0

Entropy has been increasing since the Big Bang. But how? It seems relatively intuitive, but the universe is cooling down. Often when things cool down, entropy decreases. So why, in the case of the universe, does it increase? What are the other factors that are causing entropy to increase?

Qmechanic
  • 220,844
Lara
  • 1
  • 2

1 Answers1

1

When a cup of hot water for example cools down, its entropy decreases. (Note however that there is a heat transfer to its neighbourhood, and the entropy of water + neighbourhood increases).

But if this cup of water is placed at the outer space, far from the sun, it also loses heat by radiation. But at the same time it boils away, increasing its entropy.

So, it is not true that by cooling down, a system always decreases its entropy.

Claudio Saspinski
  • 17,607