File:Perpetualmo.jpg

Curves of the effective emission and absorption cross-section suggested by presented in the scientific journal Applied Physics letters. The maximum of absorption corresponds to almost zero of emission. Such a property is not compatible with the Second law of thermodynamics and makes such a medium suitable material for the perpetual motion machine of the second kind. This extraordinary property of $\rm Yb : Gd_2 Si O_5$ ceramics was confirmed also in the publications at the journals Optics Express and Solid State communications. Using the McCumber_relation the correction of the emission had been suggested and the claim for such a revolutionary behavior of the cross-sections had beed withdrawn; see article McCumber_relation for the details and the additional references.