Stephen Hawking’s inaugural lecture as Lucasian Professor of Mathematics at Cambridge University in 1980 caused quite a stir. Its title – “Is the end in sight for theoretical physics?” – raised the prospect of a unified “theory of everything”. Hawking suggested that there was a good chance of resolving the remaining inconsistencies between the two big “theories of something” – quantum mechanics and general relativity – before the turn of the century.

My first impression on reading The New Physics for the Twenty-First Century, a collection of essays edited by science journalist Gordon Fraser, is that a theory of everything may still be attainable by the turn of the century. However, there is now 20 times more of everything in the universe than there was in the past century, 95% of which no-one has ever actually seen, or had even heard of until a few years ago – as summarized in articles by Wendy Freedman, Edward Kolb and Ronald Adler. Despite this, Michael Green describes amazing developments in string theory that could tie everything together, if one could just figure out which, if any, of the apparently infinite varieties of string theory applies to our world, and why.

The New Physics for the Twenty-First Century is the successor to The New Physics, edited by Paul Davies and published in 1989, which is still in print and well worth a read. Despite the cosmological conundrums painfully laid out in the new book, there is much good news in it for those of us still working on the 5% of everything that we can see. Since 1989 there has been a renewed and productive emphasis on uncovering the secrets of familiar systems in the domain of atomic, molecular and optical physics, and condensed matter viewed on the nanometre scale.

The signature themes of this modern research are quantum information and nanotechnology, represented by seven of the 19 articles in the new book, compared with four of 18 in the previous book. This shift reflects new tools for observation and control of nano-scale systems that have been developed over the past two decades, such as scanning-probe microscopy and laser cooling and trapping.

As for specific points of comparison, the two books have no editors or authors in common but both groups are eminent. The new book contains two articles co-authored by Nobel laureates, Claude Cohen-Tannoudji and William Phillips, and many others by acknowledged leaders of research fields, such as Artur Ekert, Anton Zeilinger and Yoseph Imry. A wide range of styles of presentation is displayed in the two books, ranging from Malcolm Longair’s extraordinary 105-page review of astrophysics in the 1989 book (containing material comparable to an academic review paper) to Henry Hall’s account of superfluids in the new book, which combines scientific erudition with poignant personal memoirs of key participants.

My impression is that the new book is more accessible to a general readership. To some extent this is down to the freshness of the technical material, but it also presents topics that can be usefully pondered by those with little background in physics – for example the articles on e-science, by Tony Hey and Ann Trefethen, and physics and society, by Ugo Amaldi. It gives one pause to think that when The New Physics was published in 1989 the arXiv.org preprint repository was unknown, but today it is one of the main vehicles of communication in physics and its mode of presentation has transformed scientific publishing. Amaldi’s article also evokes unpleasant memories of a period of notorious fraud in physics publications just a few years ago. I have yet to understand what motivates physics fraudsters since they seem certain to be exposed, as they were in these cases by the ordinary functioning of the peer-review process. Yet Amaldi’s essay raises interesting points about the social dynamics of scientific fraud.

The two books are well worth perusing in parallel. But to conclude with comments on the current book alone, it is written at a level that can be digested by eager undergraduates but will also be instructive to experienced physicists. It is lavishly produced and good value – several physicist colleagues have passed on unsolicited praise of the level of presentation. I also tried it out on an eminent retired chemist, who first learned physics as a canonical recitation of established facts. “Things sure have changed,” he said.

Indeed they have. Physics has accomplished much in 400 years, solving some of the hardest problems while revealing even harder ones. The message of The New Physics for the Twenty-first Century is that the most fundamental problems remain elusive, but the magnificent tools that have been developed during the past decade have opened up new vistas on subjects once thought to be familiar.

What’s in and what’s out

It is easy to obtain the 100 most common non-trivial words used in any book simply by going to amazon.com. This means you can compile a list of words that appear often in The New Physics for the Twenty-First Century but not in its predecessor.
What’s in: laser, molecule, membranes, string, neutrino, materials, information, standard, measurement, gravity
What’s out: proton, neutron, charge, colour, galaxies, strong, hole, equation, length, gravitational