Dublin played host to the 17th International Conference on General Relativity and Gravitation. Up until a few days before the event only the professionals and amateur astronomers were aware of the event. What was organised well in advance were the public lectures, on the opening day of the conference, Kip Thorne, best known publicly for his book on black holes and the conference ended with a talk from Roger Penrose, probably best known for his book, `The emperors new mind.
Kips lecture predictably enough dealt with gravity, in particular gravity waves and detectors. I took two things from this talk. Firstly that in order to detect gravity waves, from for example binary black holes, we need very precise detectors, they need to detect something about 10^-16 of a centimeter. Secondly, this technology is available. LIGO the
Laser Interferometer Gravitational Wave Observatory, is the least impressive of the two main projects. The crudest explanation would be to say it is an L shaped tunnel, with each arm being 4km long, within these arms lasers are fired and if there is no `strange` gravitational interaction both beams will arrive back at the detector at the same time. If however a gravity wave happens to pass by, it will stretch one of the arms more than the other, and the slight difference in the time the lasers return will be evidence of a gravity wave, though the same result would need to be recorded in other remote locations to confirm the result. The second project is LISA This operates in a similar fashon to LIGO but is situated in space, on three satellites. This is cool because it needs to measure the distance between proof masses, separated by five million kilometers, with an accuracy of 10 picometers (10 millionths of a micron or half a billionth of an inch)!
On Friday, Roger Penrose decided to upset several members of the audience! His style, of using transparencies instead of a computer presentation, his compulsive need to wander about the stage, and his apparent clumsy organisation of the talk all led to an enjoyable lecture. He spoke about fashion, faith and fantasy in modern physics theories. Superstrings, got the label of fashionable, citing the current large numbers of papers being published as one piece of evidence. Faith, was the dubious title give to quantum mechanics, at times giving the listener that prayer was all that held it together. And inflation theory, for its impossible attempts to trace backwards through time got the fantasy label, citing brownian motion and entropy in its fairytale. It was an amusing lecture, which the crowd enjoyed, if not all of the delegates.
Oh yes and on Wednesday Morning, Stephen Hawking, turned up to admit he was wrong, and hand over an encyclopedia. No one understood his talk (Thorne and Preskill have said they didn’t understand it so god help the media who were there!). This is slightly problematic, since even those who have been arguing that he was wrong for years, didn’t expect him to prove it in this manner so now they are dubious, and those who have agreed with him up to now are equally as dubious of his achievement. It seems best to wait for the full paper to be published and digested by the experts rather than believing what some self proclaimed experts will be spouting in the coming weeks.