Dr. Fred Bortzbooks

Review of The Crowded Universe: The Search for Living Planets

by Alan Boss

(Basic Books, 240 pages, $26.00, February 2009)

Reviewed by Dr. Fred Bortz

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From Sputnik and Captain Video to Mars rovers and Battlestar Galactica, in fact and in fiction, humans (and other species) have been engaged in intra-planetary and interplanetary competition to rule the Cosmos.

For some participants, the prize is scientific knowledge. Others seek technological supremacy. A rare few are motivated by simple curiosity. Most seek fame, glory, or power.

People and nations are as avidly engaged in the Space Race today as they were a half-century ago, and for the same reasons. What seemed like a sprint to the Moon in the 1960s has now become a marathon. The United States has remained among the leaders, but it has faced dogged competition at every stage.

The latest quest, according to Alan Boss in The Crowded Universe: The Search for Living Planets, is the discovery of other solar systems with habitable Earth-like planets. A research scientist at the Carnegie Institution of Washington, Boss is both a renowned authority on the formation of stars and planets and a veteran of the political competition for research funds and resources.

"[W]e are on the verge of discovering how frequently Earth-like planets occur in our neighborhood of the Milky Way Galaxy," he writes in the Prologue. "In early 2009 [March 5 according to the present schedule], NASA will launch the Kepler Mission, the first space telescope designed specifically to detect and count the number of habitable worlds orbiting stars like our Sun."

Kepler will not be without competition. In late 2006, the European Space Agency launched CoRoT (Convection, Rotation, and Planetary Transits), a similar but smaller space telescope. Unlike Kepler, its mission is primarily to study the physical structure of stars by monitoring variations in their light. Most of those variations result from the rotation of the star's sunspots and mottled surface, and from changes in those spots and mottling caused by convection within the star.

The occasional transit of a planet in front of that star's disk as seen from Earth will also produce a characteristic short-term decrease in intensity. That dimming will repeat at regular intervals that match the planet's "year." It takes three such instances to confirm that a planet has been found.

The first detection might be a false positive caused by instrument problems or another phenomenon on the star. The second strengthens the transit hypothesis and determines the planet's orbital period. If the third dimming appears on schedule, the CoRoT team can add a new member to the current list of 330-and-growing extrasolar worlds.

So far, the CoRoT team has identified several extrasolar transiting planets, but none that both orbits in the star's "habitable zone" and is earthlike in size and composition.

With Kepler's launch date fast approaching, it may go online soon enough to win the race to find the first extrasolar Earth--especially if, as Bass predicts, such worlds are numerous.

"If this bold assertion is proved correct by Kepler and CoRoT," the Prologue concludes, "the implications will be staggering indeed: it will suggest that life on other worlds is not only inevitable but widespread. We will know that we cannot be alone in the universe."

In the main text that follows, Boss presents a journal-style history, with nine chapter divisions covering periods as short as four months or as long as six years.

The journal begins with an unsuccessful planet hunter about to throw in the towel on February 6, 1995. It ends three years from now when Boss expects NASA to hold a major press conference at which the leader of the Kepler mission "will have the honor of telling the world just how frequently Earths occur."

Following the journal is a brief and not particularly enlightening epilogue that provides the standard answers to Enrico Fermi's famous question: If the universe is so crowded, why haven't we heard from alien civilizations?

The chronological approach may not suit every reader's taste. Readers who prefer a strong narrative arc will find the inevitable side trips distracting. They will crave an organization that carries them, example by example, along the path that will lead to the future moment that an Earthlike planet is found in a nearby star's habitable zone with an atmosphere that suggests the presence of life.

But that weakness can also be a great strength. All the elements of the narrative thread are present, but the readers have to assemble it for themselves. They will appreciate Boss' approach if they love science and technology for open questions, possibilities, and problems rather than for answers and solutions.

The journal approach also allows readers to experience the nature of scientific life, with all the setbacks, blind alleys, and complex human relationships that make the process of discovery anything but linear.

Among the resulting insights are these: International cooperation is the norm, but unpublished information is carefully guarded when credit for an important discovery is at stake. Securing sufficient funds and managing projects or organizations require knowledge of how the political process plays out.

In Boss' account, the political players are generally honest, but they are also ambitious and savvy. It's a process he clearly loves carried out by people he genuinely respects.

When all is said and done, Boss would clearly prefer that his favorite theory of planet formation wins out over its competition. There are two reasons for this. First, it's more fun to be right than wrong. Secondly, if his theory is right, then habitable Earthlike planets are more likely to be commonplace. But as an honest scientist, right or wrong he will accept the verdict delivered by research.

Likewise, whether it is the Kepler or CoRoT team that provides the long-sought estimate of Earthlike worlds, he is eager for the results, declaring, "Either way, after centuries--if not millennia--of speculation and wondering, we will finally know just how crowded the universe really is."

Physicist and author Fred Bortz has explored planetary science in several books for young readers, including most recently Astrobiology.