book reviews

“Tesla unveiled the first radio tube in this sec- before, but this book presents a more system- putting it better. Others have gone for a cup ond month of 1892”. This is followed by a atic development. of tea.” description of electrical discharges in a vacu- His four strands are quantum theory, the How can one understand these ideas? um and a quotation with a footnote. But the theory of computation, the theory of evolu- When an electron goes through two slits (in source cited does not refer to the material in tion and the theory of knowledge. He con- the double-slit experiment) there results a this paragraph, nor is the quotation there. cludes that scientists have not taken their superposition of states, and one might talk I wish I could have written a positive own theories sufficiently seriously; they are about a plurality of potential electron states. review. In this 542-page work there is a good instead “clinging irrationally to what could The next step is to associate possible worlds 200-page book struggling to get out. All the be called ‘paradigms’”. For example, optical in which these states are realized individ- requisite material is there. What is needed is a interference experiments involve photons ually. This is done here. But it will come as no ruthless editor and the two professional and we can detect, and others whose presence we surprise that there is resistance to the phrase critical readers that most academic publishers infer merely from their interference effects “many worlds”, for it can conjure up “onto- require. on the observable photons (“tangible” and logical profligacy gone mad”. L. Pearce Williams is at 207 Iradell Road, Ithaca, “shadow” photons respectively). Take this Another terminological point, not made New York 14850, USA. seriously, Deutsch advises, and call the tangi- by the author, is elementary but important. ble particles our universe and each shadow When physicists talk about “the universe” particle a part of a parallel universe. that occurs in their theories, they always House of cards This raises a terminological point. mean some model universe, not the actual Deutsch drops the term “universe” as a universe we observe, to which the model is, The Fabric of Reality description of the whole of physical reality, at best, a good approximation. by David Deutsch because what we see and study would then be A reader may well want to hurry on to Allen Lane: 1997. Pp. 390. £25. To be merely a portion of it, and so would require a quantum computers, which are associated published in the United States on 1 August new name. He uses “universe” to denote only with some seminal papers by Deutsch. at $29.95 the part of physical reality that we normally Indeed, here we find a reference to Peter Peter T. Landsberg study. And the rest — the physical reality as a Shor’s algorithm — a way of factorizing whole? Well, just call that a “multiverse”, and numbers of the order of 1 followed by 500 The great outpouring of ‘popular science’ we have got our nomenclature. There seems zeros. These are huge numbers, if we recall books continues unabated. Often they deal to be no difference between the multiverse that the number of particles in the observ- with modern physics and provide an intro- and the notion of parallel universes. able universe is estimated to be ‘only’ 1 fol- duction to recent progress. Sometimes they Things analogous to each other are sup- lowed by 80 zeros. The factorization, asserts suggest a new philosophy or world view. This posed to happen in the parallel universes. In Deutsch, uses the resources of the parallel book is in the second category. Knowledge- one of his few lighter touches, Deutsch universes. His challenge is: “Explain the able, fiercely outspoken and quite partisan, speaks of variants of himself in these parallel algorithm on a single-universe world view.” I David Deutsch aims to introduce us to his universes: “Many of those Davids are at the hope that computer scientists can and will view of reality. He has written about this moment writing these very words. Some are take up this challenge. Here, as in other places, I was disap- pointed that the author could not give a briefer and more incisive introduction to basic ideas. Must one really still also go to articles in Scienceor Physics Worldto find out about quantum computers when one has this book? I have a feeling that Deutsch is so keen to propagate his ideas that he some- times neglects a more straightforward expo- sition. He does not warn us, for example, that there could be obstacles to the construc- tion of quantum computers that may not be overcome for many years. The main difficul- ties will arise from the nature of the error correction needed and from quantum mechanical decoherence problems. There is some fun to be had in the chapter on time travel. The most interesting type is travel into the past, and there is still some doubt whether this is ‘allowed’ by our scien- tific laws. If it is, one may expect messages from the future. But visitors from the future “cannot know our future any more than we can, for they did not come from there”. Deutsch engages us in various speculations, . . . nor any drop to drink some of which, as he admits, would not be Floods come quickly upon villagers in the Ganges water-shy snakes. From Delta: The Perils, Profits out of place in science fiction. and Brahmaputra delta, particularly when dams and Politics of Water in South and Southeast Asia, To whet appetites, here are some memo- on the other side of Bangladesh’s land borders are a photographic survey by Daniel Schwartz of life rable quotations: “While most mathemati- opened without warning. People seek refuge on in these impoverished yet resourceful delta cians and computer scientists take the cer- roofs, only to be at risk from deadly bites of regions. Thames and Hudson, £28. tainty of mathematical intuition for granted, they do not take seriously the problem of

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In retrospect chosen by Euan Nisbet

Emma Society and the fight against slavery. After the volcano in what is now Indonesia. In the cool by Jane Austen devastation of the Napoleonic wars, Howard and spring of 1996, mild in comparison to 1814, (1816) his friends in the United Kingdom and United apple trees flowered as late as early June. The Climate States collected a vast sum, equal to many Perhaps Austen herself saw apple blossom on of London millions today — and took it to help the two hot days, 14 June (85 °F) and 15 June (78 °F), by Luke Howard distressed people of Germany. Even Goethe, who at Painshill and Box Hill. Then the weather (1833) wrote In Honour of Howard, addressed him as broke. On 21–23 June, Howard notes that a “fire ‘master’. in the grate has been again acceptable”, an On the warm evening of 22 July 1813, observation worthy of Mr Woodhouse himself. Howard records his visit to Alton, Hampshire. As Only as June ended did summer reappear. In July Austen: acute he travelled through Chawton, just before Alton, came clouds of uncommon beauty. In Emma “it observer of he would have passed before Austen’s dining cleared; the wind changed into a softer quarter; the weather room window, the outlook of one who was his the clouds were carried off, the sun appeared; it equal in meticulous observation. Whether they was summer again”. Did Mr Knightley come to Why choose Emma? Emma is weather. met that day we do not know but it seems call on Wednesday 6 July 1814? Meteorology shapes the novel. This is a work of possible. Howard was a campaigning celebrity Is it presumptuous to attempt to match the science, seamlessly woven into art. Emma is with links to the Lloyd and Barclay families, weather to the novel? Possibly — an author has perfect. The slightest change would disrupt the Quaker bankers. There were Barclays in Alton, the right of imagination. But Austen is accurate. book. How did Jane Austen create a work and Austen’s brother was a banker. After this If she says the orchard was in bloom, then it without flaw? Literati will have their time, Austen’s letters seem full of weather. surely was in bloom. Her meteorological sense is explanations and doubtless many learned theses. Austen wrote Emma in 1814–15. It is nice to acute, accurately recording the passage of fronts. But, to this illiterate from the numerati, the imagine that the crux of the book, the trip to Box The perfection of the book comes from the science perfects the art. Hill, dates from summer 1814. The lesser details quality of the observation; the science makes the Emma herself is in full bloom, lovely, ready may have been filled in as she wrote. Suppose art. Each graduate student should be set to read for marriage, as the spring of life passes to high then that the book records the weather of an Austen novel before starting a thesis. summer. Day by day, the plot twists with the summer 1814 and winter 1814–15, day by day as Austen painted in miniature on two inches weather report. Is it bright? All is cheerful. Is it she wrote, although the calendar may be of ivory, but she wrote on large issues. In 1772, drizzling? Misery abounds. Or, beware, is it hot 1813–14, when she began the plotting. With Judge Mansfield’s far-reaching judgment ended and sultry? Romance and danger loom. No these assumptions, the course of the book fits slavery in England, helping to create modern doubt there is a learned tome on this beautifully with the weather recorded in The individual liberty; in Mansfield Park the rich, somewhere, but it is a fascinating game to read Climate of London. If so, the story may begin on cultured society can save itself only if it is Emma alongside one of the founding texts of 25 September, pass through autumn to snow at cleansed of its Caribbean evil. The Prince meteorology, Luke Howard’s The Climate of Christmas (now a rare event, but it did occur at Regent, to his credit, greatly liked that book. He London. Christmas 1814), then to a post-Christmas would have seen the point. We should not Emma is set not far from London, near period between frost and thaw (32–41 °F in forget it today. Sanditon, her last work, has a Cobham in Surrey, perhaps at Painshill, where Howard’s record), and the late winter weather of black subsidiary heroine: was Austen going to the eccentric Mr Hamilton, related by marriage early 1815. tackle racism? to Admiral Nelson’s Emma, had created an The crisis in the book occurs just before In her tiny theatre, Austen took on the experimental garden-farm, a ruined ‘abbey’ and midsummer’s day. Austen makes the fascinating greatest of themes. Is it too much to see in her artistic ‘mill’. There was “a sweet view, sweet to observation of an “orchard in blossom”, her masterpiece, Emma, an allegory on Nature the eye and the mind”. The gardens are now famous ‘error’. What are apple trees doing in herself? Perhaps this is imagining too far — or modernized by electricity pylons so obtrusive flower in mid-June? But is this error — or clue? may it be allowable in this journal? But it is a that the observer may be permitted to suspect the The weather was unusual in 1814. The annual good excuse to follow her commendation and hand of a planner. mean temperature was one of the coldest in pour a glass of Constantia in her honour this July. Howard, a chemist and close friend of John Howard’s record, and in May and June the means Euan Nisbet is in the Department of Geology, Dalton, named the clouds: stratus, cumulus, were colder than 1816, the ‘year without a Royal Holloway College, University of London, cirrus, nimbus. He helped to lead the Bible summer’ after the eruption of the Tambora Egham, Surrey TW20 0EX, UK. reconciling this with a scientific world view”; marily knowledge-creating beings, we for us. It is a huge extrapolation! I am wor- “mathematical knowledge is inherently would welcome an unlimited supply of ried about the impression it creates among derivative, depending entirely on our knowl- energy and hence the availability of an sensible nonscientists. There is more to life edge of physics”; “Plato was a very compe- enormous number of computational steps. than the creation of knowledge, as also tent philosopher who believed in telling How can this be achieved? pointed out by Deutsch (somewhat belat- ennobling lies to the public”; “Let us start by Here Deutsch makes contact with Frank edly) in his exposition. imagining some parallel universes stacked Tipler’s “omega-point” theory. The omega- This is a highly stimulating book, full of like a pack of cards, with the pack as a whole point is supposed to be the end-point of the ideas and spurring us on to greater efforts of representing the multiverse”. gravitational collapses after many cycles. imagination; indeed, it lifts the veil that sepa- Even wider horizons are explored in the The many-cycle concept does not seem as rates science and science fiction. Some of the concluding chapter. Deutsch suggests that far-fetched as I once feared. Just before arguments are hard to follow and some seem his four strands together provide an expla- the end-point is reached, the energy gener- quite unconvincing. But they are always nation of reality. The fourth strand is ated may well be such that “an infinite num- striking. knowledge, “which seems a parochial con- ber of memory accesses” and an unlimited Peter T. Landsberg is in the Department of cept until we consider it from a multiverse memory capacity are feasible. So we can Mathematics, University of Southampton, perspective”. Regarding ourselves as pri- then march forward into what future is left Southampton SO17 1NP, UK.

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