During a NOVA program, Noble Laureate Murray Gell-Mann was asked for his thoughts on life in the universe.
His response has stuck with me: "I find the prospect that there is intelligent life on other planets terrifying but equally daunting is the thought that in this whole great universe, we are it."
Or maybe Douglas Adams put it better: "The universe is infinite in size but there are only a finite number of planets with intelligent life. As anyone who has done math knows, any finite number divided by infinity is near enough to zero so as to not matter. Therefore, any intelligent life that you meet is merely a figment of your imagination."
That is not an exact quote but it hints at a very fundamental question - is the universe filled with intelligent life? There have been many attempts to answer this question but so far no one knows the answer.
Perhaps the most famous search is SETI (the Search for Extra-Terrestrial Intelligence).
It has been monitoring radio space for about 50 years with the hopes of picking up some hint of a signal. Maybe an alien version of NOVA or the Hitchhiker's Guide to the Galaxy.
But SETI begs the question: Would we even understand an alien radio signal if we found one? There are many views on this subject. Understanding an alien intelligence - or the radio signals generated by an alien intelligence -
depends on being able to interpret their thoughts. But who is to say how they think? In words?
In pictures? In emotions?
Despite years of Star Trek and other spacefaring ventures, universal language is not likely.
It presupposes commonalities that are just not probable. I mean, how do you explain a rainbow to a species that sees in the microwave region of the electromagnetic spectrum?
There is no reason alien intelligence will be
humanoids speaking english.
That said, finding something that could be a radio signal generated by an alien intelligence is a worthwhile exercise so SETI continues.
And not finding a signal doesn't mean that there isn't intelligent life out there. Rather that it is not using radiowaves for communication during a time when we could detect them.
This is a subtle point but the window for detecting a transmission from an alien intelligence could be very small.
Consider our own history. We started broadcasting radio signals about 100 years ago. Over the last decade, we have increasingly moved away from the radio region of the spectrum.
Television is carried by cables. Communication is via the Internet. Telephones use
microwave towers.
Some experts predict that Earth will be radio silent within 50 years. That means that some alien intelligence looking for us would have to be listening at precisely the right time to intersect a bubble 150 light years wide expanding outwards from our planet at the speed of light.
They would have to be in the radiowave portion of their technological development and listening at just the right moment to catch a
signal. What are the odds?
It is to answer this question that radio
astronomer Frank Drake proposed his famous equation. He tried to calculate the probability of finding alien intelligence.
To do this, he needed certain numbers such as the number of stars with planets in orbit. The number of those planets with atmospheres.
The number with the right conditions for life.
When Drake first proposed his equation, the values assigned to the variables in his equation were, at best, guesses. In the past 50 years, we have made much progress.
For example, the Hubble Space Telescope and Canada's MOST satellite have revealed that planets around other stars are far more common than anyone thought. Indeed, astronomers argue that every star in the universe has planets about it.
That would make for a ridiculously huge number of planets. And surely some of them would be in the habitable zone. There have been tantalizing hints that astronomers may have found some of these planets already.
But, of course, what is the likelihood that they might have life?
Some researchers have argued that the number would be 100 per cent because, after all, we have only one example of such a planet that we know about and it definitely has life!
This brings us back to Curiousity. After seven minutes of terror, the probe successfully landed on the surface of Mars.
Its mission is to determine if life could have existed on Mars. And if life did.
If it turns out that the signatures of life are detectable then we would be batting two-for-two.
Two planets that could host living organisms; two planets with life.
It would certainly go a long way to supporting the notion that we are not alone in this universe.
And maybe those intelligent creatures that you meet might be real.
