Semiclassical Gravitation

• Applicant: Professor Dr. Detlef Dürr (†)
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields ; Mathematics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264569680

The unification of quantum theory with gravity is still an open problem. The application of standard quantization rules to classical general relativity has led to a number of conceptual and technical problems (like the problem of time, finding solutions to the Wheeler-DeWitt equation, etc.). Therefore one often resorts to a semi-classical approximation. In this approximation, gravity is treated classically, being described by a space-time metric, while matter, say a scalar field, is treated as a quantum field on curved space-time, taking the quantum mechanical average of the energy stress tensor.Still this treatment suffers from the notorious measurement problem: A superposition of spatially separated wave packets (Schrödinger cat states) would generate a gravitational field which suggests that there is matter here and there, while according to Born's rule matter could be only here or there. The measurement problem is solved by Bohmian mechanics and it is therefore natural to apply Bohmian mechanics in semiclassical situations. We shall study this approach to semi classicality starting from simpler models and ending in a better semiclassical theory of gravity with sharper results than the ones achieved until now. Experimental verifications of our sharper results are feasible. The work is planned in collaboration with Dr. Ward Struyve (now Rutgers) as Post Doc.

• DFG Programme: Research Grants