The Secret History of Codes & Code-breaking.
Simon Singh takes us on a journey through ages: from the cipher of Mary Queen of Scots, through Enigma, public key cryptography to quantum cryptography. He reveals the history of code making and code breaking.
The Code Book is not just about history. It is a study guide, too. Everything is illustrated with examples, formulas, and diagrams. Simon has a gift of describing frequency analysis, one way functions and even quantum computing in an simple way.
The Code Book is a great read. Highly recommended.
There is one thing in The Code Book, which may be interpreted as a proof that we live a computer simulation. It is about Thomas Young's experiment with a light source, a partition with two slits, and a screen. That experiment shows the wave nature of light. Waves of light reinforce or cancel each other producing multiple stripes on the screen. But nowadays we can send just one photon, wait for a minute, then send another, again wait, send another and so on. In this case, should we see multiple stripes on the screen or just two? Each photon that we send has no other photon to interact with, so it should behave like a particle and just go through one of the two slits. There should be only two stripes on the screen.
Simon writes: "However, for some extraordinary reason, even with single photons the result on the screen is still a pattern of light and dark stripes, just as if photons had been interacting." There are two scientific theories currently that try to explain it: superposition and multiverse. Either the photon passes through both slits simultaneously and then interacts with itself - that's superposition, or the universe splits into two which interfere with each other - that's multiverse.
Well, I'm a programmer, and from my point of view it looks like a silly bug. If I was designing the universe, I could easily make an error of assuming that the characters in my world would never get smart enough to send a single photon, so I would take a shortcut and compute the pattern as if photons were sent continuously. It's a simpler explanation than superposition or multiverse, isn't it? :-)
I need to learn more about photons.