![]() "Many ways to modify general relativity fail at this new and tighter black hole shadow test." "Using the gauge we developed, we showed that the measured size of the black hole shadow in M87 tightens the wiggle room for modifications to Einstein's theory of general relativity by almost a factor of 500, compared to previous tests in the solar system," said UArizona astronomy professor Feryal Özel, a senior member of the EHT collaboration. The team focused on the range of alternatives that had passed all the previous tests in the solar system. "In this way, we can now pinpoint whether any alternative to general relativity is in agreement with the Event Horizon Telescope observations, without worrying about any other details," said Lia Medeiros, a postdoctoral fellow at the Institute for Advanced Study who has been part of the EHT collaboration since her time as a UArizona graduate student. ![]() The team did a very broad analysis of many modifications to the theory of general relativity to identify the unique characteristic of a theory of gravity that determines the size of a black hole shadow. "We wondered if there was anything we could do with these observations in order to cull some of the alternatives." "At that time, we were not able to ask the opposite question: How different can a gravity theory be from general relativity and still be consistent with the shadow size?" said UArizona Steward Theory Fellow Pierre Christian. The first results had shown that the size of the black-hole shadow was consistent with the size predicted by general relativity. To perform the test, the team used the first image ever taken of the supermassive black hole at the center of nearby galaxy M87 obtained with the EHT last year. "This is a brand new way to test general relativity using supermassive black holes," said Keiichi Asada, an EHT science council member and an expert on radio observations of black holes for Academia Sinica Institute of Astronomy and Astrophysics. Psaltis is lead author of a new paper, published in Physical Review Letters, that details the researchers' findings. We really squeezed down the space of possible modifications," said UArizona astronomy professor Dimitrios Psaltis, who until recently was the project scientist of the Event Horizon Telescope, or EHT, collaboration. ![]() We found that whatever the correct theory is, it can't be significantly different from general relativity when it comes to black holes. "We expect a complete theory of gravity to be different from general relativity, but there are many ways one can modify it. Testing general relativity is important because the ultimate theory of the universe must encompass both gravity and quantum mechanics. Özel University of Arizona Institute for Advanced Study.Įinstein's general theory of relativity – the idea that gravity is matter warping spacetime – has withstood over 100 years of scrutiny and testing, including the newest test by University of Arizona astrophysicists from the Event Horizon Telescope collaboration.Īccording to their findings, Einstein's theory just got 500 times harder to beat.ĭespite its successes, Einstein's robust theory remains mathematically irreconcilable with quantum mechanics, the scientific understanding of the subatomic world. ![]() The bright thin ring that can be seen in blue is the edge of what we call the black hole shadow. Simulation of M87 black hole showing the motion of plasma as it swirls around the black hole. ![]()
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