Einstein has passed his toughest test yet: his theory of general relativity holds up even in the extreme conditions surrounding a pair of pulsars.
“If general relativity does break down, we believe it will be in regions of very strong gravity,” says Michael Kramer of the Jodrell Bank Observatory in Macclesfield, UK. Pulsars, which are dense neutron stars, create massive gravitational fields, and their beacon-like radio emissions can be tracked from Earth.
Until now, only binary systems containing a pulsar and an unseen companion had been studied. Kramer’s team looked at a double pulsar system known as PSR J0737-3039A/B, which…
