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It is the time of year we all have been waiting for. Ho, ho ho! The Star Wars are around the corner!

Help me design scientifically plausible light-saber:

In other words: What has to happen in order to have light-sabers available?

  • After watching the latest Star Wars, all scientists decide to produce lightsaber (why? Because its cool!)
  • We have all Earth people cooperating on this task (one big hand wave)
  • Goal is to produce something resembling Star Wars light saber, including its powers and wearability
  • Target delivery: In next 30 years
  • Some hand waving is allowed. However, we need to stay inside plausible sector.
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    $\begingroup$ I think I have the explanations for your light-saber except for the battery and how it can be used to deflect energy based projectiles, btw nice hat you've got! $\endgroup$ – user6760 Dec 14 '15 at 8:08
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    $\begingroup$ I think there was a tv show that depicted this... Michio Kaku Can you build a real Lightsaber $\endgroup$ – Scott Downey Dec 14 '15 at 9:05
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    $\begingroup$ Related: youtube.com/watch?v=1lr5OUjFDkg $\endgroup$ – Aify Dec 14 '15 at 9:42
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    $\begingroup$ Your biggest problem will be getting the beam to stop a fixed distance from the source. Most light/ energy beams (laser pointer, flashlight) go until they hit something. Otherwise, you really just need to take an existing thing (laser cnc) and figure out how to miniaturize it. $\endgroup$ – cobaltduck Dec 14 '15 at 13:24
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    $\begingroup$ @MichaelKjörling It should probably also be tagged as ancient-history. $\endgroup$ – Samuel Dec 14 '15 at 21:28
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The missing components are metamaterials and ultra-high power sources.

The meta material required is one which provides:

  • Excellent shear strength
  • Superconductivity
  • Extreme temperature resistance

The power source needs to be able to provide 28 kilowatts for however long the blade is in operation.

Combining those two elements, one can create a lightsaber. A telescoping rod, like a collapsible police baton, made of insulated coils of this metamaterial will act as the base of the sword. The power source will provide a high current that when passed out through the blade returns toward the hilt through magnetically confined plasma.

enter image description here

For the image above, the current flows in through the base, out the top and back through the plasma contained in the magnetic field. The coil is required so that the return current does not cause magnetic fields which cancel the containment field. The initial turning on of the blade is going to be a little less smooth than a traditional lightsaber, but once you learn not to wince, the electrical arcs that precede the plasma are going to look pretty awesome.

It's not clear if your saber would be red (it'll depend on the atmosphere and metal dopants), but I'm guessing yours will be.

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  • $\begingroup$ Would the metamaterial go up through the blade, as The Anathema suggested, or stay contained in the base/hilt? $\endgroup$ – AndyD273 Dec 14 '15 at 20:52
  • $\begingroup$ @AndyD273 I'm not sure what Anathema was conceiving, but I think it was just a rod that could hold a cap in place. The metamaterial blade will be surrounded with plasma in this case. $\endgroup$ – Samuel Dec 14 '15 at 20:54
  • $\begingroup$ His first suggestion was the rod holding the cap, but after pointing out that it wasn't needed he thought it might at least be useful for parrying since it gives something to strike against. As you point out, it would help with the field too, so there's that. $\endgroup$ – AndyD273 Dec 14 '15 at 21:01
  • $\begingroup$ @AndyD273 Ah, well, it serves as the field generator and the parry body here. $\endgroup$ – Samuel Dec 14 '15 at 21:13
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    $\begingroup$ @Wingman4l7 Well, it still retracts... $\endgroup$ – Samuel Dec 15 '15 at 21:34
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Plasma can be influenced and contained by magnetic fields, and can be generated by using a laser. If you had a powerful focused laser in the hilt you could create some really high temperature plasma that would be vented out and contained by the magnetic field into a blade shape. You might not even need much of a magnetic field, since it would work a bit like a blow torch.
A plasma blade has a few advantages over laser, in that it doesn't need a reflector at the end, and would deflect or absorb plasma bolts.

Plasma can get up to 1,000,000 degrees, though you'd want to use lower temperature plasma since that would ignite the air around you.
It could definitely cut/vaporize most things it touches.

Here's a real world micro version of the technology in action using "cold" plasma in a pretty purple blade shape: http://www.livescience.com/6052-plasma-jets-replace-dental-drills.html
enter image description here

Edit:
This meets the requirements for needing a gem to create and focus the laser, and AFAIK light sabers are never referred to as laser swords, or how they work. People just assume lasers because of the gem and how they look, forgetting that you wouldn't see a laser beam in the air, and you wouldn't be able to stop it at only a few feet long. Turn it on and you're cutting holes in the ceiling 100 feet above you. At that point you're better off turning it into a blaster with unlimited energy and unbelievable power.
A plasma cloud would be visible, and shorter range, and could be used for piercing.

Power is still a problem (may need some handwaving), and would require some next gen power source, but if you could assume a major breakthrough in batteries or an accidental discovery on how to tap into ZPE in the next 30 years, this wouldn't need to be a problem.

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    $\begingroup$ How does one laser-blowtorch parry another laser-blowtorch? $\endgroup$ – Samuel Dec 14 '15 at 19:43
  • $\begingroup$ With some imagination, you could conceive of a material formed as a rod in the core of the plasma with a cover at the end which "blocked" the plasma from continuing to the ceiling. You'd have to have a material which never melts at the temperature of the plasma while simultaneously retaining the plasma's effectiveness. If these criteria were met and it had sufficient impact strength, it would also answer Samuel's question about parrying. $\endgroup$ – The Anathema Dec 14 '15 at 19:52
  • $\begingroup$ @Samuel Magnets. Specifically the magnetic fields holding the plasma in place would push on each other and/or deflect the plasma. It's admittedly the hardest effect to replicate, but better than nothing. And it's a plasma blowtorch, not laser. Laser would be more than useless for a sword. $\endgroup$ – AndyD273 Dec 14 '15 at 20:10
  • $\begingroup$ @AndyD273 Wouldn't it attract just as well on the opposite side of the blade? $\endgroup$ – Samuel Dec 14 '15 at 20:13
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    $\begingroup$ "I saw your laser sword, only Jedi carry that kind of weapon." - Anakin Skywalker referring to light sabers specifically as laser swords in The Phantom Menace. I know it was crap, but it's still canon. $\endgroup$ – Samuel Dec 15 '15 at 6:10
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An idea came to me while thinking about the "how do you make the blade stop where you want it" problem.

If you were to create a localized magnetic field (it would have to be quite strong).

If you slightly modify the saber to include a cap of sorts...

enter image description here

So the longer black section is the hilt, then blue blade then a black cap that would act as a reflector and create a loop back down to the hilt. Magnetics could be used to hold the cap in place.

You wouldn't probably be able to use it to stab...unless you have a sort of super material that can be magnetized and hot enough to burn through people doors etc. For reference in the 1500 degrees (F) range 1080 spring steel is no longer magnetic and wouldn't burn through metal...well not thick steel doors anyways...you could always go to japan and burn right through paper doors though.

The part I am not even going to attempt to explain is the power source. The amount of power you would need to generate to maintain a lightsaber blade is immense...there are some estimations out there somewhere. Try here

Point is you are going to have to create an arc reactor technology ala Iron man to make it feasible and that is magi-tech so you are going to have to handwave the power source...and the blade stoppage (super material mentioned above) at which point you are basically hand waving the whole thing so why bother explaining...

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  • $\begingroup$ Another problem with using lasers, besides needing the reflector, is that you wouldn't see the beam unless you're fighting in a dusty/foggy area with lots of particles in the air. You could get around this by making laser swords the traditional dueling weapon at raves I suppose. $\endgroup$ – AndyD273 Dec 14 '15 at 18:12
  • $\begingroup$ Right: the end can be held with superconductive flux pinning. $\endgroup$ – JDługosz Dec 15 '15 at 0:12
  • $\begingroup$ @AndyD273 Actually, it depends on the power of the laser. Though a real problem, would be cutting thru reflecting surfaces. :D. $\endgroup$ – Physicist137 Aug 22 '17 at 14:42
  • $\begingroup$ @Physicist137 Hmm, from reading that, it isn't so much a power thing as a it is a wavelength thing, being a wavelength that excites the sodium ions in the atmosphere. I'm sure they are powerful too. $\endgroup$ – AndyD273 Aug 22 '17 at 19:38
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This is actually entirely possible. I would like to propose a very simple mechanism that would naturally result in a light saber.

All you would actually need is a very powerful, focused laser beam. If this laser beam is powerful enough, it will naturally plasmize the air it strikes. This is called the blooming effect.

The thing about this beam of resultant plasma is... It's opaque.

Now, often, we don't want the blooming effect. Scientists have gone to remarkable lengths to avoid the blooming effect, pulsing powerful lasers on and off every femtosecond, so that the plasma has time to get out of the laser's way and the laser isn't blocked by it.

But... For a light saber... The blooming effect would be perfect. A really, really powerful laser would make a beam of plasma, which would in turn block the laser, limiting it's range to about the length of a light saber blade.

I will also note that this system would absolutely be able to make good use of a focusing crystal.

The resultant device would require more power than we can fit into a device of this size in our current stage of development... But everything else is already quite attainable for this device. We could absolutely make a light saber if we had all the required resources for the next thirty years.

There are perhaps two drawbacks to this method:

1) I think you probably knew this, but a light saber is quite impractical. If you had a power source capable of causing thermal blooming and small enough to fit in your hand, you could slightly modify your light saber's laser to pulse on and off every femtosecond, and suddenly the light saber's blade has near infinite length and is a deadly plasma gun. Attach an electrode to the plasma arc and suddenly it isn't just a plasma gun, it's a thunderbolt gun.

2) There is one aspect of light sabers that this system doesn't quite replicate. When two blades constructed in this way collide, they would likely pass right through each other. At most there would be a small blast of plasma as they collided, but they certainly would not bounce off of each other. This issue, however, I suspect is actually impossible to solve if you want to stay within the realm of real physics.

That being said, a light saber is actually scientifically plausible. I doubt the makers of star wars had any clue of that fact, but nevertheless, it's doable if you have the resources.

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I have serious doubts as to how well this fantastical notion of mine would work as a reasonable lightsaber blade however I thought perhaps maybe I should input something different than the standard, it's a plasma blade answer.

My idea is to make the blade out of a powerful electron beam. Electron beams are beams of electrons fired out of a particle accelerator of some sort.

Now to figure out a way to miniaturize an accelerator that small is an exercise for the author of the story, however electrons do have the advantage of requiring less energy to accelerate than their other particle beam kin such as proton and neutral beams. Other forms of particle beam would either be too complex or power hungry, or too long range.

For example, a proton beam would require the stripping of protons and electrons from hydrogen gas, and neutral beams would need both a proton and an electron beam combined. Whereas electrons are abundantly available in the form of electricity.

Electron beams have high dispersion and are generally quite short ranged as a result. Perfect for our blade as it would mean that the particle beam would not extend too far from the hilt and could be focused/defocused to achieve longer and shorter ranges.

However there is the issue that natural dispersion might not be able to keep the blade from extending too far from it's source, but since electrons can be manipulated by magnetic fields you can perhaps even cause the beam to loop back to its emitter, and be recycled.

Now assuming you work out all of the kinks of the design the weapon would have the following properties:

-Its damage would be far more devastating than any mere plasma beam as the electron beam would be bombarding it's target with a stream of high velocity electrons that not only transfer high heat to the target potentially melting it, but also the millions of tiny electrons slamming into it's molecular structure at relativistic velocities would also cause kinetic effects at the microscopic level that would blast a hole through it. This has the added effect of being able to ablate away quicker at even the most heat resistant materials.

-As the electrons collide with air molecules they'd create light and while that wouldn't look like or resemble a normal lightsaber, they'd arguably look cooler as they'd look like crackling blades of lightning and most likely sound like it as well. However also the sound of the accelerator in operation could generate a low hum. Keep in mind the blade would only glow in atmosphere.

-When fighting with these blades assuming the electron beam generated by the blade is strong enough the blades would repel each other. This is because particles of like charges repel each other. So two electron blades would bounce off one another.

-They are retractable, because you simply need to turn them on and off and they can be deployed in seconds. Provided the power source can discharge quick enough.

However they have two huge disadvantages:

-they emit deadly radiation. When the electrons strike an object they do it so forcefully it emits gamma or x-rays. This could kill the wielder if they aren't properly protected, and it would tend to fry any electronics it got too close to. However, I'm not certain how bad the dose really is, so maybe it might not be immediately fatal but cause cancer in long term.

-It can be redirected by magnetic fields, meaning that an object shielded with a negatively charged field could deflect it. However, it isn't exactly practical to walk around wearing a magnetic field harness strong enough to stop something if this power level, so not likely to be exploited.

To get around the problem of the deadly radiation you could potentially assume that the people wielding it are descendants of space colonists who were genetically modified to withstand this sort of radiation. Or it was developed by a species who wasn't overly susceptible to it. Or perhaps have the wielder wear a special protective suit.

Or perhaps you could make it into a plot device, that the hero only draws their weapon in time of great need because it takes a toll on their health.

However if anyone knows a way to keep the wielder and bystanders safe from radiation from this weapon. Let me know.

You could perhaps use insane magnetic fields to control the magnetic spin moment of the electrons causing them to reflect any harmful directly back into the emmitter to be absorbed by a small standoff plate of heavy metal. But this would need insane power budget and could potentially not be workable as it hasn't ever been done with electrons. However if done it could reduce the radiation output to sustainable levels safe for creatures nearby.

In all if a few fundamental challenges are met it could work as a surrogate for a lightsaber.

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