When reading books, I have a habit of folding over the top of the pages when there is something that catches my eye. It might be a nice turn of phrase, an amusing anecdote or an interesting fact. The only trouble is that I never go back to the folded pages and if it is a library book, I imagine that the next reader finds it very irritating. I recently read the
award winning biography of Paul Dirac,
‘The strangest Man’ by
Graham Farmelo. As a physics teacher with an interest in the history of science, I read quite a lot of scientific biographies and this one completely captivated me in a way that no scientific biography has done for a long time. It is brilliantly well written, interesting and sheds light on a physicist who should be better known in his native country. He won the Nobel prize alongside Schrodinger and Heisenberg both of whom are far more famous in Britain.
I really do recommend it and the
wonderful reviews only serve to emphaise just how good it is. It was so good, that I decided to keep a record the folded pages from the book so that I can refer back to them to add colour to lessons on quantum physics. Page numbers refer to the hardback edition published in 2009.
P99 –
Schrodinger first discovered his quantum theory of the atom in the Christmas holidays of 1925 whilst on an illicit skiing weekend in Switzerland with his girlfriend; very raffish.
Page 100-101 - Most people find it easier to understand a theory if they can visualise it in some way. This was the great attraction for many physicists of Schrodinger’s quantum theory of the atom (a generalization of
de Broglie’s idea that all particles have a wave associated with them). We can ‘see’ waves and the maths of waves was well known, wheras Heisenberg’s earlier approach to the same problem used the abstract mathematical tool of matrices. Both approaches were later shown to be identical but the clash between those who wanted to visualise the atom and those who saw this as unnecessary and even unhelpful has continued ever since. Dirac was very much on the abstract mathematical side.
P103 – A lovely analogy to illustrate the difference between photons (which are
bosons with integer spin) and electrons (which are
fermions with half integer spin). Only 2 electrons are allowed in any given energy level (one with spin +1/2 and one with spin -1/2). On the other hand, there is no limit to the number of photons that can occupy a given energy level. The analogy relates to a bookcase. An electron bookcase would only allow 2 books per shelf whereas a photon bookshelf would allow any number of books. “It is as if electrons are unsociable whereas photons are gregarious”. I can even see this analogy extending to people. Are you an electron or a photon?
P121 – A famous Dirac story told by Robert Oppenheimer about Dirac and poetry. Dirac did not share Oppenheimer’s interest in literature and especially poetry. “I don’t see how you can work on physics and write poetry at the same time. In science you want to say something nobody knew before, in words everyone can understand. In poetry, you are bound to say something everybody knows already in words that nobody can understand”.
P142 The ‘achingly beautiful’
Dirac equation which brought together quantum mechanics and special relativity to describe the electron.. It is carved into his
memorial stone in Westminster Abbey.P171 – A nice nod to the literary. In ‘
Gulliver’s Travels’ , Jonathan Swift writes on the basis that nobody would notice the difference if all objects got bigger or smaller in equal proportions. For smaller things, as Dirac pointed out, this is simply not true. The world of the atom obeys strange laws that do not scale up to the macroscopic world in which we live. To paraphrase
L P Hartley, 'the atom is a foreign country, they do things differently there'.
P176 – The word
scientist was coined by William Whewell in 1934 and adopted by the British Association for the Advancement of Science. It was far from universally liked and alternatives considered were ‘savants’, ‘nature peepers’ and ‘nature pokers’. I like the idea of a GCSE in Nature Peeping.
P195 –
Wolfgang Pauli’s wife had the impertinence to leave him for a mediocre scientist. ‘Such an average chemist’. Dirac co-presented a seminar with Pauli at Princeton at which he stated quite clearly his belief that the anti-electrons his theory predicted should be detectable and that they were not simply mathematical abstractions.
P232 – The splitting of the atom by
Cockcroft and Walton was the first experimental proof of probably the most famous equation of all time; E=mc
2. As it was first published in 1905 by Einstein, I had no idea that it was not proven to be true before this.
P212 – Anderson publishes the
first photograph of an anti-electron in a cloud chamber photograph. The article was titled ‘The Apparent Existence of Easily Deflectable Positives’. Nobody realized the significance of the paper for some time.
P224 – The name positron is coined. Anderson and his colleagues suggested that the electron be rechristened the negatron. What a pity that it wasn’t; such a sci-fi sounding name.
P226 – A
Kurt Gottfried quote; ‘Physics has produced other far-fetched predictions that have subsequently been confirmed by experiment. But Dirac’s prediction of anti-matter stands alone in being solely by faith in pure theory, without any hint from data, and yet revealing a deep and universal property of nature’.
P379 –
Fred Hoyle commenting upon the
Big Bang theory. As a leading proponent of the alternative
Steady State theory, he found the idea of a Big Bang distasteful and compared the idea of the universe emerging out of nothing to a ‘party girl’ jumping out of a cake; ‘it just wasn’t dignified or elegant’.
The Oxfordshire branch of the 
The brain child of British physicist Sir Tim Berners-Lee, the World Wide Web is 20 years old today. 