1 00:00:01,920 --> 00:00:06,960 Speaker 1: Welcome to Brainstuff, a production of iHeart Radio. Hi brain Stuff. 2 00:00:06,960 --> 00:00:09,639 Speaker 1: I'm Lauren Bogelbaum, and today's episode is a classic from 3 00:00:09,680 --> 00:00:13,400 Speaker 1: our erstwhile host, Christian Sager. This one is about one 4 00:00:13,480 --> 00:00:16,799 Speaker 1: of the many amazing observations that researchers have made about 5 00:00:16,840 --> 00:00:19,520 Speaker 1: black holes over the past few years, and how it 6 00:00:19,600 --> 00:00:23,320 Speaker 1: proves Einstein's theory of relativity to be correct once again. 7 00:00:25,840 --> 00:00:29,280 Speaker 1: Hey brain Stuff, it's Christian Sager. Scientists always seem to 8 00:00:29,280 --> 00:00:33,960 Speaker 1: be finding new evidence of Albert Einstein being right. The 9 00:00:34,080 --> 00:00:38,800 Speaker 1: latest example comes from astronomers using the European Southern Observatories 10 00:00:39,320 --> 00:00:44,360 Speaker 1: very large telescope in Chile. Astronomers there have been studying 11 00:00:44,400 --> 00:00:48,080 Speaker 1: the stars at orbit dangerously close to the supermassive black 12 00:00:48,120 --> 00:00:51,000 Speaker 1: hole in the center of our galaxy to find that 13 00:00:51,320 --> 00:00:55,360 Speaker 1: you guessed it. Einstein's landmark theory of general relativity is 14 00:00:55,400 --> 00:00:59,360 Speaker 1: holding strong, even at the doorstep of the most extreme 15 00:00:59,440 --> 00:01:03,520 Speaker 1: gravitate sational field in our galaxy. Most galaxies are known 16 00:01:03,600 --> 00:01:08,120 Speaker 1: to have super massive black holes lurking in their cores. 17 00:01:08,160 --> 00:01:12,200 Speaker 1: In our galaxy, the Milky Way is no different. Located 18 00:01:12,280 --> 00:01:17,080 Speaker 1: approximately twenties six thousand light years from Earth, our black 19 00:01:17,120 --> 00:01:21,919 Speaker 1: hole behemoth is called Sagittarius A, and it has a 20 00:01:21,959 --> 00:01:27,400 Speaker 1: mass four million times that of our Sun. Astrophysicists are 21 00:01:27,520 --> 00:01:31,720 Speaker 1: hugely interested in black holes, as they're the most compact, 22 00:01:32,080 --> 00:01:37,640 Speaker 1: gravitationally dominant objects known in the universe, and therefore an 23 00:01:37,640 --> 00:01:42,040 Speaker 1: extreme test for relativity. By tracking the motion of stars 24 00:01:42,160 --> 00:01:46,080 Speaker 1: orbiting close to Sagittarius A, a team of German and 25 00:01:46,120 --> 00:01:51,400 Speaker 1: Czech astronomers have analyzed twenty years of observations made by 26 00:01:51,400 --> 00:01:55,440 Speaker 1: the Very Large Telescope and other telescopes using a new 27 00:01:55,480 --> 00:01:59,760 Speaker 1: technique that pinpoints the positions of these stars. One of 28 00:01:59,760 --> 00:02:05,320 Speaker 1: the stars, called S two, orbits Sagittarius A every sixteen 29 00:02:05,440 --> 00:02:09,560 Speaker 1: years and zooms very close to the black hole, around 30 00:02:09,639 --> 00:02:14,600 Speaker 1: four times the distance between Neptune and our Sun. Because 31 00:02:14,639 --> 00:02:18,920 Speaker 1: of its racetrack orbit deep inside the black hole's gravitational well, 32 00:02:19,600 --> 00:02:24,600 Speaker 1: S two is treated as a natural relativity probe into 33 00:02:24,639 --> 00:02:30,440 Speaker 1: this mysterious strong gravity environment. By precisely measuring its motion 34 00:02:30,560 --> 00:02:34,160 Speaker 1: around the black hole, the researchers could compare its orbit 35 00:02:34,360 --> 00:02:38,880 Speaker 1: with predictions laid out by classical Newtonian dynamics, and they 36 00:02:38,919 --> 00:02:43,799 Speaker 1: found that the star's actual orbit deviated from Newtonian predictions 37 00:02:43,840 --> 00:02:49,480 Speaker 1: exactly as predicted by Einstein's general relativity, although the effect 38 00:02:49,560 --> 00:02:53,400 Speaker 1: was slight. Here's a quick example of Einsteinian gravity at work. 39 00:02:53,639 --> 00:02:56,959 Speaker 1: If you have a massive object, it will bend space time, 40 00:02:57,200 --> 00:03:00,080 Speaker 1: like the famous example of the bowling ball suspended it 41 00:03:00,080 --> 00:03:03,960 Speaker 1: on a rubber sheet. If another object travels past the 42 00:03:04,040 --> 00:03:08,200 Speaker 1: massive object, the curvature of space time will deflect its 43 00:03:08,240 --> 00:03:13,000 Speaker 1: direction of motion, like a marble rolling past the bowling ball. Now, 44 00:03:13,040 --> 00:03:16,640 Speaker 1: in two thousand and eighteen, S two will swoop to 45 00:03:16,720 --> 00:03:20,640 Speaker 1: its closest point in its orbit around Sagittarius A, and 46 00:03:20,720 --> 00:03:24,919 Speaker 1: astronomers using the Very Large Telescope are preparing a new 47 00:03:25,000 --> 00:03:28,480 Speaker 1: instrument to get an even more precise view of the 48 00:03:28,560 --> 00:03:34,280 Speaker 1: extreme environment surrounding the black hole, called gravity and that's 49 00:03:34,320 --> 00:03:38,600 Speaker 1: gravity in all caps. The instrument is installed on the 50 00:03:38,720 --> 00:03:44,120 Speaker 1: Very Large Telescopes Interferometer, and astronomers not only predict that 51 00:03:44,200 --> 00:03:47,720 Speaker 1: it will get an even more precise gauge on Einstein's 52 00:03:47,760 --> 00:03:53,400 Speaker 1: general relativity, it might even detect deviations away from relativity, 53 00:03:53,800 --> 00:04:04,120 Speaker 1: possibly hinting at new physics beyond relativity. An update the 54 00:04:04,200 --> 00:04:07,920 Speaker 1: research that came out in eighteen was also groundbreaking. It 55 00:04:08,000 --> 00:04:11,080 Speaker 1: was the best evidence would record it yet, but Sagittarius. 56 00:04:11,160 --> 00:04:14,280 Speaker 1: A star is indeed a black hole and not a 57 00:04:14,360 --> 00:04:17,920 Speaker 1: different kind of phenomenon. Today's episode was written by Ian 58 00:04:17,960 --> 00:04:21,000 Speaker 1: O'Neill and produced by Dylan Fagan and Tyler Clang. For 59 00:04:21,080 --> 00:04:23,720 Speaker 1: more and listen lots of other massive topics, visit houstof 60 00:04:23,720 --> 00:04:26,599 Speaker 1: works dot com. Brain Stuff is production of iHeart Radio 61 00:04:26,920 --> 00:04:29,599 Speaker 1: or more podcasts my heart Radio visit the iHeart Radio app, 62 00:04:29,760 --> 00:04:32,520 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.