08 February 2007

Infinity, part 1: Thomson's lamp

Back in the 1950's, the famous electrical engineer James Thomson invented the ultimate strobe light. Instead of flashing at regular intervals, Thomson's lamp (as it was called) would start out flashing slowly and quickly speed up.

The lamp had a button on it. Pushing the button caused the lamp to flash for a total of two minutes, as follows. First the lamp turned itself on. It stayed on for half of the total two minutes (one minute). Then it turned itself off and stayed off for half of the remaining time (half a minute). Then it turned itself on for a quarter of a minute, then off for an eighth of a minute, and so on. Toward the end of the two minutes, it would have been blinking pretty quickly.

The troubling question was, after the two minutes passed, would the lamp be on or off? Thomson was so anxious about the philosophical consequences of his invention that he famously refused to press the button for decades. (The legend is that a physicist friend eventually talked him into it, but there are conflicting stories about epileptic seizures, electrical fires, and divine intervention—I can't make any sense of them.)

So: on or off? What do you think?

1 comment:

ab said...

well I thin that the lamp is on/off
in a quantum superposition state
but when someone (thomson?) observe it
a wave function collapse ensue
this kind of decoherance is the same as the Schrodinger cat experiment