Are we alone in the universe?
The one question that fascinates me more than any other. And my perspectives are these.
The sheer complexity of biological forms makes me think that the evolution of intelligent life forms (such as humans) is likely to be a rather sparse occurrence. There will be many Earth-like planets … perhaps at least millions in the outer arms of the Milky Way revolving around stars like the Sun that the Earth revolves around. But the temperatures have to be just right for water to be plentiful in all three states. What were the stuff available in the early Earth that created the conditions that led to the emergence of primitive life forms? A planet with a lot of volcanic activity, lot of carbon-based complex organic molecules, a planet with continental plates slowly drifting, pushing, merging, separating, rising, and falling, lots of lightning, etc. How many planets will have all these enablers? Reduces the candidate planets to perhaps thousands.
Then on planet Earth, unicellular life evolved to more complex life forms only after billions of years of some sort of a hiatus … who knows why that hiatus happened and why suddenly there was a sudden explosion … the Cambrian Explosion. Is there a guarantee that life once started will inexorably flourish? Life could stutter and sputter for billions of years without reaching the next stage … or indeed, it could wither and die. So, how many planets in the Milky Way galaxy would see life exploding in all its diversity as it did here on Earth?
Even when life explodes in all its richness, it can lead to reptiles or birds or fish … would dinosaurs have ever evolved to some higher states of intelligence? Could dinosaurs have ever created a technological civilization like us humans? Some fortuitous event on planet Earth led to the extinction of the dinosaurs which enabled tiny mammals to get out from their hiding places and start to roam the wide open spaces.
Lastly, is there any inevitability that mammalian evolution will lead to intelligent creatures? Can’t mammals just end up being cows and horses and monkeys and zebras … a planet Earth with all the creatures … just without the humans.
All these fortuitous circumstances dramatically and drastically reduce the likelihood that there are intelligent beings elsewhere in the Milky Way. Of course, Milky Way is only our home galaxy and the visible universe is teeming with billions of them. So, even if there were to be just us in our galaxy, that would imply billions of planets in the universe teeming with life … an awesome prospect indeed.
That raises the next question — why have not we been visited by extraterrestrials then? Perhaps because of the distances. What about finding E.T. using radio telescopes? That endeavor of course goes on … started half a century ago which is less than the blink of an eye in cosmic scales. I hope something comes out of that endeavor … and what a time it will be when finally we do get definitive evidence of life elsewhere. What sort of life will it be? How much more advanced than us? What will we learn? What will they have to teach us? Should we be ‘careful’ lest these creatures bear ‘evil’ intensions and try to destroy humanity? Bewildering and intriguing questions all …
When is this mystery going to get resolved? I hope to live to find an answer but somehow I think the chances are low. Perhaps we need to focus our efforts on galaxies where there is greater probability of the presence of life — galaxies which should be teeming with second and third generation stars and therefore lots of carbon and oxygen and other building blocks of life. Is our Milky Way such a galaxy? What about Andromeda, our neighbor? What about the Local Group? And yet, what will happen even if we detect life after all … I think we’ll still need to go through the phases that we have to go through … whatever phase humanity is in right now … adolescence, childhood, whatever … humanity will have to grow up at its pace and make the mistakes that it has to.
So that raises the question: is humanity fundamentally capable of being a space-faring civilization? Are there fundamental limits to how far humans can grow? Is our intellect and intelligence capable of designing in time the spaceships that will fly close to the speed of life and ferry us to other stars and other galaxies which will require even more ingenious ways of space travel. When is it going to happen — when will humans colonize ten habitable planets in the galaxy? And is it inevitable?
This is a strange time to be alive indeed. I remember Carl Sagan saying that his time was the greatest time to be alive. Yet he wished to see certain things happen in his life and perhaps those things did not happen. I for one am very confused about this — whether to be glad that I live in a time of radio telescopes and Hubble and Chandra or be sad that I am not living a thousand years from now when many more of nature’s mysteries would have been resolved.
Reflect for a moment about our place in the universe and the epoch we live in — a universe that is roughly 13.7 billion years old. A galaxy that is some ten billion years old. A star that has shined for five billion years. A planet that has been revolving for almost as long. And us humans have called that planet ‘home’ for the last million years at the most. Humans are such a mystery. Who would have thought if they had visited Earth a million years ago and saw our forebears hunting in the forests that one day these animals would go on to design and fly rockets, would learn to travel to other planets, would learn to design microscopes that can stare at individual atoms, design radio telescopes that are sensitive enough to detect signals that have travelled for ten billion years through the vastness of space, design detectors to take a snapshot of the Big Bang itself — the Microwave Background Radiation.
And yet what gives pause is our equally stupendous propensity to self-destruct — with nuclear weapons.