Strangelets are Strange but not Dangerous

Strangelets are hypothetical stable or semi-stable particles which contain strange quarks. Theorists have predicted that such entities could survive for long periods inside neutron stars and might be produced in the type of heavy ion collisions going on at the RHIC machine at Brookhaven. Fears that the production of strangelets would lead to some runaway reaction in which more and more ordinary matter would be turned into strange matter, with catastrophic effects for our planet, have been largely dispelled (Dar et al., Physics Letters B, 16 December 1999; and Jaffe et al., Review of Modern Physics, Oct 2000; Select Articles) partly by pointing to the fact that nature has always been producing heavy-ion collisions in amid cosmic ray interactions.

Any remaining doubts over the strangelet danger have now been put to rest by Jes Madsen (45-8942-3670, jesm@ifa.au.dk) of the University of Aarhus in Denmark. Madsen shows that light strangelets are highly unstable, heavy strangelets are difficult to make in the fireball environment of the collision, and medium-sized strangelets must have a positive charge, which precludes (through electrostatic repulsion) their assimilating any nearby (similarly positively charged) nuclear matter into a larger agglomeration. (Madsen, Physical Review Letters, 27 November 2000; Select Articles.)