A Look at the Physics of Lightsabers

Lightsabers. They’re arguably the most important prop in the Star Wars saga. Their brilliant combination of sci-fi tech with their accompanying medieval fighting styles makes them stand out as perhaps the most recognizable weapon in movie lore.

These sabers of light practically make the Star Wars movies what they are, but could you actually make one?

Examining the initial specs, lightsabers are usually around 3 ft. long and are powered by what is known as Kyber crystals, found across the Star Wars galaxy. Their beams are understood to be light or plasma, essentially high energy photons. These two design aspects, the crystals, and limited length photon beam, are what we need to consider as we address the feasibility of lightsabers.

First, the crystals. According to Star Wars canon, these crystals allow a connection to the force and are tied to the Jedi who uses them. They control the color of the saber only after they have bonded with a particular Jedi. That said, these crystals are found on other planets and inherently contain properties beyond our current scientific knowledge. Given the relatively unexplored state of the universe, it’s possible but not likely that Kyber crystals do exist somewhere… So, we’ll leave it at that for now and move on to the beam.

Beams of light or plasma are pretty tricky to contain. You can’t buy a flashlight that only shines 20 feet away from you and then stops completely. This is because photons are rather difficult to stop, thus making them hard to control in midair. The most practical way to engineer this phenomenon would be to place a highly reflective surface, a mirror, at the other end of the beam. Doing so, however, would already be a divergence away from the design presented in the movies. If we really want to push the limits of their design to fit this mirror narrative, we could assume that the sound of a lightsaber turning on is actually in part due to this small mirror extending outward. Yet, all this seems unlikely to coincide with the original design.

Nonetheless, let’s move forward. 

Lightsaber’s beams are very obviously visible light, which presents some problems if we are trying to up the power – what would be needed to create actual lightsabers. Using a light beam would mean essentially a high-powered laser, one that would require a cooling system among other technical factors. Not to mention, if lightsabers were made of high-powered lasers, the necessary power would be high enough to give us the worst sunburn of our lives within milliseconds.

There’s also a major functional problem to light beams, they can’t deflect a shot from a plasma blaster.

Let’s consider the beam to be plasma then. A highly-engineered electromagnetic field could theoretically contain a beam of plasma to 3 feet or so. To do so, the field would have to send the plasma on a highly elliptical path to make it appear saber-like. So, we could make a plasma beam, but can it do other lightsaber-y things?

Plasmas would be hot enough to cauterize wounds instantly and melt metal, just like the movie. It sounds like plasma may be viable! However, our first big problem with plasma sabers comes when we consider dueling.

It is probabilistically unlikely that two elliptical paths of plasma would repel each other like swords. That said, Brian Cox and Neil deGrasse Tyson do discuss a particular trait of high-energy photons that would give some probability to photons repelling each other in the video below.

Cox’s explanation means that there is at least a small chance that a high energy beam of photons, say a plasma lightsaber, would repel another plasma lightsaber, however unlikely that action may be.

Plasma sabers operating under the most probable conditions would be able to be a controlled length, they would appear to be lightsaber-y and there would be a small chance that they would repel a blow from another lightsaber. All this being theory of course.

The second, perhaps bigger issue with a plasma saber would be a thermal one. Plasmas are hot, often millions of degrees and being near one as powerful as a lightsaber would feel like being next to a high-powered oven. To overcome this, we would need to imagine a material with practically zero thermal conductivity to use for the saber grip. To overcome the heat transfer through the air, the best way to mitigate this issue would be to surround the plasma ellipse in an unknown gas capable of alleviating the heat.

Lightsabers appear to be theoretically possible, but they would require the discovery of new super-metals, super-gases, kyber crystals, and advances in our understanding of physics as well. Since we can’t prove that these materials don’t exist, we can’t definitively prove that lightsabers couldn’t exist pending phenomenal discoveries.

So, there’s hope for real lightsabers yet. While no one has made a real lightsaber, people have made projects undeniably close. Check out the videos below to see the forefront of hobbyist saber building technology from the present day in our very own galaxy.

2500˚ Lighsaber

Burning Lightsaber

Perfect Lightsaber Hilt

Making a Lightsaber with Fusion 360

Sources: Nautilus, Physics.org, Motherboard

Trevor is a civil engineer (B.S.) by trade and an accomplished writer with a passion for inspiring everyone with new and exciting technologies. He is also a published children’s book author and the producer for the YouTube channel Concerning Reality.

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