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State refinements and coarse graining in a full theory embedding of loop quantum cosmology

Dec 14
Group Seminar
6:00 pm o'clock to 7:30 pm o'clock
Dr. Norbert Bodendorfer (LMU)
SR 02.729

Bridging between descriptions involving few large and many small quantum numbers is
the main open problem in loop quantum gravity. In other words, one would like to be
able to represent the same physical system in terms of a few “coarse” quantum
numbers, while the effective dynamics at the coarse level should agree with the one
induced by a description involving many small quantum numbers. Efforts to understand
this relationship face the problem of the enormous computational complexity involved
in evolving a generic state containing many quanta. In a cosmological context
however, certain symmetry assumptions on the quantum states allow to simplify the
problem. In this talk, we will discuss how quantum states describing a spatially
flat homogeneous and isotropic universe can be refined while the dynamics of the
coarse observables is unchanged. The involved states are solutions to the
Hamiltonian constraint when terms coming from spatial derivatives are neglected,
i.e. one works in the approximation of non-interacting FRW patches. The technical
means to arrive at this result are a version of loop quantum gravity based on
variables inspired by loop quantum cosmology, as well as an exact solution to the
quantum dynamics of loop quantum cosmology which extends to the full theory in the
chosen approximation.