Dion's random ramblings

Tuesday, February 19, 2008

Many world quantum theory, an easy explanation using a multiplay Super Mario game!

This is so cool! Multi world quantum theory explained in a fun way!

The Mechanically Separated Meat blog has created a merged video of hundreds of games played against "Kaizo Mario World" (an insanely difficult homebrew Mario level) and used the resulting video as the jumping-off point for an extremely stimulating and enlightening discussion of the Many Worlds hypothesis in quantum physics. If I had to explain Many Worlds to an eight-year-old (something I expect to have to do in, oh, about eight years), this is where I'd start. I'm especially enamored of the choice of Mario for this, since it's just the right blend of puzzler and jumper to make you want to explore all possible choices (I've recently become brutally addicted to Paper Mario, which now occupies about 10 percent of my brain on a more-or-less permanent basis as a kind of low-grade background process).

This said, tiny quantum events can create ripples that have big effects on non-quantum systems. One good example of this is the Quantum Suicide ?experiment? that some proponents of the Many-Worlds Interpretation claim (I think jokingly) could actually be used to test the MWI. The way it works is, you basically run the Schrödinger?s Cat thought experiment on yourself? you set up an apparatus whereby an atom has a 50% chance of decaying each second, and there?s a detector which waits for the atom to decay. When the detector goes off, it triggers a gun, which shoots you in the head and kills you. So all you have to do is set up this experiment, and sit in front of it for awhile. If after sixty seconds you find you are still alive, then the many-worlds interpretation is true, because there is only about a one in 1018 chance of surviving in front of the Quantum Suicide machine for a full minute, so the only plausible explanation for your survival is that the MWI is true and you just happen to be the one universe where the atom?s 50% chance of decay turned up ?no? sixty times in a row. Now, given, in order to do this, you had to create about 1018 universes where the Quantum Suicide machine did kill you, or copies of you, and your one surviving consciousness doesn?t have any way of telling the people in the other 1018 universes that you survived and MWI is true. This is, of course, roughly as silly as the thing about there being a universe where all the atoms in your heart randomly decided to tunnel out of your body.

But, we can kind of think of the multi-playthrough Kaizo Mario World video as a silly, sci-fi style demonstration of the Quantum Suicide experiment. At each moment of the playthrough there?s a lot of different things Mario could have done, and almost all of them lead to horrible death. The anthropic principle, in the form of the emulator?s save/restore feature, postselects for the possibilities where Mario actually survives and ensures that although a lot of possible paths have to get discarded, the camera remains fixed on the one path where after one minute and fifty-six seconds some observer still exists.

Link (via Kottke)


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