New Insights on the Thermodynamic Equilibrium of Black Hole and Thermal
  Radiation
  The thermal balance between the black hole and surrounding thermal radiation
is an interesting topic. The primordial black hole is a type of black hole
formed in the early universe, especially during the thermal radiation period of
the early universe. Driven by gravity, thermal radiation will collapse to form
a black hole. Because of the complexity of the actual situation, we use the
simplest model for simulation under the premise of only considering the
thermodynamic properties of the system: in the classic case, an isolated box
full of thermal radiation, by adjusting the initial temperature within a
reasonable range, the results show that the collapse of part of the thermal
radiation to form a black hole and finally achieve thermal equilibrium is an
inevitable result of the second law of thermodynamics. We then introduced the
quantization of black holes and the number of microscopic states of thermal
radiation into the thermal equilibrium system and came to a surprising
conclusion: if both the quantization of black holes and the number of
microscopic states of thermal radiation are considered at the same time, the
fluctuation of thermodynamics is inevitable. When only one of them is
considered, the law of conservation of energy and the second law of
thermodynamics can be satisfied at the same time, and the fluctuation of
thermodynamics can be avoided. This provides a new way of thinking for us to
understand the microscopic origin of thermodynamic fluctuations.
