Modified Gravity

New Physics at Low Accelerations (MOND): an Alternative to Dark Matter

I describe the MOND paradigm, which posits a departure from standard physics below a certain acceleration scale. This acceleration as deduced from the dynamics in galaxies is found mysteriously to agree with the cosmic acceleration scales defined by the present day expansion rate and by the density of `dark energy'. I put special emphasis on phenomenology and on critical comparison with the competing paradigm based on classical dynamics plus cold dark matter. I also describe briefly nonrelativistic and relativistic MOND theories

Quantum Measurements and General Relativity

There are sticky issues when trying to understand how quantum measurement and general relativity might work together. Relativistic Model for Gravity-Induced Quantum State Reduction

A Lorentz invariant model for gravity-induced quantum state reduction is presented, which is mainly developed from the physical argument that the time translation operator in a superposition of macroscopic states is ill-defined. The model leads to a new approach how to overcome the basic problem of relativistic reduction models, the conflict between relativistic covariance and the assumption that state reduction leads to an abrupt change of the wave-function on a space-like hyperplane. Reductions are understood in the model as events on whole space-time regions instead on hyperplanes only. This view enforces a radical change for the formulation of the system's dynamics. A stochastic time flow running quasi orthogonal to the deterministic time evolution inside the four-dimensional space-time is proposed. It is shown that it is possible to formulate on the basis of this new view a meaningful physical model. The model is also checked for possible higher order effects, which provide new starting points for experimental research.