Fluctuational QED
Radiation Pressure is a feature of non-equilibrium steady states with different temperatures
At short scales "near-field effects" due to evanescent waves modify classical "Stefan-Boltzmann" law:
"Surface Phonon Polaritons Mediated Energy Transfer between Nanoscale Gaps," S.Shen, A. Narayanaswamy, G. Chen
Nano Lett. 9, 2909 (2009) Breaking the law, at the nanoscale (MIT news, July 29, 2009)
A generalized approach for computation of Casimir forces, as well as radiation and heat transfer.
"Nonequilibrium Fluctuational QED: Heat Radiation, Heat Transfer and Force,"
G. Bimonte, T. Emig, M. Kardar, and M. Krüger, Annual Review of Condensed Matter Physics 8, 119 (2017)
S.M. Rytov (1959): "Fluctuational QED"
Fluctuating currents in each object are related to its temperature by a fluctuation-dissipation condition:
The EM field due to thermal fluctuations of one object is related to overall Green's function by:
The overall fluctuations with many objects at different temperatures is then given by:
From EM correlations follow the stress tensor and the Poynting vector, hence forces and radiation.
Heat transfer at short distances is dominated by evanescent modes at material dependent resonances.
For a single dominant frequency , the heat flux diverges at small separations as
Rytov formalism allows computation of fluctuations in force and heat, both in and out of thermal equilibrium
Linear response relates equilibrium fluctuations to responses to small perturbations:
Green Kubo relation (explicitly confirmed) provide coefficient of thermal conductivity
Friction coeficient in vacuum at finite temperature
Onsager relation (relying of symmetry of mixed expectation values) give
"Nonequilibrium Fluctuational QED: Heat Radiation, Heat Transfer and Force,"
V. Golyk, M. Krüger, and M. Kardar, Phys. Rev. B 88, 155117 (2013). (offline)