I’m writing this post for two reasons: to recommend a new book by Columbia astrobiologist Caleb Scharf, and to defend an old book of mine.
Scharf’s book is The Copernicus Complex: Our Cosmic Significance in a Universe of Planets and Probabilities. I liked it so much that I brought him to Stevens last month to talk about it. Here’s how I introduced him:
“The Copernicus Complex addresses some of the deepest questions humans have ever asked. How weird are we? Was our existence highly probable, or improbable? Even miraculous? You can break this question down into more specific questions: How probable was our universe? Our galaxy? Solar system? Planet? How probable was life? And how probable were creatures like us, who can ponder their probability? For thousands of years, anyone could speculate about our weirdness, from Plato to pot-smoking college kids, because no one had any answers. It was just philosophy, pure guesswork. But new scientific discoveries are informing and guiding estimates of our probability. This is the story that Caleb Scharf tells brilliantly in The Copernicus Complex.”
“Pure guesswork” was a gratuitous jab at my Stevens philosophy buddies. Otherwise, my introduction was sincere, especially the last sentence. Scharf provides an exceptionally clear, entertaining, up-to-date report on observations and speculations bearing on our weirdness, or lack thereof.
Scharf delves into exoplanets (4,000 discovered so far), and also microbiomes, Bayesian inference, planetary dynamics, multiverses, the anthropic principle, the Fermi Paradox, and lots of other fascinating topics. All this work is provoking reconsideration of the Copernicus Principle, which holds, as Scharf puts it, that “we are not the center of all existence; we are not ‘special.'”
Now I come to the second reason for writing this post. In The Guardian, journalist Tim Radford praises Copernicus Complex as “an intoxicating collection of questions answered with other questions. A couple of decades ago, physicists spoke confidently of a theory of everything, and one or two even proposed an end to science. All has now changed. The mysteries have multiplied.”
I don’t know of any physicists who proposed “an end to science” two decades ago, but I did. In my 1996 book The End of Science, I argued that “pure” science, which I defined as the “quest to understand the universe and our place in it,” might be drawing to a close. “Further research may yield no more revelations or revolutions but only diminishing returns.”
I addressed the same questions that Scharf does in Copernicus Complex, but I concluded that questions about our probability might never be fully resolved. “You cannot determine the probability of the universe or of life on Earth,” I wrote, “when you have only one universe and one history of life to contemplate. Statistics require more than one data point.”
I did not anticipate the thrilling recent surge in discoveries of exoplanets, which have revealed that planetary systems are common. But answers to the biggest questions remain as elusive as ever. Scientists still don’t know why our universe takes the form we observe, or how life began on Earth more than 3 billion years ago, or whether life exists elsewhere.
I hope this situation changes, but I fear it won’t, in spite of continued research in cosmology, astrobiology, and other fields. During his talk at Stevens, Scharf acknowledged that we might never observe exoplanets in sufficient detail to know, with certainty, that they harbor life.
“So are we unusual or not?” he asks toward the end of his book. “Neither side is yet a winner. But we are much, much closer to an answer than we have ever been in the history of the human species; we are on the cusp of knowing.”
We may be on the cusp of knowing and yet still infinitely far away.
John Horgan directs the Center for Science Writings, which is part of the College of Arts & Letters. This column is adapted from one originally published on his ScientificAmerican.com blog, “Cross-check.”
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