Are real life lightsabers possible? Science explains

Nothing is quite as iconic of the Star Wars franchise as is the lightsaber. A weapon wielded by force-sensitive being of good and evil intent, the lightsaber symbolizes the transcendent nature of the peacekeeping Jedi and their dark counterparts, the Sith. It’s a sword made of pure energy that exerts enough power to slice through metal and flesh with a single effortless stroke, and like all provocative science-fiction technology, has been thoroughly dissected time and time again by both nerds and scientists alike. The release of this winter’s latest Star Wars film, The Force Awakens, presents an excellent opportunity to once re-examine this fantasy amidst contemporary technology.

According the Star Wars lore, lightsabers are constructed by Jedi and Sith trainees during their apprenticeship. The color of the beam is dependent on the color of the specific crystal placed within the hilt of saber, to act as a sort of focusing lens. Standard blades are approximately 4 feet (1.2 meters) long, but some lightsabers are doubled hilted, and oscillate in both directions to create a much longer and deadlier device. In the upcoming film, we even observe a unidirectional lightsaber the length of Scottish claymore (55-60 inches).

Since lightsabers are able to slice through metal and bone with the same level of difficulty as slicing through air, as well as melt large amounts of metal with ease, the weapon must contain a powerful yet compact energy source. This presents us with a couple of mysteries:

1. What type of substance is capable of producing such a high-energy beam of optical light?
2. Why doesn’t this high-energy weapon radiate outward and incinerate the hand of its wielder?
3. How is the wavelength contained within a fixed length?

Although the name “lightsaber” implies that we’re dealing with a laser weapon of sorts, we know this to be untrue given two important characteristics exhibited by lasers. First and foremost, lasers do not have a fixed length — as is demonstrated by all laser pointers. Secondly, lasers are essentially invisible unless they’re are scattered by air impurities like dust particles or fog.

A more believable scenario would that lightsabers beams are made from matter’s fourth state of being: plasma. Plasma is formed by ionizing gas to strip, a process which causes the substance to glow, just like a real lightsaber. The plasma found in stars is able to produce heat ranging in the thousands of degrees, but the plasma we’re most familiar with – that within fluorescent light tubes – is cool to touch and incapable of melting anything; even if the temperature of this particular plasma was raised, its low density would prevent the total heat energy from being very high.

There are, however, some forms of plasma that can generate a substantial amount of heat, such as the thermal variety produced by the plasma cutter, a device that ionizes certain gases between two electrodes using high voltage current to create a high temperature thermal jet of plasma that delivers enough heat to melt metal. This occurs because plasma is electrically conductive and conveys enough electrical current to the target material to heat it up and melt it, but technically speaking, the device is less of plasma cutter and more of an electrical arc cutter, since the plasma functions more like a conductor that permits the electrical current to flow through it and do the dirty work.

So if the plasma cutter is capable of melting metal, does this mean it could serve as the technical foundation for the lightsaber? Given that plasma is a gas that expands and cools, something else is needed to contain the gas within the shape of a beam.

This is where magnetic fields come in. Recalling that plasma is primarily composed of charged particles, magnetic fields should theoretically be able to contain it within a finite space. As it turns out, there’s some very promising technology in development capable of containing plasma within magnetic fields for use in nuclear fusion. The resulting beam is both very hot and very dense, just like a lightsaber.

Yet this doesn’t explain why clashing lightsabers act like solid objects; magnetically contained plasma beams should pass straight through one another. One possible solution is to use a solid core that’s resistant to extremely hot temperatures, something like ceramic.

Ceramic can withstand high temperatures without melting or softening, but a solid ceramic core is brittle, and also sticks out, thereby defeat the purpose of the lightsaber being self-contained within the hilt. Perhaps the core can unfold from the hilt in similar manner to the plastic toys, but again, the substance is brittle and may shatter after constant impact.

How closely does this mirror the abilities of Star Wars’ lightsabers? Well, there still plenty of design flaws. For instance, the plasma produced by the cutter would have to be extraordinarily hot to remove an arm with a single quick cut, or to heat up and melt a massive metal door, as was performed in Star Wars: Episode 1 – The Phantom Menace.

Don Lincoln, senior scientist at U.S. Department of Energy’s Fermilab, explains that if we were to assume the door was made from steel, we can approximate the saber’s energy output by observing how long it took the saber to melt it. Lincoln suggests this figure sits around 20 megawatts (MW) of energy, about as much energy as is needed to power 14,000 average homes in the United States (given the average household consumption rate of 1.4 kilowatts).

Other than the fact that such a condensed and powerful energy source is obviously outside the bounds of our contemporary technology, one could assume that if this energy output were produced by plasma, then it’ll be unbelievably hot — to such an that the heat’s infrared radiation would instantly scorch the wielder’s hand. We don’t have a means of creating the kind of force field needed to contain this level of heat.

Nonetheless, it’s amusing to speculate on how close contemporary science actually comes to achieving the science fiction technology we’ve dreamed of for decades. A self-contained high-heat plasma sword is best lightsaber we can do, and even this is reaching.

Source: Space.com