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-   -   Brane Movement Causing Gravity (http://www.physicsforums.com/showthread.php?t=100779)

 -Job- Nov20-05 12:40 PM

Brane Movement Causing Gravity

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In trying to fathom why matter would curve space-time, i realized a moving brane may offer a neat model of this. I made a drawing depicting how this would work which i think is better than i can explain in words. Don't take this too seriously, if you don't think it works just point out what you think is wrong and i'll move on to better things, there's no need for yelling or insulting, i'm not a stubborn person and i'll probably agree with you fast enough.
http://www.bloo.us/branegrav.gif

 -Job- Nov21-05 08:19 PM

Well, if you ask me i see at least one unlikely thing in this model which is that it implies that in the universe there are regions where matter would be accelerated for what would appear to be no good reason. For example, at the top and bottom sides of the brane matter would just be accelerated at maximum gravity without the need for having any matter around to bend space. :smile:

 gtimespace May15-08 07:21 PM

Accelerated Brane

I don't think a brane which has constant velocity could be stretched by an inertial mass for very long. The mass landing upon it would eventually attain the same velocity as the brane and, I must assume a stretched brane would eventually return to it's un-stretched original shape and the mass would then fly off at about 2 times the brane velocity. Even if the indentation remained, is there any reason for anything else to fall into it?

If on the other hand, the brane were to be accelerated at a constant rate then anything it came into contact with would be accelerated towards it and the surface of the brane could remain indented and follow the moving particles, strings, whatever on it's surface as long as the acceleration continued. I hesitate to offer any theories about what could have caused this acceleration, but it could be simulated equivalently by a flat flexible sheet perpendicular to a gravitational field, such as the one on the surface of the earth, indented by spheres resting or rolling on it. I think this is more akin to the warping of spacetime by gravity. I found a good description of the warping of spacetime by gravity in Brian Greene's "The Fabric of the Cosmos."

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