"The Strangest Man"
the hidden life of Paul Dirac, quantum genius,
by Graham Farmelo,
published by Faber and Faber, 22 Jan 2009,
ISBN: 0571222781 
http://www.amazon.co.uk/Strangest-Man-Hidden-Quantum-Genius/dp/0571222781/

I found this biography of Dirac to be a wonderfully good read.

Heretofore, it might have been thought that Dirac would 
offer sparse material to a biographer. He was, after all, 
someone who spoke little, showed emotion rarely, and spent 
the last 50 years of his scientific career failing to 
improve upon what he so signally achieved in the 10 years 
from 1922 to 1932.

But Graham Farmelo has squared this circle and shown, to me 
at least, that Dirac led a multi-faceted life, within limits 
of human reserve and poor nurturing that might have blighted 
a lesser spirit.

And this book has such a fine pacing to it!

In the account of Dirac's early school days, I was waiting 
for signs of extraordinary ability to appear, yet what I 
retained was a sense of serious effort by an assiduous 
trier.

Then, when recognition of his talents was forthcoming, it 
seemed clear that this young man was set to be a meticulous 
engineer, with a passion for reading about relativity in his 
spare time.

Next, on to Cambridge, more by good luck than good 
judgement, where he was picked out as a "bright man", but 
received from that university little nurture, then, or 
perhaps (if I decode Farmelo aright) thereafter.

And then the most wonderful thing happens: as a reserved 
post-doctoral researcher, Dirac sets the wave mechanics of 
Schroedinger next to the matrix mechanics of Heisenberg 
(supplemented by Born and Jordan) and in a few months turns 
one of the strangest stewing pots in the history of science 
into a lucid and almost austere synthesis, whereof one can 
only say: "Es muss sein!" 

Students of physics, like me, still get a strange frisson 
from the first 6 chapters of Dirac's book. "My book", he 
said, daring to use the possessive pronoun. How could he be 
so sure, so early? How does a mind working on muddle make 
such a monument, alone?

Then the oft-told story, that still leaves one in awe, of 
wrestling to make quantum theory consistent with special 
relativity and succeeding only at the price of 
hypothetically enlarging the world from one made exclusively 
of electrons and protons, with nature soon asserting that it 
is indeed richer, revealing positrons bending the "wrong" 
way in a magnetic field. (For those interested in more 
details, I recommend Norwood Hanson's book "The Concept of 
the Positron" (1963), which is oddly missing from Farmelo's 
otherwise impressive bibliography.)

But hang on a moment! We are now only up to page 234, with 
200 pages of text and 50 years of Dirac's life to go, and 
the glories of Dirac's (yes, Dirac's) quantum field theory 
(QFT) still to explore. Yet the author tells us that Dirac 
has already become marginal to QFT and after his Solvay talk 
of 1933 will never again use it "to probe the inner workings 
of the atom."

"Oh dear, how sad, it's going to be a grim read from here on in" 
one might be tempted to think. Far from it!

This, for me, is where the book blossoms into a quietly (and 
to me profoundly) moving biography of a man who went on to 
share 47 years of married life with "Wigner's sister"; who 
raced his children to the front door for the "Beano" and 
watched soap operas on TV, yet rarely smiled; whose papers 
of 1950 and 1958 are referenced in Steven Weinberg's 
scholarly account of the "canonical formalism" of QFT; who 
made a "bag model" long before MIT had the same idea; who 
declined to attend a big conference on the 50th anniversary 
of his idea of a magnetic monopole, on the grounds that 
there was no experimental evidence for any such thing, 
preferring to go to a conference looking for changes in the 
Earth's crust that might signal a change in time of a 
fundamental "constant"; who told me, in 1981, with light in 
his eyes, how Schroedinger, Born and he had plotted (and of 
course failed) to "calculate the value of the fine structure 
constant", during the second world war. (A story later 
confirmed for me by Father James McConnell of the Dublin 
Institute for Advanced Studies.)

I think that the deep reason why Farmelo was able to marshal 
such an absorbing story of Dirac's "concluding" 50 years is 
that the man changed little. Moreover, that little was 
largely for the better. We ought not to be judged for our 
impact, but rather for our intent. Dirac kept to his 
constant intent of trying to understand nature in terms of 
the simplest and most beautiful ideas he could attain. From 
that intent had come his greatest impact. We should not 
cavil that the same intent bore less fruit, later, for that 
would be to deny its authenticity, earlier.

Farmelo suggests that Dirac may have cried only once: on 
hearing of the death of Einstein, who was not a close 
personal friend. At page 413 of this simply wonderful 
biography, my own eyes turned moist.

David Broadhurst, 3 April 2009