Thermal Radiation Field of Two Half-Space in Contact with Different Temperatures

By using the fluctuation dissipation theorem in electro-magnetic circuits, the thermal radiation energy density at any point of two half-space in contact with different temperatures derived. By approximate expansion of the derived equations, the temperature expressions at any point are obtained, which are exactly similar to that obtained by Grover and Urtiew except there appears an additional relaxation term which is also existent in the method of non-Fourier heat conduction. The result is in accord with that of the experimental and the relaxation time can be calculated by the properties of the material.