WEBVTT - BrainStuff Classics: How Can a Black Hole Help Prove General Relativity?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeart Radio. Hi brain Stuff.

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<v Speaker 1>I'm Lauren Bogelbaum, and today's episode is a classic from

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<v Speaker 1>our erstwhile host, Christian Sager. This one is about one

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<v Speaker 1>of the many amazing observations that researchers have made about

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<v Speaker 1>black holes over the past few years, and how it

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<v Speaker 1>proves Einstein's theory of relativity to be correct once again.

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<v Speaker 1>Hey brain Stuff, it's Christian Sager. Scientists always seem to

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<v Speaker 1>be finding new evidence of Albert Einstein being right. The

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<v Speaker 1>latest example comes from astronomers using the European Southern Observatories

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<v Speaker 1>very large telescope in Chile. Astronomers there have been studying

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<v Speaker 1>the stars at orbit dangerously close to the supermassive black

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<v Speaker 1>hole in the center of our galaxy to find that

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<v Speaker 1>you guessed it. Einstein's landmark theory of general relativity is

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<v Speaker 1>holding strong, even at the doorstep of the most extreme

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<v Speaker 1>gravitate sational field in our galaxy. Most galaxies are known

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<v Speaker 1>to have super massive black holes lurking in their cores.

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<v Speaker 1>In our galaxy, the Milky Way is no different. Located

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<v Speaker 1>approximately twenties six thousand light years from Earth, our black

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<v Speaker 1>hole behemoth is called Sagittarius A, and it has a

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<v Speaker 1>mass four million times that of our Sun. Astrophysicists are

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<v Speaker 1>hugely interested in black holes, as they're the most compact,

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<v Speaker 1>gravitationally dominant objects known in the universe, and therefore an

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<v Speaker 1>extreme test for relativity. By tracking the motion of stars

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<v Speaker 1>orbiting close to Sagittarius A, a team of German and

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<v Speaker 1>Czech astronomers have analyzed twenty years of observations made by

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<v Speaker 1>the Very Large Telescope and other telescopes using a new

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<v Speaker 1>technique that pinpoints the positions of these stars. One of

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<v Speaker 1>the stars, called S two, orbits Sagittarius A every sixteen

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<v Speaker 1>years and zooms very close to the black hole, around

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<v Speaker 1>four times the distance between Neptune and our Sun. Because

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<v Speaker 1>of its racetrack orbit deep inside the black hole's gravitational well,

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<v Speaker 1>S two is treated as a natural relativity probe into

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<v Speaker 1>this mysterious strong gravity environment. By precisely measuring its motion

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<v Speaker 1>around the black hole, the researchers could compare its orbit

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<v Speaker 1>with predictions laid out by classical Newtonian dynamics, and they

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<v Speaker 1>found that the star's actual orbit deviated from Newtonian predictions

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<v Speaker 1>exactly as predicted by Einstein's general relativity, although the effect

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<v Speaker 1>was slight. Here's a quick example of Einsteinian gravity at work.

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<v Speaker 1>If you have a massive object, it will bend space time,

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<v Speaker 1>like the famous example of the bowling ball suspended it

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<v Speaker 1>on a rubber sheet. If another object travels past the

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<v Speaker 1>massive object, the curvature of space time will deflect its

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<v Speaker 1>direction of motion, like a marble rolling past the bowling ball. Now,

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<v Speaker 1>in two thousand and eighteen, S two will swoop to

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<v Speaker 1>its closest point in its orbit around Sagittarius A, and

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<v Speaker 1>astronomers using the Very Large Telescope are preparing a new

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<v Speaker 1>instrument to get an even more precise view of the

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<v Speaker 1>extreme environment surrounding the black hole, called gravity and that's

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<v Speaker 1>gravity in all caps. The instrument is installed on the

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<v Speaker 1>Very Large Telescopes Interferometer, and astronomers not only predict that

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<v Speaker 1>it will get an even more precise gauge on Einstein's

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<v Speaker 1>general relativity, it might even detect deviations away from relativity,

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<v Speaker 1>possibly hinting at new physics beyond relativity. An update the

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<v Speaker 1>research that came out in eighteen was also groundbreaking. It

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<v Speaker 1>was the best evidence would record it yet, but Sagittarius.

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<v Speaker 1>A star is indeed a black hole and not a

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<v Speaker 1>different kind of phenomenon. Today's episode was written by Ian

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<v Speaker 1>O'Neill and produced by Dylan Fagan and Tyler Clang. For

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<v Speaker 1>more and listen lots of other massive topics, visit houstof

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<v Speaker 1>works dot com. Brain Stuff is production of iHeart Radio

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<v Speaker 1>or more podcasts my heart Radio visit the iHeart Radio app,

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