  If the information transfer between test particle and holographic screen in
entropic gravity respects both the uncertainty principle and causality, a lower
limit on the number of bits in the universe relative to its mass may be
derived. Furthermore, these limits indicate particles that putatively travel at
the speed of light -- the photon and/or graviton -- have a non-zero mass $m
\geq 10^{-68}~$kg. This result is found to be in excellent agreement with
current experimental mass bounds on the graviton and photon, suggesting that
entropic gravity may be the result of a (recent) softly-broken local symmetry.
Stronger bounds emerge from consideration of ultradense matter such as neutron
stars, yielding limits of $m \geq 10^{-48}-10^{-50}~$kg, barely within the
experimental photon range and outside that of the graviton. We find that for
black holes these criteria cannot be satisfied, and suggest some possible
implications of this result.
