"Observational Constraints of Higher-Dimensional and Variable
Lambda Cosmologies"
James Overduin
University of Victoria
Nonstandard cosmological models of two broad classes are examined: those
in which there are more than four spacetime dimensions, and those in which
there is a variable cosmological "constant" Lambda. We test claims that a
number of higher-dimensional models give rise to inflation. New
constraints are placed on such models, and a number of them are ruled out.
We then investigate the potential of variable-Lambda theories to address
the problem of the initial singularity. We consider a number of different
phenomenological representations for this parameter, assessing their
implications for the evolution of the cosmological scale factor as well as
a range of observational data. In several cases we find nonsingular
models which are compatible with observation.
