Verlinde, LQG, entropy and gravity as a fundamental force vs emergent

[tom.stoer]

Gravity makes me think about mass. But mass is not an issue here, but entropy. Entropy is not quantized, but is a consequence of quantization. So, the only thing left here to quantize is geometry and the fields that lives on it.

(quasi-local) mass is a very difficult and derived concept in GR ...

 

[MTd2]

I don't get what you are saying.

 

[tom.stoer]

quasi-local mass is a derived concept in GR that is not completely understood; you don't need it for the dynamics of gravity; all you need is energy-momentum density

 

[MTd2]

But energy tensor ends up involving point masses anyway, which will end up in geometry controlled by mass terms.

 

[tom.stoer]

But energy tensor ends up involving point masses anyway, which will end up in geometry controlled by mass terms.

No, it doesn't. Mass means integrating a voluem form which is tricky in curved spacetime. Forget about mass. It's not an energy tensor, it's an energy-momentumdensity tensor.

 

[MTd2]

Density is still a mass term.

 

[tom.stoer]

Formally the Einstein equations tell you that the action of an operator containing purely geometric degrees of freedom equates to something containing other (= "matter") degrees of freedom. If you want to separate geometry and gravity you have to make sense of "quantized geometry" alone = w/o taking into account the dynamics of the matter degrees of freedom = w/o taking into account dynamics. But I don't know how to separate geometry from dynamics b/c both have the same origin; that's one lesson of GR.

 

[MTd2]

Hmm, I guess what I am arguing here is the nature of matter after all. The concept is so weird that I got confused.