Do Lightsaber Blades Have Mass?

When you think of Star Wars, you deliberation of lightsabers. Right? What could beryllium better, from a movie-making standpoint, than a futuristic sword that lets you make awesome fencing duels similar successful old-time Errol Flynn swashbucklers. (So overmuch amended than watching Stormtroopers occurrence their blasters into walls and ceilings and thing other but their targets.)

Lightsabers travel successful a cosmic rainbow of hues (color-coded bluish oregon greenish for bully guys, reddish for bad) and a assortment of shapes. There’s adjacent a double-bladed mentation successful Phantom Menace. (I don’t privation to commencement a nerd fight—yet—but the champion lightsaber conflict successful the canon has to beryllium the “Duel of the Fates” successful that movie, acknowledgment to the skills and scariness of Darth Maul histrion Ray Park.)

So … precisely what are lightsabers? Of course, they aren’t real, truthful cipher truly knows however they work. Even the characters successful the movies look a small confused astir it. In Phantom Menace, Anakin calls it a “laser sword.” Yeah, helium was a kid, but some Din Djarin (the Mandalorian) and Luke Skywalker besides notation to it arsenic a laser sword—though I fishy Luke was being sarcastic.

Anyway, that’s conscionable wrong: It can’t beryllium a laser. For starters, lasers beams are invisible from the side, truthful you wouldn’t spot a happening unless you staged the duels successful a disco with fog machines to scatter the beams. Second, the beams spell connected forever; they don’t person an end. Third, laser beams can’t clank unneurotic similar swords—they’d conscionable walk done each different erstwhile you effort to parry.

But what is it then? We tin greatly constrictive the possibilities by asking if the leaf has mass. If it’s some benignant of airy (as you’d deliberation from the sanction “lightsaber”), past the reply is no—light, oregon electromagnetic radiation, has nary mass. If we tin find that it has mass, past it’s not light.

This is simply a question we can answer, by analyzing however lightsabers determination erstwhile you question them around. In different words, it’s clip for immoderate physics!

Mass and Motion

Don’t confuse wide and weight. Mass is simply a measurement of however overmuch “stuff” similar protons, neutrons, and electrons are in an object, and value is the magnitude of gravitational unit acting on an object. Here we privation to spot what interaction the wide of a lightsaber would person connected its motion. But let’s commencement with thing simpler.

Instead of a lightsaber, accidental we person a “lightball” made of the aforesaid buzzy substance. Since it’s symmetrical, we tin picture its question without worrying astir rotation. If we privation to determination this shot backmost and forth, we telephone connected Newton’s 2nd instrumentality of motion. This says the acceleration (a) of an entity depends connected its wide (m) and the magnitude of unit (F) applied to it.