I am not going to attempt to prove my point by citing un-provable sightings of UFOs or alien landings. I am going to use simple reason and logic.
In 1961 a professor at Cornell by the name of Frank Drake worked out an equation designed to calculate the probability of there being other intelligent civilizations out there in the cosmos.
This equation is:
N = N* fp ne fl fi fc fL
In this equation N* represents the number of stars in the Milky Way galaxy (currently estimated to be between 100 and 400 billion), fp is the fraction of stars that have planetary systems around them (estimated to be 20-50%), ne represents the number of planets per star capable of sustaining life (estimated to be 1-5), fl is the fraction of ne where life actually evolves (estimated to be anywhere between 100% to down close to 0%), fi is the fraction of fl where intelligent life evolves (here you must consider that intelligence is a great survival advantage, and so will most likely evolve in a race given enough time), fc is the percentage of fi where civilisations have to means and desire to communicate (estimated to be 10-20%) and fL is the fraction of the planet’s life during which the civilisation survives.
Using this equation, even with the lowest logical inputs, the number of intelligent civilisations in the Milky Way galaxy ranges from hundreds to millions.
This is, needless to say, a staggering statistic. The question then becomes not Is there intelligent life in the galaxy?’, but Will we ever encounter these other intelligent races?’
Space is, both unfortunately and fortunately, big. It is spacious. It is actually quite hard to imagine just how unbelievably gigantic it is. The Milky Way galaxy alone is 100,000 light years in diameter (a light year is the distance light can travel in a year, approximately 9,500,000,000,000 kilometres), and we are just one of billions of galaxies.
Astronomer Carl Sagan estimatedthat there are as many as ten billion trillion planets in the universe, a number that is beyond imagining. However, what is equally beyond imagining is how lightly they are scattered throughout the universe. Sagan wrote that if we were randomly inserted into the universe, the chances that you would be on or near a planet is less than one in a billion trillion trillion’. In scientific notation terms, that’s 10 to the power of 33, or 1 followed by 33 zeroes.
The average distance between stars in the cosmos is more than 30 million million kilometres. Our closest star, Proxima Centauri, is 4.3 light years away. Beyond that, the next closest star is Sirius, which is another 4.6 light years away.
So although it is possible that aliens travel billions of kilometres to draw circles in corn fields or anal probe some farmer on a back road in Wisconsin (as author Bill Bryson wrote they must have teenagers after all’) but it does seem colossally unlikely.
The chances that we will encounter another intelligent race during are altogether fleeting existence is extremely unlikely. According to the statistics there almost certainly is other intelligent life in the universe, but we are, for all practical purposes, alone.
In astronomical terms, 200 or so light years is not a great distance. But it may, quite literally, be beyond us.