Gravity as an Entropic Force

UPDATE, Feb. 18, 2008 - Lubos Motl has tossed another log on his Verlinde stake-burning here. The paper it refers to was just released today by Nature Magazine by Holger Muller, Achim Peters, and Stephen Chu, "A precision measurement of the gravitational redshift by the interference of matter waves". Since I do not subscribe to Nature, I cannot read the paper. Do any subscribers to Nature here care to comment, before Lubos weighs in?

I never thought I would see a cutting edge theory that would unite Lubos Motl and Peter Woit in agreement (they hate it), but here it is:

From Wikipedia, entry: Gravity as an entropic force:

The hypothesis of gravity being an entropic force has a history that goes back to the studies on black hole thermodynamics by Bekenstein and Hawking in the mid-70s of the twentieth century. These studies suggest a deep connection between gravity and thermodynamics. In 1995 Jacobson demonstrated that the Einstein equations describing relativistic gravitation can be derived by combining general thermodynamic considerations with the equivalence principle.^[1] Subsequently, other physicists have further explored the link between gravity and entropy.^[2]

Verlinde's statistical description of gravity as an entropic force leads to the correct inverse square distance law of attraction between classical bodies.

In 2009, Erik Verlinde disclosed a conceptual theory that describes gravity as an entropic force.^[3] This theory combines the thermodynamic approach to gravity with 't Hooft's holographic principle. If proven correct, gravity is not a fundamental force, but an emergent phenomenon which arises from the statistical behaviour of microscopic degrees of freedom encoded on a holographic screen.^[4]

Verlinde's suggestion of gravity being an entropic phenomenon attracted considerable media^[5][6] and weblog^{[7][8][9][10]} exposure, and led to immediate follow-up work in cosmology^[11][12], the dark energy hypothesis^[13], cosmological inflation^[14] and loop quantum gravity^[15]. Also, a specific microscopic model has been proposed^[16] that indeed leads to entropic gravity emerging at large scales.

1. ^ Thermodynamics of Spacetime: The Einstein Equation of State, Ted Jacobson, 1995
2. ^ Thermodynamical Aspects of Gravity: New insights, Thanu Padmanabhan, 2009
3. ^ http://www.volkskrant.nl/wetenschap/article1326775.ece/Is_Einstein_een_beetje_achterhaald Dutch newspaper 'Volkskrant', 9 December 2009
4. ^ On the Origin of Gravity and the Laws of Newton, Erik Verlinde, 2010
5. ^ The entropy force: a new direction for gravity, New Scientist, 20 January 2010, issue 2744
6. ^ Gravity is an entropic form of holographic information, Wired Magazine, 20 January 2010
7. ^ Holographic Hot Horizons, Johannes Koelman, 14 December 2009
8. ^ Gravity as a holographic entropic force, Luboš Motl, 7 January 2010
9. ^ It from Bit: the case of gravity, Johannes Koelman, 7 January 2010
10. ^ The entropy decade, Peter Woit, 11 January 2010
11. ^ Equipartition of energy and the first law of thermodynamics at the apparent horizon, Fu-Wen Shu, Yungui Gong, 2010
12. ^ Friedmann equations from entropic force, Rong-Gen Cai, Li-Ming Cao, Nobuyoshi Ohta 2010
13. ^ It from Bit: How to get rid of dark energy, Johannes Koelman, 2010
14. ^ Towards a holographic description of inflation and generation of fluctuations from thermodynamics, Yi Wang, 2010
15. ^ Newtonian gravity in loop quantum gravity, Lee Smolin, 2010
16. ^ Notes concerning "On the origin of gravity and the laws of Newton" by E. Verlinde, Jarmo Makela, 2010

....