gravity.phy.umassd.edu

This section is dedicated to the ongoing research projects of our group related to loop quantum cosmology. Initials of the faculty involved, are in parentheses.

Projects

• Numerical solutions in Loop Quantum Cosmology (MB,DC,GK)

Loop quantum cosmology (LQC) is a symmetry reduced application of loop quantum gravity (LQG), that has recently led to the emergence of a quantum mechanism for cosmic inflation, resolution of classical singularities and more. Since spacetime is discrete in LQG, the evolution equations one obtains in such models are discrete difference equations, that do not generically yield smooth solutions in the semi-classical limit. We have developed a variety of techniques to obtain meaningful physical solutions, i.e. solutions to these models that do have the proper limiting smooth behavior. Here is a movie and snapshot, showing the dynamics of discrete quantum space using the basic principles of LQG: spinfoam, snapshot.

• Homogeneous Loop Quantum Cosmology (MB,DC,GK)

Homogeneous and isotropic cosmologies have been studied quite extensively in LQC. This project is about anisotropic models, i.e. Bianchi cosmologies and their solutions in the context of LQC. These models are relevant for an understanding of the very early Universe.

• Black Holes in Loop Quantum Gravity (MB,DC,GK)

Loop quantum gravity also resolves the singularities that are present in the interior of black holes. One interesting thing that we have recently uncovered is that an evolution through such a singularity, provides an indication of different physics on the other side, which could be evidence of parameter change (see below). Here is a plot that indicates a different behavior in the wave-function of the Universe, it is passes through the classical Singularity: plot.

• Parameter change and Cosmological Natural Selection (DC,GK)

Cosmological Natural Selection (CNS) is an idea that was proposed by Lee Smolin in his popular book, The Life of the Cosmos. The basic thesis of CNS is that the physical constants of Nature appear to be tuned to ensure that Black Holes arise and proliferate. Smolin speculates on a mechanism for change in the physical constants as we stated above. This project is related to making further investigations into probing the validity of CNS.