In my previous posts I have limited our search for life within our solar system, looking at Mars, Jupiter and Saturn. In today's installment we leave our neighbourhood and examine the rest of our galaxy, the Milky Way.

"What do we need to know about to discover life in space?"

How can we estimate the number of technological civilizations that might exist among the stars? While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake conceived an approach to bound the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.
-- Frank Drake, 1961

Source

The Drake Equation

In 1961, following a meeting held by Dr Frank Drake at the Green Bank facility in West Virginia, Drake formulated the now infamous Drake Equation - seen below.

Drake proposed the equation not so much to quantify how many intelligent civilizations there might be in our galaxy, rather to stimulate scientific discourse on the subject. Nevertheless, by using conservative figures he estimated that there could theoretically be at least 1000 civilizations within our galaxy alone.

There is much conjecture surrounding the theoretical equation but by using even ultra conservative numbers, and taking into account the advancement in our knowledge through science and technology in the decades since, one still arrives at positive results.

SETI

The Search for ExtraTerrestrial Intelligence (SETI) is a term used describing scientific searches for intelligent extraterrestrial life by means, for example, of monitoring radio waves. The first such search was funded with a $71,000 grant by the National Science Foundation and took place in 1957. Upon a 20 acre plot a flat plane radio telescope, equipped with a parabolic reflector, was built at the Ohio State University. It was nicknamed 'Big Ear' and was tasked with scanning the cosmos in the hope of receiving powerful radio transmissions from distant worlds. It would later go on to become the world's first continuous SETI program.

The Ohio State SETI program found fame in 1977, when a project volunteer, Jerry Ehman, witnessed an extremely strong signal received by the telescope. He circled the indication on a printout and quickly scribbled the exclamation "Wow!" alongside it. Dubbed the Wow! signal it was, until recently, considered by some to be the best candidate for a radio signal emanating from an artificial extraterrestrial source ever discovered. Despite addition searches since it has not been detected again and the current theory is that the signal was caused by a comet passing in front of the radio telescope.

To date no other signal from an advanced species has been received or detected on Earth. The hunt for a needle in a haystack is simple in comparison when you consider that within our galaxy alone there are an estimated 100 - 400 billion stars. Using our own solar system as reference, there could possibly be in the order of between 800 billion and 3.2 trillion planets out there. Granted not all of them would be habitable but even a fraction of that number yields millions of potentially habitable planets upon which life could have taken root and advanced to create civilizations.

Over the decades the various SETI programs have scanned billions of radio frequencies from across 100,000 light years of space occupied by 100 - 400 billion stars, around which orbit hundreds of billions of planets - without success. Why is this?

• One potential answer is that there is no other intelligent life out there - but given the staggering number of potentially habitable planets there are - it seems highly unlikely that the Earth and it's wonderful diversity of life and cultures is a fluke.

• Maybe we are the most advanced civilization in our galaxy and others just have not caught up and invented their own radio technology?

• Could it be that we are late to the party and vastly advanced species have moved onto technology we cannot comprehend?

• Maybe there are no more civilizations out there - they died out or were victims of some catastrophe. Could they have annihilated themselves, much like we seem intent on doing, long before we arrived on the scene?

• Finally, what if they are there but are just avoiding contact with the primitive warmongering ape-man?

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I would like your thoughts in the comments below. Do you believe there is intelligent life elsewhere in our galaxy?

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Source 1, 2, 3, 4, 5, 6, 7

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