In memoriam Professor A. G. Gaydon F.R.S. (1911-2004)

I, a starting post-graduate in 1958, first met Dick Gaydon in the basement area of the Chemical Engineering Department of Imperial College where the nonchemical engineers were exiled. It was sometime later, when I suggested to my employers, the Central Electricity Research Laboratories, that they should produce sufficiently handsome funding for me to build and operate a shock tube. They agreed, but on condition that Dick become a consultant and keep an eye on my progress. For some years my colleagues, Bob Stirling and Sammy Sloan, and I received monthly visits.Some will have already read obituaries and additional tributes in the daily press and combustion journals. There, all have paid full regard to his outstanding contributions as one of the 20th centurys supreme spectroscopists, particularly in his accurate determination of the dissociation energy of nitrogen, with its implications for the correct forecasting of the strengths of blasts from explosions of atomic weapons. Whilst his great love in science concerned experimental spectroscopy, he devoted much effort to the development of various techniques to excite radiation. Principal amongst these were flames produced by novel types of burner and gases heated and compressed in shock tubes.Many will be familiar with his six books, some written in collaboration with colleagues such as Pearce on spectroscopy, Wolfhard on flames and Hurle on shock tubes. That on flames, together with the text by Lewis and von Elbe, formed the principal wells of information from the 1960s to the 1990s, with the former running to three completely revised editions over a couple of decades. Indubitably, the Gaydon and Hurle monograph will be most familiar to subscribers to Shock Waves. It was one of a number on shock waves published in the 1960s, e.g., Soloukhin, Bradley and Tonnies and Green. My feeling is that the Gaydon and Hurle monograph answered more experimental problems than did the others.Whilst continuing to be somewhat isolated from the chemical engineering interests of the department, he had over his career at Imperial College a wide range of physicists and chemists, both from this country and abroad, occupying post-graduate and post-doctoral positions, many of whom went on to highly distinguished scientific careers. All in all they contributed some 150 scientific papers of high merit to the most eminent of journals.Dick had many friends and collaborators worldwide. As with most of the Western World, he was highly disturbed by the USSR invasion of Hungary and, although much troubled by his conscience, gave up correspondence with long established friends amongst Russian scientists. It was some time before he rehabilitated these.He always regarded himself as an experimentalist. As the most modest of men, he would never have regarded himself as a brilliant one, though all his colleagues did. He was elected to the Royal Society, possibly in more harmonious times, in 1953. Dick was also the kindest of men. I can still recall his questioning which attempted to avoid causing hurt to presenters of contentious papers: so politely were these framed that the authors frequently remained completely unaware of the dismantling of the foundations of their case. I have often wondered how they felt when the penny eventually dropped.He had an abiding passion for butterflies and moths and travelled the world taking photographs of them. No easy task for somebody who lost the sight of one eye through an explosion of peroxide of diethyl ether, when purifying the ether itself, early in his career. When travel proved too much for him a pet dog took their place in his affections.Published online: 18 February 2005[/PUBLISHED]     

Book Review: Nonlinear Dynamics and Chaos: Where Do We Go From Here? Edited by S. J. Hogan,A. R. Champneys,B. Krauskopf,M. di Bernardo,R. E. Wilson,H. M. Osinga,and M. E. Homer. Institute of Physics Publishing,Bristol, 2002, 358 p. ISBN 0-7503-0862-1

Nonlinear Dynamics, Psychology, and Life Sciences -     

The eigenvalue spectrum of the linear Boltzmann operator in L1(R6) and L2(R6)

Summary The eigenvalue spectrum of the linear neutron transport (Boltzmann) operator has been studied in the framework of the Hejtmanek scattering approach. The spectrum turns out to be quite different from that obtained according to the classical theory; the physical aspects of this fact are briefly discussed in the last section. The two theories, however, have one aspect in common: namely that, in both cases, there exists a region of the spectral plane which is filled up by the spectrum. This is a rather disappointing fact, since it rules out, in practice, the possibility of arriving to some spectral resolution formula.

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Sommario Viene studiato lo spettro di autovalori dell'operatore integrodifferenziale lineare del trasporto dei neutroni, nell'ambito dell'approccio del tipo «teoria dello scattering» di Hejtmanek. Lo spettro risulta alquanto diverso da quello che si ottiene nell'ambito della teoria classica; un'interpretazione fisica di tale diversità è accennata nell'ultimo paragrafo. Le due teorie spettrali hanno però in comune il fatto che, in entrambi i casi, esiste una regione piana interamente occupata dallo spettro. Ciò esclude in pratica, ogni possibilità di giungere a una formula di risoluzione spettrale.

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Work performed under the auspices of the Consiglio Nazionale delle Ricerche, Gruppo Nazionale Fisica Matematica.