In the presence of a minimal uncertainty in length, there exists a critical temperature above which the thermodynamics of a gas of radiation changes drastically. We find that the equilibrium temperature of a system composed of a Schwarzschild black hole surrounded by radiation is unaffected by these modifications. This is in agreement with works related to the robustness of the Hawking evaporation. The only change the deformation introduces concerns the critical volume at which the system ceases to be stable. On the contrary, the evolution of the very early universe is sensitive to the new behavior. We readdress the shortcomings of the standard big bang model (flatness, entropy, and horizon problems) in this context, assuming a minimal coupling to general relativity. Although they are not solved, some qualitative differences set in.

• Received 30 June 2003

DOI:https://doi.org/10.1103/PhysRevD.68.125005