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beecee

Einstein's General Relativity v's the most powerful monsters of nature:

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https://phys.org/news/2019-01-student-simulates-thousands-black-holes.html

Student simulates thousands of black holes

January 9, 2019, University of Arizona:

Lia Medeiros, a doctoral student at the University of Arizona, is developing mathematical models that will allow researchers to pit Einstein's Theory of General Relativity against the most powerful monsters of nature: supermassive black holes such as Sgr A*, which lurks at the center of the Milky Way.

Medeiros has developed a diagnostic tool that astronomers can use to compare upcoming observations of supermassive black holes by the Event Horizon Telescope to the predictions of mathematical models of these maelstroms of space and time.

"We want to test whether black holes we observe in space behave the way we expect," says Medeiros, who will present her dissertation research (comprising three published papers and a fourth to be submitted to the Astrophysical Journal) in an oral session at the American Astronomical Society meeting. "If we detect a deviation from our expectations we may fundamentally change the way we think about black holes and gravity itself."

More information: "Modeling Variability and non-Kerr Spacetime Effects in Black Hole Images," Lia Medeiros, 2019 Jan. 7, 233rd meeting of the American Astronomical Society, Seattle, Washington 


Read more at: https://phys.org/news/2019-01-student-simulates-thousands-black-holes.html#jCp

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https://www.nature.com/articles/s41550-018-0449-5

The current ability to test theories of gravity with black hole shadows:

 

Abstract:

Our Galactic Centre, Sagittarius A*, is believed to harbour a supermassive black hole, as suggested by observations tracking individual orbiting stars1,2. Upcoming submillimetre very-long baseline interferometry images of Sagittarius A* carried out by the Event Horizon Telescope collaboration (EHTC)3,4 are expected to provide critical evidence for the existence of this supermassive black hole5,6. We assess our present ability to use EHTC images to determine whether they correspond to a Kerr black hole as predicted by Einstein’s theory of general relativity or to a black hole in alternative theories of gravity. To this end, we perform general-relativistic magnetohydrodynamical simulations and use general-relativistic radiative-transfer calculations to generate synthetic shadow images of a magnetized accretion flow onto a Kerr black hole. In addition, we perform these simulations and calculations for a dilaton black hole, which we take as a representative solution of an alternative theory of gravity. Adopting the very-long baseline interferometry configuration from the 2017 EHTC campaign, we find that it could be extremely difficult to distinguish between black holes from different theories of gravity, thus highlighting that great caution is needed when interpreting black hole images as tests of general relativity.

Edited by beecee

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Einstein's Relativity Theory completely changed my life. Nearly a decade later I wonder where i'd have been if I never came across those lines.

Edited by scienceafrique
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