Entropy is basically the measure of the disorder
a system, or anything else. In a more in-depth view, entropy is
part of the Second Law of Thermodynamics. This law states that the
entropy, or disorder, of an isolated system is always increasing.
An example is a teacup. When it falls on the floor, it shatters
into many pieces, creating a more disorderly system; first there
was one piece of glass, now there are many more; and the disorder
can never decrease because the pieces can never jump up and pull
themselves together. Another example is a box with a partition in
the middle. On one side of the box is, say, pure hydrogen; on the
other side is pure nitrogen. When you remove the partition from
the middle of the box, the gases will begin to mix together, and
if you put the partition back, they will not go back to their original
sides. This shows that the entropy always increases, but never decreases.
The Second Law of Thermodynamics also states that when combining
two systems into one, its entropy will be greater than the sum of
the entropies of the two original systems by themselves. A strange
question that came about was what would happen if you threw, say,
the broken pieces of the teacup into a black hole; would the entropy
of our universe go down? There was no way to find out. Yet, a physicist
named Jacob Bekenstein said that the entropy of a black hole was
the area of the event horizon that served as its boundary. Yet,
a question still remained to be answered. If a black hole had entropy,
that means it emitted a certain type of radiation. But how could
that be possible if a black hole emitted nothing, due to its immense
gravitational force?
