# Analog models of gravity

## Main Question or Discussion Point

In analog models of gravity, such as http://en.wikipedia.org/wiki/Acoustic_metric" [Broken], the motion of "matter" is influenced by the metric. Detection of Hawking radiation in sonic black holes is a goal that some experimental groups are working on. However, in GR geometry and matter act on each other. Are there analog models of gravity in which the metric is also shaped by "matter" via the Einstein field equation?

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But Hawking radiation is derived from quantum field theory on a fixed spacetime, isn't it?

I think there are analogue models in which at least some components of the metric are shaped by matter, but there are none in which the equation for the metric has the form of the Einstein equations (except for AdS/CFT)

http://arxiv.org/abs/0909.3834

As long as you aren't going into graviton theory, gravity is best described on a 2d plane and like an elastic sheet of material, as heavy objects (greater mass) sink deeper than those which are lighter, similar to gravity each object is affected differently by mass and density.
as an object sinks deeper the gradient of the walls of the material becomes greater than 1, this represents its gravitational attraction.
A spherical object with speed (direction is not important at this stage) thrown into this "gravity well" will "orbit moving about the walls of the well but resistance would eventually bring it to rest in the bottom.

Now... the only problems with this representation is that an object may be so light that it would not even sink, and also objects have resistance, plus it is only 2 dimensional.

And... although there is sufficient evidence to state black holes exist they are yet to be proven and what we see know are computer generated models, what we know as hawking radiation is mostly made of photons and neutrinos.

in this model gravitational field is determined by mass, if your matter has mass it should have gravity.

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