Gravitational lensing is the bending of light as it passes a heavy object such as a black hole. One effect is that a star may appear brighter in the sky as is passes behind a black hole. There is known to be a supermassive black hole at the centre of our galaxy.

Theories involving extra dimensions of space also affect gravity’s variation with distance, and it is possible that observations of a star’s brightness as it passes behind the supermassive black hole would be able to measure this. The main effect of extra dimensions is that the gravity should be “stronger than expected” close to the black hole, meaning that the star would brighten more than expected.

In the case of a particular star due to pass behind the supermassive black hole in 2018, the extra brightening could be as much as 44%, but the faintness of the star means that the observation is on the borderline between being possibility and impracticality.