Finding meaning in an accidental universe
Physicist Alan Lightman on an infinite universe and the big questions about our place in it
*Originally published on March 15, 2022.
Alan Lightman is a physicist who has made significant contributions to science's understanding of gravity and black holes. But as his current job title suggests — Professor of the Practice of Humanities at the Massachusetts Institute of Technology — his intellectual pursuits range far and wide beyond physics.
The answers are elusive, and when they do come, they're not always satisfying. But even then, Lightman finds wonder and something like the sacred in the complexity, splendour and vastness of life and the universe.
Following the publication of his latest book, Probable Impossibilities: Musings on Beginnings and Endings, Lightman spoke with IDEAS producer Chris Wodskou about the universe and our place in it — and matters infinitely big and (almost) infinitely small.
One of the main characters in the new book is Blaise Pascal, the 17th century French philosopher, scientist, mathematician and polymath. What intrigues you so much about him and his writing about the infinite? The infinitely big and the infinitely small?
I was intrigued by his imagination because at the time that he was living, in the early 17th century, the microscope had just been recently invented. And there was very little knowledge of things smaller than a cell, a biological cell, and on the other end of the scale, the furthest distance was the distance to the Sun. And yet he imagined that space extended infinitely far. And he imagined that that also you could go to the infinitely small — you keep subdividing space or matter into smaller and smaller pieces, and that would continue indefinitely.
Tell me about the infinitely big — as science knows or conceives of it today.
What about the other end of the scale, the infinitely small?
Our giant atom smashers can probe the small world down to about one-tenth of one percent of the size of a nucleus of an atom. Of course, we think that there are things smaller than that. But if we keep going to smaller and smaller scales, smaller and smaller sizes, there is a fundamental limit of smallness beyond which we cannot go. And that is called a Planck scale named after the great physicist Max Planck, who was one of the founders of quantum physics. Time and space as we understand it dissolve at the Planck scale, so it doesn't make any sense to talk about space smaller than the Planck scale. Of course, Pascal didn't know any of this in 1650 when he speculated on the infinitely large and evidently small.
The question of our origins is obviously something that science, philosophy, mythology and religion have all grappled with. The first verse of the Gospel According to St. John goes, "In the beginning was the Word, and the Word was with God and the Word was God. How would you complete the sentence, "In the beginning was…."?
I would say in the beginning was quantum physics and relativity. So that probably doesn't sound very spiritual, but to a scientist, it is spiritual. We have very good evidence that our universe began about 13.8 billion years ago in a state of extremely high density and high temperature. But there had to be something before that. And I believe, and most physicists believe, that some kind of space and time existed before the Big Bang.
We speculate that out of that quantum foam of space-time that has probably always existed, that new universes are constantly coming into being and disappearing, coming into being and disappearing. We know that you can create matter out of energy because we've done that in our particle accelerators. And near the Big Bang, our entire universe was the size of a subatomic particle. So it's very conceivable and imaginable that some form of space and time have always existed, that new universes are constantly coming into being. One of those universes became our universe.
I've heard Earth referred to as the "Goldilocks Planet," or we're in the "Goldilocks universe," because things are just right for life to appear. Some people say, "Okay, well, that proves that there's an intelligent designer." And then others, like Stephen Hawking, have said, "No, quantum physics can do this all on its own — we don't need a creator." So when you think about the crusades of some of the more vocal atheist scientists, what do you make of their efforts to disprove the existence of God through science?
I don't think that science can ever disprove the existence of God. And I don't think that religion can ever prove the existence of God. I think that you have to take the existence of God as a matter of faith. What I object to with [Richard] Dawkins and a few of the other so-called neo atheists is their dismissal of believers, their condescension to believers, and I think Dawkins said that believers are stupid and that religion is nonsense. Well, I don't think that Mahatma Gandhi was stupid, and I don't think that Abraham Lincoln was stupid. So I really find that kind of viewpoint offensive. As understood by most religions, God exists outside of time and space. And so you're on a fool's errand to try to use science, which is limited to time and space, to try to disprove or dismiss or undermine something that exists outside of time and space.
I want to pick up on another thing you said when you were talking about the almost randomness of living in a universe, let alone a planet, that is capable of sustaining life. And you use the phrase, in fact, it's the title of your book — The Accidental Universe. What does it mean to live in an accidental universe, one that just kind of came about by chance?
The physicist Steven Weinberg, who died recently in the last few months, a Nobel Prize-winning physicist wrote a little book called The First Three Minutes. And the book was for the layperson, and it was about the first few minutes of our universe and what was happening then. And near the end of the book, he makes the statement, the more we understand about the universe, the more it seems pointless.
It does raise the question, and of course this question comes up not only in physics, but in life: What is the point of it all? What does it all mean, if anything?
So just to expand upon or draw upon that, what you were talking about is a little bit of a form of existentialism. We have to get meaning to everything ourselves because the universe isn't going to give it to us. So do you feel that life can indeed be a very fluky thing, a random thing and therefore not something with great inherent meaning, but at the same time, the fact that we exist, the fact that this happened makes it all the more miraculous and precious?
I think you could still say that matter in living form is very rare in our universe. It's rare in both time and space. You need a very special arrangement of atoms and molecules to make life. And if you extrapolate from the fraction of material on our planet that is in living form, and you extrapolate that to the rest of the universe, you conclude that only about one billionth of one billionth of all the material in the universe is in living form. It's like a few grains of sand in the Gobi Desert. So to me, that sort of forms a bond or a kinship with all other living beings in our universe that even though we probably will never meet each other. That we living beings are in that tiny fraction of material that's in living form. We are the only mechanism by which the universe can witness itself, can observe itself. We are the spectators. We have a special role in the universe.
* This episode was produced by Chris Wodskou. This conversation has been edited for length and clarity.