Recall that in quantum mechanics, unlike in classical mechanics, the problem of the dynamics of a system and the measurement of its properties are two different issues. The dynamics is governed by a differential equation, in our case the system's wave equation, Eq.(1). The measured properties are expressed by the expectation values of the appropriately chosen operators.
It is obvious that our present treatment of these two issues has been rather lopsided and we must address how to measure the imprints of gravitation with physically realizable apparatus. At first this seems like an impossibple task.
Consider the fact that that the quantum dynamics is governed by the evolution of the Klein-Gordon wave function in the two Rindler frames, Eq.(2), which (i) are accelerating eternally and (ii) are causally disjoint. How can one possibly find a physically realistic observer who can access such frames? It seems one is asking for the metaphysically impossible: an observer which can accelerate eternally and can be in causally disjoint regions of spacetime. There simply is no such observer!
However, we are asking the wrong questions because we have been
ignoring the two remaining Rindler sectors P
Space limitations demand that we consign the task of elaborating on this terse description to another article . The point is that the quantum mechanical carrier, Eq.(13), has a firm physical foundation while at the same time it exhibits the Eotvos property of being independent of the intrinsic mass of the quantum system.