<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>[Curiosity]: This graviton imbalance could be thought of as a "field" whose strength could be measured by counting the number of gravitons moving toward the Earth from all possible directs, and the number of gravitons moving away from the Earth toward all possible directions.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
This is a good question. The gravitons that actually hit the Moon are the same ones that would have hit it if Earth were absent. The Moon gets pushed because some of the gravitons that would have hit the Moon and balanced the forces from all directions are absent, being blocked by Earth. So there is a net push in the direction of the missing gravitons.
This pushing mechanism can always be thought of as a pulling mechanism by focusing on just the missing gravitons responsible for the net force. We can consider a missing graviton as a "negative mass" graviton flying from Earth to Moon that produces a pull, instead of what it really is, a positive mass graviton producing a push on the Moon's opposite side. Negative-mass, pulling gravitons are simply a means to think about gravity in the more traditional way. Many people find this less confusing. This analogy is fully equivalent to the real "pushing" situation.
<BLOCKQUOTE id=quote><font size=2 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>gravity doesn't have to "travel" from the Earth to the Moon, or the Earth to the Sun, or any where else for these resulting forces to act in instantaneous, real time. The graviton imbalance fields exist in the space surround the masses all the time. Each mass just reacts to the graviton imbalance properties of field of the other mass's field that it happens to be moving through.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
The negative-mass, pulling gravitons do have to travel from Earth to Moon. It is true that the Earth's gravity field is "static" in the sense of a flowing waterfall that appears the same whenever we look. But in reality, each drop of water (or negative graviton) is continually being replaced by another from behind. So the field is really "steady state" and continually regenerated, not "static", where the latter would imply no moving parts.
Either way, using pushing or pulling gravitons, the gravitons travel on a straight line from Earth to Moon. However, purely because the Moon has forward motion, the direction of the applied force is at an angle. This would be obvious if we imagined the Moon as moving forward at the same speed as the gravitons approaching from Earth. Then from the Moon's perspective, the gravitons would be approaching at a 45-degree angle to Earth's direction. Or if the Moon traveled much faster than the gravitons, they would mostly hit the Moon's leading face and pull forward. In all cases, they tend to increase the Moon's speed.
The absence of such an observed effect sets a lower limit to the speed of the gravitons. Five other experiments do the same thing. So we know the speed of gravity is very much greater than the speed of light. The measured lower limit is now 20 billion c. In <i>Pushing Gravity</i>, other properties of gravitons are also worked out, and these reenforce the need for a very high speed. If gravitons were not very fast, they would not deposit enough momentum to give a force as strong as gravity unless they were more massive. But if they were more massive, they would heat up the bodies they strike to the point where they melt and vaporize.
For all the above reasons, the speed of gravity must be >> the speed of light. -|Tom|-
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