EINSTEIN'S THEORY of general relativity (GR), which describes how gravity is the result of mass, energy and the curvature of spacetime, has passed every test thrown at it since it was thought up in 1915.
But, despite its success, relativity isn’t expected to be the last word in gravity.
Although it makes superbly accurate predictions for everyday gravitational objects, relativity hasn’t been tested in more extreme circumstances.
You don’t get much more extreme than this pair. The larger object is a fairly unremarkable white dwarf star, but the smaller one, a newly discovered pulsar, is an extremely remarkable object indeed.
Imagine an object that could sit quite happily on the Isle of Wight and you could walk around in just a few hours – now imagine that bundled up inside it is enough atoms to make two Suns; its surface is burning away at millions of degrees and it shoots high-energy jets of radiations out into space at millions of miles per hour. That’s extreme.