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Space EU Science

New Satellite Experiment Helps Confirm Einstein's Equivalence Principle (presse.cnes.fr) 71

Part of Einstein's theory of general relativity posits that gravity equals inertial mass -- and for the first time in 10 years, there's new evidence that he's right. Slashdot reader orsayman reports: Most stories around space today seem to revolve around SpaceX, but let's not forget that space is also a place for cool physics experiments. One such experiment currently running into low orbit is the MICROSCOPE satellite launched in 2016 to test the (weak) Equivalence Principle (also knows as the universality of free fall) a central hypothesis in General Relativity.

The first results confirm the principle with a precision ten times better than previous experiments. And it's just the beginning since they hope to increase the precision by another factor of 10. If the Equivalence Principle is still verified at this precision, this could constrain or invalidate some quantum gravity theories. For those of you who are more satellite-science oriented, the satellite also features an innovative "self destruct" mechanism (meant to limit orbit pollution) based on inflatable structures described in this paper.

"The science phase of the mission began in December 2016," reports France's space agency, "and has already collected data from 1,900 orbits, the equivalent of a free fall of 85 million kilometres or half the Earth-Sun distance."
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New Satellite Experiment Helps Confirm Einstein's Equivalence Principle

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  • by AlanObject ( 3603453 ) on Sunday December 10, 2017 @01:30PM (#55711187)
    Is there any lay text around that explains how the experiment works? The article doesn't have and talks more about space pollution than relativity & gravity.
  • by SeattleLawGuy ( 4561077 ) on Sunday December 10, 2017 @01:32PM (#55711213)

    For those of you who don't pay attention to space matters, de-orbiting satellites is important because of something called the Kessler Syndrome. In effect, too much traffic up there would make it very difficult to get into space for thousands of years. This is also part of why the Chinese anti-satellite weapon test a while back was a big deal.

    We try to track everything, especially everything above a certain size, so we can prevent collissions.

    There's slightly more than a stub on Wikipedia: https://en.wikipedia.org/wiki/... [wikipedia.org]

    • Re: (Score:3, Interesting)

      by Anonymous Coward

      Said it before and I say it again. North Korea didn't need to go to the expense of building nukes. They just need to pack a few tonnes of sand around some high explosives, launch it on a rocket into retrograde orbit, and blow it up a few hundred miles high if threatened. Ain't asymmetric escalation a bitch when you're fighting the little guy with a big sting!

      • Ain't asymmetric escalation a bitch when you're fighting the little guy with a big sting!

        On the other hand, if you do have an ICBM with a nuke on it, you can do something even better than denying access to space, or even nuking a city: you can make one hell of an EMP, and charge the living shit out of the ionosphere making radio communications somewhere between difficult and impossible for days.

        We can probably clean up space debris by vaporizing it and/or slowing it down with lasers. But we have no great way to deal with an EMP, and no way to protect against one unless we can shoot down the mis

        • by Anonymous Coward

          You both show misunderstanding of the way they are thinking, probably because of both sides' propaganda.
          North Korea is not bent on bringing grief to just anyone, and (perhaps foolishly) doesn't rely on a doomsday scenario for their protection, like Soviet Union did.
          They obviously seek capability of selective attacks (pre-emptive or retributive), because these types are possible to de-escalate or to scale up or down.
          It shows that they wish to come out of it alive, if possible, so they should be let to know t

  • That they may be identical suggests they are the exact same phenomenon, which is cooler than everything else put together.

    • by HiThere ( 15173 )

      I wouldn't exactly say it's cooler, but it's something that any good theory of gravity is going to need to explain, and we need a new theory of gravity, because General Relativity doesn't play nice with quantum physics...but they both seem correct everywhere we can test either of them (usually, though, we can't test them in the same places).

      • I wouldn't exactly say it's cooler, but it's something that any good theory of gravity is going to need to explain, and we need a new theory of gravity, because General Relativity doesn't play nice with quantum physics...but they both seem correct everywhere we can test either of them (usually, though, we can't test them in the same places).

        Before a quantum gravity theory, first we need a more complete Quantum Mechanics theory

        It has been demonstrated that it is impossible to renormalize gravity in Quantum field theory (part of QM) without the use of extra dimensions. At least not without the addition of Supersymetry to QM, a theory which has been taking a bruising lately from LHC data (the simplest SUSY model has already been ruled out.)

        QFT was widely believed to be truly fundamental but largely due to the continued failures of quantizati

  • by Templer421 ( 4988421 ) on Sunday December 10, 2017 @02:42PM (#55711525)

    This is what we pay taxes for.

  • ”Most stories around space today seem to revolve around SpaceX, but let's not forget that space is also a place for cool physics experiments.”

    Well, if the sum total of your science reading amounts to scanning Slashdot headlines, perhaps this is true. But then you probably also believe that the vast majority of financial news stories involve Bitcoin.

    Otherwise... no. There’s a lot of very cool real space science going on right now! Meanwhile Musk is essentially running an innovative delivery

    • You're right, I meant "most Slashdot stories around space today seem to revolve around SpaceX". While it's of course interesting to talk about SpaceX sometimes it feels like any SpaceX launch deserves its dedicated story... That was a tentative catch-phrase because like you I believe that we have good reasons to do science in space.
  • I can't seem to find anything explaining how the test works. Is it just measuring forces on balls with different densities or something?

    • Basically yes. There is a brief description of the main instrument here [microscope.cnes.fr]. There was a mode detailed description with references to many papers but I can't find it anymore.

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