“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” Arthur C. Clarke
Lee Billings is the author of Five Billion Years of Solitude and is speaking today at the IdeaFestival. He starts at the VERY beginning.
It's been 13.8 billion years. "Let me congratulate you on the improbable achievement of being here.... Most of the universe is empty space."
Spreading his arms wide, he suggests that if all of time were contained within his reach, human existence could be scraped away with a nail file. Moreover, cosmically speaking, we are perhaps nearer the end of complex life on earth than its beginning. And if we want to have a future after the next 500 million years, when planetary life will become untenable because of the changes in our sun, we might want to think of alternatives. We're capable, he says, of "choosing our own cosmic fate."
In the meantime, the search for life elsewhere "can give valuable context to life right here on this small cosmic speck of dust." Turning to the subject of his talk today, he points out that science and technological progress tell us that planetary formation is common.
In fact, planets are now "pouring out of the sky." He believes that 10,000 confirmed finds will soon be in the exoplanet catalog, which only came into existence in the past 20 or so years. Plotting those finds on a graph overhead, he points to "walls of worlds" discovered in just the past three or four years thanks to the space telescope Kepler. Interestingly, he says, Kepler has told us that OUR planetary system is atypical.
Billings walks the audience through two basic exoplanet detection techniques, the transiting and radial velocity methods. "Wobbles give you size. Transiting gives you mass." Kepler uses the transiting method.
The data so far, he is quick to add, doesn't support some of the wilder claims for habitable Earths that have reached the popular press. We're just in the formative stages of a new science. He explains that as late as the 1950's, many informed scientists believed that Venus might be a terrific place to live. It's emblematic, he says, of where exoplanetology is today.
Since direct observation of worlds tens of thousands of light years away is problematic because the competing light from the host star overwhelms the reflected light from nearby planets, we know what we know about the suitability of worlds for life based, in part, on how light interacts with chemicals as it passes through a planet's atmosphere on its way to our telescopes. Those signatures can be teased out in spectrographic prints to tell us what what molecules are present above the host body.
Thanks to that technique and the evidence offered by robotic explorers, we now know that Venus' crushing atmosphere is suffering from a runaway greenhouse effect. It would be a terrible place to live.
In the next few years, the enormous James Webb telescope will be able to peer at nearby stars to look for water vapor. And we could fund additional searches, but the trade-offs in a time of budget cuts are hard. One proposed exoplanetary telescope, for example, was killed in favor of funding two more Space Shuttle missions.
Meanwhile, "the planets are piling up." Asked during Q&A about what it would mean to find microbial life in our own planetary neighborhood, Billings believes it would be "disconcerting." If primitive life thives nearby, it means that, like planatary formation, it too is a common phenomenon.
And since we haven't heard from intelligent life elsewhere, is there a "filter" along this developmental path that prevents intelligent civilizations from flourishing?
The question lingers.