The black hole at the centre of our galaxy has helped astronomers confirm a key prediction of Albert Einstein’s ideas.
By observing a cluster of stars near the hole, they were able to confirm a phenomenon known as “gravitational redshift”.
This effect applies to sources of light that are in a gravitational field.
The finding could help scientists better understand the physics of black holes.
The Very Large Telescope (VLT) in Chile found evidence for Einstein’s prediction by observing a star, called S2, that passed through the intense gravitational field of Sagittarius A* – the huge black hole at the heart of the Milky Way.
The effect they observed, gravitational redshift, describes how the wavelength of light lengthens as it climbs out of a gravitational well like a black hole.
In practice this corresponds to a shift in the wavelength to the red part of the light spectrum – hence “redshift”.
It’s predicted by Einstein’s theory of general relativity, but has never been observed in an intense gravitational field such as that of a black hole.