5,608 research outputs found
Understanding Gravity: Some Extra Dimensional Perspectives
Gravity is one of the most inexplicable forces of nature, controlling
everything, from the expansion of the Universe to the ebb and flow of ocean
tides. The search for the laws of motion and gravitation began more than two
thousand years ago but still we do not have the complete picture of it. In this
article, we have outlined how our understanding of gravity is changing
drastically with time and how the previous explanations have shaped the most
recent developments in the field like superstrings and braneworlds.Comment: 21 page
Density Fluctuations in the Oscillatory Phase of Nonclassical Inflaton in FRW Universe
Using coherent and squeezed state formalisms of quantum optics for a
minimally coupled non-classical inflaton in the FRW mertic is studied, in
semiclassical theory of gravity. The leading order solution for the
semiclassical Einstein equations in the coherent, squeezed and squeezed vacuum
states are obtained perturbatively and are exhibit powerlaw expansion
behaviour. The validity of the semiclassical theory is examined in the squeezed
vacuum state in the oscillatory phase of the inflaton. The semiclassical theory
in the oscillatory phase of the non-classical inflaton holds only if the
associated squeezing parameter is much less compared to unity. Quantum
fluctuations of the inflaton is also examined in coherent and squeezed state
formalisms.Comment: 14 pages, 2 figures, To appear in Int.J.Mod.Phys.
Gravity and Large Extra Dimensions
The idea that quantum gravity can be realized at the TeV scale is extremely
attractive to theorists and experimentalists alike. This proposal leads to
extra spacial dimensions large compared to the electroweak scale. Here we give
a very systematic view of the foundations of the theories with large extra
dimensions and their physical consequences.Comment: 26 pages, 3 diagram
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