A discrete-time interpretation of the Planck-Einstein equation.
The description of the special Reissner-Nordström space-time in the Planck era is presented and its comparison with the Robertson-Walker space-time is given.
Several situations of physical importance may be modelled by linear quantum fields propagating in fixed spacetime-dependent classical background fields. For example, the quantum Dirac field in a strong and/or time-dependent external electromagnetic field accounts for the creation of electron-positron pairs out of the vacuum. Also, the theory of linear quantum fields propagating on a given background curved spacetime is the appropriate framework for the derivation of black-hole evaporation (Hawking...