This post was adapted from a talk by Dr. Alan Lightman called Fact and Faith: A Meditation on Science and Religion, organized and moderated by Sinai and Synapses Fellow Adam Reynolds as part of the MIT Addir Fellows Interfaith Dialogue, a yearlong program where MIT students (graduate and undergraduate) meet weekly for interfaith dialogue. You can listen to the full lecture, with Q&A, above.

Hi, good evening. Thanks for being here, it’s wonderful to see all of you. My name’s Adam Reynolds, I’m one of the chaplains at MIT. I want to introduce our speaker and before I do that, I’m going to say a little bit about the organization that is hosting this event, which is the Addir Fellows Interfaith dialogue. Addir is a word that means bridge in Ancient Sumerian, and our interfaith program is about building bridges. And we have something called the Addir Fellows, which is a fellowship that MIT students, undergrad and grad, can apply for, and then become part of a yearlong cohort that does weekly interfaith dialogue. I’m a huge fan of this program, because I get to watch the relationships that form, sometimes across multiple dimensions of difference. And seeing those relationships and the interfaith learning that takes place across those I think is really important, and something our world needs more of right now.

We are so fortunate at MIT that Professor Lightman calls us home, and we’re very excited to have him here tonight. So without further ado, Alan Lightman.

Alan Lightman: My talk to you tonight is based on a new book of mine called Searching for Stars On an Island in Maine. And the subject of the book is broadly science and religion, which is a confluence I’ve been interested in for many years. For many years, my wife and I have spent our summers on an island in Maine. And it’s a small island, only about 30 acres, and there are six families who live on the island. There are no boats or ferries that go to the island, no bridges, so everybody on the island, the six families, has their own boat.

So my story concerns a particular night that I was coming back to the island in my boat. It was very late at night, after midnight, and I was alone, and I took a chance and turned off the running lights of the boat. And it was already a dark night, and the sky was just brilliant with stars, and it got even darker. And I turned off the running lights, and then I took another chance and I turned off the engine of the boat. And it got very quiet. So I lay down in the boat and looked up at the sky, and I found myself falling into infinity. I lost all track of my self, my body, and after a while, I felt like all of time, from the far distant past, long before I was born, to the far distant future, long after I would be dead, was compressed to a dot. I felt like I was connected – not only to the stars, but to the entire cosmos. And I felt that I was merging with something far bigger than myself, some permanent thing, some unity. After a time, I sat up and started the engine again the boat and I had no idea how long I had been lying there.

Well, as Adam said, I’ve worked as a physicist for many years, and I’ve always had a purely scientific view of the world. And by that, I mean that I have always believed that the world is made completely of material and nothing more, that everything in the universe is governed by a small number of laws and that humans and stars and everything else made out of material will eventually disintegrate and pass away.

And I remember even, at the age of 12 or 13, I was impressed by the logic and the materiality of the world. I had my own laboratory, and among other projects, I built a pendulum by attaching a fishing wire to a string, and I read in Popular Science that the time for the pendulum to complete a swing, the period, was proportional to the square root of the length of the string. And so I took out a ruler and a stopwatch, and I tested this wonderful law. And as far as I could tell, everything was logic and pattern. Everything was subject to quantitative tests, and I saw no reason to believe in a supernatural being or the supernatural world.

But after that experience in the boat many years later, I understood the powerful attraction of the ethereal and the non-material, things that are all-encompassing, things that feel much bigger than us, things that have some kind of eternity. Things that don’t change. Things that are not reducible to logical analysis. And at the same time, perhaps paradoxically, I remained a scientist. I remained committed to the material world. And I’m still committed to the material world.

Science and religion differ profoundly in the way the truths are discovered. In religion and theology, those truths and beliefs seem to have two origins. First there are the sacred books, like the Bible and the Qur’an and the Vedas and the Pali Canon. Believers have faith that these books contain the true Word of God or other enlightened beings. And if so, the authority of the teachings in those books comes from the infinite wisdom of those enlightened beings.

The second origin of religious and spiritual truth is more personal – what one might call the transcendent experience. The experience I had in the boat in Maine was a transcendent experience, and I’m sure all of you have had transcendent experiences as well, so I wanted to talk briefly about these two kinds of knowledge and religion and theology, and then I’ll talk about the kind of knowledge we have in science.

Quotations from the sacred books are used to declare truths ranging from the origin of the universe, to proper moral behavior, to the details of reproductive biology. Still today, many religious thinkers attribute absolute authority and truth to the teaching of the sacred books. It’s called divine revelation.  I wanted to read you a sentence from the Second Vatican Council’s Dogmatic Constitution on Divine Revelation, endorsed by Pope Paul VI: “the books of scripture must be acknowledged as teaching solidly, faithfully, and without error, that truth which God want to put into sacred writings.”

So I’m somewhere personally between an atheist and agnostic. I completely respect the notions of God and of other divine beings. However, I do insist on one thing. I insist that any statements made by such beings about the material world must be subject to the experimental testing of science. In my view, the truth of such statements about the material world cannot be assumed, they have to be tested and revised or rejected as needed. The spiritual world has its own domain. The physical world should be the domain of science. And in the physical world, the laws of science can’t apply sometimes and not other times, or in some places and not other places. It’s not okay with me if the principle of aerodynamics works on some of my airplane flights and not on others.

So let me turn to the transcendent experience now, which is what I consider to be the second kind of knowledge that religion and theology give to us. And for me, as both a scientist and as a humanist, the transcendent experience is the most powerful evidence we have for a spiritual world. And by transcendent experience, what I mean is the immediate and vital feeling of being connected to something larger than ourselves, and the feeling that there is some unseen order in the universe. And by spiritual universe, I mean the totality of all of these experiences and the feelings that they evoke. And as I said before, I’m sure that all of you have had transcendent experiences. Maybe not laying on your back looking at the stars, but different kinds of experiences.

The transcendent experience as an avenue to truth is a deeply human path to truth. And in fact, some philosophers and theologians believe that truth exists only in the realm of humanity and the human mind. And such a belief, of course, runs head-on against the beliefs in science, where in science we believe that there is a reality and a truth outside out there that’s independent of our minds. Doesn’t the parabolic arc of a tossed stone exist whether or not a human mind conceives such a curve?

These opposing views of whether truth could exist only within the human mind or outside the human mind were highlighted in an extraordinary conversation between Einstein and the great Indian poet Tagore. Tagore and Einstein admired each other tremendously, and they arranged to meet on July 14th, 1930 at Einstein’s home in Caputh, which is near Berlin. And I want to give you just a portion of their conversation, which I think is just extraordinary. The discussion ends with Einstein saying “the problem begins with whether truth is independent of our consciousness.” And Tagore replies: “what we call truth lies in the rational harmony between subjective and objective of aspects of reality.”

I would say that there are basically two kinds of knowledge in science. There’s knowledge of the properties of material objects, like the size and the mass of a rain drop, and there’s knowledge, the second kind, what we call the laws of nature.

One of the first human beings to formulate a law of nature, a law of the physical world, was Archimedes more than 2000 years ago. Archimedes’ Law of Floating Bodies says  “Any solid lighter than a fluid will when placed in the fluid be so far immersed that the weight of the solid will be equal to the weight of the fluid displaced.” So we can speculate on how Archimedes arrived at that law. There were certainly scales and balances 2000 years ago for trade in the marketplace, so you could take an object, put it on a scale, and weigh it, then you could take a rectangular pan of water, put the object in the water, see how many centimeters  the water rose. You multiply it out by the area of the base, and you get the volume of water displaced, and then you take that volume of water and you put it on your scale, and you weigh that. And undoubtedly, Archimedes would have done this over and over and over again to convince himself that the law was accurate. He also would have used different liquids besides water, for example, mercury, to show the generality of the law.

And as you know, all of the laws that we have in science are like Archimedes’ law. The laws are precise. They’re quantitative, they’re general and it’s really in some ways astonishing that nature obeys these laws at all. On the other hand, I think that maybe you couldn’t build a universe at all, unless it had that kind of self-consistency that the laws bring. A universe without laws would be like 2 + 2 = 4 and 2+ 2 = 3, both at the same time. I think that the universe couldn’t exist. And over the last couple of hundred years, as you know, as we’ve made all these discoveries, we’ve seen no evidence to contradict the notion that all phenomena in the physical world obey laws.

Galileo’s law of falling bodies, which I discovered at 12 or 13, was later found to be a special case of Newton’s law of gravity. Newton’s law worked beautifully for a couple of hundred years, and then the mid 19th century we found that it was a little bit off for the orbit of the planet Mercury, even though it still made great predictions. And then in 1915 Albert Einstein came up with his theory of general relativity, his new theory of gravity, which correctly predicted the orbit of Mercury and many other phenomena. One of the things it predicted was gravitational waves, and of course, just this past year, Rainer Weiss of MIT would share the Nobel Prize for detecting gravitational waves.

Now here is the important point. Despite its fantastic success, we know that even Einstein’s theory of gravity is going to be revised like Newton’s theory was going to be revised, because Einstein’s theory does not include quantum physics. And this is the way that science works. There’s a constant process of revision in science. Everything that we know in science is provisional. Everything, every law, that we believe now is an approximation to a deeper law. And in fact, what we call the laws of nature that we understand should be called the approximate laws of nature. That’s what science is about, getting better and better approximations.

And it’s in this process of revision that we see the strongest differences between the methods of science and the methods of religion. As I just mentioned, everything that we know in science is provisional and subject to provision, everything has to be tested and proved. On the other hand, the knowledge of religion, coming either from the divine authority of the sacred books or from the personal transcendent experience, is not subject to revision. It’s not an approximation. It’s certain. And to me, it’s sort of paradoxical that everything that we know in science is uncertain and everything that we know in religion is certain, in the sense that I have just described it. Of course, the uncertainties and approximations of science and have been good enough to bring us smartphones and antibiotics and landing people on the moon, so science is not doing badly with these approximations and uncertainties. But still, there’s this fundamental distinction between the two.

As I’ve said, science demands proof for what it believes. But there is something that scientists believe without proof, and that cannot be proved, and it’s something I call the central doctrine of science. This is basically the belief that everything in the physical world obeys laws, and those laws are the same everywhere in the universe. When I was a graduate student in physics, I sort of learned the central doctrine of science by osmosis. It was just assumed. It wasn’t even stated explicitly. It’s the assumption in which we do all of our calculations. And I call it a doctrine because, despite its success in the past, the central doctrine of science cannot be proved. No matter how lawful and logical the physical world has been up until now, we can’t be certain that there wouldn’t be some phenomenon that happens tomorrow that is completely unlawful and unexplainable by science. We can’t be certain of that. We have such faith, we scientists have such faith in the central doctrine, that when we find physical phenomena that cannot be explained in terms of known laws, instead of giving up on a lawful universe, we have attempted revise the laws.

And that’s what happened with the the perihelion shift of Mercury, that when scientists couldn’t explain the discrepancy with Newton’s theory, they didn’t think, “well, maybe there was some act of God or there’s some miracle going on, or something intrinsically unexplainable.” They just thought “well we need a better theory.” And I can’t imagine any event in the material world that would cause a scientist to label it as a miracle. Even if this lectern began floating in the air right now, scientists would look for magnetic levitators, or they would think, “well, there’s some force that we haven’t yet discovered but, but a natural force, not a supernatural force.” I can’t explain to you how strongly it is that scientists are committed to the central doctrine of science.

There’s another belief in science that cannot be proven and it’s related. And that is our belief that there is a final theory. Steven Weinberg, the Nobel Prize winning physicist who was a professor at MIT here before he went to the University of Texas, wrote a whole book called Dreams of a Final Theory. A final theory would be a theory that was not an approximation to a deeper one  – an ultimate theory, perfect, from which, in principle, you could calculate anything in the universe without approximation. The irony there is that even if we had a final theory, we would never be able to prove that it was the final theory, or know that we were in possession of it, because as I said, with the central doctrine of science, you could never be certain that tomorrow there might not be some phenomena that violated the predictions of the theory. So even if we had it, we wouldn’t know that we had it for sure.

So, we just have to believe that it exists. We have to take it on faith, which is what we do with the central doctrine of science. We take it on faith, whether we are explicit about that or not. Despite the enormous differences in religion and science in the kind of knowledge that they have, in the way that that knowledge is obtained and revised or not revised, they share a degree of faith, a belief and commitment to something that is unprovable.