Cosmologic philosophy: general relativity proven again (Introduction)

by David Turell , Thursday, July 26, 2018, 20:28 (2099 days ago) @ David Turell

Einstein general relativity proven again.In this study a red shift is caused by gravity, not regression speed:

https://www.scientificamerican.com/article/milky-ways-black-hole-provides-long-sought-t...

"Astronomers have caught the giant black hole at our galaxy’s centre stretching the light emitted by an orbiting star—nearly three decades after they first starting tracking the star. The long-sought phenomenon, known as gravitational redshift, was predicted by Einstein’s general theory of relativity, but until now it had never been spotted in the environs of a black hole.

***

"Genzel and his colleagues have tracked the journey of this star, known as S2, since the early 1990s. Using telescopes at the European Southern Observatory in Chile, the scientists watch it as it travels in an elliptical orbit around the black hole, which lies 26,000 light-years from Earth in the constellation Sagittarius. With a mass of 4 million times the Sun, the black hole generates the strongest gravitational field in the Milky Way. That makes it an ideal place to hunt for relativistic effects.

"On 18 May this year, S2 passed as close as it ever does to the black hole. The researchers pointed instruments including GRAVITY, an instrument called an interferometer that combines light from four 8-meter telescopes and became operational in 2016. “With our measurements the door is wide open to black-hole physics,” says team member Frank Eisenhauer, an astronomer at the Max Planck institute.

"GRAVITY measured S2’s movement across the sky; at its fastest, the star whizzed along at more than 7,600 kilometres a second, or nearly 3% the speed of light. Meanwhile, a different instrument studied how fast S2 moved towards and away from Earth as it swung past the black hole. Combining the observations allowed Genzel’s team to detect the star’s gravitational redshift—its light being stretched to longer wavelengths by the black hole’s immense gravitational pull, which is consistent with the predictions of general relativity.

“'What we measured cannot be described by Newton any more,” says Odele Straub, an astrophysicist at the Paris Observatory. Future observations of S2 might confirm other Einstein predictions, such as how the spinning black hole drags space-time around with it.

“'Their data look beautiful,” says Andrea Ghez, an astronomer at the University of California, Los Angeles, who leads a competing team that uses the Keck telescopes in Hawaii to measure the star’s path around the galactic centre."

Comment: Einstein continues to be correct even as do not fully understand gravity's original particle, the graviton, if there is one.