大下 翔誉 Naritaka Oshita

I am a theoretical physicist who works on gravity, cosmology, and quantum field theory. Quantum fluctuations of mater/gravitational fields in an expanding universe or a black hole exhibit thermal radiation and superradiance. These phenomena are important to understand the thermal nature of the gravitational systems and how information of matter is encoded there. Also, the classical linear perturbations of a black hole are characterized by the quasinormal modes of the black hole. This is useful to test classical/quantum gravity theories by the observation of gravitational waves.
Beyond the linear perturbation in gravitational systems, I am also working on non-perturbative phenomena of quantum fields such as vacuum decay in strong gravity. The standard model of particle physics predicts that the Higgs field is metastable, which means that our Universe might eventually undergo a catastrophic vacuum decay and be filled with negative vacuum energy. The vacuum decay process is therefore important to understand the history and fate of the Universe.