After two days in Hay-on-Wye at How the Light Gets In, I am back (temporarily) in London, my next gigs (in fairly quick succession) Oxford, Istanbul, and Lisbon.
Unlike the deep Glastonbury-style mud of two years ago, we had lovely weather; people sat out under the trees, discussing philosophy over a drink, or lounged on comfortable sofas listening to live music. You should have been there!
On Friday, I gave an IAI Academy course on “Secret codes”, ranging from Histaeus’s slave and the Caesar cipher, through The Mabinogion and Mary Queen of Scots, Edgar Allen Poe and Sherlock Holmes, the breaking of the Fish cipher (which brought cryptography into the electronic age), one-time pads, key exchange (with a new illustration by Neill Cameron), public-key cryptography, quantum computation, and quantum cryptography, all in two 45-minute lectures. My slides are in the usual place. There was some very good discussion afterwards, about the https protocol and how Bitcoin works, where I was a bit out of my depth, but some members of the audience were knowledgeable. No doubt the course, with an assessment, will appear on the IAI website before too long.
On Saturday I discussed randomnness with Mike Duff (my former colleague in Physics at Queen Mary, now at Imperial) and Chiara Marletto (a constructor theorist from Oxford). I sat down to dinner on Friday night, and had just ordered, when my old friend Bernard Carr and his wife Mari showed up with Chiara and Frank Wilczek; they invited me to join them, and soon Mike wandered past so we roped him in as well. Chiara and Frank had a long discussion about what constructor theory is (more on this anon), while the rest of us had a more wide-ranging conversation. I was a bit tired, having walked from Abergavenny the day before and given a course in the afternoon, so I went off to bed while most of the others went to the circus.
The debate the next day, unrehearsed despite our dinner meeting, was very enjoyable for us, and I think for the audience too. We found that we couldn’t discuss randomness without getting into some very deep philosophical waters, including time, change, free will, consciousness, and creativity. This is the sort of thing people come to the festival for!
If I understood Chiara correctly, constructor theory is a topic in quantum information theory, but aims to re-formulate the basic laws of quantum mechanics, replacing randomness by “unpredictability” (in a technical sense, that you can’t build a machine which will predict the outcome of some experiment). I may be mis-quoting, but Chiara has promised to send me some reading matter, so I may be able to give a better account later.
On the long and tedious journey home, I read a book I had bought at the Festival bookshop, Lee Smolin’s Time Reborn. I very much enjoyed his books Three Roads to Quantum Gravity and The Trouble with Physics, but I can’t say the same for this one; full of philosophical non sequiturs and unsupported assertions, so that often I wished I had him there with me so that I could argue with him! You might think this would have been the book to read before debating randomness, but in fact I was glad I hadn’t.