We’re closer than ever before to creating a real lightsaber

 Have you ever dreamed of being a Jedi? Armed with a sleek weapon for a more civilized age, many of us dreamed of cutting a bright green (or blue) streak across a galaxy far, far away. Disney even issued a patent for one such device in 2018, though "a sword device with a retractable, internally lit blade" doesn't quite conjure up images of cutting through doors or armoring droids.

This begs the question in this Star Wars day: is it really possible to build a lightsaber, and if so, how far are we from holding it in our hands and whistling 'Duel of Fates'? The answer might surprise you – but first we're going to have to figure out exactly what we mean by lightsaber, and learn some science along the way.

So what would you need to make a lightsaber as we know it?

A lightsaber has to tick six basic boxes: it has to light up and glow when used, it has to be able to cut through an object, it has to be retractable, it has to make a distinctive hissing sound, you have to be able to step over them. in combat, and most importantly, must follow the rule of cool. The bad news is that not all of them are possible at once - yet - but the good news is that they are all already possible individually - at least in theory.

While we don't have access to Kyber crystals in our galaxy, the laws of physics are more than a good substitute. The first problem that needs to be solved is the light and the blade, and for this we can use the physical principle of laminar flow. This is when all the components in a gas or liquid move in exactly the same direction without bumping into each other, a bit like using a shower head.

This then allows us to use any kind of mixture of liquid fuel and oxidizer to create a single high intensity beam of cutting power. While we may be tempted to use rocket propulsion and fuel, the reality is that something as simple as liquid propane used in barbecuing is more than enough. With these ingredients; BBQ fuel and a laminar flow nozzle, it simply becomes a matter of tuning the fuel mixture and valves to get a retractable blade. For the iconic wosh, it's a matter of building a circuit with a speaker and accelerometer to make the famous lightsaber sound when swung.

The final touch is the famous coloring of the blade. While Wien's Displacement Law states that the temperature of an object is directly related to its color, it does not give us the intense color that we usually associate with this aspect of the Star Wars universe. Instead, by introducing a small amount of specific chemical compounds at the end of the hilt, we can influence the color. By burning strontium metal, for example, we can achieve that iconic Sith red, or potassium chloride for Mace Windu purple. The lightsaber's intense glow will come from the heat of the plasma generated by the mixture of fuel and oxidizer.

That still leaves us with the problem of being able to beat them in a duel, which requires resistance to temperatures high enough to melt the noise doors. Currently, the material with the highest melting point is tantalum hafnium carbide alloy (Ta4HfC5), which melts at an incredible 3990°C. Unfortunately, this is the approximate burning temperature of liquid propane. When you make something retractable, you also introduce small weaknesses in the metal, which increases the likelihood of cracking and failure. Therefore, even when working with materials resistant to ultra heat, proper care is needed so that the material does not fail due to stress.

This means that any lightsaber construction plan you can tackle must include not only a heat-resistant material, but also a sturdy one.

How close are we to wielding the Jedi's favorite weapon?

We have two major stumbling blocks when swinging around a screen-accurate lightsaber: fuel and combat. Assuming we still follow the laminar flow principle mentioned above, we can achieve an incandescent steel melting beam by finding a fuel with a high density and high burning temperature. We want the first to be able to store the fuel in a nice little rechargeable bottle like a battery, and the second to be able to melt through the doors of any rebels.

Acetylene or rocket kerosene might be good candidates, with acetylene being used in plasma cutters and kerosene being the one that got men to the moon in the Apollo program. However, they still don't quite fit the bill. Acetylene is not dense enough to be stored in a battery, and you would need a large tank of it to power a lightsaber for any length of time. Kerosene, on the other hand, has a relatively low flame temperature, meaning it would be difficult to cut through metal.

Then comes the question of being able to cross the blade, as you need a tough material that can simultaneously handle the stress of high temperature and fight a deadly enemy. My guess for realizing this design would be a central core of a high melting point material such as tantalum hafnium carbide that can be telescoped out by a high temperature flame from the propellant/fuel mixture.

The good news is that modern science is making leaps and bounds in this area. Continued research into high-density fuels, energy-rich fuels, and stress-resistant materials means we are now closer than ever to making a true lightsaber. The only question left to ask is what color do you want yours?