The Truth is Out There

I am indebted to Carol Harris for pointing out that today is World UFO day. She says, “The day aims to raise awareness about unidentified flying objects and the potential existence of intelligent life beyond earth.  The date, 2 July, commemorates the famous Roswell incident of 1947, when an alleged UFO crash-landed in Roswell, New Mexico.”

Why Alien's Haven't Landed

Personally, I don’t believe that aliens have visited the Earth. There are a number of reasons for thus-far lack of ‘first-contact’.

Star Trek neatly dodges the issue with the “Prime Directive” that civilisations capable of interstellar travel agree not to interfere with developing planets until they discover Warp Drive.

I think there is a much more likely scenario as pointed out by Douglas Adams in ‘The Hitchhiker’s Guide to the Galaxy’:

"Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.

Humanity has been producing radio waves for around 100 years which have been travelling out into space at the speed of light. This means that our presence is only visible to a distance of 100 light-years (A light-year is simply the distance a beam of light travels in a single Earth year - approximately 9.5 trillion kilometres). There are around 60,000 stars within 100 light-years of Earth. Our galaxy, The Milky Way, contains between 100 and 400 billion stars and is about 100,000 light-years across. We are only visible to alien civilisations on our doorstep.

Even if some alien astronomer did discover us, it takes another 100 years to reply. The fastest space vehicle ever built by humans is NASA's un-crewed Parker Solar Probe at around 400,000 kph. This would take about 1,547 years to travel just 1 light year.

Do Aliens Exist?

The observable universe contains an estimated 2 trillion galaxies. Even if the emergence of intelligent life is unimaginably unlikely, given the number of planets I feel sure aliens exist somewhere. They’re just too far away.

Many scientists think life is relatively commonplace. In 1961, astronomer Dr. Frank Drake gathered a group of scientists to talk about how many alien civilizations could be living in our galaxy. He wrote an equation which predicts the number of intelligent alien civilizations in the Milky Way Galaxy.

R* x FP x Ne x FL x FI x FC x L = the number of intelligent aliens currently living in the Milky Way

1)     R* - rate of star formation. The number of stars made in the Milky Way galaxy in one year, 

2)     Fp - the fraction of stars that have planets,

3)     Ne - the fraction of those planets where life can exist,

4)     FL - the fraction of those planets where life does exist

5)     FI - the fraction of those planets where intelligent life exists, 

6)     FC - the fraction of those intelligent aliens who develop technology that is able to communicate outside of their own planet, 

7)     L - number of years an intelligent, communicating civilization lasts.

These can only be educated guesses but according to Arizona State University some reasonable figures are:

1)     R* = 10 (astronomers know roughly 10 stars are made per year)

2)     Fp = 100% (nearly all stars have planets)

3)     Ne = 25% (life can exist in very harsh environments - it would make sense that life could exist on a number of planets)

4)     FL = 100% (if life can exist, it will)

5)     FI = 1% (not all life will become intelligent)

6)     FC = 50% (most intelligent life will be able to invent communication technology such as radio)

7)     L = 1,000,000 years (intelligent life will exist for a long time)

This works out at 12,500 intelligent alien civilizations which may currently exist amongst the 100 - 400 billion stars in our galaxy. Much harder than finding a needle in a haystack.

In the words of Eric Idle,

“So remember, when you're feeling very small and insecure How amazingly unlikely is your birth And pray that there's intelligent life somewhere out in space 'Cause there's bugger all down here on Earth!”