I am now going to attempt to explain why Einstein was right. I would like to note that Einstein is usually right. But I generally leave the astrophysics to Pamela, so I’ll channel her as best I can. Here goes.

One of the biggest theories to come out of Einstein’s work was General Relativity, which basically deals with objects that are large enough to have a gravitational effect on space-time. Simply put, General Relativity is the theory of gravity.

I want to take a brief moment to remind our audience that a theory is not the same thing as a hypothesis. A hypothesis is that idea you have before you start testing and experimentation, the “maybe because” that sets you on your path. A theory has been proven correct over and over again based on data. Gravity is not going to magically stop working if you don’t believe in it.

Back to Einstein. He published his theory of general relativity back in 1915, and for the last hundred plus years, the astrophysics community has been collecting evidence that backs up that theory. I mean, people have tried to find evidence that disproves General Relativity, and it hasn’t happened. From bending light around the Sun observed during an eclipse in 1919 to this latest story, we keep collecting evidence that supports General Relativity.

And this story proves it in an extreme way. Using ESA’s XMM-Newton and NASA’s NuSTAR space telescopes, researchers observed a spiral galaxy about 800 million light-years away simply named I Zwicky 1. They were looking for information about a corona around the black hole in the galaxy that is a source of bright X-rays. The hypothesis is that the gas that makes up that corona is continuously falling into the black hole and flaring as it is heated. The gas generates magnetic fields, which subsequently are twisted by the massive gravitational effects of the black hole. When the twisting gets to be too much, the magnetic fields snap and release all the built-up energy. The high-energy electrons produce light in X-ray wavelengths.

And here’s where everything gets extremely wild and amazing. The telescopes observed a flare that signified a massive release of energy. Then, per the press release: The X-ray flare observed from I Zwicky 1 was so bright that some of the X-rays shone down onto the disk of gas falling into the black hole. The X-rays that reflected on the gas behind the black hole were bent around the black hole, and these smaller flashes arrived at the telescopes with a delay. These observations match Einstein’s predictions of how gravity bends light around black holes.

Talk about extreme proof. We knew light was bent by massive gravitational fields. Earlier this week, we presented an image that was a cluster of gravitationally lensed galaxies. This really isn’t a theory we question any longer, but to find evidence in this way — seeing reflected light get bent back at us from the backside of a black hole? That’s, well, HUGE.

Even better, since these X-ray echoes have specific wavelengths to them, we can tell by how those wavelengths change, the timing of our observations, and the location they come from in the disk what is happening at the black hole. The team wants to use this method to build a three-dimensional map of the surroundings, which is amazing since black holes are, you know, black. No light. Difficult to map.

This work was published in the journal Nature. And now the team gets to continue studying the corona as originally planned. I love accidental science. Plus, the more I learn about black holes, the more awesome and confusing they are.

More Information

ESA press release

“Light bending and X-ray echoes from behind a supermassive black hole,” D. R. Wilkins et al., 2021 July 28, Nature