Professor Sir Brian Pippard

I would like to add few words to Richard Eden's excellent obituary of Brian Pippard [7 October] writes Professor Ernst Sondheimer. Eden rightly stresses the importance of Pippard's work on the Fermi surface in copper. The phenomenon used in this investigation is called the "anomalous skin effect", involving a breakdown of the venerable Ohm's law for conduction in pure metals at high frequencies and low temperatures.

In fact Pippard started to employ the microwave techniques that he had developed during the Second World War to investigate this effect on his return to Cambridge at the end of the hostilities. This allowed me to write (as co-author) the one paper which is perhaps of some lasting significance. With his deep physical insight Pippard developed a theory for the effect, called the "ineffectiveness concept", which used no mathematics (he liked to pretend, quite untruthfully, that he was no mathematician).

I was a raw research student in theoretical physics at the time and, when Pippard told me about this work, I managed to set up an integral equation for the effect, but – being not much of a mathematician myself – I couldn't solve it; for this purpose a pure mathematician had to be roped in. I then spent much of the hot summer of 1947, in the days before electronic computers, laboriously computing the results. The result was the Reuter-Sondheimer paper on the anomalous skin effect.

Brian liked to call me, with good reason, a "formalist". He was a role model for me, and a good friend.

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