Is humanity unique and alone in the vast Universe? This question, summed-up in the famous Drake equation, remains one of the most intractable and uncertain in science. Now a NASA astronaut has revealed his thoughts on the alien life riddle.
The Drake equation is the probabilistic argument used to estimate the number of intelligent extraterrestrial civilisations in the Universe.
Dr James Pawelczyk, a NASA astronaut who flew aboard the 1998 NASA STS-90 Space Shuttle mission is confident about the odds of finding extraterrestrials.
He told Express.co.uk: “If you run the Drake Equation and you basically ask ‘what is the number of galaxies in the Universe?
“These galaxies have solar systems, and a proportion have planets and the proportion of those might posses the conditions that would be favourable to life.
“By starting with a number approaching infinity and then knocking it down with proportions, you still end up with a really large number.
“So the likelihood there are these habitable zones somewhere in the Universe is quite high.
“So I think the answer to that is ‘yes’, alien life exists somewhere.”
But Dr Pawelczyk, who spent nearly 16 days in space, then preceded to flip the question around.
He said: “Let’s of the sake of argument, assume the converse and say ‘no – this is the only planet in the entire Universe where life evolved.’
“Even though we do not definitively know the answer, either answer is equally profound.
“It is a wonderful one to attempt to sort out, which one is right.”
What is the Drake Equation?
First proposed by radio astronomer Frank Drake in 1961, the Drake Equation calculates the number of communicating civilizations by multiplying several variables.
The Search for Extraterrestrial Intelligence (SETI) usually expresses the equation as:
N: The number of civilisations in the Milky Way galaxy whose electromagnetic emissions are detectable.
R*: The rate of formation of stars suitable for the development of intelligent life.
fp: The fraction of those stars with planetary systems.
ne: The number of planets, per solar system, with an environment suitable for life.
fl: The fraction of suitable planets on which life actually appears.
fi: The fraction of life bearing planets on which intelligent life emerges.
fc: The fraction of civilisations that develop a technology that releases detectable signs of their existence into space.
L: The length of time such civilisations release detectable signals into space.