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Splitting the Moon

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A physicist considers the appeal of miracles.

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Illustration by Stephen Olson. © Stephen Olson.

“Then Moses stretched out his hand over the sea; and the Lord caused the sea to go back by a strong east wind all that night, and made the sea into dry land, and the waters were divided. So the children of Israel went into the midst of the sea on the dry ground, and the waters were a wall to them on their right hand and on their left.”

These words from Exodus describe one of the most famous miracles in the Bible. Never before and never since, in any sea or ocean on earth, have winds created a passageway through which people could walk. In scientific terms, such an event would require a sustained and highly directed column of wind blowing at hurricane force, a phenomenon that could be created only on a small scale in a human-made wind tunnel of the twentieth century. But the parting of the Red Sea occurred three thousand years ago. It was ordered up by Moses and delivered by God. It was a “miracle,” at odds with the behavior of nature, beyond nature, a “supernatural” event, inexplicable except by recourse to divine intervention.

A recent Harris poll found that 74 percent of Americans surveyed believe in God, and 72 percent believe in miracles. Miracles are usually associated with the actions of gods or other divine beings, and they occur not only in Judaism and Christianity but in all of the major religions of the world. In Islam, Muhammad split the moon. In Hinduism, when Saint Jnanadeva was told that he was not qualified to recite the Vedas, he placed his hand on a water buffalo, which proceeded to chant Vedic verses. Most Buddhists believe that all living creatures experience a cycle of deaths and rebirths, appearing in new bodies and passing through various nonphysical realms on the way.

Miracles, by definition, lie outside science. Miracles are incompatible with a rational picture of the physical world. Nevertheless, even in our highly scientific and technological society, with most of us profiting enormously from cell phones and automobiles and other products of science—indeed depending on the consistent workings of science—a large fraction of the public believes in miracles. Most of us do not ponder that contradiction. One of my aunts was certain that her dead father visited her house and spoke to her every few months, and she got a tape recorder—a device of science—to document his voice. (Thereupon, the ghostly visits ceased.)

Miracles come from the world of imagination, of dreams, of desire; science from the world of practicality, of logic, of orderly control. I’ve always been fascinated by our ability to live simultaneously in these two apparently opposing worlds. Each in its own way, they reflect something deep and essential inside of us.

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While miracles that seemingly defy nature have long featured in human history, so too has our quest to codify nature, to enshrine its properties into so-called “laws of nature.” One of the earliest quantitative laws of nature was Archimedes’s principle about the buoyant force of water, presented in his book On Floating Bodies in 250 BC: “If a solid lighter than a fluid be forcibly immersed in it, the solid will be driven upwards by a force equal to the difference between its weight and the weight of the fluid displaced.”

The laws of nature are usually stated in mathematical form. The premier example in the history of science is Isaac Newton’s law of gravity: the strength of the gravitational force between two masses doubles when either mass doubles and increases fourfold when the distance between them is halved. (In mathematical form, F = Gm1 m2 /d2.) It is a rule that Newton derived to explain the orbits of the planets, and it can be used to predict how masses will affect each other through their mutual gravity anywhere in the universe. As an application of Newton’s law: since the moon is one-quarter the size of Earth and approximately one one-hundredth the mass, you would weigh about one-sixth as much on the moon as you do on Earth. (This little-known fact does not appear in the diet books I’ve seen.)

As another example, which you can test for yourself: drop a weight to the floor from a height of four feet and time the duration of its fall. You should get about 0.5 seconds. From a height of eight feet, you should get about 0.7 seconds. From a height of sixteen feet, about one second. Repeat from several more heights and you will discover that the time exactly doubles with every quadrupling of the height, a rule found by Galileo in the seventeenth century. (Mathematically, t = constant x √h.) With this rule, you can now predict the time to fall from any height. You have witnessed, first hand, the regularity of nature.

For centuries, people thought that various forms of knowledge, including knowledge about the workings of nature, were the sole province of God.

Why should nature be lawful? One can imagine a universe in which events happened at random, without any justification or regularity. A wheelbarrow might suddenly float in the air. Day might turn into night and back to day at arbitrary moments. In such a universe, of course, scientists would be out of business. Not only do scientists depend on the logic of nature, most would argue that an irrational and unmathematical universe could not exist. Undoubtedly, the lawfulness of nature, and especially our ability to find those laws—from Archimedes to Newton to Einstein—has brought us a sense of power, a sense of comfort and security, and a sense of control.

Beyond the personal wishes of scientists, the concept of a lawful nature has proven enormously useful. The regular and predictable cycles of the seasons allowed for the development of agriculture. The consistent properties of materials allowed for the development of industry. The repeatable production of T-lymphocytes and other antibodies when exposed to the vaccinia virus allowed the eradication of smallpox, one of the greatest killers of human beings throughout history.

In addition to these practical applications, science has also been able to explain and predict the more esoteric behavior of nature to high accuracy. For example, the orbit of Mercury rotates a slight amount more than could be accounted for by Newton’s seventeenth-century law of gravity. The tiny discrepancy, 0.012 degrees per century, was successfully calculated by Einstein’s modern theory of gravity, general relativity.

Finally, scientists—and to a great extent the population at large—now believe that these laws are discoverable by human beings. That was not always so. In Milton’s Paradise Lost, when Adam enquires about the nature of celestial motions, the angel Raphael replies that “the Great Architect did wisely to conceal, and not divulge His secrets, to be scanned by them who ought rather to admire.” For centuries, people thought that various forms of knowledge, including knowledge about the workings of nature, were the sole province of God, off limits to human understanding. The great success of modern science has challenged that view, whether or not one believes in God. In a sense, the success of science, our own human enterprise, has empowered us to proclaim that nature is lawful.

The above has led to what one might call the Central Doctrine of Science: all properties and events in the physical universe are governed by laws, and those laws hold true at every time and every place in the physical universe. Scientists do not explicitly discuss this doctrine. It is simply assumed. When I was a graduate student in physics, my thesis advisor never mentioned the Central Doctrine of Science, but it was implicit in everything he did in his own professional work and in the guidance he gave to his students. One of my first research problems as a physicist concerned the behavior of very hot gas at the centers of galaxies. For a sufficiently hot gas, electrons and their antiparticles can be created out of the immense thermal energy. Early on, I had to write down the equations governing how matter can be created from energy, a result expressed by Einstein’s famous E=mc2 and confirmed in numerous laboratories on Earth. At no point in my calculations did I have any doubt that the same equations applied to distant galaxies, millions of light years away.

Philosophers debate about whether the “laws of nature” are mere descriptions of nature or necessities of nature, the latter being rules that nature must obey without exception. The Central Doctrine of Science, and the view of most scientists, is that the laws are necessities.

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Throughout time, human beings have had a complex and evolving conception of nature. Mother Nature exists in every culture on earth. She was known as Gaia in ancient Greece, Terra Mater in ancient Rome. Ninsun in ancient Mesopotamia. In India, Gayatri. In Thailand, Phra Mae Thorani. The Māori call her Papatuanuku. Earlier, when Nature was personified, She could be angry and vengeful, loving, indifferent. Many religious traditions today continue to associate deities with nature. The 330 million gods in Hinduism permeate nature. The gods, of course, are not bound by the rules found by science, or any other rules. In such a worldview, the boundaries are blurred between the rational and the irrational, the predictable and the unpredictable, the ordinary and the miraculous.

But even in Judaic-Christian beliefs and traditions, those boundaries are blurred. How else to explain that more than two-thirds of the American public believes in miracles and, at the same time, trusts in science every time they turn the wheel of their car to make a slight correction in direction while traveling at sixty miles per hour on the highway? Having lived myself both in the territory of science (as a physicist) and in the territory of the arts (as a novelist), I would like to offer an opinion about how and why such seeming contradictions occur.

Rarely do we observe the natural world without some mediation by artificial device.

The miraculous has meaning only by contrast to the non-miraculous, the mundane, the normal behavior of nature. In our modern world—climate-controlled buildings, asphalt highways, artificial turf, computers and iPhones with which we can talk to images of our friends thousands of miles away—it appears that most of us have only a vague idea of what is “natural” and what is “unnatural.” Rarely do we observe the natural world without some mediation by artificial device. Even in science, astronomers no longer look directly through the eyepiece of a telescope, but instead see images collected by digital devices called CCDs and presented on computer screens.

In recent years, the environmental movement has somewhat increased our awareness of nature. In his book Earth in the Balance, Al Gore writes, “The disharmony in our relationship to the earth, which stems in part from our addiction to a pattern of consuming ever-larger quantities of the resources of the earth, is now manifest in successive crises, each marking a more destructive clash between our civilization and the natural world.” But even environmental consciousness has not much changed the disconnection between human beings and nature. Most of us still live in cities where we cannot see the star-spangled dark of the night sky. Most of us heat our houses in winter and cool them in summer, insulating ourselves from the cycles of the seasons.

But there is to me a far more compelling explanation for our ability to hold both the miraculous and the non-miraculous in our heads at the same time. Many of us, consciously or unconsciously, believe in some kind of a spiritual universe existing alongside the physical universe. Miracles, then, involve an interaction of those two distinct forms of existence.

Let me mention two exceptions to this division. In Pantheism, a philosophy popularized by Baruch Spinoza in the seventeenth century, there’s no separation between the physical and spiritual universes. There is only a single universe. Nature brims with God. Nature has no boundaries. Nature is everything. In such a situation, the so-called scientific laws of nature describe only one aspect of nature. In the other aspect, the divine, events occur that are indescribable and unpredictable by science. Another exception is Deism, in which the two universes are distinct, but God does not act in the physical universe. There is no intersection. God set the universe in motion and then sat down. Thus, in Deism, miracles cannot occur. Deism, which gained prominence in the Age of Enlightenment, provided a way for people to reconcile their religious beliefs with the rise of modern science.

The more challenging worldview is that in which the spiritual and physical universes are distinct but engage with each other from time to time, in the form of miracles, which break the boundaries of an otherwise law-based existence. In this view, beings and events in the spiritual universe sometimes cross over and appear in the physical universe. Prime examples include the parting of the Red Sea, the Resurrection of Christ, and the splitting of the moon by Muhammad. At a more mundane level, many of us report experiencing “little” miracles in our day-to-day lives, such as memories of existence in a previous life, or premonitions of future events that then happen.

Even some scientists believe in such crossovers. Owen Gingerich, professor emeritus of astronomy and history of science at Harvard University, said to me: “I believe that our physical universe is somehow wrapped within a broader and deeper spiritual universe, in which miracles can occur. We would not be able to plan ahead or make decisions without a world that is largely law-like. The scientific picture of the world is an important one. But it does not apply to all events.” I would estimate that something like 3 to 5 percent of all scientists share Gingerich’s view. Such scientists—who are clearly in the minority—believe that science and the lawfulness of nature hold true most of the time, but that occasionally God intervenes in the physical world and acts in a way that cannot be analyzed by science.

Belief in a spiritual universe, I would suggest, arises to a large extent from a human desire for meaning, meaning both in our individual lives and in the cosmos as a whole. While science provides the psychological comfort of order, rationality, and control, it does not provide meaning. Such deep philosophical questions as “Why am I here?” “What is the purpose of my life?” “What is the meaning of this strange cosmos I find myself in?”, and such moral questions as “Is it right to kill an enemy soldier in time of war?” “Is it right to steal in order to feed my family?”, cannot be answered by science. Yet these questions are vital to our mental and emotional lives. We turn for answers to the spiritual universe, the realm that contains eternal truths and guidance, the realm that has some kind of permanent existence, in contrast to the fleeting moment of our mortal lives. In such a realm, logic, rationality, and regularity are not even part of the vocabulary.

A spiritual universe does not necessarily include God. However, it is usually associated with religion. In his landmark book The Varieties of Religious Experience: A Study in Human Nature (1902), the Harvard philosopher and psychologist William James characterized religion, in its broadest terms, as “the belief that there is an unseen order, and that our supreme good lies in harmoniously adjusting ourselves thereto.” The “order” in James’s conception of religion helps provide meaning. The order must be unseen, since much of what we see in the world and especially in human affairs is chaotic and hard to understand with rational thought. The hypothesized order provides comfort and security. The hypothesized order suggests that there is some purpose in the cosmos. The order comes from outside the physical universe. It comes from the spiritual universe. Paradoxically, for believers, that same unseen order sometimes chooses to violate the orderly laws of nature and produce a miracle.

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I myself do not believe in miracles. I have sometimes wondered why this disbelief has always been strong, even from a young age. I suppose my views have been shaped in part by demonstrations to my own satisfaction that the physical world is a lawful place. (Not so with the world of human affairs, which has always baffled me with its irrationality.) I remember that as a boy of twelve or thirteen, among my many scientific projects, I began making pendulums by tying a fishing weight to the end of a string. I built pendulums of different lengths and timed their swings with a stopwatch. I had read in Popular Science or some other book that the period of the pendulum—the time it takes to make one complete swing—was proportional to the square root of the length of the string. I personally verified that formula and then used it to predict the periods of new pendulums even before I had made them. How amazing, I thought, that this simple formula worked over and over again—at my house, at my friends’ houses, anywhere. By contrast to the erratic ups and downs and unpredictable behavior of my brothers and mother and father, nature was reliable.

The history of science has been a history of constant progress in discovering the laws of nature.

As I got older, I learned more and more about the laws of nature, about what scientists did, and I didn’t see any evidence of a supernatural world. It seemed to me, and still seems to me, that everything we experience in the physical world can be explained in terms of repeatable and universal laws of nature. We certainly don’t have a complete set of the laws of nature, but I join most scientists in believing that a complete set of laws exists. The history of science has been a history of constant progress in discovering the laws of nature.

At the same time, it seems extremely unlikely to me that there is another kind of reality, an Intelligence or Being that exists outside the physical universe but that can enter our time and space at will. I simply have seen no evidence for such a thing.

In this regard, I have always put stock in Occam’s Razor. Among competing hypotheses to explain events, go with the simplest, the one that requires the least number of assumptions, until that hypothesis is proven wrong. If events in the physical universe can be explained by laws of nature, then why invoke anything beyond nature? To my mind, the parting of the Red Sea and other reported miracles are not documented and confirmed. Furthermore, they contradict the reality that I have come to embrace through countless personal experiences with nature, big and small, from my childhood experiments to my research in physics to my everyday life in the world.

My wife and I spend summers on a small island in Maine, far from any town. At night, the skies are quite dark. Sometimes, when there is no wind blowing and the tidal flow is small and the ocean is very still, I can see the reflection of the stars in the water near our dock. At such moments, the water looks like a dark carpet with a million tiny sparkles of light, which gently bob and ripple with each passing wave. Even though I know all the science, I am totally mesmerized and awed. For me, that is miracle enough.

G

Alan Lightman is an American writer, physicist, and social entrepreneur. Lightman has served on the faculties of Harvard and the Massachusetts Institute of Technology (MIT) and is currently professor of the practice of the humanities at MIT. His essays and articles have appeared in The Atlantic, Granta, Harper’s, The New Yorker, The New York Review of Books, Salon, and many other publications. His novels include Einstein’s Dreams, an international bestseller, and The Diagnosis: A Novel, a finalist for the National Book Award. Essays from his recent book The Accidental Universe: The World You Thought You Knew were chosen as best essays of the year by the New York Times and featured on NPR. In 2005, Lightman founded the Harpswell Foundation, whose mission is to empower a new generation of women leaders in Cambodia.

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