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Space Science

Star's Black Hole Encounter Puts Einstein's Theory of Gravity To the Test (sciencemag.org) 66

Posted by BeauHD from the things-aren't-always-what-they-seem dept.
An anonymous reader quotes a report from Science Magazine: For more than 20 years, a team of astronomers has tracked a single star whipping around the supermassive black hole at the center of our galaxy at up to 25 million kilometers per hour, or 3% of the speed of light. Now, the team says the close encounter has put Albert Einstein's theory of gravity to its most rigorous test yet for massive objects, with the light from the star stretched in a way not prescribed by Newtonian gravity. In a study announced today, the team says it has detected a distinctive indicator of Einstein's general theory of relativity called "gravitational redshift," in which the star's light loses energy because of the black hole's intense gravity. The star, called S2, is unremarkable apart from a highly elliptical orbit that takes it within 20 billion kilometers, or 17 light-hours, of the Milky Way's central black hole -- closer than any other known star. A team led by Reinhard Genzel at the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, has been tracking S2 since the 1990s, first with the European Southern Observatory's (ESO's) 3.6-meter New Technology Telescope in Chile's Atacama Desert and later with ESO's Very Large Telescope (VLT), made up of four 8-meter instruments. Ghez's team at UCLA also began to observe the star around the same time with the twin 10-meter Keck telescopes in Hawaii. In a paper published today in Astronomy & Astrophysics, Genzel's group reports seeing the combined action of the relativistic effects, with the black hole's gravity redshifting S2's radial velocity by 200 kilometers per second, a small fraction of its overall speed. The results match closely with the predictions of relativity and are inconsistent with Newtonian gravity.
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Star's Black Hole Encounter Puts Einstein's Theory of Gravity To the Test More

Star's Black Hole Encounter Puts Einstein's Theory of Gravity To the Test

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  • You suck black hole

  • Must be some graviational lensing too... (Score:5, Insightful)

    by MiniMike ( 234881 ) on Friday July 27, 2018 @08:18AM (#57018402)

    Because this story also arrived here yesterday [slashdot.org]. At least this post has more info.

    • Comment removed based on user account deletion

      • Black holes do exist. Singularities however probably don't and are just an artefact of not having enough information because information can't escape a black hole.

      • I'm pretty sure that Stephen Hawking had some kind of ideas concerning the existence of black holes.

        Hopefully we get more information about black holes later this year [earthsky.org].

        It's amazing to watch the 22-year time-lapse to see the orbits of the stars, and how fast S2 goes at closest approach. It's amazing to realize that it's only moving at around 3% of the speed of light ("only"). It's amazing to consider that the gravity of the black hole itself is so strong that something moving more than 33 times as fast as

  • Amazed at the improvement of telescopes (Score:5, Interesting)

    by jfdavis668 ( 1414919 ) on Friday July 27, 2018 @08:22AM (#57018424)
    Not long ago, it was impossible to see stars at this distance. Now adaptive optics have improved the resolution so much that they are able to track stars at the center of the galaxy. This is through all the intervening dust and closer stars obstructing the view. I have trouble getting a good image of Saturn due to atmospheric turbulence, and these guys are imaging the center of the galaxy. Well done.

    • Just more evidence it's all computer-generated imagery and the earth is flat.

      "You've alreasy seen it impossibly can be done yourself!"

      This is a joke of course.

    • Re: (Score:2)

      by dissy ( 172727 )

      Now adaptive optics have improved the resolution so much that they are able to track stars at the center of the galaxy. This is through all the intervening dust and closer stars obstructing the view.

      Here is a video showing the tracked motion of the stars orbiting our central black hole, including S2
      https://www.youtube.com/watch?v=u_gggKHvfGw [youtube.com]

      It's about 20 seconds worth, but uses data spanning the 90's and early 00's, gathered from telescopes using adaptive optics.

      That data was the first time 20-ish years ago S2 was observed at the 17 light-hour distance from the black hole.
      The latest data is the second observation of its orbit at this point, but now with many more telescopes and with much more sensitive

    • It's not so much the optics as it is the software that corrects for the atmosphere.

  • Wasn't this story posted yesterday?

    • Re: (Score:1)

      by Anonymous Coward

      With gravitational lensing, you may see things twice, and even more.
      Oh well, Slashdot also experiences general relativistic effects.

  • Compare the result with other theories of gravity (Score:4, Interesting)

    by johanw ( 1001493 ) on Friday July 27, 2018 @08:33AM (#57018464)

    That Newtonian gravity is imprecise is already well known, milions of people who use GPS, Glonass or Galileo already use the general relativity calculations in practice. It is far more interesting to know how the results compare to alternative theories of gravity, like for example Verlinde's: https://en.wikipedia.org/wiki/... [wikipedia.org]

    • Re: (Score:2)

      by Jaime2 ( 824950 )

      No. This experiment was specifically designed to test General Relativity. If anyone else wants their theory tested, they should propose a testable outcome unique to their theory, then design an experiment to perform the appropriate measurements, and finally convince enough people that this experiment has enough scientific potential to secure funding.

      Meta-studies that use data gathered from other experiments are notorious for producing poor quality results. At best they should be used as a basis for securing

      • My own experience has been the opposite. When I do a test or look for data to prove/test my own ideas, no matter how hard I try I can't completely get away from confirmation bias. I suppose if I tried hard enough, I could end up with reverse confirmation bias - designing the experiment and looking at the data in a way designed to prove the opposite. That's still bias.

        When I look at results from people who were NOT trying to test my pet theory, who were collecting the data for an unrelated reason, I can bot

        • When I look at results from people who were NOT trying to test my pet theory, who were collecting the data for an unrelated reason, I can both find surprising facts I wasn't looking for and have a degree of confidence that the experiment and data weren't subconsciously (or conciously) biased

          Except now you are dredging the data and no matter what, 5% of pet theories are confirmed within a few standard deviations in such a case,

      • Oh? Someone designed an experiment that involved putting a star into an orbit around our central black hole in our galaxy? How did they do that?

  • Wtf I rtfp? (Score:4, Insightful)

    by burtosis ( 1124179 ) on Friday July 27, 2018 @08:43AM (#57018504)
    Actually it's closer to a peak of 240k/s if you look at table 3. Though the gravitational gradient must not be too large given the massive size of the black hole in question here, it would be amazing If it were possible to see a close pass stretch a star into a ribbon and watch as it is torn apart. As it is the star must deform considerably under those enormous fields.

    • Re:Wtf I rtfp? (Score:5, Interesting)

      by jfdavis668 ( 1414919 ) on Friday July 27, 2018 @09:50AM (#57018834)
      Figure 3 is showing the residual velocity, not the total velocity of the star. They have to subtract the red or blue shift caused by the star moving toward or away from us before they measure the red shift due to the light climbing out of the gravity well.
  • Not unexpected though. And more egg in the face of those in trendy circles where questioning Einstein (from a well of ignorance) has become fashionable.

    • There is nothing wrong with questioning Einstein. While his theories are highly successful, they are not the end of physics.

      What's more, questioning conventional wisdom helps understand it.

      • Re: (Score:2)

        by meglon ( 1001833 )
        He might be referring to the few dipshits around who simply come out and say Einstein, and GR, are outright wrong.... not because of something that's shown evidence of that (because nothing has), but because they're peddling their own incredible stupid con game to leech money out of other ignorant idiots.

        That said, science is always questioning, but to promote an idea it needs to at least have some validity (observational, experimentally, or inferred). I've no doubt that in the next several hundred years

        • Quite.

          There is a difference between questioning something, and making a claim about something.
          Maybe just a poor choice of words by OneHundredAndTen.
          It happens.

    • Comment removed based on user account deletion

    • What trendy circles are you referring to? Quantum mechanics? :)

      I'm more curious if there was a planet orbiting this star is the star close enough that time would be dilated by the movement and proximity to the black hole.

  • What's really cool is that this star passes about as close to a black hole as the Voyager probes are from Earth right now. Can you imaging what it would look like if it were that close to our own solar system? What effect would its mass have on our solar system?
    https://voyager.jpl.nasa.gov/m... [nasa.gov]

  • S2 [wikipedia.org] has about 14 solar masses, but it passes relatively close to the galaxy's central black hole (about 4x the distance from our sun to Neptune). Its orbital period is just 16 years despite having a semi-major axis about 970x that of the Earth (about 32x bigger than Neptune's orbit). The Max-Planck Institute for Extraterrestrial Physics [mpe.mpg.de] put together an animation of the previous decade of observations (1992-2013). You can see how it whips around the black hole [youtube.com] at closest approach.

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