Big Book is not key to universe

The word "reality" in the title of this book lies at the heart of this text's problem. Brian Greene is in essence comparing his physics of today - physics supposedly replete with elemental particles, super-symmetry, strings, quantum mechanics, curved space, gravitons, vacuum energy and general relativity - with the dawn of physics in the age of Isaac Newton. When, however, Newton was writing the Principia in the 1680s, physics was tangible and "real". Newton talked about objects and concepts that could be experienced. Real apples fell from real trees. A visible moon orbited a solid earth. The forces exerted by the moon actually moved the waters and caused the ebb and flow of the tides. Solid glass prisms broke light into colours that could be seen.

Newtonian pushes and pulls and accelerations and constant velocities were commonplace experiences of everyday life. Clocks ticked monotonously, time advanced and things aged. Space behaved itself and there were only three dimensions: up, across and along. There was no uncertainty principle. In Newton's time, you not only knew where you were, you also knew how fast you were going. And the universe was perceived to be infinite in extent and static, simply because if it were not, it would fall in on itself. Newton did not need to know about atoms or ten-dimensional space to make great strides in understanding force, mass, motion and gravity.

Everything has apparently changed for Greene's physicist at today's frontiers. Certainty and reality have retreated into the distance. Our cosmology now relies on an inflation-ridden Big Bang that occurred some 14 billion years ago. We grasp at tiny temperature differences in the cosmic background radiation to hint at the seeds of galaxy formation and quantum fluctuations. The fact that the modern cosmology has more in common with the first chapter of Genesis than with normal evolutionary science is overlooked. We are assured that the galaxies are not moving apart, it is just the fabric of space between them that is swelling. A vacuum is not empty. Solid familiarity is replaced by a mass balance that has 70 per cent of what is supposedly there (and here) actually in the form of dark energy, and 25 per cent in the form of dark matter. Everyday units, where volumes are measured in terms of the space occupied by a London bus, lengths in terms of the height of Nelson's Column and time in terms of our allotted three score years and ten are replaced by the inconceivably small. The Planck length of 10-33cm, the Planck area (about (10-33)2cm2) on the expanding surface of the universe, and the Planck time of 10-43 seconds are of paramount importance.

Today, we are admonished for appreciating a physical diversity in which gravity might have little to do with magnetism, and heat might possibly be independent of sound. Present-day physicists have apparently failed if they cannot "unify" everything. Quantum mechanics, which has revolutionised our understanding of small things such as atoms and their constituents, and general relativity, which has revealed much about big things such as stars, galaxies and clusters of galaxies, have to be shoehorned into a common unified theory.

Greene writes with frenetic enthusiasm. We are regaled with single-word sentences such as "Wow". We are entreated to "break free from the spatio-temporal chains with which we have been shackled for millennia". We are informed that "space and time capture the imagination like no other scientific subject". Do they? This statement is supposedly so self-evident that even in a book of this length, little is posited in justification. We are led away from the thousands of laboratory physicists tackling the realistic problems of our surroundings and we are instructed that "to open our eyes to the true nature of the universe has always been one of physics' primary purposes". Greene insists that the distinction between past, present and future is an illusion, that today "our understanding of reality's arena has been completely transformed". String theory should clearly be the answer to our prayers.

Greene turns his back on the fact that today's physicist has a reasonable understanding of the middle ground. He eagerly rushes past the proton and the neutron towards ever smaller things, where our understanding becomes progressively more hazy. Greene encourages us to move out and back. The edge of our universe, its mysterious beginning and its as-yet-unfathomable end are the preferred destinations. He tries very hard to convince his reader that solutions in these areas are just around the corner. We are apparently hovering on the brink. Just a few more spacecraft, each adding slightly more precision to our measurements of the temperature and polarisation of the cosmic background radiation might just do it. And if the Large Hadron Collider does not solve the problems of matter and gravity when it starts working in 2007, Greene suggests that there is every possibility that a Very Large Hadron Collider or an Extremely Large Hadron Collider will do the trick in a few decades' time.

The Fabric of the Cosmos does not convince me. Even though Greene is very gung-ho, always looking on the bright side and deftly playing down doubts and uncertainties, I came away feeling that there is a strong possibility that the solutions to the physical problems of the very small and very large and the distant past and equally distant future might easily be as far away from us now as Isaac Newton is in the past. This book left me with a poetic Walt Whitman feeling:

" When the proofs, the figures, were ranged in columns before me, / When I was shown the charts and diagrams, to add, divide, and measure them, / How soon unaccountable I became tired... ".

To me the joy of physics lies in the realisation that the world we experience can probably be understood. When we venture way beyond our environment, the balance between the known and the unknown shifts ominously. Maybe a complete understanding is extremely distant, if not unattainable. Modern physics is a subject of many mysteries. A new equally unfathomable one has been added. Why did this book need to be 569 pages long? I did reach the end but, oh, what an uphill and unrewarding task it was.

David Hughes is professor of astronomy, Sheffield University.