gravitational waves and the general theory of relativity for reptiles

Shorter Answer
Yup. For example : if orbital energy is reducing in a Taylor-Hulse type inspiralling system, as observed and as predicted by GR, then where is it going ? If we want to keep conservation of energy then we need to reconcile that loss somewhere. In simple terms one can think of GR as a time delayed gravity theory. So a wiggle over there takes time to affect us here, the finite speed of light being the presumed cause of the delay ( c/w Newton which was instantaneous ).

Longer Answer + Quantum Digression
In generality the loss of energy from an emitter is due to 'radiative reaction'. Think of it like the recoil of an artillery piece when a round is fired. Thus your local TV station has to input energy to keep up the acceleration of the electrons ( ie. supply a force to yank them back and forth ) in it's antenna when they are chucking out photons. The idea is that you have to reconcile that locally, meaning : energy is conserved at the point & time of photon emission regardless of the ultimate fate of the photon after departure from the scene. Likewise energy is conserved at the receiver end of the deal with photon absorption, regardless of where the photon came from. In a sense we have the photon 'concept' in order to get around classical action-at-a-distance. It's the cheque in the mail.

Thus far we have the word 'graviton' to label the case of lumps of the gravitational field, in analogy to photons being lumps of the electromagnetic field. No one has been able to make that work on the theory side though ie. 'quantise gravity', unified field theory, theory of everything etc. Richard Feynman, one of the chaps who came up with Quantum Electrodynamics ( QED, the very successful quantum theory of electromagnetism ) was partly aiming to dispense with the field concept and just have objects traversing back and forth carrying the things you want to conserve. If you look at a Feynman diagram with all the straight & wiggly lines etc, then at the meeting points of the lines ( interaction vertices ) all relevant conserved quantities ( eg. energy, momentum, charge, various quantum counters ) must be accounted for by the properties of the objects involved at the vertex. The traditional wave aspect is preserved as due to the multiplicity of possible transmission paths and a probabilistic aspect to detections when large numbers of messengers are involved. Waves are a 'commentary' about groups of particles.

It's a very ancient duality/dichotomy the particle vs wave discussion, by no means settled. GR is a classical ( non-quantum ) theory and so we talk of propagating waves - entities varying continuously over large volumes of space.

There is another issue at a higher level : whereas electromagnetism involves energy ( lumps or waves ) traversing across space, gravitational disturbances are of space & time itself. A reasonable analogy is paint color varying across a canvas vs the canvas itself varying across the canvas. This comes under the rubric of 'background (in)dependence'.

Cheers, Mike.

Wonder if anyone has ever thought of this.

Hubble has imaged any number of gravitational lenses out there in the cosmos. These lens effects are essentially gravitational distortions of star light passing near massive gravitational pulls resulting in smearing of the light as it is path distorted near the field of a gravity source.

Now if gravity indeed can and does produce waves and propagates them would not these gravitational lenses be impacted by such waves and the distortions of the light be impacted to in effect cause a shimmering corresponding to the gravity wave passing?

As far as I know these images of gravitational lenses remain steady and do not exhibit any variations. Assuming we have adequate imagery of a given lens area a long term observation and time lapse recording might provide evidence of or disprove the existence of gravity waves...Observations of a number of these lens effects in various parts of the cosmos might allow one to postulate either a uniform lack of gravity waves or if images showed variations existence of them. With timing or simultaneous observations one might even be able to discern if they are uniform / simultaneous / or perhaps exhibit delays that might lead to calculations of propagation speeds. Universal assurance of a speed limit might also come out of this research..

Any intelligent comments would be appreciated.

Edward J Cox CPP

Thanks for reading my notes. Also I thank you for the reference. Reading the reference has led me to a possible line of exploration. As it is now the observations to date have focused on objects discernable and measurable via a given lens effect observation. Thus the article and the analysis of quasars and objects and the time differences caused by gravitational stretching and slowing. Hence the differences.

What would be intriguing would be to time plot lens observations in far apart lenses and in effect seek coincidence in these distant part of the sky observations. That would then perhaps lead to some other "x-factor" impacting the lens effect other than the already postulated smearing of a given lens. Discovery of coincidental time overlaps might lead one to have discovered a means of discerning gravitational waves...