The new supermassive black hole image just validated a key prediction of Einstein
Recently, scientists released the first image of Sagittarius A*, our galaxy’s supermassive black hole.
It is the Event Horizon Telescope (EHT) team’s second black hole snapshot, following the release of a picture of MH7* in 2019.
Dimitrios Psaltis, professor of astronomy and physics at the University of Arizona, and one of the primary scientists behind the new accomplishment, has explained how the new image proved one of Einstein’s predictions from his theory of gravity.
It all comes down to the stunning similarities between Sgr A* and MH7, despite their vast size difference – Sgr A, which has a mass four million times that of our Sun, is over a thousand times smaller than M87*.
Black holes break nature’s scale law
More than 300 international scientists, support workers, and eight radio observatories throughout the world contributed to the black hole observations. They might not have been possible, however, if it hadn’t been for a seminal work released in 2000 by EHT Science Council members Feryal zel and Dimitrios Psaltis, both from the University of Arizona, that offered an outline for how to photograph one of the celestial giants.
According to Psaltis, the new image of Sgr A* has proven one of Einstein’s theory of gravity’s most fundamental predictions, according to a statement from the University of Arizona. The new evidence, in particular, shows that the picture of a black hole scales only with its mass. In other words, a black hole 1,000 times less massive will seem quite similar; the only real change will be size.
“In general, small things typically look very different from big things, and that’s no coincidence,” Psaltis said. “There is a good reason an ant and an elephant look very different, as one has a lot more mass to support than the other.”
This is related to the law of scale in nature, which says that when two entities are substantially different in size, they usually appear highly different to one another. Black holes, on the other hand, scale while appearing the same.
As Psaltis puts it, comparing the new image of Sgr A* to the 2019 image of M87* validates Einstein’s theory that black holes appear to be the only objects in the universe that obey only one natural rule – gravity. “The fact that the light appears like a ring, with the black shadow inside, tells you it’s purely gravity,” Psaltis said. “It’s all predicted by Einstein’s theory of general relativity, the only theory in the cosmos that does not care about scale.”
The universe is full of almost identical ‘donuts’
The EHT team will continue to image and even record black holes now that we can observe Sgr A* and M87* in order to obtain a better knowledge of the cosmic giants and reveal more of their strange behaviors to the world.
Psaltis says that “wherever we look, we should see donuts, and they all should look more or less the same.”
“The reason this is important – besides the fact that it confirms our prediction – is that nobody likes it,” he continued. “In physics, we tend to dislike a world where things don’t have an anchor point, a defined scale.”