http://arxiv.org/abs/1602.01474
I clarify the differences between various approaches in the literature which attempt to link gravity and thermodynamics. I then describe a new perspective based on the following features: (1) As in the case of any other matter field, the gravitational field equations should also remain unchanged if a constant is added to the Lagrangian; in other words, the field equations of gravity should remain invariant under the transformation $T^a_b \to T^a_b + \delta^a_b $(constant). (2) Each event of spacetime has a certain number ($f$) of microscopic degrees of freedom (`atoms of spacetime’). This quantity $f$ is proportional to the area measure of an equi-geodesic surface, centered at that event, when the geodesic distance tends to zero. The spacetime should have a zero-point length in order for $f$ to remain finite. (3) The dynamics is determined by extremizing the heat density at all events of the spacetime. The heat density is the sum of a part contributed by matter and a part contributed by the atoms of spacetime, with the latter being $L_P^{-4} f$. The implications of this approach are discussed.
T. Padmanabhan
Fri, 5 Feb 16
28/47
Comments: Elaborates on the results presented in five recent talks: Keynote address in (i) EmQM15, Vienna, 23-25 Oct, 2015; Plenary talks in (ii) 35th Max Born Symposium – The Planck Scale II, Wroclaw, 7-12 Sept, 2015 and (iii) ICGC-2015, Mohali, 14-16 Dec 2015; Colloquia at (iv) IAP, Paris, 30 Oct 2015 and (v) TIFR, Mumbai, 5 Oct 2015; two figures, 26 pages
You must be logged in to post a comment.