Read an interesting interview with Roger Penrose at Discover Magazine. Found this part fascinating:
So Schrödinger himself never believed that the cat analogy reflected the nature of reality?
Oh yes, I think he was pointing this out. I mean, look at three of the biggest figures in quantum mechanics, Schrödinger, Einstein, and Paul Dirac. They were all quantum skeptics in a sense. Dirac is the one whom people find most surprising, because he set up the whole foundation, the general framework of quantum mechanics. People think of him as this hard-liner, but he was very cautious in what he said. When he was asked, “What’s the answer to the measurement problem?” his response was, “Quantum mechanics is a provisional theory. Why should I look for an answer in quantum mechanics?” He didn’t believe that it was true. But he didn’t say this out loud much.
You would probably know that Einstein was involved in a long running debate about the completeness of Quantum Mechanics. Quantum Mechanics posits that if we measure a particle’s position precisely then we can never measure/know (even theoretically) it’s momentum. Reality is fundamentally fuzzy, said QM. Einstein didn’t like this idea of QM’s stubbornness. QM suggested that Reality is what QM says it is, that Reality is essentially unknowable in its entirety. Einstein’s objection in his own words: “I think that a particle must have a separate reality independent of the measurements. That is an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it.”
Anyho, Einstein and two other physicists worked out an experiment that would supposedly show that QM was incomplete. It’s called the EPR Paradox. To test this paradox a mathematician named John Bell gave an inequality (the inequality said: if both position and momentum of a particle have an absolute value independent of measurement then the equation’s ‘not equal’ condition will hold). Long story short, Einstein was proved wrong. There are all sorts of implications arising from this: physical, metaphysical, spiritual and financial (ok, not the last one). Non-locality is a good one to begin with (Non-locality is the phenomenon predicted by QM that Einstein called ‘spooky action at a distance’ .)