A speculative equation that gives an estimate of the likelihood of discovering intelligent extraterrestrial life in the galaxy, expressed as the product of a series of factors such as the number of stars, the fraction of stars with planets, the fraction of planets on which life evolves, the average lifetime of a civilization, etc. It was formulated by the US astronomer Frank Drake in 1961.

‘He wrote an equation - now known as the Drake equation - to estimate how many alien races in our own galaxy might be trying to contact us.’

‘The other five include the Drake equation on the likelihood of us forming radio contact with extraterrestrial life, and Shannon's equations on information transmission.’

‘From an astronomical perspective, relevant factors for their existence have been identified, and the overall mathematical probability of finding them has been estimated by astronomer Frank Drake in what is known as the Drake equation.’

‘This time he takes on the Drake equation, SETI, nuclear winter and global warming alongside this critical evaluation of ‘consensus science’.’

‘I love the Drake equation: it's a real world synthesis of astronomy, geology, chemistry, evolutionary biology, and possibly psychology and sociology.’

‘With the help of a segment of the Drake equation, the number of ‘Gaias’ is estimated.’

‘Factoring that rapidity into the Drake equation, the researchers say that if there are other planets like Earth out there, odds are that at least one in three will harbour life.’

‘He does give a good description of the Drake equation and a discussion of Fermi's famous question: " Where are they?’

‘As he puts it, ‘Most equations sit at the end of a creative process…; the Drake equation, on the other hand, is just a starting point.’’

‘In the case of the Drake equation, as described in an essay by the magazine editor, it was not difficult to find things that I did not already know.’

‘Rates were calculated from the median frequency by the Drake equation.’

‘It's effectively admitting the only relevant element of Drake's notoriously arbitrary Drake equation is time.’

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