Einstein theory passes black hole test


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Artwork: The “supermassive” black hole at the centre of the Milky Way is known as Sagittarius A*

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.

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