I look out on the sea of shaved heads and maroon robes. The monks sit on thin mats cross-legged in the plain classroom. The air shimmers with monsoon heat. One young monk puts up his hand. “Is the big bang real?” He asks. I pause before answering. The fact that the universe evolved an early, hot and dense phase is supported by a web of observational evidence. On the other hand, the origin is projected to be smaller than a sub-atomic particle, a state of infinite temperature and density that can’t be understood in any physical theory. “I don’t know,” is my honest answer.

For a decade, I’ve been traveling to the Himalayan foothills to teach Buddhist monks (and more recently, nuns) cosmology. “Science for Monks” was started at the direction of His Holiness the Dalai Lama, who was worried that the Buddhist monastic tradition did not include math and modern science. These monks are Tibetans living in exile in India. Most left Tibet as small children and many will never see their families again. They are diligent and attentive students. Their playful curiosity makes the classroom a place of discovery and wonder.

The concepts of cosmology are mind-bending: dark matter, dark energy, curved space-time, and the big bang. Western scientists tend to concentrate on facts and data and shy away from philosophical questions. Buddhist monks like to home in on the essence of a subject. We often find ourselves addressing the question: Is that real?

The philosopher said: “I only need some paper and a pencil.” The physicist replied: “You win. I need some paper, a pencil, and a wastepaper basket.”

In his book The Universe in a Single Atom, the Dalai Lama posits Buddhism as an empirical tradition, akin to science: “My confidence in venturing into science lies in my basic belief that as in science, so in Buddhism, understanding the nature of reality is pursued by critical investigation: if scientific analysis were to conclusively demonstrate certain claims in Buddhism to be false, then we must accept the claims of science and abandon those claims.” This is a striking assertion, unlikely to come out of the mouth of a leader of any other world religion.

Reality is a challenging concept for both scientists and Buddhists. The modern scientific tradition that starts with Galileo Galilei is based on experiment and observations of the natural world. Models and theories have evolved as they confront data, and sometimes they are overturned completely. The restless nature of science, in a continual process of augmentation and revision, is its essential strength as a system of knowledge.                                                                                

Scientists are acutely aware that our understanding of nature is limited by the tools at our disposal. Human perception is flawed. For example, the apparent solidity of normal matter is an illusion caused by the electrical force within an atom, and the senses only give us access to a minute fraction of the waves and vibrations that permeate the universe. In cosmology, regions of space and time that we can infer to exist may never be observable. In quantum physics, some properties of atoms cannot be simultaneously known with arbitrary precision. More profoundly, quantum entanglement and action at a distance mean that reality at a fixed location is a meaningless concept.

Reality in physics is contingent on corroboration through observation. It can be distinguished from reality as considered by philosophers, a field called ontology. This distinction is neatly encapsulated in the story of an argument between a philosopher and a theoretical physicist over who had lower equipment costs. The philosopher said: “I only need some paper and a pencil.” The physicist replied: “You win. I need some paper, a pencil, and a wastepaper basket.”

Science generally hews to a materialist stance [...] but this worldview can’t yet accommodate subjective human experience.

Buddhism shares with science the tradition of empirical and rational exploration of reality. However, the methods of inquiry are quite distinct. Science generally hews to a materialist stance, where reality consists only of space-time and mass-energy and their emergent properties. This worldview can’t yet accommodate subjective human experience. Buddhism focuses on gaining insight into the reality of suffering, and the possible path to freedom from suffering. As the scholar Alan Wallace has written: “Buddhism is not concerned with the nature of reality as it exists independent of human experience, but rather with the reality of human experience.”

Scientific and Buddhist views of reality are complementary; the former is third-person and the latter is first-person. A scientific materialist might argue that the mysteries of the mind will soon be subject to the language of mathematics. To which, their Buddhist interlocutor might be gently skeptical. Other concepts are mutually reinforcing. In conversation with the monks and nuns in my classroom, their thinking is supple and subtle enough to accommodate the traditions of the East and the West.

Both traditions give a central role to the idea of impermanence. Modern physics describes a constant interplay between mass and energy. Particles can be created from pure energy, and even from the vacuum of space. Buddhism talks of subtle impermanence where there is change at every infinitesimal moment. It describes a universe where there are no solid or distinct entities, only a flow of incessant interactions.

Another theme is interdependence. Gravity is a force with infinite range, and in Mach’s principle the inertia of an object can only be defined in terms of the total mass in the universe. In biology, all living things share the same cosmic genealogy. Similarly, Buddhism holds that nothing can be its own cause, and all things exist only in relationship to others.

Perhaps the richest and most surprising common ground is emptiness. In modern physics, the world is made up not of things but of potentialities. The vacuum is a basis for the creation of particles and antiparticles, and even, in the inflationary paradigm, for the creation of our entire universe. Buddhism describes a middle way between nihilism (nothing exists) and material realism (all things exist). In teachings, the Buddha said that the ultimate nature of reality was emptiness. Emptiness is not nothingness; it is the absence of false qualities projected onto the objects of our experience by ignorance.

I learn that the Buddha described multiple universes that arose out of nothingness and returned to nothingness over vast cosmic cycles of creation.

Outside the classroom, we talk long into the evening, fueled by salty butter tea and tsampa, which is roast barley flour kneaded into a sticky paste. I learn that the Buddha described multiple universes that arose out of nothingness and returned to nothingness over vast cosmic cycles of creation. I learn that the timescale for this evolution was billions or even trillions of years. I learn that countless beings were born in these many universes, each moving through the process of spiritual evolution to a state of perfect wisdom.   

A little later in the course, we’re talking about the two dominant ingredients of the universe: dark matter and dark energy. I see the question coming before the hand goes up: “How do you know they’re real?” I weigh my words. We have lots of evidence that galaxies are held together by something that exerts the force of gravity but does not interact with radiation. Even though we can’t see it, we see the way it bends light, an effect called gravitational lensing that was predicted by general relativity. Science explains many things that are invisible, like electric and magnetic fields. So, we think dark matter really exists even though we don’t know its fundamental physical nature.

As for dark energy, I throw my hands up, literally and metaphorically. Something is causing the cosmic expansion to accelerate. It acts in opposition to gravity and it seems to be a property of the vacuum of space. It’s colorless and odorless, and it can’t be studied in the lab. Something is causing nothing, and so everything, to expand at an ever-increasing rate. We can’t even pretend it’s real. Dark energy is just a term to describe our ignorance.

“The universe is made of stories, not of atoms,” wrote poet Muriel Rukeyser in The Speed of Darkness. The monks and nuns in my class become real to me as they tell stories of escape from Tibet over the ice fields in the depths of winter. Their stories are as real as their atoms. And even their atoms have stories. My atoms and theirs were once compressed into an iota of space-time, part of the coruscating heat of the big bang. The atoms traveled disparate paths for billions of years, through stellar cores, the depths of space, and the vaults of the Earth, before being united in a modest classroom near the roof of the world.