J.C.MacSwell

Per Milkyway sized galaxy? Presumably? Does it happen more at certain distances/epochs?

Maybe it's time Father Ted helped us out...

I am not sure exactly of the point you are trying to make. Are you are saying that space (say, everyday Cartesian space) is not "as seen" but "as seen and calculated", or not as observed but as observed through the perspective of experience? Compare to Minkowski Spacetime, which would always, I think, be "as seen (measured) and calculated", and we don't get to experience it in everyday life in the same intuitive manner.

You see the train coming. You do not see the light coming. You only "see" it arrive.

If you feel no gravitational counteracting acceleration you are weightless in your frame of reference. If you are orbiting the Earth you are weightless. If you are in free fall you are weightless. If you are on the Moon you weigh about 1/6 what you weigh on Earth.

Fibreglass reinforced plastic, also known as glass reinforced plastic or just plain "fibreglass", can be fabricated to resist temperatures above 200 degrees F even in chemical environments. Generally a vinylester resin or isophthalic polyester resin is specified depending on use.

Sorry, I really have no idea, other than start with a google search or check at a University. Someone on here might know. It is rocket science...

Is the force accelerating the object between aphelion to perihelion one time only, or once each orbit for roughly half the orbit? So same as a thrust at all times in the current direction of the velocity...constant magnitude but varying direction. I don't know if there is an elegant solution, but a computer program that predicts orbits could have the extra terms plugged in for the force and direction and should be able to predict the new track. If the force is weak relative to that of gravity, the effect will be to decrease the orbit speed over time due to the change in path.

Back in the seventies I drove a truck that ran on gaseous propane...that was (of course) stored as LPG. It would also run on gasoline.

Fair enough, but a shell massive enough to create a time dilation...so massive enough to affect the mass measurement, at or in the shell vs at infinite or in free space further from the shell. Different potentials, so the mass is different.

Which surface? There's a gradient through the thickness of the shell. The no shell case is same as infinitely far away...higher mass (for my example lead halves have a mass of 1 kg each...regardless of history) Inside shell case is in a gravity well...lower mass (for example the half must be less than 1kg) Let me know if any of that is incorrect. I agree with the inside all being at the same potential. How is this conceptual any different from your comment to the Nobel Prize Winner, about the mass of the electron being measured at the bottom or top of the mountain, or my Kg mass of lead moved to the moon from that same thread?

Same as the inside surface. Less than the outside surface. Both less than in free space. Say you have 2 kg of lead and you divide it in half, then separate the two halves. You build the hollow sphere around one. Is it not less than 1kg? If it is still 1kg, drill a hole in the sphere and take it out and bring it to the other half. Can it now be more than 1 kg? It is still the same half.

Isn't this something you made me aware of very recently? Any matter inside is in more of a gravity well than it would be if the sphere wasn't there. The gravity may cancel out, but it is still there. It's still "bottom of the mountain", even with the resultant gravity being essentially zero.

Reading the abstract I think that is correct: The observed absence of gravitational aberration requires that “Newtonian” gravity propagate at a speed c g > 2 × 1010 c. By evaluating the gravitational effect of an accelerating mass, I show that aberration in general relativity is almost exactly canceled by velocity-dependent interactions, permitting c g = c. He seems to be saying that whereas adding any lag at all to Newtonian gravity would have it differ from observation, with GR it can match observation even as slow as the speed of light.

Except time slowing down, correct? And a mass decrease for anything inside? (compared to the same matter with no shell there)

I am not suggesting Newtonian never differs from reality or GR. I am saying Newtonian results are always consistent, regardless of what frame you choose. They give the same result. This would also be true in GR compared to the calculations from different frames in GR (not that I could do them), and, I would like to think, in reality as well. If you could somehow quickly shift the Sun to where Mercury is (or have it disappear) you would get different results in Newtonian or in GR, but in each case you would get consistent results for each, independent of choice of frame. Newtonian would instantly shift the gravitational vector to the new position of the Sun (or force would disappear). GR would do the equivalent (approximately) but only after a lag...the effect would remain in the direction toward where the Sun was going to be until after the lag. This is I think approximately right, and assuming an equivalent set of assumptions for each frames calculations. In reality the Sun shift would have to have some cause, and of course a disappearance impossible.

It doesn't happen (in reality, GR, or Newtonian) "otherwise" there would be different results in different frames

Keep in mind that using the CoM is based on a spherical distribution of mass. Other distributions won't always sum to the same thing. The gravitational vectors for Newtonian Gravity point directly to current position (no lag), and for GR they tend to the equivalent of that for lower speeds and where no abrupt changes take place, even though their is a lag in GR. For, say, two masses some distance apart stationary in the same inertial frame, the gravitational effect would be directly toward each other. It would not be any different in other frames of reference...(measurements of what is considered "current" or simultaneous aside)...otherwise the two mass system could have a net self drag effect in a frame measuring them to have velocities parallel to each other due to the lag, and of course this does not happen. Just saw MigL's post...same example

Now...you guys are going off on a tangent

The spin is not accelerating, but all points off the rotational axis are. There is a net centripetal force as the resultant of gravity and other forces. There are tidal effects as well, so the effective gravity is not constantly the same at any point.

"If you build it...they will not come back"

Thanks. Nice to know my contributions have not gone unnoticed...(and here I always thought it was you helping me)

Essentially same as Swansont except, as you can tell from my last few posts, I am not clear on how the GE is accounted for with regard to mass. If say, you took a kg of lead from Earth and dropped it off on the moon at the same temperature I would have assumed it was the same mass, 1 kg, (but say warmed up to a higher temperature, then over 1 kg, which I am sure is correct) So I'm thinking I have to do some...thinking

So without the moon changing materially, or with regard to KE, it's mass increases due to it's change in position with respect to the Earth?

Are you referring to the mass of the moon, or to the moon's contribution to the mass of the Earth/Moon System?