Since E.T has yet to show up on our planet, estimating the number of alien civilisations in our galaxy might seem a premature – and rather futile – exercise. But that hasn’t stopped the authors of a new study from claiming that across the entire Milky Way, there are probably just over 30, each with the intelligence and technology to make contact with other planets.
The researchers, from the University of Nottingham, arrived at this conclusion by adapting a sequential method developed by the astronomer Frank Drake in 1961. First, they estimated what proportion of stars in the Milky Way are more than five billion years old (the assumed minimum period in which intelligent life can develop). Next, they calculated how many of those stars would be dense and stable enough to host planetary systems. Then, drawing on recent findings about the distribution of exoplanets, they estimated the number of rocky planets within the habitable zones of the stars. Finally, they calculated how many of the planets capable of supporting intelligent life would be likely to still be doing so at this moment: for this, they made the conservative assumption, based on how long radio communication has existed on Earth, that intelligent civilisations only survive long enough to broadcast for 100 years.
These calculations led the scientists to conclude that there are 36 contactable civilisations in the Milky Way right now. However, they point out, our chances of making contact with any of them are slim, because the closest one is likely to be 17,000 light years away – meaning that two-way communication with it would take 6,120 years. (The Week, 27 June 2020).
My thought: Shame! I was hoping to import one or two really competent, smart, benevolent and public-spirited aliens to start all over again from scratch and set our planet right. We have, collectively, made a dog’s dinner of it here.