What’s the great filter?


Earlier this year, scientists announced the discovery of Kepler-186f, a planet 492 light years away.

It was notable as the first planet discovered that’s almost exactly the same size as Earth, orbiting in the “habitable zone” — the distance from a star in which we might expect liquid water, and maybe comparable life.

It also, however, increases the probability of inevitable near-term human extinction — a concept known as the Great Filter. It’s a theory that addresses the Fermi Paradox: why haven’t we met alien life, despite the existence of hundreds of billions of solar systems in our galactic neighbourhood in which life might evolve?

That we haven’t, suggests at least one of the evolutionary steps from simple organisms to interstellar civilization is exceedingly unlikely. This is why the recent search for evidence of life on Mars is significant. As philosopher Nick Bostrom pointed out, “If it happened independently twice here in our own back yard, it must surely have happened millions of times across the galaxy. This would mean that the Great Filter is less likely to occur in the early life of planets and is therefore more likely still to come.”

So does this imply that every sufficiently advanced civilisation will stumble across a suicidal technology or unsustainable trajectory? This disturbing hypothesis suggests there’s an inherent destructive tendency common to virtually all sufficiently advanced technological civilisations. Here on Earth we have survived meteor strikes, super volcanoes and naturally occurring pandemics for around 200,000 years, and also persisted through the self destruction of civilisations, from the Mayans to the Roman Empire and beyond. But a total loss of humanity hasn’t occurred. Yet. After all, we have only been living with things like nuclear weapons for a relatively short time.

Huge leaps in technologies are occurring right now and astronomers such as Sir Martin Rees at the Cambridge Centre for the Study of Existential Risk point to advances in biotechnology as being potentially catastrophic. Others, such as Stephen Hawking, have expressed serious concern about the exotic but understudied possibility of machine super intelligence.

The universe is 13.7 billion years old and many other planets are vastly older than Earth. Thousands — possibly even billions — of them should sustain cultures millions and billions of years more advanced than ours. Earth and the Milky Way are relative newcomers in the great scheme of everything, so why no sign of the intelligent life that has this massive evolutionary headstart on us?

There’s a school of thought that just as the existence of some form of life elsewhere is almost mathematically certain, given the size of the universe, so the likelihood of it having visited Earth is almost nil for the very same reason. Other advanced life is just too far away and we’re experiencing the streetlight effect (Google it).

After all, the Voyager 1 probe, in its 38th (Earth) year of travel, is now just 18 light years away from us, and that’s the farthest we’ve gone — our galaxy alone is at least 100,000 light years across.

Alternatively, the silence from the stars is a portent of inevitable doom. The biggest threat to humanity could be the very progress we are currently celebrating. Perhaps life in the universe is simply doomed to fail if it becomes too advanced, and all intelligent species become extinct before they master the technology for space colonisation.

Is it just a matter of time before we face our own Great Filter? And what would be the odds on bucking that trend?

For Esquire Magazine, December 2014

For original PDF click here The Great Filter

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