From Adrian Ellis
In your article on a new strategy for those involved in the search for extraterrestrial intelligence (SETI), David Messerschmitt says that alien civilisations would logically choose to send short, wide-band radio signals rather than prolonged narrow-band ones, to improve both energy efficiency and bandwidth (31 January, p 17).
Yet probably the most important signal so far detected by SETI is the narrow-band “Wow!” signal, picked up in 1977. It came from the direction of Sagittarius and was almost exactly on the hydrogen line, a frequency many thought would be ideal for interstellar transmission. Should we tell the alien civilisation in Sagittarius that they’re being a bit primitive?
Hampton, Middlesex, UK
