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Speaker 1: Hey, Welcome to Sign Stuff production of iHeartRadio. I'm Hoorge
Speaker 1: Champ and today we're answering the question could we build
Speaker 1: a real lightsaber? A long long time ago in a
Speaker 1: galaxy that's here. Star Wars became one of the most
Speaker 1: popular movie and television franchises ever created, and arguably one
Speaker 1: of the coolest things about it are the glowing sorts
Speaker 1: of light that the characters used to fight with. I mean,
Speaker 1: what self respecting geek hasn't dreamed of holding one in
Speaker 1: their hands? But is it actually possible to build one?
Speaker 1: Do the laws of physics allow it? Or is it
Speaker 1: something that's completely in the realm of fantasy and magic.
Speaker 1: To find out, we're going to talk to several scientists
Speaker 1: who specialize in plasma and laser physics and.
Speaker 2: Who are big Star Wars.
Speaker 1: Nerdsally one of them prefers Star Trek, but I won't
Speaker 1: tell you who it is. You'll have to use the
Speaker 1: force to figure it out. So get ready to go
Speaker 1: to warp speed, because this is the podcast you are
Speaker 1: looking for. As we answer the question possible a real
Speaker 1: lightsaber is hm? I promise it's not a trap. Hey everyone, Okay,
Speaker 1: that was a lot of Star Wars puns, but don't worry.
Speaker 1: There's a lot of real cool signs in this episode.
Speaker 1: We're gonna be talking about plasmas, laser needles, and the
Speaker 1: quantum vacuum energy. All have to figure out if it's
Speaker 1: possible to make a real lightsaber and spoiler alert, the
Speaker 1: answer is actually yes. Okay. My sagat to find the
Speaker 1: answer started as most searches do on the Internet. There
Speaker 1: is a YouTube channel called Hacksmith Industries that claims to
Speaker 1: have built the first ever real lightsaber using plasma technology.
Speaker 1: So to help me figure out what plasma is and
Speaker 1: how this proto lightsaber on the Internet works, I reached
Speaker 1: out to my friends at the Princeton Plasma Physics Laboratory,
Speaker 1: a research facility in New Jersey with over five hundred
Speaker 1: scientists and engineers all working on plasma.
Speaker 2: I'm ANDREWS.
Speaker 3: Ricker.
Speaker 4: I am a PhD plasma physicist who spent my entire
Speaker 4: career at the Princeton Plasma Physics Laboratory, and I just
Speaker 4: love my job.
Speaker 5: Archro Domingas. I am a PFC plasma physicist as well.
Speaker 1: Amazing, And are you fans of Star Wars? Yes? Worse
Speaker 1: of course you're physicist. Of course.
Speaker 4: Wait was ar truly even born when Star Wars came out?
Speaker 2: Not the first one, see see, I was a teenager.
Speaker 5: I have to say I am a fan, but none
Speaker 5: of us are as much fans as my eight year
Speaker 5: old son. He is obsessed with it.
Speaker 1: Wow, you're lucky. I can't get my kids to watch
Speaker 1: any of it.
Speaker 5: Oh, I can't get him not to watch.
Speaker 1: That original trilogy or the second.
Speaker 5: So I am very proud to say that he's watched
Speaker 5: all of them, but always gravitates back to four or five.
Speaker 1: And oh, yeah, I can see why you're proud, Yes,
Speaker 1: third proud. All right, Well, I guess the question is
Speaker 1: what do you think about Lightsabers when you first saw
Speaker 1: that movie?
Speaker 4: So I saw it in the theaters, and I'm vague
Speaker 4: memories of just being blown away by these what looked
Speaker 4: like sword fights with I didn't know what they were
Speaker 4: at this time, lasers, plasmas. This was just way beyond
Speaker 4: my teenage self.
Speaker 5: So I don't think I ever remember a time I
Speaker 5: didn't know about lights So they're just kind of a
Speaker 5: thing that existed and that when I was, you know,
Speaker 5: ten or something, I found out that wasn't real. So
Speaker 5: for me, it's just been like a part of life.
Speaker 1: Okay. So there are a few concepts in physics that
Speaker 1: could potentially be used to make a real lightsaber, and
Speaker 1: one of them is plasma. Plasma is basically the fourth
Speaker 1: state of matter. There's solid, liquid, gas, and then there
Speaker 1: is plasma. If you heat up a solid, it melts
Speaker 1: and becomes a liquid. If you heat up a liquid,
Speaker 1: it evaporates and becomes a gas. And if you heat
Speaker 1: up a gas, the gas gets so hot that the
Speaker 1: electrons and all the gas atoms separate from the nucleus
Speaker 1: and you get a floating soup of electrons and positive
Speaker 1: ions the scientists called a plasma, and it can be
Speaker 1: super hot and it glows kind of like a lightsaber.
Speaker 1: So does the real lightsaber you see on YouTube actually
Speaker 1: use plasma? Well, maybe step me through it. What do
Speaker 1: you think is going on in that YouTube version of
Speaker 1: the lightsaber?
Speaker 2: So, first of.
Speaker 4: All, what they did is beautiful. I mean, what a
Speaker 4: beautiful feat of engineering and electronics. It looks beautiful, it
Speaker 4: acts beutifully.
Speaker 5: Yeah. So it's really very much like a blowtorch in
Speaker 5: which they have a directed jet of propane that has been.
Speaker 4: Lit up, and the length is related to how fast
Speaker 4: it's coming out, and as it comes out, it's cooling down,
Speaker 4: and at some point it cools down to the point
Speaker 4: where it goes out at the tip right it stops combining.
Speaker 4: That's what I think is happening. And I would argue
Speaker 4: that the hottest part is the plasma, but the edges
Speaker 4: are propably just spot gas.
Speaker 1: So the lightsaber they built on YouTube is basically just
Speaker 1: the blowtorch or not that different from a lighter or
Speaker 1: a flame. And I should mention that this video with
Speaker 1: the lightsaber has gotten over forty one million views. As
Speaker 1: they explained in the video, they found a nozzle they
Speaker 1: can blow propane and oxygen in a very steady flow,
Speaker 1: and when you ignite it, it makes very super controlled,
Speaker 1: very lightsabery flame that gets up to according to them,
Speaker 1: four thousand degrees celsius, which is hot enough to basically
Speaker 1: burn most things the flame touches. But is it plasma,
Speaker 1: that's not quite clear.
Speaker 4: That's probably a mixture of some plasma hot gas.
Speaker 1: It's a mix of it.
Speaker 5: It has some plasma in it, which leads to the
Speaker 5: light emitted because plasma has light emissions. But I also
Speaker 5: think part of it is that the black body radiation
Speaker 5: from the little pieces of stuff that burnout. So it's
Speaker 5: a mix of several sources of light.
Speaker 1: Yes, okay, this is interesting because it gets into the
Speaker 1: physics of flames or fire. A flame like from a
Speaker 1: candle or a blowtorch can't have plasma in it, but
Speaker 1: not necessarily. Here's what happens. Fire happens because of combustion,
Speaker 1: which is a chemical reaction. That reaction creates energy, which
Speaker 1: heats up what's left after the reaction, and that glows
Speaker 1: just from being hot, kind of like a traditional light
Speaker 1: bulb or a piece of metal that glows when it's hot.
Speaker 1: It's called black body radiation. So on a flame, that
Speaker 1: could be mostly what you see as the part that glows,
Speaker 1: it's just hot gas or hot bits of what's combusted.
Speaker 1: But on some flames, the center of it could be plasma.
Speaker 1: It could be so hot that the electrons get ripped
Speaker 1: from the atoms and you get a true plasma. So
Speaker 1: in the lightsaber on YouTube, it's basically a blowtorch and
Speaker 1: what you're seeing is probably a combination of a hot
Speaker 1: gas and a plasma, and it's not Medichlorian's right, unfortunately. No, Yes, Okay,
Speaker 1: So now the question is is it a real lightsaber?
Speaker 1: Does a blowtorch with a long and super hot flame
Speaker 1: count as a Star Wars lightsaber?
Speaker 5: But I think it goes back to the question like,
Speaker 5: is a lightsaber by definition? Does it have to be
Speaker 5: a plasma? I don't know what the answer to that is, right,
Speaker 5: Can a lightsaber be a very hot blowtorch?
Speaker 1: Maybe? I think it would.
Speaker 5: Still count as a lightsaber. If somebody comes up to
Speaker 5: me and does a flip and pulls that out and confronts.
Speaker 2: Me, I will run away because that, to me is
Speaker 2: a weapon made out of plasma.
Speaker 1: You'd be like, I got a bad feeling about this.
Speaker 5: Yes, exactly.
Speaker 4: I think the argument is what is a lightsaber? And
Speaker 4: since this was inspired by Star Wars, I think we
Speaker 4: have to take what was in the movie as a
Speaker 4: definition of what a lightsaber is, which means you have
Speaker 4: to be able to fight with it. As they hit.
Speaker 4: It's as if two solid pieces of metal or something
Speaker 4: are up against each other and you have to have
Speaker 4: that battle. Where now is who's that the more arm strength?
Speaker 5: I think that is Andrew's strongest argument is when and
Speaker 5: they have the fight scenes, you can stop a lightsaber
Speaker 5: with another lightsaber. I very much doubt that you can
Speaker 5: stop one of these that they made in twenty twenty
Speaker 5: with another one of these. I think they would just
Speaker 5: go through one another, And that I think is the
Speaker 5: strongest argument against it being a lightsaber.
Speaker 1: Okay, sorry, Hacksmith Industries. The physicists here from the Princeton
Speaker 1: Plasma Physics Laboratory don't think what you've made is quite
Speaker 1: a real lightsaber. If you cross to flames or to
Speaker 1: blow torches, the flames are just gonna go through each other,
Speaker 1: or the flow of the hot gases are gonna mix
Speaker 1: in the form. They're not gonna collide and feel solid
Speaker 1: like in the movies. So now the question is is
Speaker 1: that actually possible? Can you create something with plasma so
Speaker 1: that you get a glowing beam that is hot enough
Speaker 1: to melt things and cut through them and also feel
Speaker 1: solid when two of them hit each other? All right,
Speaker 1: all right, I feel like Andrew, you have a vision
Speaker 1: for making a more workable and real lightsaber from plasma.
Speaker 1: How would that work, Andrew, The.
Speaker 4: Way we do it is with magnets. All right.
Speaker 1: Here, doctor Zuicker has an idea for maybe how to
Speaker 1: make a real plasma lightsaber work, and it has to
Speaker 1: do with how scientists are trying to.
Speaker 2: Make a fusion reactor.
Speaker 1: A future reactor is basically the idea that you could
Speaker 1: create a miniature sun here on Earth. Inside of our Sun,
Speaker 1: there's incredible pressure at the very core of it, and
Speaker 1: there's plasma there, and the combination of those two things
Speaker 1: makes atoms fuse together. Well, here on Earth, scientists are
Speaker 1: working on making a plasma like that, and the way
Speaker 1: they hold that plasma together is using essentially a magnetic
Speaker 1: bottle that holds a blob of plasma together.
Speaker 4: We're trying to eventually make a miniature star like the Sun,
Speaker 4: but we use powerful magnets to keep the plasma where
Speaker 4: we want it to be and get it hotter and
Speaker 4: hotter and hotter. So if a lightsaber were to have
Speaker 4: a confining magnetic field in a tube that would keep
Speaker 4: the plasma inside that tube. Number one, you get the shape, Okay, okay,
Speaker 4: But what's interesting is that if two lightsabers, both with
Speaker 4: the same magnetic field, were to then come together. Just
Speaker 4: like your two magnets that want to repel each other,
Speaker 4: they would collide, they would not pass through each other.
Speaker 1: What doctor Zicker is proposing here is that maybe a
Speaker 1: lightsaber could be essentially a magnetic bottle. The hilt of
Speaker 1: the lightsaber could somehow form a magnetic field that contains
Speaker 1: a blob of plasma in the shape of a long tube,
Speaker 1: and it would be hot enough to glow and cut
Speaker 1: through things. And also when you hit another lightsaber, the
Speaker 1: magnetic fields would repel each other, giving you that feeling
Speaker 1: of hitting something solid. So I feel like you're saying
Speaker 1: that to make a lightsaber, you could somehow create basically
Speaker 1: a magnetic bottle in the shape of a sword.
Speaker 4: Exactly.
Speaker 2: We have so many problems with the.
Speaker 4: Why is that nonsense?
Speaker 5: What Andrew is describing is literally what we call a
Speaker 5: magnetic mirror, which is a cylinder of concentric rings that
Speaker 5: are electromagnets with a very strong one at both ends.
Speaker 5: So you've got to have some floating solid electromagnets all
Speaker 5: around the platform.
Speaker 1: To create those kinds of magnetic fields, you need to
Speaker 1: surround that whole area with magnets, which would defeat the
Speaker 1: purpose of it being like a freestanding lightsaber.
Speaker 4: I mean, my entire thing was based upon magical magnetic fields.
Speaker 1: Okay, we tried, but here's the thing about plot. A
Speaker 1: plasma is basically like a gas. It's not solid, and
Speaker 1: it wants to expand and spread out like a gas.
Speaker 1: And the only way to contain a plasma is but
Speaker 1: either something solid or you have to surround it with magnets,
Speaker 1: which would ruin the idea of a lightsaber. So it
Speaker 1: doesn't seem possible to make a real lightsaber using plasma.
Speaker 1: Does that mean a lightsaber is impossible? Well, it turns
Speaker 1: out there is another physics phenomenon that you could use
Speaker 1: to make a lightsaber, and the next two physicists that
Speaker 1: I talked to think it's totally possible. So when we
Speaker 1: come back, we're going to try to make a lightsaber
Speaker 1: out of lasers. Stay with us, we'll be right back. Hey,
Speaker 1: welcome back. We're talking about whether it's possible to the
Speaker 1: real lightsaber like the ones you see in Star Wars
Speaker 1: and so far we talked about the possibility of making
Speaker 1: one out of plasma, but as two physicists from the
Speaker 1: Princeton Plasma Physics laboratory concluded it doesn't seem possible to
Speaker 1: make one, to which I say, never tell me the odds, kid,
Speaker 1: And so we turn to another possible technology we can
Speaker 1: use to make a saver of light, and this one
Speaker 1: involves using light. In twenty nineteen, two physicists polish the
Speaker 1: paper in the European Journal of Physics titled on the
Speaker 1: physical possibility of Lightsabers, in which they say, we focus
Speaker 1: on one major problem with lightsabers that is commonly involved
Speaker 1: as an argument to dismiss them as unrealistic. Light blades
Speaker 1: are not solid and thus cannot be used in a
Speaker 1: duel as normal swords would. Using techniques coming from ultra
Speaker 1: intense laser science, we show that for high enough laser intensities,
Speaker 1: lightsaber blades can feel solid to each other. Now, when
Speaker 1: I read that, I thought, hello, there, so I reached
Speaker 1: out to doctor Jean Sebastian and doctor Francois Fillon Gardeau,
Speaker 1: the authors of the paper. Well, thank you, doctor Gagnon
Speaker 1: and doctor Philian Gardou for joining.
Speaker 2: Us like here is online.
Speaker 3: It's a pleasure to be here.
Speaker 2: Both Fasy and myself are really really huge Star Wars
Speaker 2: fans born in the seventies. I mean Star Wars shape
Speaker 2: my childhood. Really, I've watched the movie so many times,
Speaker 2: like you then by heart, and I don't know. There's
Speaker 2: something about like the Jedi Knight and the lightsaber that
Speaker 2: is just I don't know, there's something to it, right,
Speaker 2: Just the sound of it makes my hair rise on the.
Speaker 1: Amazing I guess as a physicist, when you see the movies,
Speaker 1: what do you think a lightsaber is?
Speaker 2: Actually it's funny because I think if you ask any
Speaker 2: Star Wars fan, many of them will say that it's
Speaker 2: like a plasma saber. They would say it's made of plasma.
Speaker 2: I don't know what is the origin of the idea,
Speaker 2: the exact origin, but I don't know. I'm a purist.
Speaker 2: I like the original Star Wars trilogy, and you have
Speaker 2: no mention of plasma anywhere there. We're called them lightsabers.
Speaker 1: Right, that's true. They're not called plasma sabs.
Speaker 2: They're not called planas there. They're gonna light sabers, right.
Speaker 2: Stick to that exactly for me. A concentration of light
Speaker 2: energy that's concentrated in some shape that looks like a saber.
Speaker 1: So they need to be made out of light somehow.
Speaker 2: Exactly, and that stopped at some point, it stops like
Speaker 2: the blade is finite.
Speaker 1: Oh okay, all right, Like I said, doctors Gagnon and
Speaker 1: Filian Grudeaux think they found a way to make a
Speaker 1: lightsaber actually out of light. But to do that, the
Speaker 1: design has to overcome two big challenges that people say
Speaker 1: makes it impossible to do that. Okay, Now, Star Wars
Speaker 1: is fiction, we think.
Speaker 2: All of the future. Actually it happened a long time
Speaker 2: ago in the galaxy far far away. It already happened.
Speaker 1: That's right, that's true. Good point, that's right. Well, we
Speaker 1: can only hope. But people say that lightsabers are impossible.
Speaker 1: What do you think people say lightsabers are impossible to
Speaker 1: be made out of light?
Speaker 2: Yeah.
Speaker 3: One of the reasons for one thing is out do
Speaker 3: you stop light after like a meter of propagation? You know,
Speaker 3: when you have a leaser. Think about the leaser pointer
Speaker 3: for example. The laser pointer will go on forever until
Speaker 3: it hits something or it's reflected on something, so light
Speaker 3: naturally does not stop by itself. One thing that it's
Speaker 3: just for a lightsaber that would be hard to do
Speaker 3: or hard to implement physically.
Speaker 1: Okay, So the first challenge in making a lightsaber out
Speaker 1: of light is that light, when it's admitted, tends to
Speaker 1: want to keep going on forever. So how do you
Speaker 1: make a sword out of light that has a finite length?
Speaker 1: And the second problem, it's the same problem we had
Speaker 1: with the plasma lightsaber, which is how do you make
Speaker 1: the lightsaber feel solid?
Speaker 2: You've seen the movies when the two blades clash together,
Speaker 2: they actually feel solid. But of course that's not what
Speaker 2: you would expect from light, right.
Speaker 1: Right, Like if I cross the flashlights.
Speaker 2: You can just do it and you see that they're
Speaker 2: just like whoa go through each other.
Speaker 1: And that's because light doesn't necessarily interact with itself exactly,
Speaker 1: That's exactly it.
Speaker 2: So if you think that light is made of photons,
Speaker 2: let's say, so little particles of light, they are electrically neutral,
Speaker 2: so it means that they don't have any electromagnetic interaction
Speaker 2: between them. They don't interact in any other way in
Speaker 2: terms of like other forces, like nuclear forces for instance.
Speaker 1: So to a photon, another photon is just invisible.
Speaker 2: Yes, in some sense classically clastically, of.
Speaker 1: Course, they have no way that we traditionally understand that
Speaker 1: they can interact with each other exactly. So those are
Speaker 1: the two reasons people say making a lightsaber out of
Speaker 1: light is impossible. One how do you make it finite
Speaker 1: so the light beam doesn't go on forever? And two
Speaker 1: how do you make light feel solid? Well, it turns
Speaker 1: out there is a way to get around both of
Speaker 1: those problems, and no, it does not involve using the force.
Speaker 1: We'll start with making a finite beam of light.
Speaker 2: According to doctors.
Speaker 1: Canon and Fillian Cordeaux, you can do it with something
Speaker 1: called a needle of light. I've definitely done that as
Speaker 1: a kid, Like when you have a flashlight and you
Speaker 1: turn off the lights and you pretend that you're swinging
Speaker 1: a lightsaber around, but you're right that it keeps going
Speaker 1: on forever. Is that something that you think you have
Speaker 1: a solution.
Speaker 3: For, Well, not the direct solution, but if you look
Speaker 3: at the scientific literature and the research done by any physicists,
Speaker 3: it's called a needle of lights and so it's a
Speaker 3: very particular electro magnetic fail configuration.
Speaker 2: They are very hard.
Speaker 3: To do in a laboratory, so you need very special
Speaker 3: mirrors to do them, but they have the property that
Speaker 3: when this light is focused, the energy will be in
Speaker 3: the form of a long cylinder.
Speaker 1: WHOA, I don't think I was expecting this. Is there
Speaker 1: a process in physics that might allow that to concentrate
Speaker 1: light in a short beam like that?
Speaker 3: Yes?
Speaker 1: Yes, yeah, yes, yes, okay. Can you describe this phenomenon?
Speaker 1: What is it?
Speaker 2: How does it work? I imagine like you're sending a
Speaker 2: light beam that would be cylindrical, so it would be
Speaker 2: more like an annular type of beam. It means that
Speaker 2: instead of having like a cylinder that is filled with light,
Speaker 2: you would only have like the outskirt of it, like
Speaker 2: a ring.
Speaker 1: Oh I see, Instead of a solid beam of light,
Speaker 1: you're shooting out a ring of light.
Speaker 3: Yes, exactly.
Speaker 2: Then you send it on. Imagine in the hilt of
Speaker 2: the lightsaber there will be a mirror at the back,
Speaker 2: and then you send towards that mirror, and then when
Speaker 2: it's reflected like at the focus of the mirror, it
Speaker 2: would look like a needle. And it's what I said.
Speaker 2: It's related to the fact that you have like many
Speaker 2: beams of light. When it reflects to the focus, some
Speaker 2: of those beams will kind of interfere with each other.
Speaker 2: It will cancel in many places, but it would add
Speaker 2: up at the focus.
Speaker 1: And so that gives you a little light needle.
Speaker 3: Yep, exactly.
Speaker 1: Okay, the details of this are a little hard to explain,
Speaker 1: but it is something that physicists that specialize in optics
Speaker 1: and lasers have been able to do. By shooting light
Speaker 1: as a ring instead of a solid beam, and bousing
Speaker 1: and off special curved mirrors, you can essentially focus the
Speaker 1: light beam so that it interferes with itself and concentrates
Speaker 1: its energy into a kind of needle or sharp stick
Speaker 1: of light, and that basically looks like a light saver,
Speaker 1: Like the black waves are interfering and they're building up
Speaker 1: in this needle in this length of space.
Speaker 2: Yes, yes, so the energy of the beam would be
Speaker 2: concentrated in that tiny needle.
Speaker 1: And not anywhere else.
Speaker 3: So there would be much more energy conceptor along the
Speaker 3: needle than the rest.
Speaker 1: But the light would keep going after the needle, it
Speaker 1: just wouldn't be focused.
Speaker 3: Yeah, exactly, so it would be diffuse. After the needles
Speaker 3: you want, it will still propagate, but the energy will
Speaker 3: go down drastically, so it would look like a small
Speaker 3: light saber.
Speaker 1: Uh huh. We would see like an actual seat of
Speaker 1: glowing beam like a lightsaber.
Speaker 2: Well, yeap.
Speaker 3: Actually, it depends a little bit on the medium. So
Speaker 3: let's say you would open the slight sliaber in air.
Speaker 3: She could create a plasma and the plasma could start
Speaker 3: to emit light.
Speaker 1: I see. The light will then cause the air molecules
Speaker 1: to glow.
Speaker 3: Basically, yes, yeah, exactly.
Speaker 1: Okay, yeah, we did end up with plasma. But here
Speaker 1: the plasma is only the reason we see the lightsaber.
Speaker 1: The actual sword is technically made of light. So does
Speaker 1: that solve the lightsaber problem?
Speaker 2: Kind of? There is one little problem.
Speaker 3: And I think you can have a slender that's about
Speaker 3: fifty thousand times the wavelength of your user. And so
Speaker 3: that's say in the optical regime, and for example, blue
Speaker 3: fits around five hundred danometers, so time sixty thousand, that
Speaker 3: will be the length of this needle of light.
Speaker 2: So we're talking about probably a millimeter. Yeah, it has limitations, right,
Speaker 2: So it seems that they are able to do it
Speaker 2: for about the size of one millimeter.
Speaker 1: What the physicists are saying is that this needle of
Speaker 1: light phenomenon depends on the wavelength of the light you're using,
Speaker 1: and so far, the longest needle scientists have been able
Speaker 1: to make is about one millimeter long. In other words,
Speaker 1: we can make a life lightsaber out of light, but
Speaker 1: at least so far, it would only be one millimeter long. Now,
Speaker 1: is it possible to make it longer?
Speaker 2: The answer is maybe.
Speaker 1: Star Wars would be a lot less exciting if it
Speaker 1: was called the light needle. Could I make it longer
Speaker 1: by using a longer wavelength of light?
Speaker 2: I think so?
Speaker 1: Oh oh, now we're getting somewhere like.
Speaker 2: An infrared faber.
Speaker 1: Oh yeah, I think it could work infrared. If so,
Speaker 1: it would be red.
Speaker 2: I don't know.
Speaker 1: The first lightsaber would be a sift lightsaber. It's harder
Speaker 1: to make a good guy lightsaber, as I think that's
Speaker 1: kind of one of the lessons of Star Wars is
Speaker 1: that fear and anger are easier. Exactly, that's the bath
Speaker 1: of the dark. The Bath of the Dark set is
Speaker 1: easier yep, more plausible, more physically practical. Yeah, okay, so
Speaker 1: that's where we stand on the problem of making a
Speaker 1: finite beam of pure light. It's possible to make a
Speaker 1: needle of light, but so far they are really short.
Speaker 1: It might be possible to make them longer using longer
Speaker 1: wavelength light, which would make the lightsabers red, but nobody's
Speaker 1: tried it do it. It sounds like maybe we need
Speaker 1: some physicists to make it work. Okay, when we come back,
Speaker 1: we'll tackle the other big problem in making a lightsaber,
Speaker 1: which is how do you make a beam of light
Speaker 1: feel solid? As it turns out, there is a way,
Speaker 1: and it involves tapping into the quantum vacuum energy of
Speaker 1: the universe. We'll get into that, so don't go anywhere.
Speaker 1: We'll be right back.
Speaker 2: Hey, welcome back.
Speaker 1: We're talking about whether we can build a real lightsaber
Speaker 1: when that has a beam of light that stops at
Speaker 1: a certain length, that can cut through things, and crucially
Speaker 1: that you can spar with. In the movies when the
Speaker 1: Jedi and the Cyth cross swords, they hit each other
Speaker 1: and they feel solid. But as we learn, making a
Speaker 1: lightsaber out of a plasma blowtorch meets all the requirements
Speaker 1: except the last one, and so it turned to lasers.
Speaker 1: According to doctor Johan Sevest and doctor Francois fon Grdeaux,
Speaker 1: to laser physicists, it's possible to make a beam of
Speaker 1: concentrated light, although you'd have to work on making it bigger.
Speaker 1: But amazingly, they do think there is a way to
Speaker 1: make a beam of light feel solid.
Speaker 2: So that was more the main focus of our paper.
Speaker 2: So the idea is this. So we just said that
Speaker 2: if you have two photons, they cannot interact directly with
Speaker 2: each other, but it doesn't mean that they cannot interact indirectly. Okay,
Speaker 2: this is a huge feel of research. It's called nonlinear optics. Oh,
Speaker 2: so imagine that. Now you would have let's say a
Speaker 2: medium in which you can shoot light through it. So
Speaker 2: you send some light into it, and now let's say
Speaker 2: the first photon that goes in will probably interact with
Speaker 2: the medium itself, think of it as deforming it a
Speaker 2: little bit. And then imagine the second photon that comes
Speaker 2: after that. Now, that second photon will feel the deformation
Speaker 2: of the first one. So in that sense, even if
Speaker 2: the two photons do not interact directly, they could interact
Speaker 2: indirectly through the medium.
Speaker 1: Okay, here's the scenario that the physicists are imagining. Normally,
Speaker 1: photons of light just ignore each other. Light is electrically
Speaker 1: neutral and it has no mass, So photons can't push
Speaker 1: or pull or bump into each other. If you take
Speaker 1: two flashlights and you across the beams. The beams of
Speaker 1: light just keep going straight. I mean, who hasn't done
Speaker 1: that as a kid. But there is a way for
Speaker 1: photons to interact indirectly with each other. Photon can interact
Speaker 1: with the medium it's traveling in. Think of it as
Speaker 1: leaving a ripple or a trail in the medium, and
Speaker 1: then the next photon that comes through, say from a
Speaker 1: different lightsab would feel that ripple or trail. And that's
Speaker 1: how two lightsabers might possibly feel solid to each other.
Speaker 1: I see. There are effects just from the light going
Speaker 1: through the medium that you have to take into account
Speaker 1: that sometimes.
Speaker 2: Yeah, okay, it happens mostly when the intensity is very large.
Speaker 3: Yeah.
Speaker 1: Oh, it has to be powerful enough to feel that
Speaker 1: effect exactly. So it has to be.
Speaker 3: Powerful enough to deform the medium. So we send the
Speaker 3: language to polarize it so it pulls the electron in
Speaker 3: one direction, let's say, more than the other, so that
Speaker 3: it changes and if another sluton comes in, it's propaggation
Speaker 3: will be modified.
Speaker 1: So you could imagine this working in air as the
Speaker 1: medium the lightsabers are in. But doctor Gannon and doctor
Speaker 1: Phillian Grdeaux are envisioning something more universal. A lightsaber that
Speaker 1: could work anywhere, even space.
Speaker 2: The next step is, but we don't want to rely
Speaker 2: on the medium for that thing to work. We wanted
Speaker 2: to work in vacuum, like in the movie in space.
Speaker 2: Look like in the movie, if you want to turn
Speaker 2: on your lightsaber on your spaceship and use it, you can't.
Speaker 1: Well, technically, I think every time you see a lightsaber
Speaker 1: in Star Wars, they're in air.
Speaker 2: That's true.
Speaker 3: True.
Speaker 2: We don't want it to depend on which atmosphere of
Speaker 2: the planet in your room.
Speaker 1: Yeah, okay, okay, got it, got it, all right, So
Speaker 1: let's try to make a lightsaber that works in a vacuum.
Speaker 1: Go ahead.
Speaker 2: So the question is if it is vacuum, then you
Speaker 2: might say, like, it's completely empty, right, so there are
Speaker 2: no media, right, so there cannot be any indirect interact
Speaker 2: between the photons. What but it can, that's the thing.
Speaker 2: So if you're talking about the quantum vacuum, quantum vacuum
Speaker 2: is full of stuff.
Speaker 3: Yeah.
Speaker 2: Yes.
Speaker 1: As it turns out, empty space is not really empty.
Speaker 1: It has something that physicists called the quantum vacuum energy.
Speaker 1: The theory is that empty space actually has something like
Speaker 1: a background buzz or a low level of energy that
Speaker 1: predisposes it to create particles out of nothing.
Speaker 2: So it's full of what we call virtual particles.
Speaker 1: I see, empty space is not really empty. It has
Speaker 1: kind of like a bubbling frost of quantum particles that
Speaker 1: come into existence and disappear.
Speaker 2: Right according to the theory, Yeah, according to what like
Speaker 2: the best theories that we have right now to describe
Speaker 2: the microscopic world. They come into existence, but they go
Speaker 2: back to the vacuum in such a short time that
Speaker 2: we can't even measure them. That's why they are called
Speaker 2: virtual particles. I see.
Speaker 1: But light as it goes through a vacuum, does interact
Speaker 1: with virtual quantum particles.
Speaker 2: Yes, it does, exactly.
Speaker 3: And actually one effect that it's supposed to happen when
Speaker 3: you reach a very very high intensity is that you
Speaker 3: can actually create matter directly from light. So light would
Speaker 3: interact with this particle and it would pull them, and
Speaker 3: then you can start generate electron pulls it from pairs
Speaker 3: directly from light.
Speaker 1: I see. Okay, Okay, So let's say I have a
Speaker 1: laser super intense, I shoot it. It's interacting with the
Speaker 1: quantum vacuum, and is the idea then that it's that
Speaker 1: trail that it leaves. That interaction would then affect the
Speaker 1: other lightsaber. Is that where we're going, Yeah, exactly.
Speaker 2: Yeah, So imagine you would have like two lightsabers at
Speaker 2: ninety degrees with each other, and then they clash like
Speaker 2: in a fight for instance, and then there is an
Speaker 2: interaction region between the two lightsabers. And then so imagine
Speaker 2: some of those photons come from one of the hilts,
Speaker 2: and then because of this indirect interaction between the photons
Speaker 2: through the vacuum, then some of them might reflect towards
Speaker 2: the other light saber. And as I said, if the
Speaker 2: intensity is high enough, then a lot of those photons
Speaker 2: will get reflected towards the other hilt. And if you
Speaker 2: have enough photon on the other hilt, then you will
Speaker 2: feel that as radiation pressure.
Speaker 1: Oh, you would feel a force.
Speaker 2: You would feel a force in the hilt.
Speaker 1: Yes, So that's kind of the idea. If you have
Speaker 1: two of these laser swords, when they hit each other,
Speaker 1: they would interact with the quantum vacuum energy, which would
Speaker 1: cause photons to be reflected from one sort to the other,
Speaker 1: and then those photons would make you feel a force
Speaker 1: through what's called radiation pressure. Basically, when photons hit something,
Speaker 1: they actually give whatever they're hitting some momentum, pushing it back.
Speaker 1: It's what may solar sales work. And that push Doctor
Speaker 1: Gannon and doctor Phelan Grideaux argue would make the light
Speaker 1: beams feel solid. I see, I see like we're fighting.
Speaker 1: We're having a lightsaber battle, and we swing our lightsabers,
Speaker 1: and when my beam crosses yours, I'm going to feel
Speaker 1: a little kickback maybe on my lightsaber. Yes, yeah, because
Speaker 1: of these quantum effects.
Speaker 5: Yep.
Speaker 3: Actually in the film called that quantum reflection. So it's
Speaker 3: really a quantum effect that induces these direction between photons
Speaker 3: and that reflect them.
Speaker 2: Back towards the hill.
Speaker 3: Then that's what we think would make it feel. I
Speaker 3: don't know if it will feel solid, but you will
Speaker 3: feel something.
Speaker 2: We kind of analyze how you would feel it, and
Speaker 2: it will feel very different than just like hitting something solid,
Speaker 2: that's for sure.
Speaker 1: I see. It won't feel like you're clashing swords, but
Speaker 1: you'll definitely feel something that kicks you back.
Speaker 2: Oh yeah, something like that.
Speaker 1: Yeah, all right, well I think we did it that.
Speaker 1: It's possible to make a real lightsaber sort of. You
Speaker 1: can't have a standing beam of light and yes, it's small,
Speaker 1: but as Yoda said, size matters not you can also
Speaker 1: cut through things, and you could technically make it feel
Speaker 1: solid or at least like it hit something. Does that
Speaker 1: mean we should all grow a ponytail and become pata ones.
Speaker 2: No, well, hey, let's say let's put it in fury.
Speaker 2: But one of the things that has been pointed out
Speaker 2: is that, well, you need an energy source, right, and
Speaker 2: the energy source, of course, has to fit into the
Speaker 2: hilt of the lifesaver.
Speaker 3: Leather batteries all work for this.
Speaker 6: Yeah, it could not work so to have a significant
Speaker 6: effect to feel let's say a kickback on the other hilt,
Speaker 6: for instance, and it's ten to the twenty three watts.
Speaker 2: So that's just a shy less than the output of
Speaker 2: the thought.
Speaker 1: You take the entire sun's output. That's how much you
Speaker 1: need to feel a little kickback at this light saber
Speaker 1: through this effect, meaning your lightsaber would be as powerful
Speaker 1: as the sun. Yeah.
Speaker 4: Almost.
Speaker 2: These effects are weak.
Speaker 1: Yeah, the effects are weak, so you need a lot
Speaker 1: just to get it.
Speaker 3: So you need to put in a lot of soot
Speaker 3: on to see something or to feel something because.
Speaker 2: The problem is so small.
Speaker 1: Okay, yeah, this kickback the fact that might make the
Speaker 1: lightsaber feel solid depends on a quantum physics interaction that
Speaker 1: is very unlikely, and so you need a lot of
Speaker 1: photons to make it happen, which means your lightsaber needs
Speaker 1: to output the same amount of energy as the sun.
Speaker 1: But hey, as jin Urso said, rebellions are built on hope.
Speaker 1: Maybe there is a way to get that kind of energy. Okay,
Speaker 1: all right, Well I'm not the terror because I know
Speaker 1: kyber crystals are who knows how they work?
Speaker 3: Right?
Speaker 1: Maybe they have the power of a sun.
Speaker 2: Oh yeah, people say that that's what also power the
Speaker 2: Death Star. So that's another of my calculation that I do.
Speaker 2: If one of my electromagnetic courses, I mean, it takes
Speaker 2: a lot of energy for that later beam, trust me.
Speaker 1: Well, let's take it a step further. Guys, is a
Speaker 1: Kyberg crystal possible?
Speaker 2: Well, I would like to know what is the Kyberg crystal?
Speaker 1: Yeah.
Speaker 3: In the article, we talk about electron positron bears recombination,
Speaker 3: which is probably one of the most efficient nichanism to
Speaker 3: generate energy.
Speaker 2: So, as Fransos said, so the most efficient way would
Speaker 2: be to use antimatter when you annihilate let's say to
Speaker 2: an electron and a positron, all of it becomes energy.
Speaker 1: I see, a positron is like an anti electron basically, right, Yeah, yes, exactly, So.
Speaker 2: If you annihilate them, then you get like as much
Speaker 2: energy as you can coming from that mass. So that's
Speaker 2: probably the most efficient way. So I don't know if
Speaker 2: kyber crystals are similar, for there be rate on a
Speaker 2: different level than that, but as far as we know,
Speaker 2: the best would be antimatter and aliation.
Speaker 1: This could be the subject of a whole other episode,
Speaker 1: but antimatter is regular matter that has its quantum number flipped.
Speaker 1: So if you take an electron and you flip its charge,
Speaker 1: you get a positron, which is an anti electron. And
Speaker 1: if you mix a matter particle with its antimatter version,
Speaker 1: they annihilate and give out a whole bunch of energy. Now,
Speaker 1: could you power a lightsaber with that, Yes, but you'd
Speaker 1: need a lot of it.
Speaker 2: So even that, you would still need like one hundred
Speaker 2: million kilograms of that into your hilt.
Speaker 1: One hundred kilograms of matter and antimatter one hundred million
Speaker 1: kilogram Yeah, being annihilated at a time.
Speaker 2: The time to power it for about a minute.
Speaker 1: That's a lot, lot. That's a lot, a lot.
Speaker 2: It would squeeze all of that into the hilt. Would
Speaker 2: be so similiar to like a white dwarf and the
Speaker 2: neutron star.
Speaker 3: Uh.
Speaker 1: Even if you take that much matter and antimatter squeeze
Speaker 1: it down to a hilt, you'd be basically carrying a
Speaker 1: sun with you.
Speaker 2: Yeah, you can carry it. Interesting, I mean I think
Speaker 2: you would need the pores to actually life.
Speaker 1: Oh, there you go. That's how it works.
Speaker 3: Why they need the far Yeah, the power their lightsabers.
Speaker 1: Yeah, this is not looking so good. But the real
Speaker 1: kicker is that shooting light actually.
Speaker 2: Creates a kickback. Like if you turn on a.
Speaker 1: Flashlight, the flashlight actually gets pushed back, kind of like
Speaker 1: give you fire a gun.
Speaker 2: The effect is super small.
Speaker 1: Because light has very little momentum, so you don't actually
Speaker 1: feel it with a flashlight, but at the intensities of
Speaker 1: light we're talking about in our lightsaber, it would be
Speaker 1: a lot.
Speaker 3: When you turn your lightsaber on, you'll have some kind
Speaker 3: of recoiled effects like a trust and the estimated that
Speaker 3: the trust.
Speaker 2: There's like ten to the seven saturn five rockets, like
Speaker 2: put like strap them all on together and when you
Speaker 2: just power it on. That's what you would.
Speaker 1: Feel ten to the seven Saturn five rockets. Wait, if
Speaker 1: I have a laser four, that's how much when I
Speaker 1: turn it on, that light would actually push me back?
Speaker 3: Yes, exactly.
Speaker 1: Wait Wait guys, I feel like you're saying that the
Speaker 1: thing that disqualifies Star Wars as fiction is not lightsabers.
Speaker 1: It's not Kyper crystals. It's Newton's second law of motion.
Speaker 3: Yeah, you're probably right.
Speaker 1: Everything else is possible, but Neaton's second law says no,
Speaker 1: that's all fiction.
Speaker 2: Yes, that's a very nice way to summarize it.
Speaker 1: You're right, all right, Well, to summarize our space opera
Speaker 1: to a galaxy for are far away. It's definitely possible
Speaker 1: to build a real lightsaber that glows in a beam
Speaker 1: and can cut through metal. I mean, the folks on
Speaker 1: YouTube did that, but it doesn't feel solid. To make
Speaker 1: a lightsaber that feels solid, you could make it out
Speaker 1: of lasers and have it interact with the quantum vacuum energy.
Speaker 1: So it's possible, but it would require you to have
Speaker 1: the power of the sun in the palm of your hand,
Speaker 1: and it would probably kill you just from the recoil
Speaker 1: of turning it on. But here's the thing about lightsabers.
Speaker 1: Even if they can't be real or practical, the effective
Speaker 1: hat on physics is definitely real. Here's how our physicists
Speaker 1: put it. What do you think is so fascinating about lightsabers?
Speaker 2: I don't know.
Speaker 3: It's so like it looks like an efficient weapon, a
Speaker 3: noble weapon of a more civilized.
Speaker 1: Age, the idea of combining a sword, which as a kid,
Speaker 1: swords are cool, but now it's a sword made out
Speaker 1: of like lasers. Yeah. Yeah, that did Star Wars influence
Speaker 1: either of you a little bit and your choice to
Speaker 1: become physicists.
Speaker 2: Maybe at some deep level. I mean I always been
Speaker 2: interested with sci fi in general. So Star Wars, of course,
Speaker 2: as I said, shape my childhood.
Speaker 1: It makes people wonder what's possible?
Speaker 3: Yes, yeah, exactly, and personally for me, just the fact
Speaker 3: that you know they were in space, and so I
Speaker 3: think this movie brought interests to astrol physics, a rockets,
Speaker 3: things like that. So it's not direct Star Wars, but
Speaker 3: it's via space that brought me to physics.
Speaker 1: Thanks for joining us, See you next time, and hey,
Speaker 1: may the Force be with you. Music and Time Effects
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