The Devil's Delusion

“THOUSANDS HAVE lived without love,” W. H. Auden observed, “not one without water.” Love is important; water is necessary. If water is necessary, so, too, a great many other things. In a paper entitled “Large Number Coincidences and the Anthropic Principle in Cosmology,” published in 1974, the physicist Brandon Carter observed that many physical properties of the universe appeared fine-tuned to permit the appearance of living systems.

What a lucky break—things have just worked out.

What an odd turn of phrase—fine-tuned.

What an unexpected word—permit.

Whether lucky, odd, or unexpected, the facts are clear. The cosmological constant is a number controlling the expansion of the universe. If it were negative, the universe would appear doomed to contract in upon itself, and if positive, equally doomed to expand out from itself. Like the rest of us, the universe is apparently doomed no matter what it does. And here is the odd point: If the cosmological constant were larger than it is, the universe would have expanded too quickly, and if smaller, it would have collapsed too early, to permit the appearance of living systems. Very similar observations have been made with respect to the fine-structure constant, the ratio of neutrons to protons, the ratio of the electromagnetic force to the gravitational force, even the speed of light.

Why stop? The second law of thermodynamics affirms that, in a general way, things are running down. The entropy of the universe is everywhere increasing. But if things are running down, what are they running down from? This is the question that physicist and mathematician Roger Penrose asked. And considering the rundown, he could only conclude that the runup was an initial state of the universe whose entropy was very, very low and so very finely tuned.

Who ordered that?

“Scientists,” the physicist Paul Davies has observed, “are slowly waking up to an inconvenient truth—the universe looks suspiciously like a fix. The issue concerns the very laws of nature themselves. For 40 years, physicists and cosmologists have been quietly collecting examples of all too convenient ‘coincidences’ and special features in the underlying laws of the universe that seem to be necessary in order for life, and hence conscious beings, to exist. Change any one of them and the consequences would be lethal.”

These arguments are very much of a piece with those that Fred Hoyle advanced after studying the resonances of carbon during nucleosynthesis. “The universe,” he grumbled afterward, “looks like a put-up job.” An atheist, Hoyle did not care to consider who might have put the job up, and when pressed, he took refuge in the hypothesis that aliens were at fault. In this master stroke he was joined later by Francis Crick. When aliens are dropped from the argument, there remains a very intriguing question: Why do the constants and parameters of theoretical physics obey such tight constraints?

If this is one question, it leads at once to another. The laws of nature are what they are. They are fundamental. But why are they true? Why do material objects attract one another throughout the universe with a kind of brute and aching inevitability? Why is space-and-time curved by the presence of matter? Why is the electron charged?

Why? Yes, why?

An appeal to still further physical laws is, of course, ruled out on the grounds that the fundamental laws of nature are fundamental. An appeal to logic is unavailing. The laws of nature do not seem to be logical truths. The laws of nature must be intrinsically rich enough to specify the panorama of the universe, and the universe is anything but simple. As Newton remarks, “Blind metaphysical necessity, which is certainly the same always and everywhere, could produce no variety of things.”

If the laws of nature are neither necessary nor simple, why, then, are they true?

Questions about the parameters and laws of physics form a single insistent question in thought: Why are things as they are when what they are seems anything but arbitrary?

One answer is obvious. It is the one that theologians have always offered: The universe looks like a put-up job because it is a put-up job. That this answer is obvious is no reason to think it false. Nonetheless, the answer that common sense might suggest is deficient in one respect: It is emotionally unacceptable because a universe that looks like a put-up job puts off a great many physicists.

They have thus made every effort to find an alternative. Did you imagine that science was a disinterested pursuit of the truth?

Well, you were wrong.

APOTHEOSIS IN THE STANDARD MODEL

At the beginning of the 1960s, physicists understood that there were four forces in play in the material world: the force of gravitation, the electromagnetic force, and the weak and strong nuclear forces. They had in addition come into possession of a remarkably large number of elementary particles, so many that Enrico Fermi complained that had he wished to memorize their names, he would have become a botanist.

Thirteen years later, three of the four forces and virtually all of the elementary particles had been successfully classified, and the forces partially explained because partially unified. This is the triumph of the Standard Model.

It is a model comprising three parts. The first is quantum electrodynamics, which offers a successful quantum theory of the electromagnetic field, one satisfying principles of both quantum mechanics and special relativity. Quantum electrodynamics was completed in the late 1940s by Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga; and because it describes electromagnetic phenomena—light, electricity, magnetism—it retains a vivid connection with the world of daily life in which computer chips and electric toasters hum in accordance with its laws. Without it, we would all be lost, or at best, inconvenienced.

The second part of the Standard Model, Steven Weinberg, Sheldon Glashow, and Abdus Salaam created in their electroweak theory. As the name might indicate, their theory unified the weak nuclear force and the electromagnetic force. By showing that, deep down, two forces were really one, Weinberg, Glashow, and Salaam demonstrated that when properly seen, the weak nuclear force and the electromagnetic force were manifestations of some ancient primordial form of unity. In the world as it is, of course, very little of this unity is left. The weak nuclear force and the electromagnetic force are today distinct. To see things as they really are, it is necessary to see things as they really were. The time when things really were unified occurred shortly after the Big Bang. To account for the fact that in the world as it is observed, the weak force and the electromagnetic force are distinct, Weinberg, Glashow, and Salaam appealed to the audacious idea that what physicists could today see of the weak and electromagnetic forces represented nothing more than a form of broken symmetry, as when couples remember how happy they once were amid the shambles of their discontent.

There is finally quantum chromodynamics, which provides a theory of the strong nuclear force. In 1954, C. N. Yang and Robert Mills outlined a daring generalization of quantum electrodynamics. Their paper described a new physical theory. It also predicted the existence of particles that no experiment had revealed and strange new symmetries.

With the proliferation of quarks and their varieties in the 1960s, new particles and symmetries did emerge, and they proved to be precisely those that would allow a Yang-Mills theory to take charge of the strong nuclear force and give it direction and a general shaping-up.

There followed a decisive step, the last. Experiments had indicated that in some bizarre fashion, particles bound by the strong nuclear force behaved in ways quite unlike particles governed by the weak nuclear force—or any other force, for that matter. Their interactions seemed to grow stronger as the distance between them increased, almost as if they were being held together by a rubber band that remained flaccid at short distances and tense at longer distances. Many marriages are like this. In the early 1970s, David Gross, H. David Politzer, and Frank Wilczek discovered in their theory of asymptotic freedom that this was an expected consequence of a Yang-Mills theory of the strong nuclear force.

The Standard Model was complete.

If the Standard Model is a triumph, is not one that is unalloyed. The Standard Model cannot explain the transition from the elementary particles to states of matter in which the elementary particles are bound to one another and so form complex structures. It is in this sense incomplete.

The Standard Model is not only incomplete but arbitrary. Like any physical theory, it contains a good many numerical parameters—at least twenty-one. These designate specific numerical properties of the model. These cannot be derived from the theory. Physicists thus find themselves very much in the position of a master couturier obliged to allow one of his finest creations to appear on the runway with its basting lines and tacking pins still affixed.

Above all, the Standard Model is inadequate because it does not incorporate the force of gravity. General relativity stands apart. The two great theories of the twentieth century have not been reconciled. They invoke different languages, different ideas, and different techniques of calculations. The great technical triumphs that made the Standard Model a success are with respect to general relativity unavailing because ineffective. General relativity and quantum mechanics resemble two aging matadors facing the bull of nature, the both of them retiring flustered after a number of halfhearted veronicas and ineffective passes.

The bull is still there, snorting through velvet nostrils. He does not seem the least bit fatigued.

OVERFLOW INTO STRINGS

For the past quarter-century, a very substantial portion of the community of mathematical physicists has been engaged in work on a subject known as string theory. The effort has consumed the best minds of a generation.

Whereupon the inevitable, Wait a minute, strings?

Yes, strings. A string is just what its name suggests. It is a wiggling one-dimensional object, something like a garden hose although somewhat smaller, and extended in length but not width. Strings can be straight, they can be curved, they can join with themselves to form loops, and what is more, since they are strings, they can vibrate under tension.

The idea has had a tremendous unifying power, suggesting that nature’s elementary particles could be recovered from one fundamental object vibrating in various ways. In place of the very complicated system of precisely adjusted forces and parameters characteristic of the Standard Model, string theory pointed to two, and only two, fundamental constraints: The first reflected the string’s tension, and so served as the key to its powers of creation; and the second, its coupling constant, the measure of how likely it was to break into two.

Nothing more was needed. This was widely considered a very fine thing.

There followed an illumination, one that lit up all of particle physics. Working very much in isolation, the physicists Joël Scherk and John Schwarz observed that string theory, no matter how manipulated, seemed to predict the existence of a new particle, something like the photon. This seemed to be something uncalled for and therefore unwanted, until physicists realized that amid all those twitching strings, a particle had appeared conveying the force of gravity. For the first time, a fundamental theory in particle physics seemed to incorporate a long-missing force. A grand unification seemed to be at hand, one involving all nature’s forces. No theory could be more final—or more desired—than this.

From that moment on, a number of physicists had the rarest of all experiences: They came to believe that they could hear Nature herself knocking at their door.

In the years that followed—roughly from the late 1970s until the present—string theory expanded and grew great. Difficulties appeared and were surmounted, whereupon new difficulties appeared. Physicists were obligated to undertake very difficult calculations with respect to a theory that they did not completely understand. Their work revealed strange coincidences and tantalizing suggestions of a deeper form of unity. By the early part of the twenty-first century, they could look back on two string theoretic revolutions, and while both advanced the cause, neither brought the goal of a single, clearly stated final theory within reach.

The reaction, although slow in coming, was also inevitable. String theory was criticized in the popular press by a distinguished theoretical physicist and a mathematician. In The Trouble with Physics, written by Lee Smolin, and Not Even Wrong, by Peter Woit, string theory was examined with some sympathy and found wanting. Neither author could find a theory in the place where theoreticians said a theory should be, and both authors noted with some asperity that string theory had no apparent connections to experiment and that none were in prospect. Woit went so far as to observe that the mathematical structure on which the theory rested, far from being a thing of great elegance, was the most horrible thing he had ever seen.

Whatever their other merits, all string theories are characterized by an embarrassing dimensional overflow. Some versions of string theory require twenty-six dimensions; others, ten; and still others, eleven. Our own universe contains only three or four, but in any case, no more than a handful. It is one thing to consider higher dimensions as mathematical artifacts. Mathematicians have no difficulty in dealing with an infinite dimensional space. They do it all the time. But the extra dimensions of string theory are not purely mathematical. They are within string theory quite real, if only because they have useful work they must do. If real, those extra dimensions are nonetheless invisible. As one might easily imagine, the conflict between the demands of theory—Get me those extra dimensions—and the constraints of common sense—No extra dimensions here, Boss, and we looked—was not easily resolved.

In the end, string theorists argued that the extra dimensions of their theory were buried somewhere. At each point in space and time, they conjectured, there one would find a tiny geometrical object known as a Calabi-Yau manifold, and curled up within, there one would find the extra dimensions of string theory itself.

It was an idea that possessed every advantage except clarity, elegance, and a demonstrated connection to reality.

With extra dimensions buried, stable solutions emerged from the equations of string theory, just as the physicists had hoped. They were not, unfortunately, unique. There were thousands of them, and each led to a different version of the theory, a point in an enormous space of possibilities, a landscape of a sort never seen before, a place where each point seemed to embody a different scheme of physical thought, and so a different universe governed by the scheme. In its appearance in various popular journals, the mutant thing was depicted as a gigantic set of bubbles floating in space, our own universe a dimpled dot lost somewhere amid that infernally expanding froth.

FLIGHT INTO THE FANTASTIC

String theory confronted the community of particle physicists with an exquisite dilemma. A theory that initially seemed too good to be true had by the late 1990s seemed too good to be true. This was widely considered monstrously unjust.

If string theory did not uniquely describe one universe, physicists reasoned, the fault lay with our universe: It was not man enough to handle so promiscuous a theory. One universe having proved inadequate, more would be required. Endeavoring to unify the forces of nature, physicists determined to multiply the universes in which they were satisfied. Very few physicists appreciated the irony involved in pursuing the first ambition by embracing the second. The physicist Leonard Susskind thus claimed that “the narrow 20th-century view of a unique universe, about ten billion years old and ten billion light years across with a unique set of physical laws, is giving way to something far bigger and pregnant with new possibilities.”

Far bigger? And pregnant too? In service to this idea, Susskind wrote that “physicists and cosmologists are coming to see our ten billion light years as an infinitesimal pocket of a stupendous megaverse.” On reflection, Susskind came to understand that the word megaverse carried negative class associations, as in mega-blockbuster (a movie no one wishes to see) or mega-mall (a place no one wishes to go), whereupon he renamed the megaverse “the Landscape.”

The Landscape at once suggested the radical changes to come. “Theoretical physicists,” Susskind wrote, “are proposing theories which demote our ordinary laws of nature to a tiny comer of a gigantic landscape of mathematical possibilities.”

Each of the versions of string theory is thus free to find its home in some particular universe. Like Odysseus worshipping in foreign temples, there is a universe in which a very large cosmological constant is made to feel welcome. The MIT physicist Max Tegmark is persuaded that this is so, and if in some universe he is persuaded that it is not so, he has learned to accept the emotional incoherence that would trouble others with equanimity.

However named, the Landscape was a provocative, and even a revolutionary idea. Physicists appreciate revolutions for obvious reasons: They stir the blood. “We may be at a new turning point, a radical change in what we accept as a legitimate foundation for a physical theory,” Steven Weinberg wrote. It would be hard to imagine a doctrine more radical than the thesis that when it comes to universes, there are a great many of them. At a conference on string theory held in 2005, Weinberg buoyantly indicated that he was prepared to welcome his new insect overlords.

An informal poll indicated that the audience of physicists rejected his views by a margin of four to one.

“We win some and we lose some,” Weinberg remarked equably.

The Landscape is a new idea in physical thought, but it is not a new idea. Philosophers have long found the restriction of their thoughts to just one universe burdensome. In the late 1960s, David Lewis assigned possible worlds ontological benefits previously reserved to worlds that are real. In some possible world, Lewis argued, Julius Caesar is very much alive. He is endeavoring to cross the Hudson instead of the Rubicon, and fuming, no doubt, at the delays before the toll booth on the George Washington Bridge. It is just as parochial to reject this world as unreal, Lewis argued, as it would be to reject Chicago because it cannot be seen from New York. Lewis argued brilliantly for this idea, known as modal realism. The absurdity of the resulting view was not an impediment to his satisfaction. Or to mine, needless to say.

Quantum mechanics has also invited the promotion of possible worlds to the ontological Big Time, as readers may remember from chapter 5, where dead-cat universes proliferated alongside universes containing live cats.

During the 1980s, the physicist Alan Guth argued that the early universe was characterized by a period of exponential inflation. Very soon after it blew up in the first place, it blew up again. When suitably blown up, it stopped blowing up. The Stanford physicist André Linde carried this idea a step further in his theory of eternal chaotic inflation. Universes are blowing up all over the place. They cannot stop themselves.

When string theorists talk about the Landscape, they are among friends. If their friends were willing to believe in anything, string theorists, having so lately consorted with twenty-six dimensions, are hardly in a position to complain.

There is no need to turn to such esoteric doctrines to capture the underlying current of thought that animates the Landscape. It is simply the claim that given sufficiently many universes, what is true here need not be true there, and vice versa. This thesis has been current in every college classroom for at least fifty years. It arises spontaneously in discussion, like soap bubbles in water. It is expressed in the same way and often by the same stolid, heavy-thighed undergraduate—a Mr. Waldburg, in my case and class.

After raising his hand with the air of a man compelled to observe the obvious, he has this to say: There are no absolute truths.

Waldburg, meet Weinberg.

THE SURE THING

Although initiated as a whim, the Landscape has been welcomed by string theorists as a deliverance. Whether string theory is rescued by the Landscape is relatively a trivial matter. Theories come and go, and if this one goes, another is sure to come. The Landscape has acquired a life of its own because it is addressed to issues that arise whatever the theory whenever it arrives. If science, as the French mathematician René Thom once remarked, is an attempt to reduce the arbitrariness of our descriptions, then every theory short of one that is logically necessary must in the end provoke the same two questions: Why are its numerical parameters as they are? And why are its assumptions what they are?

The Landscape provides a generic answer. It is all-purpose in its intent. It works no matter the theory. And it works by means of the simple principle that by multiplying universes, the Landscape dissolves improbabilities. To the question What are the odds? the Landscape provides the invigorating answer that it hardly matters. If the fine-structure constant has in our universe one value, in some other universe it has another value. Given sufficiently many universes, things improbable in one must from the perspective of them all appear certain.

The same reasoning applies to questions about the laws of nature. Why is Newton’s universal law of gravitation true? No need to ask. In another universe, it is not.

The Big Fix has by this maneuver been supplanted by the Sure Thing.

As one half of the flight into the fantastic, the Landscape does what it can, and what it does, it does very well. It dilutes the acrid acid of improbability. But as philosophers and physicists at once observed, the Landscape offers a general solution to what is, in fact, a particular problem. The multiplication of universes establishes that in some universe, the fine-structure constant will take any designated value. It is a Sure Thing. Nonetheless, the Sure Thing establishes only that life’s lucky numbers will sooner or later turn up somewhere or other.

And yet they have turned up here, just where we need them the most. Requiring certain amenities, we find ourselves in a universe in which they have been liberally supplied. This may not be a paradox in thought, but surely it seems a very good deal. We might well have found ourselves in a far less agreeable universe, one in which none of life’s lucky numbers were tuned to their sweet spot.

And where would we have been then?

The Landscape now works hand in glove with a second radical idea in physical thought. In the same paper in which he drew attention to the question of fine tuning, Brandon Carter observed that “the universe must be such as to admit the creation of observers within it at some stage.” Such is the Anthropic Principle, or, at least, one of them, since the principle now comes in a variety of forms and flavors. It consists, when analyzed, of two quite separate claims.

The first is a matter of common sense. If the universe had not admitted the creation of observers at some stage, why, then, we would not be here.

The second is a claim about the facts of life. If we are surprised by a universe in which we have been given what we need, some part of that surprise, Carter argued, represents a form of bad faith. If the necessities of life are necessary, they must be inevitable. And if inevitable, whence the surprise?

The simple fact that we are where we are is sufficient to explain why we have what we have.

What more could anyone ask?

The question why the ultimate laws of nature are true, and why its numerical parameters have the value that they do, now admits of a two-part response. The first is provided by the Landscape. Neither the numbers nor the laws represent anything improbable. And the second by the Anthropic Principle: If they were false, or if they had different values, where would you be?

Nowhere, right?

And yet here you are.

What did you expect?

IF EVERYTHING GOES

The great difficulty with the Landscape and the Anthropic Principle is that physicists prepared to welcome these ideas had no way in which to control them, while physicists prepared to reject them had no way in which to avoid them. In a stimulating paper entitled “Multiverses and Physical Cosmology,” the distinguished cosmologists G.F.R. Ellis, U. Kirchner, and W. R. Stoeger considered the idea that in the Landscape anything goes because everything is possible. “In some universes,” they write, “there will be a fundamental unification of physics expressible in a basic ‘theory of everything,’ in others this will not be so.”

But having advanced this conjecture, Ellis, Kirchner, and Stoeger have neglected to tell us whether it is true across the Landscape. If so, then not everything goes; and if not, how could it be of interest?

This is, to be sure, something that Ellis, Kirchner, and Stoeger recognize. At the beginning of their essay, they observe that “the very existence of [the Landscape] is based on an assumed set of laws… which all universes… have in common.” It is only later in their essay that they forget what they have written.

I know just how it is, fellas. I can never remember where I left my keys.

The speed with which a commitment to the Landscape ends in incoherence, while it is alarming, is not unexpected. “Any scientist,” Steven Weinberg writes in defending his endorsement of anthropic reasoning, “must live in a part of the landscape where physical parameters take values suitable for the appearance of life and its evolution into scientists.” To say that portions of the Landscape are “suitable” for the appearance of life is to say that it is there that life is possible. But if life is possible there, it is not possible elsewhere. Human beings could not, presumably, investigate the universe from the interior of the sun. It is too warm and entirely too gassy. If life is not possible elsewhere, then it is necessarily impossible elsewhere. But what might justify this powerful claim if not some physical principle true everywhere? If a principle about life is general throughout the Landscape, this would seem to make purely local matters of biology supreme matters of physical thought. This assigns to living systems a degree of cosmic importance that only theologians suspected they possessed.

Given issues such as these, it is at least possible to wonder whether the Landscape and the Anthropic Principle are contrivances in just the sense that Ptolemaic epicycles were contrivances. The Landscape has, after all, been brought into existence by assumption. It cannot be observed. It embodies an article of faith, and like so much that is a matter of faith, the Landscape is vulnerable to the sadness of doubt. There are by now thousands of professional papers about the Landscape, and reading even a handful makes for the uneasy conviction that were physicists to stop writing about the place, the Landscape, like Atlantis, would stop existing—just like that.

This cannot be said of the sun.

When physicists come to defend the Landscape, they use language more commonly heard among biologists. Lee Smolin has argued that deep down there is little evidence in favor of string theory, and even less in favor of the Landscape. So, what of it? Leonard Susskind responded: “The level of confidence that string theorists have for their theory is based on a web of interconnected pieces of evidence that is so compelling that genuine mathematicians have no doubt about its validity.”

Sentiments of this sort must be appreciated for their speculative inventiveness, if nothing else. Evidence so compelling that no part of it need be produced is not evidence at all. The thesis that a scientific theory represents a “web of interconnected pieces” describes with some economy of effect the Summa Theologica of Thomas Aquinas. Or a house of cards.

Very basic physical questions about the Landscape have yet to be answered. On the one hand, there are a very large number of physical theories. They represent a spectrum of possibilities, an immersion into what laws might be true, and what numerical parameters might be in control of things. On the other hand, there are the universes in which they are satisfied, strange, remote, distant, unrecoverable. Physicists very often write as if in the crucible of creation, universes were forever pullulating, red-eyed and throbbing with energy. Perhaps this is so. Who am I to say? But what is left unexplained on these stirring metaphysical accounts is the relationship between those numberless theories and those numberless universes. Just how does a theory get hold of a universe in order to control its birth, formation, and development?

It must do that, because in the end this is just what a theory does, and if it does not do it, then nothing in the Landscape is explained by anything.

But this once again returns the discussion to the point at which it began. If there are such overall principles in charge of the Landscape, why are they true?

Questions such as this reflect in the end a single point of intellectual incoherence. The thesis that there are no absolute truths—is it an absolute truth? If it is, then some truths are absolute after all, and if some are, why not others? If it is not, just why should we pay it any mind, since its claims on our attention will vary according to circumstance?

As a physical claim, the Anthropic Principle hardly seems to enjoy the same authority as the conservation of energy. It is in one sense trivial. We see what we can. But efforts to move the principle from the place in which platitudes congregate have not been entirely successful. Can we really explain the necessities of life by the fact that we are enjoying them? In 1 Kings of the Hebrew Bible, the prophet Elijah, lost in the desert and without food or water, sat underneath a juniper tree and waited for death. An angel appeared, offering him refreshment. What Elijah took, he of course needed, and since he needed what he took, what he took was sufficient to account for his survival. Biblical commentators have wisely refrained from explaining the angel’s appearance on these grounds. The angel, they observed, was sent to Elijah by God. That is the proper explanation for its appearance. No matter the extent to which we need the laws and parameters of the physical world to be as they are, that by itself cannot explain the fact that they are as they are.

It is odd that men who as a group are united by their conviction that religious beliefs are very primitive should find themselves disputing matters more commonly discussed in the Alpha Phi Alpha keg room. It is so nonetheless, a point that the brothers find hardly surprising. Discussions on various Internet postings are endless. Often they contain an eerie mixture of technical sophistication and philosophical incompetence. Or the other way around. The willingness of physical scientists to explore such strategies in thought might suggest to a perceptive psychoanalyst a desire not so much to discover a new idea as to avoid an old one.

Such things happen. And they happen even in mathematical physics.

Received wisdom has it that lacking access to the mysteries of science, men and women accept instead the mysteries of faith. This diagnosis is very often expressed in terms of evolutionary theory. The human brain is an instrument shaped by selection for survival, and it is only natural, considering the problems they faced many years ago, that anxious men and women should have turned toward elaborate theological speculation. What better hedge against fearsome predators or an uncertain food supply than the Immaculate Conception or the revelations of the Gematria? As general relativity or quantum field theory become more widely known, human gullibility will decline.

This is not a view of things that a close study of string theory, the Landscape, or the Anthropic Principle tends to support.

GOD, LOGIC, NOTHING

Joel Primack, a cosmologist at the University of California, Santa Cruz, once posed an interesting question to the physicist Neil Turok: “What is it that makes the electrons continue to follow the laws.”

Turok was surprised by the question; he recognized its force. Something seems to compel physical objects to obey the laws of nature, and what makes this observation odd is just that neither compulsion nor obedience are physical ideas.

Medieval theologians understood the question, and they appreciated its power. They offered in response the answer that to their way of thinking made intuitive sense: Deus est ubique conservans mumdum. God is everywhere conserving the world.

It is God that makes the electron follow His laws.

Albert Einstein understood the question as well. His deepest intellectual urge, he remarked, was to know whether God had any choice in the creation of the universe. If He did, then the laws of nature are as they are in virtue of His choice. If He did not, then the laws of nature must be necessary, their binding sense of obligation imposed on the cosmos in virtue of their form. The electron thus follows the laws of nature because it cannot do anything else.

It is logic that makes the electron follow its laws.

And Brandon Carter, Leonard Susskind, and Steven Weinberg understand the question as well. Their answer is the Landscape and the Anthropic Principle. There are universes in which the electron continues to follow some law, and those in which it does not. In a Landscape in which anything is possible, nothing is necessary. In a universe in which nothing is necessary, chaos is possible.

It is nothing that makes the electron follow any laws.

Which, then, is it to be: God, logic, or nothing?

This is the question to which all discussions of the Landscape and the Anthropic Principle are tending, and because the same question can be raised with respect to moral thought, it is a question with an immense and disturbing intellectual power.

For scientific atheists, the question answers itself: Better logic than nothing, and better nothing than God. It is a response that serves moral as well as physical thought. Philosophers such as Simon Blackburn, who believe that it is their special responsibility to decline theological appeals, also find themselves forced to choose between logic and nothing.

It is a choice that offers philosophers and physicists little room in which to maneuver. All attempts to see the laws of nature as statements that are true in virtue of their form have been unavailing. The laws of nature, as Isaac Newton foresaw, are not laws of logic, nor are they like the laws of logic. Physicists since Einstein have tried to see in the laws of nature a formal structure that would allow them to say to themselves, “Ah, that is why they are true,” and they have failed. Before determining that he would welcome in the form of the Landscape and the Anthropic Principle ideas that previously he was prepared to reject, Steven Weinberg argued that when at last we are face-to-face with the final theory, we shall discover that it is unique. It is what it is. It cannot be changed. And it is precisely the fact that it cannot be changed that offers the soul surcease from anxiety. In the end, this idea does not serve the cause. If it is impossible to change the structure of a final theory, then uniqueness is simply a coded concept, one standing for necessity itself. And if it is not impossible, the claim that the final laws of nature are unique comes to little more than this: They are what they are, and who on earth knows why?

While better logic than nothing is still on the menu, it is no longer on the table. There remains better nothing than God as the living preference among physicists and moral philosophers. It is a remarkably serviceable philosophy. In moral thought, nothing comes to moral relativism; and philosophers who can see no reason whatsoever that they should accept any very onerous moral constraints have found themselves gratified to discover that there are no such constraints they need accept. The Landscape and the Anthropic Principle represent the accordance of moral relativism in physical thought. They work to cancel the suggestion that the universe—our own, the one we inhabit—is any kind of put-up job. This is their emotional content, the place where they serve prejudice. These ideas have an important role to play in the economy of the sciences, and for this reason, they have been welcomed by the community of scientific atheists with something akin to a cool murmur of relief. They have, for example, worked entirely to Richard Dawkins’s satisfaction. He believes them superior to the obvious theological alternatives on the grounds that it is better to have many worlds than one God.

But before his enthusiasm is dismissed as obviously contrived, it should be remembered that just these principles have led to a startling physical prediction. Using the ideas of the Landscape and the Anthropic Principle, Steven Weinberg predicted that the cosmological constant, as it is observed, should have a small, positive value. In this he was correct. This is very remarkable and it suggests that just possibly these ideas have a depth somewhat at odds with their apparently frivolous character.

I do not know. It does not hurt to say so.

But one possibility in thought should certainly encourage another. If nothing proves unavailing, will physicists accept the inexorable logic of the disjunction God or nothing?

Writing with what I think is characteristic honesty, Leonard Susskind has this to say:

This remark has an unintended daring. It gives a good deal of ground away. It is generous. And it suggests oddly enough that a conflict in thought that scientists have almost universally dismissed retains a strange, disturbing vitality nonetheless. Do not be misled by phrases such as “faith-based as ID.” It is the word awkward that counts. If the double ideas of the Landscape and the Anthropic Principle do not suffice to answer the question why we live in a universe that seems perfectly designed for human life, a great many men and women will conclude that it is perfectly designed for human life, and they will draw the appropriate consequences from this conjecture.

What is awkward is just that at a moment when the community of scientists had hoped that they had put all that behind them so as to enjoy a universe that was safe, sane, secular, and sanitized, somehow the thing they had been so long avoiding has managed to clamber back into contention as a living possibility in thought.

This is very awkward.