From David McKenzie, Summerhill, Tasmania, Australia
Douglas Heaven says our hunt for alien life is far from over (6 October, p 15). The frustration felt at the absence of alien life detection thus far needs tempering by a thought not mentioned. The writer Arthur C. Clarke is reported to have observed that “we are either alone in the universe, or we are not”.
We can have a definitive answer on whether there is life out there only if we detect transmissions from an exoplanet – or if someone travels here and makes a dramatic entrance. There will never be a scenario in which we can declare there is no alien life. All we can conclude is: there is no other life, or we haven't found it.
