Nothing is gained by searching for the 'theory of everything'.

By Robert Matthews. Reproduced by kind permission of the author.

They call their leader The Pope, insist theirs is the only path to enlightenment and attract a steady stream of young acolytes to their cause. A crackpot religious cult? No, something far scarier: a scientific community that has completely lost touch with reality and is robbing us of some of our most brilliant minds.

Yet if you listened to its cheerleaders - or read one of their best-selling books or watched their television mini-series - you, too, might fall under their spell. You, too, might come to believe they really are close to revealing the ultimate universal truths, in the form of a set of equations describing the cosmos and everything in it. Or, as they modestly put it, a "theory of everything".

This is not a truth universally acknowledged. For years there has been concern within the rest of the scientific community that the quest for the theory of everything is an exercise in self-delusion. This is based on the simple fact that, in spite of decades of effort, the quest has failed to produce a single testable prediction, let alone one that has been confirmed.

For many scientists, that makes the whole enterprise worse than a theory that proves to be wrong. It puts it in the worst category of scientific theories, identified by the Nobel Prize-winning physicist Wolfgang Pauli: it is not even wrong. By failing to make any predictions, it is impossible to tell if it is a turkey, let alone a triumph.

It is this loss of contact with reality that has prompted so much concern among scientists - at least, those who are not intimidated by all the talk of multi-dimensional superstrings and Calabi-Yau manifolds that goes with the territory. But now one of them has decided the outside world should be told about this scientific charade. As a mathematician at Columbia University, Peter Woit has followed the quest for the theory of everything for more than 20 years. In his new book Not Even Wrong he charts how a once-promising approach to the deepest mysteries in science has mutated into something worryingly close to a religious cult.

It began in the mid-1980s, with the emergence of so-called superstring theory, according to which all the particles and forces in the universe are linked to vibrations of tiny, multi-dimensional, string-like entities possessing something called supersymmetry (do not ask). By unifying so much so neatly, superstring theory seemed to be a glimpse of the theory of everything that had eluded even Einstein himself. Many of the world's smartest theoreticians joined the effort to understand superstrings, including several Nobel Prize winners.

But they soon ran into trouble. The mathematical elegance of superstring theory collapsed under a mass of messy facts about the real universe. Worse still, hopes that it would lead to a unique theory of everything evaporated, with ever more versions emerging and no obvious way of deciding between them.

By the mid-1990s, superstring theory had been subsumed into something called M-theory. Not even its inventor - the charismatic Edward Witten of the Institute for Advanced Study in Princeton - knows what the M stands for. Nor has he, or anyone else, succeeded in persuading M-theory to make a single testable prediction. As such, it has more in common with a religious conviction than science.

Most theorists pay at least lip-service to falsifiability, popularised by the philosopher Karl Popper, according to which scientific ideas must open themselves up to being proved wrong. Yet those involved in the quest for the theory of everything believe themselves immune from such crass demands. Mr Woit quotes a superstring theorist dismissing the demand for falsifiability as "pontification by the 'Popperazi' about what is and what is not science".

Coming from a community that refers to Prof Witten as The Pope this is a bit rich. But it also suggests the whole field is now propped up solely by faith. Mr Woit provides plenty of evidence for this: the insistence of M-theorists that in the quest for ultimate answers, theirs is "the only game in town"; the lectures with titles such as The Power and the Glory of String Theory; the cultivation of the media to ensure wide-eyed coverage of every supposed "revelation".

Mr Woit has shown that some very smart people in academia have lost the plot. But why should the rest of us care? The reason is simple: the quest for the theory of everything has soaked up vast amounts of intellectual effort and resources at a time when they are desperately needed elsewhere. We can ill afford to let more brilliant talent vanish into the morass that is M-theory.

Those who have show signs of having fallen prey to the "sunk-cost fallacy", the huge intellectual effort needed to enter the field compelling them to plough on regardless of the prospects of success. It is time they were put out of their misery by being told to either give up or find funding from elsewhere (charities supporting faith-based pursuits have been suggested as one alternative).

Academic institutions find it hard enough to fund fields with records of solid achievement. After 20-odd years, they are surely justified in pulling the plug on one that has disappeared up its Calabi-Yau manifold.

The writer is visiting reader in science at Aston University, Birmingham.