Comment Re:Crap. All crap. (Score 1) 221
Actually what was shown was that if there are quantum mechanical hidden variables, they must be communicated from one place to another at greater than the speed of light.
Bell's Inequality puts a limit on the correlation of the states of two particles measured seperately, which is different from the prediction of quantum mechanics. Experiments confirm the quantum mechanical prediction.
As an example of correlation, consider two photons produced by the annihilation of an electron and a positron (someone mentioned PET scans earlier). If you measure the polarization of one photon relative to some angle, the other has to be polarized the same in order to conserve angular momentum at the production point. However, according to quantum mechanics, the polarization isn't determined until you measure it (e.g. the photon has equal probability of any polarization), so how does the other photon know what polarization the first one had when it was measured? If you assume the photons have a definite polarization at the point of production, you get Bell's Inequality, which is refuted by experiment. If you assume "quantum mechanics" you get the experimentally confirmed result.
Einstein, along with most other physicists, dislike superluminal signalling (it violates causality), so the hidden variables hypothesis is basically dead.
Going from quantum mechanics to questions of "what's real" or "is it there when I'm not looking at it," however, is slippery, and it's philosophy, not science. The Copenhagen interpretation simply says that the state of a system (represented by a vector of probability amplitudes) changes to one representing a specific value of an observable when the system is measured with a classical measuring device. Assuming that this requires a sentient observer, or has anything to do with "real" or "not real" goes outside quantum mechanics.
Certainly the idea that "thought" can influence a quantum system in a measurable way is, shall we say, "highly speculative."
Bell's Inequality puts a limit on the correlation of the states of two particles measured seperately, which is different from the prediction of quantum mechanics. Experiments confirm the quantum mechanical prediction.
As an example of correlation, consider two photons produced by the annihilation of an electron and a positron (someone mentioned PET scans earlier). If you measure the polarization of one photon relative to some angle, the other has to be polarized the same in order to conserve angular momentum at the production point. However, according to quantum mechanics, the polarization isn't determined until you measure it (e.g. the photon has equal probability of any polarization), so how does the other photon know what polarization the first one had when it was measured? If you assume the photons have a definite polarization at the point of production, you get Bell's Inequality, which is refuted by experiment. If you assume "quantum mechanics" you get the experimentally confirmed result.
Einstein, along with most other physicists, dislike superluminal signalling (it violates causality), so the hidden variables hypothesis is basically dead.
Going from quantum mechanics to questions of "what's real" or "is it there when I'm not looking at it," however, is slippery, and it's philosophy, not science. The Copenhagen interpretation simply says that the state of a system (represented by a vector of probability amplitudes) changes to one representing a specific value of an observable when the system is measured with a classical measuring device. Assuming that this requires a sentient observer, or has anything to do with "real" or "not real" goes outside quantum mechanics.
Certainly the idea that "thought" can influence a quantum system in a measurable way is, shall we say, "highly speculative."
