Archive for April 10, 2012

Dyson on Eddington

Posted in Books, Talks and Reviews, The Universe and Stuff with tags , , , , , , on April 10, 2012 by telescoper

I’m grateful to George Ellis for sending me a link to a book review written by Freeman Dyson that appeared in a recent  edition of the New York Review of Books. I was particularly interested to read the following excerpt about Arthur Stanley Eddington. I have been intrigued by Eddington since I wrote a book about his famous expeditions (to Principe and Sobral) in 1919 to measure the bending of light by the Sun as a test of Einstein’s general theory of relativity; I blogged about this on its ninetieth anniversary, by the way, in case anyone wants to read any more about it.

Although I read quite a lot about Eddington, not only during the course of researching the book but also afterwards, as there are many things about his character that fascinate me. He died long before I was born, of course, but whenever I meet someone who knew him I ask what they make of him. Not altogether surprisingly, opinions differ rather widely from one person to another as his character seems to have been extremely contradictory. He doesn’t seem to have been very good at small talk, but was nevertheless a much sought-after dining companion. He was a man of great moral integrity, but at times treated his colleagues (notably Chandrasekhar) rather shamefully. He was a brilliant astrophysicist, but got himself hooked on his peculiar Fundamental Theory which was a dead end. He remains an enigma.

Anyway, this is what Dyson has to say about him:

Eddington was a great astronomer, one of the last of the giants who were equally gifted as observers and as theorists. His great moment as an observer came in 1919 when he led the British expedition to the island of Principe off the coast of West Africa to measure the deflection of starlight passing close to the sun during a total eclipse. The purpose of the measurement was to test Einstein’s theory of General Relativity. The measurement showed clearly that Einstein was right and Newton wrong. Einstein and Eddington both became immediately famous. One year later, Eddington published a book, Space, Time and Gravitation, that explained Einstein’s ideas to English-speaking readers. It begins with a quote from Milton’s Paradise Lost:

Perhaps to move
His laughter at their quaint opinions wide
Hereafter, when they come to model heaven
And calculate the stars: how they will wield
The mighty frame: how build, unbuild, contrive
To save appearances.

Milton had visited Galileo at his home in Florence when Galileo was under house arrest. Milton wrote poetry in Italian as well as English. He spoke Galileo’s language, and used Galileo as an example in his campaign for freedom of the press in England. Milton had witnessed with Galileo the birth struggle of classical physics, as Eddington witnessed with Einstein the birth struggle of relativity three hundred years later. Eddington’s book puts relativity into its proper setting as an episode in the history of Western thought. The book is marvelously clear and readable, and is probably responsible for the fact that Einstein was better understood and more admired in Britain and America than in Germany.

As a student at Cambridge University I listened to Eddington’s lectures on General Relativity. They were as brilliant as his books. He divided his exposition into two parts, and warned the students scrupulously when he switched from one part to the other. The first part was the orthodox mathematical theory invented by Einstein and verified by Eddington’s observations. The second part was a strange concoction that he called “Fundamental Theory,” attempting to explain all the mysteries of particle physics and cosmology with a new set of ideas. “Fundamental Theory” was a mixture of mathematical and verbal arguments. The consequences of the theory were guessed rather than calculated. The theory had no firm basis either in physics or mathematics.

Eddington said plainly, whenever he burst into his fundamental theory with a wild rampage of speculations, “This is not generally accepted and you don’t have to believe it.” I was unable to decide who were more to be pitied, the bewildered students who were worried about passing the next exam or the elderly speaker who knew that he was a voice crying in the wilderness. Two facts were clear. First, Eddington was talking nonsense. Second, in spite of the nonsense, he was still a great man. For the small class of students, it was a privilege to come faithfully to his lectures and to share his pain. Two years later he was dead.


The World as a Beach

Posted in Biographical, The Universe and Stuff with tags , , , , , , on April 10, 2012 by telescoper

Well, as some of you will have noticed, I’ve been offline over the long weekend. There’s no internet connection – not one that I could get to work, anyway – at the residence I’m staying in and I couldn’t be bothered to traipse all the way up the hill to the department in the pouring rain to connect from my office. Hence the first gap in my postings this year. I don’t suppose anyone minds that much. Anyway, here are a few pictures and random thoughts from the weekend.

Here’s a picture of the residence, by the way. It’s called Kopano, although when I previously stayed it was called Driekoppen. The old name was a relic of the days of slavery – three slaves were tortured and executedin public  after rebelling against the terrible conditions they were held in. Their heads were displayed on pikes nearby, hence the name which means “Three Heads”. This was in 1724. I’m not surprised that the end of apartheid brought a change in the name, although keeping it as it was would have served as a reminder of South Africa’s terrible past. One shouldn’t  become obsessed by events that took place such a long time ago, but neither should one forget them.

Good Friday was a very Good Friday indeed, starting with a lovely breakfast and a walk on the beach in Muizenberg. Apparently this is something of a surfer’s paradise but, as I said, I didn’t have an internet connection so couldn’t join in. Also, they have sharks here. I mean big ones. Great White ones, as  a matter of fact. None showed up while I was there, though, and in any case I was only paddling along the shoreline. It may not be obvious from the picture, but it was pretty hot. Almost 30 degrees.

 I was watching a chap surfing while we walked along and it reminded me of the post I did a while ago about teaching analogies. Standing on a beach looking out towards the horizon is a bit like doing cosmology. Off in the far distance everything looks smooth; the waves on the surface are much lower in amplitude than the depth of the sea out there, so everything evolves linearly and is quite easy to understand. That’s like looking back in time at the early Universe imprinted on the cosmic microwave background. Nearer to the shore, however, the waves become non-linear because their height is comparable to, or larger than, the depth of the water. These waves evolve in a non-linear way producing, breaking on the beach to produce foam and spray, just as the primordial waves collapse to form galaxies and the foam of large-scale structure when their self-gravity becomes sufficiently strong.

That’s enough of that, I think.

Unfortunately, the weather changed for the worse over the rest of the Easter weekend and torrential rain kept me from doing much on Saturday or Sunday. The finishing section of the  Two Oceans Marathon, which ended on the UCT campus on Saturday, was like a quagmire. As you can see from the picture, I reached the line well in front of the pack. About two days in front, actually. I took this as they were building the stands and hospitality tents a few days before the race.

Anyway, the good side of the bad weather was that I got quite a lot of work done, catching up on things I have let slip for far too long. I also exhausted the reading material I brough with me, so will have to find a good bookshop in the next day or two. Well, that’s about enough for now. I hope to continue regular dispatches from now on until I return to Blighty  next week.