"Science—knowledge—only adds to the excitement, the mystery, and the awe of a flower. It only adds. I don't understand how it subtracts."
That's one of the first comments the late, great physicist Richard Feynman makes in a wide-ranging interview from the 1981 television documentary, The Pleasure of Finding Things Out. I recommend you watch it, if you have the time. The title comes from Feynman's description of the visceral thrill that accompanies discovery, a thrill that intensifies in direct proportion with the discovery's profundity and certitude.
I was reminded of Feynman's documentary and quote one day in 2009, during a hike on a telescope-studded Chilean mountaintop with the astronomer Debra Fischer. Fischer is a planet-hunter, one of a handful of individuals around the globe who have discovered dozens of alien worlds, and who are bent on finding more planets like our own. She was using a telescope there to search for terrestrial planets around Alpha Centauri, the nearest neighboring stellar system to our own Sun.
It was a clear, sunny afternoon, with only a single condor spiraling in the sky—a good omen for telescope work, since more soaring condors would have meant hot, rising air, atmospheric disturbance, and muddy views of the night sky through the telescope. We also found an apricot tree, improbably laden with fruit in the midst of what was essentially high desert. Barely touched, the ripe apricots fell into our open hands, and as we paused and ate, we speculated on how the tree had come to be there, and how it had managed to grow and bloom and bear fruit. (The explanation turned out to involve a beneficent groundskeeper who had planted the tree and hooked up an irrigation line, but bear with me.)
You can, of course, trace such a question back to the rarefied abstraction of why there's anything at all rather than nothing whatsoever, but I prefer the more concrete consideration that, without a rocky, warm, wet planet to support a complex biosphere, neither Fischer's apricot nor Feynman's flower could have existed in the first place, let alone be savored and appreciated.
Science is filled with big questions, and astronomy and its subfields are blessed with some of the biggest. For example, where did the universe come from? How is it that its expansion is accelerating? Why is it that time only moves in one direction? These are great, worthy mysteries … but no matter how many billions of dollars we throw at them, I'm not at all convinced that we'll be definitively answering any of them anytime soon—or that we even know how to properly address them yet.
Looking for other habitable or inhabited planets is different, partially because we already have such a well-characterized template to guide us: Earth, and its defining, life-enabling properties.
Many of our planet's most salient features—its liquid-water ocean, its atmospheric composition, and its global population of living things—appear relatively straightforward to remotely detect across the vast distances of interstellar space. That's largely why I believe that, quite possibly for the remainder of my lifetime, the most profound question that can be answered with reasonable certainty—the most pleasurable thing that can be imminently found out—is the frequency of living worlds around other stars.
I'm admittedly biased (just look at my Twitter feed—it's clear what my interests are), but my argument rests on facts: The research architectures and observational capabilities required to find Earth-like planets in our region of the galaxy, and determine whether or not some of them harbor life, are already reasonably well-defined. Public interest in (if not knowledge of) the search for alien life is high, and nearly universal. And, in comparison to tasks like finding the Higgs boson, establishing the precise nature of dark energy, or experimentally validating string theory, completing much (though not all!) of this "planetary census" simply isn't that expensive.
Imagine if we eventually discover tens, even hundreds of potentially habitable planets within a few hundred light-years of our solar system. Or, instead, imagine that we somehow find no worlds remotely suitable for life as we know it. Either result, and all those in between, would constitute a shocking revelation.
What if we are cosmically alone, on a planet as anomalously unlikely and fertile as a fruit tree flourishing in an arid wasteland, or a flower blooming in a desert? What if worlds like ours are common as grains of sand? Does the universe hum and throb with life, or does eternal silence and sterility reign outside of our small planet? The truth is, no one really knows. But that will soon change. And when it does, this knowledge can only fill our lives, our world, and our future with more excitement, mystery, and awe.
This week, NASA is releasing a new batch of discoveries from its premier planet-seeking spacecraft, Kepler. The editors at BoingBoing have kindly invited me to come aboard to blog about these discoveries, and other insights from exoplanetary research. My goal is to take you on a journey through the past, present, and future of the search for habitable exoplanets, so that you can better understand—and, potentially, even get involved in—this exhilarating scientific frontier.