so evidently normal guns exist in star wars (called “slugthrowers” because of course) and they’re apparently super broken and extremely useful because they go right through shields designed to deflect energy weapons and if a jedi tries to deflect them with a lightsaber the bullet just melts and turns in to an equally lethal spray of molten metal 

imagine you’re the most badass sith in the universe and Some Dude With A Handgun challenges you and you’re just like “heh… primitive weapons… bring it on” and he shoots you and you suddenly get splattered with a shower of molten metal and you fucking Die 

So, you know why science fiction has people using laser weapons? I mean, other than them being all cool and science-y, I mean?

So, a lot of science fiction, especially back in the day, takes place in space–on space stations, spaceships, that kind of thing. Places where you really, really don’t want to go around accidentally poking holes in things like, say, the walls.

And you know what firearms are really, really good at? Making holes in things.

Now, lasers are also good at burning holes in things–but they have an interesting drawback. See, when you hit something with a bullet, you make your hole by pushing the matter you struck in and sideways. When you hit something with a laser, you make your hole by heating the matter very quickly, making it evaporate. Things tend to expand when they evaporate–you create a puff of Stuff Particles that (and this is important), goes out and sideways. Right into the path of the laser, partially blocking the beam. You can still drill your hole, but it’ll be less efficient.

Solution: fire the laser in pulses instead of one solid beam, giving the vaporized Whatever time to clear out before the next pulse hit. Of course, how long it takes the Whatever to clear depends partially on the strength of the laser and partially on the substance you’re shooting it at–but that’s okay, you just give the laser different settings for shooting different substances.

In other words, it’s entirely plausible for a laser pistol to have a setting that makes holes in people very efficiently, but isn’t very good at making holes in metal at all–exactly what you want the security officers on your spaceship to be using.

(None of this has to do with Star Wars, of course, because Star Wars is the point where everyone realized that science fiction really is just fantasy with a robots-and-spaceships skin applied, but it’s why hard SF stories from the first half of the 20th century had people using laser pistols, and ultimately that’s why laser pistols became part of that skin.)

And, at least for the ships, ostensibly the speed difference was significant. Ammunition, also.

Oh yeah, for ship-to-ship fire the advantages of lasers are (1) they’re much much MUCH faster than anything you could fire out of a cannon, (2) they have RIDICULOUS range and accuracy (not that this matters in most TV and movies, since those usually have space battles occurring at distances comparable to trying to punch someone while you’re standing on their toes), and (3) you don’t have to carry ammunition for them, making your ship that much lighter and thereby making more room for fuel.

Although MOST sci-fi seems to represent lasers as glowy packets of light traveling at the speed of smell, which is twelve kinds of wrong. Good lasers would be invisible in space until they hit something, and given the aforementioned point about metal vs. flesh there’s little reason to pulse them. Especially if one had a big battery, it would be more effective to turn them on for as long as practicable in order to drill through shields/armor/enemy hulls. The key would be having effective heat sinks to enable them to not overheat, as well as big snazzy power supplies. 

Actually that right there is a good reason to fire in bursts–heat. Because it gives time to transfer heat away from the laser components between bursts, you can fire a much more powerful laser without melting the gun than if you fired it continuously. Also if your enemy is smart they’ve sandwiched a layer of something that absorbs heat well and evaporates into something reflective–water, for example–between layers of hull metal, so the cloud-of-evaporated-stuff issue could still come up.

But yes, heat sinks in general are a huge problem for large spacecraft operating for long periods–the only way to shed heat in near-vacuum is by radiation, which is very, very slow.

Another reason to use lasers instead of the hypothetical space cannons would be kickback. Modern battleship artillery has this problem; the ship has to be in motion when the artillery is fired, or the ship capsizes. That sort of kickback in the vacuum of space with little planetary gravity would be devastating.

Although that also gets us to one of Niven’s Laws–the usefulness of a reaction drive as a weapon is directly proportional to its efficiency as a drive.

A plasma cannon is just a really powerful ion drive with a narrow angle of exhaust–your weapons can double as maneuvering thrusters. The downside is they HAVE to double as maneuvering thrusters.

(This is even true of lasers, although light pressure is very tiny compared to the energy of the beam, whereas the kickback from a cannon is exactly equal to the energy of the projectile, so even in vacuum and microgravity you can usually ignore laser kickback.)


One of Niven’s stories involves hostile aliens encountering a human ship for the first time. Their telepath scans and learns that they have no weapons and are entirely nonviolent.

Aliens attack; ship turns around and fires up its photon drive at them. Turns out “photon drive” means “we fire a laser out the back that can melt a moon to slag,” and the reason humans stopped making weapons or practicing violence is that we got too good at it…