040 --> 00:37:17,239
Speaker 1: They all have in common high density. So you squeeze

797
00:37:17,239 --> 00:37:20,960
Speaker 1: these particles together basically so that their wave functions are overlapping,

798
00:37:21,160 --> 00:37:23,759
Speaker 1: and that's how you achieve it. It's easier to do that

799
00:37:23,920 --> 00:37:26,480
Speaker 1: if they're very very low temperature because their wave functions

800
00:37:26,480 --> 00:37:28,840
Speaker 1: are larger. But if you get high enough density, you

801
00:37:28,880 --> 00:37:31,600
Speaker 1: can also achieve it even at high temperatures, like the

802
00:37:31,600 --> 00:37:35,000
Speaker 1: inside of a neutron star. But the crucial thing is density.

803
00:37:35,200 --> 00:37:38,200
Speaker 5: Wonderf It's like, you know, taking a bunch of water balloons.

804
00:37:38,560 --> 00:37:41,200
Speaker 5: When you squeeze them together, they almost become superfluid.

805
00:37:42,280 --> 00:37:43,960
Speaker 1: Have you been to a birthday party recently where he

806
00:37:44,000 --> 00:37:44,760
Speaker 1: sawways happen?

807
00:37:45,280 --> 00:37:47,560
Speaker 5: Well, Like, if you have a bunch of water balloons

808
00:37:47,640 --> 00:37:50,239
Speaker 5: out and they're really far spread, far apart, they sort

809
00:37:50,239 --> 00:37:52,960
Speaker 5: of behave like maybe like little particles, but if you

810
00:37:53,000 --> 00:37:54,960
Speaker 5: sort of pack them together in a bucket, they kind

811
00:37:54,960 --> 00:37:56,000
Speaker 5: of act like a fluid.

812
00:37:56,080 --> 00:37:58,879
Speaker 1: Right, Yeah, that's true. I never thought about what it's

813
00:37:59,000 --> 00:38:01,600
Speaker 1: like for a bunch of water balloons to slide out

814
00:38:01,600 --> 00:38:03,600
Speaker 1: of a bucket. Have you like dumped a bucket of

815
00:38:03,600 --> 00:38:05,120
Speaker 1: water balloons on somebody's head before?

816
00:38:05,360 --> 00:38:07,960
Speaker 5: Yeah, yeah, super fluid water balloons.

817
00:38:08,000 --> 00:38:10,719
Speaker 1: Actually that sounds like super fun. But you're exactly right.

818
00:38:10,760 --> 00:38:14,160
Speaker 1: When simple things come together, they can do new, weird things.

819
00:38:14,200 --> 00:38:17,239
Speaker 1: And that's the whole amazing size of chemistry.

820
00:38:17,280 --> 00:38:17,440
Speaker 6: Right.

821
00:38:17,440 --> 00:38:19,960
Speaker 1: We have these phases of matter that come out of

822
00:38:19,960 --> 00:38:22,160
Speaker 1: the way these particles interact with each other or don't

823
00:38:22,160 --> 00:38:26,080
Speaker 1: interact with each other, and generate these emergent properties electrical

824
00:38:26,120 --> 00:38:29,880
Speaker 1: conductivity or shininess, or liquid phases or other weird phases

825
00:38:29,920 --> 00:38:32,440
Speaker 1: of matter. It's incredible what matter in the universe can do.

826
00:38:32,719 --> 00:38:35,200
Speaker 1: The variety of things that come out just of the

827
00:38:35,200 --> 00:38:38,080
Speaker 1: basic laws from the interactions at the microphysical level. It

828
00:38:38,080 --> 00:38:38,920
Speaker 1: always amazes me.

829
00:38:39,520 --> 00:38:42,080
Speaker 5: Okay, so that's what a superfluid is. And now the

830
00:38:42,120 --> 00:38:45,520
Speaker 5: idea is that maybe dark matter could be a super fluid.

831
00:38:45,600 --> 00:38:47,759
Speaker 5: So it's the idea that dark matter is made out

832
00:38:47,760 --> 00:38:50,160
Speaker 5: of little particles and then when you somehow get them

833
00:38:50,200 --> 00:38:52,360
Speaker 5: really close to each other, they behave like a superfluid.

834
00:38:52,520 --> 00:38:55,560
Speaker 1: Yeah, the idea is that dark matter is still dark matter.

835
00:38:55,560 --> 00:38:59,879
Speaker 1: It's still some particle that's invisible and intangible and does

836
00:39:00,080 --> 00:39:03,040
Speaker 1: interact with us except through gravity. But if you get

837
00:39:03,160 --> 00:39:07,799
Speaker 1: enough dark matter together under the densest conditions, maybe it's

838
00:39:07,880 --> 00:39:11,759
Speaker 1: forming a superfluid. And now it give it new properties

839
00:39:12,000 --> 00:39:14,480
Speaker 1: like those water balloons in the bucket. It can do

840
00:39:14,640 --> 00:39:16,960
Speaker 1: things when it's all together in those conditions that it

841
00:39:16,960 --> 00:39:19,879
Speaker 1: couldn't do otherwise. And the idea is that this new

842
00:39:19,960 --> 00:39:24,160
Speaker 1: superfluid state of dark matter might explain what's happening inside

843
00:39:24,280 --> 00:39:28,040
Speaker 1: galaxies that currently dark matter as a theory can't explain.

844
00:39:28,719 --> 00:39:31,920
Speaker 5: Interesting But I thought, maybe dark matter didn't interact with itself.

845
00:39:32,080 --> 00:39:34,879
Speaker 5: So isn't it already a superfluid that doesn't have any

846
00:39:34,920 --> 00:39:35,680
Speaker 5: internal friction.

847
00:39:35,920 --> 00:39:38,000
Speaker 1: Yeah, so currently we think that dark matter doesn't have

848
00:39:38,000 --> 00:39:40,799
Speaker 1: any interactions. So you might think, oh, yeah, dark matter

849
00:39:40,840 --> 00:39:43,000
Speaker 1: out there in space is a collisionless fluid. Isn't that

850
00:39:43,040 --> 00:39:45,920
Speaker 1: also a superfluid? Right? Not technically, because they don't have

851
00:39:46,000 --> 00:39:49,000
Speaker 1: overlapping wave functions. Like if you just have a really

852
00:39:49,080 --> 00:39:52,200
Speaker 1: dilute gas of dark matter, like we think exists out

853
00:39:52,200 --> 00:39:54,759
Speaker 1: there at the edge of the galaxy and beyond, that's

854
00:39:54,800 --> 00:39:57,000
Speaker 1: not really a superfluid because the particles are just really

855
00:39:57,040 --> 00:39:59,200
Speaker 1: far away from each other. To have a superfluid have

856
00:39:59,280 --> 00:40:02,120
Speaker 1: these new funnel emerge, you really have to have them

857
00:40:02,160 --> 00:40:04,880
Speaker 1: close enough to each other, so the wave functions overlap.

858
00:40:05,400 --> 00:40:08,480
Speaker 5: So it's more about the quantum overlap of the individual

859
00:40:08,480 --> 00:40:12,480
Speaker 5: particles and less about the kind of frictionless flow of

860
00:40:12,520 --> 00:40:12,960
Speaker 5: the fluid.

861
00:40:13,600 --> 00:40:16,040
Speaker 1: For dark matter, Yeah, and in this case, it's the

862
00:40:16,160 --> 00:40:20,360
Speaker 1: overlap of those particles that generates new phenomena like frictionless flow.

863
00:40:20,680 --> 00:40:23,239
Speaker 1: And in the case of dark matter superfluid, they think

864
00:40:23,320 --> 00:40:27,319
Speaker 1: it can effectively create a new force. What emerges from

865
00:40:27,360 --> 00:40:29,680
Speaker 1: a dark matter superfluid is sort of like a new

866
00:40:29,719 --> 00:40:33,440
Speaker 1: force which effectively can change the way that gravity works,

867
00:40:33,760 --> 00:40:36,400
Speaker 1: giving you exactly the same behavior that we see in

868
00:40:36,440 --> 00:40:38,400
Speaker 1: the mind theory of dark matter.

869
00:40:38,560 --> 00:40:40,840
Speaker 5: To me, the question should be is dark matter a

870
00:40:41,000 --> 00:40:43,560
Speaker 5: super duper fluid? All right? Well, let's get into how

871
00:40:43,680 --> 00:40:46,319
Speaker 5: dark matter being a super duper fluid at the heart

872
00:40:46,320 --> 00:40:48,720
Speaker 5: of galaxies could explain some of the things we can't

873
00:40:48,840 --> 00:40:52,479
Speaker 5: understand or explain about the current model of dark matter.

874
00:40:53,080 --> 00:40:54,879
Speaker 5: But first, let's take another quick break.

875
00:40:59,000 --> 00:41:00,799
Speaker 1: When you pop a piece of cheese into your mouth,

876
00:41:00,920 --> 00:41:04,040
Speaker 1: or enjoy a rich spoonful of Greek yogurt. You're probably

877
00:41:04,120 --> 00:41:08,160
Speaker 1: not thinking about the environmental impact of each and every bite,

878
00:41:08,200 --> 00:41:10,800
Speaker 1: but the people in the dairy industry are. US Dairy

879
00:41:10,840 --> 00:41:15,120
Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse

880
00:41:15,160 --> 00:41:17,759
Speaker 1: gas neutral by twenty to fifty That's why they're working

881
00:41:17,760 --> 00:41:20,080
Speaker 1: hard every day to find new ways to reduce waste,

882
00:41:20,160 --> 00:41:24,399
Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. Take water,

883
00:41:24,440 --> 00:41:27,520
Speaker 1: for example, most dairy farms reuse water up to four

884
00:41:27,600 --> 00:41:31,040
Speaker 1: times the same water cools the milk, cleans equipment, washes

885
00:41:31,080 --> 00:41:33,880
Speaker 1: the barn, and irrigates the crops. How is US Dairy

886
00:41:33,920 --> 00:41:37,680
Speaker 1: tackling greenhouse gases. Many farms use anaerobic digestors that turn

887
00:41:37,719 --> 00:41:41,640
Speaker 1: the methane from maneuver into renewable energy that can power farms, towns,

888
00:41:41,640 --> 00:41:43,719
Speaker 1: and electric cars. So the next time you grab a

889
00:41:43,760 --> 00:41:45,759
Speaker 1: slice of pizza or lick an ice cream cone, know

890
00:41:45,840 --> 00:41:48,520
Speaker 1: that dairy farmers and processors around the country are using

891
00:41:48,560 --> 00:41:52,040
Speaker 1: the latest practices and innovations to provide the nutrient dense

892
00:41:52,160 --> 00:41:54,879
Speaker 1: dairy products we love with less of an impact. Visit

893
00:41:55,000 --> 00:41:57,759
Speaker 1: US dairy dot com slash sustainability to learn more.

894
00:41:58,440 --> 00:42:02,000
Speaker 3: Hi, I'm David Eagleman from the podcast Inner Cosmos, which

895
00:42:02,040 --> 00:42:05,399
Speaker 3: recently hit the number one science podcast in America. I'm

896
00:42:05,400 --> 00:42:09,160
Speaker 3: a neuroscientists at Stanford, and I've spent my career exploring

897
00:42:09,239 --> 00:42:10,920
Speaker 3: the three pound universe.

898
00:42:10,640 --> 00:42:11,400
Speaker 1: In our heads.

899
00:42:11,719 --> 00:42:14,120
Speaker 3: We're looking at a whole new series of episodes this

900
00:42:14,200 --> 00:42:18,040
Speaker 3: season to understand why and how our lives look the

901
00:42:18,040 --> 00:42:21,239
Speaker 3: way they do. Why does your memory drift so much?

902
00:42:21,840 --> 00:42:25,080
Speaker 3: Why is it so hard to keep a secret, When

903
00:42:25,120 --> 00:42:28,960
Speaker 3: should you not trust your intuition? Why do brains so

904
00:42:29,200 --> 00:42:32,040
Speaker 3: easily fall for magic tricks? And why do they love

905
00:42:32,160 --> 00:42:37,240
Speaker 3: conspiracy theories. I'm hitting these questions and hundreds more because

906
00:42:37,280 --> 00:42:39,960
Speaker 3: the more we know about what's running under the hood,

907
00:42:40,400 --> 00:42:43,920
Speaker 3: the better we can steer our lives. Join me weekly

908
00:42:44,080 --> 00:42:47,360
Speaker 3: to explore the relationship between your brain and your life

909
00:42:47,719 --> 00:42:52,160
Speaker 3: by digging into unexpected questions. Listen to Inner Cosmos with

910
00:42:52,200 --> 00:42:55,840
Speaker 3: David Eagleman on the iHeartRadio app, Apple Podcasts, or wherever

911
00:42:55,920 --> 00:42:57,120
Speaker 3: you get your podcasts.

912
00:42:58,960 --> 00:43:02,200
Speaker 4: Parents, are you for a screen free, engaging way to

913
00:43:02,239 --> 00:43:04,799
Speaker 4: teach your kids the Bible, one that's easy to understand

914
00:43:05,000 --> 00:43:08,799
Speaker 4: and enjoyable for multiple ages. Kids, Bible Stories podcast is

915
00:43:08,840 --> 00:43:11,640
Speaker 4: here to help. I created this for my own children,

916
00:43:11,719 --> 00:43:15,000
Speaker 4: and it's now a favorite among thousands of families. Kids

917
00:43:15,160 --> 00:43:18,560
Speaker 4: love the vivid imagery, scriptures, and sound effects, while parents

918
00:43:18,560 --> 00:43:22,400
Speaker 4: appreciate the apply section for meaningful conversations. We have hundreds

919
00:43:22,400 --> 00:43:25,640
Speaker 4: and hundreds of beautiful episodes that bring the Bible to

920
00:43:25,719 --> 00:43:29,360
Speaker 4: life when you simply press play. It's a sound and

921
00:43:29,480 --> 00:43:33,160
Speaker 4: practical resource that walks alongside you as you teach your kids.

922
00:43:33,760 --> 00:43:36,759
Speaker 4: We want kids to see how incredible God's word is

923
00:43:36,960 --> 00:43:41,280
Speaker 4: in an engaging and memorable way with Kids' Bible Stories podcast.

924
00:43:42,520 --> 00:43:45,319
Speaker 4: Listen to Kids' Bible Stories Podcast on the iHeartRadio app,

925
00:43:45,400 --> 00:43:48,279
Speaker 4: Apple Podcasts, or wherever you get your podcasts.

926
00:43:50,760 --> 00:43:53,120
Speaker 13: We think of Franklin as the doddling dude flying a

927
00:43:53,200 --> 00:43:55,360
Speaker 13: kite and no rain, but those experiments are the most

928
00:43:55,560 --> 00:43:59,080
Speaker 13: important scientific discoveries of the time.

929
00:43:59,360 --> 00:43:59,920
Speaker 1: I'm having right.

930
00:44:00,600 --> 00:44:03,799
Speaker 14: Last season, we tackled the ingenuity of Elon Musk with

931
00:44:03,880 --> 00:44:07,200
Speaker 14: biographer Walter Isaacson. This time we're diving into the story

932
00:44:07,200 --> 00:44:10,600
Speaker 14: of Benjamin Franklin, another genius who's desperate to be dusted

933
00:44:10,640 --> 00:44:11,360
Speaker 14: off from history.

934
00:44:11,760 --> 00:44:15,800
Speaker 13: His media empire makes him the most successful self made

935
00:44:15,880 --> 00:44:18,960
Speaker 13: business person in America. I mean, he was never early

936
00:44:19,040 --> 00:44:23,799
Speaker 13: to bed, an early to rise type person. He's enormously famous.

937
00:44:23,840 --> 00:44:26,719
Speaker 13: Women shut wearing their hair and what was called the

938
00:44:26,800 --> 00:44:29,200
Speaker 13: coiffor a La Franklin.

939
00:44:29,200 --> 00:44:31,160
Speaker 1: And who's more relevant now than ever.

940
00:44:31,560 --> 00:44:35,000
Speaker 13: The only other person who could have possibly been the

941
00:44:35,040 --> 00:44:38,359
Speaker 13: first president would have been Benjamin Franklin, but he's too

942
00:44:38,400 --> 00:44:40,759
Speaker 13: old and once Washington to do it.

943
00:44:40,960 --> 00:44:43,319
Speaker 14: Listen to On Benjamin Franklin with Walter Isaacson on the

944
00:44:43,360 --> 00:44:46,640
Speaker 14: iHeartRadio app, Apple Podcasts or wherever you get your podcasts.

945
00:44:56,480 --> 00:44:58,880
Speaker 5: All right, we're asking the question, could bark matter be

946
00:44:58,960 --> 00:45:01,359
Speaker 5: a super fluid? And we're asking the question because there

947
00:45:01,360 --> 00:45:04,719
Speaker 5: are things about dark matter that we can't quite explain.

948
00:45:05,200 --> 00:45:07,080
Speaker 5: I mean, we don't know what it is or what

949
00:45:07,160 --> 00:45:09,399
Speaker 5: it could be, but even our idea of it as

950
00:45:09,440 --> 00:45:11,759
Speaker 5: a particle, as a bit of matter, as bits of matter,

951
00:45:11,840 --> 00:45:13,880
Speaker 5: doesn't quite explain some of the things we see out

952
00:45:13,880 --> 00:45:15,520
Speaker 5: there in the universe. And so the idea is that

953
00:45:15,640 --> 00:45:18,920
Speaker 5: maybe dark matter is a superfluid which might explain these things.

954
00:45:19,000 --> 00:45:20,960
Speaker 1: Yeah, and I think the kernel of the idea what

955
00:45:21,080 --> 00:45:24,160
Speaker 1: generated it is noticing that dark matter as a theory

956
00:45:24,640 --> 00:45:28,560
Speaker 1: seems to have trouble in the densest situations. It works

957
00:45:28,600 --> 00:45:32,359
Speaker 1: really well between galaxy clusters, it works out there in

958
00:45:32,400 --> 00:45:36,080
Speaker 1: space for gravitational lensing of lots of galaxies. It works

959
00:45:36,120 --> 00:45:39,239
Speaker 1: in the early universe, but inside galaxy is currently the

960
00:45:39,320 --> 00:45:42,400
Speaker 1: densest places in the universe is where it struggles. So

961
00:45:42,440 --> 00:45:45,719
Speaker 1: people thought, well, maybe when dark matter gets denser, it

962
00:45:45,760 --> 00:45:48,480
Speaker 1: forms this new state, this superfluid, and then we can

963
00:45:48,480 --> 00:45:51,359
Speaker 1: figure out how to give this superfluid new properties. Maybe

964
00:45:51,360 --> 00:45:54,120
Speaker 1: you can solve the problems of dark matter inside galaxies

965
00:45:54,360 --> 00:45:56,879
Speaker 1: without breaking what dark matter is already so good at

966
00:45:56,880 --> 00:45:59,719
Speaker 1: explaining everywhere else. Right, So the idea is that it

967
00:45:59,760 --> 00:46:03,239
Speaker 1: owns only forms of superfluid inside the dense environment of

968
00:46:03,280 --> 00:46:06,000
Speaker 1: a galaxy. Everywhere else, it's just this normal, boring, old

969
00:46:06,120 --> 00:46:06,840
Speaker 1: dark matter.

970
00:46:06,800 --> 00:46:10,480
Speaker 5: Normal boring but still quite a mysterious and elusive. So

971
00:46:10,520 --> 00:46:13,120
Speaker 5: you're saying that at the center of galaxies, where things

972
00:46:13,160 --> 00:46:16,239
Speaker 5: are pretty dense anyways, right, there are sometimes black holes

973
00:46:16,280 --> 00:46:17,880
Speaker 5: in the middle of galaxies. There are a lot of

974
00:46:18,120 --> 00:46:20,880
Speaker 5: stars clustered together. The ideas that maybe dark matter is

975
00:46:21,239 --> 00:46:24,239
Speaker 5: super duper compact at the center of galaxies more so

976
00:46:24,320 --> 00:46:26,719
Speaker 5: than like at the edges of galaxies, and.

977
00:46:26,640 --> 00:46:29,239
Speaker 1: Not just at the center, but yes, definitely denser at

978
00:46:29,280 --> 00:46:32,239
Speaker 1: the center. But essentially we're thinking about galaxies as like

979
00:46:32,280 --> 00:46:34,359
Speaker 1: a dense place in the universe. And as we talked

980
00:46:34,400 --> 00:46:37,000
Speaker 1: about earlier, how do you make a superfluid. You need

981
00:46:37,000 --> 00:46:39,600
Speaker 1: to get the particles close enough so their wave functions

982
00:46:39,640 --> 00:46:42,960
Speaker 1: overlapped to make the superfluid thing happen. And so that

983
00:46:43,000 --> 00:46:45,040
Speaker 1: can happen in a galaxy because there's a lot of

984
00:46:45,080 --> 00:46:48,560
Speaker 1: gravity there, gathers together a lot of dark matter. Another

985
00:46:48,600 --> 00:46:51,279
Speaker 1: trick they pull is to make dark matter very very

986
00:46:51,560 --> 00:46:55,120
Speaker 1: very very low mass. We know like how much mass

987
00:46:55,320 --> 00:46:57,400
Speaker 1: of dark matter we need, but we don't know how

988
00:46:57,520 --> 00:47:01,040
Speaker 1: much mass each particle has. You make dark matter out

989
00:47:01,080 --> 00:47:04,319
Speaker 1: of really massive particles, you have fewer of them. If

990
00:47:04,320 --> 00:47:07,000
Speaker 1: you make dark matter out of really low mass particles,

991
00:47:07,160 --> 00:47:09,040
Speaker 1: you need more of them. So the folks who are

992
00:47:09,080 --> 00:47:11,239
Speaker 1: working on this theory say that dark matter is really

993
00:47:11,239 --> 00:47:14,560
Speaker 1: really low mass, then there's a huge number of them, right,

994
00:47:14,640 --> 00:47:18,120
Speaker 1: And so they're imagining the centers of galaxies being sworn

995
00:47:18,320 --> 00:47:21,799
Speaker 1: with zillions and zillions of very very low mass dark

996
00:47:21,840 --> 00:47:25,239
Speaker 1: matter particles that come together into a superfluid. And when

997
00:47:25,239 --> 00:47:27,920
Speaker 1: they do that, they get all sorts of new weird behaviors.

998
00:47:28,360 --> 00:47:29,960
Speaker 5: Well, well, let's get into a little bit of what

999
00:47:29,960 --> 00:47:32,040
Speaker 5: those behaviors are like, what do you think happens when

1000
00:47:32,120 --> 00:47:35,560
Speaker 5: dark matter is that close together that the wave functions overlap.

1001
00:47:35,600 --> 00:47:37,920
Speaker 1: So it's really hard to do these calculations because you're

1002
00:47:37,960 --> 00:47:41,160
Speaker 1: talking about like overlapping wave functions of lots and lots

1003
00:47:41,200 --> 00:47:43,400
Speaker 1: and lots and lots of particles. So when physicists need

1004
00:47:43,480 --> 00:47:45,440
Speaker 1: to do that, they try to describe these new behaviors

1005
00:47:45,480 --> 00:47:47,680
Speaker 1: in terms of something they're already familiar with. So the

1006
00:47:47,719 --> 00:47:50,480
Speaker 1: way they usually talk about it is in terms of

1007
00:47:50,640 --> 00:47:54,760
Speaker 1: sound waves propagating through this super fluid. I think about

1008
00:47:54,800 --> 00:47:58,080
Speaker 1: like shock waves moving through it. How if you pull

1009
00:47:58,120 --> 00:47:59,879
Speaker 1: on one part of it that would affect the other

1010
00:48:00,080 --> 00:48:02,239
Speaker 1: parts of it. Dark matter is this super fluid, so

1011
00:48:02,280 --> 00:48:04,919
Speaker 1: it's like weirdly tightly coupled. It acts like a big

1012
00:48:04,960 --> 00:48:08,480
Speaker 1: coherent blob instead of individual pieces. And so they talk

1013
00:48:08,480 --> 00:48:11,799
Speaker 1: about phonons, which are like sound waves moving through this superfluid,

1014
00:48:11,960 --> 00:48:14,839
Speaker 1: and they build up this whole theory which comes out

1015
00:48:14,880 --> 00:48:17,480
Speaker 1: looking like a new force sort of like this dark

1016
00:48:17,480 --> 00:48:19,719
Speaker 1: matter when it enters this superfluid, has a new way

1017
00:48:19,760 --> 00:48:22,480
Speaker 1: to interact with itself that it didn't have before.

1018
00:48:22,719 --> 00:48:24,920
Speaker 5: Well, I guess maybe one thing that's confusing me is

1019
00:48:24,960 --> 00:48:27,560
Speaker 5: that I thought dark matter didn't interact with itself, right,

1020
00:48:27,560 --> 00:48:30,640
Speaker 5: Like the particles of dark matter don't usually or can't

1021
00:48:30,760 --> 00:48:34,720
Speaker 5: bump into themselves. That part of the idea of dark matter.

1022
00:48:34,880 --> 00:48:37,719
Speaker 5: So why would bring them together, really close together make

1023
00:48:37,760 --> 00:48:40,440
Speaker 5: them interact in a different way. If they can't interact

1024
00:48:40,480 --> 00:48:41,640
Speaker 5: with each other, You're.

1025
00:48:41,560 --> 00:48:43,600
Speaker 1: Right, at a particle level, they don't have that kind

1026
00:48:43,640 --> 00:48:46,480
Speaker 1: of interaction. We're only talking about gravity, but now we're

1027
00:48:46,480 --> 00:48:49,759
Speaker 1: adding other weird quantum effects, and quantum effects when they

1028
00:48:49,760 --> 00:48:52,400
Speaker 1: all work together, can make it feel like there's a force.

1029
00:48:52,480 --> 00:48:55,520
Speaker 1: Another example is the poly exclusion principle. That's someone that

1030
00:48:55,560 --> 00:48:57,960
Speaker 1: tells you that, like two fermions can't be in the

1031
00:48:58,000 --> 00:49:00,880
Speaker 1: same location. That's the thing that keep some kinds of

1032
00:49:00,920 --> 00:49:04,600
Speaker 1: stars from collapsing. It allows it to resist the force

1033
00:49:04,680 --> 00:49:07,160
Speaker 1: of gravity that's trying to push it in. It's not

1034
00:49:07,280 --> 00:49:10,239
Speaker 1: technically a force at the particle level, there's no force there,

1035
00:49:10,600 --> 00:49:14,279
Speaker 1: but this quantum behavior of the objects basically acts as

1036
00:49:14,320 --> 00:49:17,520
Speaker 1: a block to gravity. So in the same way, this

1037
00:49:17,600 --> 00:49:20,960
Speaker 1: weird quantum behavior of dark matter when it's a superfluid

1038
00:49:21,120 --> 00:49:24,319
Speaker 1: acts sort of in a way to change gravity. It's

1039
00:49:24,320 --> 00:49:26,520
Speaker 1: sort of like there's a new force it's not an

1040
00:49:26,560 --> 00:49:29,560
Speaker 1: individual new force on the particles. It's a way to

1041
00:49:29,680 --> 00:49:32,799
Speaker 1: describe what happens to all these particles when they do

1042
00:49:32,840 --> 00:49:35,600
Speaker 1: this new quantum thing. You can tell a story about

1043
00:49:35,600 --> 00:49:37,640
Speaker 1: it as if it was a new force.

1044
00:49:38,000 --> 00:49:39,880
Speaker 5: Okay, I think maybe I'm starting to get it. So

1045
00:49:40,040 --> 00:49:42,799
Speaker 5: like if I have two particles of dark matter, and

1046
00:49:42,840 --> 00:49:45,480
Speaker 5: I have them really far apart, then they do interact

1047
00:49:45,480 --> 00:49:47,600
Speaker 5: with each other, and not like they can't bump into

1048
00:49:47,680 --> 00:49:50,759
Speaker 5: each other, but they can attract each other gravitationally, like

1049
00:49:50,800 --> 00:49:54,200
Speaker 5: there's a gravitational force between the two particles of dark matter.

1050
00:49:54,239 --> 00:49:55,799
Speaker 5: I think what you're saying is when you bring them

1051
00:49:55,880 --> 00:49:57,960
Speaker 5: really really close to each other, so that wave function

1052
00:49:58,080 --> 00:50:00,960
Speaker 5: of these two dark matter particles starts overlapped, and there

1053
00:50:00,960 --> 00:50:04,200
Speaker 5: are other effects that start to kick in, other quantum

1054
00:50:04,239 --> 00:50:07,359
Speaker 5: effects then maybe affect the gravity between them.

1055
00:50:07,400 --> 00:50:09,879
Speaker 1: Yeah, that's precisely it. And you can talk about those

1056
00:50:09,920 --> 00:50:13,520
Speaker 1: new quantum effects as a new force and introduce even

1057
00:50:13,600 --> 00:50:16,520
Speaker 1: like new particles for that force. They call these things phonons.

1058
00:50:17,040 --> 00:50:20,480
Speaker 1: Or you could just say, maybe that changes the overall

1059
00:50:20,520 --> 00:50:24,600
Speaker 1: effective gravity, right, It changes the impact of gravity because

1060
00:50:24,600 --> 00:50:26,520
Speaker 1: now you have to factor in this new weird quantum

1061
00:50:26,560 --> 00:50:28,680
Speaker 1: effect and the amazing thing that comes out of the

1062
00:50:28,719 --> 00:50:31,160
Speaker 1: math is that the change it makes to gravity is

1063
00:50:31,200 --> 00:50:34,879
Speaker 1: to make it look exactly like mind predicts. So remember, mind,

1064
00:50:35,000 --> 00:50:39,520
Speaker 1: is this change in Newtonian gravity that would beautifully describe

1065
00:50:39,560 --> 00:50:41,760
Speaker 1: everything we see at the hearts of galaxies, but fails

1066
00:50:41,760 --> 00:50:44,279
Speaker 1: everywhere else. We turns out, if you make dark matter

1067
00:50:44,320 --> 00:50:48,120
Speaker 1: a superfluid, it changes the gravity within this dark matter

1068
00:50:48,239 --> 00:50:49,720
Speaker 1: to make it look just like mind.

1069
00:50:50,040 --> 00:50:52,800
Speaker 5: Wait, I thought that you know the gravity The gravity's

1070
00:50:52,840 --> 00:50:55,760
Speaker 5: just between the two particles, right, Like, the gravity between

1071
00:50:55,800 --> 00:50:58,239
Speaker 5: these two dark matter particles maybe changes when you bring

1072
00:50:58,280 --> 00:51:01,200
Speaker 5: them closer together, so that maybe they feel or not

1073
00:51:01,280 --> 00:51:04,399
Speaker 5: feel more or less gravity. But to someone standing far

1074
00:51:04,440 --> 00:51:08,319
Speaker 5: away from these two particles, why would the gravity change

1075
00:51:08,320 --> 00:51:08,600
Speaker 5: for them?

1076
00:51:08,760 --> 00:51:10,560
Speaker 1: No, it doesn't. You're absolutely right. And so if you're

1077
00:51:10,600 --> 00:51:13,520
Speaker 1: outside of a galaxy, it doesn't matter whether the dark

1078
00:51:13,560 --> 00:51:16,360
Speaker 1: matter is fluid or not. But we're talking about inside

1079
00:51:16,360 --> 00:51:19,399
Speaker 1: of a galaxy. We're talking about what's happening internally, how

1080
00:51:19,440 --> 00:51:22,800
Speaker 1: fast things are spinning, the gravity that like, one blob

1081
00:51:22,840 --> 00:51:25,040
Speaker 1: of dark matter is feeling on another blob of dark

1082
00:51:25,040 --> 00:51:28,919
Speaker 1: matter inside the same galaxy. So this affects how dark

1083
00:51:28,960 --> 00:51:31,400
Speaker 1: matter inside the Milky Way for example, is pulling on

1084
00:51:31,480 --> 00:51:34,200
Speaker 1: other dark matter inside the Milky Way, which is exactly

1085
00:51:34,200 --> 00:51:37,360
Speaker 1: what keeps the whole galaxy together as it spins.

1086
00:51:37,920 --> 00:51:41,040
Speaker 5: To These quantum effects make the gravity stronger of the

1087
00:51:41,080 --> 00:51:42,560
Speaker 5: superfluid or weaker.

1088
00:51:42,719 --> 00:51:45,800
Speaker 1: It makes the gravity stronger, right, it enhances their gravity.

1089
00:51:46,120 --> 00:51:47,640
Speaker 5: What do you mean, like, do you know what the

1090
00:51:47,719 --> 00:51:50,080
Speaker 5: quantum effect is or are just kind of postulating that

1091
00:51:50,080 --> 00:51:53,600
Speaker 5: there's maybe some quantum effect that would make the gravity stronger.

1092
00:51:54,160 --> 00:51:56,799
Speaker 1: The quantum effect comes from these overlapping wave functions. And

1093
00:51:56,920 --> 00:51:58,680
Speaker 1: when you put it together and you do the math

1094
00:51:59,080 --> 00:52:01,960
Speaker 1: and you squeeze it theoretically sort of into the box

1095
00:52:02,040 --> 00:52:04,160
Speaker 1: of a force and say, how do I interpret this

1096
00:52:04,200 --> 00:52:07,600
Speaker 1: as a force. Then the calculations come out to predict

1097
00:52:07,600 --> 00:52:10,319
Speaker 1: a change in the force of gravity that looks just

1098
00:52:10,520 --> 00:52:13,400
Speaker 1: like the math you get from mind. It's not just speculation.

1099
00:52:13,680 --> 00:52:16,719
Speaker 1: You can go directly from these quantum effects to calculating

1100
00:52:16,920 --> 00:52:19,719
Speaker 1: the new effective force of gravity. And it looks just

1101
00:52:19,880 --> 00:52:22,680
Speaker 1: like Mond's prediction, which is as we know something that

1102
00:52:22,719 --> 00:52:24,439
Speaker 1: works very very well well.

1103
00:52:24,480 --> 00:52:26,120
Speaker 5: But I think what you're saying is that the super

1104
00:52:26,160 --> 00:52:30,760
Speaker 5: compact dark matter forms a superfluid which has stronger gravity

1105
00:52:30,840 --> 00:52:34,359
Speaker 5: between the dark matter particles that are in the superfluid.

1106
00:52:34,719 --> 00:52:37,440
Speaker 5: But with something outside of this superfluid, would it feel

1107
00:52:37,600 --> 00:52:39,120
Speaker 5: this extra gravity or not?

1108
00:52:39,280 --> 00:52:42,120
Speaker 1: Well, something inside the galaxy would, but something outside the

1109
00:52:42,160 --> 00:52:46,080
Speaker 1: galaxy wouldn't. Right, So something outside far far away other

1110
00:52:46,120 --> 00:52:48,960
Speaker 1: galaxies in the cluster wouldn't feel any change in the

1111
00:52:49,000 --> 00:52:51,200
Speaker 1: effective gravity. And that's key because we don't want to

1112
00:52:51,239 --> 00:52:53,719
Speaker 1: change the predictions for dark matter in the cluster that

1113
00:52:53,840 --> 00:52:56,400
Speaker 1: already works really really well. The way we see that

1114
00:52:56,480 --> 00:53:00,000
Speaker 1: galaxies rotate around each other, and big clusters of galaxies

1115
00:53:00,120 --> 00:53:03,440
Speaker 1: rotate around other clusters of galaxies. That's very well described

1116
00:53:03,640 --> 00:53:05,360
Speaker 1: by the dark matter theory. So we don't want to

1117
00:53:05,440 --> 00:53:08,480
Speaker 1: change that. So the superfluid thing only changes what happens

1118
00:53:08,560 --> 00:53:10,719
Speaker 1: inside galaxies, not between galaxies.

1119
00:53:10,920 --> 00:53:13,280
Speaker 5: So how would that explain what we talked about earlier

1120
00:53:13,400 --> 00:53:15,680
Speaker 5: was one of the shortcomings of dark matter, which is

1121
00:53:15,680 --> 00:53:18,319
Speaker 5: that the proportion of dark matter and regular matter is

1122
00:53:18,360 --> 00:53:21,359
Speaker 5: too consistent between galaxies. How would this explain it?

1123
00:53:21,680 --> 00:53:23,840
Speaker 1: Well? Conceptually, you can imagine that it gives us a

1124
00:53:23,880 --> 00:53:25,920
Speaker 1: way for like dark matter and normal matter sort of

1125
00:53:25,920 --> 00:53:29,080
Speaker 1: talk to each other more intimately, So effectively it solves

1126
00:53:29,080 --> 00:53:31,920
Speaker 1: a problem by saying you do still have some variation

1127
00:53:32,040 --> 00:53:33,960
Speaker 1: in how much dark matter and normal matter you have.

1128
00:53:34,520 --> 00:53:37,120
Speaker 1: But dark matter itself acts a little bit differently, so

1129
00:53:37,160 --> 00:53:40,560
Speaker 1: it changes how galaxies rotate. It changes the effective gravity

1130
00:53:41,000 --> 00:53:43,959
Speaker 1: of that dark matter, and that's what determines how fast

1131
00:53:44,040 --> 00:53:47,400
Speaker 1: a galaxy can rotate without tearing itself apart. Remember the

1132
00:53:47,400 --> 00:53:49,759
Speaker 1: discrepancy we saw it was not actually directly in the

1133
00:53:49,880 --> 00:53:52,920
Speaker 1: dark matter density of these galaxies, but the rotation speed

1134
00:53:52,960 --> 00:53:56,120
Speaker 1: of the galaxies versus their brightness. So now we have

1135
00:53:56,160 --> 00:53:58,960
Speaker 1: a new way for dark matter and normal matter to

1136
00:53:58,960 --> 00:54:01,600
Speaker 1: interact a little bit more more strongly because this new

1137
00:54:01,680 --> 00:54:04,600
Speaker 1: force that's inside the dark matter superfluid. So we think

1138
00:54:04,600 --> 00:54:07,439
Speaker 1: that's sort of like couples the stars and the dark

1139
00:54:07,480 --> 00:54:10,080
Speaker 1: matter a little bit more tightly. It makes it possible

1140
00:54:10,120 --> 00:54:12,960
Speaker 1: for them to have like more feedback mechanisms to potentially

1141
00:54:12,960 --> 00:54:15,360
Speaker 1: explain what we're seeing out there in the universe.

1142
00:54:15,520 --> 00:54:17,200
Speaker 5: I think what you're saying is that maybe there's like

1143
00:54:17,239 --> 00:54:20,880
Speaker 5: an extra effect here that comes from the superfluidity of

1144
00:54:21,000 --> 00:54:25,040
Speaker 5: dark matter that maybe makes it not random, right because

1145
00:54:25,239 --> 00:54:27,880
Speaker 5: before the problem was that we expected the ratio of

1146
00:54:27,960 --> 00:54:29,959
Speaker 5: dark matter and normal matter to be is a little

1147
00:54:29,960 --> 00:54:32,960
Speaker 5: bit more random, more variation. But maybe this special effects

1148
00:54:33,040 --> 00:54:35,520
Speaker 5: kind of acts in a way that gives you less variation.

1149
00:54:35,719 --> 00:54:38,160
Speaker 5: Like if you have more dark matter, it acts in

1150
00:54:38,160 --> 00:54:40,479
Speaker 5: a weight so that you have more regular matter as well.

1151
00:54:40,760 --> 00:54:43,120
Speaker 5: And if you have less dark matter, then maybe acts

1152
00:54:43,120 --> 00:54:44,839
Speaker 5: in a weight to give you less regular matter.

1153
00:54:44,960 --> 00:54:46,960
Speaker 1: Yeah, that's the kind of feedback effect we're looking for.

1154
00:54:47,239 --> 00:54:48,800
Speaker 1: What we see out there in the universe. This is

1155
00:54:49,160 --> 00:54:52,760
Speaker 1: strangely tight relationship between the dark matter and the normal matter.

1156
00:54:53,000 --> 00:54:55,759
Speaker 1: We didn't understand that if the only relationship between the

1157
00:54:55,760 --> 00:54:58,799
Speaker 1: two was this fairly weak gravity. But if gravity gets

1158
00:54:58,800 --> 00:55:02,640
Speaker 1: a little bit stronger, helps solve those problems. And more specifically,

1159
00:55:02,880 --> 00:55:06,600
Speaker 1: we see that the effective gravity inside these galaxies now

1160
00:55:06,640 --> 00:55:10,280
Speaker 1: follows exactly the prediction of mind, which, as we said before,

1161
00:55:10,480 --> 00:55:13,640
Speaker 1: predicts very precisely the ratio of these dark matter to

1162
00:55:13,680 --> 00:55:16,719
Speaker 1: normal matter inside the galaxies. So it all clicks very

1163
00:55:16,800 --> 00:55:17,640
Speaker 1: nicely into place.

1164
00:55:18,520 --> 00:55:23,080
Speaker 5: M seems like a pretty super idea, this super fluid,

1165
00:55:23,520 --> 00:55:25,839
Speaker 5: but it also sort of constrains dark matter in a bit, right,

1166
00:55:25,880 --> 00:55:29,719
Speaker 5: like it depends also like it can only be a

1167
00:55:29,760 --> 00:55:32,799
Speaker 5: superfluid if dark matter is made out of really light

1168
00:55:32,920 --> 00:55:34,200
Speaker 5: small particles, right.

1169
00:55:34,520 --> 00:55:36,719
Speaker 1: And there are ideas out there for dark matter to

1170
00:55:36,840 --> 00:55:39,640
Speaker 1: be very very light particles. The most common idea is

1171
00:55:39,680 --> 00:55:43,399
Speaker 1: a WIMP, a weekly interacting massive particle where the mass

1172
00:55:43,400 --> 00:55:45,560
Speaker 1: of the particle would be like one hundred times the

1173
00:55:45,600 --> 00:55:48,279
Speaker 1: mass of the proton. But there are other ideas where

1174
00:55:48,360 --> 00:55:50,719
Speaker 1: dark matter could be very very light. We've talked about

1175
00:55:50,719 --> 00:55:53,320
Speaker 1: it before on the podcast, the idea of an axion

1176
00:55:53,600 --> 00:55:55,279
Speaker 1: sort of like a photon with a little bit of

1177
00:55:55,400 --> 00:55:57,799
Speaker 1: mass to it, And so this idea is a little

1178
00:55:57,800 --> 00:56:00,200
Speaker 1: bit more like an axion than a WIMP.

1179
00:56:00,239 --> 00:56:03,880
Speaker 5: Which would also maybe make dark matter harder to eventually

1180
00:56:03,960 --> 00:56:05,680
Speaker 5: detect and study right directly.

1181
00:56:06,080 --> 00:56:08,600
Speaker 1: Yeah, a lot of our searches for dark matters, these

1182
00:56:08,640 --> 00:56:11,520
Speaker 1: big underground tanks that are looking for a dark matter

1183
00:56:11,560 --> 00:56:14,440
Speaker 1: particle to come and bounce off a xenon atom, for example,

1184
00:56:14,600 --> 00:56:17,600
Speaker 1: are not capable of sensing dark matter at very very

1185
00:56:17,640 --> 00:56:20,840
Speaker 1: low mass. But we have other experiments that are looking

1186
00:56:20,840 --> 00:56:23,279
Speaker 1: for very very low mass dark matter particles. But there

1187
00:56:23,280 --> 00:56:25,839
Speaker 1: are also other ways to test this theory. People think

1188
00:56:25,880 --> 00:56:28,680
Speaker 1: that if this is true, it will also affect like

1189
00:56:28,840 --> 00:56:32,280
Speaker 1: how galaxies merge. I mean, if you have two merging

1190
00:56:32,320 --> 00:56:35,680
Speaker 1: galaxies and they each have their own halo of dark matter,

1191
00:56:36,120 --> 00:56:38,640
Speaker 1: then what happens when they emerge? You will see this

1192
00:56:38,760 --> 00:56:42,680
Speaker 1: superfluidity effect because the haloes won't merge as fast as

1193
00:56:42,719 --> 00:56:45,960
Speaker 1: they would otherwise. Like two haloes made of a normal fluid,

1194
00:56:46,080 --> 00:56:48,680
Speaker 1: you'll expect a little bit of friction. Two haloes made

1195
00:56:48,719 --> 00:56:52,160
Speaker 1: of a superfluid that'll basically pass through each other, and

1196
00:56:52,160 --> 00:56:54,359
Speaker 1: it'll be gravity that pulls them back, so they would

1197
00:56:54,400 --> 00:56:58,399
Speaker 1: like oscillate more times as they merge. If it's a superfluid,

1198
00:56:58,600 --> 00:57:00,879
Speaker 1: then if it's just a fluid, So if we can

1199
00:57:01,120 --> 00:57:04,400
Speaker 1: study merging galaxies as a chance, we can see whether

1200
00:57:04,560 --> 00:57:07,400
Speaker 1: dark matter is a superfluid or a normal fluid.

1201
00:57:09,080 --> 00:57:11,120
Speaker 5: I think we're saying is that the dark matter at

1202
00:57:11,120 --> 00:57:13,880
Speaker 5: the outsides and the edges of the galaxy, which is

1203
00:57:13,880 --> 00:57:17,280
Speaker 5: not as compact or superfluid, would sort of become a

1204
00:57:17,280 --> 00:57:19,680
Speaker 5: superfluid once it crashes into another galaxy.

1205
00:57:20,160 --> 00:57:22,840
Speaker 1: I'm saying that we can test the superfluidity of dark

1206
00:57:22,880 --> 00:57:26,160
Speaker 1: matter by slamming it into another blob of superfluid dark matter.

1207
00:57:26,360 --> 00:57:29,160
Speaker 1: If it really is superfluid, it should basically pass right through.

1208
00:57:29,400 --> 00:57:32,240
Speaker 1: If it isn't superfluid, then we should see some friction

1209
00:57:32,400 --> 00:57:34,760
Speaker 1: between the two blobs of dark matter. And we can't

1210
00:57:34,800 --> 00:57:38,360
Speaker 1: do this very easily, but sometimes galaxies collide right, huge

1211
00:57:38,400 --> 00:57:42,960
Speaker 1: galaxies slam into other galaxies, basically testing this hypothesis, doing

1212
00:57:43,000 --> 00:57:46,760
Speaker 1: this experiment of slamming one blob of dark matter into another.

1213
00:57:46,880 --> 00:57:48,800
Speaker 1: So if we can study those collisions, we might be

1214
00:57:48,840 --> 00:57:52,360
Speaker 1: able to tell the difference between superfluid collisions and normal

1215
00:57:52,400 --> 00:57:54,800
Speaker 1: fluid collisions because they should look a little bit different.

1216
00:57:54,920 --> 00:57:57,520
Speaker 5: Pretty interesting to think that dark matter, which we can

1217
00:57:57,880 --> 00:58:01,400
Speaker 5: see or touch, could be doing things that we can

1218
00:58:01,560 --> 00:58:04,840
Speaker 5: maybe imagine and even the dunk right and figure.

1219
00:58:04,600 --> 00:58:06,800
Speaker 1: Out yeah, because we can't see the dark matter directly,

1220
00:58:06,840 --> 00:58:09,560
Speaker 1: but we can see it indirectly because of gravitational lensing

1221
00:58:09,800 --> 00:58:12,800
Speaker 1: and because of its impact on the other stars. So

1222
00:58:12,960 --> 00:58:15,600
Speaker 1: doing a lot of statistics and very careful measurements, we

1223
00:58:15,640 --> 00:58:17,480
Speaker 1: can get a sense for where the dark matter is

1224
00:58:17,520 --> 00:58:19,400
Speaker 1: and what's happened to it, And then we can check

1225
00:58:19,440 --> 00:58:21,800
Speaker 1: that against our calculations and see does it look like

1226
00:58:21,840 --> 00:58:24,120
Speaker 1: it's being a super fluid or a normal fluid?

1227
00:58:24,480 --> 00:58:24,720
Speaker 13: Right?

1228
00:58:24,800 --> 00:58:26,400
Speaker 5: And if you see that it has a cape on it,

1229
00:58:26,440 --> 00:58:29,120
Speaker 5: then you know like, hey, it definitely has superpowers, right.

1230
00:58:29,000 --> 00:58:30,880
Speaker 1: That's right, and then it needs to stop buy our

1231
00:58:30,920 --> 00:58:34,320
Speaker 1: food truck so it can promote our superfluid beverages.

1232
00:58:34,160 --> 00:58:37,840
Speaker 5: Which we has not quite passed the PDA approval rate.

1233
00:58:39,240 --> 00:58:42,280
Speaker 1: That's right. Don't go at drinking any superfluid yet, please people.

1234
00:58:42,360 --> 00:58:44,919
Speaker 5: Yeah, and don't invite Daniel to your lab. Caacy will

1235
00:58:44,960 --> 00:58:48,040
Speaker 5: definitely put his own superfluids on everything.

1236
00:58:49,720 --> 00:58:51,640
Speaker 1: Hey, I'm a curious person, what can I say?

1237
00:58:51,680 --> 00:58:54,680
Speaker 5: All right? Well, another interesting idea about dark matter and

1238
00:58:54,720 --> 00:58:56,959
Speaker 5: the one that could explain what is going on out there,

1239
00:58:57,000 --> 00:59:00,560
Speaker 5: and another example of how this is still working. We

1240
00:59:00,600 --> 00:59:02,640
Speaker 5: don't know what this thing is. We're trying to figure

1241
00:59:02,680 --> 00:59:05,160
Speaker 5: it out, and there are still new ideas coming up

1242
00:59:05,200 --> 00:59:06,880
Speaker 5: that could explain what's going on.

1243
00:59:07,080 --> 00:59:09,640
Speaker 1: Yeah, there are whole categories of ideas. Some of them

1244
00:59:09,720 --> 00:59:12,560
Speaker 1: even try to combine dark matter with moond and say,

1245
00:59:12,720 --> 00:59:15,560
Speaker 1: maybe dark matter is real, but also gravity needs to

1246
00:59:15,600 --> 00:59:17,960
Speaker 1: be modified. Lots of people out there are trying to

1247
00:59:18,000 --> 00:59:20,120
Speaker 1: make the best of both worlds, and this is like

1248
00:59:20,200 --> 00:59:22,920
Speaker 1: a cool alternative to try to capture all of the

1249
00:59:22,920 --> 00:59:24,560
Speaker 1: best bits of all of those theories.

1250
00:59:24,920 --> 00:59:27,720
Speaker 5: You could make a Darkmond to the theory, right.

1251
00:59:27,760 --> 00:59:29,760
Speaker 1: Yeah, we could have a darkmond flavored coke.

1252
00:59:29,920 --> 00:59:33,080
Speaker 5: There you go, And you can make a darkmond sun

1253
00:59:33,200 --> 00:59:36,040
Speaker 5: ice cream Sunday as well. All right, Well, we hope

1254
00:59:36,040 --> 00:59:39,280
Speaker 5: you enjoyed that Thanks for joining us, See you next time.

1255
00:59:47,080 --> 00:59:49,880
Speaker 1: Thanks for listening, and remember that. Daniel and Jorge Explain

1256
00:59:49,960 --> 00:59:53,960
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts

1257
00:59:53,960 --> 00:59:58,600
Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

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1269
01:00:45,200 --> 01:00:48,160
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1270
01:00:48,240 --> 01:00:51,960
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1272
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