MG13 - Talk detail

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The entropic gravity scenario recently proposed by Erik Verlinde reproduced the Newton's law of purely classical gravity yet the key assumptions of this approach all have quantum mechanical origins. This is atypical for emergent phenomena in physics, where the underlying, more fundamental physics often reveals itself as corrections to the leading classical behavior. So one naturally wonders: where is ~ hiding in entropic gravity? To address this question, we rst revisit the idea of holographic screen as well as entropy and its variation law in order to obtain a self-consistent approach to the problem. Next we argue that when dealing with quantum gravity issues the generalized uncertainty principle (GUP) should be the more appropriate foundation. Indeed based on GUP it has been demonstrated that the black hole Bekenstein entropy area law must be modied not only in the strong but also in the weak gravity regime. In the weak gravity limit, such a GUP modied entropy exhibits a logarithmic correction term. When applying it to the entropic interpretation, we demonstrate that the resulting gravity force law does include sub-leading order correction terms that depend on ~. Such deviation from the classical Newton's law may serve as a probe to the validity of the entropic gravity postulate.

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We introduce a new model of gamma ray burst (GRB) that explains its observed prompt signals, namely, its primary thermal spectrum and high energy tail. This mechanism can be applied to either assumption of GRB progenitor: coalescence of compact objects or hypernova explosion. The key ingredients of our model are: (1) The initial stage of a GRB is in the form of a relativistic quark-gluon plasma “lava"; (2) The expansion and cooling of this lava results in a QCD phase transition that induces a sudden gravitational stoppage of the condensed non-relativistic baryons and form a hadrosphere; (3) Acoustic shocks and Alfven waves (magnetoquakes) that erupt in episodes from the epicenter efficiently transport the thermal energy to the hadrospheric surface and induce a rapid detachment of leptons and photons from the hadrons; (4) The detached e+e− and γ form an opaque, relativistically hot leptosphere, which expands and cools to T ∼ mc^2, or 0.5 MeV, where e+e− → 2γ and its reverse process becomes unbalanced, and the GRB photons are finally released; (5) The “mode-conversion" of Alfven waves into electromagnetic waves in the leptosphere provides a “snowplow” acceleration that gives rise to the high energy spectrum of GRB. According to this model, the observed GRB photons should have a red-shifted peak frequency at Ep ∼ Γ (1 + β/2)mc^2/(1 + z), where Γ ∼ O(1) is the Lorentz factor of the bulk flow of the lava, which may be determined from the existing GRB data.

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