Well, one would be the Shroedinger's cat thought experiment mentioned in the article. The idea that the cat can be alive and dead at the same time, sort of.
From what I recall of my nuclear & particle physics class, back in the day, the basic quantum paradox is that when you get down to the really small things (electrons, say), they aren't exactly in any one place, the way we'd expect them to be. The electron, for example, exists in a sort of probability cloud around a nucleus, until you detect it. And it isn't a matter of us just not knowing where it is until we detect it. It really isn't in any one place, until you detect it there (and then of course, it's automatically somewhere else due to the interaction). The electron, as a particle, is really only a potential particle, when it's not being detected. As in, if you stick a detector into a given region where the electron is allowed to exist, you have an X% chance of finding it there.
The act of finding a particle, and making it "exist" in a particular location, is the "decoherence" that the article is about. The particle no longer exists as a probability field, but as a concrete (err, sort of) particle that you just detected. And according to QM, this only happens when you observe it. So the problem Einstein had was, how come things can still exist in one place, when their particles could be anywhere?
Ok, now I'm summarizing the article. It seems to be down at the momnent, but read it when it comes back up. My question is, we always hear "The Quantum Paradox", but is it a paradox, really? Or just a mode of reality that we're not used to dealing with?
Not the real rusty
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