From Eric Kvaalen, Les Essarts-le-Roi, France
In your look at life in the universe, you say that almost all the stars that will ever exist have already been born, and they have been around long enough for life to arise on planets that orbit them. But we don’t know that they have been around long enough for life to come about in this way. We only have our own world as an example, and we have no idea how the amazingly complicated systems involved in even the simplest forms of life came about (29 June, p 33).
Unless and until someone finds a plausible scenario and calculates the probable rate at which this would occur, we must admit our ignorance on this point.
