Hanbury Brown Twiss Interferometry: From the Stars, to STAR… and Back

Abstract

Seventy years ago, two radio engineers emerged from the frenzy of World War II and entered the new field of radio astronomy.Robert Hanbury Brown and Richard Twiss developed an entirely new instrument and technique, based on "correlated noise,"to measure theangular radius of previously unresolvable stars. Initially greeted with skepticism, their work led directly to the birth of quantum optics.  At nearly the same time, Goldhaber et al discovered a tiny unexpected correlation in the first true particle physics experiments; until recently, the "GGLP" effect played a minor role in particle physics.  It would take another 15 years until the connection between these apparently disparate phenomena was realized by Shuryak and others around 1976, just as the new field of heavy ion physics was emerging.  Thus did Hanbury Brown's discovery give birth to femtoscopy, the most direct method to probe space and time at the scales of 1e-15 meter and 1e-22 second.  I will discussthe structures and insights that femtoscopy has revealed in ultra-relativistic ion collisions at RHIC and the LHC and their rolein establishing the hydrodynamic nature of the quark-gluon plasma.  I will briefly discuss current progress to bring a high-energy physics approach to telescope arrays and relaunch stellar intensity interferometry with fast digital electronics and massive computing.