Einstein's basement - A kinematic sector complementing special relativity

Abstract

We revisit the concept of particles as it is used in special relativity. The presented model treats the energy-momentum relation of relativistic particles as the upper branch of a generalized energy-momentum relation of quasi particles. These particles emerge from a forbidden crossing between the constant energy of a massive particle in rest and the linear energy momentum relation of a massless particle. The lower branch, a regime dubbed as Einstein's basement, gives rise to particles with different kinematics that is analyzed in the low-velocity limit. Allowing for gravitational interaction between those particles we find both attraction and repulsion, depending on their velocity with respect to an absolute space. This absolute frame is only relevant for Einstein's basement and does not affect the relativistic dynamics of regular matter as long as no coupling between the branches is considered, while weak coupling induces local Lorentz violations. We finally discuss whether our approach can be used to model phenomena of dark matter and dark energy.