Hawking radiation is supposed to emanate from black holes because black holes have a temperature. A black hole has to be about 3 times the solar mass. A black hole with a few times the mass of the sun would have a temperature of only one ten millionth of a degree above absolute zero. This is much lower than the 2.7 K ambient temperature of the microwave background radiation. We know that the second law of thermodynamics requires that heat only flow from a hotter to a colder body. Thus it would seem Hawking radiation would not be practically possible in the present universe - it is only a theoretical principle. As for mini black holes in the early universe, even though mini black holes would be hotter, the early universe would also have been hotter. So mini black holes would radiate and explode only if they were hotter than the ambient temperature. What do you guys have to say about this temperature differential issue?