Starlight behaving oddly (Image: X-ray: NASA/CXC/MIT/E.-H Peng et al; Optical: NASA/STScI)

EVER since Arthur Eddington travelled to the island of Príncipe off Africa to measure starlight bending around the sun during a 1919 eclipse, evidence for Einstein’s theory of general relativity has only become stronger. Could it now be that starlight from distant galaxies is illuminating cracks in the theory’s foundation?

Everything from the concept of the black hole to GPS timing owes a debt to the theory of general relativity, which describes how gravity arises from the geometry of space and time. The sun’s gravitational field, for instance, …