Number 134 (Story #2), June 24, 1993 by Phillip F. Schewe and Ben Stein AN EXPLANATION IS EMERGING FOR SONOLUMINESCENCE , the mysterious underwater phenomenon in which air bubbles, compressed by sound waves, implode, releasing 50-picosecond flashes of light which are up to a trillion times more concentrated in energy than the initial sound waves. A new round of experiments and calculations over the last year has done much to elucidate the details of the phenomenon. C.C. Wu and Paul Roberts of UCLA propose (in the 31 May Physical Review Letters) that the mechanism for sonoluminescence consists of spherical shock waves generated in the collapsing bubble. According to the hypothesis, the shock waves travel to the bubble's center at supersonic speeds, compressing air inside the bubble and heating it to such high temperatures (over 5000 K) that a plasma is formed. Electrically charged particles in the plasma release flashes of light in the process of accelerating. (The Sciences, July/August 1993.)