sci.physics

>From Osher Doctorow

The keyword "holographic" on arXiv brings forth 473 papers including
84 papers in 2007, the latest of which include combining the
Holographic Principle of 't Hooft with:

1) generalized Chaplygin gas (for expansion of the Universe)
2) trace anomalis
3) hessence models
4) tachyon models
5) entropy
6) local quantum field theory

and so on.

I couldn't find "entropy of entanglement" in Wikipedia or Wolfram
(after noticing a paper on it - see below), but something called QWIKI
(http: // /wiki/entropy_of_entanglement) defines it as
the expectation of w given a pure state |w> and a partition {A, B} for
a system where the expectation of w is in turn defined as the von
Neumann entropy S(rho_A) = S(rho_B) where S(rho) is defined as -trace
of rho log_2(rho) and rho_A is defined as the trace with respect to B
of |w>
Veronika E. Hubeny of Science Labs Durham . and M. Rangamani of the
same place and T. Takayangi of Kyoto U. Japan have a paper on a
covariant holographic entanglement entropy proposal, arXiv:
v2 [hep-th] 25 Jul 2007, 72 pages. One thing that they argue is that
Euclidean Wormhole geometries with multiple boundaries should be
regarded as states in a non-interacting but entangled set of QFTs, one
associated to each boundary.

The most recent paper on holography is by Chinese researchers at
Dalian U. of Technology and KAVLI Institute China, "Holographic dark
energy in a cyclic universe," arXiv: v1 [hep-th] 23 Aug
2007, 13 pages, by Jingfei Zhang, Xin Zhang, and Hongya Liu. The
second author has almost 70 papers in arXiv including about 26 in
2007, while the 3rd author has 41 papers in arXiv including 13 in 2007
but only began in arXiv in 2000. It is a fascinating paper which
allows similar interpretations from both Loop Quantum Gravity (LQG)
and Brane/Braneworld theory like Randall-Sundrum. It involves high
and low energy scenarios and differential equations for the
holographic evolution of the Universe with Holographic Dark Energy
increasing and decreasing in importance (the latter makes it a
quintessence-like component). Their connection with Inflation seems
inadequately developed and their acceptance of a "bounce" instead of a
real Big Bang seems like Mainstream Dogmatism especially associated
with the LQG school. Probable Causation/Influence (PI) enters via
Generalized Logistic Differential Equations with time replaced by
log(scale factor) and similarly with dy/dt replaced by 3H^2 for H =
(da/dt)/a as the Hubble parameter.

Osher Doctorow