Symmetry and the order of events in time: The thermodynamics of blackbodies composed of positive or negative mass

I have previously proposed a discrete symmetry called CPM (charge-parity-mass) symmetry that defines matter as having positive mass and antimatter as having negative mass|both being involved in processes that proceed forward in time. I have generalized the second law of thermodynamics to describe and predict the order of events in time that take place in reversible thermodynamic systems composed of positive or negative mass. Here I extend the CPM symmetry to irreversible thermo-optical radiation systems characterized by the Stefan{Boltzmann law,Planck s blackbody radiation law,and Einstein s law of specific heat. The laws of radiation analyzed in terms of CPM symmetry may provide a fresh way of understanding old topics such as the photon and entropy and new topics such as the nonluminous substances in the universe known as dark matter. © TÜBITAK.