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Review: The Copernicus Complex

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The Copernicus Complex: Our Cosmic Significance in a Universe of Planets and Probabilities
by Caleb Scharf
Scientific American / Farrar, Straus and Giroux, 2014
hardcover, 288 pp., illus.
ISBN 978-0-374-12921-7

Is life—particularly intelligent life—commonplace or rare in the universe? In recent years there appears to be arguments for both. On the one hand, astronomers have discovered thousands of exoplanets, setting aside concerns that solar systems might be rare. On the other, though, most of these exoplanets are oddballs compared to the planets in our own neighborhood, suggesting that our particular solar system might be rare. Similarly, the discovery of extremophiles in regions of our planet long thought inhospitable to life suggests that life could find homes on other worlds. Yet, searches for any such intelligent life have come up empty.

“Having correctly displaced the Earth from the center of things, most astronomers took this averageness as a new gospel,” he writes.

That conundrum is at the heart of The Copernicus Complex, by astrobiologist and science writer Caleb Scharf. In the book, he takes on two competing beliefs: the “Copernican principle” that, for centuries, has argued that the Earth has no special place in the Universe; and the “anthropic principle” that argues that the universe is fine-tuned to support life. Scharf, in the book, argues for a compromise position between the two.

Scharf devotes much of the book to tearing down the Copernican principle. For centuries, he notes, astronomers have worked to argue that the Earth isn’t particularly special: neither it, nor the Sun, nor the Milky Way galaxy, are the center of the universe. “Having correctly displaced the Earth from the center of things, most astronomers took this averageness as a new gospel,” he writes.

For example, he argues that solar systems like the Earth are not common, based on what’s been discovered in the last two decades. Many have “hot Jupiters” orbiting close to their stars, or worlds in eccentric orbits, that would appear to rule out the presence of Earth-like worlds. He also devotes some discussion to the challenges in understanding just how our own solar system formed.

However, Scharf is not willing to join proponents of the anthropic principle, or otherwise conclude that life, intelligent or otherwise, is rare. He instead offers an alternative, which he calls the “cosmo-chaotic principle”: life, in that concept, “will always inhabit the border or interface between zones defined by such characteristics as energy, location, scale, time, order and disorder.” It’s not as elegant as the Copernican or anthropic principles, but does suggest that the conditions for forming life are complex, but not necessarily unique.

“So are we unusual or not?” Scharf asks near the end of The Copernicus Complex, an enlightening read even for those people familiar with many of the astronomical and astrobiological topics discussed within. He is smart enough to acknowledge that we don’t know, rather than hazard a guess one way or the other. “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.”