From Aidan Karley
You discuss propelling a probe to the planet Proxima Centuri b using a laser (15 October, p 7). Some light will unavoidably spill past the sail. If the probe travels in a straight line, this would alert any inhabitants to our location as well as our existence. This idea was explored in by Larry Niven and Jerry Pournelle in 1993.
Brechin, Angus, UK
