== Essential Questions About Alien Life ==

And now the news from Alpha Centauri . . . (oh, I’ve waited for so long to utter those words! News. From Alpha Centauri) . . .

After an incredible decade, in which the number of planets known beyond our solar system increased from zero to several thousand, astronomers have detected an Earth-sized world orbiting between the two stars nearest to our system, Alpha Centauri A and Alpha Centauri B. Much too hot to sustain life, it nevertheless will help in narrowing down the search space for others. Moreover, now we have a target for the first interstellar probes, which are already under discussion. Indeed, the youngest of you readers may live to see the launch.

Ah, but this raises the perennial question. If planets are more common than we ever thought, then what about life-worlds? And even alien intelligences?

I have been involved in this topic all my life, having grown up in Southern California, the part of human civilization least rooted in the familiar, traditional or . . . perhaps . . . sane. I am best-known today as an author of novels and stories about our many possible-plausible futures, including some that explore a wide range of possible extraterrestrial civilizations. My scientific career, ranging from optics to astrophysics, led to papers about SETI in the 1980s that include what is still the only full review article in the field, compiling all then public theories for what I called The Great Silence, but that is now more widely known as the Fermi Paradox.

(See a collection of articles and speculations about the Search for Extraterrestrial Intelligence (SETI))

The Fermi Paradox refers to a question posed by the great physicist Enrico Fermi in the 1940s, demanding: “If it seems so likely the universe may host other life forms, how come we haven’t seen any signs?”  Not just of radio beacons, but of mighty structures that our own descendants might someday build out there in space. Or leakage from chatty commerce between civilizations. Or indeed, any trace that the Earth was visited during the 2 billion years that it was “prime real estate” with an oxygen atmosphere, but nothing higher than slime molds to defend it. (more…)