"Impossible" Technologies #2: Light Swords
Light is fascinating. As a fundamental constant in our universe, it is impossible to conceive what it would be like without it. Light is not just visible light - the wavelengths which allows us to see all that’s around us. Light is heat. Light is radiation. Light is life.
If some creators of high-tech weaponry have their way, light could be condensed into a sword and used for dishing out death as well.
And maybe - in a possible future - the technology will become condensed enough to allow the use of lasers to be held in your hand… like a sword. To battle other people also wielding these laser swords, light swords… or lightsabers.
But does having a sword made of light even make sense in a universe without the Force? Is it possible to construct a light sword? Do the laws of physics and chemistry even allow such a thing to exist in any meaningful way?
Fun fact: Lasers are used far more often than you probably realize. Barcode scanners in supermarkets, retail stores, bookstores - just about any place in the world where you can buy a product - use helium-neon lasers to scan barcodes. Laser Tag use infrared lasers to trigger those heavy vests you are told to not run around in but do anyway (it’s a very safe firearms combat simulation sometimes - you gotta run). Most forms of cosmetic surgery, from eye treatments to teeth whitening, utilize lasers in one form or another. Optical mice, such as the one which is sitting on your desk at home or work, use infrared lasers to track their positions and simulate that on your monitor with the mouse cursor.
All of these examples ignores the myriad of industrial and military applications of laser technology. Let’s explore those since that will bring us closer to our fabled sword.
Our laser sword can cut through just about anything, from metals to organic beings. To get a beam of light that intense you need energy. A lot of energy. Fortunately for us, the concept of using light to cut things - whether that’s surgically or through slabs of steel or concrete - is not new. Lasers used for industrial cutting applications are usually large pieces of machinery designed to run materials through them to cut sliced into smaller pieces.
However… there’s one big problem with lasers: they don’t want to stop going forward once they are powered on. If you ever used a laser pointer you’ll notice that the laser only ends once it hits a wall or similar object - otherwise, it’ll keep going into infinity, the laser light spreading itself out into a wider and wider cone over vast distances.
If our laser sword actually isn’t, well, a laser, then what could an alternative be?
Plasma Brings the Heat
If lasers are out, then plasma is in. What is plasma? In the universe all matter are usually in one of three states: solid, liquid, or gas. The state that matter is in depends on its temperature. Given enough heat, matter will shift from one state of matter to the next. For example, as temperatures rise, solid blocks of ice become liquid water; get hotter and that liquid turns into a gaseous water vapor. However, if you keep cranking up the temperature, that gas becomes the fourth state of matter: a plasma. At that point, all the electrons around that matter’s molecules are stripped away by the intense heat, charging them with intense amounts of energy. This process, called ionization, causes matter to glow. Fluorescent lights are an example of plasma in everyday life.
But why plasma? Here’s the kicker: plasma isn’t light which means it can be contained. In addition, the nature of plasma allows it to be manipulated by magnetic fields thanks to the charged particles. According to one article by Scientific American, these facts about plasma could allow us to, in effect, create our sword.
Are Light Swords Possible?
So where are we with all this? If we use plasma we could theoretically manipulate it via magnetic fields to produce a tube-shaped beam that would be hot enough to cut through just about anything. However, plasma is still not a solid, so there wouldn’t be any plasma swords clashing together - they’d just pass through each other as if they weren’t there.
There’s still one area which I haven’t addressed, in part because there’s no realistic answer for it with both present and near-future technology. How the heck would we power the thing? Wookiepedia mentions the use of a “kyber crystal” as the lightsaber’s source of power… so…
The same Scientific American article tackles this best:
“…in ‘Star Wars: Episode I – The Phantom Menace,’ Qui-Gon Jinn sticks his lightsaber in a heavy blast door, first making a long cut and then simply melting it. If you watch the sequence, assume the door is steel, and time how long it takes to heat up the door and melt the metal, you can calculate the energy the saber must have. It turns out to be about 20 megawatts (MW). Given an average household power consumption of about 1.4 kilowatts (kW) at all times, the power draw of a lightsaber could run 14,000 average American houses until the battery ran out.
“A power source of that density is clearly beyond current technology, but perhaps we can grant that the Jedi have advanced technology. They do have faster-than-light travel, after all.”
I’ve already tackled the very popular (and one of my favorite) trope that is faster-than-light travel, so we don’t need to go down that rabbit hole! But it doesn’t take an engineer to realize just how energy-intensive our sword would be, especially if it’s designed to cut through literally anything. There’s just nothing within our understanding of power plant miniaturization or power generation which could allow such a sword to exist.
The amount of energy required to power our sword also ties into another serious problem: heat. As I described earlier, the state of plasma is reached by achieving very high temperatures. The hilt of the sword would have to be made of an unknown material - one with a very high melting point - to allow a handler to simply hold the sword in their hand. But then… there’s heat radiation. You’d be killed instantly the moment you flicked your lightsaber on due to the intense heat put off by the plasma emanating just inches from your body. Again, there are theoretical technologies at work here of which we have no explanations or ways to address.
Until the above challenges have real-world solutions, the laser sword/plasma sword/lightsaber will be, to us, a device that is - in a word - magical in nature.
Are there any particular technologies or concepts in fiction which I should review? Share your answers below!