is not the same for all quarks. The "strange" quark, for example,
is very unstable compared to the "up" and "down"
quarks. However in the exotic high-density environment inside a neutron
star, strange quarks are expected to fare better.
A new study conducted
by Krishna Rajagopal and Frank Wilczek at MIT (firstname.lastname@example.org,
617-253-0284) shows how much better. Previously it was thought that
the quark-matter collective (what you get by compressing matter to extraordinary
densities, as the RHIC accelerator, but keeping it cool) consisting
of up quarks (each with an electrical charge of +2/3), down quarks (charge
-1/3) and a smaller number of strange quarks (charge -1/3) would have
an overall positive electrical charge. This in turn was expected to
attract electrons, making the quark glob metallic and opaque.
The MIT calculations
show, however, that the strange quark population to be on a par with
the ups and downs, meaning the quark-matter part of the neutron star
would be electrically neutral; it would in fact be a transparent insulator
free of electrons. "Thus it seems likely," says Wilczek, "that
inside each neutron star is a 'Diamond as big as the Ritz,' actually
much bigger, and a million billion time as dense." The core would
not be a solid or crystal in the usual sense, and would not have facets,
but it would reflect some light at its boundaries and would otherwise
look like a diamond. (Physical
Review Letters, 16 April 2001; text at Physics