  In this work we consider the ontological status of the Unruh effect. Is it
just a formal mathematical result? Or the temperature detected by an
accelerating observer can lead to real physical effects such as phase
transition. In order to clarify this issue we use the Thermalization Theorem to
explore the possibility of having a restoration of the symmetry in a system
with spontaneous symmetry breaking of an internal continuous symmetry as seen
by an accelerating observer. We conclude that the Unruh effect is an ontic
effect, rather than an epistemic one, giving rise, in the particular example
considered here, to a phase transition (symmetry restoration) in the region
close to the accelerating observer horizon.
