Number 254 (Story #1), January 11, 1996 by Phillip F. Schewe and Ben Stein DID NEUTRINOS KILL THE DINOSAURS? Massive collapsing stars radiate most of their binding energy (about 10**53 ergs) in the form of neutrinos. The rate of such collapses in our galaxy is expected to be greater, perhaps by a large factor, than the supernova rate. John Bahcall estimates a rate of about one collapse every 11 years in our galaxy. Stellar collapses might not exhibit the conspicuous optical show of full-blown supernovas but can still be potent emitters of neutrinos. According to Juan Collar, recently of the University of South Carolina but now with the University of Paris (collar@gps.jussieu.fr), stellar-collapse neutrinos may have played a role in biological extinctions on Earth in past eras, notwithstanding their very weak interactions with ordinary matter. Although stellar collapse parameters are poorly known, Collar has ventured to calculate the effect of a hypothetical low-dose, high- linear-energy-transfer (the energy dissipated by a radiation per unit length through a biological sample) neutrino flux on terrestrial animals; he suggests that collapse neutrinos may well cause a catastrophic level of cancerous malignancy, with ensuing large- scale loss of life, at a frequency (on the order of 100 million years) consistent with known major extinctions on Earth. (Juan I. Collar, Physical Review Letters, 5 February 1996; science journalists can obtain the article from AIP Public Information, physnews@aip.org.)