Scientists have solved the explainable mysteries of the universe, John Horgan believes. All they can do now is fill in the details and practise their craft 'ironically'.

These are trying times for truth-seekers. Scientists feel increasingly besieged by technophobes, animal rights activists, postmodern philosophers and, most important of all, stingy, know-nothing politicians. After decades of stupendous growth, funding for basic research has begun to decline in the United Kingdom, the United States and other industrialised nations.

Also, as science advances, it keeps imposing limits on its own power. Einstein's theory of special relativity prohibits the transmission of matter or even information at speeds faster than that of light. Quantum mechanics dictates that our knowledge of the microrealm will always be slightly blurred. Chaos theory confirms that even without quantum indeterminacy many phenomena would be impossible to predict, because minute influences can have gigantic consequences. And evolutionary biology keeps reminding us that we are animals, designed by natural selection not for discovering deep truths of nature but for breeding.

All these limits will make the search for truth more difficult in years to come. But in my view, by far the greatest threat to science's future is its past success. To understand what I mean, one must recall just how much science has already accomplished. Researchers have created a kind of map of physical reality, ranging from the microrealm of quarks and electrons to the macrorealm of planets, stars and galaxies. Physicists have shown that all matter is ruled by a few basic forces - gravity, electromagnetism and the strong and weak nuclear forces.

ÖйúAƬ

Scientists have also stitched their knowledge into an impressive, if not terribly detailed, narrative of how we came to be. The universe exploded into existence 15 billion years ago, give or take five billion years, and is still expanding outwards. About 4.5 billion years ago, the detritus from an exploding star, a supernova, condensed into our solar system. Sometime during the next few hundred million years, for reasons that may never be known, single-celled microbes bearing an ingenious molecule called DNA emerged on the earth. These microbes - nothing more than pond scum, really - diversified, by means of natural selection and Mendelian genetics, into an extraordinary array of more complex creatures, including Homo sapiens.

My guess is that this basic narrative that scientists have constructed from their knowledge, this modern myth of creation, will be as viable 1,000 years from now as it is today. Why? Because it is true. Moreover, given the physical, cognitive, social and economic limits constraining further research, science is unlikely to make any significant additions to the knowledge it has already generated. By science I mean not applied science but science at its purest and grandest, the primordial human quest to understand the universe and our place in it. Further research may yield no more great revelations but only incremental, diminishing returns.

ÖйúAƬ

The vast majority of scientists are content to fill in details of the great paradigms laid down by their predecessors. They try to show how a new high-temperature superconductor can be understood in quantum terms, or how a mutation in a particular stretch of DNA triggers breast cancer. But some scientists are much too ambitious for merely "mopping up" after the pioneers. These overreachers want to transcend the received wisdom, to create revolutions in knowledge analogous to those triggered by Darwin's theory of evolution or by quantum mechanics.

For the most part these ambitious types have only one option: to pursue science in a speculative, non-empirical mode that I call ironic science. Ironic science resembles literary criticism or philosophy or theology in that it offers points of view, opinions, which are, at best, "interesting", which provoke further comment. But ironic science does not converge on the truth; unlike atoms and natural selection and the expansion of the universe, which are now established facts, the postulates of ironic science can never be validated through observation and experiment.

The most obvious source of ironic science in this century is social science, which has given us such wonderfully provocative paradigms as Freudian psychoanalysis, Marxism and structuralism. The eminent anthropologist Clifford Geertz of the Institute for Advanced Study in Princeton has suggested that social science is and always will be more akin to literature than to hard sciences such as chemistry or physics. I agree.

But ironic hypotheses have cropped up in the so-called hard sciences as well. One striking specimen is superstring theory, which for more than a decade has been the leading contender for a unified theory of physics. Often called a "theory of everything," it posits that all the matter and energy in the universe and even space and time stem from infinitesimal, string-like particles wriggling in a hyperspace consisting of ten (or more) dimensions.

Unfortunately, the microrealm that superstrings allegedly inhabit is completely inaccessible to human experimenters. A superstring is supposedly as small in comparison to a proton as a proton is in comparison to the solar system. Probing this realm directly would require an accelerator 1,000 light years around. (The entire solar system is only one light day around.) This problem led the Nobel laureate Sheldon Glashow of Harvard University to compare superstring theorists to medieval theologians.

Other ironic theories have also flourished. Cosmologists such as Andrei Linde of Stanford University, for example, have speculated that our cosmos is merely one of an infinite number of universes, some perhaps with laws of physics totally different from our own. Biology has yielded James Lovelock's poetic Gaia hypothesis, which depicts the biosphere as a self-perpetuating organism, and a proposal by Brian Goodwin of the Open University that evolution stems primarily not from natural selection but from mysterious "laws of complexity". Some optimists contend that all these unconfirmable theories are signs of science's vitality and boundless possibilities. I see them as signs of science's desperation and terminal illness.

Most people I have spoken to - scientists and non-scientists alike - reflexively reject the proposition that science is ending. It is easy to understand why. We are drenched in progress. Every year we have smaller, faster computers, sleeker cars, more channels on our televisions. Our views of the future are also distorted by what I call the Star Trek factor. How can science be approaching a culmination when we have not invented spaceships that travel at warp speed yet? Or when we have not acquired the fantastic psychic powers - enhanced by both genetic engineering and electronic prosthetics - described in cyberpunk fiction?

Science itself helps to propagate these fictions. One can find discussions of time travel, teleportation, and parallel universes in reputable, peer-reviewed physics journals. And at least one Nobel laureate in physics, Brian Josephson of the University of Cambridge, has declared that physics will never be complete until it can account for extrasensory perception and telekinesis.

ÖйúAƬ

ÖйúAƬ

To be sure, applied science will continue for a long time to come. Scientists can keep developing versatile new materials; faster and more sophisticated computers; genetic-engineering techniques that make us healthier, stronger, longer-lived; perhaps even fusion reactors that can provide cheap energy with few environmental side effects.

The question is, will these advances in applied science bring about any "surprises," any revolutionary shifts in our basic knowledge? Will they force scientists to revise the map they have drawn of the universe or the narrative they have constructed of the universe's creation and history? Probably not. Applied science in this century has tended to reinforce rather than to challenge the prevailing theoretical paradigms. Lasers and transistors confirm the power of quantum mechanics, just as genetic engineering bolsters belief in the DNA-based model of evolution.

By far the most common objection to my end-of-science spiel, whether I am talking to a Nobel laureate or to my dentist, is some variant of "That's what they thought 100 years ago". Implicit within this response is the following argument: as the 19th century wound down, physicists thought they knew everything. But then Einstein and other physicists discovered relativity and quantum mechanics, opening up vast new vistas for modern physics and other branches of science. Moral: anyone who predicts science is ending will surely turn out to be as short-sighted as those 19th-century physicists were. An anecdote with a similar message alleges that in the 19th century a US patent commissioner quit his job because he thought everything had been invented.

First of all, both of these stories are apocryphal. No American patent official ever quit his job because he thought everything had been invented. And physicists at the end of the last century were engaged in debating such profound issues as whether atoms really exist.

Furthermore, the inductive logic underlying the that's-what-they-thought-at-the-end-of-the-last-century argument is also deeply flawed. Because science has advanced so rapidly over the past century or so, this logic suggests, it can and will continue to do so, possibly forever. But viewed from an historical perspective, the modern era of rapid scientific and technological progress appears to be not a permanent feature of reality but an aberration, a fluke, a product of a singular convergence of economic, political and intellectual factors.

Society has become increasingly sensitive to the adverse consequences of science and technology - such as pollution, nuclear contamination and weapons of mass destruction. This disillusionment with science was foreseen by Oswald Spengler, a German schoolteacher who became the first great prophet of the end of science. In his tome The Decline of the West, published in 1918, Spengler argued that science proceeds in a cyclic fashion, with "romantic" periods of investigation of nature and the invention of new theories giving way to periods of consolidation in which scientific knowledge ossifies.

As scientists become more arrogant and less tolerant of other belief systems, notably religious ones, Spengler declared, society will rebel against science and embrace religious fundamentalism and other irrational systems of belief. Spengler predicted that the decline of science and the resurgence of irrationality would begin at the end of this millennium. Spengler's analysis was, if anything, too optimistic. His cyclic model implies that science may one day be resurrected and undergo a new period of discovery. But science is not cyclic but linear; we can only discover the periodic table and the expansion of the universe and the structure of DNA once.

Modern science, as far as it has come, has left many deep questions unanswered. But the questions tend to be ones that will probably never be definitively answered, given the limits of human science. How, exactly, was the universe created? Could our universe be just one of an infinite number of universes? Could quarks and electrons be composed of still smaller particles, ad infinitum? Was the origin of life, and of creatures intelligent enough to create science, inevitable or just a fluke? What is human nature?

These are the kinds of unanswerable questions that give rise to superstring theory, Gaia, Freudian psychoanalysis and other ironic theories. I do not mean to imply that ironic science has no value. Far from it. Ludwig Wittgenstein once wrote: "Not how the world is, is the mystical, but that it is." The highest state of consciousness, Wittgenstein realised, is pure wonder. At its best, ironic science, like great literature or art or philosophy, induces doubt and awe in us rather than certainty; it keeps us dumbfounded before the mystery of the universe; it ensures that we will never think we have discovered a real "theory of everything," a truth so potent that it extinguishes our sense of wonder forever.

John Horgan is a senior writer on Scientific American. This essay is adapted from his book The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age, just published in the United States by Addison-Wesley. It will be reviewed in The THES by P. W. Anderson in the autumn.

ÖйúAƬ