Microscopic black holes explode with their temperature varying inversely as their mass .
Such explosions would lead to the highest temperatures in the present universe , all the way to the Planck energy .
The possibility that a quasi-stationary shell of hot matter surrounds these black holes has recently been proposed and studied with relativistic Boltzmann transport equations and with relativistic viscous fluid dynamics .
For example , a black hole with a mass of 10 ^ { 10 } g has a Hawking temperature of 1 TeV , a Schwarszchild radius of 1.6 \times 10 ^ { -5 } fm , a luminosity of 7 \times 10 ^ { 27 } erg/s , and has less than 8 minutes to live .
It is an outstanding theoretical challenge to describe the conditions exterior to such microscopic black holes and a great challenge to finally detect them in the new millennium .