 Second, what is the scope of the Second Law? There are two issues here. First, does it apply to the universe as a whole, so that we can say the universe’s entropy is increasing, or does it only apply to select sub-systems of the universe? (See Uffink 2001 for an interesting historical discussion of this topic.) Many philosophers and physicists have balked at the idea that the universe itself has an entropy. As one might expect, those in the grip of an operationalist philosophy are especially prone to deny that the universe as a whole has an entropy. Second, what sub-systems of the universe does it govern? Are the principles of thermodynamics responsible for generalizations about black holes? The field of black hole thermodynamics assumes it is (see the section on black hole thermodynamics in the entry on  singularities and black holes,  for discussion and references), although not all are convinced (Dougherty &amp; Callender forthcoming). What about the micro-realm?