“If we ever reach the point where we think we thoroughly understand who we are and where we came from,” Carl Sagan wrote in his timeless meditation on science and religion, “we will have failed.” It’s a sentiment that dismisses in one fell Saganesque swoop both the blind dogmatism of religion and the vain certitude of science — a sentiment articulated by some of history’s greatest minds, from Einstein to Ada Lovelace to Isaac Asimov, all the way back to Galileo, and one that Sagan echoed a decade later, three months before his death, writing: “The notion that science and spirituality are somehow mutually exclusive does a disservice to both.” Yet centuries after Galileo and decades after Sagan, humanity remains profoundly uneasy about reconciling these conflicting frameworks for understanding the universe and our place in it.

That vital discomfort is precisely what physicist Alan Lightman — celebrated author of both nonfiction and novels, one of the finest science essayists writing today, the very first person to receive dual appointments in science and the humanities at MIT, an extraordinary storyteller, and one of my favorite minds — explores in one of the essays in his entrancing new anthology, The Accidental Universe: The World You Thought You Knew (public library | IndieBound).

In the foreword, Lightman recounts attending a lecture by the Dalai Lama at MIT, “one of the world’s spiritual leaders sitting cross-legged in a modern temple of science,” and hearing about the Buddhist concept of sunyata, translated as “emptiness” — the notion that objects in the physical universe are vacant of inherent meaning and that we imbue them with meaning and value with the thoughts of our own minds. From this, Lightman argues while adding to history’s finest definitions of science, arises a central challenge of the human condition:

As a scientist, I firmly believe that atoms and molecules are real (even if mostly empty space) and exist independently of our minds. On the other hand, I have witnessed firsthand how distressed I become when I experience anger or jealousy or insult, all emotional states manufactured by my own mind. The mind is certainly its own cosmos. As Milton wrote in Paradise Lost, “[The mind] can make a heaven of hell or a hell of heaven.” In our constant search for meaning in this baffling and temporary existence, trapped as we are within our three pounds of neurons, it is sometimes hard to tell what is real. We often invent what isn’t there. Or ignore what is. We try to impose order, both in our minds and in our conceptions of external reality. We try to connect. We try to find truth. We dream and we hope. And underneath all of these strivings, we are haunted by the suspicion that what we see and understand of the world is only a tiny piece of the whole. […] Science does not reveal the meaning of our existence, but it does draw back some of the veils.

This tension between internal and external reality is also what lies at the root of the age-old tension between science and religion. In one of the best essays in the collection, titled “The Spiritual Universe,” Lightman sets out to lift the veil of this immutable inquiry. He cites a discussion that took place at a monthly gathering of scientists and artists at MIT, aimed at exploring the interplay of science and art, wherein a playwright proposed that science is the religion of our century. Lightman considers the inherent challenges to this notion:

If science is the religion of the twenty-first century, why do we still seriously discuss heaven and hell, life after death, and the manifestations of God? Physicist Alan Guth, another member of our salon, pioneered the inflation version of the Big Bang theory and has helped extend the scientific understanding of the infant universe back to a trillionth of a trillionth of a trillionth of a second after t = 0. A former member, biologist Nancy Hopkins, manipulates the DNA of organisms to study how genes control the development and growth of living creatures. Hasn’t modern science now pushed God into such a tiny corner that He or She or It no longer has any room to operate—or perhaps has been rendered irrelevant altogether? Not according to surveys showing that more than three-quarters of Americans believe in miracles, eternal souls, and God. Despite the recent spate of books and pronouncements by prominent atheists, religion remains, along with science, one of the dominant forces that shape our civilization. Our little group of scientists and artists finds itself fascinated with these contrasting beliefs, fascinated with different ways of understanding the world. And fascinated by how science and religion can coexist in our minds.

As a scientist and self-professed humanist himself, Lightman exorcises his lifelong struggle to reconcile these conflicting worldviews by proposing a set of criteria for the kind of religious belief that would be compatible with rather than contradictory to science:

The first step in this journey is to state what I will call the central doctrine of science: All properties and events in the physical universe are governed by laws, and those laws are true at every time and place in the universe. Although scientists do not talk explicitly about this doctrine, and my doctoral thesis adviser never mentioned it once to his graduate students, the central doctrine is the invisible oxygen that most scientists breathe. We do not, of course, know all the fundamental laws at the present time. But most scientists believe that a complete set of such laws exists and, in principle, that it is discoverable by human beings, just as nineteenth-century explorers believed in the North Pole although no one had yet reached it. […] Next, a working definition of God. I would not pretend to know the nature of God, if God does indeed exist, but for the purposes of this discussion, and in agreement with almost all religions, I think we can safely say that God is understood to be a Being not restricted by the laws that govern matter and energy in the physical universe. In other words, God exists outside matter and energy. In most religions, this Being acts with purpose and will, sometimes violating existing physical law (that is, performing miracles), and has additional qualities such as intelligence, compassion, and omniscience. Starting with these axioms, we can say that science and God are compatible as long as the latter is content to stand on the sidelines once the universe has begun. A God that intervenes after the cosmic pendulum has been set into motion, violating the physical laws, would clearly upend the central doctrine of science. Of course, the physical laws could have been created by God before the beginning of time. But once created, according to the central doctrine, the laws are immutable and cannot be violated from one moment to the next.

With these criteria in mind, he offers a taxonomy of religious beliefs, based on the degree of control they assign to their highest deity: At the extreme end, denying the existence of a God, is atheism; up the sliding scale of faith is deism, whose God created the universe but has not interfered since that initial spark — a favorite model in the 17th and 18th centuries, with such prominent proponents as Voltaire; then comes immanentism with yet more divine intervention, which holds that God created the physical universe and its laws, and continues to propel it but only through the stringent and consistent application of these permanent laws; at the other extreme end, opposite atheism, is interventionism — God created the universe and its laws, and can occasionally interfere with their predictable function to produce unpredictable results, commonly called miracles. Because most major religions — including Christianity, Judaism, Islam, and Hinduism — are built upon an interventionist view of God, Lightman points out that they are incompatible with science and observes the logical conclusion:

Except for a God who sits down after the universe begins, all other Gods conflict with the assumptions of science.

The situation is further muddled by the fact that the majority of laypeople who are both religious and understand the value of science don’t subscribe to its central doctrine — that same logical foundation that renders an interventionist God impossible. Lightman cites a sociological study which found that 25% of scientists at elite American universities believe in the existence of God and don’t consider science the only framework for explaining the world. Lightman, who considers himself an atheist, illustrates the conundrum with his own beliefs and points to the humanities — that essential anchor of the human experience — as the spiritual complement to science:

I completely endorse the central doctrine of science. And I do not believe in the existence of a Being who lives beyond matter and energy, even if that Being refrains from entering the fray of the physical world. However, I certainly agree with [such scientists] that science is not the only avenue for arriving at knowledge, that there are interesting and vital questions beyond the reach of test tubes and equations. Obviously, vast territories of the arts concern inner experiences that cannot be analyzed by science. The humanities, such as history and philosophy, raise questions that do not have definite or unanimously accepted answers.

This is where Lightman’s exquisite touch as both an essayist and a humanist springs so vibrantly alive:

There are things we take on faith, without physical proof and even sometimes without any methodology for proof. We cannot clearly show why the ending of a particular novel haunts us. We cannot prove under what conditions we would sacrifice our own life in order to save the life of our child. We cannot prove whether it is right or wrong to steal in order to feed our family, or even agree on a definition of “right” and “wrong.” We cannot prove the meaning of our life, or whether life has any meaning at all. For these questions, we can gather evidence and debate, but in the end we cannot arrive at any system of analysis akin to the way in which a physicist decides how many seconds it will take a one-foot-long pendulum to make a complete swing. The previous questions are questions of aesthetics, morality, philosophy. These are questions for the arts and the humanities. These are also questions aligned with some of the intangible concerns of traditional religion.

Reflecting on his early days as a physics grad student, where he was taught that the concept of a “well-posed problem” — a question stated so clearly that it would guarantee an answer — he turns to Rilke’s famous wisdom and considers both the difference and the margin of complement between art and science:

At any moment in time, every scientist is working on, or attempting to work on, a well-posed problem, a question with a definite answer. We scientists are taught from an early stage of our apprenticeship not to waste time on questions that do not have clear and definite answers. But artists and humanists often don’t care what the answer is because definite answers don’t exist to all interesting and important questions. Ideas in a novel or emotion in a symphony are complicated with the intrinsic ambiguity of human nature. … For many artists and humanists, the question is more important than the answer. As the German poet Rainer Maria Rilke wrote a century ago, “We should try to love the questions themselves, like locked rooms and like books that are written in a very foreign tongue. Then there are also the questions that have definite answers but which we cannot answer. The question of the existence of God may be such a question. As human beings, don’t we need questions without answers as well as questions with answers?

Indeed, this tolerance for the unanswered — and possibly the unanswerable — is not only at the heart of creativity and the secret of happiness, but also, Lightman argues, the essence of faith:

Faith, in its broadest sense, is about far more than belief in the existence of God or the disregard of scientific evidence. Faith is the willingness to give ourselves over, at times, to things we do not fully understand. Faith is the belief in things larger than ourselves. Faith is the ability to honor stillness at some moments and at others to ride the passion and exuberance that is the artistic impulse, the flight of the imagination, the full engagement with this strange and shimmering world.

Once again, Lightman envelops us in his enchanting storytelling to make this point as dimensional as it is when it manifests in life: He tells the story of a family of ospreys that nested near his home in Maine for many years, arriving from South America each spring to lay eggs, then raising their babies until the little ones took their first flight in late summer. Lightman and his wife recorded these cycles of life obsessively year after year in their “osprey journals” filled with notes, photographs, and lovingly collected data on that “small part of the universe.” But while Lightman might describe himself as a humanist, this final anecdote exposes him as a true “creaturist” who lives with remarkable respect for non-human beings and our shared existence:

One August afternoon, the two baby ospreys of that season took flight for the first time as I stood on the circular deck of my house watching the nest. All summer long, they had watched me on that deck as I watched them. To them, it must have looked like I was in my nest just as they were in theirs. On this particular afternoon, their maiden flight, they did a loop of my house and then headed straight at me with tremendous speed. My immediate impulse was to run for cover, since they could have ripped me apart with their powerful talons. But something held me to my ground. When they were within twenty feet of me, they suddenly veered upward and away. But before that dazzling and frightening vertical climb, for about half a second we made eye contact. Words cannot convey what was exchanged between us in that instant. It was a look of connectedness, of mutual respect, of recognition that we shared the same land. After they were gone, I found that I was shaking, and in tears. To this day, I do not understand what happened in that half second. But it was one of the most profound moments of my life.

Lightman closes the chapter with a beautiful meditation on where all of this leaves us:

Some people believe that there is no distinction between the spiritual and physical universes, no distinction between the inner and the outer, between the subjective and the objective, between the miraculous and the rational. I need such distinctions to make sense of my spiritual and scientific lives. For me, there is room for both a spiritual universe and a physical universe, just as there is room for both religion and science. Each universe has its own power. Each has its own beauty, and mystery. A Presbyterian minister recently said to me that science and religion share a sense of wonder. I agree.

The Accidental Universe is a sublime, mind-bending, soul-expanding read in its entirety, exploring such magnificent mysteries of our world and the cosmos as dark matter, multiverses, and the arrow of time, all considered through the dimensional lens of a mind at once voracious for knowledge and at peace with the unknown. Complement it with Dorion Sagan, son of Carl, on why science and philosophy need each other.