@unpublished{Reiss2012,
  author    = {Reiss, Harald},
  title     = {Physical time and existence of time holes in non-transparent media},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67268},
  year      = {2012},
  abstract  = {The analysis presented in this paper applies to experimental situations where observers or objects to be studied (both stationary, with respect to each other) are located in environments the optical thickness of which is strongly different. By their large optical thickness, non-transparent media are clearly distinguished from their transparent counterparts. Non-transparent media comprise thin metallic films, packed or fluidised beds, the Earth's crust, and even dark clouds and other cosmological objects. As a representative example, a non-transparent slab is subjected to transient disturbances, and a rigorous analysis is presented whether physical time reasonably could be constructed under such condition. The analysis incorporates mapping functions that correlate physical events, e, in non-transparent media, with their images, f(e), tentatively located on a standard physical time scale. The analysis demonstrates, however, that physical time, in its rigorous sense, does not exist under non-transparency conditions. A proof of this conclusion is attempted in three steps: i) the theorem "there is no time without space and events" is accepted, (ii) images f[e(s,t)] do not constitute a dense, uncountably infinite set, and (iii) sets of images that are not uncountably infinite do not create physical time but only time-like sequences. As a consequence, mapping f[e(s,t)] in non-transparent space does not create physical analogues to the mathematical structure of the ordered, dense half-set R+ of real numbers, and reverse mapping, f-1f[e(s,t)] would not allow unique identification and reconstruction of original events from their images. In these cases, causality and determinism, as well as invariance of physical processes under time reversal, might be violated. Existence of time holes could be possible, as follows from the sequence of images, f[e(s,t)], that is not uncountably infinite, in contrast to R+. Practical impacts are expected for understanding physical diffusion-like, radiative transfer processes, stability models to protect superconductors against quenchs or for description of their transient local pair density and critical currents. Impacts would be expected also in mathematical formulations (differential equations) of classical physics, in relativity and perhaps in quantum mechanics, all as far as transient processes in non-transparent space would be concerned. An interesting problem is whether temporal cloaking (a time hole) in a transparent medium, as very recently reported in the literature, can be explained by the present analysis. The analysis is not restricted to objects of laboratory dimensions: Because of obviously existing radiation transfer analogues, it is tempting to discuss consequences also for much larger structures in particular if an origin of time is postulated.},
  subject      = {Strahlungstransport},
  language  = {en}
}