CHILLING MIRRORS WITH LIGHT. In astronomy the effect of atmospheric turbulence on the quality of images acquired by ground-based telescopes can be greatly reduced by "adaptive optics", a corrective process in which parts of the telescope mirror are flexed mechanically by piezoelectric motors in an amount typically equal to a fraction of the wavelength of the incoming light. In interferometric measurements adjustments in mirrors are also desirable, not because of turbulence in the intervening medium but because of thermal noise in the mirror itself. The LIGO and VIRGO interferometers (Update 442), searching for gravity waves, need very still mirrors, the better to observe the flexing of space-time on a scale far smaller than the size of an atom. A new technique might help in this regard. Physicists at the Ecole Normale Superieure and Université P. et M. Curie in Paris (Antoine Heidmann and Michel Pinard, heidmann@spectro.jussieu.fr, 011-33.1-4427-4405), can measure the thermal agitation of mirrors and reduce this unwanted noise by a factor of 20, with pressure from laser light. This corresponds to a spatial sensitivity of the mirror at a level of a billionth of an angstrom. (P.F. Cohadon et al., Physical Review Letters October 18; see figure at Physics News Graphics.)