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Does anti-matter feel anti-gravity? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Jorgey, do you have your antimatter snack yet? I
• 0:11
  Speaker 1: had a banana as usual. It's anti slip. Does that count? No?
• 0:17
  Speaker 1: But you do know that bananas give off antimatter radiation,
• 0:21
  Speaker 1: don't you wait? What that's bananas? Isn't that dangerous. It's
• 0:26
  Speaker 1: so little that it doesn't really matter. That's why you're
• 0:29
  Speaker 1: so matter of fact about it. That's why it annihilated
• 0:32
  Speaker 1: my taste for bananas. Well, the important thing is that
• 0:34
  Speaker 1: it annihilates your hunger. That's the whole point of eating food,
• 0:37
  Speaker 1: is the antimatter of hunger. Hi am or Handy, cartoonist
• 0:55
  Speaker 1: and the creator of PhD comics. Hi, I'm Daniel. I'm
• 0:58
  Speaker 1: a particle physicist and a professor at U C Irvine.
• 1:01
  Speaker 1: And it really has been years since I had a banana. Years.
• 1:05
  Speaker 1: Oh my gosh, I feel sorry for you. Why are
• 1:08
  Speaker 1: you depriving yourself and one of life's simplest pleasures. Although
• 1:12
  Speaker 1: I recently convinced my daughter to start eating bananas, so
• 1:15
  Speaker 1: now we have bananas around the house. Oh my goodness. Wait,
• 1:18
  Speaker 1: why are you recommending it to your daughter but not
• 1:21
  Speaker 1: having any yourself. You know, it's a very personal question,
• 1:24
  Speaker 1: person to person, I mean you brought it up, and
• 1:26
  Speaker 1: I'm just asking a fallow up question. I just mean
• 1:29
  Speaker 1: that it's subjective. You know, one person can love bananas,
• 1:32
  Speaker 1: another person can hate them. To slippery slope, some people
• 1:36
  Speaker 1: find them appealing. Welcome to a podcast Daniel and Jorge
• 1:39
  Speaker 1: Explained the Universe, a production of Our Heart Radio in
• 1:42
  Speaker 1: which we try to explain our subjective, our personal experience
• 1:46
  Speaker 1: of the universe the way that it seems to us.
• 1:49
  Speaker 1: All this data that we gather with our eyeballs, biological
• 1:52
  Speaker 1: and technological, the things that we see out there in
• 1:55
  Speaker 1: the universe, we want to understand all of them. We
• 1:58
  Speaker 1: want the whole universe to be a story that makes
• 2:01
  Speaker 1: sense to the human brain. This is part of course,
• 2:04
  Speaker 1: the long journey of science and trying to wrap up
• 2:07
  Speaker 1: the mysteries of the cosmos into something we understand. And
• 2:10
  Speaker 1: our goal on this podcast is to take you on
• 2:12
  Speaker 1: that journey and explain all of it to you. Yeah,
• 2:15
  Speaker 1: because it is a very mysterious universe, full of amazing
• 2:18
  Speaker 1: things that are happening in it, and a lot of
• 2:20
  Speaker 1: things that we don't understand, even things that we take
• 2:23
  Speaker 1: for granted on an everyday basis. Yeah, there are so
• 2:25
  Speaker 1: many basic questions about the universe that we do not
• 2:29
  Speaker 1: have answers to, which means that for you young folks listening,
• 2:32
  Speaker 1: you future scientists, there are plenty of discoveries left to
• 2:36
  Speaker 1: be made, lots and lots of open questions for you
• 2:39
  Speaker 1: to explore. These are big questions about the universe, about
• 2:42
  Speaker 1: our very existence, of why we're here and how it
• 2:45
  Speaker 1: is that we are here because there is a lot
• 2:48
  Speaker 1: of the things in the universe that matter, and also
• 2:50
  Speaker 1: a lot of things that antimatter, like bananas. I wasn't
• 2:53
  Speaker 1: joking that bananas produced antimatter. That's a real thing. Oh yeah,
• 2:56
  Speaker 1: But is an antimatter dangerous? Like if you touch antimatter,
• 2:58
  Speaker 1: you explode anti matter. When it hits real matter, it
• 3:01
  Speaker 1: will annihilate into photons. But bananas contain potassium, which is unstable.
• 3:07
  Speaker 1: It undergoes radioactive decay, emitting positrons, which are anti electrons,
• 3:12
  Speaker 1: and when those do hit your body, they will annihilate
• 3:15
  Speaker 1: and create a tiny little flash of light. But it's
• 3:17
  Speaker 1: such a tiny amount of antimatter that it doesn't really matter. Well,
• 3:21
  Speaker 1: that's why I eat bananas, because you know, it makes
• 3:23
  Speaker 1: me glow, makes me feel lighter too. There isn't potassium
• 3:27
  Speaker 1: in everything. I mean, it's all around us too, right,
• 3:29
  Speaker 1: It's not just bananas that have potassium. That's right. It's
• 3:32
  Speaker 1: not just bananas that have potassium. And it's all sorts
• 3:34
  Speaker 1: of other things that also radioactively decay. So it's actually
• 3:37
  Speaker 1: anti matter sort of all around us all the time.
• 3:39
  Speaker 1: It's also showering down on us from the atmosphere because
• 3:43
  Speaker 1: of cosmic ray impacts. Yeah, there are all kinds of
• 3:47
  Speaker 1: amazing things showering us at the moment right now and
• 3:50
  Speaker 1: enveloping us, and and for a lot of those things,
• 3:52
  Speaker 1: we still have big questions about them, even big things
• 3:55
  Speaker 1: like gravity. Anti matter is fascinating. It appears in science fiction,
• 3:59
  Speaker 1: but it's also some thing that's real. It's one of
• 4:01
  Speaker 1: these interesting hints that the universe is more complex than
• 4:05
  Speaker 1: just the stuff that we are made out of, that
• 4:07
  Speaker 1: the universe is capable of doing many more things than
• 4:10
  Speaker 1: can just be found out of the particles that we
• 4:12
  Speaker 1: are made of. There are all sorts of other weird
• 4:15
  Speaker 1: possible particles out there, and they all give us hints
• 4:17
  Speaker 1: about what the underlying rules are governing the universe itself.
• 4:22
  Speaker 1: And you're right, because ant matter is so rare. There
• 4:24
  Speaker 1: are basic questions we have about its properties, Yeah, including
• 4:28
  Speaker 1: something as basic as gravity, gravity, which you know we
• 4:32
  Speaker 1: kind of depend on every day of our lives to
• 4:35
  Speaker 1: stay on planet Earth. Without gravity, we'd all be floating
• 4:37
  Speaker 1: out there in space. That's not something I ever worry about,
• 4:40
  Speaker 1: but maybe I should start to do. We need to
• 4:42
  Speaker 1: like look at the gravity prediction every day as well
• 4:44
  Speaker 1: as the weather prediction. Well, I know it's a heavy
• 4:46
  Speaker 1: burden to be carrying around worrying about gravity, but it
• 4:49
  Speaker 1: seems to be pretty reliable. Right. We ever noticed any
• 4:52
  Speaker 1: change in your gravity? I mean, I don't want to
• 4:55
  Speaker 1: enquire about your weight or anything like that. That's also
• 4:58
  Speaker 1: personal information. That definitely explains it. Right, It's not that
• 5:02
  Speaker 1: I'm getting heavier and heavier. It's at the gravity of
• 5:04
  Speaker 1: the Earth itself is increasing. Sounds like you have an
• 5:07
  Speaker 1: amazing experiment in at hand here, But it does raise
• 5:11
  Speaker 1: a lot of interesting questions about gravity and antimatter, specifically
• 5:16
  Speaker 1: whether or not they are the same for everything in
• 5:20
  Speaker 1: the universe. That's right, antimatter seems to be like the
• 5:23
  Speaker 1: opposite of matter in so many interesting ways, and so
• 5:26
  Speaker 1: people also wonder whether or not antimatter falls down or
• 5:31
  Speaker 1: whether it might possibly fall up, like does antimatter fail upwards?
• 5:37
  Speaker 1: So today on the program we'll be tackling the question
• 5:45
  Speaker 1: does antimatter feel anti gravity? Interesting? Now, are you saying
• 5:50
  Speaker 1: it might feel anti gravity or it has anti feelings
• 5:54
  Speaker 1: against gravity? We should invite it onto the podcast to
• 5:56
  Speaker 1: ask it what its emotional response is to gravity. But
• 6:00
  Speaker 1: I think today we're focusing on a more physics question,
• 6:03
  Speaker 1: which is just like, when gravity does this thing, where
• 6:06
  Speaker 1: does antimatter go? Doesn't like run away from gravity? Is
• 6:10
  Speaker 1: that what you mean? Because antimatter is the opposite of
• 6:12
  Speaker 1: matter in so many interesting ways, Yet we also really
• 6:16
  Speaker 1: don't understand how gravity works for fundamental particles. We think
• 6:21
  Speaker 1: about gravity in terms of like boulders or basketballs, or baseballs,
• 6:25
  Speaker 1: or even little bits of sand, But once we get
• 6:28
  Speaker 1: down to the quantum level, those particles do things that baseball's,
• 6:31
  Speaker 1: basketballs and bits of sand can't do, and we don't
• 6:34
  Speaker 1: really know how to apply gravity to those situations, which
• 6:38
  Speaker 1: opens up all sorts of questions like maybe it does
• 6:41
  Speaker 1: the opposite of what it does for normal matter. Do
• 6:43
  Speaker 1: you think antimatter minds that we call it antimatter? Like
• 6:47
  Speaker 1: maybe it just has a different opinion about the universe.
• 6:49
  Speaker 1: You know, maybe it's just pro something else. Yeah, I
• 6:52
  Speaker 1: think in the antimatter galaxies that might be out there
• 6:55
  Speaker 1: in deep space. On their podcast, they're probably calling us
• 6:58
  Speaker 1: the antimatter yeah. Or maybe there's a third opinion, you know,
• 7:01
  Speaker 1: why does it have to be so adversarial these politics
• 7:04
  Speaker 1: of physics? Stop the polarization of physics exactly, it's all
• 7:08
  Speaker 1: just matter. Yeah, it's not helping our society for sure. Well,
• 7:12
  Speaker 1: as usual, we were wondering how many people have thought
• 7:14
  Speaker 1: about anti matter and whether it feels gravity, or whether
• 7:18
  Speaker 1: it feels anti gravity, or whether anti feels gravity. So
• 7:23
  Speaker 1: thanks very much to everybody who participates in this segment
• 7:26
  Speaker 1: of the podcast. If you would like to try answering
• 7:29
  Speaker 1: the question of the day, please feel free to write in.
• 7:32
  Speaker 1: We'll set you up and you can hear your voice
• 7:34
  Speaker 1: on the podcast. Think about it for a second. Do
• 7:36
  Speaker 1: you think antimatter falls down or up? Here's what people
• 7:41
  Speaker 1: had to say, pravity, because anti gravity might be things
• 7:44
  Speaker 1: pushing each other apart. What do you think gravity or
• 7:47
  Speaker 1: anti gravity? I feel like anti matter still has mass.
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  Speaker 1: It doesn't have like anti mass, so I don't think
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  Speaker 1: it feels anti gravity. Do we know if there's anti gravity?
• 8:00
  Speaker 1: Is their uncle gravity? I think that antimatter feel gravity
• 8:03
  Speaker 1: in the same way that normal matter feels gravity, and
• 8:08
  Speaker 1: anti gravity, I think is we don't know if that
• 8:11
  Speaker 1: even exists. Well, if I remember your lessons on anti matter,
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  Speaker 1: it should feel gravity because any matter is just regular
• 8:19
  Speaker 1: matter with opposite chart. I know that matter feels gravity
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  Speaker 1: because of the bending of spacetime towards something with mass.
• 8:26
  Speaker 1: I don't really know what anti matter is and whether
• 8:29
  Speaker 1: it exists in another field or spatial field than mass.
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  Speaker 1: But I suppose in the field that anti matter exists,
• 8:38
  Speaker 1: maybe there's the bending of that field, which would be
• 8:41
  Speaker 1: called anti gravity, So I'd say it does feel anti gravity. Alright,
• 8:45
  Speaker 1: a lot of very pro and anti pocisitions on this question.
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  Speaker 1: My emotions go up and down as I was listening
• 8:51
  Speaker 1: to those things. I like how people were anti knowing
• 8:55
  Speaker 1: an answer. What happens when knowledge collides with anti knowledge.
• 8:59
  Speaker 1: You probably get the current state of affairs right now
• 9:02
  Speaker 1: in the world. You get a physics podcast about the
• 9:04
  Speaker 1: mysteries of the universe. But it is an interesting question
• 9:07
  Speaker 1: whether antimatter feels anti gravity, because I guess antimatter feels
• 9:12
  Speaker 1: natively about a lot of things. Yeah, antimatter is one
• 9:15
  Speaker 1: of my favorite ideas in physics because it shows you
• 9:18
  Speaker 1: that our matter isn't the only kind of matter that
• 9:21
  Speaker 1: can be out there. There's like the opposite of our
• 9:24
  Speaker 1: kind of matter. Though, like what exactly opposite means is
• 9:27
  Speaker 1: a bit of a question philosophically, Right, Well, I guess
• 9:30
  Speaker 1: maybe start with the basics what is matter for of all?
• 9:34
  Speaker 1: Because I know there are matter particles and there are
• 9:37
  Speaker 1: force particles, right, I think the basic idea is that
• 9:40
  Speaker 1: the universe is filled with quantum fields, and some of
• 9:43
  Speaker 1: these are matter quantum fields. Right. Yeah, what we call
• 9:46
  Speaker 1: matter is what you and I are made out of.
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  Speaker 1: We call it matter because it's the first thing we discovered,
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  Speaker 1: and so we sort of named it the normal stuff.
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  Speaker 1: And you and I are made of these particles electrons
• 9:57
  Speaker 1: and protons and neutrons, which are of course made up
• 9:59
  Speaker 1: of core works inside them. And as you say, they
• 10:02
  Speaker 1: are all bound together by forces, the electromagnetic force, the
• 10:05
  Speaker 1: weak nuclear force, the strong force, which all use particles
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  Speaker 1: to communicate with each other. So there's like the photon
• 10:12
  Speaker 1: for the electromagnetic force and the gluon for the strong
• 10:15
  Speaker 1: nuclear force. And so you and I are like this
• 10:18
  Speaker 1: big complicated mesh of particles all weaving themselves together to
• 10:22
  Speaker 1: make me and you. Right, and we are made out
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  Speaker 1: of the basic three kinds of matter particles, right, electrons,
• 10:29
  Speaker 1: and one type of forks, and another type of cork.
• 10:33
  Speaker 1: And wait, a third type of cork. Right, three courts?
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  Speaker 1: How many quarks are there? There are six quarks that
• 10:38
  Speaker 1: we have discovered, the up cork and the down cork.
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  Speaker 1: Those two are the ones that we find mostly in
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  Speaker 1: the proton and the neutron, although there is a little
• 10:47
  Speaker 1: bit of other kinds of quirks sometimes appearing in the
• 10:50
  Speaker 1: proton and neutron, but for the most part, it's up
• 10:52
  Speaker 1: quarks and down corks make protons and neutrons, and you
• 10:55
  Speaker 1: add electrons to complete the atom. Right, So we're made
• 10:58
  Speaker 1: out of those kinds of icles, and most of most
• 11:01
  Speaker 1: of the stuff in the universe is made out of
• 11:02
  Speaker 1: those three particles, right, Like the planets, the stars, the
• 11:06
  Speaker 1: comments out there, the asteroids, the whole galaxies are basically
• 11:09
  Speaker 1: those three kinds of particles. Right. Yeah, we think that
• 11:12
  Speaker 1: our entire solar system, our entire galaxy, our cluster of
• 11:16
  Speaker 1: galaxy is all made out of this same kind of
• 11:18
  Speaker 1: basic stuff that these basic building blocks can be put
• 11:21
  Speaker 1: together in lots of different ways to make stars and
• 11:24
  Speaker 1: lava and weasels and peanut butter and all the stuff
• 11:26
  Speaker 1: that we know in the universe. And that's why we
• 11:29
  Speaker 1: call it matter. And on a semantic note, I would
• 11:31
  Speaker 1: include also the force particles, you know, the gluons and
• 11:34
  Speaker 1: the photons and things that tie them together to really
• 11:37
  Speaker 1: make them who we are. So we're not just like
• 11:39
  Speaker 1: a loose pile of particles as constituting matter in this case.
• 11:43
  Speaker 1: I know, sometimes particle physicists distinguished between matter particles and
• 11:47
  Speaker 1: force particles, but when we're talking about matter and versus antimatter,
• 11:50
  Speaker 1: I think it makes more sense to just lump it
• 11:52
  Speaker 1: all together as matter. Okay, shifting definitions here of basic
• 11:57
  Speaker 1: things like matter and force. I guess we're all a
• 11:59
  Speaker 1: little bit das to that. But also that's the stuff
• 12:02
  Speaker 1: that we're made out of. But there's also other stuff
• 12:05
  Speaker 1: in the universe in this category of matter, right, there's
• 12:08
  Speaker 1: like heavier electrons and heavier courts. Yes, there are other
• 12:11
  Speaker 1: versions of these particles. This is one of the really
• 12:14
  Speaker 1: fascinating things about particle physics is that the particles we know,
• 12:18
  Speaker 1: the electron, the upcork, and the down cork have these reflections.
• 12:22
  Speaker 1: That's what I meant earlier about the sort of philosophical
• 12:24
  Speaker 1: definition of opposite. Because with the particles we know, there
• 12:27
  Speaker 1: are several versions of them. So even before we talk
• 12:30
  Speaker 1: about antimatter, as you said, there are heavier versions of
• 12:33
  Speaker 1: these particles, so they're sort of reflected in this one
• 12:36
  Speaker 1: dimension along mass. So there's like a heavier version of
• 12:39
  Speaker 1: the electron it's called a muon, and a heavier version
• 12:42
  Speaker 1: of the up cork it's called a charm cork. And
• 12:44
  Speaker 1: then there's a second reflection, right, So there's the muan
• 12:47
  Speaker 1: and then the towel is the upcork, the charm cork,
• 12:50
  Speaker 1: and then the top cork. So each of these basic
• 12:52
  Speaker 1: particles of matter that we know, there's two more versions
• 12:55
  Speaker 1: of each of them. So it's this weird reflection of
• 12:59
  Speaker 1: the kinds of matter that we're familiar with along the
• 13:02
  Speaker 1: mass access they're heavier versions of each of these. Well,
• 13:05
  Speaker 1: not all the particles, right, the force particles don't have
• 13:08
  Speaker 1: heavier cousins, do they. Yeah, that's right. Only the fermions
• 13:12
  Speaker 1: have these heavier cousins. We're not aware of any heavier
• 13:15
  Speaker 1: version of the photon or the z boson. Okay, but
• 13:18
  Speaker 1: there is something called antimatter particles, which is like if
• 13:21
  Speaker 1: you take all of those particles you mentioned, the ones
• 13:23
  Speaker 1: we're made out of their heavier cousins. And also in
• 13:27
  Speaker 1: some ways, if you also take the force particles and
• 13:30
  Speaker 1: numpit amount in, there's a whole other version of all
• 13:33
  Speaker 1: of those particles that are called antimatter. That's exactly right.
• 13:36
  Speaker 1: So all these particles that were aware of, there's another
• 13:39
  Speaker 1: way they're reflected, not just like there's a heavier version
• 13:41
  Speaker 1: of them, but now there's like this opposite version of
• 13:44
  Speaker 1: them where we take all the charges, for example, and
• 13:47
  Speaker 1: we flip them, so the electron has charged minus one.
• 13:50
  Speaker 1: There's another version of the electron, which we call the
• 13:52
  Speaker 1: antimatter version of the electron. Sometimes we call it a positron,
• 13:57
  Speaker 1: which has charged plus one. So it's reflected in this
• 14:01
  Speaker 1: like different direction. And that's true also for the muan
• 14:04
  Speaker 1: and for the up cork, and for the down cork
• 14:06
  Speaker 1: and the top cork. All these particles have their antimatter versions.
• 14:10
  Speaker 1: So the antimatter versions are when you flip their charges,
• 14:15
  Speaker 1: which is related to the kind of force they feel, right,
• 14:18
  Speaker 1: Like electrons feel the electromagnetic force, which means they have
• 14:22
  Speaker 1: a charge, and that's what you flip to get the
• 14:24
  Speaker 1: anti electron exactly. And we're talking here just about the
• 14:27
  Speaker 1: electric charge, which is a label that we put on
• 14:30
  Speaker 1: particles that feel the electromagnetic force. And a minus charge
• 14:34
  Speaker 1: means one thing, and a positive charge means something else.
• 14:37
  Speaker 1: And we know, for example that like positive negative charges
• 14:40
  Speaker 1: will pull on each other and similar charges will repel
• 14:43
  Speaker 1: each other. So that's a label we put on particles
• 14:45
  Speaker 1: to describe how they react to electromagnetic fields. And so
• 14:49
  Speaker 1: an electron an apostitron are the same, except they react
• 14:52
  Speaker 1: oppositely to these fields. The same electromagnetic field which pushes
• 14:56
  Speaker 1: an electron up will push a positron down, so it
• 14:59
  Speaker 1: has the same mass as an electron, but the opposite
• 15:02
  Speaker 1: electric charge. Right. And then other particles like the corks,
• 15:06
  Speaker 1: they don't feel the electromagnetic force, right, so they don't
• 15:09
  Speaker 1: have electrical charge. Right. Corks do have electromagnetic charge, but
• 15:13
  Speaker 1: they're really weird. They're like plus two thirds or minus
• 15:16
  Speaker 1: one third, so they definitely feel electromagnetic fields. You just
• 15:20
  Speaker 1: don't typically think of them as doing so because they
• 15:22
  Speaker 1: also have a charge for a much more powerful force,
• 15:24
  Speaker 1: a strong nuclear force. So they have the electric charge
• 15:28
  Speaker 1: and they also have this color charge for the strong
• 15:31
  Speaker 1: nuclear force. Okay, so of course feel the color charge
• 15:34
  Speaker 1: and also the electric charge. Now, then is an anti
• 15:38
  Speaker 1: cork something that has both of those things flipped or
• 15:41
  Speaker 1: just one of those things flipped. Both of those things
• 15:43
  Speaker 1: get flipped for an antiquark exactly. And I guess that's
• 15:47
  Speaker 1: true for all the other particles. But what about the
• 15:49
  Speaker 1: force particles. That's also true for their antimatter versions, So
• 15:52
  Speaker 1: that's really interesting. It actually depends on the force particle.
• 15:56
  Speaker 1: So for example, the W boson that actually carries electric charge,
• 16:00
  Speaker 1: it's like there's a positive version and a negative version,
• 16:03
  Speaker 1: and one is the anti particle of the other. So
• 16:05
  Speaker 1: the antiparticle of the W plus is the W minus. Okay. Yeah.
• 16:09
  Speaker 1: And then there's some interesting things about certain particles that
• 16:12
  Speaker 1: are their own antiparticle, like photons, right, that's right. For photons,
• 16:16
  Speaker 1: there is no other particle to serve as the antiparticle.
• 16:19
  Speaker 1: They are their own antiparticle, which is sort of weird.
• 16:23
  Speaker 1: But the way we think about in particle physics is
• 16:25
  Speaker 1: like you take a particle, you apply the antiparticle operator
• 16:29
  Speaker 1: to it, and say, what do you get? If you
• 16:30
  Speaker 1: start with an electron and you apply the antimatter particle
• 16:33
  Speaker 1: operator to it, you get a positron. You start with
• 16:36
  Speaker 1: the photon and you apply this operator to it, you
• 16:39
  Speaker 1: just get the photon back and sort of like symmetric.
• 16:41
  Speaker 1: So the photon serves as its own antiparticle. Because I guess,
• 16:45
  Speaker 1: does the photon have a charge. Photon does not have
• 16:48
  Speaker 1: an electric charge, right, the photon does not feel electromagnetic fields.
• 16:51
  Speaker 1: If a photon is flying through space and this electric
• 16:54
  Speaker 1: field there does not bend the path of the photon.
• 16:57
  Speaker 1: If you don't have anything to flip, then you can't
• 16:59
  Speaker 1: have an antimatter because is that kind of generally the rule.
• 17:02
  Speaker 1: That's generally the rule, and that holds also for example,
• 17:04
  Speaker 1: for gluons. Luonto the particle that transmit the strong nuclear force,
• 17:08
  Speaker 1: and they do carry color, they carry this charge, and
• 17:12
  Speaker 1: so you can't have anti gluons. You can take a
• 17:14
  Speaker 1: gluon and make the anti version of it as the
• 17:17
  Speaker 1: opposite color. All right, So that's matter and antimatter. But
• 17:21
  Speaker 1: one thing, I guess all matters seems to have in common,
• 17:24
  Speaker 1: whether or not it feels certain forces or not. Is
• 17:27
  Speaker 1: that everybody seems to feel gravity? Right, Well, we're not
• 17:30
  Speaker 1: exactly sure about what happens with antimatter and gravity, but
• 17:33
  Speaker 1: there is something we think that isn't flipped, which is
• 17:35
  Speaker 1: the mass. Like an electron we think has the same
• 17:39
  Speaker 1: mass as a positron, it's not like that mass then
• 17:42
  Speaker 1: goes negative. That suggests they probably have a similar relationship
• 17:45
  Speaker 1: to gravity as the original particle, but we just aren't sure. Well, yeah,
• 17:49
  Speaker 1: I guess that's what I was trying to get at,
• 17:51
  Speaker 1: which is that a lot of most of these particles,
• 17:54
  Speaker 1: the matter particles, have mass, right, that's one thing we
• 17:56
  Speaker 1: know about them, and almost in a way, that's kind
• 17:58
  Speaker 1: of what makes the matter part Yeah, all the fermions
• 18:01
  Speaker 1: definitely do have mass. Even the new trinos have mass,
• 18:04
  Speaker 1: even though they have a really tiny little bit of it,
• 18:07
  Speaker 1: and all of them get mass, we think from the
• 18:09
  Speaker 1: same process, which is interacting with the Higgs boson, And
• 18:12
  Speaker 1: to interact with the Higgs boson you have to have
• 18:14
  Speaker 1: an antimatter particle. Also, the Higgs boson requires particles to
• 18:18
  Speaker 1: interact like in pairs. It couldn't give the electron mass
• 18:21
  Speaker 1: if the positron didn't exist, for example, right, All right,
• 18:24
  Speaker 1: well then, I guess you know, we know that all
• 18:27
  Speaker 1: of these matter particles feel gravity, right because we feel gravity,
• 18:31
  Speaker 1: and all of the things on Earth feel gravity. And
• 18:34
  Speaker 1: we know that the stars and the planets out there,
• 18:36
  Speaker 1: and the galaxies and the galaxy clusters all feel gravity
• 18:40
  Speaker 1: and they're mostly made out of matter stuff. And so
• 18:43
  Speaker 1: the question that is, does antimatter also feel gravity or
• 18:47
  Speaker 1: does it feel something else, maybe the opposite of gravity.
• 18:51
  Speaker 1: And so let's get into that weighty question. But first
• 18:55
  Speaker 1: let's take a quick break. All right, we're anti talking
• 19:11
  Speaker 1: about not feeling anti gravity or is this a pro
• 19:15
  Speaker 1: gravity podcast? I'm definitely pro gravity. I don't want it
• 19:18
  Speaker 1: to pick up and move somewhere else, like I'd like
• 19:19
  Speaker 1: for it to stay pretty much where it is. I'm
• 19:22
  Speaker 1: relying on it every day. Oh really, I guess I'm
• 19:24
  Speaker 1: more morally flexible when it comes to gravity. I mean,
• 19:27
  Speaker 1: if I could, like, you know, ignore it for a
• 19:29
  Speaker 1: little bit, that'd be pretty cool to fly around, wouldn't
• 19:32
  Speaker 1: that be great? It would be nice to be able
• 19:34
  Speaker 1: to manipulate gravity, right If we had ways to create
• 19:36
  Speaker 1: like anti gravity somehow, it'd be easier to move your
• 19:40
  Speaker 1: bed across the room, or to ship stuff across the world,
• 19:43
  Speaker 1: or to launch stuff into outer space. That would be
• 19:46
  Speaker 1: pretty awesome. We forget other stuff. How about ourselves, we
• 19:49
  Speaker 1: could all be flying around. Finally, you get that flying
• 19:54
  Speaker 1: car exactly right. It could be an anti car. Well,
• 19:58
  Speaker 1: that's one of the exciting things about all of these
• 20:00
  Speaker 1: open questions is that once you understand the way the
• 20:03
  Speaker 1: universe works, you might discover something really surprising that's could
• 20:06
  Speaker 1: give you a handle for creating all sorts of new
• 20:09
  Speaker 1: crazy technologies. Yeah. I mean, we've been waiting for these
• 20:12
  Speaker 1: anti gravity flying cars for for years. We're still waiting, Daniel,
• 20:15
  Speaker 1: what's the hold? Well, you know, antime matter is not
• 20:20
  Speaker 1: easy to study. It's sort of all around us in
• 20:23
  Speaker 1: very very tiny amounts. It's made when cosmic rays hit
• 20:27
  Speaker 1: the atmosphere. Part of the shower of particles that comes
• 20:29
  Speaker 1: down to the surface is antimatter. There's like muans and
• 20:33
  Speaker 1: anti muans as well, but it doesn't last very long
• 20:36
  Speaker 1: because it smashes into stuff and annihilates, and it just
• 20:39
  Speaker 1: doesn't seem to be very much of it in the universe,
• 20:42
  Speaker 1: which is one of the big mysteries. Right. We talked
• 20:44
  Speaker 1: a lot about how matter and antimatter are symmetric. It's
• 20:47
  Speaker 1: all the same, just with the flipped number. You might
• 20:49
  Speaker 1: wonder like, well, why isn't there more antimatter in the universe.
• 20:53
  Speaker 1: Why is the universe matter and not anti matter? What's
• 20:56
  Speaker 1: the difference in the end. Yeah, we have a whole
• 20:58
  Speaker 1: episode on that, and I think we also have a
• 21:00
  Speaker 1: whole episode on the annihilation of matter and antimatter. Right.
• 21:03
  Speaker 1: When a matter particle like an electron hits it's antimatter
• 21:07
  Speaker 1: version a positron, they like disappear and turn into pure energy, right, Yeah,
• 21:11
  Speaker 1: they can turn into a photon, they can turn into
• 21:13
  Speaker 1: a z boson, And you're right, they do disappear, right.
• 21:16
  Speaker 1: It's not like what comes out as a rearrangement of
• 21:19
  Speaker 1: the bits inside the electron and the positron. This really
• 21:22
  Speaker 1: is alchemy that we're talking about. You're transforming the energy
• 21:25
  Speaker 1: from one quantum field the electron of depositron field, then
• 21:29
  Speaker 1: into a photon field, and then into something else. That
• 21:32
  Speaker 1: photon can turn into corks or into w's or into
• 21:36
  Speaker 1: something else entirely. It really is pretty awesome. This annihilation
• 21:39
  Speaker 1: is like a conduit for transforming matter into something else.
• 21:43
  Speaker 1: And it's funny that you mentioned that it's all around us, right,
• 21:46
  Speaker 1: I mean, well, technically it is all around us, because
• 21:48
  Speaker 1: if there's an electron quantum field all around this, there's
• 21:51
  Speaker 1: also an anti electron quantum field all around this too. Right.
• 21:55
  Speaker 1: Is it a separate field or is it the same
• 21:56
  Speaker 1: field as the electron? Oh, good question, It is its
• 21:59
  Speaker 1: own field. There's another field there for the anti electron.
• 22:03
  Speaker 1: We tend to comple them together sometimes in the calculations,
• 22:06
  Speaker 1: although it gets complicated because there's like left handed versions
• 22:10
  Speaker 1: of them and right handed versions of them, and the
• 22:11
  Speaker 1: weak force treats those differently. Dig into our episode about
• 22:14
  Speaker 1: the weak force and symmetry to understand that more in detail.
• 22:18
  Speaker 1: But the short answer is, yes, we are surrounded by
• 22:20
  Speaker 1: quantum fields for antiparticles. Even if there aren't actually antiparticles
• 22:25
  Speaker 1: around us. Their fields are there, like parking spots are
• 22:28
  Speaker 1: there even if no cars are in them. Yeah, there's
• 22:30
  Speaker 1: negativity all around us these days, it seems. But as
• 22:33
  Speaker 1: we're saying, what's interesting about antimatter is that it's like
• 22:36
  Speaker 1: regular matter, but it has certain of its properties flipped,
• 22:40
  Speaker 1: like the charge of the electromagnetic force and charge and
• 22:43
  Speaker 1: also it's a color and things like that. And so
• 22:46
  Speaker 1: one thing that regular matter particles we know have is
• 22:49
  Speaker 1: something called mass, Like it's a little it's a property
• 22:52
  Speaker 1: of regular matter particles, and that's the thing that gives it,
• 22:56
  Speaker 1: you know, inertia, and it makes it feel gravity. Right,
• 22:58
  Speaker 1: it's kind of a measure of how much it feels
• 23:00
  Speaker 1: gravity or how hard it is to push or pull. Yeah,
• 23:03
  Speaker 1: mass is one of these amazing things that seems so simple.
• 23:06
  Speaker 1: We think we understand it. You have an intuitive stance
• 23:08
  Speaker 1: of what mass is, but when you dig into it theoretically,
• 23:11
  Speaker 1: it turns out to be kind of complicated. As you
• 23:14
  Speaker 1: say this, two different ideas of mass there. One is
• 23:17
  Speaker 1: inertial mass, which is like, when you push on something,
• 23:20
  Speaker 1: how much does it move? And that's the mass that
• 23:23
  Speaker 1: appears in Newton's equation F equals M A. Basically, it
• 23:27
  Speaker 1: relates F how hard you're pushing on something to A
• 23:30
  Speaker 1: how fast it accelerates when you push on it. And
• 23:33
  Speaker 1: Newton tells us that the relationship between those two quantities
• 23:35
  Speaker 1: is mass. That's sort of what inertial mass is. Something
• 23:39
  Speaker 1: with more inertial mass takes a larger force to get
• 23:42
  Speaker 1: the same acceleration. Something with almost no inertial mass. You
• 23:45
  Speaker 1: can accelerate pretty easily with a very small force. That's
• 23:49
  Speaker 1: conceptionally different from this other concept of mass, gravitational mass.
• 23:54
  Speaker 1: That's the mass that appears, and like the gravitational force
• 23:56
  Speaker 1: equation g mm over are squared that tells you, like
• 24:01
  Speaker 1: how strong gravitational forces between two objects, right, and so,
• 24:05
  Speaker 1: regular particles have this property that we call mass. I
• 24:08
  Speaker 1: mean we've called it before in this podcast. Like it's
• 24:10
  Speaker 1: almost like a label or it's almost like a charge
• 24:13
  Speaker 1: for the force of gravity, right, Like the electric charge
• 24:16
  Speaker 1: is kind of like it's a measure how much it
• 24:18
  Speaker 1: feels electromagnetic force. Mass is kind of like the measure
• 24:22
  Speaker 1: of how much it feels gravity and inertiap Right, It's
• 24:24
  Speaker 1: almost like it's like a little property of matter. Yeah,
• 24:27
  Speaker 1: it's like a little property of matter and you shouldn't
• 24:29
  Speaker 1: think of it. It's like how much stuff the electron has,
• 24:32
  Speaker 1: or how much stuff the top cork has. In our theory,
• 24:35
  Speaker 1: these are all point particles. I have no volume. This
• 24:38
  Speaker 1: is just like a property of the particle. If you're
• 24:40
  Speaker 1: comfortable assigning like quantum labels to things, like this thing
• 24:44
  Speaker 1: has a positive charge, and you don't have to like
• 24:47
  Speaker 1: figure out a physical place for that charge to live.
• 24:50
  Speaker 1: You should try to do the same thing with the
• 24:52
  Speaker 1: mass of the particle. Like the particle just has this mass.
• 24:55
  Speaker 1: You don't have to like have room to put enough
• 24:57
  Speaker 1: stuff into the top cork to make heavy. It just
• 25:01
  Speaker 1: sort of is that massive. There's another interesting level to
• 25:04
  Speaker 1: dig into there, which is like, is this mass actually
• 25:07
  Speaker 1: a property of the particle itself or is it a
• 25:10
  Speaker 1: property of the interaction of that particle with fields, Because
• 25:14
  Speaker 1: we think that like in a universe without a Higgs field,
• 25:17
  Speaker 1: all these matter particles, the top cork, the electron, they
• 25:19
  Speaker 1: would be massless, they would fly around like photons. It's
• 25:23
  Speaker 1: only because the Higgs field is there that these particles
• 25:26
  Speaker 1: have a mass. So sort of like a cloud of
• 25:28
  Speaker 1: Higgs bosons surrounding every particle changing the way it moves
• 25:32
  Speaker 1: so that it looks like as if it had mass.
• 25:34
  Speaker 1: So if you want to zoom out, you can just think,
• 25:36
  Speaker 1: I'm just gonna put a label on these particles. You
• 25:38
  Speaker 1: want to zoom in, you could think about, like, well,
• 25:41
  Speaker 1: this particle is sort of like a virtual cloud of
• 25:43
  Speaker 1: Higgs bosons around it that are changing it, and I'm
• 25:46
  Speaker 1: just going to label the whole cloud is having this mass.
• 25:49
  Speaker 1: Do you think of it as a kind of a
• 25:50
  Speaker 1: label like you said that particles just have just like
• 25:53
  Speaker 1: electric charge, And so the question is if antimatter is
• 25:57
  Speaker 1: just regular matter with some of the charges flipped, does
• 26:00
  Speaker 1: it also flip the label of mass, like does it
• 26:04
  Speaker 1: also flip how it feels gravity or how it feels inertia? Right,
• 26:07
  Speaker 1: that's the main question we're asking today. Yeah, and it
• 26:09
  Speaker 1: really comes down to this basic question about what is
• 26:12
  Speaker 1: gravity anyway? Is gravity a force the way the other
• 26:16
  Speaker 1: forces are, you know, the electromagnetic force and the strong force,
• 26:20
  Speaker 1: who have all their charges flipped for antimatter. If you
• 26:23
  Speaker 1: think about it that way, then gravity is just another
• 26:25
  Speaker 1: force and the charge for it is mass, as you say,
• 26:28
  Speaker 1: And then it would make sense. It would be like
• 26:30
  Speaker 1: sementric It would follow the pattern if also mass was
• 26:33
  Speaker 1: flipped for antimatter. Or is gravity not a force? If
• 26:37
  Speaker 1: gravity is something else? And we've been thinking about it
• 26:40
  Speaker 1: as a force because we just don't see the curvature
• 26:43
  Speaker 1: of space and time, and so we've created this fictitious
• 26:46
  Speaker 1: force to explain the effect of the bending of space
• 26:49
  Speaker 1: time on the motion of particles and If that's the case,
• 26:52
  Speaker 1: it would make sense for space time to treat everything
• 26:55
  Speaker 1: inside of it the same way. Antimatter and matter particles
• 26:58
  Speaker 1: are both just little bundles of energy and his energy
• 27:00
  Speaker 1: that bends that space, and so then it would make
• 27:03
  Speaker 1: sense for matter and antimatter to all have the same
• 27:05
  Speaker 1: relationship with gravity instead of the opposite relationship. So this
• 27:09
  Speaker 1: question about whether antimatter feels gravity or anti gravity is
• 27:13
  Speaker 1: also kind of a question about like what is gravity anyway?
• 27:16
  Speaker 1: But I guess the main picture of trying to pain
• 27:18
  Speaker 1: is that you know, like if an electron has a
• 27:21
  Speaker 1: negative charge, the negative electric charge, and it weighs, you know,
• 27:25
  Speaker 1: point zero zero zero zero zero something kilograms, doesn't anti
• 27:29
  Speaker 1: electron not just have positive electric charge, but does it
• 27:33
  Speaker 1: also maybe way negative through a point zero zeros there
• 27:37
  Speaker 1: zero something kilograms? And what would that mean for the
• 27:40
  Speaker 1: anti electron? Yeah, that would be super fascinating, right, And
• 27:44
  Speaker 1: because we have two different concepts of mass, we have
• 27:47
  Speaker 1: to think about them sort of individually. Like if a
• 27:49
  Speaker 1: positron had negative inertial mass, what would that mean? It
• 27:54
  Speaker 1: would mean that if you push on it in one direction,
• 27:58
  Speaker 1: it would accelerate the other direction, right, Remember force equals
• 28:02
  Speaker 1: mass times acceleration. These are vectors, So if mass is negative,
• 28:07
  Speaker 1: that means that acceleration of force are pointing in different directions.
• 28:10
  Speaker 1: So you like give it a shove to the left
• 28:12
  Speaker 1: and it moves to the right. That's what having negative
• 28:15
  Speaker 1: inertial mass would mean. That's like really counterintuitive. Negative gravitational
• 28:20
  Speaker 1: mass would be different. It would allow for gravitational repulsion.
• 28:24
  Speaker 1: Gravity attracts things that both have positive mass. But if
• 28:28
  Speaker 1: two particles, one with positive gravitational mass and one with
• 28:31
  Speaker 1: negative gravitational mass meat, they might repel each other, which
• 28:35
  Speaker 1: would be really interesting because that's not something we've ever seen.
• 28:38
  Speaker 1: Gravitational repulsion. Yeah, super fascinating. And so let's maybe talk
• 28:43
  Speaker 1: more about each of these scenarios one at a time.
• 28:45
  Speaker 1: And so, first of all, let's say that antimatter doesn't
• 28:48
  Speaker 1: just flip the charges electrical charges of the forces in
• 28:52
  Speaker 1: regular matter particles, but let's say it also flips its
• 28:54
  Speaker 1: inertial mass, so it has anti inertia. I guess is
• 28:58
  Speaker 1: the idea, And like you said, it's kind of kind
• 29:01
  Speaker 1: of intuitive where you try to push something but it
• 29:03
  Speaker 1: actually moves towards you. That would be weird, right, That
• 29:07
  Speaker 1: would be very weird instead of counter through everything we've
• 29:10
  Speaker 1: understood and everything we've experienced in the universe, that would
• 29:14
  Speaker 1: be a very strange experience for us to shove somebody
• 29:16
  Speaker 1: and then have them slam into you. But I guess
• 29:18
  Speaker 1: maybe it does make sense if you just think about
• 29:21
  Speaker 1: it as it being antimatter, and where you think you're
• 29:25
  Speaker 1: pushing it, you're actually pulling it because it feels you're
• 29:27
  Speaker 1: pushing force the opposite way, So it's almost like you're
• 29:31
  Speaker 1: just pulling on something, right, Like an electron attracts a
• 29:35
  Speaker 1: positively charged particle, right, so it doesn't push it when
• 29:38
  Speaker 1: it gets near it, it actually pulls it. So couldn't
• 29:41
  Speaker 1: that just be the same for anti mass? It could be,
• 29:44
  Speaker 1: although it's a bit more general than that. We're talking about.
• 29:46
  Speaker 1: Any force applied to a positron would then move it
• 29:50
  Speaker 1: in the opposite direction of that force, whether it's a
• 29:53
  Speaker 1: gravitational force or electromagnetic force, or the weak force, which
• 29:57
  Speaker 1: positrons also feel. It's a little bit deeper than just
• 30:00
  Speaker 1: saying electromagnetism can attract and repel, so what's the big deal.
• 30:03
  Speaker 1: Now it's applied to every force on this positron, it
• 30:07
  Speaker 1: would be pretty strange. Yeah, but I mean if you
• 30:09
  Speaker 1: think about it, like an electron repels another electron, right,
• 30:13
  Speaker 1: because they have both have negative charge. Now, if you
• 30:16
  Speaker 1: have an electron and a positron, they would normally attract
• 30:20
  Speaker 1: each other because they have opposite charges. But then if
• 30:23
  Speaker 1: it has negative inertial mass, then it actually maybe flips
• 30:26
  Speaker 1: that force and it does repel. Yeah. I think what
• 30:28
  Speaker 1: happens there is even weirder because the positron is repelled
• 30:32
  Speaker 1: from the electron, but the electron is still attracted to
• 30:36
  Speaker 1: the positron, right, It's still attracted to that positive charge,
• 30:39
  Speaker 1: and so they sort of like chase each other. Like
• 30:42
  Speaker 1: the positron gets pushed away from the electron, but the
• 30:44
  Speaker 1: electron gets pulled along with the positron, So you get
• 30:48
  Speaker 1: this sort of like weird runaway effect. Yeah. I guess
• 30:50
  Speaker 1: when that is kind of a way to prove that
• 30:53
  Speaker 1: antimatter doesn't have anti inertial mass is that, you know,
• 30:57
  Speaker 1: if you have an electron, it gets attracted to an
• 31:00
  Speaker 1: anti electron, which means that it doesn't have anti inertia. Yeah,
• 31:04
  Speaker 1: anti inertia would be really weird. Negative inertial mass particles
• 31:08
  Speaker 1: would behave very strangely, and this is something we would
• 31:11
  Speaker 1: have seen because we do see positrons in the world.
• 31:14
  Speaker 1: We see them in cosmic rays, we can bend them
• 31:16
  Speaker 1: with magnets. We don't see them doing this sort of
• 31:19
  Speaker 1: weird behavior of being pushed in the opposite direction of
• 31:23
  Speaker 1: the force. So negative inertial mass is not something anybody
• 31:25
  Speaker 1: really considers seriously. When it comes to antimatter. It would
• 31:28
  Speaker 1: be really bizarre. We haven't seen it, but I wonder
• 31:30
  Speaker 1: if it's possible, Like could you have maybe a third
• 31:34
  Speaker 1: version of an electron, not just a positron, with something
• 31:38
  Speaker 1: that has its opposite charge, but also has negative inertia,
• 31:44
  Speaker 1: which would act just like another electron to an electron,
• 31:47
  Speaker 1: Like you would think it was an electron, but really
• 31:49
  Speaker 1: it's an antimatter electron with a flip inertial mass. Yeah,
• 31:56
  Speaker 1: negative mass electron. It's certainly possible that there are other
• 31:59
  Speaker 1: reflect actions of the particles that we're not aware of.
• 32:02
  Speaker 1: Our we're not limited to just matter and antimatter or
• 32:05
  Speaker 1: heavier versions. You know, there are theories about like supersymmetric
• 32:08
  Speaker 1: versions of each of these particles, and so it's totally
• 32:11
  Speaker 1: possible to come up with another idea like a particle
• 32:14
  Speaker 1: that it's just like the electron, but with negative inertial mass,
• 32:16
  Speaker 1: and say maybe it could exist in the universe. Then
• 32:19
  Speaker 1: you have to answer questions like, well, why was made
• 32:21
  Speaker 1: in the Big Bang? Where are these? If they do exist,
• 32:25
  Speaker 1: why haven't we seen them? And if you haven't seen them,
• 32:27
  Speaker 1: they have to come up with an explanation for why
• 32:29
  Speaker 1: they don't seem to appear in our universe. But it
• 32:32
  Speaker 1: doesn't mean that it couldn't possibly exist in the universe.
• 32:35
  Speaker 1: But I guess you're saying that the antimatter that we
• 32:38
  Speaker 1: have seen so far, like the anti electrons that we've seen,
• 32:41
  Speaker 1: seem to have regular inertial mass. Yeah, and this is
• 32:44
  Speaker 1: not so challenging to observe because we can apply pretty
• 32:47
  Speaker 1: powerful forces like electromagnetic forces to antimatter particles, which are
• 32:51
  Speaker 1: rare but not impossible to make into manipulated and we
• 32:54
  Speaker 1: can see their behavior. So, for example, the discovery of
• 32:57
  Speaker 1: antimatter was seeing a positron moved through a magnetic field
• 33:02
  Speaker 1: and bending in a way that an electron doesn't. So
• 33:05
  Speaker 1: we're pretty sure that antimatter has inertial mass the same
• 33:08
  Speaker 1: way that normal matter does. All right, Well, now let's
• 33:11
  Speaker 1: tackle this idea of having anti gravitational mass. Now, is
• 33:15
  Speaker 1: there such a thing as gravitational mass? I thought gravity
• 33:18
  Speaker 1: wasn't really a force, It was really kind of a
• 33:20
  Speaker 1: bending of space. This idea has some interesting history. Newton
• 33:24
  Speaker 1: considered these things separate. He said, things have inertial mass
• 33:27
  Speaker 1: and they have gravitational mass. These are different ideas. If
• 33:29
  Speaker 1: you're on an empty space where there's no gravity, and
• 33:31
  Speaker 1: objects still had inertia, right, and the force of gravity,
• 33:35
  Speaker 1: the mass that appears in there didn't necessarily have to
• 33:38
  Speaker 1: be the same as the mass in F equals m A.
• 33:40
  Speaker 1: People measured it, and they always found these two things
• 33:43
  Speaker 1: to be the same. The mass that appears in those
• 33:45
  Speaker 1: equations were the same, and so people thought, well, that's weird,
• 33:48
  Speaker 1: what a crazy coincidence of these things really are separate
• 33:50
  Speaker 1: concepts and yet always managed to be exactly the same.
• 33:53
  Speaker 1: So that was sort of an unexplained mystery for a
• 33:55
  Speaker 1: long time. Einstein, when he developed his theory of relativity,
• 33:59
  Speaker 1: he said, well, let's just assume that these things are
• 34:01
  Speaker 1: the same. He baked that in to his theory of relativity.
• 34:05
  Speaker 1: That's not a proof that they are, that's just an
• 34:07
  Speaker 1: assumption of the foundation of general relativity. He said that
• 34:11
  Speaker 1: gravity and inertia are basically the same thing. Okay, and
• 34:15
  Speaker 1: so then what does that mean for having negative gravitational
• 34:18
  Speaker 1: mass or anti gravitational mass. Well, it means that general
• 34:21
  Speaker 1: relativity makes a very strong prediction that anything with energy
• 34:25
  Speaker 1: bends space the same way. And so we think that
• 34:28
  Speaker 1: antimatter probably feels gravity the same way that matter does.
• 34:33
  Speaker 1: So Einstein and general relativity say antimatterer should feel gravity,
• 34:37
  Speaker 1: it shouldn't feel anti gravity, and that's a strong prediction
• 34:40
  Speaker 1: from general relativity. Well, that's a strong you're saying assumption
• 34:43
  Speaker 1: about general relativity, right, But it is it possible for
• 34:46
  Speaker 1: something to have negative gravitational mass, so that if I
• 34:50
  Speaker 1: throw it at a black hole, it's actually going to
• 34:51
  Speaker 1: run away from the black hole and not towards the
• 34:53
  Speaker 1: black hole. I mean, it's possible in the sense that
• 34:56
  Speaker 1: like anything is possible in the universe, and we don't
• 34:58
  Speaker 1: know if general relativity accurately describes everything in the universe,
• 35:03
  Speaker 1: and specifically, we don't know how to apply general relativity
• 35:05
  Speaker 1: to particles. So it's possible that antimatter breaks general relativity
• 35:10
  Speaker 1: and that quantum gravity allows for other weird forces on
• 35:14
  Speaker 1: antimatter particles like anti gravity. But if you just say
• 35:18
  Speaker 1: we believe in general relativity, then it's not possible for
• 35:21
  Speaker 1: antimatter to have anti gravity. I see, So if something
• 35:25
  Speaker 1: could have negative gravitational mass, it would mean Einstein was wrong,
• 35:30
  Speaker 1: or that general grotivity needs to be maybe expanded. Doesn't
• 35:33
  Speaker 1: necessarily mean it's wrong, or would you just need to
• 35:36
  Speaker 1: like add something to Einstein's theory. Well, that's an interesting
• 35:38
  Speaker 1: philosophical question. I mean, we're pretty sure that Einstein is wrong,
• 35:43
  Speaker 1: not in the sense that any of his predictions have
• 35:45
  Speaker 1: been proven wrong, but we don't know how to extend
• 35:47
  Speaker 1: his theory to quantum particles. It definitely needs some sort
• 35:50
  Speaker 1: of adaptation, and that might mean that it needs to
• 35:53
  Speaker 1: be like tossed out and completely replaced with the theory
• 35:55
  Speaker 1: of quantum gravity. That's a completely different picture of how
• 35:58
  Speaker 1: space gets bent using like quantum gravitons. Or it might
• 36:02
  Speaker 1: be that we take Einstein's theory and we quantize it
• 36:05
  Speaker 1: that we like say, space itself is made of quantum
• 36:08
  Speaker 1: bits that are woven together, and general relativity emerges from that.
• 36:11
  Speaker 1: We really don't know whether we need to build on
• 36:13
  Speaker 1: top of Einstein's theory or whether we need to like
• 36:15
  Speaker 1: re examine the very foundations of it. But we do
• 36:18
  Speaker 1: know that can't work in the quantum realm, so it
• 36:21
  Speaker 1: needs some sort of update. It might be that we
• 36:23
  Speaker 1: discovered failing only when we see inside black holes, or
• 36:26
  Speaker 1: it might be that we discovered failing when we examine
• 36:29
  Speaker 1: the gravitational properties of antimatter. Well, I guess I'm not
• 36:32
  Speaker 1: quite sure what you're saying. Are you saying that? Okay?
• 36:34
  Speaker 1: So eince science theory assumes that gravitational mass and inertial
• 36:38
  Speaker 1: mass are the same, which means that you can't have
• 36:42
  Speaker 1: negative rotational mass anti gravitational mass, or that you still
• 36:46
  Speaker 1: could or like, if you have negative inertial math anti
• 36:49
  Speaker 1: inertial mass, then that would also mean you have anti
• 36:52
  Speaker 1: gravity irrotational mass. Einstein's theory says you can't have negative
• 36:56
  Speaker 1: gravitational mass, that that just can't happen because of the
• 36:59
  Speaker 1: equip into principle. But we don't know that that's true, right,
• 37:02
  Speaker 1: We don't know what the universe actually does. So if
• 37:05
  Speaker 1: we discover antimatter with negative gravitational mass, that means general
• 37:10
  Speaker 1: relativity is wrong in some important way. But maybe wouldn't
• 37:13
  Speaker 1: that just mean that it has negative inertial mass. Like,
• 37:16
  Speaker 1: if something has a negative inertial in them mass, then
• 37:18
  Speaker 1: in in Einstein's formulation, they would also have negative gravitational mass. Yeah,
• 37:23
  Speaker 1: that's a really cool thought. You're right that general relativity
• 37:25
  Speaker 1: just requires that they have the same inertial and gravitational mass,
• 37:30
  Speaker 1: which I suppose would allow for them to both be negative.
• 37:33
  Speaker 1: But again, we haven't seen particles with negative inertial mass.
• 37:36
  Speaker 1: So the antimatter we know and we are familiar with
• 37:39
  Speaker 1: doesn't have negative inertial mass, so then general relativity would
• 37:43
  Speaker 1: predict that it also has positive gravitational mass M. So
• 37:47
  Speaker 1: it's then it is possible to have a particle out
• 37:49
  Speaker 1: there that if you throw at a black hole, it's
• 37:51
  Speaker 1: going to run away from the black hole. But if
• 37:53
  Speaker 1: it has both negative and gravitational mass, it would have
• 37:57
  Speaker 1: the opposite force on it, and then that worse would
• 38:00
  Speaker 1: push it in the opposite direction, and two opposites resulted
• 38:03
  Speaker 1: in going the same way. WHOA, So it would still
• 38:08
  Speaker 1: go towards the black hole. It would still go towards
• 38:10
  Speaker 1: the black hole, Yes, because they would cancel each other out. Yeah, exactly.
• 38:14
  Speaker 1: Black hole's force would technically be away from it, and
• 38:17
  Speaker 1: that would result in a particle moving towards it. So
• 38:20
  Speaker 1: double bonkers unless um, somehow Einstein's theory is wrong and
• 38:25
  Speaker 1: they're sort of not the same thing, right exactly, the
• 38:27
  Speaker 1: possibility that Einstein is wrong and that antimatter particles have
• 38:31
  Speaker 1: positive inertial mass and negative gravitational mass. All right, well,
• 38:35
  Speaker 1: it seems like, um, it is possible maybe to have
• 38:38
  Speaker 1: anti gravity from being an antimatter particle, to have an
• 38:42
  Speaker 1: anti inertial or anti gravitational mass seems possible. But I
• 38:47
  Speaker 1: guess then the question is does it actually happen? What
• 38:50
  Speaker 1: are some experiments we've done to try to find the
• 38:53
  Speaker 1: answer to this question. So let's get into that, But
• 38:55
  Speaker 1: first let's take another quick break. All right, we are
• 39:11
  Speaker 1: feeling a lot of anti emotions here talking about antimatter,
• 39:15
  Speaker 1: anti gravity, anti mass, anti everything. It's a very contrary episode.
• 39:22
  Speaker 1: We're going up, we're going down. We're going anti up
• 39:24
  Speaker 1: and anti down all at the same time. Can you
• 39:26
  Speaker 1: go anti anti? Those would be your double negative mass particles, right,
• 39:32
  Speaker 1: be anti anti attracted to a black hole? What would
• 39:36
  Speaker 1: you call the antimatter version of your parents, sister, your
• 39:39
  Speaker 1: anti anti These are tough questions we're asking today, assuming
• 39:44
  Speaker 1: people are still listening or the left in an anti huff.
• 39:48
  Speaker 1: All right, we're talking about whether or not antimatter feels
• 39:52
  Speaker 1: anti gravity, which is kind of turned out to be
• 39:54
  Speaker 1: a pretty complicated question because, first of all, you have
• 39:57
  Speaker 1: to think about whether antimatter has anti inertia mass or
• 40:00
  Speaker 1: anti gravitational mass, and whether or not if they're the
• 40:03
  Speaker 1: same thing according to Einstein, or maybe they're not. I
• 40:05
  Speaker 1: don't know. I don't know. I feel like from all
• 40:07
  Speaker 1: this theoretical discussion, it seems like you're saying that it's
• 40:11
  Speaker 1: not possible to have anti gravity. I think it's very
• 40:14
  Speaker 1: unlikely that antimatter has anti gravity just because general relativity
• 40:19
  Speaker 1: is so successful. The YadA YadA YadA, dot dot dot.
• 40:22
  Speaker 1: On the other hand, why do we do experiments. We
• 40:25
  Speaker 1: don't do experiments just to like yawn and check the
• 40:27
  Speaker 1: boxes off of theoretical predictions. We do experiments because we
• 40:31
  Speaker 1: want to explore the universe. We want to find crazy,
• 40:35
  Speaker 1: shocking things that we can't explain that let us pull
• 40:38
  Speaker 1: the rug out of everything we thought we knew and
• 40:40
  Speaker 1: build up new ideas about the universe. So this is
• 40:43
  Speaker 1: definitely something we should check. We should go and see
• 40:45
  Speaker 1: whether antimatter follows our expectations or anti follows them. I
• 40:50
  Speaker 1: think I see what you're saying. You're saying you're anti
• 40:52
  Speaker 1: anti gravity, but you're pro the government giving you more
• 40:56
  Speaker 1: money to run experiments. Is that kind of what I'm
• 40:58
  Speaker 1: sensing here. I it's a little um contradictory position here.
• 41:03
  Speaker 1: I think it's just exciting to go out and ask
• 41:05
  Speaker 1: basic questions, like, hey, does antimatter of f all up
• 41:08
  Speaker 1: or down? And it's incredible to me that almost a
• 41:11
  Speaker 1: hundred years after we've discovered anti matter, we still don't
• 41:14
  Speaker 1: really know the answer to that. Like, experimentally, it turned
• 41:17
  Speaker 1: out to be surprisingly tricky to do experiments with antimatter, right,
• 41:22
  Speaker 1: And specifically, you're talking about measuring I guess, the gravity
• 41:25
  Speaker 1: of a particle, right, I mean, you can measure the
• 41:27
  Speaker 1: gravity of a planet, of a person, of a banana,
• 41:29
  Speaker 1: but it's hard to kind of talk about the gravity
• 41:32
  Speaker 1: of tiny little particles because they feel very little gravity.
• 41:35
  Speaker 1: It's hard to even measure the gravity of a banana.
• 41:38
  Speaker 1: Like you can measure the weight of a banana, you
• 41:40
  Speaker 1: put it on a scale, but there you're measuring the
• 41:42
  Speaker 1: gravity of the Earth. Right. The Earth is pulling on
• 41:45
  Speaker 1: the banana. If you have two bananas in the room
• 41:47
  Speaker 1: next to you, it's pretty hard to measure their attraction
• 41:49
  Speaker 1: between themselves because gravity is so weak. It's like ten
• 41:54
  Speaker 1: to the thirty times as weak as electromagnetism, So it's
• 41:58
  Speaker 1: something we typically ignore. Right, you have two bananas on
• 42:01
  Speaker 1: your table, you don't expect to see them like creep
• 42:03
  Speaker 1: towards each other if you leave them alone. But they
• 42:06
  Speaker 1: would in space, Right, that's the idea. If you were
• 42:08
  Speaker 1: floating out there in space and you have two bananas,
• 42:10
  Speaker 1: eventually they would become a bi banana. Banana na na. Yeah.
• 42:15
  Speaker 1: But even doing that experiment in space would be hard
• 42:17
  Speaker 1: because the gravity is so weak that it might get
• 42:19
  Speaker 1: swamped by other stuff like the solar wind would probably
• 42:23
  Speaker 1: blow on those bananas, pushing on them harder than the
• 42:26
  Speaker 1: force of gravity between the bananas. Or if the bananas
• 42:29
  Speaker 1: have like a little bit of residual positive and negative charge,
• 42:32
  Speaker 1: like you rubbed one on your pants accidentally and giving
• 42:34
  Speaker 1: it some static electricity, then those forces, even a few
• 42:38
  Speaker 1: electrons on the surface of each one, would be more
• 42:40
  Speaker 1: powerful than gravity. So gravity is super hard to measure
• 42:44
  Speaker 1: for small things because it's so weak, it's swamped by
• 42:47
  Speaker 1: everything else. It's like trying to listen to a whisper
• 42:50
  Speaker 1: during a really loud concert. But I guess if you
• 42:53
  Speaker 1: said the experiment the right way and make sure everything
• 42:56
  Speaker 1: doesn't have a charge, the two bananas would come together eventually,
• 43:00
  Speaker 1: because that is what happens out there in space, right,
• 43:02
  Speaker 1: That's how planets get formed and asteroids and the sun. Right. Yeah,
• 43:05
  Speaker 1: we think that's the basic process for forming all of
• 43:08
  Speaker 1: the structure in the universe. And we've done some really
• 43:11
  Speaker 1: pretty awesome virtuoso experiments measuring the gravity of like little things,
• 43:16
  Speaker 1: things about the size of a centimeter and involves isolating
• 43:19
  Speaker 1: them from everything else and seeing very very small motion,
• 43:22
  Speaker 1: which people observe by like attaching a mirror to the
• 43:24
  Speaker 1: object and shining a laser on the mirror and seeing
• 43:27
  Speaker 1: the laser spot like move a tiny little bit so
• 43:30
  Speaker 1: that you see that the object has moved. These are
• 43:33
  Speaker 1: really super precise experiments, very very difficult to do, but
• 43:36
  Speaker 1: still there. With macroscopic objects, we're talking about like things
• 43:39
  Speaker 1: the size of a millimeter or centimeter, not individual particles,
• 43:42
  Speaker 1: so we can measure the mass of tiny, regular matter
• 43:47
  Speaker 1: of things. But I guess it's hard to do it
• 43:49
  Speaker 1: with antimatter, right, because that's really the question we're asking
• 43:52
  Speaker 1: today is like, if you have something made out of
• 43:54
  Speaker 1: or a whole bunch of antimatter in one spot, would
• 43:56
  Speaker 1: it feel anti gravity? That's the experiment. That's also hard
• 43:59
  Speaker 1: to do it because it's hard to put together a
• 44:01
  Speaker 1: lot of antimatter. It is. We can make antimatter at CERN,
• 44:04
  Speaker 1: for example, we smash matter into targets and the whole
• 44:07
  Speaker 1: spray of stuff comes out, including some antimatter, and we
• 44:10
  Speaker 1: can filter it out and do experiments with it, and
• 44:13
  Speaker 1: we do that kind of thing. But we make like
• 44:15
  Speaker 1: pico grams of antimatter every year it's CERN. So you
• 44:18
  Speaker 1: want to make like a bananas amount of antimatter, it
• 44:21
  Speaker 1: would cost zillions of dollars and take years and years
• 44:24
  Speaker 1: and years. So instead of making really big objects out
• 44:27
  Speaker 1: of antimatter, we try to do really precision experiments with
• 44:30
  Speaker 1: much smaller amounts of antimatter. Also, would be super dangerous
• 44:34
  Speaker 1: to come to make like a even a piece size
• 44:36
  Speaker 1: or raisin size amount of antimatter, because then if it
• 44:40
  Speaker 1: touches regular matter, it's it's going to destroy the Earth basically, right,
• 44:44
  Speaker 1: It's one of the most efficient ways to release the
• 44:46
  Speaker 1: energy inside matter, which is a huge amount, right equals
• 44:49
  Speaker 1: mc squared. C is a really big number. The speed
• 44:53
  Speaker 1: of light C squared is a really big number. Is squared.
• 44:56
  Speaker 1: So as you say, like a raisin's worth of antimatter
• 44:59
  Speaker 1: combined with the reason but have as much energy is
• 45:02
  Speaker 1: like a nuclear detonation. So yes, if you are making
• 45:05
  Speaker 1: antimatter in your kitchen, be very careful. Yeah, we're very
• 45:08
  Speaker 1: anti that kitchen. A recipe there, But I think what
• 45:12
  Speaker 1: you're saying is that you can make antimatter in your
• 45:15
  Speaker 1: colliders and certain, but you haven't made enough to really
• 45:18
  Speaker 1: do gravitational experiments to see whether antimatter feels anti gravity.
• 45:22
  Speaker 1: We actually have done a few experiments with antimatter that
• 45:25
  Speaker 1: do ask this question about the effects of gravity on
• 45:28
  Speaker 1: these particles, but they're very, very difficult to do and
• 45:31
  Speaker 1: not as sensitive as we'd like yet. What I mean,
• 45:33
  Speaker 1: so you did the experiments but didn't reach a conclusion
• 45:35
  Speaker 1: or what couldn't get the data. So they've done the experiments.
• 45:38
  Speaker 1: They take anti protons and they combine them with anti
• 45:41
  Speaker 1: electrons to make anti hydrogen. And the reason they do
• 45:45
  Speaker 1: that is you need neutral antimatter. You don't want any
• 45:48
  Speaker 1: electric or magnetic fields affecting your antimatter. You want to
• 45:51
  Speaker 1: measure only the gravitational force on these objects. So they
• 45:55
  Speaker 1: make neutral anti hydrogen, which is super awesome anyway, because
• 45:59
  Speaker 1: then they can do things like study the spectral properties
• 46:01
  Speaker 1: of it and see if anti hydrogen behaves the same
• 46:04
  Speaker 1: way as hydrogen, which this whole other really fascinating field
• 46:07
  Speaker 1: of science to try to figure out what is the
• 46:09
  Speaker 1: difference between matter and antimatter. But because they have a
• 46:12
  Speaker 1: collection of these anti hydrogen atoms, they can also see
• 46:16
  Speaker 1: like what happens when they float there, Like do they
• 46:18
  Speaker 1: drift down or do they drift up? Well, I guess,
• 46:21
  Speaker 1: first of all, how do you hold a bunch of
• 46:23
  Speaker 1: anti hydrogen? So you create this I guess by bringing
• 46:27
  Speaker 1: together anti electrons and anti protons, and then they make
• 46:30
  Speaker 1: answer hydrogen and then you get a little cloud of
• 46:32
  Speaker 1: anti hygen. What do you do with that? Do you
• 46:34
  Speaker 1: keep it inside of a bottle? It's really challenging to contain.
• 46:36
  Speaker 1: You're absolutely right. What we do is we keep it
• 46:38
  Speaker 1: in a magnetic bottle. It doesn't work very well. A
• 46:41
  Speaker 1: magnetic bottle is good at holding charged particles. Because magnetic
• 46:44
  Speaker 1: fields bend the path of charged particles. So, for example,
• 46:48
  Speaker 1: the beams and the large hadron collider are kept moving
• 46:50
  Speaker 1: in a circle because of very powerful magnets or plasma,
• 46:53
  Speaker 1: and a fusion reactor is kept in a magnetic bottle
• 46:55
  Speaker 1: to keep it from escaping because it's filled with charge particles.
• 46:59
  Speaker 1: It doesn't work very well all on neutral particles, but
• 47:01
  Speaker 1: even anti hydrogen has a magnetic moment because the spins
• 47:05
  Speaker 1: the particles, they do feel magnetic fields a little bit,
• 47:09
  Speaker 1: so we can keep them in like a very very
• 47:11
  Speaker 1: bad magnetic bottle, and it works best if those anti
• 47:14
  Speaker 1: hydrogen atoms are slow, if they're cold, they're not like
• 47:17
  Speaker 1: flying around with high velocity, then this very weak bottle
• 47:21
  Speaker 1: tends to contain them. But that's a challenge because making
• 47:24
  Speaker 1: anti hydrogen that's moving slowly is hard because you have
• 47:28
  Speaker 1: to combine the positrons and the anti protons which come
• 47:32
  Speaker 1: in in beams, so you have to have like slow beams,
• 47:35
  Speaker 1: like gases of these things like merge together. The whole
• 47:38
  Speaker 1: thing is experimentally very tricky. Yeah, it sounds pretty hard,
• 47:42
  Speaker 1: but they have done this kind of and what did
• 47:44
  Speaker 1: they find. Did they find that it falls at the
• 47:46
  Speaker 1: bottom of this bad bottle, or does it flow it
• 47:48
  Speaker 1: up to the top of the bad bottle. So there's
• 47:50
  Speaker 1: a very cool experiment at CERN. It's called the Alpha experiment,
• 47:53
  Speaker 1: which stands for anti hydrogen laser physics apparatus. Is a
• 47:58
  Speaker 1: terrible acronym or really awesome experiment. And they do not
• 48:02
  Speaker 1: see anti matter falling upwards very fast. I mean, some
• 48:04
  Speaker 1: of these hydrogen atoms do float up and some of
• 48:07
  Speaker 1: them do float down. And because the difficulty of measuring gravity,
• 48:11
  Speaker 1: it's not a very precise measurement. What they can do
• 48:14
  Speaker 1: is they can say that anti hydrogen doesn't have a
• 48:18
  Speaker 1: negative gravitational mass of sixty five times the inertial mass.
• 48:23
  Speaker 1: So if anti hydrogen had a negative gravitational mass of
• 48:26
  Speaker 1: like a hundred or a million times the inertial mass,
• 48:29
  Speaker 1: they would have seen it because they would have flown
• 48:31
  Speaker 1: upwards really fast. They don't see them flying upwards really fast,
• 48:34
  Speaker 1: so they can say if it does have a negative
• 48:37
  Speaker 1: gravitational mass, it's not that big. So it's like very imprecise.
• 48:41
  Speaker 1: So far, if they had a lot more anti hydrogen
• 48:44
  Speaker 1: or more time, they can make more precise measurements. They
• 48:47
  Speaker 1: could sort of narrow this down statistically, all they can
• 48:50
  Speaker 1: do right now is like rule out a really crazy
• 48:52
  Speaker 1: result where anti hydrogen has a negative gravitational mass that's
• 48:57
  Speaker 1: also much bigger in magnitude in the inertial mass. But
• 49:01
  Speaker 1: could it have a varying different gravitational mass in magnitude
• 49:05
  Speaker 1: than than it's inertial mass. I mean, we're exploring the
• 49:07
  Speaker 1: bonkers universe theory out here, so maybe right. And this
• 49:11
  Speaker 1: is also sort of like just the way that they
• 49:13
  Speaker 1: can express their results. Even if the theoretical options are well,
• 49:16
  Speaker 1: it either has a positive gravitational mass or negative one
• 49:20
  Speaker 1: times the inertial mass. We can't tell the difference between
• 49:23
  Speaker 1: those two. Experimentally, all we can do is tell the
• 49:25
  Speaker 1: difference between negative sixty five and positive one. So we
• 49:29
  Speaker 1: can rule out negative sixty five, we can't yet rule
• 49:32
  Speaker 1: out negative one. M I see. So they done the
• 49:35
  Speaker 1: experiment and they don't have a clear result, but it's
• 49:38
  Speaker 1: not an anti result either. It's not. And they're just
• 49:41
  Speaker 1: getting started, right, and so they're going to make more
• 49:43
  Speaker 1: anti hydrogen and they're gonna do more precise experiments. There
• 49:46
  Speaker 1: are other experiments coming online at CERN to measure this
• 49:49
  Speaker 1: in other ways and so in the next few years
• 49:51
  Speaker 1: we hope to get more precise measurements of the gravitational
• 49:55
  Speaker 1: properties of antimatter. All right, Besides cern are there other
• 49:59
  Speaker 1: experiment is that we've done or are going to do
• 50:02
  Speaker 1: to measure the gravity of antimatter. These kind of particle
• 50:05
  Speaker 1: physics experiments are really the most direct way to probe this.
• 50:08
  Speaker 1: You can also do other sort of thought experiments to
• 50:11
  Speaker 1: think about the effects of antimatter. For example, like the
• 50:14
  Speaker 1: protons that are inside me and you, we talked earlier
• 50:18
  Speaker 1: about how they have quarks inside them, Well, they also
• 50:21
  Speaker 1: have antimatter inside them. Like the gluons that are inside
• 50:25
  Speaker 1: the protons, they sometimes turn into cork anti cork pairs
• 50:29
  Speaker 1: like very briefly before going back to being a gluon
• 50:32
  Speaker 1: the way like a photon will turn into a particle
• 50:34
  Speaker 1: antiparticle pair briefly and go back to being a photon.
• 50:38
  Speaker 1: So that means that like you and I are partially
• 50:40
  Speaker 1: made of anti matter. If antimatter had anti gravity in
• 50:44
  Speaker 1: some weird way, then we would see the effect of
• 50:47
  Speaker 1: that on protons. And we don't see any weird behavior
• 50:51
  Speaker 1: of protons. They don't seem to have any sort of
• 50:52
  Speaker 1: like deviation between their inertial and gravitational mass. So that's
• 50:56
  Speaker 1: a strong hint that antimatter probably has normal. Yeah, we
• 51:00
  Speaker 1: all have a little bit of negativity inside of us,
• 51:03
  Speaker 1: a little bit of a contrarian inside of us. But
• 51:05
  Speaker 1: I think you're saying that we all are made a
• 51:08
  Speaker 1: little bit of antimatter and it doesn't seem to be
• 51:10
  Speaker 1: affecting the regular matter. But at the same time, it's
• 51:12
  Speaker 1: a very tiny amount, isn't Isn't it like super duper
• 51:15
  Speaker 1: negligible the amount of antimatter inside of us? Yeah, so
• 51:18
  Speaker 1: it would be pretty negligible. All right. Well, maybe to
• 51:21
  Speaker 1: wrap up here, I think we've sort of maybe a
• 51:23
  Speaker 1: little bit debunked the idea of anti gravity for antimatter particles.
• 51:27
  Speaker 1: I mean, theoretically, it seems like it's not really possible,
• 51:30
  Speaker 1: or I mean it's possible, but we would mean we
• 51:33
  Speaker 1: would see a very different universe. And also these experiments
• 51:36
  Speaker 1: that you describe kind of rule it out as well.
• 51:39
  Speaker 1: So if that's true, then if you can't have anti gravity,
• 51:44
  Speaker 1: what does that mean about our theories of the universe.
• 51:47
  Speaker 1: I think I agree mostly with what you say, but
• 51:49
  Speaker 1: I always hold out a little bit of hope for
• 51:51
  Speaker 1: the crazy result. You know, even if the theory very
• 51:54
  Speaker 1: strongly says that can't happen, that just makes me more
• 51:57
  Speaker 1: excited to go and discover it that way, because it
• 51:59
  Speaker 1: means undermining that whole theory and starting from scratch, and
• 52:03
  Speaker 1: to me, those are the most exciting moments in science.
• 52:06
  Speaker 1: So I think you're right that the theory very strongly
• 52:08
  Speaker 1: suggests that antimatter doesn't have anti gravity, But that still
• 52:11
  Speaker 1: makes me hopeful. Wait, what makes you hopeful that maybe
• 52:14
  Speaker 1: one of these experiments will get a shocking result and
• 52:16
  Speaker 1: discover antimatter fluting up in a gravitational field and give
• 52:20
  Speaker 1: us a clue about the next direction we should take
• 52:22
  Speaker 1: for gravity, for understanding whether it is a quantum field
• 52:26
  Speaker 1: or whether space itself is quantized, and how to get
• 52:28
  Speaker 1: to quantum gravity. All right, well, I think what you're
• 52:32
  Speaker 1: trying to say is keep giving you money to run
• 52:34
  Speaker 1: these experiments just to make sure that the universe is
• 52:37
  Speaker 1: not actually crazy. I'd say, we never know where the
• 52:40
  Speaker 1: next surprise, where the great big learning moment about the universe,
• 52:43
  Speaker 1: will come, and so it makes a lot of sense
• 52:45
  Speaker 1: to go out there and do careful experiments and see
• 52:47
  Speaker 1: if the universe is the way we expect or not?
• 52:50
  Speaker 1: Where is to the anti way we expect? All right,
• 52:52
  Speaker 1: we'll stay tuned, as I guess we keep exploring this
• 52:56
  Speaker 1: idea of antimatter and what gravity actually is. I guess
• 53:00
  Speaker 1: it's hard to prove that there's such a thing as
• 53:02
  Speaker 1: anti gravity if we don't actually kind of know what
• 53:04
  Speaker 1: gravity is. That's a good point. We anti know gravity,
• 53:08
  Speaker 1: right like, It's still kind of up for the babe
• 53:10
  Speaker 1: whether general relativity, which is Einstein's theory, is right or not,
• 53:15
  Speaker 1: and how it matches up with quantum mechanics. It's one
• 53:18
  Speaker 1: of the deepest questions at the heart of modern physics,
• 53:20
  Speaker 1: how to unify these two pillars of our understanding of
• 53:24
  Speaker 1: the universe. All right, well, I guess we'll keep waiting
• 53:27
  Speaker 1: for news from the fringes of physics. We'll keep funding
• 53:30
  Speaker 1: those experiments. You mean it's above my pay grade? All right? Well,
• 53:33
  Speaker 1: we hope you enjoyed that or anti enjoyed that. Thanks
• 53:36
  Speaker 1: for joining us, See you next time. Thanks for listening,
• 53:47
  Speaker 1: and remember that. Daniel and Jorge Explain the Universe is
• 53:49
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• 53:53
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• 53:56
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