  Lorentz invariance requires local interactions, with force laws such as the
Coulomb interaction arising via virtual exchange of force carriers such as
photons. Many have considered the possibility that, at long distances or large
mass scales, this process changes in some way to lead to classical behavior.
Here we hypothesize that classical behavior could be due to an inability of
some force carriers to convey entanglement, a characteristic measure of
nonlocal, quantum behavior. We then prove that there exists a local test that
allows one to verify entanglement generation, falsifying our hypothesis.
Crucially, we show that noise measurements can directly verify entanglement
generation. This provides a step forward for a wide variety of experimental
systems where traditional entanglement tests are challenging, including
entanglement generation by gravity alone between macroscopic torsional
oscillators.
