Speaker
Description
"A promising route toward understanding how spacetime may emerge from quantum gravity is to regard gravitational dynamics in minisuperspace as a hydrodynamic or collective limit of the underlying theory. One intriguing indication of such an emergent structure is the recurring appearance of Schrödinger symmetry in a variety of minisuperspace models. While recent work in quantum cosmology has extended this perspective to increasingly nontrivial settings, studies of static, spherically symmetric spacetimes have so far focused mainly on vacuum black-hole models. It is therefore important to ask whether Schrödinger symmetry persists once matter degrees of freedom are included.
In this talk, based on joint work with Yuki Yokokura (Kochi University of Technology), published in Phys. Rev. D 114 (2026) 024055, I will discuss static, spherically symmetric minisuperspace models coupled to matter fields. We identify three-dimensional Schrödinger symmetry in two physically distinct systems. The first consists of gravity coupled to a Maxwell field and a cosmological constant, whose classical solutions include charged Reissner–Nordström–(A)dS black holes. The second consists of gravity coupled to a massless scalar field. This case is particularly interesting because it gives rise classically to the Janis–Newman–Winicour (JNW) spacetime, which contains a naked singularity, while a massless scalar field can also serve as a relational clock in extracting classical spacetime dynamics from quantum gravity.
Interestingly, the two matter-coupled models require different choices of the lapse function and minisuperspace variables to make the Schrödinger symmetry manifest. Nevertheless, in the vacuum limit both constructions reduce to the Schwarzschild minisuperspace, where two-dimensional Schrödinger symmetry is realized in both descriptions. This provides partial evidence that the symmetry is not merely an artifact of a particular choice of lapse or minisuperspace coordinates. More broadly, our results show that Schrödinger symmetry survives the inclusion of nontrivial matter degrees of freedom, supporting its robustness as an emergent structure in gravitational minisuperspace and strengthening the possible connection between gravity and quantum hydrodynamics."