PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 512 November 15, 2000 by Phillip F. Schewe and Ben
Stein
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. (Physical Review Letters, 27 November 2000; Select
Articles.)
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