[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  It has been replaced by mass altering the geometry of space/time.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certain limitations, it is a good example of a scientific theory which has been
replaced by a more accurate theory (Relativity) to predict the behavior of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.

http://en.wikipedia.org/wiki/Gravity

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.
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V2020 post by Ted Moffett

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