Re: Gravitational Confusion
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Posted by ronron on December 07, 19100 at 12:41:18:
In Reply to: Gravitational Confusion posted by Brian on November 27, 19100 at 09:35:00:
brian, i didn't see a response to your original question about
whether gravity can be simulated. so yes, it can. this is the
equivalence principle that states that you cannot determine
whether you are experiencing an increase in a gravitational field
or an acceleration from within that frame. the usual example given
is an elevator going up. you feel the force on your feet,
but the equivalence principle states that you could just
as well be experiencing an increase in the gravitational field
instead of the elevator's acceleration. short version, the equivalence principle asserts the indistinguishability
between an acceleration and a change in gravitational field. re gravity and the curvature of spacetime, you start with
flat 4 dimensional spacetime in the absence of mass. mass
deforms the spactime (like a marble placed on a loose drum
or something. then other objects traversing "straight" lines
are compelled to follow the geometry created by the marble.
this is the idea of a geodesic in GR, the attempt to
follow the straightest line possible. this is basically the
idea in GR - gravity is pretty much following the path you
started on. when the path curves, you curve. the higher
the curvature of spacetime (determined by mass), the
greater your own curvature as you travel. as Misner, Thorne and Wheeler say, "mass tells geometry
how to curve, and geometry tells mass how to move."
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