A new experiment at Brookhaven using colliding gold ions provides surprising evidence about a fundamental concept in physics: the vacuum. It appears that you can get something from nothing, the vacuum is unstable and new particles can be spontaneously created in empty space. Gack.
A side view of one of the first high-energy collisions captured by the Solenoidal Tracker of the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The initial head-on collision of two gold ions, each consisting of a total of 197 protons and neutrons, occurs at the mid-point of the central tube (running across the image from right to left). The tracks indicate the paths taken by thousands of subatomic particles created in the fireball of energy set free in these collisions. Several layers of detectors, arranged concentrically around the central tube, and encased in a powerful magnet, allow the identification of these particles. (Courtesy of Brookhaven National Laboratory, STAR collaboration.)
