A friend and I were playing Nintendo, the original eight-bit system, and we played Duck Hunt, a game that requires a “light gun.” I was wondering: How exactly does the Nintendo game “know” where you are pointing the gun on the screen when you shoot ducks?!? Very mind-boggling! –Matt
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Here’s what happens. You shoot at a duck, which appears on an ordinary TV screen. The gun is connected to the game console; pressing the trigger blackens the screen, then causes a duck-shaped white target to appear momentarily. If your aim is true, a photo sensor in the gun detects the shift from dark to light, and bingo–dead duck. To reiterate, the TV emits the light pulse and the gun detects it, not the other way around.
But that’s for the gearheads. At the Straight Dope we’re more interested in the deeper meaning of it all. Ingenious as the light gun is, magicians have been boggling minds for years with similar cause/effect reversals. Take the “directed choice.” You pluck a card at random from a deck, then return it. You alone know the card’s identity–let’s say it’s the ace of spades. The magician then displays four cards so that only you can see the faces. None is the ace. She places the four cards facedown in a square. By sleight of hand, the details of which need not detain us, she replaces one of them with the ace. “Pick two,” she says. You do. The magician then discards the other cards (if you picked the ace), or the cards you picked (if not). She points to the two remaining cards and says, “Pick one.” If you pick the ace, she discards the other card. If you don’t pick the ace, she discards the card you picked. Indicating the one card remaining, the magician says, “Turn it over. Is that your card?” Of course it is. You’re amazed and mystified, but as you can see, the trick turns on a simple, unsuspected reversal of cause and effect. (Low light, quick fingers, and a couple beers also help.) You thought you were the active agent; in fact you were the patsy. Understand now? Congratulations. You’ve just passed Marketing 101.
I’ve often wondered why flagellating underwater produces a more horrific odor than an airborne sample from the same batch. –Richard Reneau, assistant director of maintenance, Austin State Hospital
