A Diamond as Big as the Ritz

Life expectancy 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 (wilczek@mit.edu, 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 News Select)