 |
|
 |
|
 |
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
|
 |
|
|
Anthony Lasenby, Chris Doran and Reece Heineke Motivated by conventional gauge theories, we consider a theory
of gravity in which the Einstein-Hilbert action is replaced by a
term that is quadratic in the Riemann tensor. We focus on cosmological
solutions to the field equations in flat, open and closed universes.
The gravitational action is scale invariant, so the only matter
source considered is radiation. The theory can also accommodate
isotropic torsion and this generically removes singularities from
the evolution equations. For general initial conditions the Hubble
parameter H(t) is driven in a seemingly chaotic fashion by torsion
to produce irregularly occuring inflationary regions. In the absence
of torsion, the theory reproduces the standard cosmological solutions
of a simple big bang model. A satisfying feature is that a cosmological
constant arises naturally as a constant of integration, and does
not have to be put into the Lagrangian by hand. |
| back |
