A SETI Day Q and A
From John, 14 September
Books on cosmology and
astrophysics are my favorites, too. (See yesterday's blog for one of
the more imaginative ones!)
itself is an entirely satisfactory way of determining the probability of
ET life. However, I don't believe there is a "Drake Equation
conclusion" since the numbers that it requires range from the fairly
definite to the purely fanciful. You can make it come out however
you like by varying your assumptions.
(Not to ruin the suspense for A, B, C, and D, but "yes.")
sounds like John is arguing that all the above conditions are necessary,
including, perhaps, even a dinosaur phase, before humans can emerge.
At least one obvious counter is that if the dinosaurs had not been rendered
extinct, perhaps they would have developed intelligence.
But beyond that, nobody really knows how many of these special
conditions are necessary or even desirable for life to develop.
A "narrow zone" in a galaxy
is a pretty big place nonetheless. For example, all the
refrigerators and freezers (including walk-in!) built on earth since the beginning of human
life wouldn't be large enough to encompass even the tiniest fraction of
a galactic "habitable zone." And, of course, we're not all that
sure that a habitable zone is, or a (hypothesized) uninhabitable zone
D). The age of our universe being only 13.7 Billions of years. Would not the Drake Equation be more suitable if the age of our universe were several hundred billion years of age greater? With the Milky Way being only 10 Billion years of age and our solar system and Earth less than 5 Billions years of age has sufficient time yet passed within our universe for there to be many propitious regions?
It takes a
certain mind set, one I don't possess, to put the word "only" before
"billion," at least when referring to time as measured in years.
In hundreds of billions of years, in fact, the universe will be a
much duller and more boring place, with lots of cinders instead of stars
to keep the current variant of "us" company, or so our
astronomical understanding predicts. Put another way, it has
taken us only a few hundred years to go from not knowing what or
where the stars are to seriously contemplate visiting them. Given
that stars and their planets have been forming and continue to form
throughout those billions of years, the most likely scenario is that
very few civilizations are close to our level of development, and the
vast majority are either way behind or enormously ahead of us.
Not withstanding my gentle flippancy and pooh-poohing of some of the arguments above, it's at least possible that John is correct. The best argument for being alone in my opinion is the simplest: If we're not, where is everybody? This is known as the Fermi Paradox, and books have been written on the subject. Even I weighed in with my discussion of Nirbs. We simply don't know enough to answer the question conclusively, or even tentatively.
As a matter of personal belief, which, along with 50 cents plus shipping will get you a fine UPS on eBay, I think it's unlikely in the extreme that we're it. Yet it doesn't matter what I believe or what John appears to believe. In the general scheme of things, the SETI program—ours and those of other organizations and scientists—costs society much less than the unpaid taxes of people who spend their time writing blogs instead of toiling productively. (Which subject will be covered shortly; it's not easy to escape my ruminations.) So, space aliens or none, the question of whether we should be searching for them is trivially easy to answer: It costs almost nothing, and the reward for success is potentially spectacular. If entrepreneurship were possible in astronomy you couldn't ask for a better business plan.