““At first, one might think that something like thermodynamics is a rather restrictive concept because it concerns itself with temperature and heat. But its application is not just restricted to all things thermal. It is possible to relate the notion of entropy, which is a measure of disorder, to the more general and fruitful notions of 'information', of which we have already made use in discussing the richness of certain systems of axioms and rules of reasoning. We can think of the entropy of a large object like a black hole as being equal to the number of different ways in which its most elementary constituents can be rearranged in order to give the same large-scale state. This tells us the number of binary digits ('bits') that are needed to specify in every detail the internal configuration of the constituents out of which the black hole is composed. Moreover, we can also appreciate that, when a black hole horizon forms, a certain amount of information is forever lost to the outside observer when a horizon forms around a region of the universe to create a black hole.””
