CERN Courier magazine: January/February 2017 digital edition
Welcome to the digital edition of the January/February 2017 issue of CERN Courier
The detection of gravitational waves by the twin aLIGO detectors, announced in February last year, is one of the most significant discoveries in physics for decades. It is also further spectacular confirmation of Einstein’s theory of gravity, general relativity. Although the existence of gravitational waves had already been established from precise measurements of pulsars, their direct detection by interferometers opens a new vista on the universe. This issue of CERN Courier explores what we can expect from the new era of gravitational-wave astronomy, from understanding the internal machinery of black holes to probing the very early universe, and describes the remarkable technological feat that enabled aLIGO to detect a displacement 200 times smaller than the proton radius. We also survey the broader experimental status of general relativity, which enters its second century without any signs of cracking. Upcoming experiments at CERN’s Antiproton Decelerator are about to test the gravitational free-fall of antiatoms, while searches for extra dimensions at the Large Hadron Collider continue to place tight constraints on more exotic models of gravity. Despite being the first force to be tamed by mathematics, gravity is still riddled with enigmas. Dark energy and dark matter are among them, but perhaps the deepest mystery of all is how gravity relates to the other three forces – a challenge that has outfoxed the best minds for the best part of a century.