Science can't tell us everything: Faith, physics and the origin of the universe

Recognizing the limits of science doesn't mean surrendering to religion, but being free to understand ourselves

Published June 8, 2014 2:00PM (EDT)

Neil deGrasse Tyson                                          (AP/Frank Micelotta)
Neil deGrasse Tyson (AP/Frank Micelotta)

Excerpted from "The Island of Knowledge: The Limits of Science and the Search for Meaning"

The Will to Believe
(Wherein we explore the role of belief and extrapolation in religion and in scientific creativity)

Can we make sense of the world without belief? This is a central question behind the science and faith dichotomy, one that informs how an individual chooses to relate to the world. Contrasting mythic and scientific explanations of reality, we could say that religious myths attempt to explain the unknown with the unknowable while science attempts to explain the unknown with the knowable. Much of the tension stems from assuming that there are two mutually inconsistent realities, one within this world (and thus “knowable” through the diligent application of the scientific method) and one without (and thus “unknowable” or intangible, traditionally related to religious belief).

In myths, the unknowable reflects the sacred nature of the gods, whose existence transcends the boundaries of space and time. In the words of historian of religion Mircea Eliade:

For the Australian as well as for the Chinese, the Hindu and the European peasant, the myths are true because they are sacred, because they tell him about sacred beings and events. Consequently, in reciting or listening to a myth, one resumes contact with the sacred and with reality, and in so doing one transcends the profane condition, the “historical situation.”

Throughout the ages, religious myths have allowed the faithful to transcend the “profane condition,” the perplexing awareness we humans have of being creatures bound by time, of having a history and an end. At a more pragmatic level, mythic explanations of natural phenomena were prescientific attempts to make sense of things that were beyond human control, answering questions that seemed unanswerable. Why should the Sun go across the sky every day? To the Greeks, because Apollo transported it in his fiery chariot. To the Navajos of the American Southwest, it was Johonaa’ei who hauled the Sun daily on his back across the sky. To the Egyptians, this task belonged to Ra, who transported the Sun in his boat. In a strictly naturalistic sense, the motivation behind such myths is not so different from that of science, as both attempt to uncover the hidden mechanisms behind natural phenomena: after all, gods and physical forces make things happen, albeit in very distinct ways.

More to the point, both the scientist and the faithful believe in unexplained causation, that is, in things happening for unknown reasons, even if the nature of the cause is completely different for each. In the sciences, this belief is most obvious when there is an attempt to extrapolate a theory or model beyond its tested limits, as in “gravity works the same way across the entire Universe,” or “the theory of evolution by natural selection applies to all forms of life, including extraterrestrial ones.” These extrapolations are crucial to advance knowledge into unexplored territory. The scientist feels justified in doing so, given the accumulated power of her theories to explain so much of the world. We can even say, with slight impropriety, that her faith is empirically validated.

Here is an example. Newton’s theory of universal gravitation, as explained in Book III of his revolutionary Mathematical Principles of Natural Philosophy, the Principia, should really have been called a theory of solar system gravitation, since by the late seventeenth century no tests were conceivable beyond its confines. Yet Newton called Book III The System of the World, assuming that his description of gravitational attraction as a force proportional to the quantity of mass in two bodies and decreasing with the square of the distance between them would extend to the whole “world,” that is, the cosmos. In his own words, from Book III,

Finally, if it is universally established by experiments and astronomical observations that all bodies on or near the earth gravitate toward the earth, and do so in the proportion of matter in each body, and that the moon gravitates toward the earth in proportion to the quantity of its matter, and that our sea in turn gravitates toward the moon, and that all planets gravitate toward one another, and that there is a similar gravity of comets toward the sun, it will have to be concluded by this third rule that all bodies gravitate toward one another.

Newton cleverly avoided speculating on the cause of gravity itself—“I feign no hypothesis”—attaching it universally to all bodies with mass: “And to us it is enough that gravity does really exist, and acts according to the laws which we have explained, and abundantly serves to account for all the motions of the celestial bodies, and of our sea,” he wrote in the General Scholium of the Principia, a sort of concluding explanatory text. He didn’t know why masses attract one another, but he knew how they did so. The Principia was a book concerned with the hows and not with the whys.

Later, in a letter to the Cambridge theologian Richard Bentley dated December 10, 1692, Newton used his extrapolation on the nature of the gravitational force to justify why the universe should be infinite, a major turning point in the history of cosmological thought. If gravity acted across a spatially finite universe according to the same law of attraction, Bentley wondered, why wouldn’t all matter be concentrated in a huge ball at the center? Newton agreed that this would indeed be the case if the universe were finite in extent. However, he went on, “if the matter was evenly diffused through an infinite space, it would never convene into one mass but some of it convene into one mass and some into another so as to make an infinite number of great masses scattered at great distances from one to another throughout all that infinite space.” Newton’s belief in the universal nature of gravity was strong enough to let him speculate confidently about the spatial extent of the cosmos as a whole.

Centuries later, Einstein did something similar. He formulated his general theory of relativity in final form in 1915, wherein he went a step beyond Newton and attributed gravity to the curvature of space about a massive body (and time, but let’s leave this aside for now): the larger the mass, the more space is bent around it, like the elastic surface of a trampoline around people of different weights. No more was a mysterious action-at-a-distance called forth to explain how massive bodies tend toward one another: in a curved space trajectories are no longer straight. Of course, Einstein didn’t explain why mass should have this effect on the geometry of space. I suspect that, like Newton, he would have answered that he “feigned no hypothesis.” His theory worked beautifully, explaining things Newton’s couldn’t, as observational tests concerned with solar system dynamics attested. And that was enough.

In 1917, less than two years after the publication of his general theory, Einstein wrote a remarkable paper, “Cosmological Considerations on the General Theory of Relativity.” Like Newton, Einstein extrapolated the validity of his theory beyond the solar system, where it was tested at the time, to the universe as whole, and he proceeded to consider the shape of the entire cosmos. In true Platonist fashion, he wanted the cosmos to have the most perfect of shapes, that of a sphere. For convenience, and because of the lack of any opposing observation at the time, he also wanted the universe to be static. His equations produced the desired answer—a static and spherically symmetric Universe—but with a hidden surprise: in order to avoid the total collapse of matter to a central point (which would occur, just as Bentley had worried in Newton’s case), Einstein refrained from making space infinite in extent. Instead, he introduced what he called a “universal constant” and added a new term to the equations describing the curvature of space, noting that, if sufficiently small, this constant was “also compatible with the facts of experience derived from the solar system.” This constant, “not justified by our actual knowledge of gravitation,” he conceded, is now called the “cosmological constant” and may indeed play a key role in the dynamics of the cosmos, although one quite different from that which Einstein had prescribed. Einstein needed it to ensure that his static spherical universe would not collapse onto itself. Displaying complete faith in his theory, he not only extrapolated his equations from the solar system to the entire universe but also imposed on his theory of the cosmos the effects of a strange repulsion whose job was to balance the cosmic dome.

To go beyond the known, both Newton and Einstein had to take intellectual risks, making assumptions based on intuition and personal prejudice. That they did so, knowing that their speculative theories were necessarily faulty and limited, illustrates the power of belief in the creative process of two of the greatest scientists of all time. To a greater or lesser extent, every person engaged in the advancement of knowledge does the same.

Beyond Space and Time
(Wherein we explore how different religions have faced the question of the origin of all things)

Backtrack ten thousand years, to just before the dawn of the first great civilizations along the Tigris and the Euphrates Rivers, where Iraq is now. To divinize Nature was an attempt to have a certain measure of control over what was uncontrollable. Floods, droughts, earthquakes, volcanoes, tidal waves—what even today insurance companies (shamelessly) call “acts of God”—were attributed to angry gods who needed to be placated. A language had to be developed, a common dialect between human and deity, enacted through ritualistic practices and mythic narratives, to bridge the enormous power imbalance between humans and the forces of Nature. As threats to survival came from everywhere—within the Earth, from its surface, and from the skies—gods had to be everywhere as well. Religion was born of necessity and reverence. Quite possibly, any thinking being with widespread but limited powers must assume the existence of other beings, be they gods or, more recently, aliens, with powers beyond his. The alternative, to leave natural disasters to chance, was just too scary to contemplate, as it would imply in accepting humankind’s helplessness and utter loneliness in confronting the unknown. To have a fighting chance to control their destiny, humans had to believe.

Fear was not the only driving force toward belief, although it was possibly the main one. But not everything was bad. Good things also happened: a good crop, a productive hunt, quiet weather, bountiful oceans. Nature didn’t only take away; it also gave plenty. In its dual role as giver and taker, it kept people alive, and it could kill them. Reflecting this polar tension, natural phenomena could be regular and safe—the day-night cycle, the seasons, the phases of the Moon, the tides—or irregular and fearsome, as in solar eclipses, comets, avalanches, and forest fires. It is then not surprising that regularity was (and is) associated with good and irregularity with bad: natural phenomena gained a moral dimension that, through the divinization of Nature, reflected directly the whims of intangible gods.

Across the world, ancient cultures erected monuments and temples to celebrate and to clock the regularity of the heavens. In England, Stonehenge’s function as a burial place is probably related to the yearly alignment of the “Heel Stone” with the rising Sun during summer solstice, establishing a link between the periodic return of the Sun and the human’s cycle of life and death. If the mechanisms behind the cyclic motions in the heavens were unknown—and there was no desire to “know” them, at least in the way we understand knowing now—they were still noted and in some cases measured with great care. Some three thousand years ago, the Babylonians, for example, had a well-established astronomical tradition, reflected in their creation myth, the Enuma Elish (“When Above”). They made detailed tables mapping the motions of the planets and the Moon across the sky, and registered any observed periodicities, as in the Ammisaduqa tablet, which recorded the risings and settings of Venus for twenty-one years.

There is comfort in repetition. If Nature beats to a drum, perhaps we do too. A cyclic time brings with it the promise of rebirth, establishing a deep connection between human and cosmos: our existence reflects that of the whole world. No wonder the myth of the eternal return resonates with so many cultures. What could be better than to believe that we return over and over again, that death is not the end but a transition to a new beginning?

As a father of five, I see this struggle with endings in all my children. My son Lucian, who was six when I wrote these lines, has been obsessed with death since he was four. Death sounds like an absurdity when time seems endless. “What happens after we die?” is one of those questions every parent hears, and most struggle to answer. Lucian is convinced that we return. He is just not quite sure if we return the same or as a different person. His choice, of course, is to come back the same, with the same parents and siblings, essentially reliving life twice or, better still, endlessly. What could be safer than not to have to face loss? It breaks my heart to have to tell him that what happens to us is the same thing that happens to the ant he crushes under his feet. He, of course, is not convinced. “How do you know, Dad?” “I don’t know for sure, son. Some people believe we do come back; others that we go to a place called Paradise, where we meet everybody else who has died. The problem is that I haven’t heard back from any of them to be sure that that’s where we are headed.” The conversation usually ends with a very tight hug and many utterings of “I love you.” What could be harder than to know that I cannot love him forever? And that one day, in the normal course of things, he will have to cope with my death?

With the advent of the Abrahamic faiths, a radically different way to think about the nature of time made a triumphal entrance: instead of ongoing cycles of creation and destruction, of life and death, time becomes linear, with a single beginning and an end. “Profane history,” as Eliade called it, is what happens between birth and death. The stakes suddenly became much higher, since with a single lifetime there is only one chance to be happy. For Christians and Muslims, the notion of an after-death Paradise comes to the rescue, and time begets a dual role, linear in life and inexistent in Paradise.

Linear or cyclic, time has always been a measure of transformation. Follow it to the future; it leads to endings. Follow it to the past; it leads to beginnings. In mythic narratives, humans are always subjected to the changes that time brings, while gods live outside time, never aging or getting sick. As life begets life, and generations succeed one another, following time backwards will necessarily lead to first life, the first living thing, be it bacteria, human, or beast. It is here the key question arises: How did the first living creature emerge, if there was nothing already living to give it birth? The same reasoning can be extrapolated to the world: How did the world come to be, if it had a beginning? The mythic answer, in the vast majority of cases, is clear: gods created the world first and then life. Only that which exists without time can first create that which exists within time. Although some creation myths, most notably among the Maori of New Zealand, suggest that the first creation could have happened without the interference of gods, in most myths time itself becomes a creation, starting once the world comes into being, as Saint Augustine cleverly proposed in The Confessions (Book 11, Chapter 13):

Seeing then Thou art the Creator of all times, if any time was before Thou madest heaven and earth, why say they that Thou didst forego working? For that very time didst Thou make, nor could times pass by, before Thou madest those times. But if before heaven and earth there was no time, why is it demanded, what Thou then didst? For there was no “then,” when there was no time.

The origin of the world and the beginning of time are thus deeply enmeshed with the nature of the heavens, a connection that remains true in our time as modern cosmological models attempt to describe the origin of the Universe and astrophysicists study the origin of stars and planets. Not surprisingly, as I have examined in my book The Dancing Universe, both cyclic and linear notions of time reappeared in modern cosmology. More surprisingly, an essential characteristic of ancient creation myths—the deep relation between human and cosmos—also returns with current astronomical thought, after a long post-Copernican hiatus when our existence played second fiddle to the material splendor of the Universe. When Copernicus and, more pointedly, Johannes Kepler and Galileo Galilei displaced Earth from the epicenter of Creation during the first decades of the seventeenth century, we lost our special status to become mere inhabitants of one among countless many worlds. Four hundred years later, as the ongoing search for life in the Universe reveals the fragility and relative scarcity of Earthlike planets, life and, more crucially, the uniqueness of human life is regaining its cosmic relevance: we matter because we are rare. The many steps from nonlife to life and then to complex multicellular life are hard to duplicate. Furthermore, the many particulars depend on our planet’s detailed history. However, even with the current lack of evidence we cannot establish conclusively that other kinds of intelligent life don’t exist in the Universe. They may or may not be out there. But what we can do is to state with confidence that if intelligent aliens exist, they are distant and rare. (Or, if ubiquitous, they certainly know how to hide extremely well, something we will get to at the end of this book.) In effect we are alone and must learn to live with our cosmic loneliness.

The urge to know our origins and our place in the cosmos is a defining part of our humanity. Creation myths of all ages ask questions not so different from those scientists ask today, when they ponder the quantum creation of the Universe “out of nothing,” or whether our Universe is but one among countless others, all of them exhalations of a timeless multiverse. The specifics of the questions and of the answers are, of course, entirely different, but not the motivation: to understand where we came from and what our cosmic role is, if any. To the authors of those myths, ultimate questions of origins were solely answerable through invocations of the sacred, as only the timeless could create that which exists within time. To those who do not believe that answers to such questions remain exclusively within the realm of the sacred, the challenge is to scrutinize the reach of our rational explanations of the world and examine how far they can go in making sense of reality and, by extension, of ultimate questions of origins.

Excerpted with permission from "The Island of Knowledge: The Limits of Science and the Search for Meaning" by Marcelo Gleiser. Available from Basic Books, a member of The Perseus Books Group. Copyright © 2014.

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