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Name: Unknown
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993


Question:
What is your opinion of quantum mechanics and how it effects our notion of cause and effect relationships? I read that experiments were performed where a change in the wave/particle state of one half of a "baby photon" pair would spontaneously effect the other half. What is up with that? I also read that actual form of the photon whether wave or particle) depended on how we measured it. It is all very odd. Any explanations?



Replies:
So far quantum mechanics seems to be perfectly consistent with a rather extended definition of cause and effect - that no information can be transferred faster than the speed of light. The experiments you are referring to, however, basically prove that quantum mechanics cannot be based on some localized classical theory - that the equations of quantum mechanics really do mean what the seem to mean. For example, that particles (such as photons) have both wave-like properties (such as wavelength and frequency) and particle-like properties (such as position and momentum). The point is that when you start investigating nature on the very small scales at which electrons and photons act, you start running into situations that are very different from the everyday world, especially because there seems to be some inherent randomness in our measurements of some of the properties of this microscopic world - Heisenberg's uncertainty principle is at the center of it all.

A. Smith



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