Astronomers estimate that there exist about 70 sextillion stars in the universe. That’s seven, followed by 22 zeroes. Some of also believe there are planets similar to Earth circling 23% of the stars. So they say, someone’s out there, we simply haven’t made contact yet. In the face of all this, Enrico Fermi asked a question begging to be answered, ‘Where’s everybody?’
The Fermi Paradox
The simple but profound question was one Enrico Fermi posed to a bunch of his colleagues over lunch. And after lunch was over, the lifelong search to answer the question started.
The Italian physicist believed that ‘any civilisation with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonise the entire galaxy’.
He went on to make the famous prediction that ‘within ten million years, every star system could be brought under the wing of empire. Ten million years may sound long, but in fact it’s quite short compared with the age of the galaxy, which is roughly ten thousand million years. Colonisation of the Milky Way should be a quick exercise.’
Sadly, Fermi died before he could study the topic further. But his enigmatic puzzle proved too irresistible for other scholars in the field of astrophysics.
One was Michael Hart, who wrote an article titled ‘An Explanation for the Absence of Extraterrestrials on Earth’ in the Royal Astronomical Society (RAS) Quarterly Journal in 1975.
Hart’s three theories were:
1) Aliens never came due to physical difficulties ‘that makes space travel infeasible’. That could be linked to astronomy, biology or engineering.
2) Aliens chose never to come to Earth.
3) Aliens visited Earth in the past, but avoided detection.
The third theory became his most popular.
We’re left alone for good reason
Now if you’re a fan of Star Trek – you’ll know the Number 1 Rule, or what the creator Gene Roddenberry termed as the ‘Prime Directive’ – not to interfere with the development of other civilisations. The civilisations were those at an extremely primitive level, so we were prevented from influencing their progress with superior tech.
Similarly, supporters of this view believe that we are haven’t heard from aliens for a deliberate reason – that they want us to evolve on our own. Known as the ‘zoo hypothesis’, it suggests that intelligent terrestrial life does not contact us because of the Prime Directive.
But that doesn’t mean that an advanced civilisation is not actively visiting Earth or keeping us in close watch. They may just be unrecognised.
Others though, reject this school of thought. They believe we are not listening and looking properly.
‘Hello, did you hear what I just said?’
Our Earth and Sun are relatively young compared to the rest of the known universe.
Much more older stars and planets exist, which in theory, suggests the existence of civilisations far more advanced than our own.
This argument goes that at any point of time, no other civilisation will be using the same technology, or within distance of making contact. Based on that, sceptics argue that practically speaking – it would be impossible for ET to phone home.
To add to the problem is the sheer size of radio search needed to seek out signals, essentially, one must cover the entire known universe. The SETI Institute estimates that even using one of their most advanced radio telescopes, the Arecibo Observatory, Earth’s television and radio broadcasts remain detectable only up to 1/10 the distance to the nearest star.
Will we ever know?
More than ever today, leaps in technology drive the quest into outer-space. They range from the hopeful – that aliens are looking for us, to the pragmatic – that SETI needs to cast an even wider net with its broadcast frequencies.
For the moment though, it’s all still white noise.
Well, what do you think? Where is everybody?