From John Darlington
Robert Adler reports that in the hunt for dark matter some researchers are considering the possible existence of dark atoms, dark chemistry and even dark stars and planets (31 August, p 36).
If so, there may equally well be dark aliens living ever unseen and undetectable alongside us, and who are puzzled by the 15 per cent or so of matter that is missing from their universe.
Carrick-on-Shannon, Leitrim, Ireland
