Relativity Revisited the Chronological Series of Letters

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to the main events and ideas in the corre- themselves constitute one of the most vivid spondence;without it,it would be difficult to and valuable testimonies to the development keep in mind the main themes when reading of modern science. They also tell us much Relativity revisited the chronological series of letters. There is about the personal hardships that Einstein The Meaning of Relativity (5th edn) also an explanation of the editors’ triage of and Born overcame during two world wars, by Albert Einstein, with an introduction by the voluminous correspondence: some let- the vagaries of academic life, the daily grind Brian Greene ters are known but are inaccessible now, and of administrative work, the steadfastness Princeton University Press: 2004. 192 pp. the editors relegated other, less significant, and frailty of human relationships.” $14.95, £9.95 letters to reference in a calendar at the end Perhaps the most famous of these letters Special Relativity: A First of the volume. And although the corres- deal with the fundamental difference Encounter pondence is presented only in the original between these two good friends, with Born by Domenico Giulini language, mostly German, happily there upholding what came to be the Copenhagen Oxford University Press: 2005. 160 pp. exists a separately published English trans- interpretation of quantum mechanics, £14.99, $24.95 lation, provided by Ann and Klaus according to which the foundations Einstein 1905: The Standard Hentschel (Princeton Univer- of physics are laws of statistical of Greatness sity Press,2005). nature.Einstein responded in by John S. Rigden Many of the most inti- 1926: “Quantum mechan- Harvard University Press: 2005. 192 pp. mate letters in volume 9 ics is certainly imposing. $21.95, £14.95 are exchanges between But an inner voice tells Werner Israel Einstein and Max Born me that it is not yet the and his wife Hedwig. real thing. The theory What, another three books on Einstein? At Here,Einstein can says a lot. But it does the last count on www.amazon.com there truly relax and share not really bring us any were 498 currently in print, and the prolif- the good and the sad closer to the secrets eration of titles such as The Private Albert AIP EMILIO SEGRE VIS.AIP EMILIO SEGRE STEIN ARCH./MARIA in his life, his scien- of the ‘old one’. I, at Einstein, Einstein in Love and Einstein’s tific, social, musical any rate, am convinced Daughter should ensure that no corner of and personal thoughts. that He is not playing his life is left untouched. Max Born, whose Nobel at dice.” As a refreshing change, The Meaning of prize for his work in This judgement, Born Relativity,Special Relativityand Einstein 1905 quantum mechanics was records, was for him “a hard deal exclusively with science. All three are delayed until 1954, contri- blow”, separating Einstein valuable additions to the Einstein canon. buted to a wide spectrum of from the younger physicists The Meaning of Relativity, the master’s own fields, including relativity, In touch: Max Born and his wife of which Born, though only presentation based on lectures given at optics, crystal physics, epis- regularly wrote to Einstein. a few years younger than Princeton University in 1921, reappears in a temology, the theory of Einstein, considered him- reprinting of the final (1953) edition, which liquids and arms control. Max and Hedwig, self part. But the friendship survived, not included as an appendix his parting thoughts who was a delightful companion and corre- least by the intervention of Wolfgang Pauli, on his last abortive bid to unify the gravita- spondent, left Germany for Edinburgh after who cleared up a misunderstanding between tional and electromagnetic forces. This was Max was driven out from Göttingen in 1933. Born and Einstein. The exchange of letters in fact a revival, with modifications, of his His son,Gustav,tells that his father had taken continued, testifying to their constant inter- earliest attempt, begun in 1925 but soon seriously Einstein’s advice to leave immedi- ests in developments ranging from atomic abandoned because, as he admitted in 1927: ately,“thus helping to save the family”. physics to cosmic rays, from quantum “As a result of numerous failures,I have come The 117 surviving letters between the mechanics to stellar spectra, and of course to the conclusion that this road does not lead Borns and Einstein from 1916 to 1955 were relativity (the new ‘ether drift’ experiments, us closer to the truth.”It is curious that none published as a book in German in 1969,with gravitational red shift, gravitational light of his later works mentions this early attempt. an introduction by Werner Heisenberg, at deflection and gravitational waves). Not too much should be made of this; Ein- one time Born’s assistant. It had a foreword But we hear also about the pair’s inter- stein was always sparing with references (this by Bertrand Russell,who succinctly summa- vention in humanitarian causes, the turmoil entire book has just one).Yet one cannot help rized what that book showed in its essence: in politics throughout Europe after the First wondering: could it have slipped his mind “In an age of mediocrity and moral pygmies, World War, programmes to help refugee that he had been down this path before? their lives shine with an intense beauty. scientists, and the devastating events of the Brian Greene’s easy-to-read 24-page intro- Something of this is reflected in their corre- Second World War. The new preface also duction touches on several developments spondence, and the world is richer for its contains valuable brief accounts of the way since Einstein’s time. One of these is super- publication.” For most of the letters, Max that physics, after the death of these two string theory, which carries forward Ein- Born provided perceptive editorial com- great minds, continued along lines they had stein’s quest for unification. Another is the ments, explaining the circumstances of the pursued,showing in some detail how experi- recent discovery that the cosmic expansion time in which the letters were written. mental and theoretical work in the past few is accelerating, with its strong implication An English translation of the book decades has confirmed with great precision that Einstein’s self-styled “greatest blunder” appeared in 1971, but has been long out of some of their daring speculations. — the cosmological constant — was perhaps print. The new English-language edition of In short, these two related volumes act not such a dumb idea after all. The Born–Einstein Letters 1916–1955 — as a kind of microscope through which to Giulini’s book Special Relativity has a issued by Nature’s publisher Macmillan as view a turbulent period in the twentieth narrower focus, concentrating exclusively part of its new science imprint — is essen- century. ■ on Einstein’s special theory of relativity. It is tially unchanged from the earlier version, Gerald Holton is Mallinckrodt research professor particularly strong on experimental tests but greatly benefits from an extensive preface of physics and research professor of the history and ramifications of the theory, and on the by Buchwald and the physicist Kip Thorne. of science, Department of Physics, Harvard evolution of relativistic ideas, from Galileo To quote from the preface: “The letters University, Cambridge, Massachusetts 02138, USA. and Newton,through the nineteenth-century

Science in culture The great portrait mystery

A disputed portrait of Robert Hooke may in fact show a contemporary.

Philip Ball ON

At the tricentenary of Robert Hooke’s death two years ago, no one knew what he looked like. Despite Hooke’s reputation as one of the principal architects of the scientific revolution, there were no known surviving portraits of him — an outcome, it was rumoured, of his enmity with Isaac Newton, who did all he could to erase Hooke’s image after TURAL HISTORY MUSEUM,TURAL HISTORY LOND

his death. NA But in 2003, historian Lisa Jardine ruffled academic feathers by boldly claiming to have discov- ered a portrait of Hooke, which featured on the cover of her biography The Curious Life of Robert Hooke (HarperCollins, 2003). This painting has resided for more than a century in the Natural History Museum in London, where it was taken to be a portrait of the British naturalist John Ray (1627–1705) painted by the seventeenth- century artist Mary Beale. The painting was bequeathed as such to the museum in 1787 after the death of its former owner, the botanist William Watson. Jardine argued that the visage looks nothing like other portraits of Ray, and that the features instead match some contemporary descriptions of Hooke, who was said to have Getting the brush-off: the above painting, thought to be of Robert Hooke, bulging grey eyes and curly may have been based on an engraving of Jan Baptista van Helmont. brown hair and to be of emaci- ated appearance. Others have Ortus medicinae, pub- Helmont died, so there seems to be no possibility found this evidence not only lished posthumously by of the reverse confusion. slender but also unconvincing: the his son Franciscus Mer- So where did the ‘Ray’ painting come from? face is certainly unusual, but does it curius van Helmont (whose Jensen says that Franciscus van Helmont had his really correspond in any regard to these likeness is inserted behind his own portrait made while he resided in England accounts? father’s on the same page). Van Hel- during the 1670s, and might have commissioned Now William Jensen, a specialist in the history mont’s writings were never published in his lifetime a picture of his father at the same time, based on of chemistry at the University of Cincinnati, has an because he was persecuted as a heretic by the the earlier engraving. But then who was the artist? alternative proposal. He points out in Ambix (51, Spanish Inquisition and forced to live under house And why did Watson, a hundred years later, have 263; 2004) that the portrait can be superimposed arrest in Vilvoorde, near Brussels, until his death. the false impression that he owned a painting of remarkably well onto an engraving of another Particularly telling is the wispy moustache and Ray by Mary Beale? influential seventeenth-century scientist, the underlip hair in the 1648 work, which is reproduced The haunting image clearly still holds myster- Flemish chemist and physician Jan Baptista van in the portrait thought to be of Ray. There ies. But the face of poor Robert Hooke may have Helmont (1579–1644). The engraving appears in is no record of Hooke having sported such facial vanished once more from history. the 1648 edition of van Helmont’s great work hair. Hooke was only nine years old when van Philip Ball is a consultant editor for Nature. aether theorists, and up to A. A. Michelson, volumes are not heavy (Giulini uses nothing today is none of the above (they are scarcely Edward Morley, George FitzGerald and beyond high-school algebra), but they do cited at all), but his PhD thesis on the deter- Hendrik Lorentz. require close attention from the reader. In a mination of molecular dimensions. This is Have Lorentz and Henri Poincaré lighter vein is John Rigden’s enjoyable con- because the methods he used for it have been received less than their due in this great con- tribution, Einstein 1905.This is a month-by- widely applied to such problems as the ceptual revolution? I think Giulini puts the month chronicle of 1905, Einstein’s annus motion of sand particles in cement mixes case fairly: “In retrospect, special relativity mirabilis,in which appeared in quick succes- and of aerosol particles in clouds. As Rigden seems palpably close in 1905,after all the pre- sion his four epoch-making papers on the remarks:“When a paper is so important that liminary works of Voigt, Hertz, FitzGerald, photon hypothesis, brownian motion, spe- it could be cited in almost every paper, it is Lorentz, Larmor and Poincaré. But appar- cial relativity and Eǃmc 2.Rigden explains cited in almost no paper”. ently it needed an unprejudiced newcomer the underlying ideas in clear, elegant, non- Werner Israel is in the Department of Physics, to take the final step.” mathematical prose. Amusingly, of all of University of Victoria, Victoria, British Columbia, The mathematical demands of these two Einstein’s 1905 works, the one most cited V8W 3P6, Canada.