[Vision2020] Newtonian Gravity Replaced by Space/Time Geometry

Tbertruss at aol.com Tbertruss at aol.com
Sat May 7 16:07:46 PDT 2005

Donovan wrote:

"In science the Theory of Gravity is still
just a theory."  

Gravity in Relativity no longer exists as it is described in Newtonian 
Physics.  It has been replaced by mass altering the geometry of space/time.  Objects 
near a mass (our Sun, for example) follow the geometry of space/time (Earth's 
orbit follows this geometry) that the mass creates, but are not acted upon by 
a force (gravity) at a distance, which is the intuitive notion that we often 
think of to imagine gravity keeping the Earth in orbit around our Sun.

Nonetheless, the Newtonian equations dealing with gravity, speed, mass and 
force are perfectly workable to launch satellites into orbit above Earth.  I 
doubt anyone at NASA uses Relativity to do the math to successfully launch a 
satellite into a required orbit, though I have not verified this.  Newtonian 
physics does the job just fine.

Though I disagree with you that the theory of gravity is "just a theory," 
given that its predictions have been empirically validated over and over given 
certain limitations, it is a good example of a scientific theory which has been 
replaced by a more accurate theory (Relativity) to predict the behavior of 
matter in those cases where it is required.


This below is from the link above:

How spacetime curvature simulates gravitational force

The curvature of spacetime considered as a whole implies a rather complex 
picture that is usually treated with the tools of differential geometry and that 
requires the use of tensor calculus. It is possible though to understand - at 
least approximately - the mechanism of gravitation without tensors when the 
total curvature of spacetime is split into two components:

curvature of space 
time dilation. 

The above components of the curvature of spacetime, and only these, are 
responsible for the gravitation according to Einstein's theory.The effect of the 
first component, the curvature of space, is negligible in all cases when the 
velocities of objects are much smaller than the speed of light and when the 
ratios of masses divided by the distances separating their centers of mass are much 
smaller than a specific constant, namely the ratio of speed of light squared 
to Newtonian gravitational constant: . So for the majority of cases in the 
universe, and certainly for almost all cases in our solar system except 
precession of perihelion of Mercury and deflection of light rays in the vicinity of the 
Sun, we may treat the space as flat, as ordinary Euclidean space. It leaves 
us only with the gravitational time dilation as a possible reason for the 
illusion of "gravitational force" acting at the distance. Assuming that the ratio 
of masses to distances between them are smaller than the constant above, the 
time dilation is tiny, but it is enough to cause "Newtonian gravitational 
attractive force" as we know it.The reason for this illusion is this: any mass in 
the universe modifies the rate of time in its vicinity this way that time runs 
slower closer to the mass and the change of time rate is controlled by an 
equation having exactly the same form as the equation that Newton discovered as his 
"Law of Universal Gravitation". The difference between them is in essence not 
in form since the Newtonian potential is replaced by the Einsteinian time 
rate dt / dt, where t is the time at a point at vicinity of the mass (the proper 
time of objects at this point in space, the time that is measured by the 
clocks in this point) and t is the time at observer at infinity, with the right 
side of the equation  staying the same as in Newtonian equation (with accuracy to 
irrelevant constants). Because of the same form of both equations, the path 
of the object that takes an extremum of proper time while traveling, and by 
this taking a geodesic in spacetime, is the same (with accuracy to the negligible 
in this case curvature of space) as the Newtonian orbit of this object around 
the mass. So it looks as if the path of the object were bent by some "force 
of attraction" between the object and the mass. Since bending of the object's 
path is clearly visible and the time dilation extremely difficult to notice, a 
(fictitious) "gravitational force" has been assumed rather than a (real, 
presently measured with precise enough and formerly unavailable clocks) time 
dilation as the reason for bending the paths of objects moving in vicinity of 
masses.So without any force involved into keeping the traveling object in line the 
object follows the Newtonian orbit in space just by following a geodesic in 
spacetime. This is Einstein's explanation why without any "gravitational forces" 
all the objects follow Newtonian orbits and at the same time why the Newtonian 
gravitation is the approximation of the Einsteinian gravitation.In this way 
the Newton's "Law of Universal Gravitation" that looked to people who tried to 
interpret it as an equation describing a hypothetical "force of gravitational 
attraction" acting at a distance (except to Newton himself who didn't believe 
that "action at a distance" is possible) turned out to be really an equation 
describing spacetime geodesics in Euclidean space. We may say that Newton 
discovered the geodesic motion in spacetime and Einstein, by applying Riemannian 
geometry to it, extended it to the curved spacetime, disclosed the hidden 
Newtonian physics, and made its math accurate.
V2020 post by Ted Moffett

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