Julian Barbour, The Janus Point (Wall Street Journal)

The author describes this book as "a song of thanks to the cosmos." It's not the catchiest of tunes and takes quite a bit of getting used to, but it's worth the effort because Mr Barbour's theme is the greatest mystery in physics: the meaning of time.

He has been studying the problem for decades, and his 1999 book The End of Time was a bestseller. Since then, his fundamental outlook appears not to have changed, though the mathematical approach has. The Janus Point is largely devoted to explaining the new formalism, though first we need to grasp the main pillars of his philosophy.

Like many physicists, Mr Barbour believes the past, present and future co-exist. We don't know what will happen tomorrow, and think we can change it, but it's already there. Time is like a movie strip; each frame is a single moment. According to Mr Barbour, our consciousness is able to hold a group of frames in a way that feels like continuous flow.

What makes the movie run forwards rather than backwards? In Slaughterhouse-Five, Kurt Vonnegut memorably described aerial bombing in reverse. Martin Amis inverted the entire chronology of his novel Time's Arrow. Physicists have suggested various explanations for the arrow of time, the most popular being connected with entropy. This is what Mr Barbour focuses on, and it raises a paradox. The second law of thermodynamics says that entropy - commonly thought of as disorder - inexorably rises over time. Then the big bang must have been a highly ordered, very special state. One answer might be that God chose it that way - or it was a chance fluke, without which we wouldn't have come into existence. Another response would be to question how entropy is defined. Some physicists have argued that gravity needs to be included in the calculation. Mr Barbour goes further, saying that while classical thermodynamics dealt with gases in containers, the universe has no walls. Rather than thinking outside the box, Mr Barbour throws the box away completely. In a boundless universe, he claims, we should think not of rising disorder but instead of growing complexity.

For the next pillar of his argument, imagine a film being projected onto a screen. Move the screen further away, and the picture gets bigger, but is otherwise unchanged. Tilt or bend the screen, and the image is distorted. If everything in the universe suddenly doubled in size, things would appear no different. If instead every angle doubled, we would certainly see a change. For this reason, Mr Barbour views shape as more important than size. The height and width of the screen could be measured in inches or centimetres, but the aspect ratio is the same, whichever units are chosen. Inspired by nineteenth century physicist Ernst Mach, Mr Barbour seeks to base physics entirely on numerical proportions. Each frame of the cosmic movie is a particular arrangement of every particle in the universe - a "shape" - where relative rather than absolute distances are what count.

The actors in our movie - the particles of the universe - are moved by forces exerted on one another. In what Mr Barbour terms the "minimal model" there are just three particles; a triangle linked by Newton's law of gravity. We can imagine infinitely many arrangements of this triangle; single movie frames on the cutting-room floor, needing to be spliced together into a coherent film. To do it, Mr Barbour introduces a mathematical framework called shape space, and a process of "best matching". This, he claims, is the law that makes one instant of time follow another. From three particles we move to any number, still governed by Newtonian dynamics. And this is where the point of the book's title comes in. Laying a section of our completed film strip on a table and looking along it from left to right, we see particles moving apart. It appears very much like an expanding universe. Tracking back from right to left, we see the particles come together and merge at a single point. That's the beginning of the universe, though not of the film strip. It's only the middle - the Janus point. Continuing leftwards we see particles moving away from each other, a big bang in reverse. So there are two universes, not exact mirror images of each other, but looking in opposite directions of time, like the Roman god.

The details take a lot of unpacking. On page 245 Mr Barbour says, "By now the reader may be impatient to know whether a Janus point... exists in general relativity." My impatience had started about 200 pages beforehand. Newtonian dynamics are a good approximation of reality, but how true to life is the double-faced universe they allegedly imply? Modern cosmology is based on quantum theory as well as general relativity, and the biggest surprise to me on reading The Janus Point was how long it took to get to where the The End of Time began. Mr Barbour's initial problem with time arose from attempts to construct a consistent quantum theory of gravity, and his first book dealt largely with that issue. In the same way that single particles can be associated with a quantum wave function, the universe as a whole should, it's assumed, have a wave function - yet the resulting mathematical expression appears timeless.

In The Janus Point Mr Barbour grapples only briefly and speculatively with the quantum extension of his double-universe theory. He has more to say about relativity, which is very interesting, though it also steepens the difficulty gradient quite considerably. Having worked on this erudite subject for so long, Mr Barbour can no doubt juggle with Hessians, Yamabe invariants and "nonhomothetic total explosions" in his sleep. For lesser mortals like me, it's hard to picture them while fully conscious. Still, this final section is where he makes his broadest and boldest claims, offering an alternative to the standard cosmological theory of inflation.

Loose ends remain. Is the total energy of the universe zero, as Mr Barbour's theory requires? If the negative energy of gravitation exactly cancels the positive energy of everything else, then yes. But it's a guess. Are all the things we measure, such as the speed of light or strength of gravity, fixed by hidden ratios? Who knows. And there was a further question that I kept asking, though Mr Barbour leaves it hanging almost until the very end. His version of the movie analogy involves a kingfisher, and he says, "Even if, as seems entirely reasonable to me, our brain does contain in any instant several ‘stills' of the kingfisher in flight, where is the projector that turns them into motion in our minds?" Hidden within the metaphor is time itself, driving the movie or the viewer's mind. Mr Barbour says that "time is abstracted from change", but what is abstracted - as he acknowledges - is duration, the thing that clocks measure and physicists label as t. Lived time - the kind that matters to us - is something else. Not a succession of instants, but the thing that turns one instant into another.

Michael D. Gordin, Einstein in Bohemia; Andrew Robinson, Einstein on the Run (Wall Street Journal)

"I must confess that biographies have rarely attracted or fascinated me," Albert Einstein wrote in 1949, prefacing one about himself. Hundreds more have appeared since then, and into this crowded field come two focusing on particular topics in Einstein's life: his residency in Prague before the First World War, and his flight to Britain before the Second. They could hardly be more different.

Michael D. Gordin describes Einstein in Bohemia as "an experiment in thinking historically." His book is really about Prague as much as Einstein; its stated "point of departure" is the physicist's professorship in the Bohemian capital from April 1911 to July 1912, but the narrative looks "forward throughout the twentieth century and backward to the distant centuries that still reverberated in local memory." It is a book of connections and digressions, meticulous in scholarship and erudite in tone, that may be a frustrating read for anyone simply wanting to know what Einstein actually did during those sixteen months.

Einstein's chief problem was to extend relativity theory from objects moving at constant velocity to ones that are accelerating. Falling objects accelerate, so Einstein knew his general theory had to involve gravity. His great insight was to regard gravity and acceleration as equivalent. A person falling in a cage through a horizontal jet of water would see the transiting jet appear to bend. Replace falling by gravity, and water by starlight, and the conclusion is that stars should seem shifted as the Sun passes before them.

It was in Prague that Einstein first made this prediction, as Mr Gordin explains, though he does not go much into the most important aspect of Einstein's calculation, which is that it was wrong. In fact Isaac Newton had predicted the bending of starlight on the false assumption that light is exactly like a stream of particles. Einstein used waves instead, making it all more complicated, but his Prague calculation gave the same result as Newton's. It was only after leaving Prague for Zurich that Einstein perfected general relativity and saw that the correct answer was double what he had previously found. A solar eclipse in 1919 provided a way of deciding between three possibilities: no bending of starlight, or Newton's value, or Einstein's. Vindication of the latter brought instant worldwide fame.

Einstein's other problem in Prague was his marriage. He began seeing the woman who was to become his second wife, Elsa, and though he would remain with her until her death in 1936, Einstein later wrote that as a husband he had "twice failed rather disgracefully". Mr Gordin touches only briefly on the domestic situation; he is more interested in Einstein's intellectual contacts, and the further connections leading from those. One tantalising episode is Einstein's meeting with Franz Kafka, though Mr Gordin rightly dismisses that brief encounter as biographically insignificant. He does however make extensive forays into other figures associated with Einstein, such as Kafka's friend Max Brod, or Philipp Frank, author of the 1949 biography that Einstein reluctantly consented to. The result is a nonlinear narrative of historical dot-joining, dense in content and admirable in academic rigour, that will doubtless become an essential reference for anyone researching what has usually been seen as a minor chapter in Einstein's life.

Andrew Robinson's Einstein On The Run is more mainstream in style and broader in appeal. Subtitled "How Britain Saved the World's Greatest Scientist", it promises the intriguing story of Einstein's spell under armed guard in the English countryside after fleeing Nazi death threats in 1933. Those few weeks, however, form an even narrower slice of history than Einstein's time in Prague, and are not enough to fill a book. What Mr Robinson instead provides is a highly readable, fairly conventional summary of Einstein's life and work, coloured by his British connections, and with his hideout in rural Norfolk serving as an entertaining climax.

Einstein was a polarising figure in Germany throughout the 1920s, even condemned by some Jews who feared his outspoken pacifism could only exacerbate anti-Semitism. Einstein and Elsa left the country just before Hitler came to power in 1933, staying initially in Belgium while their German properties were raided and their assets seized. Einstein's photograph was published with the menacing caption, "not yet hanged".

Stirred by their plight, an English politician named Oliver Locker-Lampson wrote offering his London residence as a refuge. He was a complex character who had initially been an admirer of Hitler, even creating a quasi-fascist organisation that became known as the Blue Shirts, though he was never an anti-Semite and opposed Nazi racial policies. Einstein took up the offer, and once in England was taken to meet Locker-Lampson's fellow-Conservative MP, Winston Churchill. Soon after, Einstein was in the House of Commons to hear Locker-Sampson put forward a bill that would give Jewish refugees British citizenship with right of abode in Palestine. Einstein had misgivings, fearing the disruptive influx such a measure would create.

Exaggerating the danger from would-be assassins, Locker-Sampson moved Einstein to his secluded Norfolk retreat. The flamboyant ex-serviceman had himself photographed guarding his guest there, rifle in hand, prompting press mockery about the hideaway whose location was no secret. Locker-Sampson's protection included opening Einstein's mail, even from Elsa still in Belgium, so it is not surprising that Einstein soon tired of it. Even so, he afterwards said how much he had enjoyed the solitude there, a refreshing change from the enforced socialising his celebrity status necessitated. It prompted Einstein to make the bizarre suggestion that young theoretical physicists should perhaps be allowed to work as lone lighthouse keepers, free to think in peace. Newspaper cartoonists had fun with that idea, and a lighthouse keeper wrote to the Manchester Guardian pointing out that the job in fact required undivided attention.

In October 1933, Einstein sailed with his wife for America. Why did he choose Princeton over Oxford? Mr Robinson suggests several reasons. One was Einstein's dislike of English stiffness and formality. Another may have been a wish to get far away from "insoluble family entanglements" - his ex-wife Mileva and mentally ill son Eduard in Zurich. Most important, perhaps, was that in Princeton Einstein could be left alone to pursue his quest for a unified field theory of gravitation and electromagnetism. Not quite a lighthouse, but close. All he really cared about was physics - and we can be grateful for that.

David Lindley, The Dream Universe (Wall Street Journal)

Fundamental physics, says David Lindley, has lost its way. "I am ready to declare that research in this area, no matter its intellectual pedigree and exacting demands, is better thought of not as science but as philosophy." His book aims to show how physics emerged out of airy speculation in the seventeenth century, and in recent years has sunk back into it. This is not a book that will please philosophers, nor indeed historians, though physicists will find the argument a familiar one.

The problem, says Mr Lindley, has been an excessive reliance on "mathematical elegance and beauty and whatnot" in fields such as "particle physics, the unification of gravity with quantum mechanics, and cosmology". The first of those areas may seem a puzzling inclusion, given the triumphant discovery in 2012 of the Higgs boson after it was predicted mathematically. That, apparently, was an exception to the rule. "The Higgs mechanism is no one's idea of beautiful mathematics... There's nothing natural or inevitable about it, certainly nothing elegant. But it does its job." The same applies to one of the biggest breakthroughs in astronomy of recent decades, the confirmed reality of a previously theorised quantity driving universal expansion at an accelerating rate. "The beauty or otherwise of the cosmological constant is a nonissue. It has practical value, and that's what matters."

What Lindley really has in his sights is the middle term of his list, the quest to explain nature's fundamental forces - gravity, electromagnetism and nuclear interactions - in a single theory. Lindley was a PhD student in the early 1980s when a "theory of everything" appeared imminent. One promising candidate, supergravity, was followed by another, superstrings. Then both were shown to fall within a larger framework having multiple versions. Theories proliferated faster than any experimental data that might favour one over another. Mr Lindley's first book, The End of Physics, claimed the "ambition was delusional". Thirty years on, The Dream Universe is his way of saying he was right all along - physicists are no closer to the final answer.

The reason, he claims, is that they're going about things the wrong way. Alternatively it might simply be that the problem is very hard. Another possibility is sociological - in a competitive academic world it's usually safest to stay in the mainstream, even if that happens to be a blind alley. Mr Lindley's approach is to view the question historically. And that, I think, is where he goes wrong.

Richard Feynman wrote in QED of a "‘physicist's history of physics'... a sort-of conventionalized myth-story that the physicists tell to their students, and those students tell to their students." The Dream Universe is a physicist's history of physics. First, according to Mr Lindley, there were philosophers such as Plato and Aristotle, the former having a "positive disdain for practical knowledge", while the latter "compiled enormous volumes on the variety of animal life... although his larger purpose was the epistemic goal of understanding the true nature and purpose of life rather than such technical ones as improving animal husbandry or writing cookbooks." Next came the "stodgy orthodoxy" of Christianity until at last "the scientific method of enquiry began during the Renaissance in Europe, and the individual most powerfully associated with its genesis is Galileo Galilei." When Lindley calls his first chapter "Galileo invents science" he isn't being hyperbolic - he really means it.

What Galileo supposedly invented was the idea of using "observational and experimental information to infer a reliable mathematical rule." Specifically, he showed that the path of a flying cannonball is a parabola. That was certainly great science, but was it the first instance? How about Archimedes in his bath tub, or countless other examples one guesses would all be dismissed by Mr Lindley as isolated exceptions?

The modern rot set in, he maintains, with theoreticians such as Hermann Weyl and Paul Dirac, who spoke of beauty as well as truth in physics. "Galileo would have been aghast. He had no patience with mystical blather...". I'm not so sure. Take, for instance, Galileo's most famous book, his Dialogue on the Two Chief World Systems, where he said arguments for placing the Sun rather than Earth at the centre of the universe "must be even more beautiful; infinitely more beautiful, and the others extremely ugly, if that metaphysical proposition is correct which says that the true and the beautiful are one and the same, as are likewise the false and the ugly."

Mr Lindley complains, "the more physics pushes into the subatomic world, the more arcane the mathematical tools it draws upon." But take Galileo again, and his Dialogues Concerning Two New Sciences, in which he used some pretty arcane mathematics to "prove" the existence of atoms. A line contains an infinity of points - remove half and an infinite number remain. Hence, Galileo claimed, atoms are points of no size, separated by similarly infinitesimal vacuums holding everything together. I've shortened the argument; Galileo got there after some esoteric geometry and speculative philosophy - a string theorist ahead of his time.

Mr Lindley says that aged sixteen he tried reading Newton's Principia, and despite knowing the theory, found the book incomprehensible. The reason, he maintains, is that Newton deliberately chose an archaic style, "unable to unburden himself immediately of the old tradition." A better explanation is that the everyday technical knowledge of one era is not the same as that of another. The task of the historian is to try and understand matters within their own context, not dismiss them in the light of what followed.

Claudius Ptolemy, a great scientist of the second century AD, produced a cosmological model that lasted over fifteen hundred years - not because people were too stupid to see it was wrong, but because finding a better theory was incredibly difficult. Maybe today's fundamental physicists are in a similar dilemma. They may not have advanced much in the last thirty years, but I'm sure they'll get somewhere in the next thousand.

Sarah Stewart Johnson, The Sirens of Mars (Literary Review)

When Sarah Stewart Johnson was eleven years old, her father took her to the medical laboratory where he worked, and showed her a 141-year old toenail. It came from one of America's less well-known presidents, Zachary Taylor, who'd been exhumed so that his untimely death could be investigated. Johnson saw the sophisticated machines whose chemical analysis would determine if the unfortunate president had, as rumoured, been poisoned. In fact he wasn't; but for Johnson it was an unwitting foretaste of her own future career. "Although I could sense the enormous power of these instruments, I had no inkling then of their potential as tools for space science." Professor Johnson is part of the science team monitoring NASA's Curiosity Mars Rover; a car-sized buggy that has been trundling across the planet since 2012. After reading her fascinating, elegantly written book on the red planet, I'm glad she didn't become a chiropodist instead.

Johnson begins with the first telescopic glimpses of Mars, from Galileo's "poppy seed" sized view to Schiaparelli's observation in the 1870s of threadlike lines speculated to be canals made by an advanced civilisation. Sceptics said they were an illusion: one astronomer made patterns of random spots and got schoolboys to view and sketch them from a distance. The ones who could see least distinctly tended to merge spots into lines. The evidence was ignored, the truth only emerging in the 1960s when a series of Mars probes flew close enough to reveal the planet's barren surface. "It took only eight days for Mariner 6 and 7 to kill the linear features. The schoolboys had been right. For all that time, the lines we'd seen simply weren't there."

Martian life, if it existed at all, was most likely microbial, perhaps present only beneath the surface. As early as the 1950s, a scientist named Wolf Vishniac had been designing detectors for possible use in a future lander. The "Wolf trap" would scoop soil and deposit it in nutrient-rich water, seeking changes induced by organic processes. In the 1960s Vishniac and his colleague Carl Sagan lobbied for a life-detecting experiment to be included in the forthcoming Viking mission, planned to be launched in 1975, but they met with opposition. Why look for something that most probably wasn't there, when other more useful instruments could be included instead in the craft's limited space? Sagan was even sabotaged behind his back by his former thesis advisor, who judged his research "oftentimes quite useless", complaining that he "dashed all over the field of the planets—life, origin of life, atmospheres, all sorts of things." Sagan would ultimately have the last laugh, becoming one of America's most famous scientists and a major celebrity through his Cosmos television series.

Vishniac was less fortunate, for although a suite of biology experiments was indeed included in Viking, his was squeezed out by budget cuts. Devastated, he went to Antarctica to see if organisms could survive there, then disappeared while collecting samples. He was found dead at the base of an ice slope. Three years later, Viking failed to detect microbes on Mars; but in the same year, Vishniac's rocks were discovered to contain microscopic algae. Perhaps Viking had been looking for the wrong kind of life.

A meteorite thought to originate from Mars caused huge excitement in 1996, containing structures resembling microscopic fossilised worms - though like the illusory canals they were a false hope. Johnson was a teenager at the time, and soon afterwards began studying planetary science at university. Interning at a cavernous experimental facility she had an unnerving experience. "I tasted blood in my mouth. When I reached for my gums, the guide I was with laughed, explaining that there was Martian dust simulant all over the ground, coating the walls like brick flour. It wasn't blood I was tasting, just the sick-sweet tinge of iron hanging in the air."

The real Mars is hostile in other ways. A 2008 lander found large quantities of a toxic salt, perchlorate, that could be a potential hazard for future human visitors. Viking had analysed soil samples by heating, inadvertently releasing gas that would have destroyed organic material. As Johnson says, they'd "been dry-cleaning the samples." Another lander found jarosite, a mineral formed in highly acidic conditions, suggesting that lakes formerly present on Mars may have resembled industrial sludge pools. At best they might have been like the Dead Sea, laden with sodium chloride - a chemical whose value as a food preservative comes from the harm it does to bacteria. "It was the same reason the soy sauce in the JPL cafeteria never spoiled. Soy sauce contains lots of water, yet not enough unbound water for microbes to grow... We'd found water on Mars— the primary goal of the mission— and in the collective excitement, I was slow to realize that not all water gives life. The water on Mars might have been deadly."

Yet all was not lost. In 2013 the Curiosity rover dug its robotic arm into other parts of the planet, finding evidence there for "the right kind of water, in the right kind of place". According to the mission's lead scientist, "you would have been able to drink it." Curiosity is still active: Johnson occasionally gets to drive it. Her book is exhilarating, informative, always engaging and at times beautiful in its lyrical descriptions - Martian dunes are "like egg whites whipped into soft pinnacles". The focus is mainly on NASA's space missions, with little on the various Russian or European Space Agency ones, such as the ill-fated Beagle 2, but that is no serious flaw. If you can't get to Mars then this may be the next best thing.

Sean B. Carroll, A Series of Fortunate Events; Jeremy England, Every Life is on Fire (Wall Street Journal)

When you're feeling small and insecure, just remember how unlikely is your birth. That's the advice in Monty Python's The Meaning of Life, and it's the premise of Sean B. Carroll's entertaining examination of the chain of accidents that have led from dinosaur extinction to our existence today. Going even further back, we could wonder how life itself ever came into being, and that's what Jeremy England tackles in a book that is also rewarding, yet stands in marked contrast.

What both authors agree on is that life has evolved through natural selection. Where they differ is in what it all means. "It really doesn't look like anyone is in charge of human affairs, watching out for us," says Mr Carroll; in which case, "make the most of it... and for God's sake, laugh." Mr England's inspiration, on the other hand, is not Monty Python but the Hebrew Bible. The signs given to Moses, he claims, "can be read as a comment about the border between life and non-life."

Mr Carroll is an evolutionary biologist, well equipped to explain how the random flip of genetic material has, over time, given rise to new forms of life. Mr England is a physicist, seeking to understand how some kinds of matter can have the mysterious property of being alive. The authors' contrasting concerns and temperaments are evident in their writing styles. A Series of Fortunate Events is breezy, anecdotal, informative and amusing. Every Life is on Fire is dense, impassioned and absorbing. The common theme is chance.

A Series of Fortunate Events begins with the golfing prowess of Kim Jong-Il, the former North Korean leader, who supposedly scored five holes-in-one during his very first game. "We do not need any sophisticated understanding of probability, statistics or the game of golf to doubt the veracity of the Dear Leader's scorecard," writes Mr Carroll. What about the long run of black numbers that came up on a Monte Carlo roulette wheel in 1913? If the ball kept landing on black it was surely a good bet, players thought as they staked ever greater piles of chips - losing everything when, after twenty-six blacks in a row, the ball hit red. It's the most famous illustration of what statisticians call the gambler's fallacy. The probability of black remained ½ each time, regardless of how many had gone before.

The odds of dinosaur extinction are harder to quantify. The falling asteroid assumed responsible for their demise was "perhaps a 1 in 500 million years (or longer) event." Rather than fall on our spinning globe's deep ocean, the cosmic roulette ball happened to hit a location that maximised the disaster. "Just 30 minutes either way and the dinosaurs would probably be here."

Progressing through the eons, improbabilities continue to mount. The slow creep of Earth's continents resulted in sudden climatic lurches, whose graph prompts Mr Carroll to remark, "holy #$%!, that's a lot of large swings... What sort of animals could adapt?" The answer: "go look in the mirror." Evolution itself is propelled by random DNA mutations that Mr Carroll likens to misprints, allowing him to introduce further asides such as the notorious 1631 Bible that mistakenly ordered, "Thou shalt commit adultery." Mutations are far rarer than typos: we all have only a few dozen among the billions of base pairs making up our DNA, and most have no effect, good or bad. Natural selection works because it has so many base pairs and generations to play with, "like an amateur golfer who, given enough swings, will eventually hit the target."

The evolution of humans is, of course, still a long way from the creation of you. Had just one of your ancestors failed to produce offspring, you would never have appeared. Closer to home, "it's time to think about your parents' gonads, and the moment you were conceived." At which point we'll leave Mr Carroll pondering "the accident of all mothers."

Every Life is on Fire takes the enigma of existence much further back. "Every living thing we know of sprang from another living thing, yet we have reason to think that there was no life at all anywhere when the world first got going... Does our existence express the intention of a Creator who made us in his image, or are we - and all other life - merely an exotic variety of frost condensed in the razor-thin layer between ground and sky? Can it be both?" Mr England aims to show how life could have arisen spontaneously through natural processes in a God-given universe. In order to do that, he needs a clear definition of what counts as life.

We could start by saying that a living thing is capable of reproducing itself. But fire does that too - so what's the difference? One is degree of order - fire messes things up in a way that even the worst plague of locusts can't match. This hints at the importance of entropy, which in rough terms is a measure of disorder. Another feature of fire is that it is autocatalytic, producing heat which in turn produces more fire. Living things somehow keep things in check, though like fire they convert forms of energy. A match turns chemical energy into flame; we convert food into everything we do.

I did say that Mr England is a physicist, and the fact that energy and entropy come into play means that he's specifically concerned with thermodynamics. This was originally a theory of gases and fluids, and properties such as pressure and temperature. In the nineteenth century it was seen how these could be explained as the collective motion of countless constituent particles, giving rise to a theory called statistical mechanics. That takes us back to the vagaries of chance - not asteroids and genes now, but the random swerve of molecules. When randomness starts to look ordered, are we seeing signs of life? Again no - think for instance of a snowflake. But particle statistics are a way of understanding energy and entropy, and hence perhaps the boundary between life and non-life.

Less familiar than snowflakes, though almost as pretty, are the mosaic-like patterns that can sometimes form on warm liquid surfaces, known as Bénard cells. Like a living organism, these swirling patches constantly absorb energy (heat from below), convert it into another form (movement), yet maintain an orderly appearance. It looks like a kind of equilibrium - which is how in a calm moment you might imagine yourself to be. In reality, given the constant through-put of energy, the Bénard cells are far from thermodynamic equilibrium, and the same is true of any living organism. All of them, in physics terms, are "dissipative systems".

So far, so standard. Erwin Schrödinger, in a book called What Is Life?, long ago appreciated that organisms utilise energy in a way that increases order and therefore lowers local entropy, without violating the famed second law of thermodynamics that says the entropy of the universe as a whole cannot decrease. Mr England's innovation - first aired seven years ago in a paper that generated much interest and controversy - is what he terms "dissipative adaptation". He envisages chemical systems that would not only possess the reproductive power of fire and the self-organising characteristics of Bénard cells, but would also produce copies - offspring, so to speak - whose mutations could be subject to a kind of natural selection, driven by efficiency at utilising energy. Can such systems be made in a lab? That's what Mr England and his colleagues are working on.

Don't expect Frankenstein's monster - something that comes close to realising Mr England's speculative idea is an experiment involving plastic particles in viscous fluid getting blasted by sound waves. The trouble with dissipative adaptation is that it seems to take us rather far from the living things whose origin it's meant to explain. The spiritual dimension also falls by the wayside, though thankfully gets taken up at the end of what is frankly a difficult, though potentially very important book. Unlike A Series of Fortunate Events - which is exquisitely adapted to a familiar niche in the popular science ecosystem - Every Life is on Fire comes to us from the forefront of scientific enquiry; a novel species whose fate remains to be seen.