I realized that everything in the universe can only increase in size and not decrease. Because the entropy is growing, but in the other hand, according to hawking a black hole which not "devour" anything actually lose mass (Hawking radiation), and after a certain time (million or billion of years) it eventually explode, so the entropy growing, but the mass of a black hole decrease, what's really happen?
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$\begingroup$ "I realized that everything in the universe can only increase in size and not decrease" Lots of things in the universe get smaller; not just black holes. Do you think it is impossible for people to lose weight? $\endgroup$– D. HalseyCommented Dec 15, 2018 at 1:30
1 Answer
The mass itself is not very relevant here. But energy is conserved. You have mass and energy in an ordered state. It forms a black hole and is radiated away with a higher entropy. Once everything is radiated away the energy is still the same, its form has changed (star and stuff to BH to radiation), but energy is conserved. However, the entropy has increased, as it is now in very diffuse radiation, spread over all possible directions, so it is less ordered.