Humans are 'a species in a very rare planet': cosmologist makes the case against existential dread

While some might respond to the vastness of the universe with a sense of existential dread, physicist and cosmologist Marcelo Gleiser takes a different approach, offering up something he calls “human centrism.”

Templeton Prize recipient Marcelo Gleiser says we have a 'moral imperative' to protect life on this planet

Physicist and cosmologist Marcelo Gleiser says he used to look up at the stars as a child and wonder where they came from. 'This sense of belonging to something which is much bigger than we are was very much part of my experience as a child,' he says. (Anthony Anex/Keystone/Associated Press)

Originally published in June 2019.

While some might respond to the vastness of the universe with a sense of existential dread, physicist and cosmologist Marcelo Gleiser takes a different approach, offering up something he calls "human centrism."

He defines it as an "awareness of how important we are in this moment in cosmic history." He explains that "for the first time, we actually have enough knowledge about astronomy, about physics and biology, to understand how precious and how fragile our condition is."

He says this mindset is especially important in an age of climate change and political polarization.

Gleiser's ideas on science, philosophy, and spirituality earned him Templeton Prize last year, an award given to individuals who have "made an exceptional contribution to affirming life's spiritual dimension." Previous recipients include the Dalai Lama, physicist Freeman Dyson, astronomer Martin Rees and Archbishop Desmond Tutu.

Marcelo Gleiser, a professor of physics and astronomy at Dartmouth College, was recently awarded the Templeton Prize. (Trustees of Dartmouth College)

Gleiser spoke about spirituality, science and "human centrism" with Tapestry host Mary Hines. Here is a part of their conversation.

I'm really intrigued by something you said — this idea that to see the shooting stars when you were a little boy at your grandparents' place in Brazil — and being suffused with this feeling of belonging to something bigger. Because some people look at that same sky or try to conceive of how huge the universe is, and it will fill that person with existential dread. "This is too big. I can't wrap my head around it. We are so insignificant." Are those two responses at battle within you? Or is that existential dread something you have never gone near?

You're right that the scientific discourse has traditionally been one where we hear things like, "The more we know about the universe, the less important we become." And this is sort of what we call the Copernican world view, in the sense that Copernicus was the fellow that suggested that the Earth is not the centre of the universe, it's just a planet going around the sun.

He kind of moved us as the centerpiece of creation, so to speak, all the way to the periphery and just another planet. And since him, it's been one insult after another. Because then, of course, the sun is not the centre, it's just another star, and there are 200 billion stars in our galaxy alone. And, of course, our galaxy is just one galaxy of around 200 billion or 300 billion others in the universe. So truly, if you look at that position, and you look at the vastness, the distances, indeed, it looks like we are nothing. And then that is your existential angst. 

I think Carl Sagan called these the "Great Demotions." Then you add the Copernican and the other revolutions to the fact of evolution, our common ancestry with chimpanzees, and it's like, "Well, OK, so we're chopped liver on this little planet. We're at the centre of nothing."

It gets even worse. Chimpanzees are nice. They're kind of almost like us. All of us all living creatures came from what we call the LUCA, though — the last universal common ancestor — which was a bacterium that lived about [four] billion years ago. So you really come from bacteria. The monkeys are our next door neighbours, so to speak, in their evolutionary history.

American astronomer and author Carl Sagan, seen here in a photo from the 1970s, wrote about the 'Great Demotions,' the concept that mankind's significance in the cosmos keeps getting downgraded with new scientific discoveries. (Hulton Archive/Getty Images)

This gets better and better now. Now we're the proud descendants of bacteria.

Exactly. However, and here comes my position, and I think that's something that I really try to make a point of telling people, is that what we see when we look at the universe is, indeed, it's very big. 

However, we are now looking at other planets going around other stars, and we are looking at the planets of our solar system, and one of the things that we have learned in the last 15, 20 years is that Earth is a very special planet indeed. It's not just another rock going around the star. It's a very privileged kind of rock, where the chemical composition and the properties of the planet as a whole — like the fact that we have a heavy moon, and only one moon stabilizes the tilt that the Earth has around its orbit — and that is what allows for the seasons and for a very small range of temperature fluctuations ... a range where life is possible. And that is extremely important. 

This awareness of us as a species ... this is the mindset that should be carrying us on in the 21st century.- Marcelo Gleiser

Then you add the history of evolution that you brought up, and you look at who we are, we humans. We humans are literally made of stardust. We are these atomic things made of stardust that are able to have self-awareness and understanding of questions related to our origins and to where we are in the universe and how precious our planet and life is.

And so, in a sense, that is bringing us back to the moral centre of the universe. Not the geographic centre of the universe, like pre-Copernican times, but to the moral centre, in the sense that we are the creatures that are able to think about who we are, and hence, we, in a sense, are the intellect of the universe as we know it. 

There may be other intelligences out there, who knows? But if they exist, they are very, very far away from us, so for all practical purposes, we're really alone here and in a very special planet. And that should fuel us with a sense of deep gratitude for existing in this place and also creating a moral imperative for our generation to do as much as we can to protect our environment and all kinds of life on this planet — and, of course, our fellow humans. Otherwise, we would be ruining the spectacular value of our planet with our greed.

It's mind blowing to hear this because I think I've always hewed to the existential dread, we-are-nothing side of the equation. And to hear you say, "Just think of the human being," and to think of this planet as the intellect of the universe, that's about as far as you can get from a cosmic demotion. 

Yay humans! That's what I'm trying to say, and it's important because people need to know this. They really need to know, especially nowadays with climate change, et cetera, and tribal divides. This is a moment where this awareness of us as a species — not as this tribe against that tribe, this political party against that political party — but us as a species in a very rare planet, this is the mindset that should be carrying us on in the 21st century. 

This interview has been edited for length and clarity.