Sunday, February 18, 2007

Search for Intelligent Life

Where do we search for intelligent life? Forget mankind – because there isn’t any. But is it out there in the Milky Way? Or in the millions of other galaxies that dot this vast universe? Or is it deep inside the oceans – the realms of which we know far less than what we know about Pluto.

Statistically the probability that there is intelligent life out there in space is pretty high. Milky Way itself has about 300 billion stars and it is just one of the 100 billion other galaxies that we know about. So that’s a lot of stars out there (and human beings can only see about 5000 of them from naked eye!). In the 1960s, a professor at Cornell named Frank Drake worked out a famous equation designed to calculate the chances of advanced life in the vast universe based on a series of reducing probabilities.

Under Drake’s equation you divide the number of stars in the universe by the number of stars that are likely to have planetary systems; divide that by the number of planetary systems that could theoretically support life; divide that by the number on which life, having arisen, advances to a state of intelligence; and so on. At each such division, the number shrinks colossally—yet even with the most conservative inputs the number of advanced civilizations just in the Milky Way always works out to be somewhere in the millions.

Interesting eh? Now let’s look at Earth itself. This plant has been in existence for circa 4.5 billion years. And if you want to look at history of the earth compressed into a 24 day, this is what you get:

Life begins very early, about 4A.M., with the rise of the first simple, single-celled organisms, but then advances no further for the next sixteen hours. Right until almost 8:30 in the evening, with the day five-sixths over, Earth has only single celled microbes to show to the universe. Then, finally, the first sea plants appear, followed twenty minutes later by the first jellyfish and some simple moss. Just before 10P.M. plants begin to sprout up on the land. Soon after, with less than two hours left in the day, the first land creatures follow.

Thanks to ten minutes or so of balmy weather, by 10:24 the Earth is covered in the great carboniferous forests whose residues give us all our coal, and the first winged insects are evident. Dinosaurs come onto the scene just before 11P.M. and rule the world for about three-quarters of an hour. At twenty-one minutes to midnight they vanish and the age of mammals begins. Humans emerge one minute and seventeen seconds before midnight. The whole of our recorded history, on this scale, would be no more than a few seconds, a single human lifetime barely an instant. Throughout this greatly speeded-up day continents slide about and bang together at a pace that seems reckless. Mountains rise and melt away, ocean basins come and go, vast glaciers advance and withdraw. And throughout the whole, about three times every minute, somewhere on the planet there is a spark of light marking the impact of a mansion-sized meteor or one even larger. It’s a wonder that anything at all can survive in such a pummeled and unsettled environment. In fact, not many things do for long.

Perhaps an even more effective way of grasping our extreme recentness as a part of this 4.5-billion-year-old picture is to stretch your arms to their fullest extent and imagine that width as the entire history of the Earth. On this scale the distance from the fingertips of one hand to the wrist of the other is the period of single cell life. All of complex life is in one hand, and in a single stroke with a medium-grained nail file you could eradicate human history.

We humans – and humanity as a race – are insignificant in the history of this planet. And so I return to search for intelligent life. Considering humans have been on this planet for such a short period of time, were there intelligent species prior to us? You would naturally assume that if they had been there – then there would be some traces of it left; some archaeological evidence; some cities; some fossils; something!!! But think about it – if human race were to be wiped out today because some Bangalore sized asteroid fell through the skies, and if all 5 billion odd people were to perish, only about 50 or so dead bodies would ever end up as fossils! And devastated cities don’t leave any traces of existence if you leave them untouched for millions of years. Heck we can’t even find Atlantis which is supposed to have existed 10,000 years ago.

With such short odds of having any traces left behind, and in our 24 hour time scale of Earth’s history, there is a meteor related mass extension every 3 minutes (or 10 million years), there is a huge probability that there were intelligent species before mankind. Unfortunately we may never know about them because our eyes are directed at the skies.
* I have relied heavily on the book "Brief Hisotry of Nearly Everything" by Bill Bryson for the language behind the statistics.
Clicky Web Analytics