KAONS INSIDE SUPERNOVAS. K mesons (kaons) are exotic, short-lived particles of interest not just to high-energy physicists but also to astrophysicists since the behavior of K's inside dense nuclear matter can place severe constraints on the dynamics of supernova explosions and the stability of neutron stars. Recent experiments at the GSI lab in Darmstadt, Germany (Peter Senger, 011-49-6159-712-652, p.senger@gsi.de) have looked for K's in violent collisions between gold nuclei (at a beam energy of 1 GeV/nucleon). In those collisions, the reaction zone is compressed to about 3 times normal nuclear density for a very short time, about 5 x 10^-23 sec. Then, this nuclear fireball explodes and the gold nuclei disintegrate. During the hot and dense phase, strange mesons---mostly positively charged kaons---are created. These emerge preferentially out of the plane of the collision; apparently the high density of the reaction zone offers the kaons nowhere to escape but up or down. The pattern of kaon trajectories indicates that the effective mass of the kaon is altered in the extreme nuclear environment, in line with other experiments. These data have been explained by the suggestion that anti-kaons "condense" at nuclear densities above 3 times normal nuclear matter density. As a consequence, one can predict that a star with a 1.5-2 solar-mass iron core will not subsequently be able to sustain itself as a neutron star following a supernova explosion but would instead collapse into a black hole. (Y. Shin et al., Physical Review Letters, 24 Aug.)