Introductions to the most inspired theses and books that I have read.

- E. P. Verlinde, "On the Origin of Gravity and the Laws of Newton", JHEP 04 (2011) 029, arXiv:1001.0785 [hep-th]
- K. Maruyama, et al. "Colloquium: The physics of Maxwell's demon and information", Rev. Mod. Phys. 81, 1 (2009)

This paper argues that the gravity is an entropic force. Entropic force is a virtual force like pressure. Ideal gas has pressure, but there is no repulsive forces between the molecules. The random motion of molecules and collisions to a wall results in pressure which seems as if there is a repulsive force. The random motion is temperature itself, so pressure is proportional to temperature(pv=RT). The proportionallity to temperature is an important feature of entropic forces.

Then what is the temperature of gravity? That is the difficult problem. In this paper, the author postulates that Unruh temperature determines gravity. From that hypothesis, and from some principles about entropy, fundamental principles are derived, Newton's equation of motion, Einstein equation.

But this theory has also a problem. This paper is cited by many other theses recently, and some of these point out that the temperature depends on the direction of gravity and the motion of a point mass.