Paul Davies, The Goldilocks Enigma. Independent, November 5, 2006. Review by Andrew Crumey.

The prevailing view among scientists, says Paul Davies, is that life and consciousness are interesting bonus features of our universe, not essential components. Davies, however, thinks otherwise. His provocative and fascinating book argues that intelligent life is the reason why our universe exists.

Davies is a distinguished theoretical physicist and an acclaimed populariser of the subject, and this is not the first time he has strayed into territory more usually associated with theologians and philosophers. His previous books include The Mind of God (taking its title from Stephen Hawking’s now notorious assertion that a complete theory of physics would unlock the Creator’s intentions), and Davies won the Templeton Prize for progress in religion, worth more than half a million pounds.

It may come as a surprise, then, to find that the position he takes in The Goldilocks Enigma is one of complete agnosticism. Davies poses a great mystery – the fact that our universe appears tailor-made for life – and offers a number of possible solutions, including God, only to knock them down one by one.

To understand the enigma of the title, think of the way that stars burn. Stars are made of hot gas held together by gravity, and if the force of gravity were stronger than it is, stars would burn far more quickly and expire sooner. Our own Sun would have had a lifetime of only a few million years instead of the five billion it has already enjoyed, and life on our planet could never have had time to evolve. Equally, if gravity were weaker, then stars would burn too dimly, and their energy output would not support life. It seems that the strength of gravity, like baby bear’s porridge, is “just right”.

This kind of reasoning is known as the “anthropic principle”, and gets a standard response from most scientists. The universe appears right for us, they say, because if it were otherwise then we would not be here to ask about it. Nature’s rules are as random as a lottery ticket, and we happen to be lucky beneficiaries of the payout.

The snag, as Davies points out, is that while the lottery gets played every week, the universe began only once, so we are left wondering why nature chose the particular rules it did. Furthermore, the rightness extends to more than gravity; the tiniest changes in the laws of elementary particles would, he claims, make life as we know it impossible.

One answer could be that there are really lots of universes – a “multiverse” embracing every possibility – and Davies devotes the first half of his book to explaining how the multiverse theory has won support among cosmologists in recent years, thanks to developments such as inflation and dark energy. As with all Davies’s books, the explanations here are admirably clear and succinct; and in contrast with much popular physics writing of the last twenty years, there is a welcome tone of humility, perhaps because Davies has spent so much time conversing with people from disciplines outside his own. Though Davies clearly does not favour religious or mystical revelation over scientific deduction, he finds room to praise the insights of St Augustine, Leibniz and others, who approached the problem from a theistic perspective.

Since he is a physicist rather than an historian of ideas, one cannot expect Davies to go much further in acknowledging how modern physics was pre-empted by thinkers such as these, but the multiverse theory he describes closely resembles the so-called “principle of plenitude” – the idea that all things possible must be actual – which Arthur Lovejoy famously traced back to Neoplatonism in his classic study The Great Chain Of Being.

So are we living in a multiverse? Davies remains “cautious”. In a universe where everything is possible, it becomes possible that we are living in a virtual-reality fake, and since these fake universes take up little room there must be more of them than real ones, making us statistically likely to be prisoners of a Matrix-style con trick.

Leibniz had that one covered already: a beneficent God could never do anything so mean. Davies cannot resort to so comforting a notion; his colleague and fellow Templeton winner John Barrow has even impishly suggested that the architects of our fake world might give us hints of its falseness by tinkering with its laws as time goes on. Max Tegmark, another multiverse enthusiast whom Davies quotes, says our universe is real enough, but he offers an estimate in metres of the distance to the identical universe where another you is right now reading another version of this newspaper.

Davies is faced with a dilemma. He cannot believe in an intelligent designer, because of the classic “who made God?” argument. Equally, he cannot accept that our cosmos just happened to turn out right, nor that it is a dot in a multiverse of possible phonies. Davies’s solution is a somewhat dramatic appeal to the more speculative corners of quantum field theory, general relativity and information theory.

Causality, he argues could work backwards, so that the real cause of our universe is its endpoint. And the point our cosmos is evolving towards could be one in which the whole of it becomes conscious. Philosophically minded readers might be reminded here of Spinoza, Kant, Schelling or Goethe, all of whom said strikingly similar things. Davies, it seems, is a new Romantic – if not a postmodernist.

This is a hugely enjoyable book, and in its first half a highly informative one, but sceptical readers will question its initial premise: the so-called enigma. People used to apply the Goldilocks argument to Earth’s orbit, saying it was just the right distance from the Sun – but then it became apparent that far-off worlds such as Jupiter’s moons might harbour life of an entirely different kind. Unless we can discover other beings elsewhere in our galaxy, all argument about whether life is an essential or superfluous part of the cosmos is pure speculation. Our conclusions, as Davies himself admits, are a matter of personal faith.

Daniel Kehlmann, Measuring The World. Physics World (Vol 20 Number 4), April 2007. Review by Andrew Crumey.

Like the Bernoullis or the Osmonds, the brothers Humboldt suffer from interchangeability. Faced with a novel that stars one of them alongside Carl Friedrich Gauss, the first question is: which Humboldt? Author Daniel Kehlmann makes a wry joke out of the problem, quickly identifiying his hero as Alexander von Humboldt, traveller and naturalist. Alexander's equally illustrious sibling Wilhelm, founder of Berlin’s eponymous university, is called simply, "the elder brother".

Making these famously confusable men distinct by leaving one without a name is a subtly ironic device typical of the novel as a whole - a surprise bestseller in Germany where it has outsold J. K. Rowling and Dan Brown to become the country's biggest hit since Patrick Süskind's Perfume. But what of the other hero, Gauss? He is the one we meet first, middle-aged and famous, on his way to a science congress in 1828 at which he and Humboldt will join forces to investigate Earth's magnetic field. His personality is summed up in a few broad strokes: brilliant, arrogant, weary of his second wife Minna and cruel to his son Eugen. Gauss lives for mathematics and has little time for anything else, except dalliances with women of ill repute.

Again, Kehlmann tries to set up a strong contrast with the celibate Humboldt, but here the ploy is less effective. As we backtrack through their separate lives in alternating chapters, the two scientists come across as overly similar. Introspective and misunderstood by their contemporaries, they are perilously close to that stock archetype, the eccentric genius. E. M. Forster defined flat characters as ones summed up in a sentence and unchanged throughout a novel. By that reckoning, Kehlmann's Gauss and Humboldt are pancakes.

That need not be a problem; Forster added that most of Dickens' characters are flat. Like Dickens, Kehlmann is a witty, intelligent writer who wears his learning lightly: in contrast to many novels about scientists, this one is gratifyingly free of slab-like expositions of theory pulled straight off the internet. But while many German readers have found it hilarious, Kehlmann's presentation is thoroughly un-Dickensian in completely eschewing direct speech; all the dialogue is instead reported through Kehlmann's cool authorial voice, a distancing effect that can be off-putting and makes the humour harder to catch.

Humboldt, travelling in South America and observing everything from a solar eclipse to the locals' head-lice, is alert to nature but oblivious to art. His attempt to recite Goethe's poem Wanderers Nachtlied is a comically stilted paraphrase, like an Englishman saying, "I wandered over a hill and saw some daffodils." The translator offers an explanatory footnote, but anyone requiring it is unlikely to chuckle at the joke. The same goes for Kehlmann's frequent digs about German humour and personality, which have obvious appeal to a domestic audience but to outsiders are too much like confirmation of prejudice.

Humboldt's extensive travels provide much of the action, and he is humanised by the presence of a foil, his long-suffering assistant Bonpland. The South American setting is an invitation for magical-realist flights of fancy: Humboldt sights ghosts and a UFO. Gauss's parallel story is inevitably more sedentary but in a way more satisfying, since there is love interest in the form of a mistress, a first wife who dies tragically young, and a second quickly married for convenience. All the most famous Gauss legends are told, some exploded (the one about correcting his father's book-keeping aged three is, it seems, a myth). Gauss's achievements are for the most part name-checked rather than explained; it is only with the prediction of the orbit of Ceres and the founding of non-Euclidean geometry that Kehlmann attempts elucidation, ably working them into the narrative as metaphors. Here, though, the scientifically-minded reader may frown. Gauss's geometric inspiration supposedly comes from his first wife Johanna, who points out to him that triangles on a sphere have an angle-sum greater than one hundred and eighty degrees. Soon the young Gauss is speculating about the gravitational bending of starlight; later he ponders Olbers' Paradox and decides that the ether does not exist. It seems that Kehlmann has got his hero mixed up with Riemann and Einstein.

Hindsight is a dangerous thing, and this novel is full of it. Gauss and Humboldt both speculate constantly about future technology - street lighting, photography, air travel - so that what seems at first like cute humour soon becomes repetitive. Eureka moments are plentiful, always occurring at inopportune times, and the scientists do a great deal of high-level hobnobbing; names such as Goethe, Schiller, and Kant litter the pages as frequently as the Rolexes and Porsches of an airport blockbuster, and serve much the same purpose, offering instant recognition with little effort. A more welcome inclusion is physicist Georg Lichtenberg, well known in Germany as a literary figure but under-appreciated elsewhere.

Parallel lines, Kehlmann tells us, must eventually meet, and the two geniuses finally come together for their work on magnetism. The young Weber arrives too, with a pretty wife who quickly takes Gauss's fancy. This is where the book suddenly comes alive, thanks not to Frau Weber but rather Eugen, Gauss's son, who gets mixed up in political activism. It is as if Kehlmann, suddenly free of his self-imposed biographical script, can at last give free rein to his powers of invention, so that in rapid succession we see a police raid and a seance. Alas, the energy is not sustained: Humboldt departs for Asia, Gauss constructs a magnetometer, and Eugen drops out of the narrative until a final escape to America. I hope Kehlmann follows Eugen into a sequel: he is a talented writer, at his best when unburdened by historical fact.

Philip Ball, The Sun and Moon Corrupted. Guardian, July 12, 2008. Review by Andrew Crumey.

The art of novel-writing is knowing what to leave out. In Philip Ball’s tale of a mad Communist physicist, the person sipping in a café might know the whole of relativity, quantum theory, post-war Eastern European history, and the topography of the city beyond the window – not to mention what he had for breakfast. That’s an awful lot needing to be left unsaid.

Ball is a science journalist and non-fiction author of distinction: I very much enjoyed H2O, his “biography of water”, and he won the prestigious Aventis Prize with Critical Mass. So we can be confident that in this, his debut novel, he will get the science right. The hard part is turning the ideas into drama – though Ball’s plot certainly seems to offer it.

Karl Neder is a Hungarian-born dissident in 1980s Bulgaria, desperately trying to publish work on a machine that will produce unlimited energy. His letters to scientific journals show all the hallmark ravings of a crank – yet there is just a chance that he might be on to something. English journalist Lena Romanowicz sets out to find him, and her illegal wanderings in the Eastern Bloc lead her to the scene of the Chernobyl disaster.

Ball neatly captures the tone of scientific correspondence and international conferences, and deftly draws on a long and ignoble tradition of pseudo-science. Neder, like most cranks, is convinced that Einstein was wrong, and that the scientific establishment is persecuting him. The twist is that Neder is being institutionalised for associating with dissident Soviet physicist Andrei Sakharov; and even the “respectable” scientists Lena interviews agree that Einstein’s theories are incomplete.

How, though, do you communicate the science, without turning chunks of the novel into mini-lectures? Ball cannot crack that one; instead his characters become repositories of information which they exchange for the reader’s benefit. “Do you know about cosmic rays?” one physicist asks another. “Fermi thinks they are protons whisked up by magnetic fields in space,” is the reply, rather than the more plausible, “Of course I do.”

This problem of relaying information – and an urge to pile in as much as possible – swamps the action. Lena, we learn, is a former Goth with a taste for the occult – she mentions incubuses to boyfriend Davey, who asks how she knows about them. “The Displaying of Supposed Witchcraft, by John Webster. Sixteen hundred and somety something.” People who talk like that belong in panel games, not novels; the point of the exchange, it turns out, is to tell us that Lena cannot have children, because of Mullerian aplasia.

A scientific omniscience defines the narrative tone: Lena sees an alcoholic drink as “clear liquor that crept up the sides of its small glass under its own superfluid potency,” while the scientists she meets are “unified by forces” she cannot grasp. The metaphors become a cocktail: a whiteboard is “a palimpsest on which eviscerated theories spilled their entrails.”

Davey falls out of the picture; the novel lacks any further love interest, and the only emotion strongly depicted is the pique of neglected geniuses. “Perhaps”, Lena thinks, “the problem here was something to do with the nature of abstraction.” Her observations on physics apply to the narrative itself. “Explanations are fine… But the abstraction of experience just never seems very… convincing.”

The story takes place over many decades and in several countries as back-stories are filled in, yet the focus is always more on fact and explanation rather than experience and perception. One character meets Einstein in 1950s Princeton: the meeting is preceded by a slab of information about Einstein, completely killing the dramatic impact. Sakharov’s walk-on part is similarly sabotaged. Real-life figures abound, as well as some that are harder to judge: I am still not sure whether the “Iain Aitchison” portrayed here has anything to do with the real-life CERN physicist Ian Aitchison.

The book does offer a large supply of intriguing information, for instance about the pseudo-scientist Viktor Schauberger (mentioned only briefly in H2O); or about Paracelsus (subject of Ball’s previous book The Devil’s Doctor). But novels are not made of fact, and Ball’s greatest handicap as a fiction writer is that he is such a good writer of non-fiction.

Manjit Kumar, Quantum. Telegraph, December 12, 2008. Review by Andrew Crumey.

Even popular science is not safe from Bond mania: Manjit Kumar describes how Einstein, appointed to Prague University in 1911, found the pay-check “a quantum of solace against the creeping sense of isolation.” His book may not be high on thrills but it is certainly an adventure, as he traces the history of quantum theory.

Kumar has taken on a formidable task: modern physics is famously incomprehensible, even to people who work on it. As Richard Feynman supposedly said, “If you think you understand quantum mechanics, you probably don’t.” But did he ever really say that? That’s another problem for Kumar: weighing up the evidence. It would be a rare author who could fully address both the philosophical and the historical issues – an even rarer one who could make it all palatable and entertaining to a general audience. If Kumar scores less than full marks it is only because of the admirably ambitious scale of his endeavour.

His chapters take us through the work of Planck, Bohr, Einstein and other luminaries, mixing biographical facts with an outline of what they did. The section on Heisenberg illustrates both the strength and weakness of the approach. Trying to make sense of the energy levels of atoms – and suffering atrociously from hay-fever – the young Heisenberg went to the North Sea island of Helgoland and had his eureka moment. Measuring first the position and then the momentum of an electron, he realised, would yield a different answer from doing the measurements the other way round. Thus was born his famous uncertainty principle, which Heisenberg interpreted as saying that any observation changes what is being observed.

Kumar accurately and succinctly retells this famous story, but a historian will immediately question the sources, and a philosopher will question the meaning. The source in this case is Heisenberg himself, writing many years later, after he had led the German atom bomb project. No one would take at face value Heisenberg’s claims that he was a reluctant Nazi who wanted the bomb to fail; we should surely be equally cautious about his recollection of conversations with Einstein that supposedly led him to his great discovery. Yet these are reported as historical fact.

Niels Bohr, as Kumar points out, quickly objected to Heisenberg’s interpretation of the principle; but Kumar’s explanation is clumsy. “What prohibits the precise measurement of the momentum of the electron is not the discontinuous and uncontrollable nature of the mometum change, Bohr argued, but the impossibility of measuring that change exactly.” Bohr was notoriously obscure but never quite so circular: Kumar eventually arrives at Bohr’s real point. Saying that measurement alters what is being measured implies a pre-existing “real” value we can never know; yet for Bohr, as Kumar says, “an unobserved electron does not exist”.

It led to a debate between Bohr and Einstein about the meaning of reality itself, in which Heisenberg (and nearly everyone else) sided with Bohr. That great debate forms the heart of Kumar’s book, and is its most enjoyable part. Kumar is a trained physicist, and his explanation of the ingenious “thought experiments” with which the two giants tried to outwit each other is clear and precise. It is perhaps a pity that the whole book was not geared around this episode (as the cover subtitle implies), since it brings into clearest focus the theory’s puzzling core. Most general readers, I suspect, will be more interested in such basic questions than in black-body radiation or electron spin, which get almost equal coverage. Some may also be disappointed that although the narrative takes us up to recent experimental vindications of Bohr’s “Copenhagen interpretation”, there is very little on Everett’s “many worlds” alternative, and nothing at all on quantum field theory, whose predictions are to be tested by the Large Hadron Collider.

Still, although I would not recommend this book to anyone hoping to learn quantum theory without tears, for those who already know at least some of the physics and want a brief, non-academic but thorough history of the subject’s golden age, it is hard to beat, even if nits can be picked. Most interesting to me is the light this book sheds on minor figures whose names are never mentioned in lecture courses, though they made crucial contributions that were taken up by the bigger stars. In physics as in everything else, history gets written by the winners. Kumar thankfully gives some runners-up their due.

Edward Everett Hale, The Brick Moon. Guardian, May 14, 2011. Review by Andrew Crumey.

The term “science fiction” hadn’t been invented in 1870, when the American magazine Atlantic Monthly published the first part of Edward Everett Hale’s delightfully eccentric novella “The Brick Moon”. Readers lacked a ready-made pigeonhole for it, confronted by a fantasy about a group of visionaries who decide to make a 200-foot wide sphere of house-bricks, paint it white, and launch it into orbit.

Jules Verne’s “From The Earth To The Moon” had appeared five years earlier, so Hale’s work was not unprecendented, but while Verne chose to send his voyagers aloft using a giant cannon, Hale opts for the equally unfeasible but somehow more pleasing solution of a giant flywheel.

Hale gives technical details and calculations to support the plausibility of the venture. He even works out the total cost of the bricks (sixty thousand dollars). There is an info-dump about latitude and longitude: the brick moon is designed to orbit from pole to pole so that people anywhere can determine their location by observing it. There are ruminations and speculations – and to be honest, quite a few longeurs, even in a compass of only 25,000 words.

But crucially there is humour. The brick moon gets launched accidentally with some people inside. Those left behind watch through telescopes as the travellers make their own little world, communicating by writing signs in big letters. They grow plants, hold church services, and their moon becomes a tiny, charming parody of Earth.

“The Brick Moon” did not appear in book form until 1899, when Hale was in his seventies, by which time H.G Wells had appeared on the scene and Hale was slipping into obscurity. Nowadays he is little more than a footnote, remembered for having been the first to imagine artificial satellites. But what makes “The Brick Moon” still worth reading is not scientific vision, but sheer joyful quirkiness.

Jon Willis, All These Worlds Are Yours. Wall Street Journal, September 9, 2016. Review by Andrew Crumey.

Imagine that life is discovered beyond the Earth. How would you react? Would it bring about some profound change of attitude? Hold on, it’s happened already. I remember the day, August 7 1996, when NASA announced the presence of what appeared to be microfossils in a piece of Martian rock. My jaw dropped at news I’d longed to hear since childhood: we were no longer alone in the universe. President Clinton stepped onto the South Lawn of the White House and told the assembled press, “If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered.” Yet for all the fanfare, Martian meteorite ALH84001 soon slipped out of the limelight. Here were no little green men, only tiny mineral structures resembling bacteria. And twenty years on, the evidence is still considered inconclusive. It serves, Mr. Willis says in his book, as a warning that any search for extraterrestrial life “may not offer the clear answers that we perhaps naively expect.”

A naive expectation on my part was that his book about the quest for alien life would give substantial coverage to SETI, the Search For Extraterrestrial Intelligence, which focuses on trying to pick up radio communications from distant planets. Leaving aside theoretical arguments against the likelihood of ever hearing anything, the decades of silence endured by SETI researchers are enough to convince Mr Willis that it does not merit public funding. NASA agree: they ceased support in 1995. The project now relies on the generosity of patrons such as billionaire Yuri Milner, and the roughly five million people who donate computer time to SETI@home.

Mr. Willis wishes them all the luck in this and every other world, but as a professional astronomer he is concerned with trying to identify areas with the best chance of actually finding something. There are, he says, two ways we might discover alien life: from a “biomarker” in a planetary atmosphere, or as actual organisms. The first requires powerful telescopes, the second involves robotic space missions. In either case we need to have some idea what we might be looking for.

NASA sets much store by both possibilities, and the anti-climax of ALH84001 has done little to dent hope or deflate hype. In April 2014 it was announced that the Kepler Space Telescope had detected an Earth-size extrasolar planet in the “habitable zone” of a star five hundred light years away. Dubbed Kepler-186f, the planet is at a distance from its parent star that would allow liquid water to exist on its surface, and the media were quick to take up the possibility of a “twin Earth” that could potentially support life. But we don’t know if there is any water on Kepler-186f, let alone anything swimming there.

A better measure of life-bearing possibility is atmospheric composition. The idea originated with James Lovelock, famous for his Gaia hypothesis. Suppose an alien civilisation knew nothing about our planet except the chemistry revealed by sunlight glinting through air at the edge of Earth’s tiny far-off disc. As Lovelock pointed out, the aliens would be very puzzled by the abundance of oxygen. The element was lacking on our planet until the appearance of photosynthesising organisms which produced it as a waste product, making possible the evolution of animals such as ourselves who breathe it, and it’s life that keeps oxygen at a high and fairly constant level. If all life vanished from Earth then so too, over a relatively short geological time period, would the oxygen, consumed in fires, rusting and other reactions. One exoplanet that has yielded to the difficult challenge of having its atmosphere analysed is HAT-P-11b, a Neptune-like world a little over a hundred light years away, imaged by the Hubble Space Telescope and found to have water vapour in its clouds.

But is water necessary for life, and would oxygen be the surest biomarker? As Mr. Willis explains, extraterrestrial life could have evolved in very different conditions, and along very different chemical pathways, from our own. Aside from our oxygen-fed, glucose-burning metabolism there are other reactions that could potentially release energy into living cells: for example, inhaling acetylene and hydrogen, and releasing methane. Interestingly, there is an anomalous abundance of methane on Titan, the largest of Saturn’s moons. Perhaps the gas is venting from reserves beneath the surface, but life is seriously being considered as a possible explanation. Measurements by the Cassini spacecraft have revealed that acetylene and hydrogen are somehow being used up near Titan’s surface, in unknown chemical reactions. So, Mr. Willis asks, is this unambiguous evidence for acetylene-gulping microbes? No, he says; “a good astrobiologist should use life as the conclusion of last resort”.

In 2005 the Huygens probe landed on Titan’s surface, and through an orange fog it showed a terrain strewn with icy pebbles but devoid of any visible organisms. Scientists will need a lot of convincing before reaching for the last resort – as Carl Sagan liked to say, extraordinary claims require extraordinary evidence. Biomarkers detected from afar might never be enough to remove doubt, and if aliens never give us a call then perhaps the only hope of unequivocal proof will be when living goo is scooped from another world and brought back to Earth. That makes our own solar system the only possible search area, and Mr. Willis singles out the prime targets as Mars, Titan, and two of Jupiter’s moons, Europa and Enceladus. His book largely concentrates on these worlds and the challenge of reaching them.

Mr Willis teaches astrobiology to students, and his book conveys great enthusiasm alongside necessary scientific scepticism. The technical details and problems are clearly laid out and discussed – even defining “life” is far from straightforward. All of this makes welcome reading for lovers of science-fact, though it might be disappointing for those raised on science-fiction, and perhaps hoping for a little more by way of historical perspective on a subject that people have been speculating about for centuries. And while the transfer from lecture hall to page generally works well enough, I did wish we could have had rather fewer rhetorical questions. At one point I counted thirteen in three paragraphs.

But while the prose may not always shine, the topic is certainly fascinating. If Mr. Willis could pick only one target out of his shortlist it would be Enceladus; not as far away as Titan, and with the convenient presence of water-spewing geysers whose outpourings could be collected by an orbiting craft. He puts the price tag at $4 billion, pointing out that this is how much the world’s nations collectively spend on defense every single day.

All of which leaves the final rhetorical question: is that a price worth paying?

Gino Segrè and Bettina Hoerlin, The Pope of Physics. Wall Street Journal, October 21, 2016. Review by Andrew Crumey.

In March 1939, at the Navy Department in Washington, Admiral S.C. Hooper was informed of a visitor. “There’s a wop outside,” the desk officer announced. The man in question, who overheard the slur, was Enrico Fermi. He had just won the Nobel Prize and had come to warn of the danger posed by his own recent discoveries in nuclear physics. Fortunately for his newly adopted homeland he had a thick skin. America, not Italy, would build the bomb.

Really it was Nazi Germany that Fermi feared more than the country he and his Jewish wife Laura had fled only a few weeks earlier. Fermi, almost single-handedly, had dragged Italian physics research into the modern age of quantum theory and relativity, and his emigration left Mussolini without the one scientist who might have given him a nuclear weapon. But if things had gone a little differently, might Fermi have done for Il Duce what Werner Heisenberg attempted for the Führer? After reading this superb biography I am left with the nagging thought: maybe.

The book’s co-authors, husband and wife, actually met Fermi, though were too young to receive any lasting impression. Gino Segrè’s uncle, Emilio Segrè, was Fermi’s student in Rome, choosing exile not long before Il Papa, as Fermi was half-jokingly nicknamed on account of his apparent infallibility in physics. Bettina Hoerlin’s father was also an emigré physicist, and like the elder Segrè took part in the Manhattan Project. Given the authors’ personal connections, their own scientific expertise, and the wealth of research they have undertaken, it is clear that they have produced a definitive study of Fermi’s life and work. It is also apparent that even for the people who knew him best, Fermi was enigmatic. Urbane, genial, a team player with a generous spirit, he nevertheless kept his emotions hidden. “Not cold, but not warm either,” was how one colleague described him. According to his daughter Nella, “It wasn’t that he lacked emotions, but that he lacked the ability to express them.”

Fermi’s childhood offers some clues. For the first two and a half years of his life he was in the paid care of a “farm family” so that his parents, a civil servant and a teacher, could cope with their careers and two other children. When finally brought back, he cried with alarm, only to be chastised by his mother who told him, “In this home naughty boys are not tolerated.” The repressed atmosphere worsened when Fermi was thirteen, with the sudden death of his older brother. While the parents withdrew into silent anguish, Fermi increasingly absorbed himself in mathematics, a talent noticed by a family friend who took the boy under his wing. Recognised as a prodigy, Fermi rose through Italy’s most prestigious educational establishments, publishing his first paper in 1921 while still an undergraduate. In the following year Mussolini became prime minister, and much of Fermi’s finest scientific work was to be carried out under the auspices of the Fascist regime.

Fermi’s first major discovery came in 1926; a paper on quantum statistics that put him at the vanguard of theoretical physics. Three years later, when Mussolini created an exclusive academy of artists and scientists to promote the nation’s intellectual achievements, Fermi was offered membership. It came with a substantial lifetime stipend and an expectation that the recipient would join the Fascist Party. Fermi accepted. Both in Italy and later in America he would present himself as apolitical, interested only in physics. Whether this was pragmatism, cynicism, naivety or a further manifestation of emotional withdrawal is impossible to determine.

Arguably his greatest achievement as a theorist was to predict the existence of a new fundamental force, now known as the weak interaction, in 1934. But Fermi was also a supreme experimentalist. He developed a way of producing free neutrons – particles normally trapped within atomic nuclei – and firing them into other nuclei, in the hope that they would lodge there. In this way he and his co-workers soon announced the creation of a new element, number ninety three in the periodic table. The Italian press immediately suggested calling it Mussolinium, but Fermi’s team instead proposed Ausonium, from the Greek name for Italy. In fact, as later became clear, there was no new element in their samples. Instead of enlarging atoms the team had split them; the neutron bullets had provoked fission. Fermi realised that if a disintegrating atom were to eject further free neutrons then the process might continue in a chain reaction.

Fermi’s apolitical stance was shaken in July 1938 when Mussolini began a campaign of persecution against Jews. Fermi’s Jewish father-in-law, an admiral in the Italian navy, remained tragically loyal to his country, and would eventually die in a German concentration camp. Fermi, however, quickly began planning a research trip to America from which he and Laura would not return. His effort to secure a long-term visa was made easier by the Nobel Prize, collected en route.

A few weeks later he was at the U.S. Navy Department, having been asked by physicist Leo Szilard to alert the government to the possibility of creating a nuclear weapon. Fermi proved unpersuasive; so Szilard penned a letter that was signed by Einstein and delivered to President Rooseveldt, initiating what became the Manhattan Project. Fermi’s key role was to use his neutron skills to create the world’s first nuclear reactor. Segrè and Hoerlin’s account of this famous episode is their book’s high point, admirably conveying both the technical detail and the extraordinary tension of the operation. Fermi knew that if he could assemble enough uranium in the right shape, then the naturally released neutrons would be sufficient to initiate the desired chain reaction, producing heat. Removable absorbers could control the rate of reaction: anything from mild warmth to a potential inferno. Fermi’s genius as an experimentalist enabled him to identify impurities of the components as a significant obstacle. In Germany, Heisenberg’s team would fail to reach that insight, leading them down a blind alley in their effort to build a bomb.

Fermi acted as a roving consultant on the Manhattan Project, revealing nothing to Laura, even after witnessing the test detonation where he estimated the yield by calmly dropping scraps of paper and seeing how far they blew in the gust. A decade later, dying from stomach cancer, he calculated the quantities of nutrients being fed through his drip, made predictions of how many more days he might have left, and showed no trace of fear or regret. The bomb, and life itself, were for Fermi interesting problems of science, not matters for moral reflection. One can’t help feeling that had he met a different, Aryan woman, and not had to leave Italy, history might have been very different.

Sean Carroll, The Big Picture. Wall Street Journal, May 13, 2016. Review by Andrew Crumey.

As a boy, Sean Carroll enjoyed going to church in his hometown of Trenton, New Jersey. He liked “the hymns, the imposing wood pews... the mysteries and the doctrine”. He also liked the pancakes afterwards. But as he grew older, something changed. “My transformation to atheism wasn’t dramatic or life-shaking; it just kind of crept up on me.” Carroll is now professor of theoretical physics at the California Institute of Technology, and his book – grandly subtitled “on the origins of life, meaning, and the universe itself” – is a manifesto that will divide reader opinion along familiar party lines. But unlike some in the science-versus-religion debate (most notably Richard Dawkins), Carroll is not on a mission to show that believing in God is as futile as writing letters to Santa Claus. Never hectoring, always tolerant, Carroll presents a seductively attractive picture of a universe whose ultimate laws lie within our grasp. He might even make a few converts. So why do I, an atheist and physicist myself, find so much of what he says frankly fishy?

Carroll describes his philosophy as “poetic naturalism”, a term that immediately seems set to lure in those of a syncretic disposition who see art and science as a unity. He quotes the poet Muriel Rukeyser, “The universe is made of stories, not atoms”, which sounds like the sort of poststructuralist orthodoxy that long held sway in fields of academia remote from Carroll’s own. But he inverts Rukeyser’s maxim. The universe is made of “stuff”; not atoms, but something more fundamental. That’s the “naturalism” part. We tell stories about the stuff: that’s the “poetic” aspect. So really, a better term might be “prosaic naturalism”, or even just good old-fashioned materialism.

“What is the fundamental nature of reality?” Carroll asks. “Philosophers call this the question of ontology – the study of the basic structure of the world.” Alert students of Metaphysics 101 will at this point raise a hand to say that ontology is instead the question of what “being” means. For most of us, the study of the basic structure of the world is called theoretical physics. The question of how exactly that superbly successful science relates to “the fundamental nature of reality” is left begging.

And what about all those “stories” we tell? Since they’re about real stuff, some are presumably more true than others. Carroll invokes the metaphor of a “planet of belief”: a body of knowledge held together by the “gravitational pull” of mutual consistency. According to Carroll, “we should be constantly testing and probing our planets of belief for inconsistencies and structural deficiencies”. Of course, “The real problem is that we can imagine more than one stable planet”, so how do we choose which to live on? A “habitable” planet, says Carroll, “necessarily includes some shared convictions about evidence and rationality, as well as the actual information we have gathered about the world”. Put more succinctly, his position is that science is the only authentic access to genuine knowledge about reality, and science is a hierarchy of “stories” with theoretical physics sitting at the foundation.

So what, then, is the basic “stuff” about which all consistent, coherent stories are ultimately told? It is not, of course, the atoms that were long ago smashed into smaller pieces, nor even the quarks and leptons whose speeding tracks are spotted in particle accelerators. It is instead the quantum fields whose vibrations we detect as matter and radiation. And here it is I who must raise a hand from the back of the class and ask: is a quantum field “stuff” or “story”? An anecdote that may or may not be true says that the great theorist Paul Dirac was once asked what an electron was, so he wrote an equation on the blackboard, pointed to a symbol in it, and said, “That’s an electron”. This is essentially Carroll’s view, and as the anecdote shows, it is of noble lineage. But it remains debatable, and Carroll’s evasion of that issue undermines the version of materialism he takes for granted in his “poetic naturalism”.

To an extent, his idea of real stuff and stories about stuff resembles the work of the French philosopher Alain Badiou, who has sought to ground materialism on a quasi-mathematical basis, presenting ontology (“being”) as set theory, and phenomenology (“appearance”) in terms of a considerably more abstruse framework. Badiou’s protégé Quentin Meillassoux has also developed a highly sophisticated approach to what has been termed “speculative materialism”. Carroll’s pre-Kantian poetic naturalism is naive by comparison, in a technical and not pejorative sense. The hardest part of philosophy is understanding the questions, and Carroll knows that what his readers are looking for is answers, which he presents with admirable clarity.

What he gives us in this book, once we accept the empiricist ground rules, is a highly enjoyable tour through a very wide range of topics. Theoretical physics takes centre stage, but there are also excursions into evolution, consciousness, and the ultimate fate of the universe. The tone is unfailingly engaging; even if you don’t agree with what he says, you are unlikely to be enraged by such an urbane lecturer, more likely enthralled. Still, no matter how basically sympathetic I am towards his position, I can’t help feeling that in his opposition to religion he’s really shooting at straw men. “For the sake of keeping things simple,” he writes, “let’s divide all the possible ways of thinking about God into just two categories: theism (God exists) and atheism (no he doesn’t)... And for the sake of being definite, let’s imagine that we’re talking about God as a person, as some kind of enormously powerful being who is interested in the lives of humans.” That leaves out a lot of possibilities. Carroll appeals to evidence, but interestingly expresses faith in the speculative “many worlds” interpretation of quantum theory. He doesn’t believe in God, but presumably believes in the actual existence of another universe containing another Sean Carroll who does. I wonder what sort of book his other self would write?

Paul Halpern, The Quantum Labyrinth. Wall Street Journal, December 8, 2017. Review by Andrew Crumey.

What’s the square root of four? If you said two you’re half right: the full answer is plus or minus two. Every number has two square roots, and a similar doubling can occur in equations of physics. When Paul Dirac melded quantum mechanics with special relativity to obtain an expression for negatively charged electrons, he realised there must be an additional solution with positive charge, later found experimentally and dubbed the positron. For a certain young graduate student and his supervisor, an analogous trick suggested an even more remarkable reversal: that of time itself. Hence the subtitle of Paul Halpern’s book: “How Richard Feynman and John Wheeler Revolutionized Time and Reality”.

The labyrinth of the main title aptly signals the problem Professor Halpern faced as author. Should it be a dual biography of Wheeler and Feynman, or an exposition of their ideas? An exploration of their key early collaboration, or a wider survey of their long careers? In fact Professor Halpern attempts all of these, to differing degrees and with varying levels of success. He is at his best when explaining concepts of physics, the subject he teaches at the University of the Sciences in Philadelphia. Less satisfying is his effort to convey the personalities of the two geniuses, whom he generally renders by way of simple contrasts: Wheeler the staid philosopher, Feynman the impish bongo-drummer. Admittedly, much has already been written about both men, especially Feynman, whose complexities and flaws are not explored here. And inevitably it is the colourful Feynman who tends to steal the show.

As a student in the 1930s, learning quantum theory from Dirac’s writings, Feynman asked: can an electron interact with itself? Standard arguments said yes: the particle should be affected by its own electromagnetic field, rather like someone finding difficulty running because of their own weight. Yet this led to “divergences”: the calculated self-interaction was infinite. Curing the problem would eventually win Feynman the Nobel Prize, though only after spending years on an incorrect approach.

Suppose there was no field, instead only particles magically influencing each other at a distance without any intermediary substance. It would answer the question of self-interaction, but could it be possible? Wheeler, Feynman’s thesis supervisor at Princeton, immediately saw both a problem and its possible solution. Shake an electron and another far off will shake in response: this is how our television and phone networks can function, and the signals are mathematically described by equations found by James Clerk Maxwell in the 1860s. If Feynman’s proposal was correct, then surely the wiggling of the receiving electron should in turn influence the sender, potentially leading to the same infinite circularity Feynman sought to avoid. But like the square root of four, Maxwell’s equations have an extra solution: a signal going backwards rather than forwards in time. It had always been dismissed as an artefact; now Wheeler suggested it as reality, a way of cancelling the surplus interaction. He went even further: Dirac’s positron could likewise be an electron in reverse. Together they hatched what came to be called “absorber theory”. A nervous young Feynman presented it before an audience that included none other than Princeton’s most famous resident, the elderly Albert Einstein who was, says Professor Halpern, “friendly but neutral”. Others such as Wolfgang Pauli were more hostile, but Wheeler and Feynman pressed on with their theory.

They were interrupted by global events: Feynman’s involvement with the Manhattan Project and brief marriage to the tragically sickly Arline Greenbaum provide a compelling interlude in Professor Halpern’s narrative. Then as war ended, Feynman returned to the absorber theory. Its key feature was a mixing up of times – past and future – in contrast to the more usual procedure of modelling systems at successive instants. This proved to be its strongest point, even when the theory itself fell foul of experimental results that contradicted it. As Professor Halpern ably explains, Feynman had developed a calculation technique well suited to the time-distorting effects of special relativity. Reversing his previous position, Feynman now insisted that electrons really do self-interact – and with his new technique, called a “path integral”, he could recast quantum theory in a way that eliminated the previous infinite results, employing a cancelling procedure dubbed “renormalization”. This was the work that eventually took him to Stockholm where, in his 1965 Nobel Lecture, Feynman said that as a young man he had fallen in love with absorber theory, and “like falling in love with a woman, it is only possible if you do not know much about her, so you cannot see her faults.” He had readily abandoned that theory when it no longer served his purpose: the sign of an excellent theoretician, though not necessarily the best companion, as people such as the second of his three wives might have attested.

Feynman’s path integral splits quantum events into a sum of all possible ways they might occur. Wheeler called it a “sum over histories”, a notion subsequently likened to the alternate-history scenarios of Philip K. Dick or the branching realities of Jorge Luis Borges’s famous story “The Garden of Forking Paths”. Feynman opposed that interpretation, but it is the Borgesian labyrinth that Professor Halpern’s title hints at; and as his narrative continues we encounter others among Wheeler’s students, including Hugh Everett and Bryce DeWitt, whose “many worlds” interpretation of quantum mechanics has further stimulated scientific speculations about multiple histories and parallel universes. In fact, as the theorists and theories multiply – reflecting the broad interests of Wheeler, Feynman and the generation they mentored or inspired – we almost seem in danger of another kind of infinite divergence. Every book, says Professor Halpern, requires an “Ariadne’s thread... a linear narrative that serves as a guide through the greater labyrinth of information.” The lives and careers of Wheeler and Feynman are meant to be the main thread here, but one must sometimes look hard to see its trail through the tempting tangle of corridors. Their strange joint theory might have been thread enough, no less absorbing or amazing.

Raymond Tallis, Of Time and Lamentation. Wall Street Journal, August 3, 2017. Review by Andrew Crumey.

“What is time?” Saint Augustine wondered. “If no one asks me, I know; if I wish to explain to whoever asks, I know not.” He thought that the present alone exists, but a millennium and a half later we learned that time is the fourth dimension, one we might even travel in. According to Einstein, “For us believing physicists, the divide between past, present and future has only the significance of an illusion, albeit a stubborn one.” Augustine would not have been happy with that, and nor is Raymond Tallis, whose massive philosophical study seeks to “reclaim time from the jaws of physics.” It is a worthy aim and a persuasive argument.

Tallis says we err when we think of time in spatial terms, as a dimension or line, then take that image literally. We foresee the future and look back on the past, but that doesn’t mean last year is actually standing somewhere behind the present one, or that the next is trundling towards us along some temporal track. After all, we know that a pay rise is not an actual elevation on the dimension of money, and a heatwave may make thermometers soar but doesn’t set us wondering if we could travel through temperature. The fourth dimension of relativity is an “imaginary” one, involving the square roots of negative numbers. It makes beautiful mathematical sense, but how does it relate to actuality? Is the universe really the bendy spacetime so graphically presented to us in physics documentaries, or are those pictures as schematic and artificial as a map of global population or a graph of mortgage interest rates? Physicists insist on the reality of their equations, but if you spend your entire career working with something, no matter how intangible, it will get to feel pretty real.

The issue was raised over a century ago by Henri Bergson, who suggested a simple experiment. Take a pin in one hand and prick it into the other, pressing gradually harder. You feel pain, of course; but is it a single sensation that grows in intensity, or a succession of different ones: a tickle, a prod, a prick, an ouch? Bergson said we fool ourselves into thinking the former when really it’s the latter. Our perceptions are qualitative, not quantitative; and this, he said, must include our sense of time. In physics, every moment is an equivalent mathematical point. In life, every moment is unique.

Bergson was hugely famous and influential, yet fell out of fashion, his theory of time supposedly made redundant by relativity. It is exactly that error which Tallis now seeks to rectify. The issue is not of objective versus subjective time: we all know that guessing how many minutes have passed during a boring film or a hot date is as difficult as estimating the height of a tree, the weight of a suitcase, or the number of sweets in a jar. No, the issue is the claim made by Pythagoras, Galileo and most physicists today, that ultimate reality is mathematical, all else being mere appearance or even, as Einstein suggested, an illusion.

Clocks measure something real, Tallis has no quarrel with that, so he has comparatively little to say about Bergson’s English contemporary, J.M.E. McTaggart, whose “proof” of the unreality of time nevertheless continues to figure in most philosophical discussions of the subject. In fact, Tallis almost seems to assume the reader will know McTaggart’s tricky argument already, slipping in his “A” and “B” series like tiresome relatives one can’t avoid but hopes won’t stick around too long. Herbert Bradley, who had a different proof of time’s unreality, is never mentioned at all; nor J.W. Dunne, whose pseudo-scientific theory of multiple time dimensions intrigued J.B. Priestley and J.L. Borges. Tallis is more interested in ideas than personalities. He highlights the circularity of saying time “passes” when there is nothing for it to pass through, or any stuff to flow, nor any pace except “one second per second”. Attempts to explain time merely slip it in surreptitiously as motion or change.

Tallis’s original intention, twenty five years ago, was to write “a collection of short pieces of what I hoped would be poetic prose”. By the late 1990s it had become a thousand-page novel, discarded and by now “turning to peat”. In 2009 he began what has finally appeared: a mere seven hundred pages, largely composed in various pubs. Of Time and Lamentation is the author’s philosophical conversation with himself, often prolix and repetitive, even forgetful of its own train of thought: at one point the same passage of Kant is quoted twice, in full, within a single paragraph. It is a book of frustrations. Tallis ultimately admits, “I have been more successful in saying what time is not than what it is”. But we know that in philosophy there are no answers, only the possibility of framing old questions in new ways. For all its flaws, this is an absorbing book that will reward the patient reader with a deeper insight into the problem, if not its solution.

And what of eternity? To some it means endless time, to others something timeless. The latter was how Boethius conceived it, writing The Consolation of Philosophy as he awaited execution in 524AD. Someone looks down from a high mountain onto the desert plain below where a caravan slowly crawls. It is a metaphor of God’s view of us as we make our collective journey across time’s landscape. Einstein’s remark about the illusion of time, written a few months before his own death, was essentially an updated version of Boethian eternalism, or as William James called it, the “block universe”. What’s wrong with the theory? Only that it provides no explanation of why time should exist at all, or how any particular moment becomes “now”. Physicists have no answer to that, and Tallis thinks they never will. His final response to Augustine’s question? “Time is time.”

Adam Becker, What Is Real? Wall Street Journal, March 16, 2018. Review by Andrew Crumey.

If quantum mechanics can be said to have a capital city it is surely Copenhagen, birthplace of physicist Niels Bohr, and of a version of his theory expounded in every textbook. Yet the “Copenhagen Interpretation” has been questioned many times, and Adam Becker tells a fascinating if complex story of quantum dissidents. Two of the most important didn’t only displease Bohr: they attracted the attention of the FBI.

Bohr’s mumbled utterances were famously obscure, adding to his sage-like status, but his views were clarified in part by debates with Einstein, whose remark that “God does not play dice with the universe” encapsulated a key issue. Each face of a dice has a one-in-six chance of landing uppermost when the cube is rolled; but if we knew enough about the forces on its atoms, we could predict exactly which number would come up. Quantum odds are instead governed by “wave functions”, and the question was whether those waves arose from deeper “hidden variables” – analogous to the atoms of a dice – or whether probability itself was a fundamental feature of reality. Einstein thought the former; the idea of unexplained randomness horrified him.

A further issue was that wave functions are spread over space, particles aren’t. When an electron hits a detector, does its wave instantaneously collapse to a point? Bohr proposed what he called “complementarity”; the fundamental units of matter or light were neither wave nor particle, but could be considered either. An alternative theory imagined particles riding on “pilot waves”, as physically real as dice. Then in the 1930s it was proved mathematically that under very general assumptions, hidden variables could not exist. This “no-go theorem” killed much of the opposition to Bohr, and few questioned its validity. One who did was Grete Hermann. “But nobody listened to her,” Becker writes, “partly because she was an outsider to the physics community – and partly because she was a woman.”

Another critic was David Bohm. A protegee of Robert Oppenheimer on the Manhattan Project, Bohm revived pilot-wave theory in a 1952 paper. That, and his left-wing political activism, made him an outsider in two senses. He was suspended from his post at Princeton – despite Einstein’s intervention – and moved to Brazil, where he found himself having to surrender his U.S. passport. Eventually he settled in London, pursuing his own kind of physics until his death in 1992.

Bohm’s pilot waves circumvented the no-go theorem at the cost of allowing what Einstein had called “spooky action at a distance”, where a measurement in one place seems to influence what could instead have been measured elsewhere. This idea – “non-locality” – was taken up by John Bell, a young Irish physicist working at the CERN laboratory in Switzerland, now the home of the Large Hadron Collider. Bell showed how the spooky non-locality might perhaps be tested experimentally.

Bohm and Bell play two of the starring roles in Becker’s book. The third is Hugh Everett, whose answer to the problem of wave-function collapse was that they don’t: the universe instead branches into every possible outcome. After presenting the theory in his PhD, Everett worked as a defence analyst and consultant, able to fund the hedonistic lifestyle he favoured. On one occasion, seeing what were clearly government agents on a flight, he took photographs of them, saying they were “for my files”. Visited later by the FBI, he assured the officers it was a joke, not mentioning that his own security clearance was probably far higher.

The three rebels make intriguing heroes in Becker’s informative and enjoyable book. Their stories illustrate how personality, prestige and prejudice can play a role in elevating or marginalising ideas in physics, as in any other branch of academic life. Becker takes a frankly partisan view, and while he acknowledges technical problems on all sides of the debate, his reasonable desire for a coherent narrative somewhat elevates the claims of the dissidents against the mighty Bohr. At times Copenhagen almost seems like the heart of an evil empire.

Moreover, it’s not entirely clear what the “Copenhagen Interpretation” really is. The term was coined by Werner Heisenberg, possibly as part of his own post-war rehabilitation strategy. Having led the Nazi atom-bomb project, he was keen to be back in the right club, and played up the idea of a solid consensus among physicists. The success of quantum theory as a predictive tool led many to take the pragmatic approach of “shut up and calculate”, a phrase often attributed to Richard Feynman but originating, Becker says, from an article by David Mermin. Philosophical questions could be laid aside in favour of investigating experimental results. Becker argues that the strategic and economic significance of physics in the U.S. after World War 2 helped reinforce this attitude, strengthening resistance to alternative views.

There is doubtless some truth in that, but while Becker’s admirably thorough research has included interviews with numerous notable physicists, his tales of young researchers committing career suicide by challenging Copenhagen orthodoxy should be taken with a grain of salt. There are many reasons why a presentation can go badly or a career can stall, and it’s not always because the world is out to get you. The theories of Bohm, Bell and Everett all had problems of their own, and grey areas of contention are often presented here as settled issues, painted in overly sharp contrast. Bell’s tricky experiment was perfected and successfully performed by Alain Aspect in 1982. For Becker, it stands as a blow against Copenhagen. For many physicists it was the exact opposite, a posthumous victory of Bohr over Einstein.

History is written by the victors, and journalism is the first draft of history. Since the quantum contest is still ongoing, we should perhaps consider this book to be journalism rather than history. That is in no way meant pejoratively: Becker has written an excellent, accessible account of an intricate story. Whether he’s chosen to wear the right uniform will be for future readers to judge.