We had a gap at the end of Lecture 12 so Richard gives an unplanned and impromptu talk about some of the contributions of the amazing thinker Alan Turing. So much to say, so little time, such fast talking. We chat about 3 different major contributions he made to the world – his decryption work during WWII and the Engima Machine; his abstract model of a computer (the Turing Machine) and what things can be effectively “computed”; and finally, briefly only, his thoughts about what it is to be human and the difference between humans and computers – the Turing Test. Alan Turing is a key figure in the development of computing, indeed if I had to pick just one thinker who was the most amazing he’d get my vote. Richard promises to talk about the Turing Test in more depth in the next extension lecture. Also comes up: Epimenides paradox, non computable functions, the halting problem, U-559, Colin Grazier GC, Anthony Fasson, GC,Tommy Brown, Blade Runner, CAPTCHAs. Errata: My memory was about as reliable as usual – I said Tommy stayed outside in a boat but i’ve since read that all three swam across and went into the U-559. Humbling bravery. I’ve also since realised that Colin Grazier was from Tamworth in the UK, not the Tamworth in Australia as I had always thought (why are so many English places named after Australian towns?) Finally, something which actually I did know but still managed to get wrong – the important material salvaged was not a cypher machine but quantities of data …