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Grahamshortuk
2010-Jun-05, 01:23 AM
A black hole, we believe is a gravity gradient which probably spins spacetime and is so steep past the event horizon that no amount of force can overcome it's gravitational pull.
White holes can only exist in mathematics so long as they have no mass nor energy absorbed. The oppositeof a black hole.
So what if one way a White hole was to exist in reality was to have the opposite gravity gradient of a black hole? Visualise your rubber sheet distended downwards infinitely to a sharp point singularity by the black hole: now flip it over so the gradient points up and has the opposite effect on appraching matter and energy. The White hole gravity gradient, preventing anything landing on it by virtue of an impossibly steep gravity gradient.

Just an idea I had. What does anybody think of this?

cjameshuff
2010-Jun-05, 02:03 AM
IIRC, while the curvature of spacetime around a white hole is opposite to that around a black hole, the gravitational behavior remains identical. Lengths and time are distorted the same way, geodesics are the same, masses still accelerate toward the more highly curved spacetime. Matter will fall into a "white hole" just as it falls into a black hole, and despite the name, light will not be able to escape.

The common explanation of objects rolling "downhill" into the dip in the rubber sheet is a misleading, flawed version of the rubber sheet analogy. All it does is attempt to explain gravity by assuming gravity.

Instead, think of a pair of wheels rolling along that rubber sheet, linked by a fixed axle so when one makes one rotation, the other does as well. Each wheel travels the same distance along the rubber sheet beneath it, and on a flat sheet, they always travel in a straight line as seen from above. However, when they pass by that peak or dip in the rubber, the wheel that's closer to the dip would have further to roll than the other, because the sheet on that side is more stretched. Rolling along the rubber, the wheels would thus turn toward the peak or dip, regardless of whether the rubber is stretched "up" or "down".

Grahamshortuk
2010-Jun-05, 12:57 PM
I think the analogy I was try to draw, unsuccessfully, was that a flat sheet represents the "normal" uncurved spacetime with no mass objects in it. A depression "downwards" in this represents a curviture towards an area of stretched or rarified spacetime. Bearing this in mind, try now to see that a peak in our representation is a region of spacetime that is compressed and has the effect of being creating a gradient towards a lower density which is the normal density, thus making it difficult for anything to approach this region. If such a thing as AntiGravitrons were possible, which I know they are not, then they have this affect on the fabric of spacetime.