IT’S one of the greatest conundrums in the universe.
Scientists believe it’s highly likely that alien civilisations exist somewhere out in deep space — so why haven’t we spotted them yet?
Now one former NASA scientist has come forward to suggest that extraterrestrials haven’t contacted Earth because they are probably living at the bottom of a frozen ocean on a distant water world.
Alan Stern, who now works at the Southwest Research Institute in Texas, gave a speech at the 2017 Division for Planetary Sciences last week to discuss the Fermi Paradox, which questions why we haven’t found aliens when it’s so likely that they exist somewhere in our gigantic universe.
“Many possible explanations [to this paradox] have been proffered,” Stern wrote.
“We suggest another — namely that the great majority of worlds with biology and civilisations are water ocean worlds.”
Aliens would have a nice life if they lived at the bottom of oceans because the water would protect them from exploding stars, spikes of space radiation or other natural disasters.
However, Stern believes that these water worlds are likely to be extremely cold, meaning that aliens are probably living beneath a thick crust of ice that makes it impossible for us to contact them.
He added: “Water worlds are naturally cut off from communication by their interior nature below a thick roof of ice or rock and ice, therefore do not easily reveal themselves.”
Stargazers believe the majority of the habitable worlds in the universe are likely to be almost entirely covered in water — which could mean the creatures that live on them are more likely to look like fish than humans.
Earlier this year, Dr Fergus Simpson from the Institute of Cosmos Sciences at the University of Barcelona used a complex form of maths called Bayesian probability to predict the surface of most planets is likely to more than 90 per cent covered in water.
However, he believes fish-like aliens are unlikely to be very advanced.
“The main reason I’m sceptical about there being lots of intelligent underwater alien species is that I think it’s harder for aquatic creatures like dolphins to use tools or build a fire.”
Of course, Earth is pretty watery itself, with just 29 per cent of the surface covered in land.
Dr Simpson suggested this unusual balance between land and water may be linked to the evolution of life on our planet.