The discovery of the neutron and the concurrent work on the structure of the atomic nucleus are among the high-water marks of British physics in the 20th century and, in Brian Cathcart's book at least, a classic triumph of clearsighted determination, ingenuity and skill over the limitations of cold, cramped and bleak Cambridge laboratories, ramshackle equipment and eternally inadequate funding.
That the work was driven in large measure by the towering presence of New Zealander Ernest Rutherford (dubbed "the battleship of physics") is far from overlooked, for the book begins with Rutherford gathering his pioneering team about him - James Chadwick, Ernest Walton and John Cockcroft - and presiding over their work with eccentric indulgence.
And if Rutherford offers a sort of paternal inspiration (and an overwhelming conviction that his picture of the nuclear atom is the right one) to his more youthful co-workers, the other giants of the age are seldom far from view: Planck and Schrödinger, Bohr, Heisenberg and Pauli are formulating the tenets of quantum mechanics, and Einstein too is close at hand through his ever-useful equation for the transmutation of matter into energy.
Apart from the odd daft simile and occasional descent into schoolboy humour ("It was as if the nucleus, hitherto so secret and silent, had crept up behind them and shouted 'Boo!'") this is a stimulating reconstruction of the short but astonishing period that produced three Nobel laureates: James Chadwick, remorselessly tracking down the neutron; and John Douglas Cockcroft and Ernest Walton transmuting a range of low-atomic weight targets by bombarding them with high-voltage proton beams - or, to use the jargon of the period, "to split the atom".
Several generations later, both of humans and sub-nuclear particles, Cathcart has revived the excitment and though Cathcart is not himself a scientist, he recreates the atmosphere of Cambridge between the wars with great skill: he invokes the spirit not only of the physicists working away with their scintillation counters in the Cavendish, but of Kim Philby and his coterie of Cambridge spies, and prefigures the work of James Watson and Francis Crick on the structure of DNA elsewhere in Cambridge half a generation later. (You can almost hear Fred Hoyle and Martin Ryle locked in spirited dispute about the nature of the universe.) What does the title of the book mean? It's the phrase Rutherford himself coined to describe the size of the nucleus inside the entire atom - and more immediately useful, for this reviewer at least, than any number of orange and basketball representations of the atom (or the solar system, if it comes to that).
