History of Maths and x

Watching the sky, you can see the Sun, moon, planets and stars moving above Earth. It is very intuitive to imagine that you are standing still and the objects you are observing are moving above you and this was the view taken by geocentric models of the cosmos. A Greek model, which was dominant in many parts of the world for hundreds of years, had a spherical Earth at the centre of the universe, with the other heavenly bodies orbiting in perfect circles. This talk by Peter Rowlett outlines

Cryptography is the process by which messages are communicated through secret means. Cipher cryptography converts messages by applying some cipher algorithm with a secret key to a plaintext message, converting it into a ciphertext message that cannot be read by interceptors. Cryptanalysis is the science that attempts to decipher these messages without access to the secret key. This talk focuses on substitution ciphers and demonstrates the processes of encrypting and breaking some examples of thes