Physics, Earth & Space Icon Physics, Earth & Space

Denton Turns Sagan’s “Humdrum Star” on Its Head

Michael Denton

On a new ID the Future episode, biologist Michael Denton talks with host Sarah Chaffee about the remarkable fitness of a range of properties seen in water and in light. Download the podcast or listen to it here. It’s particularly satisfying to hear Denton turn a frequently heard dismissal of our Sun on its head.

How Silly the Old People Were

Carl Sagan in Cosmos gave the idea perhaps its most iconic expression. In Episode 7, he lectures to a classroom of Brooklyn schoolchildren about how it was once thought that Earth occupied an “important” place in the cosmos. Tut-tut, how silly the old people were, before we realized that our solar system is not at the center of things but way out on the edge of the galaxy, thereby guaranteeing (this leap doesn’t quite follow) our cosmic insignificance. He goes on to ponder:

For as long as there have been humans we have searched for our place in the cosmos. Where are we? Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people.

Yet the fact that the Sun is “humdrum” or “ordinary” may be the most extraordinary thing about it. Dr. Denton discusses the fortunate circumstances characterizing visual light, needed for vision and photosynthesis. He concludes:

The big deal is that being an ordinary star means that the vast majority of stars in the cosmos put out their energy in the visual and infrared area, bands of the electromagnetic spectrum. So being “ordinary,” what this means is that the universe — it’s somewhat ironic and it seems a bit counterintuitive — it means the universe is profoundly fit for biological systems like ourselves. The Sun is an ordinary star, and that’s a very big deal. The universe, as I describe it Children of Light, is flooded with the light of life.

A Double Dilemma

“Flooded with the light of life”: What a beautiful way of putting it. You could add that it creates a double dilemma for materialists. The universe is “flooded with the light of life,” in Denton’s apt phrase. Yet so far as we know, life on Earth is a singularity. This is certainly counter to Carl Sagan’s expectations. Yet it’s possible that Sagan, and Stephen Hawking and others, may prove right about the cosmos being home to many forms of extraterrestrial life, including intelligent forms. Only time can tell. If Sagan was correct, then Denton’s “ironic” observation about light’s insanely special fitness for life, life like ours, really comes to the fore.

Light was finely tuned for life, whether in a multitude of homes in the cosmos or in just one. Either way, we’re prompted to ask the same question: Finely tuned by whom? And why?

Denton’s new book is Children of the Light: The Astonishing Properties of Sunlight that Make Us Possible. It is the latest entry in the Privileged Species series.

Image: Carl Sagan lectures to school kids, in a scene from Cosmos (screen shot).