The lightsaber is arguably the coolest sci-fi weapon ever imagined. But actually inventing it has proven to be a lot harder. Turns out it's incredibly difficult to harness the power of light in any way even roughly resembling the fabled laser swords. This righteous flamesaber is about as close as we can hope to get.
Built by YouTuber , the device looks like a lightsaber, but in practice it's more of a flamethrower, using butane as a propellant to fire out a jet of flaming methanol/acetone mix. The result isn't even a fraction as powerful as a true lightsaber, but it looks like one and can set things on fire at least:
The challenge of creating a device that looks and functions like a real lightsaber has long been the subject of practical and thought experiments. The trouble is that solutions that can burst out from a handheld device and terminate just a few feat away tend to be weak and flame-based like this saber. The problem with actual lasers and beams of light is that they don't just stop, and a steel-slicing laser sword of effectively infinite length is, well, it'd be pretty hard to use.
Some proposed solutions to the infinite laser problem include adding some sort of mirror to the end of the blade (which would make stabbing a non-starter) or just abandoning light and lasers in favor of something like plasma. Maybe the most compelling idea is , or a device strengthened by a telescoping baton that stays hidden beneath the glow. But then there's the problem of fitting a super beefy and basically infinite power source inside tiny handle and, needless to say, it's not really possible.
But at least this flame saber her meets the basic and most important visual critera of extending out of nothing and then stopping a blades-width away. We'll have to stick with that for swinging around, and maybe one of these for really cutting through stuff.