Last week's discovery of phosphine gas unsettled many assumptions scientists had about the "hell planet." But that doesn't necessarily mean there's lifeby Stephen Eales / September 23, 2020 / Leave a comment
There are big questions in science that scientists care about, and then there are big questions that everyone (well Prospect readers, at least) care about. The big two in the “everyone” category are probably: what is consciousness (and how did the life that eventually became conscious get started in the first place?) And what was the spark that turned a chemical mush into life?
The answers to both questions, of course, are in all the world’s sacred books and I have to admit that so far we scientists haven’t provided anything much more convincing. The recent discovery of the gas phosphine in the atmosphere of Venus, however, may be a major step forward to at least answering the question about the origin of life.
An equation that measured alien life
The first person to think systematically about the chance of extraterrestrial life was the astronomer Frank Drake in the early sixties. Equations are usually a way of mathematicising something we know about the world, but Drake dreamt up an equation that illustrated just how little we knew back then about the origin of life.
Drake’s equation estimated the number of intelligent alien civilisations in the galaxy. Drake started with the number of stars in the galaxy, which is roughly 300 billion. He then multiplied this by a large number of factors, two of the most important being the probability that a star has planets and—if the star does—the probability that one of the planets lies in the habitable zone in which water can exist in liquid form.
In the early sixties, apart from the number of stars in the galaxy, almost all the factors were completely unknown. We didn’t know whether any star apart from our own had planets, and the uncertainties in all the terms in the equation made it plausible that at the time, either every star in the galaxy had life around it, or that none of them did (apart from our own star, of course.)
We now know much more about most of the terms in Drake’s equation. We know that most of the stars in the galaxy…