Stellar Trio Could Put Einstein's Theory of Gravity To the Test 106
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.'"
Will be interesting ... (Score:5, Interesting)
"A violation would be a complete revolution." (Score:5, 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.