  We point out that neutrino oscillations imply an ambiguity in the definition
of the vacuum and the coupling to gravity, with experimentally observable
consequences due to the Unruh effect. In an accelerating frame, the detector
should see a bath of mass Eigenstates neutrinos. In inertial processes,
neutrinos are produced and absorbed as charge Eigenstates. The two cannot be
reconciled by a spacetime coordinate transformation. This makes manifestations
of the Unruh effect in neutrino physics a promising probe of both neutrinos and
fundamental quantum field theory. In this respect, we suggest $p\rightarrow n
+\ell^+ + {\nu_\ell}$ ($\ell^+ = e^+, \mu^+, \tau^+$) transitions in strong
electromagnetic fields as a promising avenue of investigation. In this essay we
discuss this process both in the inertial and comoving frame, we briefly
describe the experimental realization and its challenges, and close by
speculating on possible results of such an experiment in different scenarios of
fundamental neutrino physics
