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Stellar Trio Could Put Einstein's Theory of Gravity To the Test 106

Posted by samzenpus
from the there's-a-first-time-for-everything dept.
sciencehabit writes "In a cosmic coup, astronomers have found a celestial beacon known as a pulsar in orbit with not one, but two other stars. The first-of-its-kind trio could soon be used to put Einstein's theory of gravity, or general relativity, to an unprecedented test. 'It's a wonderful laboratory that nature has given us,' says Paulo Freire, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany, who was not involved in the work. 'It's almost made to order.'"
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Stellar Trio Could Put Einstein's Theory of Gravity To the Test

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  • by TrollstonButterbeans (2914995) on Monday January 06, 2014 @12:43AM (#45875801)
    n-body calculations are hard enough with Newtonian physics. The "Einsteinian physics" calculations must be a bit maddening, but at least they have found a star system to test it out.
    • by Nemyst (1383049)
      I can't even begin to imagine the mathematics required, but I'm fairly sure that when you start talking about general relativity you need to drop Euclidean space. Then you can enjoy tensors. And geodesics (ie. the path that a free-moving object would follow, which no longer is necessarily a line). And so much more stuff I've forgotten and have no wish to remember.

      I still have nightmares from my Electromagnetism III class.
    • by jabuzz (182671)

      n-body calculations where n>3 are all simulations. Anyone coming up with a mathematical solution to such a system is in line for a Nobel prize.

      The trick is to remember there are no real three body systems in the entire universe...

      • n-body calculations where n>3 are all simulations.

        I was going to say, I can solve plenty of N-body calculations where N = zero.

        (I think anyway. I'm a biologist not a mathologist. Maybe N = zero is a real thing that isn't simply "zero." If so, I sincerely apologize and accept my punishment.)

  • The summary is light on any details, so here:

    The distinctive new system opens the way for testing a concept behind general relativity known as the equivalence principle, which relates two different conceptions of mass. An object's inertial mass quantifies how it resists pushing or pulling: It's easier to start a stroller rolling than a car because the stroller has less inertial mass. A thing's gravitational mass determines how much a gravitational field pulls on it: A barbell is heavier than a feather because it has more gravitational mass.

    The simplest version of the equivalence principle says inertial mass and gravitational mass are equal. It explains why ordinary objects like baseballs and bricks fall to Earth at the same rate regardless of their mass—as legend claims Galileo showed by dropping heavier and lighter balls from the Leaning Tower of Pisa.

    The strong equivalence principle takes things an important step further. According to Einstein's famous equation, E = mc2, energy equals mass. So an object or system's mass can be generated by the energy in the gravitational fields within the system itself. The strong equivalence principle states that even if one includes mass generated through such "self-gravitation," gravitational and inertial mass are still equal. ...
    By tracking the system's evolution, Ransom and colleagues should be able to tell whether either the inner white dwarf or the pulsar falls faster toward the outer white dwarf and test strong equivalence about 100 times as precisely as before, Damour says.

    "Gravitational Field"... space-time curvature "field"? Uhm, "gravitational mass" vs "inertial mass" equivalence... "explains why" o_O? Shh! The astrophysicists are over. Don't mention the Higgs!

    In all seriousness, we know damn well Einstein's equations are simply better approximations / explanations than Newton's approximations are -- It's only a matter of time before we prove them "wrong" (but still damn good and useful approximations, like Newton's) -- We just need some elusive experimental evidence to prove it, and this could be it due to the large gravitational coefficients and a steady measurement scale provided in the pulsar. That is, unless Einstein's approximation turns out to be more accurate than our observations of this system. It shouldn't be any more of a "revolution", as TFA states, if the observations prove to be in violation of the equations: We should be trying to find better equations anyway thanks to that whole Standard Model thing, and we are. Physics seems to goes through these periods where a bunch of new theories explain various things to a precision, the precision is surpassed in observations, and then someone like Newton, Einstein, Feynman, Hawking, etc. comes along and presents elegant / unifying equations to explain the disparate pieces better. Looks like we're still in the middle of the very important prove old-theories "wrong" (read: inaccurate, conflicting with some observations) and scratch our head over tests for new hypotheses to fit more accurate measurements stage.

    • In all seriousness, I know nothing of this. You seem like maybe you have a handle on it, and that's great. What I have to ask is, what in the hell is vortexcortex.com?
    • by dcollins (135727) on Monday January 06, 2014 @02:19AM (#45876099) Homepage

      Yeah, that sort of sounds like a bunch of late-night-I've-got-the-munchies BS.

      FTA: "Paulo Freire, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany... says a violation would be 'a complete revolution.'"

      No offense, but I'm going to trust the astronomer at the world-renowned scientific institute over the indie-game artist on this one.

      • VortexCortex wasn't appealing to his authority though. He provided reasoning beyond "listen to me, I know what I'm talking about."

        I'd have to read TFA (shudder) to see if the astronomer backed up his statement, but an astronomer simply saying "This is revolutionary!" would be less convincing than what VortexCortex posted if that's all there was.
    • by Nemyst (1383049)
      It would be a revolution in the sense that it would be, as far as I know, the first time general relativity is shown wrong factually. This is different from the quantum mechanics/relativity problem, which is that the two are not compatible (so we know something's missing, but we don't know where).
    • by Guy Harris (3803)

      That is, unless Einstein's approximation turns out to be more accurate than our observations of this system.

      Err, umm, "accurate", when it comes to predictions of scientific theories, means "closely matches the observations", so a theory can only be "more accurate than our observations of this system" if the observations in question are wrong and subsequent observations, determined to be (more) correct, are better matched by the predictions of the theory. Is that what you mean here?

    • Wait just a nanosecond. I'm just a self educated layman, but didn't Einstein come up with an explanation for how gravity works (mass distorts space-time)? Whereas Newton believed gravity worked because...what? Einstein did a lot more than just come up with a better equation didn't he? Heck, even the concept of space-time is very important concept, that, while illustrated through equations, took us far beyond the Newtonian understanding of the Cosmos. It's much more than just refining the math. Don't y

    • Actually, AFAIK we don't know that Einstein's equations are wrong at all. That's a surmise. (Yes, there's something wrong somewhere, but it may not be GR.) It may well be true, and we won't know until we find discrepancies. That's what this astronomical research is for. Without discrepancies, about all we can say is that GR accounts for the observed facts and is mathematically elegant, and looking for new equations is speculative at best.

  • Delicious (Score:5, Funny)

    by jones_supa (887896) on Monday January 06, 2014 @01:40AM (#45876003)

    In a cosmic coup, astronomers have found a celestial beacon

    Mmm...cosmic soup with bacon!

  • Ok, help my layman ass out here. IIRC, according to Einstein, acceleration and gravity aren't just similar phenomena, but are the exact same phenomena, and, since you are always travelling at c through the combined spacetime continuum, which gravity warps, the gravitational pull is you actually accelerating through this warped spacetime.

    That seems way too freaking cool to fail at some umpteenth decimal.

    • by Anonymous Coward

      ... since you are always travelling at c ...

      Light travels at c in a vacuum and anything with mass does not. Be wary of anyone who tells you otherwise.

      (I'm a physicist)

    • by hutsell (1228828)

      Ok, help my layman ass out here. IIRC, according to Einstein, acceleration and gravity aren't just similar phenomena, but are the exact same phenomena, and, since you are always travelling at c through the combined spacetime continuum, which gravity warps, the gravitational pull is you actually accelerating through this warped spacetime.

      That seems way too freaking cool to fail at some umpteenth decimal.

      I've always found the feeling associated with thinking about the Principle of Equivalence to be exquisite — wistfully thinking something beautiful would be lost if (or when) it was disproven.

  • Whose to say it wasn't? Maybe some advanced civilisation built it to test just this principal. Maybe we are simply looking over the shoulder of someone else's work. How do they correctly reference that in the eventual paper? :-)

    Bob.

  • The article suggests that E=MC^2 does not solely mean antimatter and matter collide and tada you get energy or that a hadron collide can convert energy into matter. They claim that mass that is moving contains energy and thus generates more mass/gravity. I certainly don't remember learning THAT in school. I know if you're heavy and moving fast, more time will occur throughout the mass but they didn't say gravity would increase. Then they refer to "self gravitation" as in the object pulling in on itself a
    • by bunratty (545641)
      The equation e=mc^2 means that matter and energy are the same thing, just in different forms. When you move, you gain kinetic energy and therefore gain in mass and therefore exert more gravity on other bodies. The equation just gives a way of converting units of mass to units of energy. It's just like converting nanometers to kilometers -- both units represent the same kind of quantity (length), just different amounts.
  • "Made to order?" Hmm, so the creationists are right after all. There is a creator and he clearly likes science...

    Could have been worse I guess.

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