17,020 research outputs found
Holography and Stiff-matter on the Brane
Recently, Verlinde noted a surprising similarity between Friedmann equation
governing radiation dominated universe and Cardy's entropy formula in conformal
field theory. In this note, we study a brane-universe filled with radiation and
stiff-matter. We analyze Friedmann equation in this context and compare our
results with Cardy's entropy formula.Comment: 6 pages, Latex, references added to match with published versio
The Holography Hypothesis in Pre-Big-Bang Cosmology with String Sources
The holographic ratio in Pre-big bang string cosmology is obtained in the
presence string sources. An iterative procedure is adopted to solve the
equations of motion and derive the ratio in four dimensional world. First the
zeroth order ratio is computed in the remote past, i.e. at , then
the holographic ratio is obtained taking into account the evolution of the
backgrounds following the iterative procedure. The corrections to the zeroth
order value of the ratio depends on the form of the initial number distribution
of the strings chosen. Moreover, we estimate the holographic ratio in the
recent past (i.e. when ) and in the remote past (i.e. when
), , in different dimensions in the
Einstein frame and in the string frame. We find that in the first case it has
similar time dependences in both the frames, especially in four dimensions the
ratio is explicitly computed to be the same in the two cases, whereas for
case the time dependence is different.Comment: 33 pages, latex, five figure
- …