Quantum effects and quantum measurements on astrophysical space-times

• Applicant: Dr. Christiane Klein
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields ; Mathematics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531357976

Einstein’s theory of general relativity revolutionized our understanding of gravitation, and still inspires cutting-edge science. Firstly, this includes research on mysterious objects like black holes - considered unphysical mathematical curiosities, until Nobel-prize winning theoretical work by Roger Penrose. With the rapidly improving measurements of the gravitational waves from colliding black holes, and the first picture of the black hole in our own galaxy, they have become important observational objects. Secondly, Einstein’s general relativity also describes the evolution of our universe from the big bang to now. One central source of information about it is the cosmic microwave background (CMB), remnants of radiation from the distant past. In both examples, quantum effects play an important role. As our experimental data on black holes and the CMB improves, it becomes increasingly important to have a solid, mathematical description of these quantum effects to correctly predict and interpret experimental results like the gravitational wave data from next-generation detectors. My research will firstly produce a robust mathematical description of a quantum state on rotating black hole spacetimes. The rotation, which is common for black holes in our universe, makes the mathematical description notoriously difficult. My work will represent the physical situation arising at late times in the collapse of a spinning star. This will use recent major developments from the mathematical theory of partial differential equations. Secondly, my research will explore how the recently established measurement theory of quantum field theory, largely developed in York, can be applied to CMB measurements. This will illuminate what the measurements can tell us about the quantum fluctuations in the early universe. It will require extending the current boundaries of the measurement theory to include real experiments. The result will be on the forefront of research in mathematical physics and lay the foundation for the investigation of the evaporation of rotating black holes, the extension of the measurement theory of quantum field theory and the interpretation of the CMB measurements. Therefore, it will be an important step towards better understanding not only the quantum nature of our universe, but also quantum measurements and quantum field theory itself.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professor Dr. Christopher Fewster