Why are there no animals with three legs?

If "Why?" is the first question in science, "Why not?" must be a close second. Sometimes it's worth thinking about why something does not exist.

Quantum cats are hard to see

Are there parallel universes? And how will we know? This is one of many fascinations people hold about quantum physics. Researchers from the universities of Calgary and Waterloo in Canada and the University of Geneva in Switzerland ...

Less is more for Maxwell's Demon in quantum heat engines

Over 150 years after the famous Scottish scientist James Clerk Maxwell first introduced the idea, the concept of Maxwell's demon continues to perplex physicists and information scientists. The demon he dreamed up in a thought ...

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