12 research outputs found
Adiabatic and non-adiabatic perturbations for loop quantum cosmology
We generalize the perturbations theory of loop quantum cosmology to a
hydrodynamical form and define an effective curvature perturbation on an
uniform density hypersurfaces . As in the classical cosmology,
should be gauge-invariant and conservation on the large scales. The
evolutions of both the adiabatic and the non-adiabatic perturbations for a
multi-fluids model are investigated in the framework of the effective
hydrodynamical theory of loop quantum cosmology with the inverse triad
correction. We find that, different from the classical cosmology, the evolution
of the large-scales non-adiabatic entropy perturbation can be driven by an
adiabatic curvature perturbation and this adiabatic source for the
non-adiabatic perturbation is a quantum effect. As an application of the
related formalism, we study a decay model and give out the numerical results.Comment: 10 pages, 3 figure
Quantum gravity and the standard model
We show that a class of background independent models of quantum spacetime
have local excitations that can be mapped to the first generation fermions of
the standard model of particle physics. These states propagate coherently as
they can be shown to be noiseless subsystems of the microscopic quantum
dynamics. These are identified in terms of certain patterns of braiding of
graphs, thus giving a quantum gravitational foundation for the topological
preon model proposed by one of us.
These results apply to a large class of theories in which the Hilbert space
has a basis of states given by ribbon graphs embedded in a three-dimensional
manifold up to diffeomorphisms, and the dynamics is given by local moves on the
graphs, such as arise in the representation theory of quantum groups. For such
models, matter appears to be already included in the microscopic kinematics and
dynamics.Comment: 12 pages, 21 figures, improved presentation, results unchange
The View from The Blimp – Urban Image and the Telegenic Iconography of Sports Venues
Architecture_MPS is the academic journal of the research group AMPS (Architecture, Media, Politics, Society). It addresses the growing interest in the social and political interpretation of the built environment from a multi-disciplinary perspective. It engages with architecture, urbanism, planning, sociology, economics, cultural studies, visual culture, new medias and technologies. It draws on experts who bring emerging issues of international importance to the reader. Its publications are linked with a wide range of research programmes and conferences to further raise awareness of the social importance of architecture