The Search for E.T.

The Search for E.T.

It’s been a while since I last posted on the blog, I’m definitely due for another. I thought this time I would talk about the possibility and the search for intelligent extra-terrestrial life.

 We have been searching for extraterrestrials since the start of the space race, while the possibility of intelligent aliens had been raised long before that, it was only during the cold war that technology really began to allow us to look to the skies and search for other beings. But what is the theory behind the search for intelligent life? What do the astrophysicists think?

 Some high profile astrophysicists like Carl Sagan and Stephen Hawking believe that statistically intelligent extra-terrestrials must exist anywhere else other than earth. With the universe as large as it is, they argue, it is impossible that intelligent life doesn’t exist anywhere else.

 The famous Drake Equation helps to show this. First put forward by Frank Drake in 1960, the equation goes:                  N = N* x fp x ne x fl x fi x fc x L / MW        where N is the number of  extraterrestrial and communicating civilisations in our galaxy, N* is the number of stars in our galaxy,  fp is the fraction of stars with planets around them,  ne is the number of those planets around the stars that are capable of sustaining life,  fl is the fraction of those planets on which life evolves, fi is the fraction of those planets on which intelligent life exists, fc is the fraction of those planets on which communicating intelligent life exists, L equals the length of time that those civilisations are broadcasting (for us it is ~100 yrs  – since the advent of radio), and MW equals the lifetime of the Milky Way.

 The thing is that all these values, with the exception of L, are negligible since they cancel each other out. With N* x fp x ne x fl x fi x fc thought to approximately equal MW. L is the linchpin, the whole equation boils down to N=L, meaning that the number of advanced civilisations in the galaxy is approximately equal to the broadcasting lifetime of any such civilisation. Here is the dilemma; what the hell is L? Well based on our civilisation it is about 100 years so far, but then again, look at how close we’ve come to disaster so far i.e. the Cuban missile crisis, and there are many future threats, like global warming, and manbearpig… So, what’s the conclusion, well, nobody knows, L could be anything between 100 years and infinity, even possibly less than 100 years. Therefore depending on how long the civilisations communicability lasts for, there could be many others out there currently or we could be all on our own. There is a great video by Carl Sagan on  the Drake Equation on Youtube: <> which really explains this well, I highly recommend it.

 Of course there are also other arguments against the existence of others in outer space. The Fermi paradox, first proposed by Enrico Fermi in 1950, asks that if there ARE intelligent lifeforms on outer space then why haven’t they contacted us yet?

 There are also outlying, but still significant hypotheses like the the Zoo hypothesis. The zoo hypothesis puts forward that Earth is an artificially created environment manufactured by aliens for the purposes of experimentation (i.e. the Hitchhiker’s Guide to the Galaxy). Thus the reason why we have not encountered any communication from other intelligent civilisations is because they have have set up barriers blocking us from seeing them.

 The fascinating thing about astrobiology is that these are all considered valid arguments and the debate is lively and ongoing. Since we haven’t encountered any messages from intelligent aliens or evidence of even non-intelligent extraterrestrial life the possibilities of what could or might not be out there are endless. Personally I believe and hope that there is intelligent life out there. The search continues.

For more info check out the SETI (Search for Extraterrestrial Intelligence) website, probably the best source for info on this, plus they are at the forefront of the search: <>

3 Responses to “The Search for E.T.”

  1. karismam says:

    I agree with Emma – they wouldn’t contact us knowing our history of wars and stuff – they’d want to survive!
    It’d be interesting to see what they look like, what they think of us, etc. – but unfortunately (or fortunately, depending on how you think of it) ETs will only be relegated to our deepest imaginations and sci-fi movies *sigh*

  2. Li says:

    This is an interesting topic. Theoretically, the universe is infinite and it is highly likely that organisms should be found not only on Earth, but also on other planets in the universe according to the possibility. However, we have not found it yet.

  3. Emma Bland says:

    There is another hypothesis which states that any alien civilization that is smart enough to contact us is also smart enough not to 😛