Supernova Suggests Einstein's Speed of Light Needs Recalculating

The most counterintuitive, surprising, and impactful new stories delivered to your inbox every Thursday.

What’s the Latest?

Observational evidence gathered from a supernova blast has some physicists arguing that the constant for the speed of light, first calculated by Einstein, is in need of updating. In 1987, when a detector far beneath Italy’s Mont Blanc registered a sudden burst of neutrinos, physicists were puzzled as to why the corresponding photons arrived some 7.7 hours later. “Neutrinos and photons both travel at the speed of light and should therefore arrive simultaneously, all else being equal. The mystery is what caused this huge delay of 7.7 hours between the first burst of neutrinos and the arrival of the optical photons.”

What’s the Big Idea?

Physicist James Franson at the University of Maryland in Baltimore has published new calculations that account for the laws of quantum mechanics as light travels through a field of mass as large as the Milky Way galaxy. “He says that quantum mechanical effects should slow down light in these kinds of circumstances and calculates that this more or less exactly accounts for the observed delay.” According to Franson, the speed of light is slower than what Einstein calculated because the gravitational potential of the galaxy works on light photons, which have mass, to slow them down over great distances.