56 research outputs found
Scaling Relations for the Cosmological "Constant" in Five-Dimensional Relativity
When the cosmological "constant" is derived from modern five-dimensional
relativity, exact solutions imply that for small systems it scales in
proportion to the square of the mass. However, a duality transformation implies
that for large systems it scales as the inverse square of the mass
Astrophysical Implications of Higher-Dimensional Gravity
We review the implications of modern higher-dimensional theories of gravity
for astrophysics and cosmology. In particular, we discuss the latest
developments of space-time-matter theory in connection with dark matter,
particle dynamics and the cosmological constant, as well as related aspects of
quantum theory. There are also more immediate tests of extra dimensions,
notably involving perturbations of the cosmic 3K microwave background and the
precession of a supercooled gyroscope in Earth orbit. We also outline some
general features of embeddings, and include pictures of the big bang as viewed
from a higher dimension.Comment: 23 pages, 2 figures; to appear in Space Science Reviews; v3: typos
corrected and minor changes to text, expanded derivation of fundamental mode
adde
Limits on violations of Lorentz Symmetry from Gravity Probe B
Generic violations of Lorentz symmetry can be described by an effective field
theory framework that contains both general relativity and the standard model
of particle physics called the Standard-Model Extension (SME). We obtain new
constraints on the gravitational sector of the SME using recently published
final results from Gravity Probe B. These include for the first time an upper
limit at the 10^(-3) level on the time-time component of the new tensor field
responsible for inducing local Lorentz violation in the theory, and an
independent limit at the 10^(-7) level on a combination of components of this
tensor field.Comment: 8 pages, 1 figur
Waves and causality in higher dimensions
We give a new, wave-like solution of the field equations of five-dimensional
relativity. In ordinary three-dimensional space, the waves resemble de Broglie
or matter waves, whose puzzling behaviour can be better understood in terms of
one or more extra dimensions. Causality is appropriately defined by a null
higher-dimensional interval. It may be possible to test the properties of these
waves in the laboratory.Comment: 15 pages, no figure
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