Akbar and Cai [19] found that the Friedmann equations at the apparent horizon can be written in the form dE = TdS + WdV (E, V, and W are the energy, volume inside the horizon, and work density, resp.) in general relativity (GR), GB gravity, and the general Lovelock

theory of gravity. In modified theories, an additional entropy production term appeared in Clausius relation that corresponds to the nonequilibrium behavior of thermodynamics while no extra term appears in GB gravity, Lovelock gravity, and braneworld gravity [20-24].

It's the first comprehensive

theory of gravity since Sir Isaac Newton published The Principia 400 years ago, since then we've only thought mass attracted other mass.

LQG is relatively less ambitious, in the sense that it primarily aims to be a consistent

theory of gravity without trying to achieve any grand unification of sorts.

While Newton's

theory of gravity is mostly good enough to describe the motions of the solar system, it is around very dense objects like pulsars and black holes that general relativity becomes indispensable.

Newton published his

theory of gravity in his much celebrated work the Principia (1686) but there was some controversy.

And where would science be without the falling fruit that led Isaac Newton to form his

theory of gravity?

Over the past quarter century, new observations and phenomenological models have propelled cosmology forward; at the same time, once-shy string theory has been filling out as a possible candidate for a quantum

theory of gravity. But some obstacles remain before The Big Untying can be consummated: theorists would like a microscopic understanding of the effective theories of the early universe, and truth to tell, the physics close to the initial singularity are still a bit obscure.

The account of Newton's eureka moment, which led to his famous

theory of gravity, forms part of William Stukeley's 1752 biography of the great scientist.

But gut is consistent with Quantum Theory, and scientists have struggled to formulate a

theory of gravity that is also consistent with Quantum Theory.

Settlement building defies Isaac Newton's

theory of gravity that can now be modified: What goes up will probably never come down.

Some physicists are even willing to burn down their old sainted Einstein and revise his

theory of gravity, general relativity, to make the cosmic discrepancies go away.

They have since become accepted as a natural consequence of general relativity, Albert Einstein's

theory of gravity.