Classical Physics of Thermal Scalar Radiation in Two Spacetime Dimensions

Abstract Thermal scalar radiation in two spacetime dimensions is treated within relativistic classical physics. Part I involves an inertial frame where are given the analogues both of Boltzmann’s derivation of the Stefan-Boltzmann law and also Wien’s derivation of the displacement theorem using the σltU−1-scaling of relativistic radiation theory. Next the spectrum of classical scalar zeropoint radiation in an inertial frame is derived both from σltU−1-scale invariance and from Lorentz invariance. Part II involves the behavior of thermal radiation in a coordinate frame undergoing (relativistic) constant acceleration, a Rindler frame. The radiation normal modes in a Rindler frame are obtained. The classical zero-point radiation of inertial frames is transformed over to the coordinates of a Rindler frame. Although for zero-point radiation the two-field correlation function at different spatial points at a single time is the same between inertial and Rindler frames, the correlation function at two different times at a single Rindler spatial coordinate is different, and has a natural extension to non-zero temperature. The thermal spectrum in the Rindler frame is then transferred back to an inertial frame, giving the familiar Planck spectrum.