Latest / Daniel and Kelly’s Extraordinary Universe / Can you send messages without particles?

Transcript

Can you send messages without particles? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Orgey, did you get the outline I sent you for
0:10
Speaker 1: this episode? I did, well, I didn't hear back from
0:14
Speaker 1: you about it. Oh well, I guess you should only
0:15
Speaker 1: worry if you do hear bad from me. Oh, that's right,
0:18
Speaker 1: I forgot. No reply also means something. Yeah, you know
0:21
Speaker 1: what it means. It's all good, or it means I
0:24
Speaker 1: didn't see your email. Or maybe it means I'll just
0:26
Speaker 1: reply later. It sounds like a super position of quantum possibilities.
0:31
Speaker 1: That's right. Yes, I believe in Q mail, not email.
0:35
Speaker 1: I hope you don't get entangled with your inbox, and
0:38
Speaker 1: I am A box is a pretty big quantum mess,
0:41
Speaker 1: to be honest, maybe one day it will collapse. Well,
0:43
Speaker 1: you know what they say. I like to wave at
0:46
Speaker 1: my emails Estate fly By. I wonder if Schrodinger got email.
0:49
Speaker 1: He did and he didn't, right. Hi am worry On
1:07
Speaker 1: my cartoonist and the co author of Frequently Asked Questions
1:10
Speaker 1: about the Universe. Hi, I'm Daniel. I'm a particle physicist
1:13
Speaker 1: and a professor at U C Irvine, and I'm gonna
1:16
Speaker 1: do my best not to spend most of this podcast chuckling. Yeah,
1:20
Speaker 1: you should be explaining things Daniel not laughing. Well, we
1:22
Speaker 1: got an email from a listener this morning complaining that
1:25
Speaker 1: the chuckle time on the podcast has been going up.
1:28
Speaker 1: Oh really, am I getting too funny? Is that what
1:30
Speaker 1: you're saying? Or are you laughing at your own jokes?
1:32
Speaker 1: I'm not sure. Just too much chuckling overall, more content
1:36
Speaker 1: less chuckling, I see, more physics, less humor. Yeah, exactly,
1:39
Speaker 1: stop these spontaneous expressions of fun. Please, boy, you can't
1:44
Speaker 1: please everybody all the time. Well, we'll try to be
1:46
Speaker 1: more serious about it. We'll try, but we'll probably fail.
1:49
Speaker 1: But anyways, Welcome to our podcast, Daniel and Jorge Explain
1:52
Speaker 1: the Universe, a production of I Heart Radio in which
1:55
Speaker 1: we try to be serious about questions of the universe
1:57
Speaker 1: and have fun while doing it. We ask the biggest,
2:00
Speaker 1: deepest questions about how everything out there works. What, in
2:04
Speaker 1: the end are the fundamental rules of reality? Why is
2:07
Speaker 1: it even possible for us to understand them? Or is it?
2:11
Speaker 1: Can we import the rules of the universe into our
2:14
Speaker 1: minds so that they actually make sense to us? On
2:17
Speaker 1: this podcast we push against that frontier and trying to
2:20
Speaker 1: make sure that you understand everything that humans do and
2:24
Speaker 1: do not know about the universe. That's right, because what
2:27
Speaker 1: could be more fun than exploring this humongous and complex
2:30
Speaker 1: and complicated and amazing universe, And what could be more
2:33
Speaker 1: chuckleworthy than thinking that us humans can one day understand
2:37
Speaker 1: all of it. It does seem sometimes like the universe
2:40
Speaker 1: is playing a big joke on us. It's like, oh,
2:42
Speaker 1: it seems to work this way. If equals m A
2:44
Speaker 1: is totally right. No, actually, we were lying. It's a
2:47
Speaker 1: completely different set of rules. Are you saying quantum mechanics.
2:50
Speaker 1: It's just a big punchline. The whole thing is a
2:53
Speaker 1: psi op. Man. The universe is trying to psych us out.
2:56
Speaker 1: Let's see what we can get these humans to believe
2:58
Speaker 1: crazy stuff like true random nous. Well, you know we
3:01
Speaker 1: are part of the universe. Does that mean we're playing
3:03
Speaker 1: a joke on ourselves? Mmm? I suppose so, Yes, we
3:06
Speaker 1: are psyopping ourselves. I mean we're the joke. You have
3:11
Speaker 1: to say, you're the only one who doesn't get the
3:13
Speaker 1: joke that jokes on you. As long as I get
3:14
Speaker 1: to hear the secrets of the universe, I'm happy if
3:16
Speaker 1: somebody laughs at me at the same time. But it
3:18
Speaker 1: isn't interesting and sometimes funny universe because it is so weird.
3:22
Speaker 1: Especially Quantum mechanics is this weird theory about the universe.
3:25
Speaker 1: It says that things are truly random, and that sometimes
3:29
Speaker 1: there are multiple things that are true at the same time.
3:31
Speaker 1: It is really amazing that we can spend thousands of
3:34
Speaker 1: years developing an intuition for how the universe works, and
3:37
Speaker 1: then a few hundred years describing it mathematically, only to
3:41
Speaker 1: discover that at its core, at a deeper level, the
3:44
Speaker 1: rules of the universe are completely different, totally foreign to us,
3:48
Speaker 1: maybe even alien, and yet those alien rules somehow weave
3:52
Speaker 1: themselves together so that at our scale and our experience,
3:56
Speaker 1: they act in the way that's intuitive to us. It's
3:58
Speaker 1: incredible that a difference aales the universe seems to follow
4:01
Speaker 1: these totally different sets of laws, incongruent ideas about the
4:05
Speaker 1: very nature of space and time and information, and yet
4:08
Speaker 1: they weave themselves together at the interface. It's incredible. Yeah,
4:12
Speaker 1: are you saying quantum mechanics is just a tiny little joke.
4:15
Speaker 1: It's only funny in small places. It's like ten to
4:18
Speaker 1: the twenty six tiny jokes, which all add up to
4:20
Speaker 1: one hilarious chuckle. To one average bland experience of the
4:24
Speaker 1: universe exactly until the universe collapses on the weight of
4:27
Speaker 1: its own puns. But quantum mechanics says the universe gets
4:30
Speaker 1: really weird at the very smallest scales, which maybe you
4:32
Speaker 1: don't think affects you on an everyday basis, but it
4:35
Speaker 1: actually does. You know, most of our electronics and a
4:37
Speaker 1: lot of our communications, and all of our devices, they
4:40
Speaker 1: all sort of are depend on our knowledge of quantum mechanics,
4:44
Speaker 1: and as we try to understand the way that the
4:46
Speaker 1: universe works, we tend to revert to this microscopic picture.
4:49
Speaker 1: When we say we want to understand the universe, some
4:52
Speaker 1: of us feel like we want to tear it apart
4:54
Speaker 1: into the tiniest little pieces, figure out what are the
4:56
Speaker 1: rules of those little pieces, how do they interact? And
4:59
Speaker 1: then how do you zoom back out to get the
5:01
Speaker 1: picture of the universe that we're familiar with. And so
5:04
Speaker 1: often in quantum mechanics, we are thinking about little particles,
5:07
Speaker 1: tiny little quantum objects, and what are the rules for
5:10
Speaker 1: those things? Do they fly through space the way baseball does,
5:13
Speaker 1: or do they appear just in snapshots? How do they
5:16
Speaker 1: communicate information back and forth? And how does that change
5:19
Speaker 1: how we can communicate up here at the big, slow
5:22
Speaker 1: human scale. That's right, because if quantum mechanics does lead
5:25
Speaker 1: you do some weird things that we didn't think about before,
5:27
Speaker 1: it might change the way that we can maybe make
5:30
Speaker 1: devices or allow us to communicate between different points on Earth. Exactly.
5:35
Speaker 1: If the rules of quantum mechanics really are strange, alien
5:38
Speaker 1: to our intuition, then maybe we can make quantum mechanics
5:41
Speaker 1: do things at our scale that are very weird that
5:44
Speaker 1: we once thought might be impossible. Coming to the Apple
5:48
Speaker 1: Store soon alien iPhones? Is that what you're saying? Excuse
5:53
Speaker 1: my long chuckle there. That was pretty funny. Well, I'm sorry, man,
5:57
Speaker 1: already going to get a lot of complaints. Stop laughing, Danny,
6:01
Speaker 1: think that the chuckle time is just increasing. The first
6:03
Speaker 1: rule of chuckle time is don't talk about chuckle time.
6:06
Speaker 1: It just makes more chuckle time. That's right. Although usually
6:08
Speaker 1: talking about the joke kills the joke. We've collapsed it again,
6:12
Speaker 1: and so quantum mechanics may open some interesting possibilities for
6:14
Speaker 1: future technologies and so. On the podcast today, we'll be
6:18
Speaker 1: tackling the question can you send messages without particles? Is
6:28
Speaker 1: that like sending emails without replies That happens all the time, actually,
6:32
Speaker 1: but this has to do more with how information propagates
6:35
Speaker 1: in a quantum universe. We like to think about everything
6:38
Speaker 1: happening in terms of the microscopic particles, and usually that
6:41
Speaker 1: picture involves local interactions, meaning like one particle pushes against
6:46
Speaker 1: another particle, which pushes against another. I think about how
6:49
Speaker 1: electricity flows. You can think about just flowing down the wire,
6:53
Speaker 1: but if you zoom into the particles, it's one electron
6:55
Speaker 1: jumping from spot to spot and pushing other electrons. You
6:58
Speaker 1: can build up this idea of electory city from the
7:00
Speaker 1: little microscopic particles and how they touch each other. Usually
7:04
Speaker 1: there's this crucial bit where they need to be near
7:06
Speaker 1: each other, where everything has to be local. Is that
7:09
Speaker 1: kind of like how my wife communicates a lot to
7:11
Speaker 1: me just by giving me certain looks. I think that's
7:13
Speaker 1: actually telepathic, man, I think that might break the laws
7:16
Speaker 1: of physics. Usually they're not good messages. I get the looks.
7:21
Speaker 1: I don't know if we should be doing marriage therapy
7:22
Speaker 1: on the podcast. We already have too many chuckles. Well, yeah,
7:25
Speaker 1: because you know, no marriage needs more chuckles Every marriage
7:29
Speaker 1: needs more chuckles. Man, humor is the best therapy the
7:32
Speaker 1: tense and what they are chuckling at. You gotta take
7:35
Speaker 1: your wife seriously, that's for sure. But yeah, usually communication
7:38
Speaker 1: involves some sort of interaction between particles, right, Even if
7:41
Speaker 1: you're just giving somebody look to communicate something to them,
7:44
Speaker 1: you're exchanging photons, right, that's right. Our picture of how
7:47
Speaker 1: we communicate involves sending particles or waves through fields, which
7:51
Speaker 1: you can also think of as particles. But everything involves
7:55
Speaker 1: somehow wiggling a field or sending a particle using that
7:58
Speaker 1: to communicate in form asian. Yeah, because I guess you know,
8:01
Speaker 1: in the universe we have a certain speed of light, right,
8:04
Speaker 1: a speed of information like you can't somehow, it seems,
8:08
Speaker 1: move things from one place to another without going faster
8:11
Speaker 1: than the speed of light. That's right. It's pretty hard
8:12
Speaker 1: coded into special relativity that no information can move faster
8:17
Speaker 1: than the speed of light, and even quantum mechanics, which
8:19
Speaker 1: does really weird things, doesn't violate that rule, although sometimes
8:24
Speaker 1: it seems like it might. M And so I guess
8:27
Speaker 1: the question here is, can you somehow communicate, send messages,
8:31
Speaker 1: interact between two places in the universe without actually exchanging
8:36
Speaker 1: a particle or wiggle in some kind of particle field. Exactly,
8:40
Speaker 1: could you somehow send a message to your body on
8:42
Speaker 1: Alpha Centauri without having to shoot him an electron or
8:45
Speaker 1: a beam of photons or some other kind of particle
8:49
Speaker 1: or wave based information. It sounds like we're asking does
8:52
Speaker 1: magic exist? You know, quantum mechanics feels like magic sometimes,
8:58
Speaker 1: you know, it does things that we think are impossible.
9:00
Speaker 1: You know, an electron can be here and then it
9:02
Speaker 1: can be there without going in between, even if sometimes
9:06
Speaker 1: the spot in between is impossible for the electron to
9:09
Speaker 1: be in. You can have an electron appear on one
9:11
Speaker 1: side and then the other side of an infinite barrier.
9:14
Speaker 1: It's crazy. That seems like magic, and yet we see
9:18
Speaker 1: it happen in our universe. Would you describe it as
9:21
Speaker 1: magic though, or is it maybe like scientific magic because
9:25
Speaker 1: you can maybe you know, statistically predict what's going to happen. Yeah,
9:28
Speaker 1: it's only magic until we explain it. Then it's science again,
9:31
Speaker 1: then it's not magical. Science has been ruining the magic
9:34
Speaker 1: of the universe for hundreds of years well, as usually,
9:36
Speaker 1: we were wondering how many people had thought about this
9:38
Speaker 1: question or think it's possible to maybe send messages without
9:42
Speaker 1: using particle or particle fields. So thank you very much
9:45
Speaker 1: to our cadre of volunteers who answer these questions without
9:48
Speaker 1: any preparation to give us a sense for what people
9:51
Speaker 1: are thinking about and to give you a sense what
9:53
Speaker 1: everyone else out there is thinking. If you'd like to
9:56
Speaker 1: participate for future episodes of the podcast, especially if you
10:00
Speaker 1: you've never done so before and you're a long time listener,
10:02
Speaker 1: please do reach out our email addresses questions at Daniel
10:06
Speaker 1: and Jorge dot com. So think about it for a second.
10:08
Speaker 1: Do you think it's possible in this universe to send
10:11
Speaker 1: a message without using particles? Here's what people had to say.
10:15
Speaker 1: I think, no, you can't. Well, oh no, no no,
10:19
Speaker 1: because of like quantum computers and quantum entanglement. So theoretically,
10:23
Speaker 1: if we have to quantum lee entangled particles, we could
10:26
Speaker 1: send information and thus send a message between those two
10:29
Speaker 1: particles without sending particles from one location to another. When
10:35
Speaker 1: I'm thinking about these questions, actually I'm thinking about quantum entanglement.
10:42
Speaker 1: How you can send you formation from one point to
10:46
Speaker 1: another faster than the speed of light. Scientists hope this
10:50
Speaker 1: will be it like quantum entanglement, but I don't know
10:55
Speaker 1: too many information right now, I don't think No, I
10:57
Speaker 1: don't think that's possible. I think maybe the closest thing
11:04
Speaker 1: to sending information without particles that were currently looking at
11:09
Speaker 1: is gravitational waves. But then how's that possible. I think
11:15
Speaker 1: that that's just a shift in gravitons, So no, I
11:20
Speaker 1: don't think so. I think the only way to send
11:22
Speaker 1: a message without sending any particles might be through quantum entanglement,
11:26
Speaker 1: but I'm not even sure if that counts, since I'm
11:28
Speaker 1: pretty sure we can't affect the state of the entangled particles.
11:33
Speaker 1: We can just observe them, So I'm not sure we
11:35
Speaker 1: can actually pass a message through that. That depends on
11:37
Speaker 1: what you mean by particles. If you mean pheromons, then yes,
11:40
Speaker 1: you can send a message with argues and particles because
11:44
Speaker 1: photons can carry information. But if you mean any particle
11:49
Speaker 1: if you include photons, then you can't because I think
11:53
Speaker 1: you need some entity lack of photon that carries energy
11:57
Speaker 1: to transfer information. Well, everything in the universe of ib
12:00
Speaker 1: made of particles, so I'm not really sure how you
12:02
Speaker 1: would be able to send any message without them. But
12:04
Speaker 1: I'm also thinking maybe you could send a message with
12:07
Speaker 1: a lack of particles. So say someone's on the moon
12:10
Speaker 1: and you make a really big shadow with your hand
12:13
Speaker 1: in a really powerful light, and that person on the
12:16
Speaker 1: moon knows that when the shadow passes over them that
12:20
Speaker 1: means X or Y, and I guess technically that would
12:23
Speaker 1: be sending a message with a lack of particles, if
12:26
Speaker 1: that makes any sense, But otherwise I don't see any
12:29
Speaker 1: other way. Al Right, not a lot of optimism. Most
12:33
Speaker 1: people are like, well, a few mentions of quantum entanglement. Yeah,
12:37
Speaker 1: we have a pretty educated and listener crowd. On physics,
12:41
Speaker 1: a few people said quantum entanglement, yeah, and quantum entangling
12:44
Speaker 1: the sort of the right direction to think about, because
12:47
Speaker 1: that's the non local part of quantum mechanics, the fact
12:51
Speaker 1: that things can happen in a correlated way across space
12:55
Speaker 1: even if things are causally separated. So that's definitely the
12:58
Speaker 1: right direction to be thinking about, right. And somebody try
13:01
Speaker 1: to make a distinction between like different kinds of particles, right,
13:04
Speaker 1: because there are some matter particles like the stuff we're
13:07
Speaker 1: made out of, and then there are other particles, which
13:09
Speaker 1: you know are more intangible exactly. In the end, we
13:12
Speaker 1: can think about all of those as particles, or you
13:14
Speaker 1: can think about all of them as fields. In theoretical
13:17
Speaker 1: particle physics, this sort of this argument about whether fields
13:20
Speaker 1: or particles are the most basic thing in the universe.
13:23
Speaker 1: But fundamentally we're all talking about the same kind of stuff,
13:26
Speaker 1: like can you send a message without a field at all?
13:28
Speaker 1: Or disturbing any field? Well, you know, some people think
13:31
Speaker 1: that fields don't even exist, the fields are just like
13:33
Speaker 1: a mathematical construct in our minds, that particles are the
13:37
Speaker 1: only real thing because you don't ever see fields, right,
13:39
Speaker 1: You can't interact with the field except for seeing its
13:42
Speaker 1: effect on a particle. So some people don't even think
13:45
Speaker 1: fields are real, that everything is just particles. But then
13:48
Speaker 1: those people are just imaginary too. So there's even a
13:50
Speaker 1: guy who developed a version of physics without fields and
13:53
Speaker 1: even without numbers. What ironically his last name was Fields, ironic,
13:59
Speaker 1: I say, you're can say ironically his name was whit
14:01
Speaker 1: sund no Archery. Fields is a philosopher of physics, and
14:05
Speaker 1: you word a book called Science Without Numbers, in which
14:08
Speaker 1: he argues that fields are just a made up thing
14:10
Speaker 1: and you don't need them at all. Of course, he
14:12
Speaker 1: thinks he's real, you know, he's a field, and he
14:15
Speaker 1: just wanted to be the only field in the universe,
14:18
Speaker 1: the field field. But yeah, this is an interesting question.
14:20
Speaker 1: Can you communicate without particles? And so let's dig into Daniel.
14:24
Speaker 1: Let's start with, first of all, messaging with particles. How
14:27
Speaker 1: does that work? How do we usually send information? So
14:29
Speaker 1: almost all the information that we transmit use either particles
14:32
Speaker 1: or waves, and really those two are equivalent. You can
14:35
Speaker 1: think of every particle as a wave in some quantum field,
14:39
Speaker 1: or if you like, you can think of quantum fields.
14:41
Speaker 1: It's just like an infinite sum of possible particles. It's
14:44
Speaker 1: all really fundamentally equivalent. You know, when you send an email,
14:47
Speaker 1: for example, what are you doing. You're sending a message
14:50
Speaker 1: along some wires, and those messages are wiggles in those
14:54
Speaker 1: little fields. You send a beam of light at somebody
14:56
Speaker 1: right your friend across the street has an open window,
14:59
Speaker 1: and you've turned your flashlight on and off. Then you
15:02
Speaker 1: are sending beams of photons, which you can think of
15:04
Speaker 1: either as ripples in the electromagnetic field of the universe
15:07
Speaker 1: or little packets, little particles that are flying through space.
15:11
Speaker 1: Either way, you're transmitting that information through particles and fields. Right.
15:15
Speaker 1: Even when you talk on your cell phone out there,
15:17
Speaker 1: you're using light as well, right, Like your cell phone
15:21
Speaker 1: is transmitting light at the really high frequency that you
15:24
Speaker 1: can't see, but it's it's light, right, And then the
15:26
Speaker 1: cell phone antenna and towers out there are also communicating
15:29
Speaker 1: with your cell phone through light exactly. And you even
15:32
Speaker 1: have transformation of information there because the neural pulses go
15:36
Speaker 1: through your mind and those are electrical pulses, and then
15:39
Speaker 1: your mouth transforms them into sound waves, which is just
15:43
Speaker 1: shaking of the air. Then the microphone in your cell
15:46
Speaker 1: phone translates them back into a different kind of electrical pulses,
15:50
Speaker 1: which then get emitted by your phone as electromagnetic pulses,
15:53
Speaker 1: because that's just another kind of photon, one with very
15:56
Speaker 1: long frequency. And in all of those steps we have
15:59
Speaker 1: a micro pas to call picture of what's going on.
16:02
Speaker 1: Atoms pushing against other atoms, or photons flying through the
16:05
Speaker 1: electromagnetic fields that fill the whole universe. It's always local.
16:09
Speaker 1: It's always like one thing pushing another thing. It's like
16:12
Speaker 1: a Rube Goldberg machine. Right, Everything is coming into sort
16:15
Speaker 1: of effective contact with something else. Right, And even your
16:18
Speaker 1: voice uses the electromagnetic radiation and forces, right, Like when
16:22
Speaker 1: the air particles are pushing against each other, they're pushing
16:25
Speaker 1: against each other using the electromagnetic force, which means they're
16:28
Speaker 1: also exchanging photons. Right, Yeah, that's exactly right. The reason
16:32
Speaker 1: that air particles don't pass through each other, they can't
16:35
Speaker 1: occupy the same space, is primarily because their electrons bump
16:38
Speaker 1: against each other. They resist and repel. And you're right,
16:41
Speaker 1: that's done either through electromagnetic fields or virtual photons, depending
16:46
Speaker 1: on the picture that you prefer. But all that stuff
16:48
Speaker 1: requires some sort of passage of wiggles in fields or particles. Yeah,
16:53
Speaker 1: even your voice is light, pure like kind of right,
16:57
Speaker 1: even when I'm talking about heavy topics or emanating topics
17:00
Speaker 1: as well, or chuckling to the chuckles are made of
17:03
Speaker 1: pure light as well, Daniel. And light is really one
17:05
Speaker 1: of our primary ways to interact in the universe. When
17:08
Speaker 1: stars send us light from across the vast distances of space,
17:12
Speaker 1: those are also photons. It's created a particle which is
17:15
Speaker 1: shot out from the surface of that sun and then
17:18
Speaker 1: flown to many megaparsecs before it hits your eyeball. That
17:21
Speaker 1: information that the star exists and what it's temperature is
17:24
Speaker 1: and where it is comes along with the photon. Yeah,
17:28
Speaker 1: and that's not the only particle we get information from
17:31
Speaker 1: and from the universe, right, And we also get lots
17:33
Speaker 1: of other particles coming at us and telling us things
17:36
Speaker 1: about the universe. Yeah. Now we have multi messenger astronomy,
17:39
Speaker 1: which means that we can see things out there in
17:41
Speaker 1: the universe, not just using photons. So, for example, we
17:44
Speaker 1: can see other particles. Protons hit the atmosphere at very
17:48
Speaker 1: high speed. Some of them are generated by the Sun,
17:50
Speaker 1: some of them come from outside the Solar system. These
17:53
Speaker 1: things we call cosmic rays can carry a lot of
17:56
Speaker 1: information about what's going on out there in the galaxy.
17:59
Speaker 1: So that's only not a photon, right. A proton is
18:02
Speaker 1: a matter particle. It's made out of corks, which each
18:05
Speaker 1: are ripples in the cork fields that fill the universe.
18:08
Speaker 1: But just like a photon is a ripple in the
18:10
Speaker 1: electromagnetic field, these corks are ripples in the cork fields
18:14
Speaker 1: and they carry information exactly the same way that a
18:17
Speaker 1: photon does. Right. But then there are gravitational waves though, right,
18:21
Speaker 1: those are a sort of real information we're getting about
18:23
Speaker 1: the universe, something communicating something to us. But do we
18:26
Speaker 1: know if there are particles. Yeah, that's a great question.
18:28
Speaker 1: And there's a lot of confusion about gravitational waves versus gravitons.
18:33
Speaker 1: So gravitational waves happen to anytime anything in the universe
18:37
Speaker 1: with mass accelerates, like if two black holes fall into
18:41
Speaker 1: each other, the acceleration as they fall in their circling
18:44
Speaker 1: around each other generates gravitational waves, really big gravitational waves
18:48
Speaker 1: that we can detect. And this is a prediction of
18:50
Speaker 1: general relativity, which is a non quantum theory. It's a
18:53
Speaker 1: classical theory. It says that space and time are continuous
18:57
Speaker 1: and everything has a smooth path, really in conflict with
19:00
Speaker 1: our quantum view of the universe, but we see it.
19:02
Speaker 1: We see these things happening. We see these ripples in
19:05
Speaker 1: space and time. These are gravitational waves and their classical objects.
19:09
Speaker 1: But you know, there are waves in a field and
19:11
Speaker 1: they carry information and move at the speed of light,
19:14
Speaker 1: which is kind of awesome. We don't know if they're
19:16
Speaker 1: made of gravitons. It might be that gravity is in
19:20
Speaker 1: the end a quantum field theory like the other forces,
19:24
Speaker 1: and you can describe in terms of tiny little packets.
19:27
Speaker 1: But those packets, if they exist, they're too small for
19:29
Speaker 1: us to see. We're just barely able to even see
19:32
Speaker 1: gravitational waves. And one gravitational wave might be made out
19:35
Speaker 1: of an enormous number of tiny gravitons, so small that
19:39
Speaker 1: we can't resolve them, the way like a wave in
19:41
Speaker 1: the ocean is made of lots of droplets, but we
19:44
Speaker 1: can't separate them necessarily. Wait, so then, if gravitational waves
19:48
Speaker 1: are not made out of particles, and we've answered the
19:51
Speaker 1: question of the episode, I could send the message using
19:53
Speaker 1: gravitational waves without particles. Yeah, I suppose. So you can
19:57
Speaker 1: send information without particles if gravity is not a quantum theory.
20:01
Speaker 1: But you'd still be sending information via waves. And in
20:04
Speaker 1: the end, particles and waves, really, what's the difference. They're
20:07
Speaker 1: just two attempts by the human mind to describe something
20:10
Speaker 1: about the universe, which, in the end is unfamiliar. You know.
20:13
Speaker 1: Physics is the effort to describe the unfamiliar in terms
20:16
Speaker 1: of the familiar. And the reason we have an argument
20:18
Speaker 1: about whether to describe these things in terms of particles
20:21
Speaker 1: or fields or waves is because none of those are
20:24
Speaker 1: really the right description. They're just sort of like our
20:27
Speaker 1: attempt to capture them in terms of something we know,
20:29
Speaker 1: like when you drink a really tasty glass of wine
20:32
Speaker 1: and you're like, hm, hmmm, it's like vanilla and notes
20:34
Speaker 1: of oak or whatever. Now those aren't really there in
20:37
Speaker 1: the wine. They're just your efforts to describe them in
20:39
Speaker 1: terms of a language. You know, it sounds like you're
20:41
Speaker 1: trying to get out of something there, But I think
20:45
Speaker 1: what you're saying is that, you know, it's kind of
20:47
Speaker 1: hard to imagine communicating something across a distance in this
20:51
Speaker 1: universe without creating some sort of ripple that you know,
20:54
Speaker 1: moves through spaces. I think that's what you're saying. And
20:57
Speaker 1: gravitational waves are technically ripples through some sort of me
21:00
Speaker 1: m or some sort of field in the universe. And
21:02
Speaker 1: so the question then maybe is like can you actually
21:05
Speaker 1: communicate without causing any ripples in the universe. Yeah, we
21:09
Speaker 1: think about information is propagating through the universe. We think
21:12
Speaker 1: of everything is local. Something passes a note to the
21:15
Speaker 1: next thing, which passes a note to the next thing.
21:17
Speaker 1: You can't just have information appear somewhere far away. We
21:20
Speaker 1: think we have this intuition that the universe seems to
21:23
Speaker 1: be local, that information moves and propagates, so that to
21:26
Speaker 1: send information you've got to create some sort of ripple
21:29
Speaker 1: in a field. And think about really what a wave
21:31
Speaker 1: is like. If you think about a guitar string with
21:33
Speaker 1: a wave on it, why does it wave anyway? It
21:36
Speaker 1: waves because one bit of the string is then wiggling
21:38
Speaker 1: the next bit, which is wiggling the next bit, which
21:40
Speaker 1: is wiggling the next bit. Information about the wave is
21:43
Speaker 1: flowing down the string the same way like you're driving
21:46
Speaker 1: down the freeway. Why is everybody in front of you
21:48
Speaker 1: breaking because the person in front of them is breaking
21:51
Speaker 1: because their information is local. They just respond to the
21:54
Speaker 1: person in front of them. So the whole idea of
21:56
Speaker 1: a wave is sort of comes out of information being
21:59
Speaker 1: local and propagating locally. Right, all right, Well, it seems
22:02
Speaker 1: kind of impossible to maybe communicate or send information across
22:07
Speaker 1: the universe without causing any kind of a ripple. But
22:09
Speaker 1: let's see if that is actually true, and so let's
22:12
Speaker 1: get into how we might be able to do that.
22:14
Speaker 1: But first let's take a quick break. Alright, we're trying
22:29
Speaker 1: to send I guess Q mail messages without causing a
22:33
Speaker 1: ripple in the universe. What are you trying to do here?
22:35
Speaker 1: Then you're trying to send messages? Will let anybody finding out?
22:38
Speaker 1: I think it could be pretty awesome to be able
22:39
Speaker 1: to send information without creating any ripples or sending any particles.
22:43
Speaker 1: It's just be something new that we didn't think was
22:45
Speaker 1: possible before. It might open up new technologies that we
22:48
Speaker 1: can't even imagine today, because it would like break down
22:51
Speaker 1: one of our basic intuitions about how the universe works.
22:55
Speaker 1: You know, we're pretty sure that we're pretty wrong about
22:57
Speaker 1: some of these assumptions about the universe, things we've assumed
23:00
Speaker 1: for a long long time. One of them probably has
23:03
Speaker 1: to go. We just don't really know which yet. Yeah,
23:05
Speaker 1: I'm sure there are many politicians who would love to
23:07
Speaker 1: have the technology to send text messages without leaving a
23:12
Speaker 1: trace or a ripple through anything. Wow, you went straight
23:15
Speaker 1: for the cynical application, So those usually come first. We're
23:19
Speaker 1: thinking about how to pitch this to Facebook next, right,
23:22
Speaker 1: I'm sure they're on it. You know. The waste time
23:24
Speaker 1: chuckling about these things. But I think you were saying
23:26
Speaker 1: earlier how physicists sort of look at the universe and
23:30
Speaker 1: how things interact in it as being local or non local.
23:33
Speaker 1: So local just kind of means that you can't affect
23:36
Speaker 1: something that's really far away from you, kind of, right,
23:38
Speaker 1: Like the universe seems to have a sort of a
23:40
Speaker 1: short range of things. If I want to communicate something
23:42
Speaker 1: to you, I have to do it through a series
23:44
Speaker 1: of intermediary particles or things like that, right, or fields
23:48
Speaker 1: exactly have your people talk to my people. That's how
23:51
Speaker 1: these things get done. On the other hand, we also
23:53
Speaker 1: know that quantum mechanics has some very strange, very non
23:57
Speaker 1: local features to it. It seems to be able to
24:00
Speaker 1: do things across space time that sounds sort of impossible. Yeah,
24:05
Speaker 1: And so that's maybe the question we're asking here today
24:07
Speaker 1: is can we exploit can we use some of this
24:09
Speaker 1: weird quantum mechanical magic to maybe send messages without causing
24:14
Speaker 1: a ripple in any of the quantum fields. And we
24:16
Speaker 1: heard several of our listeners suggest maybe using quantum entanglement,
24:21
Speaker 1: which is a great idea because quantum entanglement really highlights
24:24
Speaker 1: the non local nature of quantum mechanics. You know, so
24:27
Speaker 1: very briefly, the idea of entanglement. You have two particles
24:31
Speaker 1: that are somehow connected. You know something about them, like
24:34
Speaker 1: if one is spin up, the other one has to
24:36
Speaker 1: be spinned down because of the way they were created.
24:38
Speaker 1: You know, or imagine you have two balls and you
24:40
Speaker 1: know that only one of them can be read and
24:42
Speaker 1: the other one has to be blue. But maybe you
24:43
Speaker 1: don't know which is which. So quantum entanglement says, you
24:46
Speaker 1: have these two particles, you know something about them overall
24:49
Speaker 1: that makes them have like opposite states or different colors
24:52
Speaker 1: or something, but you don't know which is which. They
24:54
Speaker 1: just have to be in the opposite states. And quantum
24:56
Speaker 1: mechanics says that they can stay uncertain. That you can
24:59
Speaker 1: have one particle have a possibility of being up in
25:01
Speaker 1: the possibility of being down, and the other particle also
25:04
Speaker 1: maintained both of those possibilities. I take these two particles
25:08
Speaker 1: and pull them really far apart a kilometer, ten kilometers,
25:11
Speaker 1: a thousand kilometers or whatever. They can maintain those possibilities.
25:15
Speaker 1: And if you look at the first particle and you say, oh,
25:17
Speaker 1: it's up, that means that the other particle, even though
25:19
Speaker 1: it's super duper far away and there's no time for
25:22
Speaker 1: information to get to it, all of a sudden goes
25:25
Speaker 1: from having both possibilities to having to be down because
25:28
Speaker 1: the first one was up, the second one has to
25:30
Speaker 1: be down. You know that because of how they were created.
25:33
Speaker 1: The quantum entanglement definitely is a weird, non local part
25:36
Speaker 1: of quantum mechanics. I guess that's the confusing part about
25:39
Speaker 1: this whole entanglement thing, right. It's that like if you
25:42
Speaker 1: you would think that if I had two balls, one
25:44
Speaker 1: red and one blue, and I put them in a
25:46
Speaker 1: bag and I make them up, then I take one
25:48
Speaker 1: out without looking at it, and I drive it over
25:50
Speaker 1: to the other side of the country. Obviously, if I
25:53
Speaker 1: see that it's red and the one that stayed behind
25:55
Speaker 1: is going to be blue, or or if I look
25:57
Speaker 1: at the one over there and it's blue and then
25:58
Speaker 1: this one has to be red, that's it. It It seems obvious.
26:00
Speaker 1: But I guess the tricky thing about quantum mechanics is
26:03
Speaker 1: that they're not balls, right, They're quantum mechanical objects. Like
26:07
Speaker 1: when you separate the two balls, it's not like one
26:09
Speaker 1: of them is red and you just don't see it.
26:11
Speaker 1: It's like it's they're both both red and blue at
26:14
Speaker 1: the same time. In quantum mechanics, they're both actually undetermined, right,
26:18
Speaker 1: the universe hasn't decided which one is red and which
26:21
Speaker 1: one is blue. This this whole beautiful series of experiments
26:24
Speaker 1: in Bell's experiments that asked the question, as the universe
26:28
Speaker 1: actually decided in advance, is it really determined and we
26:30
Speaker 1: just don't know the answer, or is it actually undetermined
26:33
Speaker 1: the whole time? And we'll have a whole episode about
26:36
Speaker 1: Bell's experiments soon. But those experiments determine that there's no
26:40
Speaker 1: local hidden variables. There's no information that's traveling along with
26:43
Speaker 1: those particles that somehow determines which one is red and
26:46
Speaker 1: which one is blue. That you have some sort of
26:48
Speaker 1: nonlocal effect. They're either they're communicating somehow, or there's some
26:52
Speaker 1: sort of like global plan that affects everything. Right, And
26:56
Speaker 1: I guess from a lay person point of view, like
26:59
Speaker 1: it's hard to swallow, you know, Like you I would think, like, hey,
27:02
Speaker 1: it's not that the ball is red and blue, it's
27:05
Speaker 1: just you just don't know what it is. But inside
27:07
Speaker 1: the bag, the ball knows if it's red or blue. Right,
27:10
Speaker 1: that's our intuition, because that's the way that our world works. Right.
27:13
Speaker 1: We think that there's a truth that everything is determined.
27:15
Speaker 1: We just don't have all the information. But quantum mechanics
27:18
Speaker 1: really does seem to operate differently, really does seem to
27:21
Speaker 1: follow very different rules. That's what I was talking about earlier,
27:24
Speaker 1: that there are these weird, strange, almost alien ideas about
27:27
Speaker 1: how the universe works which really fly in the face
27:30
Speaker 1: of the things that we expected to do, and maybe
27:33
Speaker 1: that would let us build on those properties to do
27:35
Speaker 1: crazy bonkers things we thought were impossible. You know, whenever
27:38
Speaker 1: we talk about entanglement on the podcast, get a few
27:41
Speaker 1: emails from folks who ask, isn't it possible to use
27:43
Speaker 1: entanglements somehow to communicate faster than light? Because it seems
27:47
Speaker 1: like there's this faster than light process here you're looking
27:51
Speaker 1: at one of the particles and deciding whether it's up
27:53
Speaker 1: or down. Somehow the other one instantaneously goes from undetermined
27:57
Speaker 1: to determined, either up or down. So several listeners have
28:00
Speaker 1: emailed me with the scheme trying to use this to
28:03
Speaker 1: send information faster than light by, for example, collapse in
28:06
Speaker 1: one particle and noticing on the other end that the
28:09
Speaker 1: particles collapsed, using that to send information somehow. Unfortunately, that
28:13
Speaker 1: doesn't work because you can't tell whether your particle's wave
28:17
Speaker 1: function is collapsed. You can just measure it. You can say, oh,
28:20
Speaker 1: mine is red or blue. You can't tell whether the
28:22
Speaker 1: other person has measured their particle or not. So, as
28:25
Speaker 1: far as we know, there's no way to use this
28:28
Speaker 1: to send information faster than light. However, it does seem
28:32
Speaker 1: like there is something nonlocal going on, so maybe we
28:35
Speaker 1: just need to be more clever about it, right, I
28:37
Speaker 1: wonder maybe an interesting analogy to flesh out here is like,
28:40
Speaker 1: instead of having balls that are painted blue and red,
28:43
Speaker 1: maybe they're like transparent balls and they have a little
28:47
Speaker 1: led lights inside of them that turn red or blue.
28:51
Speaker 1: And so when you put them together inside of the bag,
28:53
Speaker 1: they somehow make the arrangement that one of them is
28:56
Speaker 1: going to turn blue the other one turns red, and
28:58
Speaker 1: if the other one turns red, the other is going
29:00
Speaker 1: to turn blue. They make that arrangement, and then you
29:03
Speaker 1: take the ball off and you separate them, and you
29:05
Speaker 1: take one to the other side of the country, and
29:06
Speaker 1: you keep one of them. Now, I think the magic
29:09
Speaker 1: sort of happens if I look at the one I
29:11
Speaker 1: have here and it turns blue. Somehow the one and
29:15
Speaker 1: the other on the other side of the country has
29:16
Speaker 1: to know to turn red. But they're separated by a
29:19
Speaker 1: huge amount of space, and yet somehow that information is
29:23
Speaker 1: communicated instantaneously. That's kind of the magic of it, right,
29:26
Speaker 1: it is the magic. And one thing I think to
29:28
Speaker 1: point out there is that the correlation is created locally.
29:32
Speaker 1: Like you talked about them making some arrangement. They were
29:35
Speaker 1: next to each other when they did that, right when
29:36
Speaker 1: they said, if I'm going to be blue, you got
29:38
Speaker 1: to be red. That was a local conversation. That was
29:41
Speaker 1: an agreement made with your neighbor, and then you separated
29:44
Speaker 1: the two particles. The correlation, however, was created locally. I
29:48
Speaker 1: think that's an important hint for like how this works
29:51
Speaker 1: in the universe, that these correlations are always created locally.
29:54
Speaker 1: All right, well, what is it a clue to like,
29:56
Speaker 1: how can you use this to maybe communicate faster than
29:58
Speaker 1: light or without RiPP playing the universe. The basic idea
30:01
Speaker 1: is to use these quantum probabilities to somehow communicate. So
30:05
Speaker 1: if you can like communicate via the quantum probabilities but
30:08
Speaker 1: not the actual waves, and so there's this ingenious experiment
30:12
Speaker 1: where you take photons and you split them in half,
30:15
Speaker 1: and if you look for this online is part of
30:16
Speaker 1: the quantum bomb detector experiment. But you don't need a bomb.
30:19
Speaker 1: I think that just makes it more confusing. So we're
30:21
Speaker 1: going to simplify it a little bit. But you have
30:23
Speaker 1: this beam of photons, and the first thing that happens
30:25
Speaker 1: is the beam. It's a beam splitter. This is like
30:28
Speaker 1: a mirror that's half silvered, and it splits part of
30:31
Speaker 1: the beam in one way and the other part of
30:33
Speaker 1: the beam the other way. The important thing to think
30:35
Speaker 1: about is what happens if you shoot one photon at
30:38
Speaker 1: this beam, it has a fifty percent chance of going
30:41
Speaker 1: one way and a fifty percent chance of going the
30:42
Speaker 1: other way. So, because this is a quantum mechanical object,
30:46
Speaker 1: if you're not looking at it, it it sort of does both.
30:48
Speaker 1: That has a probability to go left and a probability
30:51
Speaker 1: to go right. Okay, so now you have your beam
30:53
Speaker 1: and it's split into like two probabilistic halves. Now put
30:57
Speaker 1: some mirrors into the beam's come back together and read
31:00
Speaker 1: joined them again with a second beam splitter. So the
31:03
Speaker 1: second beam splitter can now sort of undo the splitting
31:06
Speaker 1: of the meat. So you have a beam of light
31:07
Speaker 1: which you split and then brought back together into a
31:10
Speaker 1: single beam. What's not like you actually split the beam.
31:13
Speaker 1: It's just that you give the photon two possibilities to go.
31:16
Speaker 1: You can go right or it can go left right
31:18
Speaker 1: exactly for an individual photon, it has possibilities to go
31:22
Speaker 1: left or to go right. And then later down the
31:24
Speaker 1: road you sort of bring those two possibilities together so
31:27
Speaker 1: that there's only that one photon. And this is like
31:29
Speaker 1: the double slit experiment. If you don't look to see
31:32
Speaker 1: which path of photon takes, then it has a probability
31:35
Speaker 1: to go left and the probability to go right. And
31:37
Speaker 1: those quantum waves do both right, and the quantum waves
31:40
Speaker 1: can do things like interfere with each other. So now
31:43
Speaker 1: there's a crucial step. When you bring these two photons
31:45
Speaker 1: back together. You make one path a tiny little bit longer,
31:48
Speaker 1: like a half wave length longer, so that they will
31:51
Speaker 1: interfere with each other, and just this one way. So
31:53
Speaker 1: the beam goes in a certain direction. So call that
31:55
Speaker 1: detector a You split the beam's probabilities, you bring them back,
31:58
Speaker 1: and you interfere them in this special way, so they
32:01
Speaker 1: will go in this certain direction. Detector A, so they
32:04
Speaker 1: have to interfere in just this way to hit this detector. Okay, Now,
32:07
Speaker 1: if there wasn't interference, if you like blocked one of
32:10
Speaker 1: the beam paths, then the light would have go on
32:12
Speaker 1: only one beam path. They would hit the beam splitter
32:14
Speaker 1: and it would either go left or right after that
32:16
Speaker 1: beam splitter. If two detectors, they're like A and B.
32:19
Speaker 1: A is what happens if you have both paths live
32:23
Speaker 1: because they interfere in just the right way, so they
32:25
Speaker 1: always go to A. But if one of them is blocked,
32:27
Speaker 1: then the photon has just hit the beam splitter and
32:29
Speaker 1: they can go either left or right at the end
32:32
Speaker 1: of the path. Okay, I think you're saying that I
32:34
Speaker 1: take a photon, I give it two possible paths to
32:37
Speaker 1: go on, and then I merged those paths, and so
32:40
Speaker 1: quantum mechanically, it's doing some weird quantum me kind of
32:42
Speaker 1: go things in the middle because it's sort of going
32:45
Speaker 1: or left and right at the same time. But then
32:47
Speaker 1: at the end you set up two ways to detect
32:49
Speaker 1: what happens either the two things merged together or one
32:53
Speaker 1: of those possibilities got blocked exactly, and if the two
32:56
Speaker 1: things merged together, then it goes to detector A. If
32:59
Speaker 1: one of them got blocked and only one of the
33:01
Speaker 1: possibilities is live, that half the time it goes to
33:03
Speaker 1: A and half the time it goes to BE. So
33:05
Speaker 1: the key thing is that it only goes to BE
33:08
Speaker 1: when there's one path live. If both paths are possible,
33:12
Speaker 1: it always goes to A. So if it goes to
33:14
Speaker 1: detector B, that means that only one path was possible, Okay,
33:17
Speaker 1: and very possible. You mean, like I put an obstruction
33:20
Speaker 1: in between one of the possibilities for this photon to
33:23
Speaker 1: go through. Exactly. So now put some device along one
33:26
Speaker 1: of the paths that you can control, some gate that
33:29
Speaker 1: you can close to block the possibility, right, So then
33:32
Speaker 1: what happens. So now the photon can't go along both
33:35
Speaker 1: paths simultaneously. It has to choose. This is just like
33:38
Speaker 1: in the double slit experiment. When you add a detector
33:40
Speaker 1: to one of the slits, it collapses the wave function.
33:43
Speaker 1: It doesn't allow it to maintain this uncertainty. It's like
33:46
Speaker 1: looking at the balls in the bags that we were
33:48
Speaker 1: talking about earlier. So now the photon has to either
33:51
Speaker 1: go on one path or the other. It has to
33:53
Speaker 1: go left or right at the first beam splitter. It
33:55
Speaker 1: can't maintain both possibilities. So either it goes into the obstacle, right,
34:00
Speaker 1: it hits your gate and it gets squashed and you
34:02
Speaker 1: don't get any beam on the other side. Right. That's
34:05
Speaker 1: one possibility. Another possibility is that it doesn't that it
34:08
Speaker 1: goes along the no obstacle path on the open path,
34:11
Speaker 1: and then when it gets to the end of the experiment,
34:13
Speaker 1: it either goes left or right into Detector A or B.
34:16
Speaker 1: The cool thing is that if it hits Detector B,
34:19
Speaker 1: that means that only one path was alive, because the
34:22
Speaker 1: only way it can get to detector B is if
34:24
Speaker 1: there is no interference both paths are alive. It always
34:27
Speaker 1: goes to Detector A only one path is alive, then
34:30
Speaker 1: half the time it goes to either one. So that's
34:32
Speaker 1: kind of cool because it means that if it hits
34:34
Speaker 1: Detector B, it went along the path that didn't have
34:37
Speaker 1: the obstacle. Okay, you kind of lost me a little
34:39
Speaker 1: bite a while back. So I have this set up right,
34:42
Speaker 1: and there's a both an obstacle and a device that
34:45
Speaker 1: I put it on on one of the paths or
34:47
Speaker 1: there's only one obstacle, and I control that obstacle. Yeah,
34:50
Speaker 1: you can control. It's like a gate that you can
34:51
Speaker 1: close or open. You can create an obstacle or you
34:54
Speaker 1: can remove it. Okay, If I'm blocking it, then the
34:57
Speaker 1: photon can only go through, for example, the left path,
35:02
Speaker 1: and if I open it, then it goes through both
35:04
Speaker 1: and I should get a different signal at the end. Exactly.
35:07
Speaker 1: If you open it, then you both possibilities like we
35:09
Speaker 1: talked about earlier, and the interfere in this way so
35:11
Speaker 1: that the beam always goes to detector A. But if
35:14
Speaker 1: I activate my obstacle and I block one side, then
35:17
Speaker 1: it can either go to A or B. Right, exactly,
35:20
Speaker 1: because it has to choose the left path or the
35:23
Speaker 1: right path. Now right, both possibilities are not allowed, and
35:26
Speaker 1: so it Ethan needs to decide am I hitting the
35:28
Speaker 1: obstacle or am I taking the other path? Just like
35:31
Speaker 1: in the double slit experiment, it can maintain the possibility
35:34
Speaker 1: of coming out of either slit as long as you
35:36
Speaker 1: don't look. In this experiment, now we're looking. By adding
35:39
Speaker 1: an obstacle, we're insisting that we know which path of
35:42
Speaker 1: photon went on, so it destroys this quantum mechanical possibility. Right,
35:46
Speaker 1: I'm blogging the right paths, and so now the photon
35:48
Speaker 1: it has to go through the left path if I
35:51
Speaker 1: receive it at the end exactly. So half the time
35:53
Speaker 1: you don't get any photon out because it hits the obstacle.
35:56
Speaker 1: The other half the time it does decide to go
35:58
Speaker 1: on the left path, and then it's the only beam
36:01
Speaker 1: that arrives at the second beam splitter, and so it
36:03
Speaker 1: goes fifty left and right because there's nothing else to
36:06
Speaker 1: interfere with it. Okay, So I set up this complicated experiment,
36:09
Speaker 1: and then what do I see? And what does that
36:12
Speaker 1: tell us about communicating without rippling? So if the obstacle
36:15
Speaker 1: is not there, you always see detector A. If the
36:18
Speaker 1: obstacle is there, then twenty five percent of the time
36:21
Speaker 1: you see the photon in detector B. And that's kind
36:24
Speaker 1: of cool because what that means is you can detect
36:27
Speaker 1: that the obstacle is there without sending a particle to it. Right,
36:31
Speaker 1: the photon only goes through the open path, the one
36:34
Speaker 1: that doesn't have the obstacle. So now I'm detecting that
36:37
Speaker 1: there's an obstacle along the right path by sending a
36:40
Speaker 1: photon along the left path, because now there's no possibility
36:44
Speaker 1: on the right path to do the quantum interference with
36:46
Speaker 1: the left half of the photon. Right. But it seems
36:49
Speaker 1: like then you're just communicating by blocking things, right. It's
36:52
Speaker 1: sort of like, you know, the reason that I see
36:55
Speaker 1: my head in front of me is because it's blocking
36:58
Speaker 1: the photons that are coming from the wall behind it.
37:00
Speaker 1: So isn't that also the same thing? It sounds sort
37:03
Speaker 1: of like the same thing, right. It sounds like saying, well,
37:05
Speaker 1: what if I just send two messengers and if one
37:07
Speaker 1: of them gets blocked, then I know that there's a
37:09
Speaker 1: block there. Right. But here we have not sent a
37:12
Speaker 1: photon along the other path. We've only sent the quantum
37:16
Speaker 1: mechanical possibility, right, And so it's different from the classical version.
37:20
Speaker 1: The classical version where you have like actual messengers, you
37:23
Speaker 1: have to send someone along both paths. Here we've sent
37:26
Speaker 1: the probability along both paths. We haven't actually sent a particle.
37:30
Speaker 1: The photon only goes along the open path. It doesn't
37:34
Speaker 1: go along this path. We know that it has to
37:37
Speaker 1: go along the open path. But wait, does this work
37:39
Speaker 1: with only one photon or do you have to send
37:41
Speaker 1: a bunch of photons. Now, this works with single photons,
37:44
Speaker 1: so you know which path the photon went. That one
37:47
Speaker 1: photon went on the open path and not on the
37:49
Speaker 1: blocked path. Then yet you know the obstacle is there,
37:52
Speaker 1: that the path is blocked because of where the photon
37:55
Speaker 1: ended up. But you only know that by taking a
37:57
Speaker 1: statistical survey right of photons you sent through. Any photon
38:00
Speaker 1: that arrives and detector B tells you that the obstacle
38:03
Speaker 1: is there. So you may need to send a few
38:05
Speaker 1: photons through your experiment to figure it out. I mean,
38:07
Speaker 1: it's it's sort of like random, right, Like if you
38:09
Speaker 1: send one photon and it goes through A doesn't tell
38:11
Speaker 1: you that there's an obstacle or not. That's right. It
38:14
Speaker 1: doesn't give you information. You have to keep going until
38:16
Speaker 1: you get one in the one that got blocked. That's true.
38:18
Speaker 1: But it's individual photons, right, It's not like a beam.
38:21
Speaker 1: It's not like the electromagnetic classical fields are interfering here.
38:24
Speaker 1: These are individual photons. It doesn't work every time, It
38:27
Speaker 1: only works of the time. But when you see a
38:30
Speaker 1: photon hit B, that means it didn't follow the blocked path.
38:34
Speaker 1: And that path has to be blocked. It's only one
38:37
Speaker 1: way for the photon to get to the second detector,
38:39
Speaker 1: and that's if the right hand path is blocked. The
38:42
Speaker 1: path it did not follow is blocked. Right, So you're
38:45
Speaker 1: saying that it communicates sort of without making a ripple,
38:48
Speaker 1: but only of the time, or this email only works
38:53
Speaker 1: of the time, which is more often than I get
38:54
Speaker 1: answers to emails sometimes anyway, But now imagine that you
38:58
Speaker 1: are controlling the obstacle and you're far away or something,
39:01
Speaker 1: and I can just look at the detectors. Now you
39:03
Speaker 1: can send me information by opening and closing the obstacle
39:06
Speaker 1: without us exchanging any photons or any kind of particle
39:10
Speaker 1: or any kind of ripple in any kind of field.
39:13
Speaker 1: Just the quantum mechanical probability of my photons going through
39:17
Speaker 1: your obstacle, or the lack of that probability is sending information.
39:21
Speaker 1: All right. Now we're getting into the practical application of
39:23
Speaker 1: sending a Q mail, and so let's get into the
39:26
Speaker 1: details of that arrangement and how it might work. But
39:28
Speaker 1: first let's take another quick break. All right, we're trying
39:43
Speaker 1: to send an email without leaving a ripple in the universe,
39:47
Speaker 1: and we have this arrangement of splitting photons, and one
39:50
Speaker 1: possibility of the photon goes one way and the other
39:52
Speaker 1: one maybe gets blocked. So how do I translate that
39:54
Speaker 1: into sending an email? Well, the first thing you'd want
39:56
Speaker 1: to do is do better than that. Doesn't seem like
39:59
Speaker 1: a very good bit rate to lose your information at
40:02
Speaker 1: the time. So people have come up with like meta
40:05
Speaker 1: versions of this. When you stack these on top of
40:07
Speaker 1: each other, so that if it goes to a have
40:09
Speaker 1: like another chance. But wait, how am I actually communicating
40:12
Speaker 1: through these? Like? Am I sending you the photon and
40:14
Speaker 1: then you're on the other side receiving the photons or what?
40:16
Speaker 1: You only control the gate. You only control whether the
40:19
Speaker 1: right hand path is blocked or not. So you want
40:22
Speaker 1: to send me some information, you close the gate or
40:24
Speaker 1: open it. I have like a morse quode button here
40:26
Speaker 1: that activates or deactivates the block the obstacle. And so
40:30
Speaker 1: where are you receiving this message? So I'm controlling the
40:33
Speaker 1: laser and the detectors, and we are not in communication
40:36
Speaker 1: in any other way. We're separated somehow, right, And so
40:41
Speaker 1: you can send me information. You can close the gate
40:43
Speaker 1: and we'll agree that. Like, I'm going to send ten
40:45
Speaker 1: of my photons through the experiment and see if I
40:47
Speaker 1: get any of them on B and then I'll know
40:49
Speaker 1: that the gate is closed. You and I do not
40:51
Speaker 1: have to talk to each other or communicating any other way,
40:54
Speaker 1: but I can tell whether or not you have closed
40:56
Speaker 1: the gate just by seeing if any photons arrive detector.
41:00
Speaker 1: B Oh. I see you're not talking about something at
41:03
Speaker 1: a distance, because we kind of have to be close
41:05
Speaker 1: to each other if I'm going to be pressing the
41:07
Speaker 1: button and blocking your stream of photons partially, right, that's right.
41:11
Speaker 1: I have to set up my experiment so that it's
41:13
Speaker 1: possible for my photons to go through your gate if
41:16
Speaker 1: it's open. Okay. So then and then you're at the
41:18
Speaker 1: end measuring what comes through this arrangement, and you're saying
41:22
Speaker 1: that if you get photons and one detector, then you
41:25
Speaker 1: don't know anything. But if you get it in the
41:27
Speaker 1: other detector, then you know that I activated my gate. Yeah, exactly,
41:31
Speaker 1: you closed your gate and shut down the quantum probabilities
41:35
Speaker 1: for one half of the beam. In that case, I
41:37
Speaker 1: know my photon didn't take your path because it went
41:40
Speaker 1: all the way through the experiment, so it didn't hit
41:42
Speaker 1: your obstacle, so I know which path it took, so
41:45
Speaker 1: I know that it didn't go through your obstacle. And
41:47
Speaker 1: yet I know something about your obstacle. I've learned something
41:50
Speaker 1: from your obstacle without sending any particles to you or
41:53
Speaker 1: getting any back from you. But I feel like some
41:56
Speaker 1: ripple has been made and you use particles to get
41:58
Speaker 1: this information, right, like you know, my my obstacle, what
42:02
Speaker 1: had to come into effect and had to act and exist, right,
42:07
Speaker 1: and some of the time it is going to be
42:08
Speaker 1: blocking the photon right from going through. So it feels
42:11
Speaker 1: like a very loyally kind of like, hey, we got magic,
42:14
Speaker 1: but only if you sort of look at it in
42:16
Speaker 1: this very narrow and then and technical way. But yes,
42:20
Speaker 1: but this is this our lawyers of the universe, right
42:22
Speaker 1: where like where's the loopole? The rule says we can't
42:24
Speaker 1: do exactly this, Let's see if we can accomplish it
42:26
Speaker 1: without actually doing that thing, And so yes, it's a
42:29
Speaker 1: half step forward. You know, we are definitely sending quantum
42:32
Speaker 1: mechanical probabilities in order to communicate. I'm sending the probability
42:37
Speaker 1: of a photon in your way the fact that doesn't
42:39
Speaker 1: make it through your gait and so it can't come
42:41
Speaker 1: back to interfere with the other. Probability is definitely how
42:45
Speaker 1: the information is being propagated. And yet it is true
42:48
Speaker 1: that we're not sending any actual particle or any actual field.
42:52
Speaker 1: We're only sending the probability of it. So yeah, it's
42:55
Speaker 1: a half step forward, but it's definitely not sending a
42:58
Speaker 1: message with particles or with yields themselves interesting And so
43:02
Speaker 1: what is is this an actual experiment that's been done
43:05
Speaker 1: and it works, or is this just a theoretical construction. No,
43:08
Speaker 1: people have done this and they've actually seen these results,
43:10
Speaker 1: and so we have accomplished this. We have sent information
43:13
Speaker 1: without communicating any particles. Are these photons are going through
43:17
Speaker 1: the non obstructed path and yet telling us whether or
43:20
Speaker 1: not the other path is obstructed? And people have built
43:23
Speaker 1: up on this. You can make this more robust by
43:25
Speaker 1: stacking a few of these on top of each other,
43:26
Speaker 1: having like multiple geats. Do you open them all at
43:29
Speaker 1: once or closed them all at once? So you can
43:31
Speaker 1: make it more robust. And there's a group in China
43:34
Speaker 1: that's been using this to send information to like demonstrate
43:37
Speaker 1: how to actually do this, so they can like send
43:40
Speaker 1: information from one computer to another computer without any actual
43:44
Speaker 1: messages passing back and forth. And they've actually done this.
43:48
Speaker 1: They sent a picture of a flower, I think it
43:50
Speaker 1: was from one computer to another computer. How good can
43:54
Speaker 1: you get with the stacking, Like you said, one photon,
43:57
Speaker 1: it's um one set up, it's accuracy. I guess how
44:03
Speaker 1: good can you get it? But it just depends on
44:04
Speaker 1: how many times you want to stack it. So the
44:06
Speaker 1: more versions of this experiment you have, the more opportunities
44:08
Speaker 1: you have to see that photon, and so you can
44:11
Speaker 1: get it essentially arbitrarily good if you string together, you know,
44:14
Speaker 1: a hundred or a thousand of these things. So people
44:16
Speaker 1: have some clever ideas for how to do that. But
44:18
Speaker 1: you know, people have done this experiment. They like communicated
44:21
Speaker 1: this picture from one computer to another without actually sending
44:25
Speaker 1: any particles. Now, there's a lot of controversy about this result.
44:28
Speaker 1: Some people feel like there's loopholes there. They don't quite
44:31
Speaker 1: believe the result that it's really solid. So it's not
44:34
Speaker 1: like this is conclusively demonstrated. The simple experiment with the
44:37
Speaker 1: single photon that's definitely been done and that agrees with
44:40
Speaker 1: the quantum mechanical predictions. The more sophisticated thing, where like
44:43
Speaker 1: are sending images from computer to computer without actually sending
44:47
Speaker 1: any particles. That's much more controversial, right, And I think
44:50
Speaker 1: it also maybe depends on what you mean philosophically by
44:53
Speaker 1: like causing a ripple in a universe or things not interacting, right,
44:57
Speaker 1: because things are definitely interacting here. There's just interacting in
45:00
Speaker 1: a quantum way, right. So you know, if I'm on
45:02
Speaker 1: the opposing council of this courtroom the universe, I might
45:05
Speaker 1: say like, yeah, you're still you know, you're still using physics.
45:08
Speaker 1: This is affecting then, and that is affecting this other thing,
45:11
Speaker 1: and so therefore you're still causing a ripple in the universe.
45:14
Speaker 1: And it opens up really interesting philosophical questions like is
45:18
Speaker 1: information physical is it quantum mechanical. A lot of people
45:22
Speaker 1: think that this whole quantum mechanical stuff is just abstract,
45:26
Speaker 1: that this wave function we're talking about, it's just like
45:28
Speaker 1: a calculation we do in our heads that helps us
45:31
Speaker 1: predict things, but the wave function itself is not real.
45:34
Speaker 1: But these kind of experiments support the other argument that
45:37
Speaker 1: the wave function itself is real and is out there
45:40
Speaker 1: and carries information on its own, because what we're doing
45:44
Speaker 1: here is not sending information via physical objects, right, actual photons,
45:48
Speaker 1: actual electrons, but the probability of them, right, just their
45:52
Speaker 1: quantum mechanical waves. So you're right, we're still sending information
45:56
Speaker 1: using the rules of the universe, and it's still propagating,
45:59
Speaker 1: but propagating in this probability space. And it's pretty bonkers
46:04
Speaker 1: to imagine that those are actually real in some philosophical sense, right,
46:08
Speaker 1: although you are still collapsing things, right, I mean, if
46:10
Speaker 1: you're sending ten twenty photons, if you're passing these through
46:14
Speaker 1: like a hundred of these gates, you're essentially kind of
46:17
Speaker 1: collapsing things right to measure them. It collapses the way
46:20
Speaker 1: function when you put the obstacle there, right, And that's
46:22
Speaker 1: how part of the information propagates. The fact that there
46:24
Speaker 1: is no quantum way of coming along on the right
46:26
Speaker 1: side to interfere with the left side is how you
46:29
Speaker 1: know the right side is blocked. But it's not a
46:31
Speaker 1: physical object that's being blocked. It's just the probability. It's
46:35
Speaker 1: not a classical object being blocked, is I think, is
46:37
Speaker 1: what you're saying. Yeah, it's not an observed quantity being blocked.
46:40
Speaker 1: It's just the probability, and that suggests that the probability
46:43
Speaker 1: itself is real in some way, like has the information
46:47
Speaker 1: And it's this deep question about information, like is information
46:49
Speaker 1: physical this idea we have that it has to like
46:52
Speaker 1: propagate locally from real objects to other real objects. Maybe
46:56
Speaker 1: it doesn't. Maybe information is quantum mechanical and can propagate
47:00
Speaker 1: through this like probability space, which again means like maybe
47:03
Speaker 1: the way function itself is real in some way, which
47:07
Speaker 1: is hard to grapple with because the wave function, you know,
47:09
Speaker 1: it's a complex number. You can have values like four
47:12
Speaker 1: plus two I and we don't think of these as
47:15
Speaker 1: real numbers. We don't call them real numbers because their
47:17
Speaker 1: imaginary numbers, because they're just like a calculation we do
47:20
Speaker 1: in our heads. But maybe they are real, right because
47:23
Speaker 1: we can use them to actually propagate information that doesn't
47:26
Speaker 1: appear in physical space. All right, Well, um, well what
47:29
Speaker 1: do you think this all means? And how soon are
47:31
Speaker 1: we gonna maybe see this in my iPhone? Well it's
47:34
Speaker 1: a very exciting development, and you know, it serves to
47:37
Speaker 1: like break down some of these barriers to tell us
47:39
Speaker 1: that something we thought was impossible is now possible. And
47:42
Speaker 1: it might feel like a technicality to you, but it's
47:45
Speaker 1: a crack in that door, opens it up, and maybe
47:48
Speaker 1: we can get our foot in there and then push
47:50
Speaker 1: it open and develop technologies that we thought were impossible,
47:53
Speaker 1: like sending messages between computers without actually connecting them in
47:57
Speaker 1: any way. All right, well, it sounds like stay too une.
48:00
Speaker 1: We might see this in the future or not or
48:03
Speaker 1: both at the same time. You hope you enjoyed that.
48:05
Speaker 1: Thanks for joining us, See you next time. Thanks for listening,
48:16
Speaker 1: and remember that Daniel and Jorge explained. The Universe is
48:19
Speaker 1: a production of I Heart Radio. For more podcast from
48:22
Speaker 1: my Heart Radio, visit the i heart Radio app, Apple Podcasts,
48:26
Speaker 1: or wherever you listen to your favorite shows. H