"Civilizations in the universe" redux

In the January 2013 issue of Astronomy, I wrote a little piece about the likelihood of civilizations in the cosmos. That caused a big flow of letters from readers about their opinions, and I shared many of these several months ago. I got a straggler just a few days ago from reader Suzanne Searby, and I wanted to share it too. So here goes . . .


“The other day I happened to chance upon an old much-read copy of the January 2013 issue of Astronomy. It was fascinating reading. I was particularly interested in your ‘Snapshot’ on page 9 wherein you pondered the question of how prevalent life is in the universe. I have been trying to work out an answer to this problem myself in recent months, having been inspired by one too many cable ‘documentaries’ about alien visitations both current and ancient. I am astonished by the willingness of people to believe the most preposterous stories and speculations.

So I started thinking about the question of how many advanced civilizations there are apt to be in the Milky Way Galaxy, nevermind the rest of the cosmos. As a nonscientist but an avid consumer of Science Channel astronomy programs, I had begun to accumulate in my own mind a list of necessary conditions for life to have developed here on Earth. At some point, after having run through a rudimentary analysis of salient facts, I heard about the Drake Equation. And I was fascinated to learn that Dr. Drake’s factors were quite different from mine. And I concluded that this was a reflection of how much more we know now about our galaxy, the solar system, and star systems in general. In my ignorance, I was thrilled to find that someone besides me had tried to narrow it down. And yet it seemed to me that someone really ought to try to update the Drake Equation.

Then upon further reading, I discovered that someone actually had! The Rare Earth hypothesis comports nicely with what I had come up with in my crude way. I dare say this is not the last word on the subject. And in fact I did run across the ‘principle of mediocrity,’ the very name of which causes my fingernails to curl. But be that as it may, my own thought processes aided by a bit of rudimentary math on a scratch pad place me firmly in the Rare Earth camp. And this is assuming that most stars out there have one or more rocky planets in the habitability zone.

This is a subject that interests me greatly. My regret is that I have no one who actually knows what they are talking about to discuss it with.

Thanks for your very stimulating magazine.

Suzanne Searby.”