Blockchains

Ownership on the Bitcoin blockchain is determined by a pair of cryptographic keys. The first, called the public key, resides in the blockchain for anyone to see. The second is called the private key, and its owner keeps it safe from view. The two keys have a special mathematical relationship that makes them useful for signing digital messages. Here’s how that happens: Helmut takes a message, combines it with his private key, does some calculations, and ends up with a long number. Anyone who...

 Schrodinger's Cat as a Lock for a Box

Quantum mechanics claims that there is no definite cat in the box, only a ghost, a superposition of a live cat and a dead cat. That is, until we open it and look. A measurement will collapse the system into one state or the other. So goes Schrödinger’s thought experiment. It is completely wrong, of course. A cat is a macroscopic system, and there is no mysterious intervention by a magical observer needed to make it live or die: just its interaction with the rest of the Universe, a phenome...