More Science of Star Trek: Phaser Edition

The puzzling technology of high-tech weapons

As a followup to last week’s discussion of the new Star Trek movie trailer, let’s spend a few more minutes on this most appealing of themes. Now remember we have nothing but affection for the phenomenon of Star Trek, and the creators of the various series, movies etc. sometimes really give it a shot with trying to connect the technology to ideas in the forefront of modern physics. Where would we be without anti-matter reactors, the warp drive, and inertial dampers, to name a few?

However, I’ve always found amusing some of the simple oversights — well maybe not exactly oversights, but somewhat puzzling technological limitations — inherent in the show. For example: Why does the artificial gravity (however that may work) seem to be always oriented in a sort of absolute “downward” direction? Because of this, whenever the Enterprise is knocked off its plane by weapons fire, everyone falls down the “slope”. Maybe the system just can’t adjust fast enough to changes in attitude, but wouldn’t an orientation continuously directly through the floor be more convenient (and easier)?

Anyway, the video demonstrates one of the major idiosyncrasies of Star Trek. It has to do with those phasers. Formidable weapons, yes? Depending on the settings, they can stun, kill, or even vaporize large objects in a matter of tenths of seconds. They come in convenient hand-held, and incredibly powerful starship-sized varieties. According to the manual, they are a directed energy weapon (no messy projectiles like bullets required) emitting “nadion” particle beams.

Now with all of that going for them why are those phaser beams so gosh darned slow? One of the theoretical advantages of a directed energy weapon is that the pulse travels so fast you can’t react to it. If the beam is electromagnetic radiation it moves at the speed of light (c). Because “nadions” are particles, and assuming they have mass, they can’t achieve the theoretical speed limit of c but couldn’t they move just a little bit faster than the pokey speed we see in the show?

Notice in the video you can see the beam quite clearly moving from point A to point B*. And while I realize that only scenes from the original series are included here, phaser beams on The Next Generation are at least as slow. If we spend some time watching the video we can roughly estimate that a beam covers maybe 5.0 meters in 0.1 seconds at best, giving it a speed of about 50 m/s (112 mph). Since guns commonly eject bullets at speeds of 5 to 10 times that fast, it sort of takes away from the super-high-tech mystique of the 23rd century. You just might be able to dodge that thing — as the characters on Star Trek often do!

*Whether you should be able to see the beam at all is another interesting issue. Maybe as it travels through the atmosphere, a phaser beam is ionizing air molecules, which then emit scattered light, but when the phasers are fired in space we shouldn’t be able to see them at all, except at the moment of impact if the beam is aimed directly at us. (Of course we understand invisible phasers wouldn’t be quite as dramatic.)