Speaker
Description
We investigate a Schwarzschild metric exhibiting a signature
change across the event horizon, which gives rise to what we term a
Lorentzian-Euclidean black hole. The resulting geometry is regularized
by employing the Hadamard partie finie technique, which allows us to
prove that the metric represents a solution of vacuum Einstein
equations. In this framework, we introduce the concept of atemporality
as the dynamical mechanism responsible for the transition from a regime
with a real-valued time variable to a new one featuring an imaginary
time. We show that this mechanism prevents the occurrence of the
singularity and, by means of the regularized Kretschmann invariant, we
discuss in which terms atemporality can be considered as the
characteristic feature of this black hole. The physical foundation of
the approach can be related to the conservation laws. In fact, the black
hole is singularity free if Noether symmetries, related to the size and
the mass of the gravitational system, are not violated. In other words,
the emergence of imaginary time is the signature of a symmetry breaking.
In this perspective, it is not possible to enter the black hole, and the
event horizon becomes the limit of our knowledge according to the
standard laws of physics. Future challenges are related to the
observational signatures of atemporality which actually means that the
information comes only from the external black hole solution, and, in
addition, it is conserved. Other open issues are related to the quantum
counterpart of the model. In fact, we could conceive the event horizon
as a sort of potential barrier and the investigation of quantum
particles impacting against it could open an interesting phenomenology
to be explored.
