"Alien life, coming slowly into view"

Courtesy: New York Times, 29 March 2011

Astronomy and astrophysics professor, Ray Jayawardhana says he remembers "the first time the concept of another world entered my mind."....
I also remember the first time I heard of "The Drake Equation".  And I've thought of it often since.  Without going to Google to check it out, this is what I remember of it: that it's an equation worked out by an astronomer professor, Frank Drake, for a symposium in the US on extra terrestrial life, perhaps sometime in the seventies.  It goes something like this: the number of extra terrestrial intelligent Lifes out there (let's call that "N") is equal to....

• The number of stars in the universe ("S"); times....
• The proportion of those that are like the sun; times....
• The proportion of those that have planetary systems (P); times...
• The proportion of those that have planets like the earth (E), rocky and watery; times...
• The proportion of those that are in the zone that allows life as we know it (now known as the "goldilocks zone", not too hot, not too cold); times...
• The proportion of those that have actually given rise to life; times....
• The proportion of those that have intelligent life; times....
• The proportion of those that have intelligent life that has been around long enough to give rise to a society that sends out radio signals.

And there you have it!  That's "N". [As I say, the actual Drake equation may not be exactly like this, as I'm working from memory; the key is that that's the principle and if you want to get the actual Drake equation, it's easy enough to google]

Each of the proportions above, after S may be very small, but given the initial large number of S, the eventual number of N may be very large indeed. S is something like 200 billion stars per galaxy times about 200 billion galaxies, which if I remember my simple maths comes to 4 times 10 to the 22nd, ie 4 with 22 zeros; and I saw an article recently that suggested we may have underestimated those numbers by a factor of up to TEN!)

Now we have the Kepler satellite out there finding more and more "P", many more than we thought, and the number "E" seems to be rising too.

I've been thinking that we may find life on another planet in my lifetime, and here's Jayawardhana saying exactly the same in his article!  What an exciting time to live -- even if we are assailed on all sides by Arabian uprisings, and the upwelling of the earth itself. Perhaps finding other life will give us some perspective...

Article: here.  PDF: here.