By ROB WAUGH
Daily Mail
NASA has said there are ‘billions’ of planets in our own Milky Way galaxy – but a new study suggests that the idea that they are teeming with alien lifeforms may just be wishful thinking.
Two Princeton scientists used what’s known as ‘Bayesian analysis’ – a technque that ‘boils down’ ideas to the actual data, as opposed to scientists’ own ideas about what ‘should’ be true.
They suggest that it’s very possible Earth is a one-off aberration where life took hold unusually fast – and on the average extraterrestrial planet, the chances of life are very low indeed.
‘There is a commonly heard argument that life must be common or else it would not have arisen so quickly after the surface of the Earth cooled,’ Winn said.
‘This argument seems persuasive on its face, but Spiegel and Turner have shown it doesn’t stand up to a rigorous statistical examination — with a sample of only one life-bearing planet, one cannot even get a ballpark estimate of the abundance of life in the universe.
Deep-space satellites and telescope projects have recently identified various planets that resemble Earth in their size and composition, and are within their star’s habitable zone, the optimal distance for having liquid water.
While these observations tend to stoke the expectation of finding Earth-like life, they do not actually provide evidence that it does or does not exist, Spiegel explained. Instead, these planets have our knowledge of life on Earth projected onto them, he said.