When a box of nitrogen with an entropy of 1 is mixed with a box of oxygen with an entropy of also 1 then you get a box with an entropy of 3. Perhaps a bit simplified but why is always the total entropy of two joint boxes bigger than the sum of the entropy of the boxes?
And the same is valid for colliding black holes. When two BH of the same size are collided you get a BH with an entropy which is bigger than the sum of the entropy of the singel BH. What causes this and is the reason for this the same as in the first example above?
