Confessions of a researchaholic

October 24, 2009

Schrödinger’s cat

Filed under: Imaginary,Real — liyiwei @ 4:06 pm

When I was a kid I have been deeply fascinated by theoretical physics (to the point that I was propelled to pick up college level calculus and physics around age 15), and a recent article in Economist reminded me of one of the questions I had in my mind a long time ago.

Here it is. If someone opens the box containing Schordinger’s cat without my knowledge, what will the cat’s existence to me? Is it still a quantum superposition (i.e. the cat is dead and alive simultaneously), or it will collapse into a definite probabilistic state (i.e. the cat is either dead or alive with a certain probability, but not both)?

I never ended up pursuing theoretical physics because I opted for a more practical major in college that would allow me to “hack” things, so I still do not know the answer to that old question. But now I think for all practical reasons, the cat (or any macroscopic object) is very unlikely to be in a true quantum superposition for a very simple reason: it is simply too macroscopic to be devoid of quantum disturbances that act as probes to collapse the quantum states. Thus, for all practical purposes, the intriguing situation is unlikely to exist; the cat is either dead or alive, but not both.

Growing old does not necessarily make one wiser, but likely more pragmatic.

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