Codes and Demons: Are Quantum Computers Possible?
"This is not a drill! I repeat, this is not a drill!" ...... There's a strange couple of sentences. If you were an alien, plonked down on Earth with only a dictionary in hand, wouldn't those two exclamations strike you as a bit odd? Why repeat what you have just said, particularly when the content is apparently so urgent? Why use so much redundant waffle? Well despite what we might think, an alien would probably not find the repetition of an urgent message particularly surprising. The features of information are the same, regardless of the language you speak, whether that be English, Vogon or C++. The reason for redundancy in language is the presence of noise . Suppose you had one bit of information: a number which might be either valued 0 or 1. And say you wanted to transmit that bit of information to your friend, Alice. But you have to send this bit over a noisy channel. For example, maybe you're sitting in a lighthouse and you flash the light once for &qu