Continuing to explore yesterday's theme of Life On Other Worlds, today, I thought I'd start with the most recent discovery from the extrasolar-planet crowd; two worlds, both (from our vantage point) in the constellation Cygnus, that orbit double stars. (See the full article here.) If you were a resident of one of these planets (which seems unlikely, for reasons I'll discuss in a moment), you would see two suns in the sky.
Luke! Use the Force, Luke!
It was long surmised that double (and triple) star systems would not have planets in stable orbits -- that a gravitational field generated by two heavy objects would have an odd enough shape that it would make it impossible for a planet to settle into a regular path around them. The new study, however, surmises that such combos are "common" in the universe, however incomplete our understanding of the classical mechanics of the situation.
However, neither of these worlds is a good candidate for being Tatooine -- both of the planets, named Kepler 34b and Kepler 35b, are large, gaseous worlds, more like Saturn than like Earth. Additionally, astronomers suspect that both of these planets, and probably most planets that orbit double stars, would have wildly changing climates due to the varying proximity of the planet to each of its stars at different times during its year.
Be that as it may, I'm blown away by how many planets these folks have discovered, since the first evidence of an extrasolar planet several years ago. The current total stands at 728, and every week more are found. This further bolsters the conjecture I've had all along -- that planets, and very likely life, are common in the universe.
The exciting part of all of this planet-finding is finding out how similar the rest of the universe is to our own cozy little solar system. The more we look out there, and the better our instruments get, the more planetary systems we find. The Drake equation, named after astronomer Frank Drake, is a way of estimating the number of planets with intelligent life, by boiling the entire argument down to a few parameters, estimating the probability of each, and then multiplying the probabilities. One of the parameters - f(p) - is the fraction of stars which have planetary systems. Back in the 70s, when I was in college, f(p) was thought to be quite low. The general consensus was that the formation of our own planetary system was something of a fluke, and that the likelihood of there being such systems around other stars was small. However, as astronomy, and its associated technology, has improved, we are now finding that many - perhaps most - stars have planetary systems. Estimates of f(p) start at around a very conservative 20% and, according to some scientists, might range as high as 50 or 60%.
Still, "planets" does not equal "life," and "life" does not equal "intelligent life." We currently have no way to figure out if there is intelligent life out there - the distances are so amazingly huge that any contact is prohibitive. Even if Kepler 34b and 35b were hospitable places, which they're not, they're 4,900 and 5,400 light years away, respectively. If we sent a focused radio signal saying "hello" to the Luke Skywalker, we'd have to wait a minimum of a little under ten thousand years to receive a message saying, "Help me, I'm caught in a trash compactor!" in response, which might be a little too late to do anything helpful. The closest star to ourselves, other than our own sun, is Proxima Centauri, which is 4.3 light years away. There, the lag time, assuming an immediate response, would still be 8.6 years.
And that's for radio signals, traveling at the speed of light, which is three hundred million meters per second. Our fastest man-made vehicle, the Voyager space probe, is moving at about fifteen thousand meters per second - twenty thousand times slower than the speed of light. At that speed, and not counting relativistic effects, it would take Voyager 86,000 years to get to Proxima Centauri, if it were heading that direction, which it's not.
All of this makes any kind of contact by whatever intelligent life is out there very unlikely indeed, regardless how common I might suspect it is. Now, I strongly believe that the combined forces of abiotic production of organic chemicals, coupled with evolution by natural selection, make it virtually inevitable that intelligent life has arisen many times in the history of the universe. On the other hand, however thrilling the scene in Contact was, in which Elly Arroway finds the transmission from an alien culture, however exciting the final moments of Star Trek: First Contact were, when the Vulcan walks out of the spacecraft and the people of Earth finally find out that they are not alone, I think that such an occurrence is monumentally unlikely. The distances are much too big, and Einstein's general theory of relativity, along with its requirement of the speed of light as a permanent speed limit, seems to be strictly enforced everywhere except possibly Switzerland. But even if they're not likely to contact us, I'm still virtually certain that we're not alone in the universe. As a biologist, I find this incredibly exciting, and it is a shame that projects like SETI have such a low likelihood of succeeding.
Astronomers are pioneering novel ways of finding extraterrestrial life, including developing methods for detecting biotically produced compounds in the atmospheres of extrasolar planets. These techniques are in their infancy, but at least give hope that we might be able to answer the question of the existence of extraterrestrial life without having to receive a radio transmission or an actual visit.
You have to wonder how the discovery of incontrovertable proof of the existence of intelligent life elsewhere in the universe would change our worldview. It certainly would knock askew our sense of being at the center, left over from the Judeo-Christian idea of humans as God's Favorite Species. It would confirm what biologists have claimed for years, that the abiotic genesis of life and organic evolution are common and universal. And, most importantly, it would give me a much-needed excuse to brush up on my Klingon.