Paired Accelerated

The geometrical and quantum mechanical basis for Davies' and Unruh's acceleration temperature is traced to a type of quantum mechanical (\achronal") spin. Its existence and deenition are based on pairs of causally disjoint accelerated frames. For bosons the expected spin vector of monochromatic particles is given by the \Planckian power" and the \r.m.s. thermal uctuation" spectra. Under space-time translation the spin direction precesses around that \Planckian" vector. By exhibiting the conserved achronal spin four-current, we extend the identiication of achronal spin from single quanta to multiparticle systems. Total achronal spin conservation is also shown to hold, even in the presence of quadratic interactions. In addition, the Lorentz invariance of the acceleration temperature is made explicit by the introduction of pairs of \spherical" Rindler frames. Classical mechanics was the starting point by which Newton and Einstein brought gravitation into our grasp. Newton's particle trajectories carry the imprint of grav-itational forces from which one can deduce the properties of gravitation and which hence led to Newton's equations for the gravitational potential. Einstein's world-lines, via geodesic deviation, carry the imprint of spacetime being curved, from which one can deduce gravitation as a manifestation of geometry, and which hence inevitably leads to Einstein's equations for the dynamics of the geometry. The actual world is however quantum mechanical in nature, and the starting point for gravitation should reeect this fact. Thus the imprints of gravitation should not be carried by classical particle worldlines but, more fundamentally, by wave functions or operators of quantum mechanics instead. 1. The Acceleration Temperature Nowadays, except for the energy E = h!, it is diicult to point to a purely quantum mechanical formula which is simpler than that of Davies-Unruh (D-U) for the acceleration temperature 1,2] kT = h c g 2 : (1.1) Can one therefore claim that in some way the simplicity of the D-U formula expresses a correspondingly fundamental aspect of nature? \fundamental" meaning that, given the context of our present day knowledge, this aspect serves to organize the y Based on a `raporteur report' of the session \Quantum Radiation and Accelerated Frames" originally