Black holes normally reveal themselves in astronomy because they are surrounded by discs of gas, heated to high temperatures, stolen from nearby stars. The X-rays emitted from these accretion discs give away the black hole although it cannot itself b...

... ting the space in front of it (red) and expanding the space behind it (blue). This expansion and contraction is shown by the distortion in the grid, which represents spacetime, the continuum that combines space and time. ...