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book reviews The quantum jungle revisited The New World of Mr Tompkins by George Gamow & Russell Stannard Cambridge University Press: 1999. 256 pp. £14.95, $24.95 Anton Zeilinger Have you ever wondered what the twentieth century’s two great theories of physics — quantum theory and the theory of relativity — really tell us? Every physicist views these theories as providing a major break with the world-view — generally known as classical physics — that existed until the end of the nineteenth century. The problem with considering these phe- nomena, and the reason the theories were not discovered earlier, is mainly one of scale — relativity theories are concerned with the enormously high speed of light, while quan- tum mechanics is characterized by Planck’s extremely tiny quantum of action. Thus, in general, to directly ‘see’ relativistic phenome- Quantum dreaming: Mr Tompkins’ short attention span delivered him to a strange other world. na one must go to speeds far beyond the scale people are familiar with, whereas quantum rewriting some of the stories and adding new double-slit diffraction experiment using the phenomena can only be seen by analysing material. Particularly useful are his additions analogy of gazelles which, escaping from an changes occurring on extremely small scales. on cosmology, which include black holes and attacking lion through two gaps in a hedge, In 1938, the Russian-born physicist George the modern unified theory of particle physics. quantum-diffract and end up in front of Gamow, who was at that time living in the There is a beautiful explanation of the SU(3) lionesses waiting at the positions where the United States, invented the elegant idea of con- representation, which explains how elemen- interference maxima are to be expected. This sidering what phenomena we would experi- tary particles can be understood on the basis analogy, attractive though it is, is inaccurate ence if the velocity of light was not 300,000 of deeper symmetries, and how quarks are in that Stannard says the gazelles have no kilometres per second, but instead was the able to synthesize all the new particles choice other than to act as they do because speed achieved by a fast cyclist, and if Planck’s observed in high-energy physics. their dynamics is governed by quantum quantum of action was large enough for quan- Certainly the most difficult task, both in mechanics. This is incorrect, because the tum phenomena to be part of everyday experi- Gamow’s time and today, is to explain quan- gazelles merely need to approach the ‘dou- ence. Gamow invented “Mr Tompkins”, the tum mechanics to the general public. This is ble-slit’ hedge at a slightly different angle, so bank clerk who, curious about modern because its concepts are completely counterin- that their interference maxima lie between physics, attended public lectures at the local tuitive, and because even today’s physicists dis- the waiting lionesses, in order to escape. university. However, having a rather short agree about what it means philosophically. So Actually, from the point of view of modern attention span, he fell asleep during the lec- it is not surprising that Gamow’s original pre- physics, it is completely impossible to create a tures and dreamt of living in just such a strange sentation may not be totally satisfactory today. detailed visual description of what happens in world. In his dreams he rode a relativistically Stannard has rewritten a significant part of a quantum experiment between the prepara- flattened bicycle, played billiards where quan- Gamow’s original chapters on quantum tion of the system and the final observation. tum uncertainty added greatly to the excite- mechanics, but not always in a way that makes Therefore, even Gamow’s drawings showing ment of the game, and met tigers that had been them clearer. Whereas Gamow began his probability clouds or smeared-out tigers quantum-diffracted by the trees in the jungle. explanation using an analogy to billiard balls, should be taken with a substantial grain of salt. Gamow’s book was published in 1939 as without explaining clearly why the concept of Given their invalidity in principle, it might Mr Tompkins in Wonderland, with a sequel, quantum mechanics is so strange and thus have been better to retain Gamow’s original Mr Tompkins Explores the Atom, in 1944. The leaving the reader pretty much in the dark, figures and thus, through their historic two books appeared together as Mr Tomp- Stannard starts by describing how we cannot quaintness, imply that the conceptual picture kins in Paperback (Cambridge University obtain a precise measurement for the track of is outdated, rather than replace them with new Press) in 1965. an elementary particle because of the ones which still have their severe limitations. While these charming stories have been a unavoidable disturbance caused by the mea- That said, although presenting quantum source of great pleasure to many physicists, suring process. Although the discussion is mechanics accurately to a broad lay reader- some are unfortunately becoming outdated, valid, it might leave the reader believing that, ship will certainly remain a challenge for although they remain interesting historical while we cannot precisely determine, say, the some time, The New World of Mr Tompkins is documents. Given the developments of properties of an elementary particle because a lovely book which I am sure everyone physics in the second half of the twentieth cen- of the clumsiness of our equipment, the parti- interested in modern physics, from the age of tury, the physicist Russell Stannard, a popu- cle may still have well-defined properties; this 11 upwards, will enjoy enormously. ■ lar-science writer perhaps best known for his position is untenable today. Anton Zeilinger is at the Institut für Uncle Albert children’s trilogy involving the Also, in his discussion of the ‘quantum Experimentalphysik, University of Vienna, adventures of Einstein, undertook the task of jungle’, Stannard introduces the famous Boltzmanngasse 5, 1090 Vienna, Austria. © 2000 Macmillan Magazines Ltd 618 NATURE | VOL 405 | 8 JUNE 2000 | www.nature.com.

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