Question: Could there be aliens ??

Matthew Moore answered on 12 Mar 2015:

Yes there could be! It’s not absolutely clear how life started on this planet however, so it’s not clear what the likelihood of life occurring elsewhere could be!

Importantly, intelligence is not a definite outcome of evolution so it could be the case that there are lots of other planets with bacteria-like organisms. There are scientists that study ‘astrobiology’ which is interested in the fundamentals of life and how organisms might be different on other planets.

There is a probabilistic equation proposed by Astronomer Frank Drake which attempts to work out the likelihood of intelligent life elsewhere where:

N = number of civilisations in our galaxy with radio communication
R* = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligence
fc = the fraction of civilisations that develop technology that releases detectable signs of their existence into space
L = the length of time for which such civilisations release detectable signals into space

(N = R* fp ne fl fi fc L)

Of course all of the numbers placed into that equation would have to be guessed so it’s pretty useless in working out whether there are intelligent aliens or not :p

The assumption that there is intelligent alien life and the lack of evidence for it is called the Fermi paradox and there are a number of hypotheses which attempt to explain how there might be intelligent life but we simply haven’t come across it.

For example the SETI project actually uses radio astronomy to listen for aliens! But radio astronomy hasn’t been around that long, we haven’t even been around that long compared to the age of the planet and definitely compared to the age of the universe. Therefore if there ever has been or ever will be intelligent life elsewhere it probably wouldn’t occur at the exact same time as human civilisation on earth!