Getting Entangled with Sean Hodgman

25:25So red goes one way, blue goes the other way, or blue goes one way, red goes the other way. You could entangle a red and a blue

25:32Neil deGrasse Tyson:particle. Yeah. Yep. I did not know that. I thought they had to be kind of sort of symmetrically identical, you know, with just complementary elements like spin or whatever. So that's interesting to me. Okay. So in practice, how are you entangling particles? That's the first question, right, Chuck? Yeah. Yep. Yep. Yep. So in practice, that's, that's, um, we, we take one, one particle and we give it a kick and we collide it with the other particle and they bounce off each other. And then you get in this superposition of, um, the particles going, as we're talking about Northeast, Southwest, or Northwest, Southeast.

26:10And, um, uh, so you're in these, these different momentum states and that's your, um, initial entangled state.

26:16Neil deGrasse Tyson:So the act of colliding them off each other brings their wave functions into harmony. So what was two wave functions becomes one. Yeah. Yeah. I think that's a really good way to describe it. There's two separate wave functions that you can describe separately. And then after you collide them, there's no way that you can describe them with two different wave functions. You have to use a single wave function. Wow. Gotcha. And this is because the wave particle duality of nature at those smaller scales. This is quantum physics at its finest, right? Yep. Okay. So the second question was what, Chuck?

26:57How do we know they are actually entangled with spooky action and not just similarly related? That seems to be the real question there. Yeah. Yeah. So I think that that kind of goes back to, again, if they were classical particles, you could put them in this, you could put them in kind of a superposition where they either go one way or the other way. But quantum mechanically, they go one way and the other way at the same time. And so the reason we can, and the way we can prove that, even though we only ever measure one outcome, is that if we then take the two halves of that superposition and we combine them back together and interfere them, then we can show that there'll be different outcomes.

27:41And so the particle can essentially interfere with itself and we can show we'll get different outcomes to what you would get classically. Wow, man. That's all right. That is some freaky stuff. I love it. It's Freaky Friday. Yeah. So this is Hayden Gorringe, I think. Gorringe. He says, hey, Dr. Tyson, Dr. Hosman, Lord Nice, Hope you are all doing well. It's in the paper by Dr. Hodgman et al. That the helium atoms were momentum entangled. And I hadn't heard of subtypes of entanglement before. What other types of entanglement are there? And why did the team opt to use momentum entanglement for the BEC made of helium atoms?

28:34all the best Hayden from London, England. Pip, pip.

28:38Neil deGrasse Tyson:What is the inventory of entanglements that you have? Yeah, so there's lots of different types of entanglements. So if you have the original experiments with photons, it would often be something such as polarization. So polarization is just, if you imagine a photon as a small particle of light, it's basically which way is the light vibrating? Is it vibrating this way or is it vibrating this way? So vertical or horizontal. and you might entangle your photons in that so that one of your photons has vertical polarization, one has horizontal. And so you could be in a superposition of vertical going right, horizontal going left, or horizontal going left, vertical going right.

29:13And then you could measure that. And yeah, and so that was a lot of the original experiments were done with photons with things such as polarization. Atoms, previous experiments have done things such as spin. So spin is just a, it's a fundamental property of atoms or charged particles that you can either sort of spin up or spin down. And you could be in a superposition of spin up and spin down and entangled with that. And in our case, we did momentum. Pretty much any quantum property can be entangled. You just have to be able to put it into a superposition of those states.

29:52Neil deGrasse Tyson:Well, let's get back to the spin. So in the two entangled spin particles, does one have to be spin up and the other has to be spin down? No, no, definitely not. As physicists, we tend to use a shorthand that if there's any system that is a two spin system, you'll call that spin up and spin down because that's how we tend to learn about it in undergraduate physics. And we tend to just. Yeah, yeah. Yeah. So for instance, in my lab, we've done previous experiments where we've used a spin one and a spin zero state of helium and we've entangled them. And but we still call it spin up and spin down because it's just it's shorthand that physicists understand easily.

30:34Neil deGrasse Tyson:Because when I think of quantum particles, I think they have complementary quantum states. But that's not the case. They can have any quantum state. You just have to be able to couple between those quantum states. If you can't couple between the quantum states, then you can't interfere them. So if you can't change the state, coupling just means changing. So I can't change controllably from spin one to spin zero or spin up to spin down or horizontal to vertical polarization. Whatever your entanglement parameters are now experiment, it's momentum. And so as long as you can change coherently between those states, you can get entanglement and show a Bell inequality violation.

31:16Okay. Wow. Look at that. That is mind bending stuff.

31:21Neil deGrasse Tyson:I did not know that. I did not know that. Okay. Bring on some more. He says, hello, Dr. Tyson, Dr. Hosman. This is Jonas Williams from New York City. My question for you, has the study of quantum entanglement and subatomic particles changed or influenced how you understand reality? I like that. I like that. If you're not purposely entangling particles, is that something that can happen to them by natural causes? Oh, definitely. Yeah, yeah. Entanglement can happen all the time. It's just that it's because it happens on such a small scale, we normally don't see the effects of it. And so, yeah. Yeah, and I think that, so back to the question, for me, it's kind of, it's really weird.

32:14And I think a lot of us who have studied quantum mechanics, when you first encounter it, whether it's in an undergrad or high school or through a podcast like this, when you first hear about these quantum features, you might think, yeah, that sounds really weird. That can't be how the world works. And then because it's not how our brains have evolved. Our brains have kind of evolved to be used to sort of throwing things at animals, I guess, which is a very classical way of looking at the world. and if I throw a cricket ball or what do you have baseball in America if I throw a baseball let's say um and uh it's not going to be in two places at once it's not going to go two directions at the same time and so when we read about quantum mechanically that a small particle which we like to think of as just a smaller smaller ball um when we read that can go both directions at once uh we just sort of think oh well it must be some mathematical trick and the fact that we can actually do these experiments that show no no at the very small scale or very cold um this is how the universe works it's yeah it's a bit mind-bending right yeah without a doubt to

33:21Neil deGrasse Tyson:summarize because it happens on these microscopic scales there's no macroscopic manifestation of entanglement that we experience yeah that's because we're just trying to not get eaten by the lion, and that doesn't require quantum physics to accomplish. Are they forever separated, the quantum and the macro physical, or is there a possibility that there is a point of crossover? Yeah, that's a really good question. And that's a really active area of research at the moment. Because clearly at the small scale, quantum works. At the large scale, quantum doesn't. but there's got to be somewhere in between.

34:03There's either must be a hard point where they stop working or maybe it's a fuzzy boundary. A lot of the research we're kind of seeing these days is that there might be a fuzzy boundary where you just kind of get less and less quantum and more and more classical. Wow. All right. God, how do you deal with this every day, man?

34:25Neil deGrasse Tyson:All right, here we go. Do you arrive at home at the end of the day depressed? or jubilant? It normally depends on how much university bureaucracy I've had to deal with in a particular day. Quantum physics is the easy part of the job some days. As they say, the administration is a new kind of subatomic particle called the moron.

34:50Damn. Okay, this is Mike Parker. And Mike Parker says, Dr. Hodgman, Dr. Tyson, Lord Nice. Mike Parker from Virginia. It seems entanglement is observed in larger and larger particles. Is there an upper size limit to entanglement? Could there ever be a way to use particle entanglement for instant long distance communication or other practical purposes? This is the question that every sci-fi fan wants to know, man. Can we have faster-than-light communication like on Star Trek where, Captain, there's a subspace communication waiting for you in your quarters?

35:33Neil deGrasse Tyson:Or can you entangle molecules? I mean, yeah, we're impressed with the atoms, but what have you done with us lately? Can you entangle molecules, be they simple or complex? On the entangling larger particles, that's another really active area of research. People keep pushing it further and further. There have been people that have entangled collections of atoms and molecules, and they sort of push. I believe it's of order 1 ,000 atoms, but don't quote me on that because I could be wrong on that. It's more than one is all I care about. It's way more than one. Yep. Yep. And so, yeah, trying to push this entanglement on the bigger scale and work out where it breaks down.

36:11At some level, it clearly doesn't work anymore. And so, yeah, where that transition is a really active area of research.

36:20Neil deGrasse Tyson:So maybe you were familiar with George Gamo's Mr. Tompkins in Wonderland. I don't know if you – I'm a little older than you, so I don't know if this was around in your day. but george gamau uh mr wonderland was a place where the laws of physics were different simply by the physical constants being different so one of them the speed of light is like 60 miles per hour right and so you're driving down the street and then you see these these relativistic effects just by approaching the speed of light as your speed limit on the road one of them was they change the value of the Planck's constant so that macroscopic objects would feel a quantum phenomenon that you'd walk through the door and you'd like diffract.

37:07Neil deGrasse Tyson:It's just, it's fun to think about what, how that, if you have a knob that could tune it, what different things would happen to you? Or we just simply develop a new sense of, of what the world is, right? Like you said, we throw the ball and it follows one arc but if quantum rules were all around us at all times and you threw the ball and it split into two states you would say oh it's just splitting into two states it wouldn't even be odd to watch that because it would happen so frequently is that a fair way to think about this yeah i think so our brains are great at adapting and i'm pretty sure that if we'd had to evolve to live in a quantum world i'm sure we'd just think it was normal.

37:51Neil deGrasse Tyson:It's just normal. That's right. That's cool. And what about the communication portion of Mike's question? Oh, yeah, yeah, yeah. Would it ever be a viable use for long distance communication? Is there a future in this? Yeah. So this is what everyone thinks as soon as you hear entanglement. You think there's instant, measuring one instantly changes the other. We could use that to communicate faster than the speed of light. Unfortunately, that doesn't seem to be the case. And essentially it's because the way you measure it contains information. So if you make a measurement on that particle, yes, you will know what the other one is, but you won't be able to communicate that in a useful way unless you communicate it classically because the other person would then have to make a particular measurement to get anything useful out of that.

38:42And so, yeah, you can't actually use it for faster than light communication. There's a theorem called the no communication theorem, which basically says that, yeah, you can't use entangled states to communicate faster than the speed of light.

38:58Neil deGrasse Tyson:Really? That's the name of the theorem? The no communication theorem? That's the best name they can come up with? I believe that's what many women call their husbands. The no communication theorem. But yeah, so basically what you're saying is the collapse of the superposition, once that information is set, you can't know it unless you're making the same measurement that the other person is making on the other side. And you wouldn't be able to know which position it is unless you were to call them and say, here's the position. Yeah, exactly. Because quantum measurement perturbs the state, if you make your measurement in a way that could exploit that information, it will change the state of it.

39:49And so then that will change the state of it. And then when they make their measurement, they'll get a different result out of it. They'll get a different result. Unless you've called ahead and told them, hey, you need to make this particular measurement. Which, by the way, is how you know that it's entangled. That's how you know it's entangled. Exactly. It's kind of frustrating. You're like, we should be able to do this, but yeah, we can't. So we can't use it for encrypted message sending? Now, that's a completely different question. You can use entanglement for encrypted message sending. So that's where you exploit the fact that if you measure one half of that, you will change the other half.

40:30And so if you encrypt your message on two photon pairs and you send one of them to the person that you want to and you keep the other one yourself, then if you make measurements on that and compare the results with the person you've sent it to, you'll know if anyone's messed with your system because you'll get different results. And so you'll know if it has been eavesdropping on your messaging. And so there's mathematically provably secure encryption protocols using quantum communication, which can be shown that you just can't break them because if you interfered with it, if you did interfere with the state, if you listen to it, you interfere with the state, and people would know you're eavesdropping, and you could just abort the communication.

41:13Neil deGrasse Tyson:So this is a pipe dream then. It's a pipe dream that people have for it. These things have been demonstrated at various scales. And yeah, they're essentially, it's almost an engineering problem at this stage to get it to work better. Okay, look at that. All right, this is William Warren. And William says, hi, Dr. Tyson and Dr. Heisman. This is William Warren from Abingdon, Maryland. If quantum entanglement is a fundamental feature of nature, could space time itself emerge from a vast network of entangled particles? In other words, is it possible that distance isn't fundamental, but rather a consequence of how information is connected at the quantum level?

42:07Thank you so much.

42:08Neil deGrasse Tyson:We've heard on another installment of StarTalk from one of our physicist friends, Brian Green, that it might be that the virtual particles in the vacuum of space that are connected to each other by entanglement, they're entangled, that that entangled gap between them may be a wormhole. and a wormhole would have the same property because you just step through and it's you're just there right you're not moving faster than light the the hole enabled that and it's not because you had special rockets so so what what is the latest thinking other than what i just shared with you about what the entangled pathway actually is yeah wow this is um you gotta remember I'm only a dumb experimentalist.

43:08I basically make measurements in the world.

43:11Neil deGrasse Tyson:You dumbass experimentalist. Okay. I probably, I would certainly defer, yeah, thinking on that to things such, to the experts like Brian and co, because, yeah, that's kind of a bit beyond what we're working on. It certainly sounds like an interesting take, but I'm, yeah, I'm not really sure, unfortunately sorry okay no okay but listen we we like that answer uh you know nowadays it's hard to get somebody to say hey i'm not that sure sorry you know what i mean yeah it's a really good point i think it's a big part of being a scientist is you've got to learn to know what don't you know and it's one of those things that the more you know the less you know you know it's kind of the reverse dunning-kruger effect you know the dunning-kruger effect but the less you know the The more you think you know, it's kind of the reverse.

44:05The more you know, the more you realize that, wow, there's heaps of stuff that I just don't know at all. And yeah. Dunning-Kruger, we get along very well. Very well. Dunning and Kruger, I know them. We have a great relationship. They told me I do the best Dunning and the best Kruger.

44:25All right. I think there's a value in saying I don't know and allowing people to understand that science is sometimes the answer is, well, we don't know. Absolutely.

44:38Neil deGrasse Tyson:It's different from him not knowing. They're two different. There's science doesn't know and there's this I don't know. Those are two different things. Right, and they're both the same from me.

44:51Whether physics itself knows, I think the answer is still out on that as well. I think there's still some open theories in that because, again, you can come up with a theory, but you have to be able to prove it experimentally. And I think to prove something like that experimentally, it would be extremely hard. So there's some really interesting theories and the trick is going to be a bit like with Einstein's spooky action in a distance claim, coming up with an experiment to test it. That's what will be, yeah, that would be a big Nobel Prize discovery. Cool.

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49:29all right let's go to alejandro guardado and he says

49:38Neil deGrasse Tyson:He's from Hackensack, New Jersey. No. Where's he from? Where's he from? I don't think Alejandro says where he's from. Oh, okay. He says. He's from Monterey. No, and Washington State. I'm sorry. He did say Washington State. Washington State speaks that way. I just want you to know. Okay. That's my fantasy of Alejandro in Washington State. He says, hey, Dr. Tyson, Dr. Hodgman, Lord Nice Alejandro here from Washington State. My question is, what stabilizes quantum fluctuations when particles fuse or collide? How does this increasing proximity affect entanglement more extremely? How would this work for particles in the singularity of a black hole?

50:34Thank you.

50:35Neil deGrasse Tyson:Ooh. Yeah, so I want to reshape that just a little bit. So if I have two particles, we know that quantum physics says everything is always in motion, there's always some energy to the state. Does that disrupt any attempt to entangle two particles? So in other words, can two particles natively break apart simply because of quantum fluctuations that are inherent in all particles in all systems? Quantum fluctuations at some level will probably have an effect on entanglement, but it's normally at such a small scale that it won't stop entanglement happening, I think. And in fact, when you cool down your helium atoms, you are reducing the quantum fluctuations by dropping the temperature, correct?

51:26We're kind of reducing the classical fluctuation. So temperature is really a classical phenomenon. phenomenon, it's just random motion of particles, we're reducing the classical fluctuations to get to the scale where you can, in principle, see quantum fluctuations. However, for our entanglement, for our particular system, the quantum fluctuations don't really come into it. There's much larger things that cause the entanglement to decohere, things such as classical, so magnetic, stray magnetic fields and the like.

52:00Neil deGrasse Tyson:Your macroscopic disruptions to it. Yeah, definitely. We're not really at a level where we're sensitive to the microscopic quantum fluctuations. This is Mikael Beusvert, who says, hello, guardians of the geeks. Mikael here from Canada. I like that, guardians of the geeks, right? How would the universe change if the programmer behind would suddenly toggle particle entanglement off?

52:31would we notice a change in our everyday life wow by the way in the same spirit of that i heard

52:40Neil deGrasse Tyson:someone suggest that evidence we're in in a simulation is that the programmer already put a limit to how fast things can go because they can't simulate it faster than that so the speed of light is the programmer's limit that we've bumped up against. And it took a long time to get there, but we finally got there. So it's like in the Truman Show, he finally gets to the outer edge. Of the set, of the telemetry set. Of the set, of the set. So, yeah, so what happened? Turn off quantum entanglement, what's different about the world? yeah so at the macroscopic level i think um probably probably not not a huge amount like entanglement's only the very small scale um however well yeah however there are a range of processes that we're starting to have hints at that may be really entanglement may be really important there's some biological processes such as um people are postulating the stability of dna may be due to entanglement within the molecules itself.

53:48Navigation of birds. Some birds use magnetic sensors, and there's hints that there's quantum elements of that that rely on entanglement. Migration. Migration of birds. Migration of birds, yeah. Navigation during migration is kind of what I mean. Like when they migrate, how do they know to go north? Yeah. How do they know which way to go? Yeah, gotcha. And so there's thoughts of that. And even things such as I think photosynthesis is the latest one that they're looking at that may have elements. Now, I think the jury is still out on all of these. Again, it's not quite my area of expertise, but I believe the jury is still out on all of these as to whether it's definitely quantum entanglement enhanced.

54:27But there's definitely some evidence that's starting to point towards some of these biological processes. Quantum physics is really important and entanglement in particular. And so, yeah, while at first glance you might think that if the programmer of the universe turned off entanglement, we wouldn't see anything, any difference. It may actually be really important. Okay. Very cool. I love the idea of photosynthesis and quantum entanglement. That sounds so cool. All right. This is Bruce Lessie. And Bruce says, Dr. Tysons and Hodgman. This is Bruce Lessie from Cripple Creek, Virginia. My question is related to entanglement and spooky action at a distant as Einstein phrase.

55:08it if space time for a photo traveling at the speed he said photo but i think he means photon uh traveling at the speed of light represents zero time experienced by the photon because at the speed of a light distance is non-existent why did einstein have a problem with instantaneous communications between entangled particles nothing is at a distance for particles that travel at the speed of light. Yeah, so I'd say that's one of the reasons why it's really important to measure entanglement for things not just that aren't photons. So yeah, because photons travel at the speed of light, if you just measure entanglement with that, you could perhaps come up with some sort of explanation like that.

55:53But in our system, we measure it with atoms. Our atoms move very slowly. We give them a kick and they move at several centimeters per second. Let's call it an inch per second for you Americans with your freedom units.

56:07Freedom units. Oh my God. Freedom units. That's exactly what we use to measure the octagon on the White House law. Freedom units.

56:25So, yeah, so back to the atoms. So because they're moving relatively slowly, you can't come up with that sort of an explanation to explain it. It really, and simultaneous, yeah, instantaneous communication suddenly becomes a problem again. Wow, that's really cool, man, because, yeah, they have mass, and, yeah, they're entangled at much, much, much slower speeds. So, yeah, that's really, well, it's still a good question. Oh, it's a great question. Great question. Yeah, really good question, Bruce. Thanks. All right. This is David Barlow. And David Barlow says, greetings, Dr. Hosman, Dr. Tyson Lord Nice.

57:04David Barlow from Chicago, Illinois here, a newly signed up Patreon supporter. Kudos to you, my friend. he says I was wondering if as an experimental physicist and an observer within the quantum field you and your associates knew for a certain for certain that you were not affecting the results of your experiments in the Bell's theorem what loophole prevention precautions were taken to negate your field collapse of the wave function when taking measurements love your fantastic science broadcast guy. So, yeah, how do you know that you're not messing it up? Like...

57:52It could will be. You always have a big doubt that, yeah, did we just do something wrong and measure something? That's why we have to do sort of rigorous and multiple tests. And for the scientific method in general, it's part of the reason why you have to publish these papers that other scientists can then go, hang on, did you think about this did you try turning this off did you try turning that on and yeah um it's it's yeah it's an important part of the process um for our particular experiment so maybe i should just briefly cover what loopholes are that are referred to there so with with bell with bell experiments um there's these things called loopholes which are basically ways that people come up to say well maybe to still preserve locality to still preserve the fact that um you don't have instantaneous communication.

58:37And so it can be things such as, well, maybe the experiment's conspiring in a way such that it only lets certain results through, or maybe the observer is communicating in a way. Maybe if you set the interference on the two halves of the system and the measurement, if you don't set them after you've – if you set them in a way that they could communicate with each other, maybe there would be some really weird theory that could explain that. And so a lot of these, all these loopholes have been closed with the experiments on photons. For our particular experiment, we didn't close all these loopholes.

59:18So our experiment isn't loophole free. In principle, you could make some of these criticisms about our experiment. However, the fact that they've been closed with photons means that we probably expect that they should also be closed for atoms as well. and so yeah and part of the reason why we didn't close them was because a couple of them are technically extremely challenging to close with atoms just because atoms move a lot slower than photons and they move over much smaller distances and so yeah it's an ongoing area of work it would be a good area of future work for groups like us that's a damn good question chuck we have time for a couple more cleo fox he says hello dr tyson my name is cleo from denver colorado modern quantum physics has achieved extraordinary predictive accuracy, but many of its foundational interpretations remain experimentally indistinguishable.

1:00:09Given recent advances in quantum information theory, weak measurements, quantum computing, and tests of non-locality, do you think the next major breakthrough in quantum physics is more likely to come from developing new mathematical frameworks or from entirely new experimental methodologies capable of probing quantum phenomena in ways we cannot currently access. Put another way, are we currently limited by our theories or by the tools we use to test them?

1:00:42Neil deGrasse Tyson:Yeah, so I was going to say something similar to that in summary of that question. So, Now, Sean, there's, you know, philosophers like believing they have access to emerging truths in science in general, but especially in quantum physics, where there's so much that makes no freaking sense. So is there room for philosophers to guide the physicists through this and or out of it? Or are we just stuck just, as they say, shut up and calculate? And so that's a nuanced way of saying, what was the final question there? Are we currently limited by our theories and the tools we use to test them? On the shut up and calculate versus philosophy debate, I'm a big believer as an experimenter.

1:01:34I'm a big fan of shut up and calculate. Experiments are hard enough as is. Count me on that vote as well. Okay. Yeah. It's basically the math tells us the results that give us predictions of our experiments. and it works yeah and it works and and and so at that level yeah i'm happy with that i'm happy to leave the questions to the essentially to the realm of philosophy to an extent if if you if you're um if you can't actually make predictions of what an experiment will give you i think that's basically philosophy and um i think there's definitely a role for that i mean we've we've seen that how brain bending some of these quantum effects are and i think it's really interesting to probe that.

1:02:12I think it's really interesting to have philosophers and the like guide that and theorists and interact with quantum theorists. But I think it's also equally really important for experimentalists to actually test these results. And if you can't test these results, then you probably need to work harder on your theory, I think.

1:02:32Neil deGrasse Tyson:I spent some time at Princeton where they're very theory-based, although they do quite a bit of experiments there and they have a tokamak and fusion reactor. But there's a strong theoretical legacy in the department and there's a sign up somewhere or someone's door. It says, never trust an observation unless it's backed up by a good theory. Yeah. Yeah. So I think coming back to the question, it really is, it's both. There's a lot of work on theory, but there's also a lot of work on experiments to cover that. Do they inform one another, I think is kind of also the spirit of the question. Ideally, there you go.

1:03:17Neil deGrasse Tyson:That's the correct way to think about that, Chuck. Absolutely. There's plenty of times, like our experiment on entanglement, that was originally proposed by some theorists. We tried to do it the way they proposed and it didn't work. So then we came up with a slightly different way and then we came back to them and then they helped analyze our results and it yeah it's really there's a lot of back and forth that okay cool cool cool chuck one more question we got time for it all right let's close it out with melanie stickler and melanie says hello dr tyson i'm melanie originally from austria now in the bay area of california my question is about dr hosman's helium experiment i understand massless photons have wave-particle duality, but how does a massive particle like a helium atom, which is subject to gravity, function as a wave cloud?

1:04:06Furthermore, if measuring a quantum system collapses the wave function, how do the team measure the atoms in simultaneous momentum states without instantly destroying the superposition? I'm sure the paper covers this, but I'm having a hard time wrapping my head around it, So thank you.

1:04:27Neil deGrasse Tyson:Yeah, helium is a massive particle compared to stuff we're used to. And so there's a wave function associated with such a massive particle? Yeah, definitely. And I should say, great question. And yeah, there's a wave function associated with helium atoms. And that's why we need to cool them down to make it work. Because otherwise, at room temperature, the wave function is so small that you can't see it. But at these temperatures, the wave function is macroscopic. It's sort of in the order of tens to hundreds of micrometers. So that's a 0.1 of a millimeter. And yeah, it's quite large at that scale.

1:05:05The other part of the question, if I remember, if I'm getting it correctly, was how do you measure that they're in two different states at once when they're only ever going to be in? How do you prove they're in two different states at once when you can only ever measure one result? And again, that really comes down to John Bell's work for how you can measure this Bell inequality, where if you interfere those states, you can measure the results of that in the outcomes you get. You can interfere those states and you can get more probability of being in one than the other in your output due to the fact that you were in this superposition of two states at the same time.

1:05:36Neil deGrasse Tyson:Is there a quantum entanglement arms race in the world? Like who's leading the quantum entanglement experiments? Because I don't think it's us. Is it us Americans? You're in Australia. yeah, who's ahead and who's behind? It kind of depends what you're talking about. I mean, our experiments proving the fundamentals of entanglement, there's still work going on in that. But a lot of what current quantum research is going into is how we do something useful with entanglement. So how you can use it. So things such as quantum computing. So quantum computing is a computer that rather than using bits to encode information, so bits have to be one or zero, you use qubits, which can be in a superposition of one and zero at the same time.

1:06:22And then if you have multiples of these together, you can end up with, you can entangle the different qubits. And by the fact that you can have qubits in many states at once, for certain types of problems, you can probe many answers at once, even though you only ever get one result when you get out, when you do your final measurement. And so there's a large, so in principle it seems really promising that you should be able to do much faster calculations, much higher level computation with this. But the problem is that finding, there's only particular problems that we know of that this is true.

1:06:58So, there's a lot of work going into that. Then the other problem is that quantum systems are really hard to get to work on a large scale, so have lots of qubits. And so, there's a lot of work going into building these processes. And so, yeah, there really is, if you want to call it an arms race, there's a lot of government and private investment in this at the moment. There's a lot of quantum computing startups all around the world. And the assumption that whoever gets

1:07:23Neil deGrasse Tyson:advances in it first might have a leg up, either economically or with regard to security or computing. And so even if at the end of the day, it's just a pipe dream, because it's like, It's just a fun physics exercise, but it doesn't have any practical use. No one knows that yet. Is that a correct way to think about that? Absolutely. It's still really an open question as to what the impact of quantum computing will be. Quantum computing could be anything from, like you say, have massive economic implications, massive security implications. It could be used to things such as medical implications like drug development, data processing.

1:08:08all these massive things, or it could just be on a much smaller level and that it's kind of a toy physics system that helps us advance physics, but may not have quite such a wide economic implication. And I think it's a really, really exciting time.

1:08:23Neil deGrasse Tyson:I bet people said the same thing about quantum physics a century ago. This is just a curiosity on the fringes of physics. We'll never have any use for this, but it's still fun anyway. and now it's the foundation of our IT revolution. Everything. Everything, yeah. It's one of the reasons it's really important to invest in basic research. I mean, the work my group does is... We don't know what that is anymore. In the United States, we don't know what that is anymore. Exactly. We don't do research here anymore. Will you hire, hire, hire? Australia's not much better, unfortunately. We run on vibes.

1:09:01Neil deGrasse Tyson:Vibes. No, right now it's on physics fumes. That's all that's left. Oh, yeah. Unfortunately. We'll find out. Yeah. Well, Sean, that's all the time we have. I'm saddened by this because this topic has no end of curious people out there thinking about it. They've read about it. And it's not every day you get to bump into someone who gets paid for thinking about it. Congratulations on your Bose-Einstein condescent as a source of entanglement. Okay, we will look for our invitation to Stockholm in the mail. Really good. And thanks a lot for the questions. And yeah, thanks for having me on your show.

1:09:41Neil deGrasse Tyson:I am Neil deGrasse Tyson, your personal astrophysicist, finishing up a very special edition of Cosmic Queries, specializing in quantum entanglement. Until next time, keep looking up.

1:10:25The BZ Woodland

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