Bookmaker Paddy Power is offering odds of 16-1 that the existence of extraterrestrial life will be confirmed this year.
The
Drake equation, devised in 1961 by Frank Drake, Emeritus Professor of
Astronomy and Astrophysics at the University of California, is a
formula designed to estimate the number of detectable extraterrestrial
civilisations in our
Milky Way galaxy.
Please Note the important word “detectable”.
The
answer is the result of multiplying seven variables – the 200 billion
stars in our galaxy, the percentage of these that have planets, the
average number of life-supporting planets per star, the proportion of
these on which life develops and on which intelligent life develops, the
percentage with communication technology, and the proportion that
release detectable signals in the right time frame for us to pick them
up.
We can input values into the Drake equation, with some based on solid science and others based more on guesswork.
Until not long ago, most scientists assumed that there was no life at the bottom of the ocean because of the lack of sunlight. Yes they did.
While
about 500 humans have flown in space, only three have been to the
deepest depth of the oceans, the Mariana Trench, which lies at 10,994
metres below sea level in the Pacific.
Film director James Cameron was the most recent earlier this year.
Discoveries in the murky depths suggest we should think more broadly about the conditions in which life can develop.
Some
have suggested hydrothermal vents, which bring hot, mineral-rich water
gushing through the ocean floor, could have provided the spark that
triggered the creation of early life.
Conventional wisdom has been
that life is carbon-based and needs water, but some researchers are
doing exciting work, playing with ideas such as silicon-based life
forms.
Silicon is just below carbon in the periodic table, has some chemical similarities and is widely available in the universe.
Weeks ago, permission was given for the construction of the world’s largest optical telescope.
The
European Extremely Large Telescope, is to be built on top of a mountain in
Chile.
This
compares with the Very Large Telescope, a suite of interconnected
optical telescopes with four primary mirrors that measure 8.2 metres
across.
Then there is the conceptual design for the futuristic
Overwhelmingly Large Telescope, with a single mirror of 100 metres in
diameter.
These telescopes will allow us to probe the chemical make-up of the atmospheres of planets.
We may find unusual results such as spikes of chemicals we weren’t expecting.
Maybe we will see spikes of silicon compounds, indicating life forms.
Flowing methane and pools of methane have been identified on Titan, one of Saturn’s moons.
It makes me wonder whether a form of life could be based on liquid methane.
The
creatures we have found on the bottom of the ocean floor use thermal
energy from the centre of the Earth rather than sunlight.
This
variant on life and the other possibilities being looked at lead me to
believe we may need to extend our notion of where alien life might be
found.
It might be prudent to consider whether we are talking about friends or foes.
Stephen
Hawking said we shouldn’t send signals out into space because if there
are life forms more advanced than us it might not be wise to tell them
where we are.
I don’t believe we should be worried. If they are
very intelligent I don’t know what we have that they would want enough
to attack us.
We do have water on Earth but if they are travelling halfway across
the galaxy to find us they will bump into plenty of water on the way.
They
will probably see us as we see ants – oddities perhaps worthy of study.
I can’t see what their motive to exterminate us would be.
Using
the Drake equation, it leaves me with an estimate of four intelligent
alien civilisations in our galaxy with means to communicate and overlap
in time with humans.
Nevertheless there remains a big problem. Communicating across the galaxy is challenging.
The
Voyager 1 spacecraft, which is carrying a recording of greetings from
Earth, has been travelling through the solar system since the 1970s and
has only made it into deep space.
To get to our nearest neighbouring star, Proxima Centauri, would take it 76,000 years.
If
one of our four alien civilisations is on the other side of the galaxy
then it would take millions of years just for electromagnetic signals to
travel that distance, and by then they may be too weak to be
detectable.
The notion we constitute the only little spike of life in the universe is a lonely one.
Perhaps we can take comfort from the likelihood that there are all sorts of weird and wonderful life forms out there.
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