Friday, February 5, 2010

Three guys walk into a bar

I was reading a popular-science physics book - the chapter on quantum mechanics - when this joke started to seep into my head, growing like an algae bloom across an otherwise placid pond.

"Three guys - call them Dave, Don, and Don's Dad - walk into a bar and start playing pool. Dad shoots a powerful shot toward a corner pocket. The object ball bounces off the two points of the pocket and rockets across the table, sinking into the opposite corner pocket.

Dad smiles knowingly, explaining that he wouldn't have had to shoot that kind of difficult shot except for quantum mechanics. You see, he told the others, had the superposition of the wave function of the balls on the table not been collapsed by being observed by Dave and Don, Dad would simply have been able to place the balls where he wanted them, unobserved.

After all, as Einstein said, God does not play pool with the universe.

A nearby fundamentalist religious dude overheard the conversation and aggressively asked Dad whether he was mocking God. "Oh, no," Dad said, he was only making fun of physics types like Werner Heisenberg, Erwin Schrödinger, and the under-appreciated sage Wilhelm Clerk Skidmorsky. The dude says, "Skidmorsky?" "Oh yes," said Dad. "You mean you haven't heard of "Skidmorsky's mouse?"

Dad explained that the thought experiment involved a mouse placed in a box in which an apparatus had a 50-50 chance of killing it - unless the mouse gnawed through the apparatus first. Is the mouse alive or dead? The answer is: Both! At least until someone looks inside. (Unless, of course, the mouse has free gnaw.)

While Dave and Don were laughing uncontrollably, Dad quietly moved the balls into his preferred eigenstate."


Blame the joke on Sean Carroll, the author of "From Eternity to Here," the book I'm still reading. In that chapter on quantum mechanics, despite his heroic (and successful) striving to explain it all non-mathematically, he pauses to assure readers that: "No animals will be harmed in our thought experiments."


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