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

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.'"

8 of 106 comments (clear)

  1. Re:If only /. beta was tested as much as Einstein by Virtucon · · Score: 4, Insightful

    Isn't that the point of a Beta release? To obtain feedback and to fix what isn't right with something?

    --
    Harrison's Postulate - "For every action there is an equal and opposite criticism"
  2. Will be interesting ... by TrollstonButterbeans · · Score: 4, Interesting

    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.

    --
    Priest: "Universe from nothing, no laws of physics, sped up time"+ huge discrepancies. Creationism? No. Big Bang Theory
    1. Re:Will be interesting ... by Anonymous Coward · · Score: 4, Insightful

      Meh, just simulate it. No need to solve the equations, and simulating it isn't very hard. We have computers now, they are good at this.

      But how do you know if your simulation is correct?

      Anyone could easily write a sim that has three stars and they all coexist, happily passing through each other or something ridiculous. The point here is that we can see if the Theory and any simulations match the real world.

    2. Re:Will be interesting ... by dotancohen · · Score: 4, Insightful

      It's just a bloody simple system of differential equations. n bodies, each has a location (3 coordinates) and a speed vector (3 coordinates), so you have six equations. The speed is obviously the derivative of the location, and the theory gives you the equation to calculate the derivative of the speed. Look up Fehlberg or "Adaptive Runge-Kutta-Fehlberg" and you are there.

      That's Newton.

      With relativity things get hard, quick. Both time (thus, speed) and space (thus, speed and distance) dilate, mass changes (thus, the attractive forces between bodies and thus their acceleration, and thus their speed, and thus their location), and some other oddities.

      --
      It is dangerous to be right when the government is wrong.
  3. "A violation would be a complete revolution." by VortexCortex · · Score: 4, Interesting

    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.

    1. Re:"A violation would be a complete revolution." by dcollins · · Score: 5, Insightful

      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.

      --
      We know where leadership by an anti-intellectual "strongman" who scapegoats minorities and likes boisterous rallies goes
  4. Delicious by jones_supa · · Score: 4, Funny

    In a cosmic coup, astronomers have found a celestial beacon

    Mmm...cosmic soup with bacon!

  5. Re:Happy Sunday from The Golden Girls! by Anonymous Coward · · Score: 5, Funny

    Your heart is true, you're a pal and a cosmonaut.

    God dammit I keep seeing this posted here over and over with the same error every time. Every time!

    It's "you're a GAL" you dipshits!