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

Episode Date: November 8, 2022

Daniel and Jorge talk about ingenious quantum tricks to send information without actual particles.See omnystudio.com/listener for privacy information.

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On the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want or gone. Hold up. Isn't that against school policy? That seems inappropriate.

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I'm bikes the other day, and we're like, we're like, people ride bikes because it's fun. We got more incredible guests like Megan in store, plus news of the day and more. So make sure you listen to Good Game with Sarah Spain on the IHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Brought to you by Novartis, founding partner of IHeart Women's Sports Network. Hey, Jorge, did you get the outline I sent you for this episode? I did. Why? Well, I didn't hear back from you about it. Oh, well, I guess you should only worry if you do hear back from me.

Oh, that's right. I forgot. No reply also means something. Yeah, you know, it means it's all good. Or it means I didn't see your email or maybe it means I'll just reply later. Sounds like a superposition of quantum possibilities. That's right. Yes. I believe in Qmail, not email. I hope you don't get entangled with your inbox. Yeah, my hymn box is a pretty big quantum mess, to be honest. Maybe one day it'll collapse.

Well, you know what they say? I like to wave at my emails as they fly by. I wonder if Schrodinger got email. He did and he didn't, right? Hi, I'm Jorge, my cartoonist, and the co-author of Frequently Asked Questions about the universe. Hi, I'm Daniel. I'm a particle physicist and a professor at UC Irvine,

and I'm going to do my best not to spend most of this podcast chuckling. Yeah, you should be explaining things, Daniel, not laughing. Well, we got an email from a listener this morning complaining that the chuckle time on the podcast has been going up. Oh, really? Am I getting too funny? Is that what you're saying? Or are you laughing at your own jokes? I'm not sure.

Just too much chuckling overall. More content, less chuckling. I see. More physics. less humor. Yeah, exactly. Stop the spontaneous expressions of fun, please. Boy, you can't please everybody all the time. Well, we'll try to be more serious about it. We'll try, but we'll probably fail. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of iHeart Radio. In which we try to be serious about questions

of the universe and have fun while doing it. We ask the biggest, deepest questions about how everything out there works. What in the end are the fundamental rules of reality? Why is it even possible for us to understand them? Or is it? Can we import the rules of the universe into our minds so that they actually make sense to us? On this podcast, we push against that frontier and try to make sure that you understand everything that humans do and do not know about the universe. That's right, because what could be more fun than exploring this humongous and complex and complicated and amazing universe? And what could be more chuckleworthy than thinking that us humans can one day understand all of it.

It does seem sometimes like the universe is playing a big joke on us. It's like, oh, it seems to work this way. F equals M.A. is totally right. No, actually, we were lying. It's a completely different set of rules. Wait, are you saying quantum mechanics? It's just the big punchline. The whole thing is a sci-op, man.

The universe is trying to psych us out. Let's see what we can get these humans to believe, crazy stuff like true randomness. Well, you know, we are part of the universe. Does that mean we're playing a joke on ourselves? I suppose so. Yes, we are sciopping ourselves. I mean, we're the joke, Daniel. You want to say, if you're the only one who doesn't get the joke, the joke's on you. As long as I get to hear the secrets of the universe, I'm happy if somebody laughs at me at the same time.

But it is an interesting and sometimes funny universe because it is so weird, especially quantum mechanics. This is weird, theory about the universe. It says that things are truly random and that sometimes there are multiple things that are true at the same time. It is really amazing that we can spend thousands of years to, developing an intuition for how the universe works and then a few hundred years describing it mathematically only to discover that at its core at a deeper level the rules of the universe are completely different totally foreign to us maybe even alien and yet those alien rules somehow weave themselves together so that at our scale and our experience they act in the way that's intuitive to us it's incredible that at different scales the universe seems to follow these totally different sets of laws incongruent ideas about the very nature of space and time and information, and yet they weave themselves together at the interface. It's incredible.

Yeah, are you saying quantum mechanics is just a tiny little joke? Or it's only funny in small places? It's like 10 to the 26 tiny jokes, which all add up to one hilarious chuckle. To one average bland experience of the universe. Exactly, until the universe collapses on the weight of its own puns. But quantum mechanics says the universe gets really weird at the very smallest scales, which maybe you don't think affects you on an everyday basis.

but it actually does, you know, most of our electronics and a lot of our communications and all of our devices. They all sort of are dependent on our knowledge of quantum mechanics. And as we try to understand the way that the universe works, we tend to revert to this microscopic picture. When we say we want to understand the universe, some of us feel like we want to tear it apart into the tiny little pieces, figure out what are the rules of those little pieces? How do they interact? And then how do you zoom back out to get the picture of the universe that we're familiar with? And so often in quantum mechanics, we are thinking about little particles, tiny little quantum objects,

and what are the rules for those things? Do they fly through space the way baseball does, or do they appear just in snapshots? How do they communicate information back and forth? And how does that change how we can communicate up here at the big, slow human scale? That's right, because if quantum mechanics does let you do some weird things that we didn't think about before, it might change the way that we can maybe make devices or allow us to communicate between different points. on Earth. Exactly.

If the rules of quantum mechanics really are strange, alien to our intuition, then maybe we can make quantum mechanics do things at our scale that are very weird that we once thought might be impossible. Coming to the Apple store soon? Alien iPhones. Is that what you're saying? Excuse my long chuckle there. That was pretty funny.

Well, I'm sorry. Man, we're going to get a lot of complaints. Stop laughing, Daniel. Dang it, the chuckle time is just increasing the first rule. of chuckle time is don't talk about chuckle time. It just makes more chuckle time. That's right. But usually talking about the joke kills the joke. We've collapsed it again. And so quantum mechanics may open some interesting possibilities for future technologies. And so on the podcast today, we'll be tackling the question.

Can you send messages without particles? Is that like sending emails without replies? That happens all the time, actually. But this has to do more with how information propagates in a quantum universe. We like to think about everything happening in terms of the microscopic particles, and usually that picture involves local interactions, meaning like one particle pushes against another particle, which pushes against another. I think about how electricity flows. You can think about just flowing down the wire, but if you zoom into the particles, it's one electron jumping from spot to spot and pushing other electrons. You can build up this idea of

electricity from the little microscopic particles and how they touch each other. Usually this is this crucial bit where they need to be near each other where everything has to be local. Is that kind of like how my wife communicates a lot to me just by giving me certain looks? I think that's actually telepathic, man. I think that might break the laws of physics. Usually they're not good messages. I don't know if we should be doing marriage therapy on the podcast. We already have too many chuckles. Well, yeah, because, you know, no marriage needs more chuckles. Every marriage needs more chuckles, man. Humor is the best therapy. That depends on what the people are trickling at.

You got to take your wife seriously, that's for sure. But yeah, usually communication involves some sort of interaction between particles, right? Even if you're just giving somebody a look to communicate something to them, you're exchanging photons, right? That's right. Our picture of how we communicate involves sending particles or waves through fields, which you can also think of as particles. But everything involves somehow wiggling a field or sending a particle, using that to communicate information. Yeah, because I guess, you know, in the universe, we have a certain speed of light, right? A speed of information.

Like, you can't somehow, it seems, move things from one place to another without going faster than the speed of light. That's right. It's pretty hard-coded into special relativity that no information can move faster than the speed of light. And even quantum mechanics, which does really weird things, doesn't violate that rule. Although, sometimes it seems like it might. And so I guess the question here is, can you somehow communicate? communicate, send messages, interact between two places in the universe without actually exchanging a particle or a wiggle in some kind of particle field. Exactly. Could you somehow send a message to your buddy on Alpha Centauri without having to shoot him an electron or a beam of photons or some other kind of particle or wave-based information?

Sounds like we're asking, does magic exist, you know? Quantum mechanics feels like magic sometimes. You know, it does things that we think are. You know, an electron can be here and then it can be there without going in between. Even if sometimes the spot in between is impossible for the electron to be in. You can have an electron appear on one side and then the other side of an infinite barrier. It's crazy. That seems like magic. And yet we see it happen in our universe.

Would you describe it as magic though? Or is it maybe like scientific magic? Because you can maybe, you know, statistically predict what's going to happen. Yeah, it's only magic until we explain it. then it's science again. Then it's not magical. Science has been ruining the magic of the universe for hundreds of years. Well, as usual, we were wondering how many people had thought about this question

or think it's possible to maybe send messages without using particle or particle fields. So thank you very much to our cadre of volunteers who answer these questions without any preparation to give us a sense for what people are thinking about and to give you a sense what everyone else out there is thinking. If you'd like to participate for future episodes of the podcast, especially if you've never done so before and you're a long time listener, please do reach out. Our email address is Questions at Danielanhorpe.com. So think about it for a second. Do you think it's possible in this universe to send a message without using particles? Here's what people had to say.

I think no, you can't. Well, oh, no, no, no, because of like quantum computers and quantum entanglement. So theoretically, if we have two quantumly entangled particles, we could send information and thus send a message between those two particles without sending particles from one location to another. When I'm thinking about these questions, actually I'm thinking about quantum entanglement, how you can send information from one point to another faster than a speed of light. Scientists hope this will be it like quantum entanglement, but I don't know too many information right now. I don't think no. I don't think that's possible. I think maybe the closest thing to sending

information without particles that we currently looking at is gravitational waves, but then, yeah, how's that possible? I think that that's just a shift in gravitons. So, no, I don't think so. I think the only way to send a message without sending any particles might be through quantum entanglement, but I'm not even sure if that counts, since I'm pretty sure we can't affect the state of the entangled particles. We can just observe them. So I'm not sure we could actually pass a message through that. That depends on what you mean by particles. If you mean fermions, then yes, you can send a message without using particles because photons can carry information. But if you mean any particle, if you include photons, then you can't, because I think

you need some entity like a photon that carries energy to transfer information? Well, everything in the universe is obviously made of particles, so I'm not really sure how you would be able to send any message without them. But I'm also thinking maybe you could send a message with a lack of particles. So say someone's on the moon and you make a really big shadow with your hand in a really powerful light. And that person on the moon knows that when the shadow passes over them, that means X or Y. And I guess technically that would be sending a message with a lack of particles, if that makes any sense. But otherwise, I don't see any other way. All right. Not a lot of optimism. Most people are like,

a few mentions of quantum entanglement. Yeah, we have a pretty educated listener crowd on physics. A few people said quantum entanglement. Yeah, and quantum entangling is sort of the right direction to think about because that's the non-local part of quantum mechanics. The fact that things can happen in a correlated way across space, even if things are causally separated. So that's definitely the right direction to be thinking about. Right. And somebody tried to make a distinction between like different kinds of particles, right? Because there are some matter particles like the stuff we're made out of.

And then there are other particles which, you know, are more intangible. Exactly. In the end, we can think about all of those as particles or you can think about all of them as fields. In theoretical particle physics, there's sort of this argument about whether fields or particles are the most basic thing in the universe. But fundamentally, we're all talking about the same kind of stuff. Like, can you send a message without a field at all or disturbing any fields?

Well, you know, some people think that fields don't even exist. The fields are just like a mathematical construct in our minds. That particles are the only real thing because you don't ever see fields, right? You can't interact with a field except for seeing its effect on a particle. So some people don't even think fields are real, that everything is just particles. But then those people are just imaginary too. so there was even a guy who developed a version of physics without fields and even without numbers what ironically his last name was fields ironic i think you're going to say ironically his name was whiteson no heart tree

fields is a philosopher of physics and he wrote a book called science without numbers in which he argues that fields are just a made up thing and you don't need them at all of course he thinks he's real you know he's a field and he just wanted to be the only field in the universe the field field but yeah this is this an interesting question. Can you communicate without particles? And so let's dig into it, Daniel. Let's start with, first of all, messaging with particles. How does that work? How do we usually send information? So almost all the information that we transmit uses either particles or waves. And really, those two are equivalent. You can think of every particle as a wave in some quantum field, or if you like, you can think of quantum fields as just like an infinite sum of possible

particles. It's all really fundamentally equivalent. You know, when you send an email, for example, Well, what are you doing? You're sending a message along some wires, and those messages are wiggles in those little fields. You send a beam of light at somebody, right? Your friend across the street has an open window and you're turning your flashlight on and off, then you are sending beams of photons,

which you can think of either as ripples in the electromagnetic field of the universe or little packets, little particles that are flying through space. Either way, you're transmitting that information through particles and fields. Right. Even when you talk on your cell phone out there, you're using light as well, right? Like your cell phone is transmitting light at a really high frequency that you can't see, but it's light, right? And then the cell phone antenna and towers out there are also communicating with your cell phone through light. Exactly. And you even have transformation of information there because the neural pulses go through your mind and those are electrical pulses.

And then your mouth transforms them into sound waves, which is just shaking of the air. Then the microphone in your cell phone translates them back into a different kind of electrical pulses, which then get emitted by your phone as electromagnetic pulses, because that's just another kind of photon, one with very long frequency. And in all of those steps, we have a microphysical picture of what's going on, atoms pushing against other atoms or photons flying through the electromagnetic fields that fill the whole universe. It's always local. It's always like one thing pushing another thing.

It's like a Rube Goldberg machine, right? everything is coming into sort of effective contact with something else. Right. And even your voice uses the electromagnetic radiation and forces, right? Like when the air particles are pushing against each other, they're pushing against each other using the electromagnetic force, which means they're also exchanging photons, right? Yeah, that's exactly right. The reason that air particles don't pass through each other, they can't occupy the same space, it primarily because their electrons bump against each other.

They resist and repel. And you're right, that's done either through electromagnetic, fields or virtual photons depending on the picture that you prefer but all that stuff requires some sort of passage of wiggles in fields or particles yeah even your voice is light pure light kind of right even when i'm talking about heavy topics or illuminating topics as well or chuckling too your chuckles are made of pure light as well daniel and light is really one of our primary ways to interact in the universe when stars send us light from across vast distances of space those are also photons. It's created a particle which is shot out from the surface of that sun and then flown

through many megaparsecs before it hits your eyeball. That information that the star exists and what its temperature is and where it is comes along with the photon. Yeah, and that's not the only particle we get information from in from the universe, right? We also get lots of other particles coming at us and telling us things about the universe. Yeah, now we have multi-messinger astronomy, which means that we can see things out there in the universe, not just using photons. So for example, we can see other particles. Protons hit the atmosphere at very high speed. Some of them are generated by the sun. Some of them come from outside the solar system. These things we call cosmic rays can carry a lot of information about what's going on out there in the galaxy. So that's definitely not a photon,

right? A proton is a matter particle. It's made out of quarks, which each are ripples in the quark fields that fill the universe. But just like a photon is a ripple in the electromagnetic field, these quarks are ripples in the cork fields and they carry information exactly the same way that a photon does. Right. But then there are gravitational waves though, right? Those are sort of information we're gaining about the universe, something communicating something to us, but do we know if there are particles? Yeah, that's a great question. And there's a lot of confusion about gravitational waves versus gravitons. So gravitational waves happen anytime anything in the universe with mass accelerates.

Like if two black holes fall into each other, the acceleration as they fall in, they're circling around each other, generates gravitational waves, really big gravitational waves that we can detect. And this is a prediction of general relativity, which is a non-quantum theory. It's a classical theory. It says that space and time are continuous and everything has a smooth path, really in conflict with our quantum view of the universe. But we see it. We see these things happening. We see these ripples in space and time. These are gravitational waves. And they're classical objects. But, you know, there are waves in a field and they carry information and move at the speed of light, which is kind of awesome. We don't know if they're made of gravitons. It might be that gravity is in the end a quantum field theory like the other forces. And you can describe it in terms of tiny little packets. But those packets, if they exist, they're too small for us to see. We're just barely able to eat.

even see gravitational waves. One gravitational wave might be made out of an enormous number of tiny gravitons so small that we can't resolve them. The way like a wave in the ocean is made of lots of droplets, but we can't separate them necessarily. Wait, so then if gravitational waves are not made out of particles, and we've answered the question of the episode, you could send the message using gravitational waves without particles.

Yeah, I suppose so you could send information without particles if gravity is not a quantum theory, but you'd still be sending information via waves. And in the end, particles and waves, really, what's the difference? They're just two attempts by the human mind to describe something about the universe, which in the end is unfamiliar. You know, physics is the effort to describe the unfamiliar in terms of the familiar. And the reason we have an argument about whether to describe these things in terms of particles or fields or waves is because none of those are really the right description. They're just sort of like our attempt to capture them in terms of something we know. Like when you drink a really tasty glass of wine and you're like, hmm, it's like vanilla and notes of oak or whatever. Now, those aren't really there in the wine. Just your efforts to describe them in terms of a language you know. It sounds like you're trying to get out of something out there, Daniel. But I think what you're saying is that, you know, it's kind of hard to imagine communicating something across a distance in this universe without creating some sort of ripple that, you know, moves through space. I think that's what you're saying. And gravitational waves are technically ripples.

through some sort of medium or some sort of field in the universe. And so the question then maybe is, like, can you actually communicate without causing any ripples in the universe? Yeah, we think about information as propagating through the universe. We think of everything is local. Something passes a note to the next thing, which passes a note to the next thing. You can't just have information appear somewhere far away.

We think we have this intuition that the universe seems to be local, that information moves and propagates. So that to send information, you've got to create some sort of ripple, in a field. And think about really what a wave is. Like if you think about a guitar string with a wave on it, why does it wave anyway? It waves because one bit of the string is then wiggling the next bit, which is wiggling the next bit, which is wiggling the next bit. Information about the wave is flowing down the string. The same way like you're driving down the freeway, why is everybody

in front of you breaking? Because the person in front of them is breaking, because their information is local. They just respond to the person in front of them. So the whole idea of a wave is sort of comes out of information being local and propagating locally. Right. All right. Well, it seems kind of impossible to maybe communicate or send information across the universe without causing any kind of a ripple. But let's see if that is actually true.

And so let's get into how we might be able to do that. But first, let's take a quick break. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal glass. The injured were being loaded into ambulances. Just a chaotic, chaotic scene.

In its wake, a new kind of enemy emerged, and it was here to see. Day. Terrorism. Law and order criminal justice system is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly. Now I'm seriously suspicious.

Well, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone. Now, hold up. Isn't that against school policy?

That sounds totally inappropriate. Well, according to this person, this is her boyfriend's former professor and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them. I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not?

To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. I always have to be so good, no one could ignore me. Carve my path with data and drive. But some people only see who I am on paper. The paper ceiling. The limitations from degree screens to stereotypes that are holding back over 70 million stars. Workers skilled through alternative routes rather than a bachelor's degree.

It's time for skills to speak for themselves. Find resources for breaking through barriers at tetherpapersealing.org. Brought to you by Opportunity at Work and the Ad Council. All right, we're trying to send, I guess, Q-mail. messages without causing a ripple in the universe? What are you trying to do here? Then you're trying to send messages without anybody finding out? I think it would be pretty awesome to be able to send information without creating any ripples or sending any particles. It used to be something new that we didn't think was possible before. It might open up new technologies that we can't even imagine

today because it would like break down one of our basic intuitions about how the universe works. You know, we're pretty sure that we're pretty wrong about some of these assumptions about the universe, things we've assumed for a long, long time. One of them probably has to go. We just don't really know which yet. Yeah, I'm sure there are many politicians who would love to have the technology to send text messages without leaving a trace or a ripple through anything. Wow, you went straight for the cynical applications, huh?

Well, those usually come first. We're thinking about how to pitch this to Facebook next, right? Well, I'm sure they're on it. They don't waste time chuckling about these things. But I think you were saying earlier how physicists sort of look at the universe and how things interact in it as being local or non-local. So local just kind of means that you can't affect something that's really far away from you, kind of, right?

Like the universe seems to have a sort of a short range of things. If I want to communicate something to you, I have to do it through a series of intermediary particles or things like that, right? Or fields. Exactly. Have your people talk to my people. That's how these things get done. On the other hand, we also know that quantum mechanics has some very strange, very non-local

features to it. It seems to be able to do things across space time that sounds sort of impossible. Yeah. And so that's maybe the question we're asking here today is can we exploit? Can we use some of this weird quantum mechanical magic to maybe send messages without causing a ripple in any of the quantum fields? And we heard several of our listeners suggest maybe using quantum entanglement, which is a great idea because quantum entanglement really highlights the non-local nature of quantum mechanics. You know, so very briefly, the idea of entanglement is you have two particles that are somehow connected. You know something about them. Like, if one is spin up, the other one has to be spit down because of the way they were created.

You know, or imagine you have two balls and you know that only one of them can be red and the other one has to be blue. But maybe you don't know which is which. So quantum entanglement says, you have these two particles. You know something about them overall that makes them have like opposite states or different colors or something. But you don't know which is which. They just have to be in the opposite states. And quantum mechanics says that they can stay uncertain, that you can have one particle have a possibility of being up and the possibility of being down. And the other particle also maintain both of those possibilities.

That take these two particles and pull them really far apart, a kilometer, 10 kilometers, a thousand kilometers, whatever, they can maintain those possibilities. Now, if you look at the first particle and you say, oh, it's up, that means that the other particle, even though it's super duper far away and there's no time for information to get to it, all of a sudden goes from having both possibilities to having to be down because the first one was up the second one has to be down you know that because of how they were created so quantum entanglement definitely is a weird non-local part of quantum mechanics i guess that's the confusing part about this whole entanglement thing right it's that like if you would think that if i had two balls one red and one blue and i put him in a bag and i mix them up then i take one out without looking at it and i drive it over to the other side of the country obviously if i see that it's red and the one that stayed behind is going to be blue or if I look to the one over there and it's blue,

then this one has to be red. That sort of seems obvious. But I guess the tricky thing about quantum mechanics is that they're not balls, right? They're quantum mechanical objects. Like when you separate the two balls, it's not like one of them is red and you just don't see it. It's like they're both, both red and blue at the same time in quantum mechanics. They're both actually undetermined, right? The universe hasn't decided which one is red and which one is blue. This is whole beautiful series of experiments, Bell's experiments, that ask the question, has the universe actually decided in advance? Is it really determined and we just don't know the answer? Or is it actually undetermined the whole time? And we'll have a whole episode about Bell's

experiments soon. But those experiments determine that there's no local hidden variables. There's no information that's traveling along with those particles that somehow determines which one is red and which one is blue. That you have some sort of non-local effect there. Either they're communicating somehow or there's some sort of like gloatical. global plan that affects everything. Right. And I guess from a layperson point of view, like, it's hard to swallow. You know, like, I would think like, hey, it's not that the ball is red and blue.

It's just you just don't know what it is. But inside the bag, the ball knows if it's red or blue, right? That's our intuition because that's the way our world works, right? We think that there's a truth that everything is determined. We just don't have all the information. But quantum mechanics really does seem to operate differently. It really does seem to follow very different rules. That's what I was talking about earlier, that there are these weird, strange, almost alien ideas about how the universe works, which really fly in the face of the things that we expect it to do.

And maybe that would let us build on those properties to do crazy bonkers things we thought were impossible. You know, whenever we talk about entanglement on the podcast, I get a few emails from folks who ask, isn't it possible to use entanglement somehow to communicate faster than light? Because it seems like there's this faster than light process here. You're looking at one of the particles to deciding whether it's up or down. Somehow the other one instantaneously goes from undetermined to determined, either up or down. So several listeners have emailed me with a scheme trying to use this to send information faster than light. By, for example, collapsing one particle and noticing on the other end that the particle is collapsed, using that to send information somehow. Unfortunately, that doesn't work because you can't tell whether your particle's wave function is collapsed.

You can just measure it. You can say, oh, mine is red or blue. You can't tell whether the other person has measured their particle or not. So as far as we know, there's no way to use this to send information faster than light. However, it does seem like there is something non-local going on. So maybe we just need to be more clever about it. Right. I wonder maybe an interesting analogy to flesh out here is like instead of having balls that

are painted blue and red, maybe they're like transparent balls and they have a little LED lights inside of them that turn red or blue. And so when you put them together inside of the bag, they somehow make the arrangement that if one of them is going to turn blue, the other one turns red. And if the other one turns red, the other one's going to turn blue. They make that arrangement. And then you take the balls and you separate them and you take one to the other side of the country and you keep one of them.

Now, I think the magic sort of happens if I look at the one I have here and it turns blue, somehow the one on the other side of the country has to know. to turn red, but they're separated by a huge amount of space, and yet somehow that information is communicated instantaneously. That's kind of the magic of it, right? It is the magic. And one thing I think to point out there is that the correlation is created locally. You talked about them making some arrangement. They were next to each other when they did that, right? When they said, if I'm going to be blue, you got to be red. That was a local conversation. That was an agreement made with your neighbor. And then you separated the two particles. The correlation, however, was

created locally. I think that's an important hint for like how this works in the universe, that these correlations are always created locally. All right. Well, what is it a clue too? Like, how can you use this to maybe communicate faster than light or without rippling the universe? The basic idea is to use these quantum probabilities to somehow communicate. So if you can like communicate via the quantum probabilities, but not the actual waves. And so there's this ingenious experiment where you take photons and you split them in half. And if you look for this online, it's part of the quantum bomb detector experiment, but you don't need a bomb. I think that just makes it more confusing, so we're going to simplify it a little bit. But you have this beam of photons. And the first thing that

happens is the beam, it's a beam splitter. So this is like a mirror that's half silvered and it splits part of the beam in one way and the other part of the beam the other way. The important thing to think about is what happens if you shoot one photon at this beam. It has a 50% chance of going one way and a 50% chance of going the other way. So because this is a quantum mechanical object, if you're not Looking at it, it sort of does both. It has a probability to go left and a probability to go right. So now you have your beam and it's split into like two probabilistic halves. Now put some mirrors in so the beams come back together and rejoin them again with a second beam splitter.

So the second beam splitter can now sort of undo the splitting of the beam. So you have a beam of light which you split and then brought back together into a single beam. What's not like you actually split the beam is just that you give the photon two possibilities to go. it can go right or it can go left, right? Exactly. For an individual photon, it has possibilities to go left or to go right. And then later down the road, you sort of bring those two possibilities together so that there's only that one photon.

And this is like the double slit experiment. If you don't look to see which path the photon takes, then it has a probability to go left and a probability to go right. And those quantum waves do both, right? And the quantum waves can do things like interfere with each other. So now there's a crucial step when you bring these two photons back together, you make one path a tiny little bit longer like a half wavelength longer so that they'll interfere with each other in just this one way so the beam goes in a certain direction so call that detector a you split

the beam's probabilities you bring them back and you interfere them in this special way so they'll go in this certain direction detector a so they have to interfere in just this way to hit this detector okay now if there wasn't interference if you like blocked one of the beam paths then the light would go on only one beam path they would hit the beam splitter and it would either go left or right after that beam splitter. So you have two detectors there like A and B. A is what happens if you have both paths live because they interfere in just the right way so they always go to A. But if one of them is blocked, then the photons just hit the beam splitter and they can go either left or right at the end of the path. Okay, I think you were saying that I take a photon, I give it two possible

paths to go on, and then I merge those paths. And so quantum mechanically, it's doing some weird quantum mechanical things in the middle because it's sort of going left and right at the same time. But then at the end, you set up two ways to detect what happens, either the two things merged together or one of those possibilities got blocked. Exactly. And if the two things merged together, then it goes to detector A. If one of them got blocked and only one of the possibilities is live, that half the time it goes to A and half the time it goes to B. So the key thing is that it only goes to B when there's one path live. If both paths are possible, it always goes to A. So if it goes to Detector B, that means that only one path was possible.

Okay, and by possible, you mean like I put an obstruction in between one of the possibilities for this photon to go through? Exactly. So now put some device along one of the paths that you can control, some gate that you can close to block the possibility, right? So then what happens? So now the photon can't go along both paths simultaneously. It has to choose.

This is just like in the double slit experiment when you add a detector to one of the slits. It collapses the wave function. It doesn't allow it to maintain this uncertainty. It's like looking at the balls in the bags that we were talking about earlier. So now the photon has to either go on one path or the other. It has to go left or right at the first beam splitter. It can't maintain both possibilities. So either it goes into the obstacle, right?

It hits your gate and it gets squashed and you don't get any beam on the other side. Right. That's one possibility. Another possibility is that it doesn't, that it goes along the no obstacle path, the open path. And then when it gets to the end of the experience, it either goes left or right into detector A or B. The cool thing is that if it hits detector B, that means that only one path was alive

because the only way it can get to detector B is if there is no interference. Both paths are alive, it always goes to detector A. If only one path is alive, then half the time it goes to either one. So that's kind of cool because it means that if it hits detector B, it went along the path that didn't have the obstacle.

Okay, you kind of lost me a little while back. So I have this setup, right? and there's both an obstacle and a device that I put it on on one of the paths or there's only one obstacle and I control that obstacle. Yeah, you can control. It's like a gate that you can close or open. You can create an obstacle or you can remove it.

Okay. If I'm blocking it, then the photon can only go through, for example, the left path. And if I open it, then it goes through both and I should get a different signal at the end. Exactly. If you open it, then you have both possibilities like we talked about earlier and they interfere in this way

so the beam always goes to detector A. But if I activate my obstacle and I block one side, then it can either go to A or B, right? Exactly, because it has to choose the left path or the right path now, right? Both possibilities are not allowed. And so it either needs to decide, am I hitting the obstacle or am I taking the other path? Just like in the double slit experiment, it can maintain the possibility of coming out of either slit as long as you don't look.

In this experiment, now we're looking by adding an obstacle. We're insisting that we know which path. half the photon went on. So it destroys this quantum mechanical possibility. Right. I'm blocking the right path. And so now the photon has to go through the left path if I receive it at the end. Exactly. So half the time, you don't get any photon out because it hits the obstacle. The other half the time, it does decide to go on the left path. And then it's the only beam that arrives at the second beam splitter. And so it goes 50% left and 50% right, because there's nothing else to interfere with it. Okay. So I set up this complicated experiment.

And then what do I see? And what does that tell us about communicating without rippling? So if the obstacle is not there, you always see detector A. If the obstacle is there, then 25% of the time you see the photon in detector B. And that's kind of cool because what that means is you can detect that the obstacle is there without sending a particle to it. Right? The photon only goes through the open path, the one that doesn't have the obstacle. So now I'm detecting that there's an obstacle along the right path.

by sending a photon along the left path, because now there's no possibility on the right path to do the quantum interference with the left half of the photon. Right, but it seems like then you're just communicating by blocking things, right? Sort of like, you know, the reason that I see my hand in front of me is because it's blocking the photons

that are coming from the wall behind it. So isn't that also the same thing? It sounds sort of like the same thing, right? It sounds like saying, well, what if I just send two messengers and if one of them gets blocked, that I know that there's a block there, right? But here we have not sent a photon along the other path. We've only sent the quantum mechanical possibility, right?

And so it's different from the classical version. The classical version, or we have like actual messengers, you have to send someone along both paths. Here we've sent the probability along both paths. We haven't actually sent a particle. The photon only goes along the open path. It doesn't go along this path. We know that it has to go along the open path.

Wait, does this work with only one photon or do you have to send a bunch of photons? No, this works with single photons. So you know which path the photon went. That one photon went on the open path and not on the blocked path. And yet you know the obstacle is there, that the path is blocked because of where the photon ended up. But you only know that by taking a statistical survey, right, of photons you send through. Any photon that arrives in Detector B tells you that the obstacle is there. So you may need to send a few photons through your experiment to figure it out.

I mean, it's sort of like random, right? Like, if you send one photon and it goes through A, it doesn't tell you that there's a obstacle or not. That's right. A doesn't give you information. You have to keep going until you get one in the one that got blocked. That's true, but it's individual photons, right? It's not like a beam. It's not like the electromagnetic classical fields are interfering here.

These are individual photons. It doesn't work every time. It only works 25% of the time. But when you see a photon hit B, that means it didn't follow the blocked path and that path has to be blocked. It's only one way for the photon to get to the second detector, and that's if the right-hand path is blocked. The path it did not follow is blocked. Right. So you're saying that it communicates sort of without making a ripple, but only 25% of the time.

Or this email only works 25% of the time. Which is more often than I get answers to email sometimes anyway. But now imagine that you are controlling the obstacle and you're far away or something, and I can just look at the detectors. Now you can send me information by opening and closing the obstacle. without us exchanging any photons or any kind of particle or any kind of ripple in any kind of field. Just the quantum mechanical probability of my photons going through your obstacle or the lack of that probability is sending information. All right.

Now we're getting into the practical application of sending Q mail. And so let's get into the details of that arrangement and how it might work. But first, let's take another quick break. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, at 6.33 p.m., everything changed. There's been a bombing at the TWA terminal. Apparently, the explosion actually impelled metal, glass.

The injured were being loaded into ambulances, just to catch. chaotic, chaotic scene. In its wake, a new kind of enemy emerged, and it was here to stay. Terrorism. Law and Order Criminal Justice System is back. In season two, we're turning our focus to a threat that hides in plain sight. That's harder to predict and even harder to stop. Listen to the new season of Law and Order Criminal Justice System

on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Oh, wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend has been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now, he's insisting we get to know each other, but I just want her gone.

Now, hold up. Isn't that against school policy? That sounds totally inappropriate. Well, according to this person, this is. is her boyfriend's former professor and they're the same age. And it's even more likely that they're cheating. He insists there's nothing between them.

I mean, do you believe him? Well, he's certainly trying to get this person to believe him because he now wants them both to meet. So, do we find out if this person's boyfriend really cheated with his professor or not? To hear the explosive finale, listen to the OK Storytime podcast on the IHeart Radio app, Apple Podcasts,

or wherever you get your podcast. Smokey the Bears. Then you know why Smokey tells you when he sees you past. Listen through. Remember, please be careful. It's the least that you can do. It's what you desire. Don't play with matches.

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Hello, puzzlers. Let's start with a quick puzzle. The answer is, Ken Jennings' appearance on The Puzzler with A.J. Jacobs. The question is, what is the most entertaining listening experience in podcast land? Jeopardy-truthers who say that you were given all the answers believe in... I guess they would be Kenspiracy theorists. That's right. Are there Jeopardy-truthers?

Are there people who say that it was rigged? Yeah, ever since I was first on, people are like, they gave you the answers, right? And then there's the other ones which are like, they gave you the answer. answers and you still blew it. Don't miss Jeopardy legend Ken Jennings on our special game show week of the Puzzler podcast. The Puzzler

is the best place to get your daily word puzzle fix. Listen on the Iheart radio app, Apple Podcasts or wherever you get your podcasts. All right, we're trying to send an email without leaving a ripple in the universe. And we have this arrangement of splitting photons, and one possibility of the photon goes one way,

and the other one maybe gets blocked. So how do I translate that into sending an email? Well, the first thing you'd want to do is do better than 25%. That doesn't seem like a very good bit rate to lose your information 75% of the time. So people have come up with like meta versions of this where you stack these on top of each other so that if it goes to A, you have like another chance. But wait, how am I actually communicating through these? Like, am I sending you the photon and then you're on the other side receiving the photons or what?

You only control the gate. You only control whether the right-hand path is blocked or not. So you want to send me some information? You close the gate or open it. I have like a Morse code button here that activates or deactivates the block, the obstacle. And so where are you receiving this message? So I'm controlling the laser and the detectors. and we are not in communication in any other way.

We're separated somehow, right? And so you can send me information. You can close the gate and we'll agree that, like, I'm going to send 10 of my photons through the experiment and see if I get any of them on B, and then I'll know that the gate is closed. We do not have to talk to each other or communicate in any other way, but I can tell whether or not you have closed the gate

just by seeing if any photons arrive at Dector B. Oh, I see. You're not talking about something at a distance, because we kind of have to be close to each other if I'm going to be pressing the button and blocking your stream of photons partially, right? That's right. I have to set up my experiment

so that it's possible for my photons to go through your gate if it's open. Okay, so then you're at the end measuring what comes through this arrangement. And you're saying that if you get photons in one detector, then you don't know anything. But if you get it in the other detector, then you know that I activated my gate.

Yeah, exactly. You closed your gate and shut down the quantum. quantum probabilities for one half of the beam. In that case, I know my photon didn't take your path because it went all the way through the experiment so it didn't hit your obstacle. So I know which path it took.

So I know that it didn't go through your obstacle. And yet I know something about your obstacle. I've learned something from your obstacle without sending any particles to you or getting any back from you. But I feel like some ripple has been made and you use particles to get this information, right? Like, you know, my obstacle had to come to affect and had to like act and exist, right?

And some of the time it is going to be blocking the photon, right, from going through. So it feels like a very lawyerly kind of like, hey, we got magic, but only if you sort of look at it in this very narrow and technical way. But yes, but physicists are lawyers of the universe, right? We're like, where's the loophole? The rule says we can't do exactly this. Let's see if we can accomplish it without actually doing that thing. And so, yes, it's a half step forward.

You know, we are definitely sending quantum mechanical probability. in order to communicate. I'm sending the probability of a photon your way. The fact that it doesn't make it through your gate. And so it can't come back to interfere with the other probability. It's definitely how the information is being propagated. And yet it is true that we're not sending any actual particle or any actual field. We're only sending the probability of it.

So yeah, it's a half step forward. But it's definitely not sending a message with particles or with fields themselves. Interesting. And so what is, is this an actual experiment that's been done and it works? Or is this just a theoretical construction? No, people have done this and they've actually seen these results. And so we have accomplished this. We have sent information without communicating any particles.

These photons are going through the non-obstructed path and yet telling us whether or not the other path is obstructed. And people have built up on this. You can make this more robust by stacking a few of these on top each other, having like multiple gates. You open them all at once or close them all at once. So you can make it more robust. And there's a group in China that's been using this to send information to, like, demonstrate how to actually do this. So they can, like, send information from one computer to another computer without any actual messages passing back and forth. And they've actually done this.

They sent a picture of a flower, I think it was, from one computer to another computer. How good can you get with the stacking? Like you said one photon, it's 25%. one setup, it's 25% accuracy, I guess. How good can you get it? Well, it just depends on how many times you want to stack it. So the more versions of this experiment, you have, the more opportunities you have to see that photon. And so you can get it essentially arbitrarily good if you string together, you know,

100 or 1,000 of these things. So people have some clever ideas for how to do that. But, you know, people have done this experiment. They're like communicated this picture from one computer to another without actually sending any particles. Now, there's a lot of controversy about this result. Some people feel like, there's loopholes there. They don't quite believe the result that it's really solid. So it's not like this is conclusively demonstrated.

The simple experiment with a single photon, that's definitely been done. And that agrees with the quantum mechanical predictions. The more sophisticated thing we're like are sending images from computer to computer without actually sending any particles, that's much more controversial. Right. And I think it also maybe depends on what you mean philosophically by like causing a ripple in the universe or things not interacting, right? because things are definitely interacting here.

They're just interacting in a quantum way, right? So, you know, if I'm on the opposing counsel of this courtroom universe, I might say like, hey, you're still, you know, you're still using physics. This is affecting that and that is affecting this other thing. And so, therefore, you're still causing a ripple in the universe. And it opens up really interesting philosophical questions. Like, is information physical? Is it quantum mechanical?

A lot of people think that this whole quantum mechanical stuff is just abstract, that this wave function, where, talking about. It's just like a calculation we do in our heads that helps us predict things, but the wave function itself is not real. But these kind of experiments support the other argument that the wave function itself is real and is out there and carries information on its own. Because what we're doing here is not sending information via physical objects, right, actual photons, actual electrons, but the probability of them, right, just their quantum mechanical waves. So you're right. We're still sending information using the rule.

rules of the universe and it's still propagating, but it's propagating in this probability space. And it's pretty bonkers to imagine that those are actually real in some philosophical sense. Right. Although you are still collapsing things, right? I mean, if you're sending 10, 20, 100 photons, if you're passing these through like 100 of these gates. You're essentially kind of collapsing things, right, to measure them. It collapses the wave function when you put the obstacle there, right? And that's how part of the information propagates. The fact that there is no quantum wave coming along on the right side, interfere with the left side is how you know the right side is blocked. But it's not a physical object that's being blocked. It's just the probability. It's not a classical object being

blocked. I think it's what you're saying. Yeah, it's not an observed quantity being blocked. It's just the probability. And that's the probability itself is real in some way, like has the information. And there's this deep question about information. Like, is information physical? This idea we have that it has to like propagate locally from real objects to other real objects. Maybe it doesn't. Maybe information is quantum mechanical and it can propagate through this like probability space. Which again means like maybe the wave function itself is real in some way. It's just hard to grapple with because the wave function, you know, it's a complex number. You can have values like four plus two I.

And we don't think of these as real numbers. We don't call them real numbers because they're imaginary numbers because they're just like a calculation we do in our heads. But maybe they are real, right? Because we can use them to actually propagate information that doesn't appear in physical space. All right. Well, what do you think this all means? And how soon are we going to maybe see this in my iPhone?

Well, it's a very exciting development. And you know, it serves to like break down some of these barriers to tell us that something we thought was impossible is now possible. And it might feel like a technicality to you, but it's a crack in that door, it opens it up. And maybe we can get our foot in there and then push it open and develop technologies that we thought were impossible, like sending messages between computers without actually connecting them in any way. All right. Well, it sounds like stay tuned. We might see this in the future or not,

or both at the same time. We hope you enjoyed that. Thanks for joining us. See you next time. or wherever you listen to your favorite shows. December 29th, 1975, LaGuardia Airport. The holiday rush, parents hauling luggage, kids gripping their new Christmas toys. Then, everything changed. There's been a bombing at the team. EWA terminal, just a chaotic, chaotic scene. In its wake, a new kind of enemy emerged, terrorism.

Listen to the new season of Law and Order Criminal Justice System on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. My boyfriend's professor is way too friendly, and now I'm seriously suspicious. Wait a minute, Sam. Maybe her boyfriend's just looking for extra credit. Well, Dakota, luckily, it's back to school week on the OK Storytime podcast, so we'll find out soon. This person writes, my boyfriend's been hanging out with his young professor a lot. He doesn't think it's a problem, but I don't trust her. Now he's insisting we get to know each other, but I just want her gone. Hold up. Isn't that against school policy? That seems

inappropriate. Maybe find out how it ends by listening to the OK Storytime podcast on the Iheart radio app, Apple Podcasts, or wherever you get your podcasts. Every case that is a cold case that has DNA right now in a backlog will be identified in our lifetime. On the new podcast, America's Crime Lab, every case has a story to tell, and the DNA holds the truth. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. This technology's already solving so many cases. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. This is an IHeart podcast.