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Why does the Universe have antiparticles? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Daniel, are you glad our universe has antimatter?
• 0:12
  Speaker 2: No, I'm definitely pro our universe. So I guess I'm
• 0:16
  Speaker 2: not anti antimatter.
• 0:18
  Speaker 1: That means your pro matter. But I guess the question is,
• 0:21
  Speaker 1: would you miss antimatter if we didn't have it?
• 0:24
  Speaker 2: I mean, I like things the way they are, so
• 0:26
  Speaker 2: if we lost antimatter, the universe would be pretty different
• 0:30
  Speaker 2: and maybe worse. But what if it's better, or maybe
• 0:33
  Speaker 2: it couldn't exist without antimatter and it would disappear in
• 0:36
  Speaker 2: a puff of mathematical contradictions.
• 0:38
  Speaker 1: Okay, then I would be anti antimatter. I would not
• 0:42
  Speaker 1: be pro antimatter.
• 0:43
  Speaker 2: I'm just saying it matters. Hi.
• 1:00
  Speaker 1: I'm Boria mccartoonist and the creator of PhD Comics.
• 1:03
  Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor
• 1:06
  Speaker 2: at UC Irvine, and I love all the kinds of
• 1:09
  Speaker 2: matter out there, the matter and the antimatter and the
• 1:11
  Speaker 2: pro matter.
• 1:12
  Speaker 1: What about the meh matter? Not pro, not anti, It's
• 1:17
  Speaker 1: it's just kind of there.
• 1:18
  Speaker 2: You know. I will admit that there are some particles
• 1:20
  Speaker 2: I think they're exciting. In other particles, I'm like, yeah,
• 1:22
  Speaker 2: that's just a mess.
• 1:23
  Speaker 1: About your favorite kind of matter is chocolate matters certainly
• 1:28
  Speaker 1: better than vanilla matter, karp matter, But anyways, welcome to
• 1:31
  Speaker 1: our podcast, Daniel and Jorge Explain the Universe, a production
• 1:34
  Speaker 1: of iHeartRadio.
• 1:35
  Speaker 2: In which we dig deep into all kinds of matter
• 1:38
  Speaker 2: out there that matters. We talk about the things that
• 1:40
  Speaker 2: make you up. We talk about the things that make
• 1:42
  Speaker 2: nothing up, and things that seem to exist for which
• 1:45
  Speaker 2: we do not yet understand. The whole universe is like
• 1:48
  Speaker 2: a jigsaw puzzle with lots of weirdly shaped pieces, and
• 1:51
  Speaker 2: our goal is to find all those pieces, fit them
• 1:53
  Speaker 2: together to tell the whole story of our universe. And
• 1:56
  Speaker 2: on this podcast we'd like to do that and try
• 1:58
  Speaker 2: to explain all of it to you.
• 2:00
  Speaker 1: That's right. It is a vast and complicated universe, full
• 2:03
  Speaker 1: of all kinds of crazy and interesting kinds of matter
• 2:07
  Speaker 1: and energy and concepts and mathematics that we like to
• 2:10
  Speaker 1: explore as human beings and ask questions about and then
• 2:12
  Speaker 1: explain it to you, or at least ask you the question,
• 2:15
  Speaker 1: what's the matter with you?
• 2:18
  Speaker 2: We study all of these particles, we try to understand them,
• 2:21
  Speaker 2: and sometimes we even taste them to see if they're delicious.
• 2:24
  Speaker 2: But I wasn't joking when I said that some of
• 2:26
  Speaker 2: the particles out there are a little crazier and harder
• 2:29
  Speaker 2: to think about than others. I mean, there are so
• 2:31
  Speaker 2: many particles discovered in the era of the particle Zoo
• 2:34
  Speaker 2: that we almost ran out of silly Greek letters to
• 2:37
  Speaker 2: use to name all of them.
• 2:38
  Speaker 1: Oh boy, what happens when you run out of Greek letters?
• 2:40
  Speaker 2: Then you start using Hebrew letters? Okay, like the Gimmel
• 2:44
  Speaker 2: particle on the aleph particle. H interesting, But we've discovered
• 2:48
  Speaker 2: so many weird masons and baryons that we had to
• 2:51
  Speaker 2: use some of those weird Greek letters that nobody even
• 2:53
  Speaker 2: really knows how to write down.
• 2:55
  Speaker 1: I guess we have done a pretty good job of
• 2:57
  Speaker 1: kind of looking out into the universe and basically talent
• 3:00
  Speaker 1: up all the different kinds of matter, all the different
• 3:02
  Speaker 1: kinds of particles that can't exist out there, because there
• 3:05
  Speaker 1: are a lot. As you're saying, there are.
• 3:06
  Speaker 2: A lot, and it's sort of a two step process
• 3:09
  Speaker 2: to understand the universe. Like number one, just look out
• 3:12
  Speaker 2: and see what's there. Gather together all the puzzle pieces.
• 3:15
  Speaker 2: Number two, try to click them together to tell the
• 3:18
  Speaker 2: whole story. Are there pieces missing, do they fit together
• 3:21
  Speaker 2: into a puzzle or is it just a weird, disjointed
• 3:24
  Speaker 2: pile of confusion.
• 3:25
  Speaker 1: Yeah, And I guess the history of it is that
• 3:27
  Speaker 1: we used to think that we knew what the building
• 3:29
  Speaker 1: blocks of the universe was, right. We thought the elements
• 3:32
  Speaker 1: of the periodic table were like the basic lego pieces
• 3:35
  Speaker 1: of the universe. But actually those turned to be made
• 3:38
  Speaker 1: of other things. And then those some of those things
• 3:40
  Speaker 1: turn to be made of other things.
• 3:42
  Speaker 2: That's right. We revealed this sort of hierarchical structure of matter,
• 3:45
  Speaker 2: things made of smaller things, made of smaller things, but
• 3:48
  Speaker 2: the path to understand them in the history of science
• 3:50
  Speaker 2: was not so straightforward. We sort of like drilled down
• 3:54
  Speaker 2: and then got wider and weirder, and then drilled down
• 3:56
  Speaker 2: again and got wider and weirder. For example, when we
• 3:59
  Speaker 2: wanted to understand the nucleus, when we wanted to understand
• 4:02
  Speaker 2: protons and neutrons and what's inside them, we'd build bigger
• 4:05
  Speaker 2: atom smashers and higher energy colliders, but we didn't immediately
• 4:09
  Speaker 2: find out what was inside the proton. Instead, first we
• 4:12
  Speaker 2: discovered all sorts of weird other kinds of particles that
• 4:15
  Speaker 2: don't exist inside the atom, chaons and pions and rope
• 4:18
  Speaker 2: particles and omega particles and all sorts of other Greek letters.
• 4:21
  Speaker 2: I don't even know how to pronounce. Things got weird
• 4:24
  Speaker 2: before they got clearer.
• 4:26
  Speaker 1: Yeah, no, I understand. It's all Greek to me.
• 4:30
  Speaker 2: In the same way that we want to understand what's
• 4:32
  Speaker 2: inside the quarks that make up the proton, but first
• 4:35
  Speaker 2: we found more quarks along the way. Instead of figuring
• 4:38
  Speaker 2: out what's inside the upcork and the down cork, we
• 4:40
  Speaker 2: found the charm and the strange, and the top and
• 4:42
  Speaker 2: the bottom. So the universe gives us a big pile
• 4:45
  Speaker 2: of clues before it reveals its deepest secrets.
• 4:48
  Speaker 1: Yeah, it is a weird universe full of surprises. And
• 4:51
  Speaker 1: one of the weirdest things about matter in the universe
• 4:54
  Speaker 1: is that it seems to have an opposite to it.
• 4:57
  Speaker 1: There seems to be a lot of antimatter in the universe.
• 5:00
  Speaker 2: Every particle out there seems to have its weird twin.
• 5:02
  Speaker 2: And we don't know if this is a detour in
• 5:04
  Speaker 2: our path to finally understanding what is the fundamental nature
• 5:08
  Speaker 2: of matter, or if it's a crucial side quest to
• 5:11
  Speaker 2: get a clue that will help us unlock the deepest mystery.
• 5:15
  Speaker 2: We don't know if and of matter is necessary, we
• 5:17
  Speaker 2: don't know what role it plays, We don't really know
• 5:20
  Speaker 2: what clue it's giving us about the nature of the universe.
• 5:23
  Speaker 1: And so to the other podcast, we'll be asking the
• 5:26
  Speaker 1: question why do we have anti particles? Feel like that's
• 5:34
  Speaker 1: a weird double negative question, like why don't we have particles?
• 5:40
  Speaker 1: Or why do we have anti particles? What's the correct
• 5:43
  Speaker 1: grammar here or is it in Greek?
• 5:46
  Speaker 2: I think why do we have anti particles? Is the
• 5:48
  Speaker 2: deep question? You know, every time we see something in
• 5:50
  Speaker 2: the universe, we wonder like, hmmm, did it have to
• 5:53
  Speaker 2: be this way? Is this necessary? Is this a clue
• 5:56
  Speaker 2: as to the fundamental nature of the universe or just
• 5:59
  Speaker 2: sort of like a random accident.
• 6:00
  Speaker 1: Well, so, as usual, we were wondering how many people
• 6:02
  Speaker 1: out there had thought about this question or have any
• 6:05
  Speaker 1: ideas about why we have anti particles.
• 6:08
  Speaker 2: So thank you very much to everybody who answers these
• 6:10
  Speaker 2: questions for this fun segment of our podcast. If you
• 6:13
  Speaker 2: would like to play along next time, please don't be shy.
• 6:16
  Speaker 2: Write to me two questions at Danielandjorge dot Com.
• 6:20
  Speaker 1: So think about it for a second. Why do you
• 6:21
  Speaker 1: think we have anti particles? Here's what people had to say.
• 6:25
  Speaker 3: In general, antiparticles exist because particles exist and there's some
• 6:30
  Speaker 3: sort of balance that was broken at.
• 6:33
  Speaker 1: The Big Bang.
• 6:34
  Speaker 4: I don't know, but the universe seems to like symmetry,
• 6:38
  Speaker 4: and somehow antiparticles had to exist for some kind of
• 6:45
  Speaker 4: symmetry to be to be fulfilled. But I don't know.
• 6:50
  Speaker 4: It's kind of crazy.
• 6:51
  Speaker 1: I think anti particles exist for the same reason you
• 6:54
  Speaker 1: don't get monopole magnets.
• 6:56
  Speaker 2: But I'm got clear, so we'll say with me, well
• 6:58
  Speaker 2: maybe not.
• 6:59
  Speaker 3: I feel like you need the antiparticles like cancel it out,
• 7:02
  Speaker 3: because you can't have like something from nothing. You need
• 7:06
  Speaker 3: to have something and then the opposite of it, so
• 7:10
  Speaker 3: that like overall nothing has changed.
• 7:13
  Speaker 5: Any particles are probably like the ying and yang. For
• 7:17
  Speaker 5: every particle, there has to exist an anti particle in
• 7:20
  Speaker 5: order to balance the forces in the universe, similar to
• 7:25
  Speaker 5: matter and anti matter.
• 7:27
  Speaker 6: I think the reason why antiparticles exist is because everything
• 7:31
  Speaker 6: in nature and physics seems to be balanced. So if
• 7:34
  Speaker 6: you sum up everything, it comes off like zero. But yeah,
• 7:38
  Speaker 6: for everything that exists, there needs to be an anti
• 7:40
  Speaker 6: thing Somemari like Ying and Young.
• 7:42
  Speaker 1: All right, some very philosophical answers here, some of them
• 7:46
  Speaker 1: kind of zen.
• 7:47
  Speaker 2: Yeah, there's a lot of philosophy in these questions, you know,
• 7:50
  Speaker 2: wondering whether the universe could have multiple explanations or just
• 7:53
  Speaker 2: one explanation, or whether it has any explanation at all,
• 7:57
  Speaker 2: whether it makes sense, and whether it's sensible to human minds.
• 8:00
  Speaker 2: All that stuff is tied up in this quest to
• 8:03
  Speaker 2: understand the universe.
• 8:04
  Speaker 1: Do you think maybe there are anti particle scientists out
• 8:07
  Speaker 1: there and or cartoonists we're wondering why do we have particles?
• 8:11
  Speaker 1: What is this weird stuff?
• 8:12
  Speaker 2: I don't know, but humans are capable of developing science
• 8:15
  Speaker 2: as well as antiscience. More recently, I'm.
• 8:18
  Speaker 1: Just antiphysics, I like all the other sciences.
• 8:21
  Speaker 2: Are you antiphysics or are you anti physicists?
• 8:23
  Speaker 1: I'm anti answering that question and that's an answer to
• 8:27
  Speaker 1: that a position there. Well, let's dig into it, Daniel Water,
• 8:33
  Speaker 1: anti particles is it like antimatter exactly?
• 8:35
  Speaker 2: Anti particles are what make up anti matter. So matter
• 8:39
  Speaker 2: is the stuff that we find around us that you
• 8:41
  Speaker 2: were made of. That I am made out of everything
• 8:43
  Speaker 2: you have ever eaten is made out of particles that
• 8:46
  Speaker 2: we call matter particles. So you and I are made
• 8:49
  Speaker 2: out of protons, neutrons, and electrons, and those protons and
• 8:53
  Speaker 2: neutrons are made up of quarks. Anti matter is made
• 8:57
  Speaker 2: up of anti particles, so you could have, for example,
• 9:00
  Speaker 2: anti hydrogen is made of an anti proton and an
• 9:04
  Speaker 2: anti electron, where the anti proton is then made of
• 9:07
  Speaker 2: anti quarks. So there's a close connection, of course between
• 9:10
  Speaker 2: anti matter and anti particles.
• 9:12
  Speaker 1: I see. So particles are the little things that we're
• 9:16
  Speaker 1: all made out of, and some of them have anti
• 9:19
  Speaker 1: versions of them. Do all particles have anti versions or
• 9:22
  Speaker 1: only some of them? Like do the force particles have
• 9:24
  Speaker 1: anti force particles?
• 9:26
  Speaker 2: Great question, sort of yes and no. All the particles
• 9:29
  Speaker 2: have anti particles, but some of them are their own
• 9:33
  Speaker 2: anti particles, so I'm not sure if that counts as
• 9:36
  Speaker 2: having an anti particle. So, for example, the electron has
• 9:39
  Speaker 2: an antiparticle the positron, and the muon has an anti
• 9:43
  Speaker 2: particle the anti muon, and the quarks have antiparticles the
• 9:47
  Speaker 2: anti quarks. Those are different particles, or you could think
• 9:50
  Speaker 2: of them as two parts of the same pair. But
• 9:52
  Speaker 2: they are distinct states. But then particles, like you said,
• 9:55
  Speaker 2: the force carrying particles like the photon, the photon is
• 9:59
  Speaker 2: its own anti particle, and so you might also say
• 10:02
  Speaker 2: it doesn't have an anti particle. But I'd like to
• 10:04
  Speaker 2: think about it as one particle playing two roles.
• 10:07
  Speaker 1: What about some of the other force particles, do they
• 10:09
  Speaker 1: have anti versions?
• 10:10
  Speaker 2: Well, there are two w bosons, and they are each
• 10:13
  Speaker 2: other's antiparticles. So you have the W plus and the
• 10:15
  Speaker 2: W minus for example. So those two force particles are
• 10:19
  Speaker 2: each other's anti particles, which is why we have two
• 10:21
  Speaker 2: of them. The Z boson is its own antiparticle, and
• 10:25
  Speaker 2: the gluon is actually eight gluons, all of different colors,
• 10:29
  Speaker 2: and some of them are each other's antiparticles. So you
• 10:31
  Speaker 2: can have like a red anti green gluon, which is
• 10:35
  Speaker 2: the antiparticle to the anti red green gluon. It gets
• 10:38
  Speaker 2: really colorful with gluons.
• 10:41
  Speaker 1: Well, I feel bad for those particles that are their
• 10:43
  Speaker 1: own anti versions of themselves. It's like they're their own
• 10:45
  Speaker 1: worst enemies.
• 10:47
  Speaker 2: Or maybe they're lonely. Right, one is the loneliest number.
• 10:50
  Speaker 1: After all, this should hang out together.
• 10:53
  Speaker 2: Some people confuse anti matter with dark matter, And there's
• 10:57
  Speaker 2: lots of mysteries in particle physics, right, lots of things
• 11:00
  Speaker 2: that we don't understand about the universe, But those are
• 11:03
  Speaker 2: two separate mysteries. Dark matter is the invisible matter that's
• 11:07
  Speaker 2: out there in the universe that we know is holding
• 11:09
  Speaker 2: galaxies together and shaping the whole development of the large
• 11:13
  Speaker 2: scale structure of the universe. We don't know what it is,
• 11:15
  Speaker 2: and if it's made of particles, that's a different idea
• 11:18
  Speaker 2: from antimatter. Antimatter is a real thing that we can make,
• 11:22
  Speaker 2: that we can study. We've seen it in our detectors.
• 11:24
  Speaker 2: We know for sure that it exists and it's made
• 11:27
  Speaker 2: of anti particles.
• 11:29
  Speaker 1: Well, I guess maybe the question now is how do
• 11:31
  Speaker 1: you make antimatter? Can you make it or does it
• 11:34
  Speaker 1: exist in nature or is it just a matter of
• 11:36
  Speaker 1: like flipping the sign on some quantum property of regular particles.
• 11:40
  Speaker 2: So sort of all of the above. Antimatter isn't very common.
• 11:43
  Speaker 2: The universe is almost entirely made of matter, meaning it's
• 11:47
  Speaker 2: made of particles instead of anti particles, but sometimes antimatter
• 11:51
  Speaker 2: is produced, though it doesn't last very long because it
• 11:54
  Speaker 2: runs into normal particles and annihilates but for example, the
• 11:58
  Speaker 2: discovery of anti I mapps, which led to the nineteen
• 12:01
  Speaker 2: thirty three Nobel Prize, was from naturally produced antimatter. So
• 12:07
  Speaker 2: a positron the opposite particle to an electron produced in
• 12:11
  Speaker 2: cosmic rays, meaning high energy collisions of particles from space
• 12:15
  Speaker 2: hitting the upper atmosphere and creating antimatter which then showered
• 12:19
  Speaker 2: down to the surface of the Earth.
• 12:21
  Speaker 1: So when was this When was the first time we
• 12:23
  Speaker 1: saw antimatter?
• 12:24
  Speaker 2: So it was first observed in the late nineteen twenties.
• 12:27
  Speaker 2: It was predicted by Paul Durack, the quantum physicist, who
• 12:30
  Speaker 2: saw the mathematical need for them in his equations, and
• 12:33
  Speaker 2: he said, hm, my equations predict there should be electrons
• 12:36
  Speaker 2: and should also be another particle with the opposite charge
• 12:39
  Speaker 2: as the electron. So he predicted it, and then Carl
• 12:41
  Speaker 2: Anderson saw it. We have a whole fun podcast episode
• 12:44
  Speaker 2: about the discovery of antimatter and the twists and turns
• 12:47
  Speaker 2: and the egos involved. It's a really fun story. Check
• 12:50
  Speaker 2: that out. We've known about it for almost one hundred
• 12:52
  Speaker 2: years now.
• 12:53
  Speaker 1: It sort of involves cloud chambers, right, which is something
• 12:56
  Speaker 1: you can usually find in most science museums.
• 12:58
  Speaker 2: Yeah, early particle physics didn't have fancy digital electronics and
• 13:02
  Speaker 2: the complicated detectors we have now. They had to use
• 13:05
  Speaker 2: techniques to observe the paths of these particles with the
• 13:09
  Speaker 2: technology they had. And one thing you can do to
• 13:11
  Speaker 2: illuminate what particles are flying through the air around you
• 13:15
  Speaker 2: is to create clouds of water vapor. If you have
• 13:18
  Speaker 2: air that's super saturated with water, meaning it actually has
• 13:21
  Speaker 2: more water in it than it likes to have, then
• 13:24
  Speaker 2: it's very easy to knock that water out of the air,
• 13:27
  Speaker 2: and a passing charge particle will do just that and
• 13:30
  Speaker 2: will create a string of droplets in the air. You
• 13:33
  Speaker 2: can actually create cloud chambers at home. Check out lots
• 13:35
  Speaker 2: of YouTube videos for how to do this. You can
• 13:37
  Speaker 2: build one in your garage. You can see them at
• 13:39
  Speaker 2: science museums and so you can see high energy particles
• 13:43
  Speaker 2: streaming through the air around you, muons and all sorts
• 13:45
  Speaker 2: of stuff. Carl Anderson proved that a fraction of these
• 13:48
  Speaker 2: are actually anti matter particles, and he did that by
• 13:51
  Speaker 2: showing how they curve differently in magnetic fields. Because magnetic
• 13:54
  Speaker 2: fields will change the path of a charge particle depending
• 13:57
  Speaker 2: on the charge. A positive charge will be in it
• 14:00
  Speaker 2: one way. A negative charge will bend it the other way.
• 14:03
  Speaker 2: So he saw particles that had the same mass as electrons,
• 14:06
  Speaker 2: but bend in the other.
• 14:07
  Speaker 1: Direction like a positively charged electron. Is that basically what
• 14:13
  Speaker 1: an anti electron is, Just an electron with a charge flip.
• 14:16
  Speaker 2: Yeah, that's what antiparticles are. They're just like their particle counterparts,
• 14:20
  Speaker 2: but they have the opposite charges, so the opposite electric charge,
• 14:24
  Speaker 2: the opposite weak charges, and the opposite color charges. So
• 14:27
  Speaker 2: in the case of the electron, it's basically a positively
• 14:30
  Speaker 2: charged electron.
• 14:31
  Speaker 1: Right, because I guess an electron doesn't have the weak
• 14:34
  Speaker 1: charge and it doesn't have the strong charge.
• 14:36
  Speaker 2: Right, Electrons do have the weak charge. Actually, remember, the
• 14:39
  Speaker 2: weak force is actually unified with electromagnetism into one force
• 14:43
  Speaker 2: we call electro week, and electrons can interact via the
• 14:46
  Speaker 2: weak force. They can emit w's for example, that's how
• 14:49
  Speaker 2: beta decay happens. So electrons interact with the weak force.
• 14:52
  Speaker 2: In fact, every particle we've ever seen interacts with a
• 14:55
  Speaker 2: weak force, which is fascinating because the other forces are
• 14:58
  Speaker 2: not so democratic. The strong force only interacts with quarks
• 15:02
  Speaker 2: and not at all with electrons or neutrinos, and electromagnetism
• 15:06
  Speaker 2: doesn't interact with neutrinos. But we've never found a particle
• 15:09
  Speaker 2: that doesn't have any kind of weak charge. Every particle
• 15:12
  Speaker 2: out there so far we discovered interacts with the weak force.
• 15:15
  Speaker 1: Wait, what's the name of the week charge? If you
• 15:17
  Speaker 1: have a week charge, what is that called?
• 15:19
  Speaker 2: Well, there's actually two different week charges. One of them
• 15:22
  Speaker 2: is called weak isospin and the other one is called
• 15:24
  Speaker 2: weak hypercharge. But you can combine them actually to make
• 15:27
  Speaker 2: electromagnetic charge. So there's two different charges for the electro
• 15:31
  Speaker 2: weak force, but one of them is really from electromagnetism.
• 15:34
  Speaker 1: I'll pretend I totally understood that. But I guess when
• 15:38
  Speaker 1: you're trying to make an anti electron, which one do
• 15:40
  Speaker 1: you flip? Do you flip the electromagnetic charge like the
• 15:43
  Speaker 1: you know, plus and minds that we're all familiar with,
• 15:45
  Speaker 1: or do you flip one of these other sub charges?
• 15:47
  Speaker 1: And if you do, do I mean there are several
• 15:49
  Speaker 1: versions of an anti electron.
• 15:51
  Speaker 2: Now you flip all the charges. So there's only one
• 15:53
  Speaker 2: version of a positron, and it has a positive electric charge.
• 15:56
  Speaker 2: It also has both of its weak charges flipped.
• 15:58
  Speaker 1: But what if you flip one and the other you
• 16:00
  Speaker 1: can't do that, man, don't do that. They'll tell you
• 16:02
  Speaker 1: why not to do, tell you why I can't do it.
• 16:05
  Speaker 1: Then I can choose whether or not I can't.
• 16:07
  Speaker 2: I will do it. It's not me, man, it's the
• 16:10
  Speaker 2: laws of the universe. No, we do not see particles
• 16:13
  Speaker 2: where only one charge is flipped and the other one
• 16:16
  Speaker 2: is not.
• 16:16
  Speaker 1: Why not.
• 16:17
  Speaker 2: Yeah, that's a very cool question, imagining particles that are
• 16:20
  Speaker 2: particles according to one force and anti particles according to
• 16:24
  Speaker 2: another force. Remember, we recently answered a question about whether
• 16:27
  Speaker 2: it even matters whether you're calling something matter or antimatter,
• 16:31
  Speaker 2: and turns out that's totally an arbitrary distinction. So it
• 16:34
  Speaker 2: doesn't really matter if one force considers a particle matter
• 16:37
  Speaker 2: and the other one considers a particle the anti matter.
• 16:40
  Speaker 2: But the forces do have to be consistent, and in
• 16:42
  Speaker 2: the case of the weak force and electromagnetism, for example,
• 16:46
  Speaker 2: they are tightly linked, so you can't just flip one
• 16:49
  Speaker 2: and not the other. The charges of the two forces
• 16:51
  Speaker 2: really are connected by the structure of the theory.
• 16:54
  Speaker 1: I think what you're what you're saying, is this matter
• 16:57
  Speaker 1: anti matter distinction is really kind of arbitrary kind of right,
• 17:01
  Speaker 1: Like it's not as clear cut, like maybe there are
• 17:03
  Speaker 1: shades of gray or shades of antiness.
• 17:06
  Speaker 2: Yeah, we definitely don't claim to understand everything there is
• 17:08
  Speaker 2: to know about antimatter. But I think you're right A
• 17:11
  Speaker 2: lot of this comes down to just like what do
• 17:12
  Speaker 2: you call matter and what do you call antimatter. A
• 17:15
  Speaker 2: crucial idea is that there are these symmetries that you
• 17:17
  Speaker 2: can flip these charges and the equations still work, that
• 17:21
  Speaker 2: the universe can do both of these things, and so
• 17:24
  Speaker 2: it does in some cases. We have like multiple ways
• 17:27
  Speaker 2: to categorize what is matter and what is antimatter.
• 17:30
  Speaker 1: Well, I think the thing that most people probably remember
• 17:32
  Speaker 1: about antimatter, and that maybe is relevant here, is that
• 17:36
  Speaker 1: like a matter particle and it's antimatter particle, if they touch,
• 17:39
  Speaker 1: then they annihilate. They become pure energy. Right, We've talked
• 17:43
  Speaker 1: about that before they explode. That's one of the things
• 17:45
  Speaker 1: about antimatter.
• 17:47
  Speaker 2: Particles and their antiparticles can annihilate into a force particle.
• 17:51
  Speaker 2: So for example, an electron and a positron can come
• 17:54
  Speaker 2: together to make a photon or a z boson and
• 17:57
  Speaker 2: a and an anti quark can come together to make
• 18:00
  Speaker 2: a glue on, and the opposite can happen. Also, a
• 18:03
  Speaker 2: photon can turn into a matter antimatter pair, or a
• 18:06
  Speaker 2: z boson can decay into a muon and its anti particle.
• 18:11
  Speaker 1: But then I guess if anti nus is kind of
• 18:13
  Speaker 1: relative or there's a gray area there, or how does
• 18:16
  Speaker 1: that affect the annihilation? Like if I take a cork
• 18:19
  Speaker 1: and an antiquark, but I flip some other other signs,
• 18:22
  Speaker 1: do they still annihilate?
• 18:23
  Speaker 2: They can annihilate if there is a particle that carries
• 18:26
  Speaker 2: their combined charges. So for example, an electron and a
• 18:30
  Speaker 2: positron can annihilate because in total they have zero electric
• 18:33
  Speaker 2: charge and the photon has zero electric charge. That's why
• 18:37
  Speaker 2: an electron cannot annihilate with another electron, because then you'd
• 18:40
  Speaker 2: have to have a particle with a minus two charge
• 18:42
  Speaker 2: in order to conserve electric charge. So the same thing
• 18:46
  Speaker 2: goes for the other charges.
• 18:47
  Speaker 1: So like if I have a green cork and an
• 18:49
  Speaker 1: anti green cork, but a given different you know, regular charges,
• 18:54
  Speaker 1: what's gonna happen? Are they going to annihilate or repel
• 18:56
  Speaker 1: each other? Or what I'm just trying to get at,
• 18:58
  Speaker 1: Like what it means to be anti mime. Is it
• 19:00
  Speaker 1: depending on this annihilation thing or is it kind of random.
• 19:03
  Speaker 2: It's a little bit more complicated for the color charge
• 19:05
  Speaker 2: because gluons themselves are colored. You know, the photons don't
• 19:09
  Speaker 2: have any charge for example, right, so it's simple plus
• 19:12
  Speaker 2: and minus annihilate to zero charge photons. In the case
• 19:15
  Speaker 2: of gluons, gluons do carry color. In fact, they carry
• 19:18
  Speaker 2: two colors, which is even more confusing. So for example,
• 19:21
  Speaker 2: a red anti green quark can combine to make red
• 19:25
  Speaker 2: anti green gluon. The glue on itself carries two of
• 19:28
  Speaker 2: those colors, but the gluons don't carry electric charge, so
• 19:32
  Speaker 2: this can only happen for quarks that have opposite electric
• 19:35
  Speaker 2: charges that can balance out to zero electric charge. So
• 19:39
  Speaker 2: one way to think about how to pair particles and
• 19:41
  Speaker 2: antiparticles is whether they can annihilate into these force particles.
• 19:46
  Speaker 1: I see, So maybe one particle can have multiple anti
• 19:49
  Speaker 1: versions of itself.
• 19:50
  Speaker 2: There are definitely multiple different versions of quarks that an
• 19:53
  Speaker 2: individual quark can annihilate with to create a gluon. Because
• 19:57
  Speaker 2: there are so many different kinds of gluons, they always
• 20:00
  Speaker 2: have to have opposite electric charges. Because the gluons don't
• 20:03
  Speaker 2: have electric charge, So yeah, it gets really complicated when
• 20:06
  Speaker 2: you're talking about the color charges because there's multiple different
• 20:10
  Speaker 2: color charges and the gluons carry them themselves, and so
• 20:12
  Speaker 2: the whole thing is a big mess.
• 20:14
  Speaker 1: Is that how you end every physics paper? YadA YadA,
• 20:17
  Speaker 1: YadA YadA, And it's all a big mess.
• 20:19
  Speaker 2: It's a big mess, and it's a glorious puzzle and
• 20:21
  Speaker 2: we're still working to try to figure it out. Yeah.
• 20:24
  Speaker 1: Cool, Well, I guess the big question is still why
• 20:27
  Speaker 1: do we have anti particles at all? Why do they
• 20:30
  Speaker 1: exist in the universe? And so let's dig into that
• 20:33
  Speaker 1: question and some of the other open questions about antimatter.
• 20:38
  Speaker 1: But first let's take a quick break. All right, we're
• 20:52
  Speaker 1: talking about antimatter antiparticles and why do we need them
• 20:56
  Speaker 1: at all? Which sounds like a very insensitive question.
• 21:00
  Speaker 2: What the deepest question we ask when we see something
• 21:02
  Speaker 2: in the universe, We ask like, why is it this
• 21:04
  Speaker 2: way and not some other way? Does it have to
• 21:06
  Speaker 2: be this way? Is the universe parsimonious, like it only
• 21:10
  Speaker 2: contains things that have to happen? Or is it sort
• 21:12
  Speaker 2: of like baroque that has all sorts of flourishes that
• 21:14
  Speaker 2: it doesn't really need, and it's just sort of beautiful.
• 21:16
  Speaker 2: We tend to think of the universe as parsimonious. We
• 21:18
  Speaker 2: try to take every piece that we find and fit
• 21:21
  Speaker 2: it into the puzzle to explain why the universe works
• 21:23
  Speaker 2: this way.
• 21:25
  Speaker 1: Well, I guess one of the reasons we as we
• 21:27
  Speaker 1: talked about last time, that we call some things matter
• 21:29
  Speaker 1: and something's antimatter, is that we mostly see matter out
• 21:33
  Speaker 1: there in the universe, at least as far as we know.
• 21:35
  Speaker 1: Our planet, our Solar System, our galaxy is made out
• 21:38
  Speaker 1: of regular matter, and there's a big mystery about why
• 21:41
  Speaker 1: there isn't as much antimatter in the universe. But maybe
• 21:44
  Speaker 1: one question that you can ask is, like, is matter
• 21:46
  Speaker 1: and antimatter made at the same rate in the universe.
• 21:50
  Speaker 1: Like if you run a particle collision experiment and you
• 21:53
  Speaker 1: create some energy and some particles spill out to matter,
• 21:57
  Speaker 1: particles get made as much as antimatter particles.
• 22:00
  Speaker 2: A little bit on what you start from. I mean,
• 22:01
  Speaker 2: if you start from particles of matter, then you're going
• 22:04
  Speaker 2: to get more matter particles than antimatter particles. If you
• 22:07
  Speaker 2: start from antimatter particles, then you're going to get more antimatter,
• 22:10
  Speaker 2: and we actually ran a whole collider that smashed matter
• 22:13
  Speaker 2: versus antimatter. Now, was the collider outside Chicago, the Tevatron,
• 22:17
  Speaker 2: collided protons with anti protons, and so there we got
• 22:21
  Speaker 2: even splits of matter and antimatter. Whereas the collider at Cerne,
• 22:25
  Speaker 2: the Large Hadron Collider, smashes protons with protons because antimatter
• 22:30
  Speaker 2: was such a big headache to produce for the other collider,
• 22:32
  Speaker 2: And so there we get more matter produced than antimatter
• 22:35
  Speaker 2: because we're starting from matter. But most of these processes
• 22:39
  Speaker 2: are symmetric.
• 22:39
  Speaker 4: Right.
• 22:39
  Speaker 2: If you just have a big pile of photons and
• 22:41
  Speaker 2: you wait for them to decay, they will produce an
• 22:44
  Speaker 2: equal number of positrons and electrons.
• 22:47
  Speaker 1: I see. So I guess the big mystery is that
• 22:49
  Speaker 1: it sounds kind of like the universe is able to
• 22:53
  Speaker 1: make equal amounts of both kinds of matter, but what
• 22:55
  Speaker 1: we see in the universe is mostly only one kind
• 22:57
  Speaker 1: of matter.
• 22:58
  Speaker 2: Yeah, we suspect that the very early universe, matter and
• 23:01
  Speaker 2: antimatter were created at the same rates that as the
• 23:03
  Speaker 2: universe cooled down from the frothing pile of quantum fields
• 23:07
  Speaker 2: and things got cold and isolated enough that you could
• 23:10
  Speaker 2: call things particles, that the particles and anti particles existed
• 23:14
  Speaker 2: at basically the same level. Then there was a huge
• 23:16
  Speaker 2: amount of annihilation, as you can imagine, and most of
• 23:19
  Speaker 2: the matter and antimatter went away and turned into radiation.
• 23:22
  Speaker 2: But a little bit more matter is left over than antimatter,
• 23:25
  Speaker 2: and we don't understand the source of that discrepancy, even
• 23:28
  Speaker 2: though it's the reason why we have matter galaxies and matter,
• 23:32
  Speaker 2: stars and matter, people and matter chocolate and not anti matter.
• 23:36
  Speaker 2: The universe seems to have some preference for matter over antimatter.
• 23:40
  Speaker 1: Which makes me ask the question, is anti chocolate vanilla
• 23:44
  Speaker 1: or white chocolate or is it a case of having
• 23:46
  Speaker 1: multiple antiversities?
• 23:48
  Speaker 2: I hope so, because neither of those things should be
• 23:50
  Speaker 2: categorized with chocolate.
• 23:51
  Speaker 1: You're just pro chocolate. You just anti everything that's.
• 23:55
  Speaker 2: I'm just anti calling things chocolate that aren't chocolate. Even
• 23:57
  Speaker 2: calling them anti chocolate somehow groups them to get they're
• 24:00
  Speaker 2: in that chocolate category where they don't belong.
• 24:02
  Speaker 1: What about vegan chocolate, not chocolate.
• 24:05
  Speaker 2: No, totally chocolate. It comes from the cocoa bean.
• 24:07
  Speaker 1: Yeah, absolutely, all right, Well, the big question is why
• 24:11
  Speaker 1: does it exist? At all. Why do we have antimatter,
• 24:14
  Speaker 1: Like is it something that the equations of the universe
• 24:17
  Speaker 1: requires or is it just something that seems to happen.
• 24:21
  Speaker 1: That's the big question, right.
• 24:22
  Speaker 2: That's the question, and the short answer is we don't know.
• 24:26
  Speaker 2: But what's really fascinating is that without antimatter, some of
• 24:30
  Speaker 2: our basic theories of physics don't work very well together.
• 24:33
  Speaker 2: Like we have relativity and we have quantum mechanics, both
• 24:37
  Speaker 2: things that we think make sense in the universe, but
• 24:40
  Speaker 2: when we try to bring them together, we get some conflicts.
• 24:43
  Speaker 2: And it turns out that antimatter resolves those conflicts and
• 24:47
  Speaker 2: lets us bring special relativity and quantum mechanics together into
• 24:51
  Speaker 2: one theory.
• 24:52
  Speaker 1: Wait, I thought those two things didn't like each other.
• 24:54
  Speaker 2: So we have two different theories of relativity, special relativity,
• 24:58
  Speaker 2: which tells us about what happens and things move really
• 25:01
  Speaker 2: really fast near the speed of light, and then general relativity,
• 25:04
  Speaker 2: which tells us how space bends in the presence of mass.
• 25:08
  Speaker 2: General relativity and quantum mechanics we do not know how
• 25:11
  Speaker 2: to combine into a theory of quantum gravity. That's something
• 25:14
  Speaker 2: for a future physicist, maybe one of our listeners, to
• 25:16
  Speaker 2: figure out, but special relativity and quantum mechanics we do
• 25:19
  Speaker 2: know how to combine, and we've had that for many,
• 25:22
  Speaker 2: many decades. So that's basically relativistic quantum mechanics, and that
• 25:26
  Speaker 2: is something that we know how to do thinking about
• 25:28
  Speaker 2: quantum particles and moving near the speed of light, and
• 25:31
  Speaker 2: we do that all the time in our particle colliders, right,
• 25:33
  Speaker 2: it happens all the time that we have high speed particles.
• 25:37
  Speaker 2: So relativistic quantum mechanics we can do bend space, curved space.
• 25:41
  Speaker 2: Quantum mechanics we don't know how to do.
• 25:44
  Speaker 1: Interesting. Okay, So you're saying somehow antimatter and antiparticles somehow
• 25:48
  Speaker 1: make quantum mechanics and special relativity work together. What does
• 25:52
  Speaker 1: that mean?
• 25:52
  Speaker 2: So it all has to do with preserving causality, and
• 25:55
  Speaker 2: special relativity makes it really hard to think about causality,
• 25:59
  Speaker 2: to think about the order that things happen in the universe,
• 26:02
  Speaker 2: because it forces us to think about the order of
• 26:05
  Speaker 2: events in a very different way than like Newton thought
• 26:08
  Speaker 2: about things, and the way that we intuitively think about things.
• 26:11
  Speaker 2: You probably think about the universe happening as if there's
• 26:13
  Speaker 2: like a giant clock and the whole universe like ticks
• 26:16
  Speaker 2: forward and then the next thing happens, and the universe
• 26:19
  Speaker 2: ticks forward and the next thing happens. But you can
• 26:21
  Speaker 2: think of the whole universe as having like one clock,
• 26:23
  Speaker 2: so you can tell like one story about what happened
• 26:26
  Speaker 2: in the universe. Special relativity tells us that that's not
• 26:30
  Speaker 2: actually true, that there's lots of different clocks in the universe,
• 26:34
  Speaker 2: and how fast they tick depends on where you are
• 26:37
  Speaker 2: and how fast they're moving relative to you, So you
• 26:40
  Speaker 2: can actually tell lots of different stories about what happened
• 26:43
  Speaker 2: in the universe, even stories that conflict with each other,
• 26:46
  Speaker 2: that contradict each other about the order in which events happen.
• 26:51
  Speaker 1: Yeah, I know. We've talked about this before and include
• 26:53
  Speaker 1: it in our book. It's kind of this idea that
• 26:56
  Speaker 1: if two people run a race, you think that whoever
• 26:59
  Speaker 1: wins would be clear, but it sort of depends on
• 27:02
  Speaker 1: how fast they're moving and how fast the judges moving,
• 27:06
  Speaker 1: or how fast you're moving as an observer.
• 27:08
  Speaker 2: Right, Imagine two people running a race, but instead of
• 27:11
  Speaker 2: running alongside each other on a track the way people
• 27:13
  Speaker 2: typically do, imagine them starting in the same place but
• 27:16
  Speaker 2: running opposite directions. This makes it easier to think about
• 27:19
  Speaker 2: because they end up far apart from each other. If
• 27:22
  Speaker 2: you're standing at the starting line and you're not moving
• 27:24
  Speaker 2: relative to the starting line, imagine these two runners run
• 27:27
  Speaker 2: at the same speed relative to you. You call it
• 27:30
  Speaker 2: a tie. But if somebody else is flying along in
• 27:32
  Speaker 2: a spaceship alongside one of these runners, they see the
• 27:35
  Speaker 2: two runners moving at different speeds relative to them, and
• 27:38
  Speaker 2: moving clocks run slow, which means they see one of
• 27:42
  Speaker 2: these runners in slow motion relative to the other one,
• 27:45
  Speaker 2: So they'll think one of the runners wins the race
• 27:48
  Speaker 2: and the other one is slower. But another judge going
• 27:50
  Speaker 2: the opposite direction sees the same thing, but flipped. He
• 27:53
  Speaker 2: sees the first runner's clock running slow, so he thinks
• 27:56
  Speaker 2: the second runner wins the race. So who you think
• 27:59
  Speaker 2: wins the race depends on the speed you're going relative
• 28:03
  Speaker 2: to the runners. Like people can honestly disagree about the
• 28:07
  Speaker 2: order of events, did the first runner reach the finish
• 28:09
  Speaker 2: line first or did the second runner reach the finish
• 28:12
  Speaker 2: line first. This is not a case of like people
• 28:14
  Speaker 2: being confused or mistaken or getting things wrong. It means
• 28:18
  Speaker 2: that there are multiple true stories about what happened. In
• 28:22
  Speaker 2: the universe that conflict with each other.
• 28:24
  Speaker 1: Well, there's sort of one story, right, It's just when
• 28:28
  Speaker 1: you transform it between points of views, the order of
• 28:31
  Speaker 1: events changes.
• 28:32
  Speaker 2: Yeah. That sounds to me like multiple stories. But you're
• 28:34
  Speaker 2: right that we can link them together. Special relativity tells
• 28:38
  Speaker 2: us how to predict what any observer will see. And
• 28:42
  Speaker 2: what special relativity says is that different observers will see
• 28:45
  Speaker 2: the order in different events. The laws of physics are
• 28:47
  Speaker 2: consistent from frame to frame, and they predict the observers
• 28:51
  Speaker 2: tell different stories. Yeah, so you can think about that
• 28:53
  Speaker 2: as like one coherent understanding.
• 28:56
  Speaker 1: Yeah, that's what I mean. It's not like there's two realities.
• 28:59
  Speaker 1: Nobody can ever figure this out. It's more like, you know,
• 29:03
  Speaker 1: everyone has to agree on which observer they're measuring your
• 29:06
  Speaker 1: race by.
• 29:07
  Speaker 2: Right, that's right. It means that the order of events
• 29:09
  Speaker 2: is not universal, right, that it's dependent on the observer.
• 29:12
  Speaker 1: Well, or it is universal, as you said, it changes
• 29:14
  Speaker 1: depending on what you ask.
• 29:17
  Speaker 2: Yeah, it depends on the observer. Right, It's not something
• 29:19
  Speaker 2: everybody agrees on will happen from their point of view. Right,
• 29:22
  Speaker 2: Different points of view will see a different order of events,
• 29:25
  Speaker 2: and that's very confusing when you think about causality because
• 29:27
  Speaker 2: you think, like you know, there should be an order
• 29:30
  Speaker 2: two events, Like you can't finish the race before you
• 29:33
  Speaker 2: start it, you can't receive a message before you send it.
• 29:36
  Speaker 2: You can't die before you're born. There are some things
• 29:39
  Speaker 2: send in the universe where there's a causal link between them, right,
• 29:43
  Speaker 2: and so they have to happen in a certain order.
• 29:45
  Speaker 1: All right, Well, what does that mean for causality and antimatter?
• 29:48
  Speaker 2: Then well, you might think that this makes the universe nonsense,
• 29:51
  Speaker 2: because if different people can see events order different ways,
• 29:55
  Speaker 2: does not just break causality. Does that mean you can
• 29:57
  Speaker 2: eat an apple before it's grown? Does that mean you
• 29:59
  Speaker 2: can get a message before it's sent? This kind of stuff, Well,
• 30:02
  Speaker 2: special relativity has some protection built in for that, right,
• 30:06
  Speaker 2: It says this can only happen for things that are really,
• 30:09
  Speaker 2: really far apart, things that are so far apart that
• 30:12
  Speaker 2: light can't pass between them. We call these space like
• 30:16
  Speaker 2: events instead of timelike events. And so you can reorder
• 30:20
  Speaker 2: events that are really really far apart because they're already
• 30:23
  Speaker 2: not causally connected. If two things are so far apart
• 30:26
  Speaker 2: that light couldn't pass between them, then there's no way
• 30:29
  Speaker 2: for them to have a causal connection. You can't like
• 30:31
  Speaker 2: send a message from one to the other. And so
• 30:34
  Speaker 2: things that are already causally not connected. Those things you
• 30:39
  Speaker 2: can reorder by traveling at some crazy speed. Things that
• 30:42
  Speaker 2: are causally connected, Like if you turn on a flashlight
• 30:45
  Speaker 2: and then the beam arrive somewhere else, there's enough time
• 30:48
  Speaker 2: for light to get from one to the other. You
• 30:51
  Speaker 2: can't reorder those events just by going faster or.
• 30:54
  Speaker 1: Slower, all right, So then how does that figure into antimatter?
• 30:57
  Speaker 2: So these events that you can't reorder, those are things
• 31:00
  Speaker 2: we call inside our light cone. Light cone are things
• 31:03
  Speaker 2: that we can affect in our future, and there's things
• 31:06
  Speaker 2: that affected us from the past. So that special relativity,
• 31:09
  Speaker 2: and it has this nice causal connection for things inside
• 31:12
  Speaker 2: your light cone. Things outside your light cone, they can
• 31:14
  Speaker 2: get reordered by things going fast or slow. Quantum mechanics, however,
• 31:18
  Speaker 2: doesn't naturally obey this rule. Quantum mechanics has weird limitations
• 31:23
  Speaker 2: on how much you can know about objects momentums, and velocities. So,
• 31:27
  Speaker 2: for example, you measure a particle really really specifically. The
• 31:31
  Speaker 2: Heisenbergen certainty principle tells you you can't know anything about
• 31:35
  Speaker 2: its velocity, how fast it's going. So in principle, quantum
• 31:39
  Speaker 2: mechanics allows things to go faster than the speed of light.
• 31:43
  Speaker 2: That allows particles to move from one place to another
• 31:46
  Speaker 2: outside the light cone because they could be going faster
• 31:49
  Speaker 2: than the speed of light. Quantum mechanics doesn't have the
• 31:52
  Speaker 2: speed of light built into it naturally, it allows particles
• 31:56
  Speaker 2: to violate this speed limit. WHOA well.
• 32:01
  Speaker 1: On they think quantum mechanics can break the speed of light.
• 32:04
  Speaker 1: That sounds a little bit too much, Daniel. I think
• 32:06
  Speaker 1: you mean maybe, like our math allows it to, but
• 32:10
  Speaker 1: we don't know if in reality it can go faster
• 32:12
  Speaker 1: than light. Doing If you just.
• 32:13
  Speaker 2: Start from sort of low speed quantum mechanics, the original
• 32:16
  Speaker 2: quantum mechanics that was developed right, non relativistic quantum mechanics
• 32:20
  Speaker 2: for slow moving particles, then that theory with the Heisenberg
• 32:24
  Speaker 2: uncertainty principle doesn't respect the speed limit of the universe.
• 32:28
  Speaker 2: It's only when you try to bring quantum mechanics and
• 32:30
  Speaker 2: special relativity together to make a theory of relativistic high
• 32:34
  Speaker 2: speed particles that you have to answer this question like, uh, oh,
• 32:37
  Speaker 2: what happens if particles that quantum mechanics predicts can go
• 32:40
  Speaker 2: faster than the speed of light. What does special relativity
• 32:43
  Speaker 2: say about that? So it's you know, in trying to
• 32:45
  Speaker 2: bring the mathematics in harmony with the universe, that we
• 32:48
  Speaker 2: run into this problem. We're like, hold on a second.
• 32:50
  Speaker 2: Quantum mechanics has this problem with causality. It allows things
• 32:54
  Speaker 2: to move outside your light cone. What's going on and between?
• 32:59
  Speaker 2: You bring these two things together, that antiparticles save the
• 33:02
  Speaker 2: day and allow you to bring quantum mechanics and special
• 33:05
  Speaker 2: relativity together in a way that makes perfect sense.
• 33:08
  Speaker 1: I think maybe what you mean is that antimatter says
• 33:11
  Speaker 1: physicism because their original theory made no sense.
• 33:17
  Speaker 2: Yeah, you cannot bring quantum mechanics and special relativity together
• 33:20
  Speaker 2: without anti particles.
• 33:21
  Speaker 1: Right, It's like the limitations of the theory would allow
• 33:24
  Speaker 1: things to move faster than light, but probably in reality
• 33:28
  Speaker 1: they don't.
• 33:29
  Speaker 2: That's right. We think special relativity is the law of
• 33:30
  Speaker 2: the universe. Nothing moves faster than light. Original old school
• 33:33
  Speaker 2: quantum mechanics has this problem that allows things to move
• 33:36
  Speaker 2: faster than the speed of light, potentially breaking causality. And
• 33:39
  Speaker 2: you're right, we don't think that happens in reality, So
• 33:41
  Speaker 2: we need to patch up the theory, and it turns
• 33:44
  Speaker 2: out that we need antimatter in order to do that.
• 33:47
  Speaker 1: All right, well, let's dig into how antimatter saves the day.
• 33:51
  Speaker 1: It's sort of like a plot to is the villain
• 33:53
  Speaker 1: actually turns out to be the good guy. So let's
• 33:54
  Speaker 1: dig into that, and what does it mean about our
• 33:57
  Speaker 1: understanding of matter, antimatter and all kinds of matters or
• 34:00
  Speaker 1: in the universe. But first, let's take another quick break.
• 34:15
  Speaker 1: All right, we're talking about antimatter antiparticles. Why do we
• 34:18
  Speaker 1: have them? Why do we need them? It turns out
• 34:20
  Speaker 1: that they're useful in making our theories work, which is
• 34:26
  Speaker 1: not really I guess an answer to the question.
• 34:28
  Speaker 4: Is it?
• 34:28
  Speaker 2: Well, it's sort of an answer to the question. You know.
• 34:30
  Speaker 2: It says that the universe needs this to be consistent,
• 34:34
  Speaker 2: or our theories need this in order to be consistent
• 34:36
  Speaker 2: description of the universe.
• 34:38
  Speaker 1: Okay, so then you're saying that it somehow helps reconcile
• 34:41
  Speaker 1: special relativity and quantum mechanics. How does it do that?
• 34:44
  Speaker 2: So let's think about how quantum mechanics breaks causality. Right,
• 34:47
  Speaker 2: Imagine you have like a particle that you emit right
• 34:50
  Speaker 2: here at this moment, and quantum mechanics predicts that it
• 34:53
  Speaker 2: has a probability to end up like in Andromeda ten
• 34:57
  Speaker 2: seconds from now. That would break causality because if be
• 35:00
  Speaker 2: outside your leg cone, it would be like getting to
• 35:02
  Speaker 2: Andromeda faster than the speed of light. Nothing that we
• 35:05
  Speaker 2: do right now should be able to affect Andromeda until
• 35:09
  Speaker 2: millions of years into the future, because Andromeda is millions
• 35:12
  Speaker 2: of light years away.
• 35:13
  Speaker 1: I think you're saying, the quantum mechanics, we have a
• 35:15
  Speaker 1: description of a particle here, and because there's uncertainty about
• 35:19
  Speaker 1: where it can be, there's a certain probability that in
• 35:22
  Speaker 1: the next second it can be right where it is now,
• 35:25
  Speaker 1: or it can be a meter away or two meters away.
• 35:28
  Speaker 1: And there's a very very very small possibility that in
• 35:31
  Speaker 1: the next two seconds, according to the quantum mechanics, it
• 35:34
  Speaker 1: can then be in Andromeda. That's kind of how you
• 35:37
  Speaker 1: would describe it.
• 35:38
  Speaker 2: Yeah, exactly if you have a lot of uncertainty on
• 35:41
  Speaker 2: its momentum, because you've narrowed down its position super duper well,
• 35:45
  Speaker 2: and Heisenbergen certainty principle tells you can't know both things
• 35:48
  Speaker 2: at the same time. So if you know the position
• 35:50
  Speaker 2: really really well, you don't know the momentum, and therefore
• 35:53
  Speaker 2: there's a possibility that it has some crazy high momentum
• 35:56
  Speaker 2: would be faster than the speed of light, getting it
• 35:59
  Speaker 2: too Andrama in just ten seconds instead of the millions
• 36:03
  Speaker 2: of years it should take. And this would be a
• 36:05
  Speaker 2: problem for causality because those two events are spacelike. It's
• 36:09
  Speaker 2: outside of our light cone, which means that somebody flying
• 36:12
  Speaker 2: by in a spaceship could see them happen. In the
• 36:14
  Speaker 2: other order, could see this particle arrive in Andromeda before
• 36:18
  Speaker 2: it leaves our galaxy, which is nonsense. Right, So anything
• 36:22
  Speaker 2: that moves faster than the speed of light breaks causality.
• 36:25
  Speaker 2: That's one reason why we don't think things can move
• 36:27
  Speaker 2: faster than the speed of light, because it would allow
• 36:29
  Speaker 2: you to reorder events that are causally linked. Right, so
• 36:33
  Speaker 2: make the universe nonsense.
• 36:35
  Speaker 1: Well, it sort of sounds like quantum mechanics just breaks
• 36:37
  Speaker 1: causality anyways, right. Quantum mechanics say that particles can just
• 36:42
  Speaker 1: pop out of nowhere without any cause, So like quantum
• 36:46
  Speaker 1: mechanics says that a particle can suddenly disappear here and
• 36:48
  Speaker 1: appear in Andromeda.
• 36:50
  Speaker 2: Why not now, I wouldn't say that quantum mechanics necessarily
• 36:53
  Speaker 2: breaks causality. It makes a different description of the universe.
• 36:56
  Speaker 2: It makes the universe probabilistic instead of deterministic. It says
• 37:00
  Speaker 2: weird things can happen, like a photon can turn into
• 37:03
  Speaker 2: an electron and a positron, or it could do something else.
• 37:06
  Speaker 2: It says that the laws of the universe only predict
• 37:09
  Speaker 2: what might happen instead of what does actually happen. But
• 37:12
  Speaker 2: there is still causality, Like in quantum mechanics, the wave
• 37:15
  Speaker 2: function right now is determined by the wave function in
• 37:17
  Speaker 2: the past. Right The wave function itself doesn't specify exactly
• 37:21
  Speaker 2: what will happen, only to probabilities, but the wave function
• 37:24
  Speaker 2: is still determined by the past wave function, so there
• 37:26
  Speaker 2: should still be logic in quantum mechanics.
• 37:30
  Speaker 1: I guess that's weird because if you're saying that anything
• 37:32
  Speaker 1: might happen, I.
• 37:33
  Speaker 2: Would say anything might happen, you know quantum mechanics, as
• 37:36
  Speaker 2: is the probability for things to happen. Some things are
• 37:39
  Speaker 2: impossible even in quantum mechanics, like you can't violate conservation
• 37:43
  Speaker 2: of electric charge right, Electrons have no probability to turn
• 37:46
  Speaker 2: into positrons directly, because I would violate conservation of electric charge,
• 37:51
  Speaker 2: which is built into our quantum mechanical theories.
• 37:54
  Speaker 1: But haven't we talked about how like, according to quantum mechanics,
• 37:58
  Speaker 1: a pink elephant could certainly you're out of nowhere outside
• 38:01
  Speaker 1: of the Earth's orbit, right in space.
• 38:03
  Speaker 2: Yeah, that's not impossible. That doesn't break any of the rules.
• 38:06
  Speaker 1: But then we have no cause would it.
• 38:08
  Speaker 2: Well, the cause would be that there's a distribution of
• 38:10
  Speaker 2: probabilities for what those particles in the vacuum could do.
• 38:14
  Speaker 2: They could sit there and do nothing. They could create
• 38:16
  Speaker 2: one electron, they could create ten electrons, they could create
• 38:20
  Speaker 2: forty two trillion electrons. They could create a Boltzmann brain,
• 38:23
  Speaker 2: they could create a pink elephant. Those things are probabilities.
• 38:26
  Speaker 2: What does our universe choose one particular probability and not another?
• 38:30
  Speaker 2: What does it choose one that's like really unlikely, like
• 38:32
  Speaker 2: a pink elephant in space, and not another that's more
• 38:35
  Speaker 2: likely that we don't understand. That's like a deep question
• 38:38
  Speaker 2: in quantum philosophy, whether all of them happen at once
• 38:41
  Speaker 2: in different universes, whether the universe collapses these wave functions
• 38:45
  Speaker 2: to choose one. Whether it even is truly random, That
• 38:48
  Speaker 2: is definitely not something we know. But I wouldn't say
• 38:50
  Speaker 2: there's no cause there's still like a distribution of probabilities
• 38:53
  Speaker 2: for what might happen.
• 38:54
  Speaker 1: Well, let's get back to the antimatter particle. How does
• 38:57
  Speaker 1: that antimatter particle fit into this scenario.
• 38:59
  Speaker 2: Then it turns out if you do these calculations, and
• 39:01
  Speaker 2: you calculate like, okay, what's the probability for my particle
• 39:04
  Speaker 2: to appear in and Drama in ten seconds from now,
• 39:06
  Speaker 2: and you include antimatter, then those probabilities vanish. Because the
• 39:11
  Speaker 2: probability for you to see a particle go to Andrama
• 39:14
  Speaker 2: in ten seconds, there's another probability for a particle to
• 39:18
  Speaker 2: go from Andromeda to here in ten seconds, for an
• 39:21
  Speaker 2: antimatter particle to come the opposite direction. And because matter
• 39:26
  Speaker 2: and antimatter have all the opposite properties, those two things
• 39:29
  Speaker 2: quantum mechanically cancel each other out. So the antimatter nonsense
• 39:34
  Speaker 2: cancels out the matter nonsense to make no nonsense. Whoa, whoa, whoa.
• 39:39
  Speaker 1: Wait, we had this scenario of having one particle here
• 39:41
  Speaker 1: that suddenly appears in Andromeda in ten seconds. You're saying,
• 39:44
  Speaker 1: there's a different scenario in which an anti particle the
• 39:49
  Speaker 1: exact antiparticle of my particle is where my particle would appear.
• 39:54
  Speaker 1: That one disappears and appears where my current particle is
• 39:58
  Speaker 1: at the same time, and somehow that cancels it out.
• 40:01
  Speaker 1: But what are the chances that there's an antiparticle exactly
• 40:04
  Speaker 1: where my particle would go.
• 40:07
  Speaker 2: Well, all of this stuff is very unlikely. But when
• 40:09
  Speaker 2: you do a quantum mechanical calculation, you sum over all
• 40:12
  Speaker 2: the possibilities, and these equations are wave equations, so you
• 40:16
  Speaker 2: can get like constructive interference and destructive interference and things
• 40:19
  Speaker 2: where the probabilities cancel out, those things just don't happen.
• 40:22
  Speaker 2: Like in the Devil's Slight experiment. You see interference places
• 40:25
  Speaker 2: where lots of particles and places with no particles, the
• 40:28
  Speaker 2: places where no particles land, and the interference on the
• 40:31
  Speaker 2: screen is because there's been destructive interference among the probabilities.
• 40:35
  Speaker 2: So when the probabilities cancel out, those things just don't
• 40:38
  Speaker 2: happen in the universe, And so the probability for a
• 40:41
  Speaker 2: particle to break special relativity and appear in Andromeda is
• 40:45
  Speaker 2: canceled out by the probability for an antiparticle to do
• 40:48
  Speaker 2: the opposite.
• 40:49
  Speaker 1: Well, I guess what does it mean to cancel out
• 40:51
  Speaker 1: the probability? That means that it's never going to happen.
• 40:53
  Speaker 2: It means that it's never going to happen. And so
• 40:56
  Speaker 2: if you bring quantum mechanics and special relativity together, you
• 41:00
  Speaker 2: include anti particles, then it all clicks together perfectly and
• 41:04
  Speaker 2: you get no violations of causality.
• 41:06
  Speaker 1: But wait, the wouldn't that also cancel all movements like
• 41:10
  Speaker 1: even a meter distance?
• 41:13
  Speaker 2: Yeah, great question. It doesn't happen for things inside the
• 41:16
  Speaker 2: light cone because things inside the light cone everybody agrees
• 41:19
  Speaker 2: on the order, whereas things outside the light cone you
• 41:22
  Speaker 2: can reorder them. So, for example, if I say, well, look,
• 41:25
  Speaker 2: my particle left here and ended up in a drama
• 41:28
  Speaker 2: in ten seconds, that's outside my light cone. So somebody
• 41:31
  Speaker 2: else flying by in a spaceship might see them happen
• 41:33
  Speaker 2: in the opposite order. Right. Seeing it happen in the
• 41:36
  Speaker 2: opposite order is like seeing a particle go backwards in time,
• 41:39
  Speaker 2: which is equivalent to the anti matter particle. Right, So
• 41:43
  Speaker 2: both probabilities exist, the particle and anti particle version, because
• 41:48
  Speaker 2: you can reorder them because they are outside your light cone.
• 41:51
  Speaker 2: Things inside your light cone, you can't reorder them. Their
• 41:54
  Speaker 2: order is fixed. Only things outside the light cone where
• 41:57
  Speaker 2: you could reorder them, where somebody could see it as
• 41:59
  Speaker 2: a part article and the other person could see it
• 42:01
  Speaker 2: as an anti particle. Only those things cancel out.
• 42:04
  Speaker 1: It feels a little convenient, like maybe saying like, oh,
• 42:07
  Speaker 1: my theory breaks down after this limit. Let's just come
• 42:10
  Speaker 1: up with something totally different and ex sort it only
• 42:13
  Speaker 1: applies outside of this limit where my thing breaks.
• 42:16
  Speaker 2: Yeah. Well, it's sort of convenient and sort of spooky, right.
• 42:19
  Speaker 2: It's sort of like if you didn't know antiparticles existed
• 42:22
  Speaker 2: and you were trying to bring quantum mechanics and relativity
• 42:24
  Speaker 2: together into relativistic quantum mechanics, You're like, huh, this is
• 42:28
  Speaker 2: a problem. This could be solved if, for example, there
• 42:31
  Speaker 2: were the existence of antimatter hmm, and then you went
• 42:34
  Speaker 2: out in the universe and you found it, You'd be like, wow,
• 42:36
  Speaker 2: that was pretty cool. Here it's sort of works the
• 42:38
  Speaker 2: opposite direction. We're like, no antimatter exists, and we can
• 42:42
  Speaker 2: use it to help bring these two theories together. It
• 42:44
  Speaker 2: is very convenient, but that's sort of like a glorious
• 42:47
  Speaker 2: moment when you're like, oh wow, look these things. They
• 42:49
  Speaker 2: sort of need to exist for the universe to be
• 42:52
  Speaker 2: self consistent.
• 42:53
  Speaker 1: Now, you said something earlier that was kind of interesting.
• 42:55
  Speaker 1: You said, anti particles kind of go back in time.
• 42:57
  Speaker 1: What does that mean?
• 42:58
  Speaker 2: Well, mathematically you can look at it a particle moving
• 43:00
  Speaker 2: forwards in time, and it's equivalent to an antimatter particle
• 43:04
  Speaker 2: moving backwards in time. And you can sort of see
• 43:06
  Speaker 2: that in this example we're talking about, where like, my
• 43:09
  Speaker 2: particle goes from here to Andromeda, and it does it
• 43:12
  Speaker 2: faster than the speed of light. Right. If it does
• 43:14
  Speaker 2: it faster than the speed of light, that means that
• 43:16
  Speaker 2: somebody else going by in a spaceship they could see
• 43:18
  Speaker 2: it happen in the opposite order. They could see it
• 43:20
  Speaker 2: arrive in Andromeda before it leaves my house in the
• 43:25
  Speaker 2: milky way, right, which means that it's started in Andromeda.
• 43:28
  Speaker 2: The first event is in Andromeda. So I could say, look,
• 43:31
  Speaker 2: this is a particle going forwards in time faster than
• 43:33
  Speaker 2: the speed of light. Somebody else could say, no, it
• 43:36
  Speaker 2: goes the other direction. They could say, no, it's going
• 43:38
  Speaker 2: from your future to your past. But I see it
• 43:41
  Speaker 2: as an antimatter particle because they could reorder the events,
• 43:44
  Speaker 2: and so they see it going from Andromeda to the
• 43:47
  Speaker 2: Milky Way, and they see it moving as an antimatter particle.
• 43:50
  Speaker 1: But I guess maybe in order to measure my particle
• 43:53
  Speaker 1: here and there, don't I need to measure the particle,
• 43:56
  Speaker 1: wouldn't they collapse the wave function and make this all
• 43:59
  Speaker 1: kind of not really applicable.
• 44:00
  Speaker 2: You would need to collapse the wave function absolutely, and
• 44:03
  Speaker 2: of course it wouldn't really happen, right. That probability is
• 44:05
  Speaker 2: actually zero. You can't collapse the wave function and make
• 44:08
  Speaker 2: this happen. What we're talking about really is just a
• 44:10
  Speaker 2: partial probability. There's another part to that calculation, the antimatter part,
• 44:14
  Speaker 2: that cancels it out. So you can't actually do this right.
• 44:17
  Speaker 2: You can't see a particle appear in Andromeda in ten seconds.
• 44:21
  Speaker 2: It would take millions of years to get there, and
• 44:23
  Speaker 2: the probability for that to happen is canceled out by
• 44:25
  Speaker 2: the anti matter version, So that's why it just doesn't happen.
• 44:28
  Speaker 1: Is this sort of like one of those virtual particle
• 44:30
  Speaker 1: scenarios where like just a matter of fact that something
• 44:33
  Speaker 1: else can happen, actually in a way happens canceling out
• 44:38
  Speaker 1: other effects that are happening.
• 44:40
  Speaker 2: Yeah, you can think about this the way other quantum
• 44:42
  Speaker 2: mechanical weirdness happens, where like particles can interfere with themselves.
• 44:46
  Speaker 2: Right again, like in the double slit experiment, if you
• 44:48
  Speaker 2: don't know which slit the particle went through, has a
• 44:51
  Speaker 2: probability to go through both, and those probabilities can actually
• 44:54
  Speaker 2: interfere with themselves, So single particle interferes with itself. This
• 44:58
  Speaker 2: is sort of the same deal. Like this single particle
• 45:01
  Speaker 2: that goes from here to Andromeda, you could also be
• 45:03
  Speaker 2: seen as an antimatter particle going the other direction, and
• 45:06
  Speaker 2: those two probabilities cancel, which is why it never actually happens.
• 45:10
  Speaker 1: All right, Well, then what is the I guess main
• 45:12
  Speaker 1: takeaway is it that quantum mechanics does work with special activity,
• 45:16
  Speaker 1: and it's because antimatter particles exist or are a possibility
• 45:21
  Speaker 1: in the universe.
• 45:22
  Speaker 2: That's exactly right. You need antimatter to bring quantum mechanics
• 45:26
  Speaker 2: and special relativity together and not break causality. If we
• 45:30
  Speaker 2: think the universe is causal, meaning that like there's a
• 45:33
  Speaker 2: logical flow to things, that the past influences the future
• 45:37
  Speaker 2: and not the deep past. Then you need antimatter in
• 45:40
  Speaker 2: order to have special relativity and quantum mechanics. We just
• 45:43
  Speaker 2: don't know how to do it without antimatter.
• 45:45
  Speaker 1: Cool. All right, well, you've commissed me. I'm pro antimatter
• 45:50
  Speaker 1: or I'm not anti antimatter.
• 45:51
  Speaker 2: Does that mean that you're pro anti vanilla, which means
• 45:54
  Speaker 2: you're willing to try some chocolate.
• 45:55
  Speaker 1: I am pro anything with the word vanilla in it.
• 46:00
  Speaker 2: Right, I'm part of the vanilla eradication project. How do
• 46:02
  Speaker 2: you feel?
• 46:03
  Speaker 1: Oh my god? And that is how this podcast got canceled. Daniel.
• 46:10
  Speaker 1: Thank you, it's been a nice run. We're done.
• 46:13
  Speaker 2: No, I love vanilla. Vanilla is wonderful.
• 46:15
  Speaker 1: We've gone the way of Scott Adams and Dilbert.
• 46:19
  Speaker 2: I'm not a flavorist. Okay, I'm definitely pro vanilla.
• 46:22
  Speaker 1: I'm just more we think they're flavorists.
• 46:24
  Speaker 2: Daniel, I need to go for some flavor sensitivity training.
• 46:29
  Speaker 1: It sounds like, thank you, maybe you should examine those
• 46:34
  Speaker 1: anti FeAs.
• 46:37
  Speaker 2: All right, well, between this and the next episode, I
• 46:39
  Speaker 2: will do a deep dive into my own internal flavor preferences.
• 46:43
  Speaker 1: There you go examine your own anti matter. All right, Well,
• 46:47
  Speaker 1: another interesting bit of how we're trying to figure out
• 46:50
  Speaker 1: how the universe works, and how sometimes it's interesting how
• 46:53
  Speaker 1: our theories of the universe actually kind of turn out
• 46:56
  Speaker 1: to be true, which is kind of surprising, right.
• 46:58
  Speaker 2: It is surprising sometimes, and that crazy little human brains
• 47:02
  Speaker 2: can come up with mathematical stories that do seem to
• 47:04
  Speaker 2: describe the universe, even in ways we didn't anticipate.
• 47:08
  Speaker 1: All right, Well, thanks for joining us. We hope you
• 47:10
  Speaker 1: enjoyed that. See you next time.
• 47:14
  Speaker 2: Hey, everyone, I want to take a moment and share
• 47:17
  Speaker 2: a personal message with you. When I record these podcasts,
• 47:20
  Speaker 2: there's no live audience here, and so I have no
• 47:22
  Speaker 2: idea really how they're going to be received. So I
• 47:25
  Speaker 2: love hearing that they have an impact on people's lives,
• 47:28
  Speaker 2: maybe inspiring you to think about the universe, or talk
• 47:31
  Speaker 2: to your kids about physics, or even just keep your
• 47:34
  Speaker 2: brain going on long drive or a boring shift at work.
• 47:38
  Speaker 2: That's what gives me the energy to keep making these
• 47:40
  Speaker 2: to put them out twice a week without fail for
• 47:43
  Speaker 2: five years now. So it really heartens me to hear
• 47:46
  Speaker 2: from you. But I realize that you all don't get
• 47:48
  Speaker 2: to know each other as much to hear about these experiences.
• 47:51
  Speaker 2: So I want to share a little bit with you,
• 47:53
  Speaker 2: including an example that made me smile and one that
• 47:56
  Speaker 2: frankly brought some tears to my eyes. First, a happy one,
• 47:59
  Speaker 2: someone writes and says, I don't have a question but
• 48:02
  Speaker 2: a compliment. Just wanted to let both of you know
• 48:04
  Speaker 2: that I greatly appreciate the way you both explain physics.
• 48:07
  Speaker 2: As a person who has no science background and barely
• 48:09
  Speaker 2: passed college algebra, it's refreshing to hear people explain things
• 48:12
  Speaker 2: without talking down to the listener. That's wonderful and it's
• 48:16
  Speaker 2: exactly what we're trying to do, make physics more accessible
• 48:19
  Speaker 2: to everybody without dumbing it down at all. But some
• 48:22
  Speaker 2: of the messages we get are a little bit harder
• 48:24
  Speaker 2: to hear. A woman wrote in that her brother is
• 48:26
  Speaker 2: a listener and an ultrarunner, but that at thirty nine
• 48:30
  Speaker 2: he had a massive stroke and faces a long recovery.
• 48:33
  Speaker 2: She writes that quote each night he makes sure his
• 48:36
  Speaker 2: phone is charged and loaded with enough Daniel and Jorgey
• 48:39
  Speaker 2: to get him through the night. It's without drama that
• 48:42
  Speaker 2: I say that your show is one of his lifelines,
• 48:45
  Speaker 2: right now, you guys are his intellectual support above all,
• 48:49
  Speaker 2: on behalf of our family. I want to thank you
• 48:51
  Speaker 2: for your podcast and being a comfort to him in
• 48:53
  Speaker 2: this season. Wow, it's hard to overstate how deeply that
• 48:59
  Speaker 2: touches me, and I want to send him our encouragement
• 49:02
  Speaker 2: on his road to recovery. I'm so glad that we
• 49:05
  Speaker 2: can be there to help in this small way, and
• 49:08
  Speaker 2: I want to say thank you to everyone out there,
• 49:10
  Speaker 2: those of you who are listening and writing back or
• 49:12
  Speaker 2: just enjoying silently. You're all the reason that I do this.
• 49:23
  Speaker 2: Thanks for listening, and remember that Daniel and Jorge explain
• 49:26
  Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
• 49:30
  Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
• 49:35
  Speaker 2: you listen to your favorite shows.