What is the Real Physics behind a Lightsaber and When Can I Get One?
In terms of modern Science fiction that has really captured the imagination, the Star Wars lightsaber has really become a pop culture icon. There are Lightsaber apps, phone sounds, fan movies, all kinds of toys and serious geeks everywhere build their own that can cost up to thousands of bucks. But will this amazing device that seems to be such a straight forward idea ever be able to actually exist? We have seen several sci-fi concepts become real in the last 30 years. You're probably looking at this on a flat screen right now, which first only existed in science fiction. You might even be listening to a music player which first made its debut on Star Trek. The problem with the lightsaber concept isn't that it can't be made, its just that most everyone gets it wrong using the physics of the universe.
In the original concept of George Lucas, it was called the laser sword. This was the original term used by him when he and Spielburg were working on the original concepts. In fact, in order to get the technical and visual effects done the way that Lucas wanted on this particular device, many hours were spent at his own, newly created visual effects company to make it look the way he envisioned.
In terms of the physics behind how one might work, there has been all kinds of conjecture. Most of it is simply impractical in terms of science, much of it simply won't work. There are a few ideas today that can mimic it, but no one seems to have hit on that magic combination.
Now, you might be thinking, "So its Sci-Fi, its in the future, so we just haven't invented it yet." Well, given enough time and money, eventually anything's possible...right? Well, its probably a really good thing that we can't really make one of these things yet because...
I am pretty sure I'd be in that big green area. Yah...
So lets put forward some of the ideas that have had some merit or actual thought put into them and see where this goes using real physics as our guide.
To start, there are some ideas or "canon" behind how a lightsaber is supposed to work. Of course, its just complete fiction in terms of science, but if your going to really, really make one do you have to follow the blueprints of what somebody else just made up?
In this case, I would say you have to be a true to the central ideas of the lightsaber design in order to call it a lightsaber. Here is an internal design that I dug up from the web that basically lays out the whole internal structure to at least one type of light saber design. There are other designs out there.
There are some basic ideas of what the internal parts have to be in order to call it a lightsaber. There are two crystals (a focus and primary crystal), a portable/rechargeable power source, some lenses for setting the blade length and width (on some designs), a on/off switch, a magnetic emitter ring, power adjustment controls, field energizers and basically the rest of the thing is a handle.
When you look at it in terms of sword construction, there are some glaring problems with the design. Why would you put your on/off switch right in the middle where you can accidentally turn it off in the middle of a battle by mistake? Why would you have power control switches in the open for someone to mess with when your not around? What happens if this thing is hanging on your belt and someone bumps into you and it turns on by mistake?? Alas, maybe that's why a Jedi has to go through so much training.
The Major Ideas of Construction found to date:
Idea #1: Lasers
When the lightsaber first hit the scene back in 1978, there were few who saw that it would become the focus of so much interest. Even Han Solo thought it was just a gimmick. People often thought that it has to be some kind of laser in order to work. I even remember reading crazy reports that one of the tech crew build one for real to save the money in post production because George ordered him to do it!
While it may seem like a viable idea to use lasers, there are a couple of glaring problems with the actual physics behind this approach.
While we know that lasers can be capable of cutting through metal and just about anything given enough power, we quickly get to three main issues.
The first one is the laser beam itself. In a lightsaber, the blade is about 39 inches. Now, as we were shown above, blade lengths can be variable, and in the movies they did vary quite a bit. But a laser beam has no way of just stopping in the air. It would continue on for miles. Even my hand held green laser can shine a very long way.
BTW -Don't shine your lasers around at night, Pilots really don't appreciate the light show as much as you do.
Maybe you're thinking that you could create a mirror that reflects it back in some way? What would keep the mirror in place and how would you be able to thrust the blade into a solid object with that little mirror on the end? Nope! Another obvious thing is that a laser is not really visible unless its coming into contact with something - a wall, a screen, dust in the air, so it doesn't visually work.
The next problem is the clashing or hitting of the blades together. While you could be thinking that its pretty neat that the lasers bounce off of each other, in reality, even at ultra-high power strength, light has no mass. It would be no different then trying to have a lightsaber battle with two flashlights. They would simply just pass through.
The third big problem is power. We simply have no way to keep that much juice flowing into a lightsaber unless we develop some very new technology. Now many propose that they have mini-super conductor batteries in the star wars universe, and lets just say they do. But to power a laser with that much cutting power for the amount of time in the movies, well, your talking about harnessing kilowatts of power for minutes at a time, and this causes issues with the way that matter can be transformed into energy without simply going nuclear in your hand.
Luckily someone already did the work of figuring out the amount of energy we are talking about to cut through objects as seen in the movies. There have been several articles published on this and it can actually be deduced based on some of the scenes, like where Master Qui-Gon melts the door with his lightsaber. Some materials had to be guessed at, but since there seems to be plenty of room for the lightsaber to perform admirably and we're just trying to guess at it, we can proceed with these variables.
Here is a link to the article: Scienceblogs
From the article we need a power source to deliver 28 kWatts in a sustained manner when called upon. We can look at battery technology today and know that we cannot even get close to that in energy density unless we hook up directly to a power plant. We know that the Jedi do recharge their lightsabers from the stories, so its not an infinite source of power. Good, because that's simply impossible with physics. (Ever hear of the perpetual motion machine?) From the article above, we know we have no way to do this without causing a huge explosion and a huge amount of heat. We simply have no way to direct, in a controlled way, that kind of energy in that small of a space with the matter in this universe taking into account all kinds of materials and efficiencies of the power conversion itself. Even if the power cells were 99% efficient at converting energy to the blade, your still looking at ~300 watts of power that has to be dissipated out of the device every second when its in full use. I don't advise holding onto anything thats emitting 300 watts in any form. Its bad.
Conclusion: Lasers are clearly a big NO!
Idea #2: titaniuim-Tungsten Torch
After thousands of dollars of research into a proto-saber, Hacksmith has developed a mock saber that does actually function, but not exactly like a true lightsaber. While this is about the closest thing I've seen using today's technology, its really a mix between an oven coil and a big TIG welder. The design idea is unique and freaking awesome being that these guys are really experimenting in a shed in their backyard. This youtube video takes you along for the ride to see how they did it.
While almost all of the requirements to make this a lightsaber are missing, (no crystal tech, blade is fixed and it has a huge battery pack on the outside) it is the best concept that today's tech can offer to a few guys building it themselves.
Conclusion: A for effort, nice try...but too many things missing. Just the fact that they did this is damn cool!
Idea #3: High Strength Ceramic pop-up blade
In an interesting Science Channel episode, Dr. Michio Kaku discusses his idea of a lightsaber being a plasma torch. His design utilized technology that is available today except for the batteries, which he thought could be available in the next 50 years. His blueprints utilized a titanium fan to suck in the surrounding air which becomes the plasma fuel and the ceramic lattice somehow (he never explains) pops out of the handle to be the blade that the plasma flows around. It is much better and more feasible in terms of the energy requirements as well. While this idea does have merit and does look and act like a lightsaber in many ways, it seems to fall short. Have you ever slammed two porcelain dishes together? Not exactly the sword fight I am thinking of. He admits he needs to create a new family of ceramics in order to do this. It would truly be magical stuff to have a ceramic that can withstand up to 12,000 degrees and be ductile and fracture resistant. We should call it Mythril. Carbon nano-tubes might be a better solution in some ways.
To me this idea is more of a plasma cutting tool than an actual lightsaber. No crystal technology that is central to the lightsaber theme is at play with this explanation. He never stops to think about how ceramic lattices could be dueled with and the different colors of a lightsaber blade are also ignored.
Conclusion: B+ for effort, nice try...but NO! Hater's gotta hate.
Idea #4: High-Density Magnetically Contained Plasma Loop
This has been the most discussed theme behind lightsaber technology for some time. The ideas behind this do allow for stable plasma fields to be contained within the magnetic bubble and plasma is ionized matter. If subjected to a return loop, the plasma could circulate creating a longer sustained plasma field (much more energy efficient) and the plasma ion elements could create the different colored blades that are seen. Neon for Red, Chlorine for Green, Argon for Blue and Xenon Purple.
But this too has its issues. Creating a magnetic containment bubble in that sharp blade like appearance is hugely inefficient to do without other outside hardware. Even in the wildest dreams of physicist, additional technology would have to be put in place. If its handled as a simple tube of magnetic energy, then all the plasma leaks out the far end and it losses its energy so quickly that the whole effect falls apart.
RF and sound frequency plasma containment is a strong possibility by using finely tuned sound waves to create additional nodes of plasma containment, and this could, in theory, also account for some of the sound effects as the surrounding atmosphere is bounced away. Well, that's kind of cool.
But alas, have you ever taken two strong magnets and tried to set them next to each other? If the North/South poles are aligned the same, they repel each other, just like a lightsaber should behave, but if the poles are opposite, they slam together and stick. Not much of a battle. Hey, let go my lightsaber! Of course this is the physical magnets, and not the magnetic fields, they pass right through each other.
And forget about the efficiency of electro-magents and the amount of energy you'd have to push through them to create the kind of field you would need. In order to be able to effortlessly melt through things like steel and aliens, the plasma blade would need to have an enormous amount of energy- about 20 megawatts to melt steel – enough to power 14,000 households before the battery ran out. Super conductors might be able to solve the energy needs, but matter heat dissipation still gets in the way with those darn laws of physics again.
And there is no crystal at its core. The central theme of a lightsaber is those special crystals.
Idea #5: Finely tuned flame thrower
I just saw this recently and wanted to include it because its crazy enough and its cool visually.
The fuel wouldn't last very long. It doesn't have near the energy required to mimic a lightsaber in cutting strength and again, no crystal at its core. No actual blade to fight with because flames would just pass through each other.
I think this could be defeated by an asbestos jacket, not that I want one.
When he holds it up to his face, you get that viceral reaction, "Oh man don't do that", but then imagine how bad it would really be with one wrong twitch....
Conclusion: Cool....but not even close.
Idea #6: Antimatter Stream
This was an idea that came to my mind when watching an episode on the power of antimatter explosions and the cancellation of matter. I suppose that antimatter would be an extremely effective way to cut through just about anything except neutron star material. You could mimic the cutting power of a Light Saber very easily. The question is would you be able to control the reaction. Would you want a 100 nuclear bombs worth of explosive power in your hands that you toss about with reckless abandon? I really don't want to take out a whole city or entire region because my lightsaber's magnetic containment malfunctioned. Another issue would be the intense radiation from the matter being destroyed. Gamma radiation and all kinds of heat and light would be generated, most likely killing you in a few milliseconds.
Conclusion: Effective and COMPLETELY CRAZY!
Idea #7: Solid Light Technology
This is a relative newcomer to science and physics. Arranging photons (light) into molecules, scientists have discovered a completely new form of matter that works just like the lightsabers in Star Wars. "The physics of what's happening is similar to what we see in the movies," said one of the researchers at MIT.
Now don't expect to run to Radio Shack...did I just date myself? Or Sharper image...whatever, and pick up your new lightsaber soon, but at least we have a newly discovered state of energy that behaves like a lightsaber.
Credit for the experiment goes to Harvard physics professor Mikhail Lukin and MIT physics professor Vladan Vuletic, who blasted photons through a cloud of rubidium atoms. When they sent more than one photon at once, they noticed that the particles clung to each other to form a molecule.
"It's not an in-apt analogy to compare this to lightsabers," said Lukin (Skywalker?) in a press release. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."
Now to be fair, they stumbled across this effect because they were experimenting on building quantum computers. But the whole concept is mind blowing and could lead to technology that mimic not only lightsabers, but the whole holo-deck ideas in Star Trek as well. (Sorry to mix the genres together as I know that the hard core fans pretty much don't do lunch together.) But discovering a new state of matter is a pretty big deal.
So how does this work, you might be asking yourself.
The researchers constructed what they call an “artificial atom” made of 100 billion atoms engineered to act like a single unit. They then brought this close to a superconducting wire carrying photons. In one of the almost incomprehensible behaviors unique to the quantum world, the atom and the photons became entangled so that properties passed between the “atom” and the photons in the wire. The photons started to behave like atoms, correlating with each other to produce a single oscillating system. As some of the photons leaked into the surrounding environment, the oscillations slowed and at a critical point started producing quantum divergent behavior. In other words, the correlated photons could be in two states at once.
“Here we set up a situation where light effectively behaves like a particle in the sense that two photons can interact very strongly,” said co-author Dr. Darius Sadri. “In one mode of operation, light sloshes back and forth like a liquid; in the other, it freezes.” The system created so far is very simple, with the light entangled with the atom at two points. However, it should be possible to increase this, greatly expanding the complexity and range of possibilities of what is being constructed.
Houck and his team hope the frozen light could be made to behave like materials that do not exist, but have been hypothesized by physicists, allowing them to explore how these things would react if they were real.
Why this New Physics Works as a model for a Lightsaber
This explains not only a mechanism behind the creation of a lightsaber, but why you need a light conducting crystal at its heart to manifest it. The crystal become the heart of the blade and the template for which the solidified light builds its quantum entanglement upon. The hue of the crystal alters the spectrum on which the blade is built from, creating a blade color emission that matches the crystal color characteristics. It also explains the meditation that the Jedi chant as they complete their Lighsaber.
The crystal is the heart of the blade.
The heart is the crystal of the Jedi.
The Jedi is the crystal of the Force.
The Force is the blade of the Heart.
All are intertwined.
The crystal, the blade, the Jedi....
We are one.
Conclusion: Awesomeness!!! Perhaps, if this continues to be funded, scaled up models can be created, and it could lead to a lightsaber that functions like one, but it would still need to have room temperature superconductor power cells and some much better understanding to this new state of matter. Being that is it powered by light, the energy requirements should be less than creating megawatt lasers and more along the lines of industrial mercury-arc lights (kilowatts). It could lead to many amazing inventions.
I give it about 50 to 150 years out.
Sources: MIT Physics, Harvard Physics, Princeton University, Gizmoto & IFL Science, Hacksmith.ca