Thursday, July 20, 2006

Panning for Gold

Panning for Gold conference slac stanford edu

Panning for gold and more about LHC by JoAnne from SLAC

Any discovery or non-discovery at the LHC has zero implications for strings or LQG. This is particularly true for the Higgs. The only true exception is if TeV scale strings are discovered - that has obvious implications for string theory. Some will claim victory for string theory if supersymmetry is discovered. However, TeV scale supersymmetry can exist quite happily on its own merits without strings, so the discovery of supersymmetry at the LHC does not imply that string theory is correct. Proof of the existence of supersymmetry is a necessary, but not sufficient condition for proof of the existence of strings. Also, keep in mind that string theory does not require that supersymmetry be present at the TeV scale.


In supersymmetric theories, every fundamental particle has a superpartner. If the vacuum state happens to be supersymmetric, this would mean superpartners would have the same mass as their ordinary partners, which is clearly ruled out by experiment. Hence, the vacuum must have broken supersymmetry. Either we assume the vacuum is degenerate and SUSY is broken spontaneously, or we add soft SUSY breaking terms which break SUSY explicitly, making it an approximate symmetry. The latter approach is often preferred.

For more on Supersymmetry visit wikipedia

Image: ALFRED T. KAMAJIAN @ essentia holographic spacetime

Information in the Holographic Universe:
A Holographic Spacetime By Jacob D. Bekenstein

TWO UNIVERSES of different dimension and obeying disparate physical laws are rendered completely equivalent by the holographic principle. Theorists have demonstrated this principle mathematically for a specific type of five-dimensional spacetime ("anti–de Sitter") and its four-dimensional boundary. In effect, the 5-D universe is recorded like a hologram on the 4-D surface at its periphery. Superstring theory rules in the 5-D spacetime, but a so-called conformal field theory of point particles operates on the 4-D hologram. A black hole in the 5-D spacetime is equivalent to hot radiation on the hologram--for example, the hole and the radiation have the same entropy even though the physical origin of the entropy is completely different for each case. Although these two descriptions of the universe seem utterly unalike, no experiment could distinguish between them, even in principle.

black hole final state referencing by Plato

The Black Hole Final State
Gary T. Horowitz (1) and Juan Maldacena (2)
(1) University of California at Santa Barbara, Santa Barbara CA 93106, USA
(2) Institute for Advanced Study Princeton, New Jersey 08540, USA

We propose that in quantum gravity one needs to impose a final state boundary condition at black hole singularities. This resolves the apparent contradiction between string theory and semiclassical arguments over whether black hole evaporation is unitary.

The purpose of this note is to provide a possible answer to this question. Rather than the radical modification of quantum mechanics required for pure states to evolve into mixed states, we adopt a more mild modification. We propose that at the black hole singularity one needs to impose a unique final state boundary condition.

More precisely, we have a unique final wavefunction for the interior of the black hole. Here we are putting a final state boundary condition on part of the system, the interior of the black hole. This final boundary condition makes sure that no information is “absorbed” by the singularity.
Full pdf @ hep-th 0310/0310281

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