Modifying Gravity in the Infra-Red by imposing an "Ultra-Strong" Equivalence Principle

Understand

The equivalence principle suggests to consider gravity as an infra-red phenomenon, whose effects are visible only outside Einstein's free-falling elevator.

• By curving spacetime, General Relativity leaves the smallest systems free of classical gravitational effects.
• However, according to the standard semi-classical treatment, indirect effects of gravity can be experienced inside the elevator through the well-known mechanism of quantum particle production.
• Here we try a different path than the one historically followed: rather than imposing field quantization on top of a curved manifold, we attempt to upgrade the equivalence principle and extend it to the quantum phenomena.