Ben Prather/EHT Theory Working Group/Chi-Kwan Chan
Last week, scientists unveiled to the world the first image of our galaxy’s supermassive black hole, Sagittarius A*.
It’s the second snapshot of a black hole captured by the team at the Event Horizon Telescope (EHT), which also unveiled an image of MH7* in 2019.
One of the main scientists behind the new breakthrough, Dimitrios Psaltis, a professor of astronomy and physics at the University of Arizona, revealed how the new image proved one of Einstein’s predictions from his theory of gravity.
That’s because of the striking similarity between Sgr A* & MH7*, despite their huge difference in size: Sgr A*, which has a mass 4 million times that of our Sun, is more than a thousand times smaller than M87*.
Black holes defy nature’s law of scale
Observations of the black hole were made thanks to more than 300 international scientists, support staff & eight radio observatories around the world. But they might not have been possible had it not been for a landmark paper published in 2000 by EHT Science Council members Feryal Özel & Dimitrios Psaltis, both of the University of Arizona, that outlined how to imagine one of the celestial giants .
The new image of Sgr A* has proven to be one of the most fundamental predictions of Einstein’s theory of gravity, Psaltis explained in a statement from the University of Arizona. That said, the new data proves that the image of a black hole only scales with its mass. .In other words, a black hole 1000 times smaller in mass will look very similar; The only really noticeable difference will be size.
“In general, small things look very different from big things, and that’s no coincidence,” Psaltis said. “There’s a good reason why an ant & an elephant look very different, as one has a lot more mass-to-support than the other.”
This is due to nature’s law of scaling, which dictates that two objects that are very different in size will usually look very different. However, black holes scale while looking very similar.
As Psaltis says, comparing the new image of Sgr A* to the 2019 image of M87* confirms Einstein’s theory that black holes appear to be the only objects in existence that respond to only a single law of nature: gravity “That the light looks like a ring with the black shadow in it tells you it’s pure gravity,” Psaltis said. “All of this is predicted by Einstein’s general theory of relativity, the only theory in the cosmos that doesn’t care about scale.
Universe is full of almost identical ‘donuts’
Now that we can see Sgr A* & M87*, the EHT team will continue to capture images & even video of black holes to better understand the cosmic giants and reveal more of their mysterious behavior to the world.
Psaltis says, “Everywhere we look we should see donuts, and they should all look more or less the same.”
“The reason this is important, aside from the fact that it confirms our prediction, is that nobody likes it,” he continued. “In physics we tend to reject a world where things have no anchor point, a defined scale.
