Liz Phair has gone insane

Game theory in movies

The incredibly weird physics of space-flight

Lately, I’ve been debating space-flight video games with my friends. One of the complained that games like Rogue Squadron — an incredibly cool Star Wars-themed game — is weirdly unrealistic. “The ships are in outer space, but they fly like planes,” he argued. For example, when you try to turn, your ship has a big turning radius — even though it’s not pushing against any air. A real space-ship could just instantly rotate itself in any direction it wanted and shove off.

I argued with him, posing the alternative question: Who wants real physics? The whole point of a game is to present you with a version of reality that’s as stylized as a sonnet. In fact, if the game actually represented the realistic physics of the cosmic void, controlling those X-wings and TIE Fighters would be a total nightmare. Space physics are incredibly weird.

That’s what NASA found back in the 60s, when it first tried to do something you’d expect would be quite simple: To dock two spacecraft together. There’s a superb story in last year’s Invention and Technology magazine on this. NASA had a Gemini capsule fly up to an empty rocket casing that was floating in order, and try to dock with it from behind. But, as the astronaut in control found, the physics quickly became awfully strange:

… simply pointing the craft toward the target and firing his rear attitude thrusters did not help him overtake the spent stage, as one would expect. Instead, the distance between them actually increased, as if he were pressing a car’s gas pedal in forward gear and the car was moving in reverse.

This was where Newtonian mechanics kicked in. By increasing his craft’s speed, he had increased its distance from the earth. In this new, higher orbit, the craft’s linear velocity, measured in miles per hour, was greater than before. But its angular velocity—the rate at which it was traveling around the earth, measured in revolutions per hour—was lower. As Kepler had pointed out, objects in low orbits will complete an orbit around the earth faster than those in high orbits, even though their linear velocity is lower.

Thus, by speeding up his spacecraft, McDivitt had made it circle the earth more slowly than the craft he was trying to catch up with. Mission Control had to call off the rendezvous, since McDivitt was using too much fuel. NASA engineers and astronauts extracted a valuable lesson from this mission: It was difficult, if not impossible, to steer a spacecraft merely by eye. The orbital dynamics are so counterintuitive that—combined with the lack of references for judging distances—no human could do the job without help from electronic sensors.

All of which goes to show: Realism is a huge pain in the ass. I’ve never entirely understood people who assume that “realism” is the tautological goal of video games; the more realistic they are, the more fun they’ll be. Quite the contrary! Sure, the Y-wing fighters in these games are as easy to pilot as a Camaro. But I wouldn’t have it any other way. I get enough reality sitting here at my bloody desk, thank you very much.

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I'm Clive Thompson, the author of Smarter Than You Think: How Technology is Changing Our Minds for the Better (Penguin Press). You can order the book now at Amazon, Barnes and Noble, Powells, Indiebound, or through your local bookstore! I'm also a contributing writer for the New York Times Magazine and a columnist for Wired magazine. Email is here or ping me via the antiquated form of AOL IM (pomeranian99).

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