Tuesday, June 30, 2009

Quantum beaches

"Quantum mechanics describes what a system might do in the future, whereas classical mechanics describes what it has done in the past." This is a quote attributed to Freeman Dyson in an early 1990's lecture. [CC, p.272]

Right or wrong, every now & then you hear a line that brings ideas together in a provocative way. One of the central quirks of quantum mechanics is that things are undecided until an observation is made, but it's not really clear what constitutes an observation. Surely there isn't a list of "valid devices for observation."

What if the elusive observer is universal? What if it is simply the arrival of the present moment? In other words, all quantum waves collapse at the present moment, making the past a deterministic record of what has happened. The waves crash on the quantum beach.

There are one other big idea here. One is the illusion(?) of the flow of time in one direction. This is now solved ... once the quantum waves have crashed, they are irreversible, there's no going back to an unobserved state. Water doesn't form itself into waves and rush off into the distance.

Food for thought.

CC. Ian Stewart & Jack Cohen, "The Collapse of Chaos" (Viking Books, New York, 1994)