Posted on 09/05/2002 9:08:22 AM PDT by RightWhale
You could have stopped after two words.
Although Bill might disagree.
er - what was the topic of the thread again?
Shalom.
Physicist has some good things to add on this thread...
They better use my name.
I once thought so too, but Physicist explained to me that light's apparent mass (from its energy content) has real gravity. Yes, a photon has a zero rest mass, but it's never at rest.
Letter to the National Lampoon back in the 70's:
Dear Sirs:
If I'm so smart, how come I'm dead?
Sinerely,
Albert Einstein
Well like I said above I'm no gen-rel geek but I do believe one should, rather, discuss the speed of gravitational waves. LIGO's site (Laser Interferometer Gravitational-Wave Observatory) has a discussion about it--
"Gravitational waves are ripples in the fabric of space and time produced by violent events in the distant universe, for example by the collision of two black holes or by the cores of supernova explosions. Gravitational waves are emitted by accelerating masses much as electromagnetic waves are produced by accelerating charges. These ripples in the space-time fabric travel to Earth, bringing with them information about their violent origins and about the nature of gravity."
Well that was actually kind of lame. Lemme see if I can find anything better-- here's something written in '99--
"According to Newton's theory of gravitation, the binary period of two point masses (e.g., two stars) moving in a bound orbit is strictly a constant quantity. However, Einstein's general theory of relativity predicts that two stars revolving around each other in a bound orbit suffer accelerations, and, as a result, gravitational radiation is generated. Gravitational waves carry energy and momentum at the expense of the orbital decay of two stars, thereby causing the stars to gradually spiral towards each other and giving rise to shorter and shorter periods. This anticipated decrease in the orbital period of a binary pulsar was first observed in PSR 1913+16 by Taylor and Weisberg. The observation supported the idea of gravitational radiation first propounded in 1916 by Einstein... [who] showed that the first order contribution to the gravitational radiation must be quadrupolar in a particular coordinate system..."
The "quadrupole moment tensor of the energy density of the source", which is gotten to after you fix and gauge and pick a coordinate system and solve for Einstein's (linearized) equations Dal(h'_mu*nu) = -16PiGT^mu*nu (h' = trace-reversed perturbation, G = Einstein tensor, and I don't know what the hell T is... Tensor shorthand for something...) and fool around with a Fourier transform and take out the spatial part, is given on page 10 and has too many super/subscripts for me to put it here easily...
Photons only have percieved mass due to their speed. At rest, they would weigh nothing. Light has no mass, right?!
Likewise, gravitons have more mass than photons because gravitons travel CONSIDERABLY faster than photons.
Ergo, gravity is considerably faster than light.
You heard it here, first.
Oh, don't kid yourself. RightWhale had already considered that calculation, he was just too lazy to do the complex contravailing-factor mathematics involved.
Whaddya mean by that, you ask?
WELL, as is well known, Hillary! is a powerful locus of "dark energy", and therefore exerts a none-too-slight and all-too-perceptible repulsion amongst all right-thinking Life Forms -- thus contravailing the massive gravitational pull of the accumulated filth on Old Crusty.
Ergo, one has to divide the mass of right-thinking Life Forms present in the Empire State Building by the total mass thereof, etc., etc... the math ends up being mindbendingly annoying!! (which is another caused effect which has a powerful statistical correlation with Hillary! in all repeatable studies)
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