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The Search for Extraterrestrial Life

August 10, 2007 on 3:25 pm | In Astronomy, SETI |

Humankind has long looked to the stars in the hope of finding extraterrestrial life. In the middle and late 20th century, a telescope was on every boy’s Birthday and Christmas wishlist. But in the 21st century it seems that the mysteries of the universe hold few appeals for the minds of young children. Only rare astronomical events are popular these days. But most people, who were alive at the time, can still remember that unforgettable moment when man landed on the moon on July 20th, 1969. In 1994 the rare collision of comet Shoemaker-Levy with Jupiter was also a memorable moment.

Many of us still dream of travelling to the stars. Many also believe that we are not alone in the universe. Many people have claimed to have seen UFOs (Unidentified Flying Object), which is often dismissed as just being some kind of natural phenomenon. UFOs from ‘outer space’ have kept us interested in searching the stars for signs of life. There is documented evidence that people have claimed to have seen UFOs as far back as 1492.

But it wasn’t until 1992 that Nasa initiated a radio astronomy programme to be called SETI (Search for Extra Terrestrial Intelligence). A year later it was shut down by Congress however the search for life in our galaxy and in the star continues today across the globe. But are there really alien civilizations out there? Just waiting for us to make contact? Or are we all alone in the vast expanse of the universe? a rock of life floating amid the debris of the big bang?

There is a well known story that in 1950 physicist Enrico Fermi was eating lunch with his fellow physicists Emil Konopinski, Edward Teller and Herbert York at the Fuller Lodge, Los Alamos, New Mexico, US. According to Konopinski: “The topic being discussed was evidence of flying saucers. There ensued a discussion as to whether the saucers could somehow exceed the speed of light, and it was then that Fermi surprised us with the question: ‘But where is everybody?’” This question become known as Fermi’s Paradox and would divide the scientific community. Fermi realised that any civilisation with a modest amount of technology could rapidly colonise the entire Galaxy. Within a few million years, every star system could be brought under a single empire. This may sound a long time but in fact it’s quite short compared to the overall age of the Universe, which is about ten thousand million years old. If aliens were real, they would have had more than enough time to colonize the Galaxy.

But there is no clear indication that aliens are out there. This prompted Fermi to ask an obvious question: “Where is everybody?” Fermi believes that the fact that aliens don’t seem to be walking around our Galactic neighbourhood implies that there are no extraterrestrial anywhere at all in the Galaxy is considered to be a radical conclusion by some researchers.

In many ways, it is very difficult to imagine that we are alone in the universe. According to the Drake equation there are probably hundreds of thousands of alien civilisations in our Galaxy alone. The main purpose of the Drake equation is to quantify the uncertainty of the factors which determine the number of extra-terrestrial civilisations in the galaxy. In response to Fermi’s Paradox, many scientists believe that the reason humans have not made contact with aliens lies in our culture and the way we think.

We have no conception about how other cosmic civilisations are organised and how they look at our civilisation. We are a Type Zero civilization. Maybe we can answer these questions when we develop into a Type 1 civilization. So what are these civilization ‘types’? In 1964 astronomer Nikolai Kardashev proposed a method for classifying how advanced a civilisation is. He called it the Kardashev Scale and he classified each civilisation into three types: Type I, a civilisation capable of harnessing all of the power available on a single planet; Type 2, which is a civilisation able to harness all of the power available from a ✰; and Type 3, a civilisation capable of harnessing the power available from a galaxy.

Over the years scientists have come up with a number of solutions to Fermi’s Paradox, but one of the most surreal is the Cosmic Quarantine Theory, put forward by cosmologist Edward Harrison. He suggests any alien civilisation bent on the intensive colonisation of other worlds would be driven by a territorial impulse. But such an aggressive nature would likely not fit with the immense technological prowess required to create interstellar travel. Such a civilisation would probably self-destruct long before it could reach for the ✰.

The most evolved civilisations in the star would notice any world that showed signs of a campaign of galactic conquest and destroy it. But we may be the highest evolved civilization throughout the star. Maybe humankind will tire of waiting to hear from ETs and begin a colonization process of its own. According to the theory of relativity we can’t travel faster than the speed of light. The trip to the nearest star would take at least eight years and a trip to the center of the galaxy would take about a hundred thousand years. In science fiction they overcome this by warping, or traveling through alternate dimensions. We dont have that ability.

In the theory of relativity you can travel back in time if you can travel faster than the speed of light. But there is one way that humans could colonize space without having to travel for hundreds of thousand of years: Von Neumann machines, or probe, meaning a self-replicating spacecraft.

Humankind could send out self-replicating spacecrafts to neighbouring star systems where it could extract raw materials from asteroids to create replicas of itself. These replicas would then be sent out to other star systems. But even if we do receive a signal from the star we should be wary of answering it until we have developed a bit further. We might be better off not meeting an advanced civilisation at our present stage of development.