If aliens are out there, they’re probably all dead

9 Jun 2016

Offering a pessimistic view for those hoping that we’ll one day make contact with extraterrestrials, a new research paper proposes that if life was born on exoplanets, it likely lived fast and died young.

For nearly a century, humankind has devoted significant efforts to use the limits of its scientific ability to help find possible intelligent alien life in the universe, yet so far we’ve heard bupkis, zilch, nada.

After all, the universe is a huge place and while we were once teased with the Wow! signal back in 1977, nothing else that we have come across suggests there is intelligent alien life comparable to ourselves, at least within a few light years.

Future Human

Live fast, die young

The reason for this, according to a new paper published in the journal Astrobiology, is the rather sad reality that we are an anomaly and that fleeting life followed by a quick extinction is probably the norm.

Describing their latest predictive model as the ‘Gaian bottleneck’, researchers Aditya Chopra and Charles H Lineweaver suggest that due to a planet’s earliest habitable conditions being rather unstable, the birth of life would quickly be followed by its demise.

Citing the example of our nearest neighbours – Mars and Venus – the pair said that, despite all three having a similar upbringing in their first billion years, both planets veered off in opposite directions, with one cooling rapidly, and the other heating.

Gaian bottleneck

The Gaian bottleneck model. Image via Chopra and Lineweaver

Earth was an anomaly

Their model even suggests that while Earth inhabits the fabled ‘Goldilocks zone’ of being neither too hot nor too cold, runaway freezing or heating might be similar planets’ default fate.

Thankfully for all of us and every other lifeform on Earth, it’s believed that the evolution of microbial communities might have been strong enough to prevent the carbonate-silicate weathering cycle that typically leads to the death of life on a Goldilocks-zone planet.

The pair also challenges the commonly held belief that once the right physics ingredients are in place on a planet, it is likely that life exists there, such as when liquid water is present or it being the right distance from a local star.

‘Universe is under no obligation to prevent disappointment’

“Although, the cottage industry of habitable zone modellers can turn various knobs that control atmospheric and geophysical properties to stabilise planets over short timescales, they have mostly ignored the role of biology in keeping planets habitable over billions of years,” the pair wrote in a piece for The Conversation.

“This is in part because the complexities of interactions between microbial communities that keep ecosystems stable are not sufficiently understood.”

While the pair said they admire the work of organisations like SETI, the sole purpose of which is to search for intelligent life in the universe, they emphasise that there is no evidence for life with intelligence comparable to ours.

Additionally, they seem to suggest that wider philosophical discussions on life in the universe cloud our scientific judgement and the harsh reality that life is quickly extinguished.

“Our suggestion that the universe is filled with dead aliens might disappoint some, but the universe is under no obligation to prevent disappointment,” they said.

Dead planet image via Shutterstock

Colm Gorey was a senior journalist with Silicon Republic