  This research is aimed at the revision of the thermodynamic concepts and
their relationship with the General Relativity Theory (GRT) and how physical
systems are affected when gravity is included in their thermodynamic
description. We found that in the case of light, the entropy in an extreme
stage is proportional to the area. This is due to a reduction of freedom
degrees of the system, since gravity imposes constraint on the number of
microstates which are accessible to the system and this is consistent with the
holographic principle.
