An article in Time Magazine’s latest issue caught my eye as I thumbed through it while waiting in line at the grocery store. The magazine is running a feature called ‘10 Ideas That Will Change the World,’ and they tend toward being optimistic takes on huge problems. Thus the deficit gets an essay about how we’re going to fix it, while Afghanistan gets a thumbs-up for progress in the right direction. The article finds gold in everything from direct mailings (OK because they help charities raise money) to modern airports, which are creating a new kind of community.
And in the midst of this is a puzzling piece by Jeffrey Kluger called ‘Relax: You Don’t Need to Worry About Meeting E.T.’, where the upshot is: ‘Don’t worry about contact with extraterrestrial civilizations. It will never happen.’ Here’s a quote:
Humans and aliens haven’t connected yet, but with 1022 stars out there (that’s 1 with 22 zeros), it’s just a matter of time — right? Wrong. If exobiologists have learned anything, it’s that you and your kids and their kids’ kids will probably never hear the slightest peep from an alien. If E.T. the movie star is your idea of what extraterrestrial life might be like, you will be disappointed. If your thoughts run more to War of the Worlds, you can breathe easy.
Breathe easy? Let’s assume for a moment that Kluger is right, that contact with an extraterrestrial civilization is simply not going to happen at any time soon or in the future. If we knew that to be the case, would it be a cause for relief? For optimism? Maybe I travel with the wrong crowd, but most of us would be disappointed at the thought that we might never know whether intelligent civilizations exist around other star systems. Even those of us who think a confirmed SETI signal is unlikely any time soon — and I am one of these, believing that intelligent life is extraordinarily rare — would still hope to be proven wrong, and thrilled if we were.
Failure Is Not an Option
Kluger mentions both ‘E.T.’ and ‘War of the Worlds,’ so he’s not just reacting to disaster-oriented invasion films like ‘Battle: Los Angeles.’ The magazine seems to be implying that just the knowledge that we are either alone or unable to communicate with other civilizations is the solution to what Time bills as one of our worst problems. That phrase is used in the lead-in to these ten essays: ‘Our best shots for tackling our worst problems…’, of which knowledge of an alien culture is billed as number three on the list. And I’m wondering, since when is the idea of failing in our attempts to gain scientific knowledge considered the solution to a problem?
The essay goes through the difficulty in finding ETI, including our reliance on a sample of one to construct theories about life’s development on a planet, our uncertainty about how likely life is to develop even on worlds similar to our own, and the difficulty in finding an alien culture through SETI. That last point gets a quote from Don Brownlee (University of Washington), who notes the distances involved in going from star to star in the galaxy and says, “If the nearest hundred or thousand stars don’t have life, we probably won’t ever, ever, ever know about it anywhere else.”
That’s an interesting point if you strip it down to its basic assumptions. Picking up signals from a civilization something like our own would be a hugely difficult proposition even if they were being broadcast from a place as nearby as Centauri B. Pushing the distance out to a thousand light years makes things even more problematic. But we don’t know how long civilizations can exist, and the possibility of one living long enough to be thousands of years — if not millions — more sophisticated than our own can’t be ruled out. The factors that make a chance reception of a signal from a civilization like ours so tricky would be negligible to such an advanced species.
That possibility is one reason why we continue to look. And the fact that we have a sample of just one living planet to base our conclusions about life on is why we continue to look for life elsewhere, to broaden the sample and learn more about life’s mechanisms. So I don’t find any of this convincing in terms of making our detecting an alien civilization less likely to occur.
SETI, Distance and the Odds
But the point about stellar distances is still an interesting one. For one thing, we have a new paper by Joseph Catanzarite and Michael Shao (JPL) analyzing the Kepler science results that attempts to extract an estimate on how common Earth-like planets are. Let me quote from its summary:
Kepler’s science team has determined sizes, surface temperatures, orbit sizes and periods for over a thousand new planet candidates. Here, we show that 1.4% to 2.7% of stars like the Sun are expected to have Earth analog planets, based on the Kepler data release of Feb 2011. The estimate will improve when it is based on the full 3.5 to 6 year Kepler data set. Accurate knowledge of nEarth is necessary to plan future missions that will image and take spectra of Earthlike planets. Our result that Earths are relatively scarce means that a substantial effort will be needed to identify suitable target stars prior to these future missions.
We’re dealing with results that will be improved as the Kepler mission continues, but the figures so far cited indicate that planets like ours aren’t terribly common. Yes, it’s true that even with these low percentages, the option is still open for millions of Earth-like planets throughout the galaxy, given the sheer number of stars involved. But that other big imponderable — the question of how long civilizations last — still faces us. If they don’t tend to survive very long after they develop the ability to destroy themselves through technology, then Brownlee’s point has more resonance. And certainly these numbers say the nearest Earth-like planet may be a substantial distance away, a fact that will make studying it even more challenging than we first thought.
So yes, looking for ETI is difficult. But I can hardly share Kluger’s certainty in Time. He ends the essay, having looked at the possibility of alien extremophiles on Earth, by saying this:
Of course, even such aliens would hardly be the kind we either crave or fear — those who could regale us with tales of what things look like on the other side of the cosmos on the one hand, or conquer us with their superior intellects on the other. Too bad — or maybe very good — you’re never going to see them.
‘Never’ is a curious word to use in the midst of a great scientific investigation, one in which we hope to start assigning some reasonable values to the Drake Equation and find out just where we stand in terms of our place in the galaxy. We know so little, and Kepler and CoRoT are only the beginning of our space-based exploration of exoplanets increasingly like our own. We all have our views on this, and some of us are going to be proven wrong, but our investigations into extraterrestrial life are among the most energizing scientific projects in the history of our species. How could anyone possibly regard a failure to learn the answer as a good thing?
The paper cited above is Catanzarite and Shao, “The Occurrence Rate of Earth Analog Planets Orbiting Sunlike Stars” (preprint).