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Speaker 1: Hey, Daniel, are you glad our universe has antimatter?

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Speaker 2: No, I'm definitely pro our universe. So I guess I'm

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Speaker 2: not anti antimatter.

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Speaker 1: That means your pro matter. But I guess the question is,

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Speaker 1: would you miss antimatter if we didn't have it?

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Speaker 2: I mean, I like things the way they are, so

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Speaker 2: if we lost antimatter, the universe would be pretty different

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Speaker 2: and maybe worse. But what if it's better, or maybe

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Speaker 2: it couldn't exist without antimatter and it would disappear in

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Speaker 2: a puff of mathematical contradictions.

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Speaker 1: Okay, then I would be anti antimatter. I would not

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Speaker 1: be pro antimatter.

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Speaker 2: I'm just saying it matters. Hi.

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Speaker 1: I'm Boria mccartoonist and the creator of PhD Comics.

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Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor

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Speaker 2: at UC Irvine, and I love all the kinds of

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Speaker 2: matter out there, the matter and the antimatter and the

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Speaker 2: pro matter.

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Speaker 1: What about the meh matter? Not pro, not anti, It's

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Speaker 1: it's just kind of there.

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Speaker 2: You know. I will admit that there are some particles

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Speaker 2: I think they're exciting. In other particles, I'm like, yeah,

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Speaker 2: that's just a mess.

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Speaker 1: About your favorite kind of matter is chocolate matters certainly

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Speaker 1: better than vanilla matter, karp matter, But anyways, welcome to

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Speaker 1: our podcast, Daniel and Jorge Explain the Universe, a production

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Speaker 1: of iHeartRadio.

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Speaker 2: In which we dig deep into all kinds of matter

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Speaker 2: out there that matters. We talk about the things that

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Speaker 2: make you up. We talk about the things that make

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Speaker 2: nothing up, and things that seem to exist for which

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Speaker 2: we do not yet understand. The whole universe is like

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Speaker 2: a jigsaw puzzle with lots of weirdly shaped pieces, and

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Speaker 2: our goal is to find all those pieces, fit them

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Speaker 2: together to tell the whole story of our universe. And

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Speaker 2: on this podcast we'd like to do that and try

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Speaker 2: to explain all of it to you.

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Speaker 1: That's right. It is a vast and complicated universe, full

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Speaker 1: of all kinds of crazy and interesting kinds of matter

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Speaker 1: and energy and concepts and mathematics that we like to

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Speaker 1: explore as human beings and ask questions about and then

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Speaker 1: explain it to you, or at least ask you the question,

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Speaker 1: what's the matter with you?

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Speaker 2: We study all of these particles, we try to understand them,

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Speaker 2: and sometimes we even taste them to see if they're delicious.

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Speaker 2: But I wasn't joking when I said that some of

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Speaker 2: the particles out there are a little crazier and harder

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Speaker 2: to think about than others. I mean, there are so

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Speaker 2: many particles discovered in the era of the particle Zoo

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Speaker 2: that we almost ran out of silly Greek letters to

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Speaker 2: use to name all of them.

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Speaker 1: Oh boy, what happens when you run out of Greek letters?

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Speaker 2: Then you start using Hebrew letters? Okay, like the Gimmel

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Speaker 2: particle on the aleph particle. H interesting, But we've discovered

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Speaker 2: so many weird masons and baryons that we had to

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Speaker 2: use some of those weird Greek letters that nobody even

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Speaker 2: really knows how to write down.

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Speaker 1: I guess we have done a pretty good job of

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Speaker 1: kind of looking out into the universe and basically talent

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Speaker 1: up all the different kinds of matter, all the different

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Speaker 1: kinds of particles that can't exist out there, because there

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Speaker 1: are a lot. As you're saying, there are.

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Speaker 2: A lot, and it's sort of a two step process

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Speaker 2: to understand the universe. Like number one, just look out

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Speaker 2: and see what's there. Gather together all the puzzle pieces.

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Speaker 2: Number two, try to click them together to tell the

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Speaker 2: whole story. Are there pieces missing, do they fit together

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Speaker 2: into a puzzle or is it just a weird, disjointed

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Speaker 2: pile of confusion.

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Speaker 1: Yeah, And I guess the history of it is that

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Speaker 1: we used to think that we knew what the building

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Speaker 1: blocks of the universe was, right. We thought the elements

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Speaker 1: of the periodic table were like the basic lego pieces

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Speaker 1: of the universe. But actually those turned to be made

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Speaker 1: of other things. And then those some of those things

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Speaker 1: turn to be made of other things.

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Speaker 2: That's right. We revealed this sort of hierarchical structure of matter,

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Speaker 2: things made of smaller things, made of smaller things, but

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Speaker 2: the path to understand them in the history of science

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Speaker 2: was not so straightforward. We sort of like drilled down

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Speaker 2: and then got wider and weirder, and then drilled down

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Speaker 2: again and got wider and weirder. For example, when we

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Speaker 2: wanted to understand the nucleus, when we wanted to understand

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Speaker 2: protons and neutrons and what's inside them, we'd build bigger

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Speaker 2: atom smashers and higher energy colliders, but we didn't immediately

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Speaker 2: find out what was inside the proton. Instead, first we

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Speaker 2: discovered all sorts of weird other kinds of particles that

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Speaker 2: don't exist inside the atom, chaons and pions and rope

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Speaker 2: particles and omega particles and all sorts of other Greek letters.

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Speaker 2: I don't even know how to pronounce. Things got weird

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Speaker 2: before they got clearer.

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Speaker 1: Yeah, no, I understand. It's all Greek to me.

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Speaker 2: In the same way that we want to understand what's

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Speaker 2: inside the quarks that make up the proton, but first

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Speaker 2: we found more quarks along the way. Instead of figuring

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Speaker 2: out what's inside the upcork and the down cork, we

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Speaker 2: found the charm and the strange, and the top and

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Speaker 2: the bottom. So the universe gives us a big pile

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Speaker 2: of clues before it reveals its deepest secrets.

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Speaker 1: Yeah, it is a weird universe full of surprises. And

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Speaker 1: one of the weirdest things about matter in the universe

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Speaker 1: is that it seems to have an opposite to it.

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Speaker 1: There seems to be a lot of antimatter in the universe.

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Speaker 2: Every particle out there seems to have its weird twin.

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Speaker 2: And we don't know if this is a detour in

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Speaker 2: our path to finally understanding what is the fundamental nature

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Speaker 2: of matter, or if it's a crucial side quest to

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Speaker 2: get a clue that will help us unlock the deepest mystery.

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Speaker 2: We don't know if and of matter is necessary, we

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Speaker 2: don't know what role it plays, We don't really know

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Speaker 2: what clue it's giving us about the nature of the universe.

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Speaker 1: And so to the other podcast, we'll be asking the

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Speaker 1: question why do we have anti particles? Feel like that's

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Speaker 1: a weird double negative question, like why don't we have particles?

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Speaker 1: Or why do we have anti particles? What's the correct

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Speaker 1: grammar here or is it in Greek?

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Speaker 2: I think why do we have anti particles? Is the

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Speaker 2: deep question? You know, every time we see something in

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Speaker 2: the universe, we wonder like, hmmm, did it have to

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Speaker 2: be this way? Is this necessary? Is this a clue

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Speaker 2: as to the fundamental nature of the universe or just

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Speaker 2: sort of like a random accident.

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Speaker 1: Well, so, as usual, we were wondering how many people

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Speaker 1: out there had thought about this question or have any

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Speaker 1: ideas about why we have anti particles.

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Speaker 2: So thank you very much to everybody who answers these

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Speaker 2: questions for this fun segment of our podcast. If you

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Speaker 2: would like to play along next time, please don't be shy.

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Speaker 2: Write to me two questions at Danielandjorge dot Com.

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

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Speaker 1: think we have anti particles? Here's what people had to say.

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Speaker 3: In general, antiparticles exist because particles exist and there's some

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Speaker 3: sort of balance that was broken at.

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Speaker 1: The Big Bang.

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Speaker 4: I don't know, but the universe seems to like symmetry,

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Speaker 4: and somehow antiparticles had to exist for some kind of

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Speaker 4: symmetry to be to be fulfilled. But I don't know.

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Speaker 4: It's kind of crazy.

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Speaker 1: I think anti particles exist for the same reason you

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Speaker 1: don't get monopole magnets.

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Speaker 2: But I'm got clear, so we'll say with me, well

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Speaker 2: maybe not.

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Speaker 3: I feel like you need the antiparticles like cancel it out,

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Speaker 3: because you can't have like something from nothing. You need

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Speaker 3: to have something and then the opposite of it, so

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Speaker 3: that like overall nothing has changed.

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Speaker 5: Any particles are probably like the ying and yang. For

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Speaker 5: every particle, there has to exist an anti particle in

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Speaker 5: order to balance the forces in the universe, similar to

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Speaker 5: matter and anti matter.

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Speaker 6: I think the reason why antiparticles exist is because everything

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Speaker 6: in nature and physics seems to be balanced. So if

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Speaker 6: you sum up everything, it comes off like zero. But yeah,

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Speaker 6: for everything that exists, there needs to be an anti

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Speaker 6: thing Somemari like Ying and Young.

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Speaker 1: All right, some very philosophical answers here, some of them

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Speaker 1: kind of zen.

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Speaker 2: Yeah, there's a lot of philosophy in these questions, you know,

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Speaker 2: wondering whether the universe could have multiple explanations or just

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Speaker 2: one explanation, or whether it has any explanation at all,

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Speaker 2: whether it makes sense, and whether it's sensible to human minds.

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Speaker 2: All that stuff is tied up in this quest to

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Speaker 2: understand the universe.

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Speaker 1: Do you think maybe there are anti particle scientists out

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Speaker 1: there and or cartoonists we're wondering why do we have particles?

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Speaker 1: What is this weird stuff?

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Speaker 2: I don't know, but humans are capable of developing science

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Speaker 2: as well as antiscience. More recently, I'm.

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Speaker 1: Just antiphysics, I like all the other sciences.

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Speaker 2: Are you antiphysics or are you anti physicists?

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Speaker 1: I'm anti answering that question and that's an answer to

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Speaker 1: that a position there. Well, let's dig into it, Daniel Water,

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Speaker 1: anti particles is it like antimatter exactly?

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Speaker 2: Anti particles are what make up anti matter. So matter

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Speaker 2: is the stuff that we find around us that you

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Speaker 2: were made of. That I am made out of everything

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Speaker 2: you have ever eaten is made out of particles that

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Speaker 2: we call matter particles. So you and I are made

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Speaker 2: out of protons, neutrons, and electrons, and those protons and

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Speaker 2: neutrons are made up of quarks. Anti matter is made

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Speaker 2: up of anti particles, so you could have, for example,

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Speaker 2: anti hydrogen is made of an anti proton and an

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Speaker 2: anti electron, where the anti proton is then made of

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Speaker 2: anti quarks. So there's a close connection, of course between

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Speaker 2: anti matter and anti particles.

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Speaker 1: I see. So particles are the little things that we're

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Speaker 1: all made out of, and some of them have anti

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Speaker 1: versions of them. Do all particles have anti versions or

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Speaker 1: only some of them? Like do the force particles have

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Speaker 1: anti force particles?

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Speaker 2: Great question, sort of yes and no. All the particles

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Speaker 2: have anti particles, but some of them are their own

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Speaker 2: anti particles, so I'm not sure if that counts as

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Speaker 2: having an anti particle. So, for example, the electron has

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Speaker 2: an antiparticle the positron, and the muon has an anti

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Speaker 2: particle the anti muon, and the quarks have antiparticles the

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Speaker 2: anti quarks. Those are different particles, or you could think

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Speaker 2: of them as two parts of the same pair. But

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Speaker 2: they are distinct states. But then particles, like you said,

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Speaker 2: the force carrying particles like the photon, the photon is

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Speaker 2: its own anti particle, and so you might also say

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Speaker 2: it doesn't have an anti particle. But I'd like to

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Speaker 2: think about it as one particle playing two roles.

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Speaker 1: What about some of the other force particles, do they

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Speaker 1: have anti versions?

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Speaker 2: Well, there are two w bosons, and they are each

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Speaker 2: other's antiparticles. So you have the W plus and the

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Speaker 2: W minus for example. So those two force particles are

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Speaker 2: each other's anti particles, which is why we have two

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Speaker 2: of them. The Z boson is its own antiparticle, and

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Speaker 2: the gluon is actually eight gluons, all of different colors,

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Speaker 2: and some of them are each other's antiparticles. So you

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Speaker 2: can have like a red anti green gluon, which is

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Speaker 2: the antiparticle to the anti red green gluon. It gets

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Speaker 2: really colorful with gluons.

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Speaker 1: Well, I feel bad for those particles that are their

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Speaker 1: own anti versions of themselves. It's like they're their own

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Speaker 1: worst enemies.

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Speaker 2: Or maybe they're lonely. Right, one is the loneliest number.

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Speaker 1: After all, this should hang out together.

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Speaker 2: Some people confuse anti matter with dark matter, And there's

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Speaker 2: lots of mysteries in particle physics, right, lots of things

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Speaker 2: that we don't understand about the universe, But those are

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Speaker 2: two separate mysteries. Dark matter is the invisible matter that's

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Speaker 2: out there in the universe that we know is holding

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Speaker 2: galaxies together and shaping the whole development of the large

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Speaker 2: scale structure of the universe. We don't know what it is,

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Speaker 2: and if it's made of particles, that's a different idea

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Speaker 2: from antimatter. Antimatter is a real thing that we can make,

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Speaker 2: that we can study. We've seen it in our detectors.

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Speaker 2: We know for sure that it exists and it's made

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Speaker 2: of anti particles.

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Speaker 1: Well, I guess maybe the question now is how do

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Speaker 1: you make antimatter? Can you make it or does it

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Speaker 1: exist in nature or is it just a matter of

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Speaker 1: like flipping the sign on some quantum property of regular particles.

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Speaker 2: So sort of all of the above. Antimatter isn't very common.

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Speaker 2: The universe is almost entirely made of matter, meaning it's

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Speaker 2: made of particles instead of anti particles, but sometimes antimatter

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Speaker 2: is produced, though it doesn't last very long because it

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Speaker 2: runs into normal particles and annihilates but for example, the

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Speaker 2: discovery of anti I mapps, which led to the nineteen

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Speaker 2: thirty three Nobel Prize, was from naturally produced antimatter. So

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Speaker 2: a positron the opposite particle to an electron produced in

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Speaker 2: cosmic rays, meaning high energy collisions of particles from space

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Speaker 2: hitting the upper atmosphere and creating antimatter which then showered

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Speaker 2: down to the surface of the Earth.

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Speaker 1: So when was this When was the first time we

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Speaker 1: saw antimatter?

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Speaker 2: So it was first observed in the late nineteen twenties.

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Speaker 2: It was predicted by Paul Durack, the quantum physicist, who

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Speaker 2: saw the mathematical need for them in his equations, and

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Speaker 2: he said, hm, my equations predict there should be electrons

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Speaker 2: and should also be another particle with the opposite charge

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Speaker 2: as the electron. So he predicted it, and then Carl

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Speaker 2: Anderson saw it. We have a whole fun podcast episode

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Speaker 2: about the discovery of antimatter and the twists and turns

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Speaker 2: and the egos involved. It's a really fun story. Check

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Speaker 2: that out. We've known about it for almost one hundred

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Speaker 2: years now.

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Speaker 1: It sort of involves cloud chambers, right, which is something

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Speaker 1: you can usually find in most science museums.

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Speaker 2: Yeah, early particle physics didn't have fancy digital electronics and

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Speaker 2: the complicated detectors we have now. They had to use

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Speaker 2: techniques to observe the paths of these particles with the

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Speaker 2: technology they had. And one thing you can do to

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Speaker 2: illuminate what particles are flying through the air around you

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Speaker 2: is to create clouds of water vapor. If you have

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Speaker 2: air that's super saturated with water, meaning it actually has

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Speaker 2: more water in it than it likes to have, then

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Speaker 2: it's very easy to knock that water out of the air,

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Speaker 2: and a passing charge particle will do just that and

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Speaker 2: will create a string of droplets in the air. You

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Speaker 2: can actually create cloud chambers at home. Check out lots

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Speaker 2: of YouTube videos for how to do this. You can

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Speaker 2: build one in your garage. You can see them at

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Speaker 2: science museums and so you can see high energy particles

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Speaker 2: streaming through the air around you, muons and all sorts

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Speaker 2: of stuff. Carl Anderson proved that a fraction of these

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Speaker 2: are actually anti matter particles, and he did that by

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Speaker 2: showing how they curve differently in magnetic fields. Because magnetic

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Speaker 2: fields will change the path of a charge particle depending

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Speaker 2: on the charge. A positive charge will be in it

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Speaker 2: one way. A negative charge will bend it the other way.

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Speaker 2: So he saw particles that had the same mass as electrons,

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Speaker 2: but bend in the other.

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Speaker 1: Direction like a positively charged electron. Is that basically what

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Speaker 1: an anti electron is, Just an electron with a charge flip.

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Speaker 2: Yeah, that's what antiparticles are. They're just like their particle counterparts,

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Speaker 2: but they have the opposite charges, so the opposite electric charge,

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Speaker 2: the opposite weak charges, and the opposite color charges. So

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Speaker 2: in the case of the electron, it's basically a positively

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Speaker 2: charged electron.

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Speaker 1: Right, because I guess an electron doesn't have the weak

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Speaker 1: charge and it doesn't have the strong charge.

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Speaker 2: Right, Electrons do have the weak charge. Actually, remember, the

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Speaker 2: weak force is actually unified with electromagnetism into one force

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Speaker 2: we call electro week, and electrons can interact via the

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Speaker 2: weak force. They can emit w's for example, that's how

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Speaker 2: beta decay happens. So electrons interact with the weak force.

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Speaker 2: In fact, every particle we've ever seen interacts with a

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Speaker 2: weak force, which is fascinating because the other forces are

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Speaker 2: not so democratic. The strong force only interacts with quarks

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Speaker 2: and not at all with electrons or neutrinos, and electromagnetism

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Speaker 2: doesn't interact with neutrinos. But we've never found a particle

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Speaker 2: that doesn't have any kind of weak charge. Every particle

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Speaker 2: out there so far we discovered interacts with the weak force.

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Speaker 1: Wait, what's the name of the week charge? If you

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Speaker 1: have a week charge, what is that called?

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Speaker 2: Well, there's actually two different week charges. One of them

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Speaker 2: is called weak isospin and the other one is called

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Speaker 2: weak hypercharge. But you can combine them actually to make

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Speaker 2: electromagnetic charge. So there's two different charges for the electro

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Speaker 2: weak force, but one of them is really from electromagnetism.

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Speaker 1: I'll pretend I totally understood that. But I guess when

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Speaker 1: you're trying to make an anti electron, which one do

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Speaker 1: you flip? Do you flip the electromagnetic charge like the

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Speaker 1: you know, plus and minds that we're all familiar with,

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Speaker 1: or do you flip one of these other sub charges?

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Speaker 1: And if you do, do I mean there are several

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Speaker 1: versions of an anti electron.

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Speaker 2: Now you flip all the charges. So there's only one

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Speaker 2: version of a positron, and it has a positive electric charge.

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Speaker 2: It also has both of its weak charges flipped.

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Speaker 1: But what if you flip one and the other you

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Speaker 1: can't do that, man, don't do that. They'll tell you

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Speaker 1: why not to do, tell you why I can't do it.

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Speaker 1: Then I can choose whether or not I can't.

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Speaker 2: I will do it. It's not me, man, it's the

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Speaker 2: laws of the universe. No, we do not see particles

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Speaker 2: where only one charge is flipped and the other one

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Speaker 2: is not.

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Speaker 1: Why not.

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Speaker 2: Yeah, that's a very cool question, imagining particles that are

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Speaker 2: particles according to one force and anti particles according to

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Speaker 2: another force. Remember, we recently answered a question about whether

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Speaker 2: it even matters whether you're calling something matter or antimatter,

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Speaker 2: and turns out that's totally an arbitrary distinction. So it

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Speaker 2: doesn't really matter if one force considers a particle matter

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Speaker 2: and the other one considers a particle the anti matter.

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Speaker 2: But the forces do have to be consistent, and in

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Speaker 2: the case of the weak force and electromagnetism, for example,

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Speaker 2: they are tightly linked, so you can't just flip one

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Speaker 2: and not the other. The charges of the two forces

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Speaker 2: really are connected by the structure of the theory.

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Speaker 1: I think what you're what you're saying, is this matter

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Speaker 1: anti matter distinction is really kind of arbitrary kind of right,

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Speaker 1: Like it's not as clear cut, like maybe there are

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Speaker 1: shades of gray or shades of antiness.

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Speaker 2: Yeah, we definitely don't claim to understand everything there is

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Speaker 2: to know about antimatter. But I think you're right A

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Speaker 2: lot of this comes down to just like what do

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Speaker 2: you call matter and what do you call antimatter. A

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Speaker 2: crucial idea is that there are these symmetries that you

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Speaker 2: can flip these charges and the equations still work, that

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Speaker 2: the universe can do both of these things, and so

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Speaker 2: it does in some cases. We have like multiple ways

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Speaker 2: to categorize what is matter and what is antimatter.

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Speaker 1: Well, I think the thing that most people probably remember

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Speaker 1: about antimatter, and that maybe is relevant here, is that

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Speaker 1: like a matter particle and it's antimatter particle, if they touch,

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Speaker 1: then they annihilate. They become pure energy. Right, We've talked

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Speaker 1: about that before they explode. That's one of the things

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Speaker 1: about antimatter.

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Speaker 2: Particles and their antiparticles can annihilate into a force particle.

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Speaker 2: So for example, an electron and a positron can come

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Speaker 2: together to make a photon or a z boson and

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Speaker 2: a and an anti quark can come together to make

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Speaker 2: a glue on, and the opposite can happen. Also, a

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Speaker 2: photon can turn into a matter antimatter pair, or a

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Speaker 2: z boson can decay into a muon and its anti particle.

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Speaker 1: But then I guess if anti nus is kind of

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Speaker 1: relative or there's a gray area there, or how does

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Speaker 1: that affect the annihilation? Like if I take a cork

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Speaker 1: and an antiquark, but I flip some other other signs,

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Speaker 1: do they still annihilate?

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Speaker 2: They can annihilate if there is a particle that carries

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Speaker 2: their combined charges. So for example, an electron and a

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Speaker 2: positron can annihilate because in total they have zero electric

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Speaker 2: charge and the photon has zero electric charge. That's why

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Speaker 2: an electron cannot annihilate with another electron, because then you'd

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Speaker 2: have to have a particle with a minus two charge

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Speaker 2: in order to conserve electric charge. So the same thing

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Speaker 2: goes for the other charges.

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Speaker 1: So like if I have a green cork and an

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Speaker 1: anti green cork, but a given different you know, regular charges,

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Speaker 1: what's gonna happen? Are they going to annihilate or repel

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Speaker 1: each other? Or what I'm just trying to get at,

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Speaker 1: Like what it means to be anti mime. Is it

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Speaker 1: depending on this annihilation thing or is it kind of random.

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Speaker 2: It's a little bit more complicated for the color charge

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Speaker 2: because gluons themselves are colored. You know, the photons don't

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Speaker 2: have any charge for example, right, so it's simple plus

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Speaker 2: and minus annihilate to zero charge photons. In the case

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Speaker 2: of gluons, gluons do carry color. In fact, they carry

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Speaker 2: two colors, which is even more confusing. So for example,

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Speaker 2: a red anti green quark can combine to make red

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Speaker 2: anti green gluon. The glue on itself carries two of

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Speaker 2: those colors, but the gluons don't carry electric charge, so

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Speaker 2: this can only happen for quarks that have opposite electric

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Speaker 2: charges that can balance out to zero electric charge. So

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Speaker 2: one way to think about how to pair particles and

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Speaker 2: antiparticles is whether they can annihilate into these force particles.

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Speaker 1: I see, So maybe one particle can have multiple anti

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Speaker 1: versions of itself.

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Speaker 2: There are definitely multiple different versions of quarks that an

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Speaker 2: individual quark can annihilate with to create a gluon. Because

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Speaker 2: there are so many different kinds of gluons, they always

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Speaker 2: have to have opposite electric charges. Because the gluons don't

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Speaker 2: have electric charge, So yeah, it gets really complicated when

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Speaker 2: you're talking about the color charges because there's multiple different

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Speaker 2: color charges and the gluons carry them themselves, and so

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Speaker 2: the whole thing is a big mess.

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Speaker 1: Is that how you end every physics paper? YadA YadA,

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Speaker 1: YadA YadA, And it's all a big mess.

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Speaker 2: It's a big mess, and it's a glorious puzzle and

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Speaker 2: we're still working to try to figure it out. Yeah.

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Speaker 1: Cool, Well, I guess the big question is still why

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Speaker 1: do we have anti particles at all? Why do they

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Speaker 1: exist in the universe? And so let's dig into that

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Speaker 1: question and some of the other open questions about antimatter.

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Speaker 1: But first let's take a quick break. All right, we're

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Speaker 1: talking about antimatter antiparticles and why do we need them

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Speaker 1: at all? Which sounds like a very insensitive question.

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Speaker 2: What the deepest question we ask when we see something

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Speaker 2: in the universe, We ask like, why is it this

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Speaker 2: way and not some other way? Does it have to

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Speaker 2: be this way? Is the universe parsimonious, like it only

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Speaker 2: contains things that have to happen? Or is it sort

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Speaker 2: of like baroque that has all sorts of flourishes that

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Speaker 2: it doesn't really need, and it's just sort of beautiful.

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Speaker 2: We tend to think of the universe as parsimonious. We

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Speaker 2: try to take every piece that we find and fit

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Speaker 2: it into the puzzle to explain why the universe works

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Speaker 2: this way.

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Speaker 1: Well, I guess one of the reasons we as we

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Speaker 1: talked about last time, that we call some things matter

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Speaker 1: and something's antimatter, is that we mostly see matter out

439
00:21:33,000 --> 00:21:34,840
Speaker 1: there in the universe, at least as far as we know.

440
00:21:35,359 --> 00:21:38,080
Speaker 1: Our planet, our Solar System, our galaxy is made out

441
00:21:38,080 --> 00:21:41,160
Speaker 1: of regular matter, and there's a big mystery about why

442
00:21:41,200 --> 00:21:44,080
Speaker 1: there isn't as much antimatter in the universe. But maybe

443
00:21:44,160 --> 00:21:46,879
Speaker 1: one question that you can ask is, like, is matter

444
00:21:46,920 --> 00:21:50,880
Speaker 1: and antimatter made at the same rate in the universe.

445
00:21:50,920 --> 00:21:53,560
Speaker 1: Like if you run a particle collision experiment and you

446
00:21:53,600 --> 00:21:57,200
Speaker 1: create some energy and some particles spill out to matter,

447
00:21:57,240 --> 00:22:00,199
Speaker 1: particles get made as much as antimatter particles.

448
00:22:00,200 --> 00:22:01,719
Speaker 2: A little bit on what you start from. I mean,

449
00:22:01,760 --> 00:22:04,359
Speaker 2: if you start from particles of matter, then you're going

450
00:22:04,400 --> 00:22:07,800
Speaker 2: to get more matter particles than antimatter particles. If you

451
00:22:07,840 --> 00:22:10,639
Speaker 2: start from antimatter particles, then you're going to get more antimatter,

452
00:22:10,680 --> 00:22:13,040
Speaker 2: and we actually ran a whole collider that smashed matter

453
00:22:13,200 --> 00:22:17,080
Speaker 2: versus antimatter. Now, was the collider outside Chicago, the Tevatron,

454
00:22:17,160 --> 00:22:21,080
Speaker 2: collided protons with anti protons, and so there we got

455
00:22:21,119 --> 00:22:25,440
Speaker 2: even splits of matter and antimatter. Whereas the collider at Cerne,

456
00:22:25,480 --> 00:22:29,840
Speaker 2: the Large Hadron Collider, smashes protons with protons because antimatter

457
00:22:30,040 --> 00:22:32,560
Speaker 2: was such a big headache to produce for the other collider,

458
00:22:32,960 --> 00:22:35,760
Speaker 2: And so there we get more matter produced than antimatter

459
00:22:35,760 --> 00:22:38,919
Speaker 2: because we're starting from matter. But most of these processes

460
00:22:39,000 --> 00:22:39,680
Speaker 2: are symmetric.

461
00:22:39,760 --> 00:22:39,879
Speaker 4: Right.

462
00:22:39,880 --> 00:22:41,840
Speaker 2: If you just have a big pile of photons and

463
00:22:41,920 --> 00:22:44,120
Speaker 2: you wait for them to decay, they will produce an

464
00:22:44,160 --> 00:22:46,960
Speaker 2: equal number of positrons and electrons.

465
00:22:47,640 --> 00:22:49,640
Speaker 1: I see. So I guess the big mystery is that

466
00:22:49,720 --> 00:22:53,080
Speaker 1: it sounds kind of like the universe is able to

467
00:22:53,119 --> 00:22:55,679
Speaker 1: make equal amounts of both kinds of matter, but what

468
00:22:55,720 --> 00:22:57,840
Speaker 1: we see in the universe is mostly only one kind

469
00:22:57,840 --> 00:22:58,200
Speaker 1: of matter.

470
00:22:58,320 --> 00:23:01,280
Speaker 2: Yeah, we suspect that the very early universe, matter and

471
00:23:01,320 --> 00:23:03,879
Speaker 2: antimatter were created at the same rates that as the

472
00:23:03,960 --> 00:23:07,560
Speaker 2: universe cooled down from the frothing pile of quantum fields

473
00:23:07,920 --> 00:23:10,400
Speaker 2: and things got cold and isolated enough that you could

474
00:23:10,440 --> 00:23:14,719
Speaker 2: call things particles, that the particles and anti particles existed

475
00:23:14,720 --> 00:23:16,720
Speaker 2: at basically the same level. Then there was a huge

476
00:23:16,760 --> 00:23:19,480
Speaker 2: amount of annihilation, as you can imagine, and most of

477
00:23:19,520 --> 00:23:22,280
Speaker 2: the matter and antimatter went away and turned into radiation.

478
00:23:22,520 --> 00:23:25,199
Speaker 2: But a little bit more matter is left over than antimatter,

479
00:23:25,240 --> 00:23:28,400
Speaker 2: and we don't understand the source of that discrepancy, even

480
00:23:28,440 --> 00:23:32,240
Speaker 2: though it's the reason why we have matter galaxies and matter,

481
00:23:32,320 --> 00:23:36,040
Speaker 2: stars and matter, people and matter chocolate and not anti matter.

482
00:23:36,480 --> 00:23:40,560
Speaker 2: The universe seems to have some preference for matter over antimatter.

483
00:23:40,160 --> 00:23:44,240
Speaker 1: Which makes me ask the question, is anti chocolate vanilla

484
00:23:44,359 --> 00:23:46,360
Speaker 1: or white chocolate or is it a case of having

485
00:23:46,440 --> 00:23:47,960
Speaker 1: multiple antiversities?

486
00:23:48,720 --> 00:23:50,600
Speaker 2: I hope so, because neither of those things should be

487
00:23:50,680 --> 00:23:51,760
Speaker 2: categorized with chocolate.

488
00:23:51,840 --> 00:23:54,800
Speaker 1: You're just pro chocolate. You just anti everything that's.

489
00:23:55,119 --> 00:23:57,560
Speaker 2: I'm just anti calling things chocolate that aren't chocolate. Even

490
00:23:57,600 --> 00:24:00,240
Speaker 2: calling them anti chocolate somehow groups them to get they're

491
00:24:00,280 --> 00:24:02,479
Speaker 2: in that chocolate category where they don't belong.

492
00:24:02,760 --> 00:24:05,680
Speaker 1: What about vegan chocolate, not chocolate.

493
00:24:05,400 --> 00:24:07,480
Speaker 2: No, totally chocolate. It comes from the cocoa bean.

494
00:24:07,560 --> 00:24:11,040
Speaker 1: Yeah, absolutely, all right, Well, the big question is why

495
00:24:11,080 --> 00:24:14,560
Speaker 1: does it exist? At all. Why do we have antimatter,

496
00:24:14,680 --> 00:24:17,480
Speaker 1: Like is it something that the equations of the universe

497
00:24:17,600 --> 00:24:21,000
Speaker 1: requires or is it just something that seems to happen.

498
00:24:21,800 --> 00:24:23,040
Speaker 1: That's the big question, right.

499
00:24:22,960 --> 00:24:25,520
Speaker 2: That's the question, and the short answer is we don't know.

500
00:24:26,200 --> 00:24:30,199
Speaker 2: But what's really fascinating is that without antimatter, some of

501
00:24:30,240 --> 00:24:33,600
Speaker 2: our basic theories of physics don't work very well together.

502
00:24:33,760 --> 00:24:37,120
Speaker 2: Like we have relativity and we have quantum mechanics, both

503
00:24:37,160 --> 00:24:40,359
Speaker 2: things that we think make sense in the universe, but

504
00:24:40,480 --> 00:24:43,280
Speaker 2: when we try to bring them together, we get some conflicts.

505
00:24:43,560 --> 00:24:46,919
Speaker 2: And it turns out that antimatter resolves those conflicts and

506
00:24:47,040 --> 00:24:51,200
Speaker 2: lets us bring special relativity and quantum mechanics together into

507
00:24:51,280 --> 00:24:51,959
Speaker 2: one theory.

508
00:24:52,119 --> 00:24:54,680
Speaker 1: Wait, I thought those two things didn't like each other.

509
00:24:54,840 --> 00:24:58,360
Speaker 2: So we have two different theories of relativity, special relativity,

510
00:24:58,520 --> 00:25:01,080
Speaker 2: which tells us about what happens and things move really

511
00:25:01,160 --> 00:25:04,640
Speaker 2: really fast near the speed of light, and then general relativity,

512
00:25:04,800 --> 00:25:08,160
Speaker 2: which tells us how space bends in the presence of mass.

513
00:25:08,480 --> 00:25:11,240
Speaker 2: General relativity and quantum mechanics we do not know how

514
00:25:11,280 --> 00:25:14,200
Speaker 2: to combine into a theory of quantum gravity. That's something

515
00:25:14,240 --> 00:25:16,720
Speaker 2: for a future physicist, maybe one of our listeners, to

516
00:25:16,840 --> 00:25:19,760
Speaker 2: figure out, but special relativity and quantum mechanics we do

517
00:25:19,880 --> 00:25:22,120
Speaker 2: know how to combine, and we've had that for many,

518
00:25:22,160 --> 00:25:26,520
Speaker 2: many decades. So that's basically relativistic quantum mechanics, and that

519
00:25:26,680 --> 00:25:28,800
Speaker 2: is something that we know how to do thinking about

520
00:25:28,880 --> 00:25:31,280
Speaker 2: quantum particles and moving near the speed of light, and

521
00:25:31,320 --> 00:25:33,560
Speaker 2: we do that all the time in our particle colliders, right,

522
00:25:33,560 --> 00:25:37,120
Speaker 2: it happens all the time that we have high speed particles.

523
00:25:37,200 --> 00:25:41,600
Speaker 2: So relativistic quantum mechanics we can do bend space, curved space.

524
00:25:41,680 --> 00:25:43,280
Speaker 2: Quantum mechanics we don't know how to do.

525
00:25:44,160 --> 00:25:48,840
Speaker 1: Interesting. Okay, So you're saying somehow antimatter and antiparticles somehow

526
00:25:48,960 --> 00:25:52,520
Speaker 1: make quantum mechanics and special relativity work together. What does

527
00:25:52,560 --> 00:25:52,840
Speaker 1: that mean?

528
00:25:52,920 --> 00:25:55,600
Speaker 2: So it all has to do with preserving causality, and

529
00:25:55,640 --> 00:25:59,520
Speaker 2: special relativity makes it really hard to think about causality,

530
00:25:59,640 --> 00:26:02,720
Speaker 2: to think about the order that things happen in the universe,

531
00:26:02,960 --> 00:26:05,159
Speaker 2: because it forces us to think about the order of

532
00:26:05,200 --> 00:26:08,440
Speaker 2: events in a very different way than like Newton thought

533
00:26:08,440 --> 00:26:11,080
Speaker 2: about things, and the way that we intuitively think about things.

534
00:26:11,200 --> 00:26:13,640
Speaker 2: You probably think about the universe happening as if there's

535
00:26:13,680 --> 00:26:16,479
Speaker 2: like a giant clock and the whole universe like ticks

536
00:26:16,520 --> 00:26:19,040
Speaker 2: forward and then the next thing happens, and the universe

537
00:26:19,080 --> 00:26:21,080
Speaker 2: ticks forward and the next thing happens. But you can

538
00:26:21,119 --> 00:26:23,439
Speaker 2: think of the whole universe as having like one clock,

539
00:26:23,720 --> 00:26:26,400
Speaker 2: so you can tell like one story about what happened

540
00:26:26,440 --> 00:26:29,840
Speaker 2: in the universe. Special relativity tells us that that's not

541
00:26:30,080 --> 00:26:33,800
Speaker 2: actually true, that there's lots of different clocks in the universe,

542
00:26:34,119 --> 00:26:37,560
Speaker 2: and how fast they tick depends on where you are

543
00:26:37,800 --> 00:26:40,240
Speaker 2: and how fast they're moving relative to you, So you

544
00:26:40,240 --> 00:26:43,000
Speaker 2: can actually tell lots of different stories about what happened

545
00:26:43,040 --> 00:26:46,720
Speaker 2: in the universe, even stories that conflict with each other,

546
00:26:46,920 --> 00:26:50,639
Speaker 2: that contradict each other about the order in which events happen.

547
00:26:51,040 --> 00:26:53,560
Speaker 1: Yeah, I know. We've talked about this before and include

548
00:26:53,600 --> 00:26:56,159
Speaker 1: it in our book. It's kind of this idea that

549
00:26:56,200 --> 00:26:59,080
Speaker 1: if two people run a race, you think that whoever

550
00:26:59,119 --> 00:27:01,399
Speaker 1: wins would be clear, but it sort of depends on

551
00:27:02,560 --> 00:27:06,200
Speaker 1: how fast they're moving and how fast the judges moving,

552
00:27:06,280 --> 00:27:08,280
Speaker 1: or how fast you're moving as an observer.

553
00:27:08,119 --> 00:27:11,040
Speaker 2: Right, Imagine two people running a race, but instead of

554
00:27:11,080 --> 00:27:13,760
Speaker 2: running alongside each other on a track the way people

555
00:27:13,760 --> 00:27:16,199
Speaker 2: typically do, imagine them starting in the same place but

556
00:27:16,280 --> 00:27:19,520
Speaker 2: running opposite directions. This makes it easier to think about

557
00:27:19,680 --> 00:27:22,040
Speaker 2: because they end up far apart from each other. If

558
00:27:22,080 --> 00:27:24,240
Speaker 2: you're standing at the starting line and you're not moving

559
00:27:24,720 --> 00:27:27,920
Speaker 2: relative to the starting line, imagine these two runners run

560
00:27:27,920 --> 00:27:30,320
Speaker 2: at the same speed relative to you. You call it

561
00:27:30,320 --> 00:27:32,240
Speaker 2: a tie. But if somebody else is flying along in

562
00:27:32,280 --> 00:27:35,119
Speaker 2: a spaceship alongside one of these runners, they see the

563
00:27:35,119 --> 00:27:38,359
Speaker 2: two runners moving at different speeds relative to them, and

564
00:27:38,520 --> 00:27:42,000
Speaker 2: moving clocks run slow, which means they see one of

565
00:27:42,040 --> 00:27:45,199
Speaker 2: these runners in slow motion relative to the other one,

566
00:27:45,359 --> 00:27:47,800
Speaker 2: So they'll think one of the runners wins the race

567
00:27:48,000 --> 00:27:50,760
Speaker 2: and the other one is slower. But another judge going

568
00:27:50,760 --> 00:27:53,399
Speaker 2: the opposite direction sees the same thing, but flipped. He

569
00:27:53,480 --> 00:27:56,680
Speaker 2: sees the first runner's clock running slow, so he thinks

570
00:27:56,680 --> 00:27:59,480
Speaker 2: the second runner wins the race. So who you think

571
00:27:59,520 --> 00:28:03,320
Speaker 2: wins the race depends on the speed you're going relative

572
00:28:03,400 --> 00:28:07,199
Speaker 2: to the runners. Like people can honestly disagree about the

573
00:28:07,320 --> 00:28:09,520
Speaker 2: order of events, did the first runner reach the finish

574
00:28:09,600 --> 00:28:12,000
Speaker 2: line first or did the second runner reach the finish

575
00:28:12,040 --> 00:28:14,359
Speaker 2: line first. This is not a case of like people

576
00:28:14,400 --> 00:28:18,560
Speaker 2: being confused or mistaken or getting things wrong. It means

577
00:28:18,560 --> 00:28:22,000
Speaker 2: that there are multiple true stories about what happened. In

578
00:28:22,040 --> 00:28:24,160
Speaker 2: the universe that conflict with each other.

579
00:28:24,680 --> 00:28:28,080
Speaker 1: Well, there's sort of one story, right, It's just when

580
00:28:28,119 --> 00:28:31,399
Speaker 1: you transform it between points of views, the order of

581
00:28:31,440 --> 00:28:32,240
Speaker 1: events changes.

582
00:28:32,359 --> 00:28:34,720
Speaker 2: Yeah. That sounds to me like multiple stories. But you're

583
00:28:34,800 --> 00:28:38,000
Speaker 2: right that we can link them together. Special relativity tells

584
00:28:38,080 --> 00:28:42,000
Speaker 2: us how to predict what any observer will see. And

585
00:28:42,040 --> 00:28:45,040
Speaker 2: what special relativity says is that different observers will see

586
00:28:45,080 --> 00:28:47,920
Speaker 2: the order in different events. The laws of physics are

587
00:28:47,960 --> 00:28:51,360
Speaker 2: consistent from frame to frame, and they predict the observers

588
00:28:51,360 --> 00:28:53,640
Speaker 2: tell different stories. Yeah, so you can think about that

589
00:28:53,680 --> 00:28:55,960
Speaker 2: as like one coherent understanding.

590
00:28:56,360 --> 00:28:59,160
Speaker 1: Yeah, that's what I mean. It's not like there's two realities.

591
00:28:59,360 --> 00:29:03,080
Speaker 1: Nobody can ever figure this out. It's more like, you know,

592
00:29:03,520 --> 00:29:06,840
Speaker 1: everyone has to agree on which observer they're measuring your

593
00:29:06,880 --> 00:29:07,280
Speaker 1: race by.

594
00:29:07,400 --> 00:29:09,160
Speaker 2: Right, that's right. It means that the order of events

595
00:29:09,200 --> 00:29:12,040
Speaker 2: is not universal, right, that it's dependent on the observer.

596
00:29:12,280 --> 00:29:14,400
Speaker 1: Well, or it is universal, as you said, it changes

597
00:29:14,520 --> 00:29:16,760
Speaker 1: depending on what you ask.

598
00:29:17,040 --> 00:29:19,120
Speaker 2: Yeah, it depends on the observer. Right, It's not something

599
00:29:19,160 --> 00:29:22,239
Speaker 2: everybody agrees on will happen from their point of view. Right,

600
00:29:22,240 --> 00:29:24,720
Speaker 2: Different points of view will see a different order of events,

601
00:29:25,120 --> 00:29:27,800
Speaker 2: and that's very confusing when you think about causality because

602
00:29:27,840 --> 00:29:30,480
Speaker 2: you think, like you know, there should be an order

603
00:29:30,520 --> 00:29:33,000
Speaker 2: two events, Like you can't finish the race before you

604
00:29:33,080 --> 00:29:36,400
Speaker 2: start it, you can't receive a message before you send it.

605
00:29:36,760 --> 00:29:39,080
Speaker 2: You can't die before you're born. There are some things

606
00:29:39,120 --> 00:29:43,000
Speaker 2: send in the universe where there's a causal link between them, right,

607
00:29:43,440 --> 00:29:45,560
Speaker 2: and so they have to happen in a certain order.

608
00:29:45,680 --> 00:29:48,719
Speaker 1: All right, Well, what does that mean for causality and antimatter?

609
00:29:48,760 --> 00:29:51,280
Speaker 2: Then well, you might think that this makes the universe nonsense,

610
00:29:51,680 --> 00:29:55,360
Speaker 2: because if different people can see events order different ways,

611
00:29:55,680 --> 00:29:57,680
Speaker 2: does not just break causality. Does that mean you can

612
00:29:57,720 --> 00:29:59,760
Speaker 2: eat an apple before it's grown? Does that mean you

613
00:29:59,800 --> 00:30:02,920
Speaker 2: can get a message before it's sent? This kind of stuff, Well,

614
00:30:02,920 --> 00:30:06,400
Speaker 2: special relativity has some protection built in for that, right,

615
00:30:06,440 --> 00:30:08,960
Speaker 2: It says this can only happen for things that are really,

616
00:30:09,000 --> 00:30:12,240
Speaker 2: really far apart, things that are so far apart that

617
00:30:12,360 --> 00:30:16,040
Speaker 2: light can't pass between them. We call these space like

618
00:30:16,080 --> 00:30:20,360
Speaker 2: events instead of timelike events. And so you can reorder

619
00:30:20,400 --> 00:30:23,240
Speaker 2: events that are really really far apart because they're already

620
00:30:23,320 --> 00:30:26,520
Speaker 2: not causally connected. If two things are so far apart

621
00:30:26,520 --> 00:30:29,400
Speaker 2: that light couldn't pass between them, then there's no way

622
00:30:29,480 --> 00:30:31,600
Speaker 2: for them to have a causal connection. You can't like

623
00:30:31,840 --> 00:30:34,720
Speaker 2: send a message from one to the other. And so

624
00:30:34,920 --> 00:30:39,280
Speaker 2: things that are already causally not connected. Those things you

625
00:30:39,320 --> 00:30:42,560
Speaker 2: can reorder by traveling at some crazy speed. Things that

626
00:30:42,600 --> 00:30:45,719
Speaker 2: are causally connected, Like if you turn on a flashlight

627
00:30:45,920 --> 00:30:48,840
Speaker 2: and then the beam arrive somewhere else, there's enough time

628
00:30:48,880 --> 00:30:50,920
Speaker 2: for light to get from one to the other. You

629
00:30:51,000 --> 00:30:54,240
Speaker 2: can't reorder those events just by going faster or.

630
00:30:54,200 --> 00:30:57,480
Speaker 1: Slower, all right, So then how does that figure into antimatter?

631
00:30:57,800 --> 00:31:00,520
Speaker 2: So these events that you can't reorder, those are things

632
00:31:00,520 --> 00:31:03,560
Speaker 2: we call inside our light cone. Light cone are things

633
00:31:03,560 --> 00:31:06,000
Speaker 2: that we can affect in our future, and there's things

634
00:31:06,040 --> 00:31:09,520
Speaker 2: that affected us from the past. So that special relativity,

635
00:31:09,560 --> 00:31:12,320
Speaker 2: and it has this nice causal connection for things inside

636
00:31:12,320 --> 00:31:14,760
Speaker 2: your light cone. Things outside your light cone, they can

637
00:31:14,800 --> 00:31:18,080
Speaker 2: get reordered by things going fast or slow. Quantum mechanics, however,

638
00:31:18,400 --> 00:31:22,840
Speaker 2: doesn't naturally obey this rule. Quantum mechanics has weird limitations

639
00:31:23,080 --> 00:31:27,239
Speaker 2: on how much you can know about objects momentums, and velocities. So,

640
00:31:27,280 --> 00:31:31,200
Speaker 2: for example, you measure a particle really really specifically. The

641
00:31:31,240 --> 00:31:35,120
Speaker 2: Heisenbergen certainty principle tells you you can't know anything about

642
00:31:35,200 --> 00:31:39,000
Speaker 2: its velocity, how fast it's going. So in principle, quantum

643
00:31:39,000 --> 00:31:42,800
Speaker 2: mechanics allows things to go faster than the speed of light.

644
00:31:43,080 --> 00:31:46,080
Speaker 2: That allows particles to move from one place to another

645
00:31:46,520 --> 00:31:49,680
Speaker 2: outside the light cone because they could be going faster

646
00:31:49,800 --> 00:31:52,640
Speaker 2: than the speed of light. Quantum mechanics doesn't have the

647
00:31:52,680 --> 00:31:55,960
Speaker 2: speed of light built into it naturally, it allows particles

648
00:31:56,040 --> 00:31:59,400
Speaker 2: to violate this speed limit. WHOA well.

649
00:32:01,520 --> 00:32:04,760
Speaker 1: On they think quantum mechanics can break the speed of light.

650
00:32:04,800 --> 00:32:06,920
Speaker 1: That sounds a little bit too much, Daniel. I think

651
00:32:06,960 --> 00:32:10,080
Speaker 1: you mean maybe, like our math allows it to, but

652
00:32:10,200 --> 00:32:12,560
Speaker 1: we don't know if in reality it can go faster

653
00:32:12,600 --> 00:32:13,760
Speaker 1: than light. Doing If you just.

654
00:32:13,760 --> 00:32:16,680
Speaker 2: Start from sort of low speed quantum mechanics, the original

655
00:32:16,720 --> 00:32:20,840
Speaker 2: quantum mechanics that was developed right, non relativistic quantum mechanics

656
00:32:20,840 --> 00:32:24,520
Speaker 2: for slow moving particles, then that theory with the Heisenberg

657
00:32:24,600 --> 00:32:28,040
Speaker 2: uncertainty principle doesn't respect the speed limit of the universe.

658
00:32:28,360 --> 00:32:30,360
Speaker 2: It's only when you try to bring quantum mechanics and

659
00:32:30,400 --> 00:32:34,160
Speaker 2: special relativity together to make a theory of relativistic high

660
00:32:34,160 --> 00:32:37,480
Speaker 2: speed particles that you have to answer this question like, uh, oh,

661
00:32:37,520 --> 00:32:40,800
Speaker 2: what happens if particles that quantum mechanics predicts can go

662
00:32:40,880 --> 00:32:43,040
Speaker 2: faster than the speed of light. What does special relativity

663
00:32:43,080 --> 00:32:45,360
Speaker 2: say about that? So it's you know, in trying to

664
00:32:45,480 --> 00:32:48,240
Speaker 2: bring the mathematics in harmony with the universe, that we

665
00:32:48,320 --> 00:32:50,240
Speaker 2: run into this problem. We're like, hold on a second.

666
00:32:50,600 --> 00:32:54,080
Speaker 2: Quantum mechanics has this problem with causality. It allows things

667
00:32:54,440 --> 00:32:58,960
Speaker 2: to move outside your light cone. What's going on and between?

668
00:32:59,000 --> 00:33:02,320
Speaker 2: You bring these two things together, that antiparticles save the

669
00:33:02,400 --> 00:33:05,479
Speaker 2: day and allow you to bring quantum mechanics and special

670
00:33:05,480 --> 00:33:07,920
Speaker 2: relativity together in a way that makes perfect sense.

671
00:33:08,880 --> 00:33:11,600
Speaker 1: I think maybe what you mean is that antimatter says

672
00:33:11,640 --> 00:33:17,000
Speaker 1: physicism because their original theory made no sense.

673
00:33:17,240 --> 00:33:20,040
Speaker 2: Yeah, you cannot bring quantum mechanics and special relativity together

674
00:33:20,160 --> 00:33:22,080
Speaker 2: without anti particles.

675
00:33:21,800 --> 00:33:24,760
Speaker 1: Right, It's like the limitations of the theory would allow

676
00:33:24,840 --> 00:33:28,400
Speaker 1: things to move faster than light, but probably in reality

677
00:33:28,440 --> 00:33:28,840
Speaker 1: they don't.

678
00:33:29,000 --> 00:33:30,880
Speaker 2: That's right. We think special relativity is the law of

679
00:33:30,920 --> 00:33:33,720
Speaker 2: the universe. Nothing moves faster than light. Original old school

680
00:33:33,760 --> 00:33:36,480
Speaker 2: quantum mechanics has this problem that allows things to move

681
00:33:36,520 --> 00:33:39,840
Speaker 2: faster than the speed of light, potentially breaking causality. And

682
00:33:39,840 --> 00:33:41,880
Speaker 2: you're right, we don't think that happens in reality, So

683
00:33:41,920 --> 00:33:44,480
Speaker 2: we need to patch up the theory, and it turns

684
00:33:44,480 --> 00:33:46,920
Speaker 2: out that we need antimatter in order to do that.

685
00:33:47,200 --> 00:33:50,760
Speaker 1: All right, well, let's dig into how antimatter saves the day.

686
00:33:51,000 --> 00:33:52,840
Speaker 1: It's sort of like a plot to is the villain

687
00:33:53,040 --> 00:33:54,920
Speaker 1: actually turns out to be the good guy. So let's

688
00:33:54,920 --> 00:33:57,160
Speaker 1: dig into that, and what does it mean about our

689
00:33:57,320 --> 00:34:00,239
Speaker 1: understanding of matter, antimatter and all kinds of matters or

690
00:34:00,320 --> 00:34:03,280
Speaker 1: in the universe. But first, let's take another quick break.

691
00:34:15,600 --> 00:34:18,640
Speaker 1: All right, we're talking about antimatter antiparticles. Why do we

692
00:34:18,680 --> 00:34:20,879
Speaker 1: have them? Why do we need them? It turns out

693
00:34:20,880 --> 00:34:26,520
Speaker 1: that they're useful in making our theories work, which is

694
00:34:26,560 --> 00:34:28,440
Speaker 1: not really I guess an answer to the question.

695
00:34:28,239 --> 00:34:28,480
Speaker 4: Is it?

696
00:34:28,520 --> 00:34:30,520
Speaker 2: Well, it's sort of an answer to the question. You know.

697
00:34:30,600 --> 00:34:34,000
Speaker 2: It says that the universe needs this to be consistent,

698
00:34:34,080 --> 00:34:36,560
Speaker 2: or our theories need this in order to be consistent

699
00:34:36,600 --> 00:34:38,160
Speaker 2: description of the universe.

700
00:34:38,320 --> 00:34:41,920
Speaker 1: Okay, so then you're saying that it somehow helps reconcile

701
00:34:41,960 --> 00:34:44,480
Speaker 1: special relativity and quantum mechanics. How does it do that?

702
00:34:44,560 --> 00:34:47,799
Speaker 2: So let's think about how quantum mechanics breaks causality. Right,

703
00:34:47,800 --> 00:34:50,799
Speaker 2: Imagine you have like a particle that you emit right

704
00:34:50,840 --> 00:34:53,759
Speaker 2: here at this moment, and quantum mechanics predicts that it

705
00:34:53,800 --> 00:34:57,040
Speaker 2: has a probability to end up like in Andromeda ten

706
00:34:57,120 --> 00:35:00,160
Speaker 2: seconds from now. That would break causality because if be

707
00:35:00,200 --> 00:35:02,360
Speaker 2: outside your leg cone, it would be like getting to

708
00:35:02,520 --> 00:35:05,680
Speaker 2: Andromeda faster than the speed of light. Nothing that we

709
00:35:05,760 --> 00:35:09,120
Speaker 2: do right now should be able to affect Andromeda until

710
00:35:09,120 --> 00:35:12,360
Speaker 2: millions of years into the future, because Andromeda is millions

711
00:35:12,440 --> 00:35:13,440
Speaker 2: of light years away.

712
00:35:13,600 --> 00:35:15,680
Speaker 1: I think you're saying, the quantum mechanics, we have a

713
00:35:15,680 --> 00:35:19,520
Speaker 1: description of a particle here, and because there's uncertainty about

714
00:35:19,520 --> 00:35:22,279
Speaker 1: where it can be, there's a certain probability that in

715
00:35:22,320 --> 00:35:25,600
Speaker 1: the next second it can be right where it is now,

716
00:35:25,719 --> 00:35:28,200
Speaker 1: or it can be a meter away or two meters away.

717
00:35:28,440 --> 00:35:31,120
Speaker 1: And there's a very very very small possibility that in

718
00:35:31,160 --> 00:35:34,799
Speaker 1: the next two seconds, according to the quantum mechanics, it

719
00:35:34,840 --> 00:35:37,800
Speaker 1: can then be in Andromeda. That's kind of how you

720
00:35:37,840 --> 00:35:38,520
Speaker 1: would describe it.

721
00:35:38,600 --> 00:35:41,319
Speaker 2: Yeah, exactly if you have a lot of uncertainty on

722
00:35:41,400 --> 00:35:44,720
Speaker 2: its momentum, because you've narrowed down its position super duper well,

723
00:35:45,080 --> 00:35:48,040
Speaker 2: and Heisenbergen certainty principle tells you can't know both things

724
00:35:48,080 --> 00:35:50,160
Speaker 2: at the same time. So if you know the position

725
00:35:50,239 --> 00:35:52,960
Speaker 2: really really well, you don't know the momentum, and therefore

726
00:35:53,000 --> 00:35:56,840
Speaker 2: there's a possibility that it has some crazy high momentum

727
00:35:56,840 --> 00:35:59,279
Speaker 2: would be faster than the speed of light, getting it

728
00:35:59,320 --> 00:36:03,000
Speaker 2: too Andrama in just ten seconds instead of the millions

729
00:36:03,040 --> 00:36:04,960
Speaker 2: of years it should take. And this would be a

730
00:36:05,000 --> 00:36:09,439
Speaker 2: problem for causality because those two events are spacelike. It's

731
00:36:09,480 --> 00:36:12,600
Speaker 2: outside of our light cone, which means that somebody flying

732
00:36:12,640 --> 00:36:14,600
Speaker 2: by in a spaceship could see them happen. In the

733
00:36:14,640 --> 00:36:18,200
Speaker 2: other order, could see this particle arrive in Andromeda before

734
00:36:18,239 --> 00:36:22,280
Speaker 2: it leaves our galaxy, which is nonsense. Right, So anything

735
00:36:22,320 --> 00:36:25,560
Speaker 2: that moves faster than the speed of light breaks causality.

736
00:36:25,560 --> 00:36:27,719
Speaker 2: That's one reason why we don't think things can move

737
00:36:27,760 --> 00:36:29,799
Speaker 2: faster than the speed of light, because it would allow

738
00:36:29,800 --> 00:36:33,279
Speaker 2: you to reorder events that are causally linked. Right, so

739
00:36:33,800 --> 00:36:35,320
Speaker 2: make the universe nonsense.

740
00:36:35,480 --> 00:36:37,760
Speaker 1: Well, it sort of sounds like quantum mechanics just breaks

741
00:36:37,760 --> 00:36:42,440
Speaker 1: causality anyways, right. Quantum mechanics say that particles can just

742
00:36:42,480 --> 00:36:46,080
Speaker 1: pop out of nowhere without any cause, So like quantum

743
00:36:46,080 --> 00:36:48,800
Speaker 1: mechanics says that a particle can suddenly disappear here and

744
00:36:48,840 --> 00:36:49,600
Speaker 1: appear in Andromeda.

745
00:36:50,200 --> 00:36:53,759
Speaker 2: Why not now, I wouldn't say that quantum mechanics necessarily

746
00:36:53,800 --> 00:36:56,840
Speaker 2: breaks causality. It makes a different description of the universe.

747
00:36:56,840 --> 00:37:00,560
Speaker 2: It makes the universe probabilistic instead of deterministic. It says

748
00:37:00,840 --> 00:37:03,279
Speaker 2: weird things can happen, like a photon can turn into

749
00:37:03,320 --> 00:37:06,320
Speaker 2: an electron and a positron, or it could do something else.

750
00:37:06,719 --> 00:37:09,240
Speaker 2: It says that the laws of the universe only predict

751
00:37:09,280 --> 00:37:12,520
Speaker 2: what might happen instead of what does actually happen. But

752
00:37:12,600 --> 00:37:15,160
Speaker 2: there is still causality, Like in quantum mechanics, the wave

753
00:37:15,160 --> 00:37:17,680
Speaker 2: function right now is determined by the wave function in

754
00:37:17,719 --> 00:37:21,240
Speaker 2: the past. Right The wave function itself doesn't specify exactly

755
00:37:21,320 --> 00:37:24,360
Speaker 2: what will happen, only to probabilities, but the wave function

756
00:37:24,440 --> 00:37:26,960
Speaker 2: is still determined by the past wave function, so there

757
00:37:26,960 --> 00:37:29,759
Speaker 2: should still be logic in quantum mechanics.

758
00:37:30,560 --> 00:37:32,560
Speaker 1: I guess that's weird because if you're saying that anything

759
00:37:32,680 --> 00:37:33,520
Speaker 1: might happen, I.

760
00:37:33,480 --> 00:37:36,400
Speaker 2: Would say anything might happen, you know quantum mechanics, as

761
00:37:36,560 --> 00:37:39,200
Speaker 2: is the probability for things to happen. Some things are

762
00:37:39,239 --> 00:37:43,320
Speaker 2: impossible even in quantum mechanics, like you can't violate conservation

763
00:37:43,400 --> 00:37:46,759
Speaker 2: of electric charge right, Electrons have no probability to turn

764
00:37:46,800 --> 00:37:51,040
Speaker 2: into positrons directly, because I would violate conservation of electric charge,

765
00:37:51,040 --> 00:37:53,760
Speaker 2: which is built into our quantum mechanical theories.

766
00:37:54,640 --> 00:37:57,719
Speaker 1: But haven't we talked about how like, according to quantum mechanics,

767
00:37:58,080 --> 00:38:01,600
Speaker 1: a pink elephant could certainly you're out of nowhere outside

768
00:38:01,640 --> 00:38:03,400
Speaker 1: of the Earth's orbit, right in space.

769
00:38:03,680 --> 00:38:06,320
Speaker 2: Yeah, that's not impossible. That doesn't break any of the rules.

770
00:38:06,360 --> 00:38:07,920
Speaker 1: But then we have no cause would it.

771
00:38:08,239 --> 00:38:10,600
Speaker 2: Well, the cause would be that there's a distribution of

772
00:38:10,640 --> 00:38:14,200
Speaker 2: probabilities for what those particles in the vacuum could do.

773
00:38:14,320 --> 00:38:16,640
Speaker 2: They could sit there and do nothing. They could create

774
00:38:16,680 --> 00:38:19,760
Speaker 2: one electron, they could create ten electrons, they could create

775
00:38:20,000 --> 00:38:23,240
Speaker 2: forty two trillion electrons. They could create a Boltzmann brain,

776
00:38:23,600 --> 00:38:26,760
Speaker 2: they could create a pink elephant. Those things are probabilities.

777
00:38:26,800 --> 00:38:29,960
Speaker 2: What does our universe choose one particular probability and not another?

778
00:38:30,280 --> 00:38:32,600
Speaker 2: What does it choose one that's like really unlikely, like

779
00:38:32,600 --> 00:38:35,359
Speaker 2: a pink elephant in space, and not another that's more

780
00:38:35,480 --> 00:38:38,280
Speaker 2: likely that we don't understand. That's like a deep question

781
00:38:38,520 --> 00:38:41,440
Speaker 2: in quantum philosophy, whether all of them happen at once

782
00:38:41,520 --> 00:38:45,040
Speaker 2: in different universes, whether the universe collapses these wave functions

783
00:38:45,040 --> 00:38:47,960
Speaker 2: to choose one. Whether it even is truly random, That

784
00:38:48,080 --> 00:38:50,279
Speaker 2: is definitely not something we know. But I wouldn't say

785
00:38:50,320 --> 00:38:53,480
Speaker 2: there's no cause there's still like a distribution of probabilities

786
00:38:53,480 --> 00:38:54,440
Speaker 2: for what might happen.

787
00:38:54,680 --> 00:38:57,520
Speaker 1: Well, let's get back to the antimatter particle. How does

788
00:38:57,520 --> 00:38:59,560
Speaker 1: that antimatter particle fit into this scenario.

789
00:38:59,600 --> 00:39:01,480
Speaker 2: Then it turns out if you do these calculations, and

790
00:39:01,480 --> 00:39:04,120
Speaker 2: you calculate like, okay, what's the probability for my particle

791
00:39:04,200 --> 00:39:06,080
Speaker 2: to appear in and Drama in ten seconds from now,

792
00:39:06,480 --> 00:39:11,080
Speaker 2: and you include antimatter, then those probabilities vanish. Because the

793
00:39:11,120 --> 00:39:14,160
Speaker 2: probability for you to see a particle go to Andrama

794
00:39:14,200 --> 00:39:18,040
Speaker 2: in ten seconds, there's another probability for a particle to

795
00:39:18,080 --> 00:39:21,840
Speaker 2: go from Andromeda to here in ten seconds, for an

796
00:39:21,880 --> 00:39:26,040
Speaker 2: antimatter particle to come the opposite direction. And because matter

797
00:39:26,120 --> 00:39:29,359
Speaker 2: and antimatter have all the opposite properties, those two things

798
00:39:29,480 --> 00:39:33,719
Speaker 2: quantum mechanically cancel each other out. So the antimatter nonsense

799
00:39:34,080 --> 00:39:39,040
Speaker 2: cancels out the matter nonsense to make no nonsense. Whoa, whoa, whoa.

800
00:39:39,120 --> 00:39:41,560
Speaker 1: Wait, we had this scenario of having one particle here

801
00:39:41,600 --> 00:39:44,879
Speaker 1: that suddenly appears in Andromeda in ten seconds. You're saying,

802
00:39:44,880 --> 00:39:49,080
Speaker 1: there's a different scenario in which an anti particle the

803
00:39:49,160 --> 00:39:54,080
Speaker 1: exact antiparticle of my particle is where my particle would appear.

804
00:39:54,880 --> 00:39:58,440
Speaker 1: That one disappears and appears where my current particle is

805
00:39:58,840 --> 00:40:01,680
Speaker 1: at the same time, and somehow that cancels it out.

806
00:40:01,840 --> 00:40:04,960
Speaker 1: But what are the chances that there's an antiparticle exactly

807
00:40:04,960 --> 00:40:07,040
Speaker 1: where my particle would go.

808
00:40:07,200 --> 00:40:09,680
Speaker 2: Well, all of this stuff is very unlikely. But when

809
00:40:09,719 --> 00:40:12,160
Speaker 2: you do a quantum mechanical calculation, you sum over all

810
00:40:12,239 --> 00:40:15,960
Speaker 2: the possibilities, and these equations are wave equations, so you

811
00:40:16,000 --> 00:40:19,719
Speaker 2: can get like constructive interference and destructive interference and things

812
00:40:19,760 --> 00:40:22,399
Speaker 2: where the probabilities cancel out, those things just don't happen.

813
00:40:22,560 --> 00:40:25,320
Speaker 2: Like in the Devil's Slight experiment. You see interference places

814
00:40:25,320 --> 00:40:28,520
Speaker 2: where lots of particles and places with no particles, the

815
00:40:28,520 --> 00:40:31,160
Speaker 2: places where no particles land, and the interference on the

816
00:40:31,200 --> 00:40:35,360
Speaker 2: screen is because there's been destructive interference among the probabilities.

817
00:40:35,640 --> 00:40:38,760
Speaker 2: So when the probabilities cancel out, those things just don't

818
00:40:38,760 --> 00:40:41,560
Speaker 2: happen in the universe, And so the probability for a

819
00:40:41,600 --> 00:40:45,400
Speaker 2: particle to break special relativity and appear in Andromeda is

820
00:40:45,440 --> 00:40:48,360
Speaker 2: canceled out by the probability for an antiparticle to do

821
00:40:48,440 --> 00:40:49,279
Speaker 2: the opposite.

822
00:40:49,360 --> 00:40:51,560
Speaker 1: Well, I guess what does it mean to cancel out

823
00:40:51,600 --> 00:40:53,720
Speaker 1: the probability? That means that it's never going to happen.

824
00:40:53,880 --> 00:40:56,319
Speaker 2: It means that it's never going to happen. And so

825
00:40:56,400 --> 00:41:00,200
Speaker 2: if you bring quantum mechanics and special relativity together, you

826
00:41:00,239 --> 00:41:04,040
Speaker 2: include anti particles, then it all clicks together perfectly and

827
00:41:04,080 --> 00:41:06,560
Speaker 2: you get no violations of causality.

828
00:41:06,800 --> 00:41:10,640
Speaker 1: But wait, the wouldn't that also cancel all movements like

829
00:41:10,680 --> 00:41:12,920
Speaker 1: even a meter distance?

830
00:41:13,080 --> 00:41:16,080
Speaker 2: Yeah, great question. It doesn't happen for things inside the

831
00:41:16,160 --> 00:41:19,400
Speaker 2: light cone because things inside the light cone everybody agrees

832
00:41:19,440 --> 00:41:22,160
Speaker 2: on the order, whereas things outside the light cone you

833
00:41:22,200 --> 00:41:25,359
Speaker 2: can reorder them. So, for example, if I say, well, look,

834
00:41:25,440 --> 00:41:28,160
Speaker 2: my particle left here and ended up in a drama

835
00:41:28,239 --> 00:41:31,600
Speaker 2: in ten seconds, that's outside my light cone. So somebody

836
00:41:31,640 --> 00:41:33,840
Speaker 2: else flying by in a spaceship might see them happen

837
00:41:33,920 --> 00:41:36,520
Speaker 2: in the opposite order. Right. Seeing it happen in the

838
00:41:36,520 --> 00:41:39,640
Speaker 2: opposite order is like seeing a particle go backwards in time,

839
00:41:39,920 --> 00:41:43,319
Speaker 2: which is equivalent to the anti matter particle. Right, So

840
00:41:43,880 --> 00:41:48,000
Speaker 2: both probabilities exist, the particle and anti particle version, because

841
00:41:48,040 --> 00:41:51,440
Speaker 2: you can reorder them because they are outside your light cone.

842
00:41:51,680 --> 00:41:54,879
Speaker 2: Things inside your light cone, you can't reorder them. Their

843
00:41:54,960 --> 00:41:57,680
Speaker 2: order is fixed. Only things outside the light cone where

844
00:41:57,719 --> 00:41:59,759
Speaker 2: you could reorder them, where somebody could see it as

845
00:41:59,760 --> 00:42:01,440
Speaker 2: a part article and the other person could see it

846
00:42:01,480 --> 00:42:04,440
Speaker 2: as an anti particle. Only those things cancel out.

847
00:42:04,640 --> 00:42:07,719
Speaker 1: It feels a little convenient, like maybe saying like, oh,

848
00:42:07,800 --> 00:42:10,719
Speaker 1: my theory breaks down after this limit. Let's just come

849
00:42:10,800 --> 00:42:13,759
Speaker 1: up with something totally different and ex sort it only

850
00:42:13,760 --> 00:42:16,240
Speaker 1: applies outside of this limit where my thing breaks.

851
00:42:16,480 --> 00:42:19,439
Speaker 2: Yeah. Well, it's sort of convenient and sort of spooky, right.

852
00:42:19,480 --> 00:42:22,000
Speaker 2: It's sort of like if you didn't know antiparticles existed

853
00:42:22,400 --> 00:42:24,800
Speaker 2: and you were trying to bring quantum mechanics and relativity

854
00:42:24,800 --> 00:42:28,440
Speaker 2: together into relativistic quantum mechanics, You're like, huh, this is

855
00:42:28,440 --> 00:42:31,520
Speaker 2: a problem. This could be solved if, for example, there

856
00:42:31,560 --> 00:42:34,560
Speaker 2: were the existence of antimatter hmm, and then you went

857
00:42:34,560 --> 00:42:36,360
Speaker 2: out in the universe and you found it, You'd be like, wow,

858
00:42:36,480 --> 00:42:38,400
Speaker 2: that was pretty cool. Here it's sort of works the

859
00:42:38,400 --> 00:42:41,839
Speaker 2: opposite direction. We're like, no antimatter exists, and we can

860
00:42:42,000 --> 00:42:44,640
Speaker 2: use it to help bring these two theories together. It

861
00:42:44,719 --> 00:42:47,200
Speaker 2: is very convenient, but that's sort of like a glorious

862
00:42:47,239 --> 00:42:49,920
Speaker 2: moment when you're like, oh wow, look these things. They

863
00:42:49,960 --> 00:42:52,080
Speaker 2: sort of need to exist for the universe to be

864
00:42:52,160 --> 00:42:52,960
Speaker 2: self consistent.

865
00:42:53,160 --> 00:42:55,280
Speaker 1: Now, you said something earlier that was kind of interesting.

866
00:42:55,320 --> 00:42:57,520
Speaker 1: You said, anti particles kind of go back in time.

867
00:42:57,560 --> 00:42:58,160
Speaker 1: What does that mean?

868
00:42:58,200 --> 00:43:00,920
Speaker 2: Well, mathematically you can look at it a particle moving

869
00:43:00,960 --> 00:43:04,480
Speaker 2: forwards in time, and it's equivalent to an antimatter particle

870
00:43:04,600 --> 00:43:06,919
Speaker 2: moving backwards in time. And you can sort of see

871
00:43:06,920 --> 00:43:09,799
Speaker 2: that in this example we're talking about, where like, my

872
00:43:09,920 --> 00:43:12,839
Speaker 2: particle goes from here to Andromeda, and it does it

873
00:43:12,920 --> 00:43:14,920
Speaker 2: faster than the speed of light. Right. If it does

874
00:43:14,960 --> 00:43:16,600
Speaker 2: it faster than the speed of light, that means that

875
00:43:16,719 --> 00:43:18,919
Speaker 2: somebody else going by in a spaceship they could see

876
00:43:18,920 --> 00:43:20,800
Speaker 2: it happen in the opposite order. They could see it

877
00:43:20,920 --> 00:43:25,319
Speaker 2: arrive in Andromeda before it leaves my house in the

878
00:43:25,320 --> 00:43:28,520
Speaker 2: milky way, right, which means that it's started in Andromeda.

879
00:43:28,640 --> 00:43:30,920
Speaker 2: The first event is in Andromeda. So I could say, look,

880
00:43:31,000 --> 00:43:33,560
Speaker 2: this is a particle going forwards in time faster than

881
00:43:33,600 --> 00:43:36,000
Speaker 2: the speed of light. Somebody else could say, no, it

882
00:43:36,000 --> 00:43:38,640
Speaker 2: goes the other direction. They could say, no, it's going

883
00:43:38,640 --> 00:43:41,360
Speaker 2: from your future to your past. But I see it

884
00:43:41,400 --> 00:43:44,800
Speaker 2: as an antimatter particle because they could reorder the events,

885
00:43:44,800 --> 00:43:47,719
Speaker 2: and so they see it going from Andromeda to the

886
00:43:47,760 --> 00:43:50,640
Speaker 2: Milky Way, and they see it moving as an antimatter particle.

887
00:43:50,840 --> 00:43:53,560
Speaker 1: But I guess maybe in order to measure my particle

888
00:43:53,640 --> 00:43:56,040
Speaker 1: here and there, don't I need to measure the particle,

889
00:43:56,160 --> 00:43:58,879
Speaker 1: wouldn't they collapse the wave function and make this all

890
00:43:59,000 --> 00:44:00,520
Speaker 1: kind of not really applicable.

891
00:44:00,560 --> 00:44:03,160
Speaker 2: You would need to collapse the wave function absolutely, and

892
00:44:03,239 --> 00:44:05,920
Speaker 2: of course it wouldn't really happen, right. That probability is

893
00:44:05,960 --> 00:44:08,200
Speaker 2: actually zero. You can't collapse the wave function and make

894
00:44:08,280 --> 00:44:10,680
Speaker 2: this happen. What we're talking about really is just a

895
00:44:10,719 --> 00:44:14,319
Speaker 2: partial probability. There's another part to that calculation, the antimatter part,

896
00:44:14,360 --> 00:44:17,399
Speaker 2: that cancels it out. So you can't actually do this right.

897
00:44:17,440 --> 00:44:21,320
Speaker 2: You can't see a particle appear in Andromeda in ten seconds.

898
00:44:21,320 --> 00:44:23,120
Speaker 2: It would take millions of years to get there, and

899
00:44:23,160 --> 00:44:25,440
Speaker 2: the probability for that to happen is canceled out by

900
00:44:25,440 --> 00:44:27,960
Speaker 2: the anti matter version, So that's why it just doesn't happen.

901
00:44:28,280 --> 00:44:30,920
Speaker 1: Is this sort of like one of those virtual particle

902
00:44:30,960 --> 00:44:33,560
Speaker 1: scenarios where like just a matter of fact that something

903
00:44:33,600 --> 00:44:38,440
Speaker 1: else can happen, actually in a way happens canceling out

904
00:44:38,719 --> 00:44:40,000
Speaker 1: other effects that are happening.

905
00:44:40,120 --> 00:44:42,160
Speaker 2: Yeah, you can think about this the way other quantum

906
00:44:42,160 --> 00:44:46,319
Speaker 2: mechanical weirdness happens, where like particles can interfere with themselves.

907
00:44:46,400 --> 00:44:48,880
Speaker 2: Right again, like in the double slit experiment, if you

908
00:44:48,920 --> 00:44:51,239
Speaker 2: don't know which slit the particle went through, has a

909
00:44:51,280 --> 00:44:54,320
Speaker 2: probability to go through both, and those probabilities can actually

910
00:44:54,320 --> 00:44:58,680
Speaker 2: interfere with themselves, So single particle interferes with itself. This

911
00:44:58,800 --> 00:45:01,160
Speaker 2: is sort of the same deal. Like this single particle

912
00:45:01,200 --> 00:45:03,680
Speaker 2: that goes from here to Andromeda, you could also be

913
00:45:03,760 --> 00:45:06,440
Speaker 2: seen as an antimatter particle going the other direction, and

914
00:45:06,440 --> 00:45:10,400
Speaker 2: those two probabilities cancel, which is why it never actually happens.

915
00:45:10,640 --> 00:45:12,839
Speaker 1: All right, Well, then what is the I guess main

916
00:45:12,880 --> 00:45:16,719
Speaker 1: takeaway is it that quantum mechanics does work with special activity,

917
00:45:16,800 --> 00:45:21,759
Speaker 1: and it's because antimatter particles exist or are a possibility

918
00:45:21,760 --> 00:45:22,400
Speaker 1: in the universe.

919
00:45:22,440 --> 00:45:26,680
Speaker 2: That's exactly right. You need antimatter to bring quantum mechanics

920
00:45:26,760 --> 00:45:30,799
Speaker 2: and special relativity together and not break causality. If we

921
00:45:30,880 --> 00:45:33,560
Speaker 2: think the universe is causal, meaning that like there's a

922
00:45:33,600 --> 00:45:36,840
Speaker 2: logical flow to things, that the past influences the future

923
00:45:37,200 --> 00:45:40,160
Speaker 2: and not the deep past. Then you need antimatter in

924
00:45:40,280 --> 00:45:43,520
Speaker 2: order to have special relativity and quantum mechanics. We just

925
00:45:43,560 --> 00:45:45,520
Speaker 2: don't know how to do it without antimatter.

926
00:45:45,719 --> 00:45:49,400
Speaker 1: Cool. All right, well, you've commissed me. I'm pro antimatter

927
00:45:50,239 --> 00:45:51,680
Speaker 1: or I'm not anti antimatter.

928
00:45:51,800 --> 00:45:54,080
Speaker 2: Does that mean that you're pro anti vanilla, which means

929
00:45:54,120 --> 00:45:55,320
Speaker 2: you're willing to try some chocolate.

930
00:45:55,360 --> 00:45:57,239
Speaker 1: I am pro anything with the word vanilla in it.

931
00:46:00,120 --> 00:46:02,960
Speaker 2: Right, I'm part of the vanilla eradication project. How do

932
00:46:02,960 --> 00:46:03,239
Speaker 2: you feel?

933
00:46:03,440 --> 00:46:08,960
Speaker 1: Oh my god? And that is how this podcast got canceled. Daniel.

934
00:46:10,280 --> 00:46:13,360
Speaker 1: Thank you, it's been a nice run. We're done.

935
00:46:13,480 --> 00:46:15,480
Speaker 2: No, I love vanilla. Vanilla is wonderful.

936
00:46:15,760 --> 00:46:18,480
Speaker 1: We've gone the way of Scott Adams and Dilbert.

937
00:46:19,400 --> 00:46:22,640
Speaker 2: I'm not a flavorist. Okay, I'm definitely pro vanilla.

938
00:46:22,680 --> 00:46:24,880
Speaker 1: I'm just more we think they're flavorists.

939
00:46:24,920 --> 00:46:29,800
Speaker 2: Daniel, I need to go for some flavor sensitivity training.

940
00:46:29,840 --> 00:46:34,399
Speaker 1: It sounds like, thank you, maybe you should examine those

941
00:46:34,440 --> 00:46:35,040
Speaker 1: anti FeAs.

942
00:46:37,120 --> 00:46:39,239
Speaker 2: All right, well, between this and the next episode, I

943
00:46:39,239 --> 00:46:43,040
Speaker 2: will do a deep dive into my own internal flavor preferences.

944
00:46:43,400 --> 00:46:47,640
Speaker 1: There you go examine your own anti matter. All right, Well,

945
00:46:47,800 --> 00:46:50,480
Speaker 1: another interesting bit of how we're trying to figure out

946
00:46:50,480 --> 00:46:53,520
Speaker 1: how the universe works, and how sometimes it's interesting how

947
00:46:53,760 --> 00:46:56,080
Speaker 1: our theories of the universe actually kind of turn out

948
00:46:56,080 --> 00:46:58,240
Speaker 1: to be true, which is kind of surprising, right.

949
00:46:58,360 --> 00:47:02,040
Speaker 2: It is surprising sometimes, and that crazy little human brains

950
00:47:02,080 --> 00:47:04,840
Speaker 2: can come up with mathematical stories that do seem to

951
00:47:04,920 --> 00:47:08,080
Speaker 2: describe the universe, even in ways we didn't anticipate.

952
00:47:08,400 --> 00:47:10,480
Speaker 1: All right, Well, thanks for joining us. We hope you

953
00:47:10,560 --> 00:47:12,040
Speaker 1: enjoyed that. See you next time.

954
00:47:14,480 --> 00:47:16,920
Speaker 2: Hey, everyone, I want to take a moment and share

955
00:47:17,000 --> 00:47:20,359
Speaker 2: a personal message with you. When I record these podcasts,

956
00:47:20,400 --> 00:47:22,759
Speaker 2: there's no live audience here, and so I have no

957
00:47:22,880 --> 00:47:25,920
Speaker 2: idea really how they're going to be received. So I

958
00:47:25,960 --> 00:47:28,680
Speaker 2: love hearing that they have an impact on people's lives,

959
00:47:28,719 --> 00:47:31,600
Speaker 2: maybe inspiring you to think about the universe, or talk

960
00:47:31,600 --> 00:47:34,239
Speaker 2: to your kids about physics, or even just keep your

961
00:47:34,280 --> 00:47:37,600
Speaker 2: brain going on long drive or a boring shift at work.

962
00:47:38,080 --> 00:47:40,799
Speaker 2: That's what gives me the energy to keep making these

963
00:47:40,920 --> 00:47:43,120
Speaker 2: to put them out twice a week without fail for

964
00:47:43,239 --> 00:47:46,080
Speaker 2: five years now. So it really heartens me to hear

965
00:47:46,080 --> 00:47:48,160
Speaker 2: from you. But I realize that you all don't get

966
00:47:48,160 --> 00:47:51,360
Speaker 2: to know each other as much to hear about these experiences.

967
00:47:51,560 --> 00:47:53,160
Speaker 2: So I want to share a little bit with you,

968
00:47:53,239 --> 00:47:56,000
Speaker 2: including an example that made me smile and one that

969
00:47:56,040 --> 00:47:59,239
Speaker 2: frankly brought some tears to my eyes. First, a happy one,

970
00:47:59,360 --> 00:48:02,040
Speaker 2: someone writes and says, I don't have a question but

971
00:48:02,120 --> 00:48:04,200
Speaker 2: a compliment. Just wanted to let both of you know

972
00:48:04,280 --> 00:48:06,840
Speaker 2: that I greatly appreciate the way you both explain physics.

973
00:48:07,040 --> 00:48:09,480
Speaker 2: As a person who has no science background and barely

974
00:48:09,520 --> 00:48:12,919
Speaker 2: passed college algebra, it's refreshing to hear people explain things

975
00:48:12,960 --> 00:48:16,120
Speaker 2: without talking down to the listener. That's wonderful and it's

976
00:48:16,160 --> 00:48:19,040
Speaker 2: exactly what we're trying to do, make physics more accessible

977
00:48:19,080 --> 00:48:22,080
Speaker 2: to everybody without dumbing it down at all. But some

978
00:48:22,120 --> 00:48:24,120
Speaker 2: of the messages we get are a little bit harder

979
00:48:24,160 --> 00:48:26,640
Speaker 2: to hear. A woman wrote in that her brother is

980
00:48:26,680 --> 00:48:29,839
Speaker 2: a listener and an ultrarunner, but that at thirty nine

981
00:48:30,120 --> 00:48:33,440
Speaker 2: he had a massive stroke and faces a long recovery.

982
00:48:33,920 --> 00:48:36,759
Speaker 2: She writes that quote each night he makes sure his

983
00:48:36,840 --> 00:48:39,800
Speaker 2: phone is charged and loaded with enough Daniel and Jorgey

984
00:48:39,840 --> 00:48:42,560
Speaker 2: to get him through the night. It's without drama that

985
00:48:42,640 --> 00:48:45,120
Speaker 2: I say that your show is one of his lifelines,

986
00:48:45,200 --> 00:48:49,040
Speaker 2: right now, you guys are his intellectual support above all,

987
00:48:49,120 --> 00:48:51,200
Speaker 2: on behalf of our family. I want to thank you

988
00:48:51,239 --> 00:48:53,839
Speaker 2: for your podcast and being a comfort to him in

989
00:48:53,920 --> 00:48:59,120
Speaker 2: this season. Wow, it's hard to overstate how deeply that

990
00:48:59,280 --> 00:49:02,400
Speaker 2: touches me, and I want to send him our encouragement

991
00:49:02,480 --> 00:49:05,120
Speaker 2: on his road to recovery. I'm so glad that we

992
00:49:05,160 --> 00:49:08,080
Speaker 2: can be there to help in this small way, and

993
00:49:08,120 --> 00:49:10,040
Speaker 2: I want to say thank you to everyone out there,

994
00:49:10,120 --> 00:49:12,399
Speaker 2: those of you who are listening and writing back or

995
00:49:12,520 --> 00:49:15,600
Speaker 2: just enjoying silently. You're all the reason that I do this.

996
00:49:23,600 --> 00:49:26,400
Speaker 2: Thanks for listening, and remember that Daniel and Jorge explain

997
00:49:26,440 --> 00:49:30,400
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts

998
00:49:30,480 --> 00:49:35,120
Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

999
00:49:35,200 --> 00:49:36,920
Speaker 2: you listen to your favorite shows.