Tuesday, 27 March 2012

How It Began

How It Began: A Time-Traveller's Guide to the Universe by Chris Impey

Wall Street Journal, 28 March 2012

'The theory is beautiful beyond comparison" is how Albert Einstein modestly described his theory of gravity, known as general relativity. He believed that "scarcely anyone who fully understands this theory can escape its magic." In the years since 1916, when he published a paper setting out the theory, few have disagreed, yet buried within his greatest achievement was also what Einstein considered "my greatest blunder."

The equations of general relativity can be solved in a number of different ways, with each solution representing a model of a possible universe. Like everyone else at the time, Einstein believed that the universe was eternal and unchanging, so he incorporated a mathematical term, the "cosmological constant," to ensure that that was exactly how it remained. This fixing of the equations was Einstein's great blunder, for he failed to grasp the full magic of his theory. It was left to others to take seriously the solutions that pointed to a universe that was not static but expanding.

In his previous book, "How it Ends" (2010), Chris Impey, a professor of astronomy at the University of Arizona in Tucson, outlined the ultimate fate of our expanding universe. It was a somber scenario in which galaxies sail apart at an ever-increasing rate as the stars within them fade to dark embers, with the structure of the universe eventually unraveling.

In his latest book he tackles the more difficult question of how the universe began. In clear, enthusiastic and occasionally lyrical prose, Mr. Impey takes the reader on a mind-blowing tour back through eons, stopping along the way to explain the formation of the solar system, the birth and death of stars, white dwarfs, supernovas, spiral galaxies, cosmic inflation, string theory, black holes and M-theory—an extension of string theory featuring 11 space-time dimensions that can be curled up into the four we're familiar with in 10500 (1 followed by 500 zeros) ways. Each such solution leads to another potential universe, but ours is the one that interests Mr. Impey.

 Georges Lemaître

It was the Russian mathematician Alexander Friedmann who, in 1922, first showed that general relativity predicted an expanding universe. But Mr. Impey rightly chooses to highlight the work of Georges Lemaître, a Belgian priest who was also a physicist. In 1927 Lemaître realized that "running the clock backwards" on an expanding universe led to one that was smaller, denser and hotter in the past. "The fireworks are over and just the smoke is left," he said of the quest to imagine the initial state of the universe. "Cosmology must try to picture the splendor of the fireworks." Lemaître eventually arrived at a model that he called the "primeval atom" and that we call the Big Bang.

When Lemaître discussed the idea with Einstein, he was unimpressed. "Your math is correct, but your physics is abominable," he told Lemaître. Yet six years later, in 1933, Einstein heard Lemaître lecture and afterward admitted it was "the most beautiful and satisfactory explanation of creation I've ever heard."

The reason Einstein changed his mind was that by the late 1920s the American astronomer Edwin Hubble had discovered two remarkable facts. The first was that what we had long assumed to be the universe was only our host galaxy, the Milky Way, which in turn was just one of many such "island universes." Second, Hubble found that light from these distant galaxies was stretched toward the red end of the visible spectrum. This so-called redshift is evidence that these galaxies are moving away from our own and that the universe, therefore, is expanding. This supported Lemaître's theory that if the expansion could be rewound, the universe would steadily contract and eventually reach what he called "a day without yesterday."

According to the Big Bang model that has grown from Lemaître's insight, the moment of instantaneous creation was 13.75 billion years ago and began with a singularity, a point of infinite mass and density where our present understanding of physics simply breaks down. Yet "the Big Bang is all around us," Mr. Impey notes, in the form of cosmic microwave background radiation, which suffuses the entire universe. Soon after it was discovered in 1964, scientists recognized this radiation as the echo of the Big Bang, an afterglow from the era when the universe was hotter and denser. "There are tens of thousands of microwaves from creation in every breath you take," Mr. Impey delights in revealing.

It had long been assumed that gravity would act as a brake on cosmic expansion, but astronomers were horrified to discover in the 1990s that the expansion is speeding up. "Dark energy" is the mysterious culprit, but the name is more of a sign of ignorance than a physical description of something that makes up approximately 73% of the mass-energy of the universe. If that wasn't surprising enough, an analysis of the motion of galaxies reveals that approximately 23% of the universe is made up of something dubbed "dark matter." This means we know nothing about roughly 96% of our universe.

The Big Bang model also says nothing about what banged, why it banged or what happened before it banged. So in the 1990s cosmologists began to take seriously the idea that our universe is but part of a "multiverse" of different universes, each with its own laws of physics. It's a step too far for Mr. Impey, who suggests that "with the multiverse we seem to have taken leave of our senses and entered into wild speculation." There are some excellent books on this new multiverse cosmology, such as John Barrow's "The Book of Universes" and Brian Greene's "Hidden Reality," but "How It Began" deserves to be a well-thumbed guidebook for—and in—this universe.

Monday, 26 March 2012

Turing's Cathedral

Turing's Cathedral:The origins of the Digital Universe by George Dyson
Daily Telegraph, 24 March 2012
"Princeton is a madhouse,” wrote Robert Oppenheimer in January 1935. Twelve years later, after directing the building of the atom bomb, he would return to the Institute for Advanced Study (IAS) to take charge of this “madhouse”.

One of the permanent residents was Einstein. Another of Oppenheimer’s new charges was a former colleague from the Manhattan Project who was now “thinking about something much more important than bombs”.

The Hungarian-born polymath John von Neumann would make seminal contributions to everything from quantum mechanics to game theory, and had turned his prodigious talent to “thinking about computers”.

On November 12 1945, he gathered together six people and started the IAS’s Electronic Computer Project to design and construct a programmable electronic digital computer. After five years the Mathematical and Numerical Integrator and Computer (Maniac) was fully functioning but it had only five kilobytes of storage, less memory than is used to display a single icon on your computer screen.

The rest may be history but it’s one George Dyson is uniquely qualified to capture in Turing’s Cathedral. The son of the distinguished physicist Freeman Dyson, he grew up in the environs of the IAS where his father has been a member since 1948. Dyson used his privileged position to gain access to people and to explore archives untouched for decades. The years of research and writing have enabled him to bring to life a myriad cast of extraordinary characters each of whom contributed to ushering in today’s digital age.

While our universe may have popped out of nothing due to what physicists describe as a quantum fluctuation, the origins of the digital universe of 0s and 1s required the US military’s desire to be armed with a hydrogen bomb at the beginning of the Cold War and it “had to be squeezed into existence” between simulations of nuclear explosions. Two real-world explosions in 1952 and 1954 confirmed the correctness of those calculations and the indispensable nature of a computer that could be reprogrammed to carry out different tasks, the theory behind which had first been worked out by the British mathematician Alan Turing.

Alan Turing
Despite its title, Turing doesn’t make his much anticipated entrance in Dyson’s book until chapter 13, when as a 24-year-old he boards a transatlantic liner bound for New York in September 1936. Turing was to spend the next two years in Princeton working on his PhD, but before leaving Britain he had already finished his seminal paper “On computable numbers”. It would, as Dyson points out, “lead the way from logic to machines” as Von Neumann’s team turned Turing’s theoretical ideas into Maniac. 

Turing may have been the intellectual visionary, but Dyson’s book is about Von Neumann, the chief architect who oversaw the construction of the hardware and software architecture that allowed sequences of code to be stored, recalled and executed. Yet Dyson acknowledges that Maniac was not the first operational stored-programme computer. That was the Small Scale Experimental Machine, developed in June 1948 at Manchester University where Turing was by then based having helped break the German navy’s Enigma code during the war as a leading member of Bletchley Park.

Turing and Von Neumann were chalk and cheese in everything except their shared interest in computers. Von Neumann always dressed in a suit and spoke with precision; Turing was unkempt and hesitated as if words could not keep up with his thoughts. Von Neumann had an eye for women; Turing’s homosexuality would lead to a conviction for gross indecency. Forced to undergo “therapy” with oestrogen injections, he committed suicide in 1954.

Faced with the tricky task of balancing technical details with keeping the narrative accessible for the non-computer buff, Dyson ends up probably not giving enough detail to satisfy the aficionado but too much for the lay reader. “Evolution in the digital universe now drives evolution in our universe,” he says, “rather than the other way around.”

Turing, Von Neumann and their colleagues may have let the genie out of the bottle, but Dyson has done the difficult job of reminding us of how much we owe them and how far we have come in such a short time.

Saturday, 17 March 2012

About Time

About Time: From Sun Dials to Quantum Clocks, how the Cosmos Shapes Our Lives by Adam Frank

Daily Telegraph, 17 March 2012

St Augustine, the fifth century theologian and Church father, famously discussed the nature of time in Book XI of his Confessions: ‘What is by now evident and clear is that neither future nor past exists, and it is inexact language to speak of three times – past, present, and future. Perhaps it would be exact to say: there are three times, a present of things past, a present of things present, a present of things to come.’ For centuries it was a description as good as any.

Today there are many books on the nature of time as we experience it and even more on cosmic time as revealed by science. Yet few attempt to recount the entwined narratives of cosmic history and human time as a unified whole. Adam Frank’s About Time does just that. An astrophysicist at the University of Rochester, he and many of his colleagues believe that ‘the Big Bang is all but dead’. 

Frank and the others do not doubt the scientific narrative of cosmic evolution over the last 13.7 billion years, only the ‘bang’ in Big Bang. The moment of creation with no before is being questioned because of the very precision of the science that gave the notion ‘a measure of reality in the first place’. ‘The roots of cosmology cannot be reworked without a new conception of time, including its origins and its physical nature,’ argues Frank in this excellent book.

Cultures have always needed a cosmology to understand their place in the framework of creation. Frank shows how, as our ideas about cosmology and cosmic time have changed, human time has also changed. Acknowledging that the broad sweep of history, science and time which follows focuses primarily on the cultural development associated with the West, for Frank the most potent and obvious example of the binding of human and cosmic time is the industrial revolution with its roots in the scientific discoveries of Newton and its radical reformation of everyday life.

The first intimation of the modern structured day was born in the medieval monasteries. From sunrise to sunrise, the monks followed the horae canonicae, the rounds of worship beginning from sunrise (matins) through midday (sext) and sunset (compline) and through the night to matins again. 

Yet the division of the day into 24 hours was an invented by Babylonian astronomers, but it did not gain widespread acceptance until the advent of mechanical clocks in the 14th century. No one knows who invented the clock and in particular its key component – the escapement, the notched metal rings that allow gravitational energy stored in a hanging weight to be regulated and regularly released.

Prague's famous town clock
By the end of the 15th century, the town clock was a matter of civic need and pride. Soon the ancients’ Earth-centre universe gave way to Copernicus’s sun-centred cosmos and then to Newton’s clockwork universe, with space and time as absolute, unchanging and eternal. 

Throughout 18th century the new universal laws of physics reworked human conceptions of the heavens and before long led to machines that paved the way to industrialisation. And today we describe times in digital format – for example, 1.17 p.m. ‘It’s a new time that we have created in our hyperdigital, telepresent, instant-messaged society,’ says Frank. 

After 50 years of trying, physicists still lack a theory of quantum gravity – ‘a theory of space and time on scales so small entire universes could be bound in an atom’. Consequently cosmology, and our understanding of time, remains incomplete and full of speculation. Is the universe one in a long line? Could there be many bangs going off all the time, creating simultaneously existing universes – a multiverse? These ideas might sound like science fiction but they are being seriously pursued by some theorists while others, reports Frank, hope for ‘something else, something better, something not yet imagined’.

Monday, 12 March 2012

A Universe From Nothing

A Universe from Nothing: Why There is Something Rather than Nothing, by Lawrence M. Krauss.

Financial Times, 10-11 March 2012

Why is there something rather than nothing? “While this is usually framed as a philosophical or religious question,” writes Lawrence Krauss in A Universe from Nothing, “it is first and foremost a question about the natural world, and so the appropriate place to try and resolve it, first and foremost, is with science.”

A leading physicist at Arizona State University, Krauss begins his entertaining and engaging introduction to cosmology by pointing out that when scientists ask “why?” they usually mean “how?” So for “Why is the Earth 93m miles from the Sun?” read “How is the Earth 93m miles from the Sun?” What we need to understand are the physical processes that led to the Earth ending up in its present position.

“Nothing expands the mind like the expanding universe,” says Richard Dawkins in an afterword to this book. It was the American astronomer Edwin Hubble who, in the 1920s, discovered the first evidence that we lived in an expanding universe. As Krauss makes clear, the weight of the accumulated observational data since points to a Big Bang some 13.75bn years ago.

There have been a number of fine cosmology books published recently, but few have gone so far, and none so eloquently, in exploring why it is unnecessary to invoke God to light the blue touchpaper and set the universe in motion.

An instant after the Big Bang, the cosmos was smaller than an atom. It is here that the best theory physicists have for understanding the science at this atomic level comes into play: quantum mechanics. Often counter-intuitively, this describes an atomic reality where “virtual” particles can pop in and out of existence in a time so short they cannot be seen but only inferred from circumstantial evidence.

Lawrence Krauss
“At the heart of quantum mechanics is a rule that sometimes governs politicians or CEOs – as long as no one is watching, anything goes,” explains Krauss. Given the size of the baby universe after the Big Bang, quantum mechanics suggests it is possible that space and time, like virtual particles, just pop out of nothing because “nothing” is an unstable state. This is a concept of “nothing” far removed from the ordinary usage of the word: in quantum physics it is full of potential and possibilities, always poised on the verge of something.

So why does the universe exist? “Ultimately,” Krauss admits, “this question may be no more significant or profound than asking why some flowers are red and some are blue.” Nevertheless, I am glad that there are scientists like him who will tackle it all the same. 

Wednesday, 7 March 2012

Higgs Force

Higgs Force: The Symmetry-Breaking Force that Makes the World an Interesting Place by Nicholas Mee

Literary Review, March 2012

Last December, with the Internet having been awash with rumours for weeks, saw the official announcement of the latest results in the search for the Higgs particle from the fellowship of the ring – the physicists working at CERN’s 27km circular Large Hadron Collider (LHC). The Higgs is the missing piece of the theory that describes the behaviour of fundamental particles and the forces that act between them. It plays a special role in giving all the other particles mass.

The teams running the two giant detectors at the LHC independently put the mass of the Higgs, which is measured in what physicists call gigaelectron volts (GeV), somewhere between 116–130 and 115–127 GeV respectively. Although the scope of the search for the Higgs has now been narrowed, particle physicists demand an extraordinary degree of precision in their measurements. As the CERN press release made clear, even a 98 per cent chance of being correct is ‘not yet strong enough to claim a discovery’.

Particle collisions at CERN
If all the data generated by the LHC were stored on CDs it would fill more than a million every second. This is one of the more astonishing facts that Nicholas Mee reports in his book Higgs Force. To overcome this problem detectors are designed to be highly selective about the data passed on for storage. When the LHC smashes beams of particles together there are a billion or so collisions per second within the ATLAS detector alone, yet only the data from a couple of hundred collision events that have the telltale signs of interesting and possibly new physics are recorded.

The system that performs the selection process and determines which information is discarded and which is stored for analysis is called the trigger. Nicholas Mee acts as the trigger as he selects the tales to tell of those whose work has helped reveal the structure of matter and the laws of nature, culminating in the present hunt for the Higgs particle. The result is an intellectual journey that ends at the LHC near Geneva but begins with the Big Bang 13.75 billion years ago.

When the universe was born there was only a single force, which Mee calls the Higgs force. Moments after its birth the temperature began to fall as the universe expanded and the original force was shattered into four disparate pieces. The strong force would hold the quarks together in the atomic nucleus, while the weak force would transmute matter and make the different elements. The electromagnetic force would bind atoms and control their chemical reactions, and then there was gravity. Mee focuses on the three forces that matter when it comes to particle physics – electromagnetism, weak and strong – and attempts the difficult task of trying to explain how physicists have discerned that although ‘the universe began in a perfectly symmetrical state, the Higgs broke this symmetry and enabled the matter that formed within the universe to evolve into complex and diverse structures’. Without the Higgs particle the universe would have remained in a state that was ‘homogeneous, lifeless and uninteresting’.

Most people have an intuitive feel for what symmetry means. They recognise symmetrical patterns when they see them. However, physicists understand symmetry in terms of transformation, such as a reflection in a mirror, a rotation around an axis or a translation through space. An object or a pattern possesses a symmetry if it does not change when it is transformed in some way. For instance, if a snowflake is rotated around its centre by sixty degrees (one sixth of a complete revolution), it will appear exactly the same after the rotation as it did before. In fact all rotations through multiples of sixty degrees are symmetries of a snowflake.

Symmetry has become fundamental to the way that physicists view the universe, and an increased understanding of the symmetries of nature has been one of the major themes in the development of physics. When a quantity remains unchanged throughout a physical encounter it helps physicists to disentangle the details of what might be an extremely complicated event. This is true of the collisions that take place at the LHC. Mee does an admirable job of explaining all this before tackling ‘spontaneous symmetry breaking’, which lies at the heart of the Higgs story.

Peter Higgs
This book is far broader and more accessible than its title may suggest. For instance, we learn that the scientific investigation of magnetism dates back to William Gilbert, the personal physician of Elizabeth I. He was one of the first to try to understand the workings of nature through experimentation rather than philosophical argument. He concluded from his many experiments that the Earth is a magnet, explaining why a compass needle points north. Among others that we meet is a physicist who compared his power to transmute the elements to the mythical alchemist Hermes Trismegistus; an astronomer who was captivated by the beauty of a falling snowflake; the British physicist whose work predicted the existence of antimatter; the theorist who transformed particle physics with his eightfold way; and Peter Higgs, whose long wait for the discovery of the particle that bears his name may soon be over.