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Posted by pmb on February 14, 2000 16:20:18 UTC

: Decompression of the same is bound to create ANTI GRAVITATIONAL FORCES. : As simple as that.. : Any Debates on this is welcome...

That's true. Decrease pressure - Less pressure/less gravity. But I'm not sure that is how you meant it. In normal situations - less pressure - less gravity but simply a decrease in the magnitude.

However that siad. Pressure (stress) is a source of gravity too along with mass-energy and momentum.

Suppose you have an infinite sheet of mass in the z=0 plane, which I'll call it a "normal wall" (i.e. a really big wall). Picture this as a ciurcular disk for reason of illustration). There will be stresses (i.e. pressure) in the radial direction directed toward the center of the wall which contribute to the gravitational force (or acceleration if you prefer that language).

On the other hand - If you have a wall in which the pressure was directed in the opposite direction i.e. radially outward (repulsive) as it was in the normal wall then the pressure will contribute in the oppostite way than a normal wall. In some circumstances it can be that the wall will cause objects to accelerate away from it.

In other cases there can be no gravitational force and yet the source can alter the space around it causing it to be non-Euclidean (and yet the spacetime can still be flat!!!)

Actually Alan Guth's theory of inflation is all about gravitational repulsion.

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