No one should have any excuse for not knowing Erwin Schroedinger’s famous thought-experiment about the cat that was both alive and dead at the same time, as a metaphor for quantum states. For those of you who forgot, in short, there’s a cat in a sealed box with a vial of poison, a detector, and a radioactive isotope. If the isotope decays, the detector detects it, breaks the vial, poison is released and the cat dies. If it doesn’t decay, the cat is alive and well. Without opening the box, how do you know if the cat is alive or dead? You don’t…until you open the box and observe the cat, it is both dead and alive at the same time. Don’t worry, though. No real cats were harmed in this experiment. Does all this have much relevance to the review? Why yes. Yes it does. Read on to find out why.

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