Some people say that it would be arrogant to think that humankind is the only intelligent life in the universe, but this is is not a matter of emotion, rather one of sccience – and the science is complicated.
In a recent article, Astronomer Royal Martin Rees wrote:
“We know too little about how life began on Earth to lay confident odds. It may have involved a fluke so rare that it happened only once in the entire galaxy. On the other hand, it may have been almost inevitable, given the right environment. In the next two decades we can expect progress in understanding the biochemistry of life’s origins: this is one of the great unsolved problems – fascinating to the most Earth-focused biologist, but also crucial in guiding astronomers on how and where to search for alien life.”
I am impressed by the argument of Enrico Fermi which Rees summarises as follows:
“The great physicist Enrico Fermi famously argued that advanced life must be rare. Many stars are a billion years older than our sun. Life, were it common, would have had a head start around these more ancient stars. Why then, Fermi argued, haven’t aliens already come here? Why aren’t their artefacts staring us in the face?”