Friday, 26 February 2010

The Magic of Richard Feynman

Feynman DiagramsRichard Feynman (1918-1988) was one of the more colourful and charismatic characters in US physics.
He's remembered as one of the greatest physics minds of the Twentieth Century, which sometimes leaves non-physicists wondering exactly what it was (apart from Feynman diagrams) that he actually did to get that reputation. How did he end up being regarded as some sort of god amongst physicists, he never actually discovered anything that most people will have heard of?

One of Feynman's hobbies was stage magic. He was a keen practical joker, and was fascinated by the way that people are led to believe certain things, or why they end up acting in certain predictable ways. He was fascinated by fallibility, and predictable fallibility, which is one of the reasons why he was such a a great choice when they were picking people for the Rogers Commission, to investigate the reasons for the 1986 "Challenger" space shuttle disaster. Feynman understood the concept of system failure, both at the organisational and personal level, and he liked to play with people, including other physicists.

Stage magic often works through a process of misdirection. The practitioner demands with every element of their voice, facial gestures and body language that the audience may like to look over //here//, to the extent that we find it almost impossible not to look at their selected spot – perhaps an inch or so away from their extended, waggling fingertips – while with their other hand over //there//, they perform the mechanics of the actual trick.

A magician might announce before performing their stunt: "Look at this table. It's a perfectly ordinary table. It really, really is." And they bang on the table with their fist, and walk around it, and hit it with a stick, and mark an X on it with white chalk ... and you're concentrating so hard on the table to try to find why it's NOT an ordinary table, that you fail to notice the large black velvety cloth hanging above it, or the trap door behind it. The table is, in fact, completely ordinary. It's a double-bluff.

That's misdirection. You don't necessarily tell the audience something that's untrue or misleading, you give them a series of false clues, and let them work out the wrong story for themselves.

Another factor that makes stage magic effective is the way that people apply Occam's Razor. Technical stage tricks often require ludicrous amounts of preparation, absurd amounts of technical expertise or physical dexterity, and improbable investments in custom hardware. The assistant just happens to be double-jointed, or has an identical twin sister, or a false leg. At some subconscious level, the watcher's mind runs through a set of absurdly complicated and tortuous conspiracy theories that might explain what they're seeing and gives up, deciding that it's simpler to assume that the magician really can fly or make tigers disappear. The audience reasons that this isn't true (it's "only a trick"), but at a gut level they've already suspended disbelief enough to enjoy the show.

And so, to Feynman's magic trick.
One of the recurring stories about Richard Feynman goes something like this:
A physicist is working on a difficult problem. The physicist contacts Feynman. Feynman's secretary replies that Feynman is very busy, but could maybe schedule a meeting at some nebulous future date.
Several months pass. The physicist is contacted unexpectedly by the secretary to say that the secretary has just spotted that Mr Feynman now has a gap in his schedule, at quite short notice, and would the physicist still like to make use of it? The physicist eagerly agrees.

The physicist walks into Feynman's office.
"So,", says Feynman, "My secretary's just told me that you're working on some sort of interesting problem, but you'll have to forgive me, I've been really busy for the last couple of days, and haven't had the chance to look into it. Could you explain it to me? Oh, and could you start from scratch and make it simple, because, you know, this really isn't my field, and I'm not really up to speed with this subject. Start from the beginning."

The visitor is flattered and walks up to the board and starts explaining the nature of the problem. He pauses.

"So", says Feynman, "Let me see if I've got this right ..."

Feynman stares at the board and frantically marks symbols up while talking through what he's doing, until he has an equation.

"So your starting point would be something like that, yes? Okay, now tell me what you did next."

The visiting physicist is dumbfounded. What Feynman has just written on the board is the solution. And it's not just the solution, it's the solution to a more general version of the problem than the one that the visitor has been struggling with for months, or years. And Feynman's just done it in about three minutes flat.

The physicist leaves, ego totally destroyed, knowing that RF is in a totally different league to lesser mortals like himself.

Now, the "reveal".

If you were a suspicious stage-magician type, what you might suspect happened would be something like this: Physicist contacts RF's secretary, mentioning something about the problem. Secretary tells Feynman. RF researches the problem and all the relevant papers on the subject, and finds out how far the physicist has gotten. The secretary sends a stalling letter. Feynman adds the problem to his stack of other outstanding problems, playing them off each other, trying to cross-fertilise the different issues and bounce ideas between them, considering it a break from the problems he's actually trying to work on for himself. Finally, he works out the solution, and at this point, his secretary sends out the letter saying that RF now has an unexpected gap in his schedule.

Physicist arrives, RF plays dumb and asks them to outline the problem, RF "solves" it in three minutes flat, apparently using only the tools that the visitor has just provided.

Of course, this scenario still required RF to have been a damned good theoretical physicist. It also required RF to have had a wicked sense of humour, and to have done an awful lot of tough background work each time he pulled his stunt, just to create a few brief minutes of surprise for his "audience".

But that's exactly what stage magicians do.

Wednesday, 24 February 2010

"Relativity in Curved Spacetime", PDF eBook

'Relativity in Curved Spacetime', PDF ebook version, screenshotI've just provisionally put Relativity in Curved Spacetime online as an eBook, to see what happens. It's the full fixed-layout PDF file for the book, with an added "bookmark pane" PDF index and some annotations. If you're curious about the page layouts or you'd like a single-sheet PDF listing of the book's contents, click on the links.

I've initially priced the thing at USD $4-99, which comes out as about three quid in British Pounds. That's about a third of what Apple are going to be charging for ebooks.

If you want a nicely-bound hardcopy, and don't fancy printing off nearly 400 sides of paper, you can still buy the paperback and hardback. Otherwise, the PDF version's on .