Lightsabers are a genius idea: portable, lightweight, activated with the flick of a switch and oozing cool (at least if you’re a Star Wars fan). To create the saber’s shining blade of light, laser technology seems the obvious choice. Laser produces a highly directional light beam which can be used for everything from etching metal surfaces to eye surgery, so why not battling the dark side? Unfortunately, it’s not as simple as it looks. Problem #1: Creating a short blade Probably the most fundamental issue is that a lightsaber’s blade needs to stop short after a couple of feet. But a laser beam, just like any kind of light, never just ‘stops’, unless something in its way absorbs or reflects the energy. A laser-powered lightsaber would therefore be extremely unwieldy, not to mention constituting a real health and safety nightmare. Allow the slightest lapse of attention during a battle and you could accidentally decapitate your best friend or slice off your own toes. One solution would be to cap the end of blade with a mirror to confine the beam, but this would mean that you couldn’t stab anyone. Plus, building a structure to hold the cap in place would take all the elegance and grace out of a lightsaber. Problem #2: Size Producing a high-powered laser beam requires a lot of kit. Although some pretty amazing advances in technology have seen high power lasers shrink in size, you’d also need some kind of cooling system to prevent the system from overheating. This fundamental requirement means you’d be hard pressed to build a light saber that you could physically carry on your back, let alone pull off any fancy sword tricks with. Problem #3: Powering the blade This brings us on to the question of power. Lasers strong enough to do any proper damage need serious amounts of energy, so your light saber couldn’t run on standard batteries. You’d probably have to plug yourself into the mains - which might not go down so well on an enemy ship (even if the ship’s owner was actually your dad). Problem #4: More combat issues Since as we’ve seen, a laser beam is easily reflected, it would be easy for your opponent to shield themselves with a mirror, or even turn your lightsaber’s blade back against you: possibly a bit embarrassing. What’s more, clashing lightsaber blades would be impossible – the beams would just pass straight through each other and make for a very boring duel. Problem #5: Visual and audio effects Half the reason lightsabers are cool derives from their colourful glow and swooshy noises. Unfortunately, a laser beam can’t be seen from the side (unless the air is particularly smoky or dusty – that’s why lasers are always used in conjunction with smoke machines in clubs or concert venues). Just like an oversized laser pointer, a light saber would be basically invisible. Unless of course it was directed straight into your eye, in which case it would probably be the last thing you ever saw. And in the same way that waving a torch around doesn’t make any noise, you’ve guessed it, swinging your lightsaber would be silent. And let’s face it, even Luke Skywalker would look pretty pathetic wielding an invisible and silent sword. In conclusion, lightsabers as depicted in Star Wars will never be a reality. Although advances in technology could perhaps one day solve the power and size issues, the basic problem of blade length really puts a downer on things. Unless in the next 50 years physicists come up with something even better than lasers.
I have been asked on more than one occasion by young innovators to help them make a lightsaber. Truth be told there was a time that I also wanted to make a lightsaber so I'm always up for it. If you perform a Google search for "lightsaber" you are going to get back a lot of results, most of which are to make something that looks like a lightsaber. That's all well and good, but I thought it was about time I dug in a little deeper to find out if it's possible to make an actual device. All danger aside, it would be pretty cool. Thankfully Physics.org looked into it and well, I'll let you read for yourself to see why we are a little ways away from being a Jedi or part of the dark side. Don't give up hope, we were once told we couldn't fly.
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