Entropy and the Universe

The universe is a closed system by definition. This means that the laws of thermodynamics can be directly applied to it:

1. Energy cannot be created or destroyed, only transformed.
2. Energy will ultimately exhaust in useless entropy unless there is reversibility of process.

From this we have to conclude that any perpetual universe has to include reversibility to avoid an ultimate death through increasing entropy.

The perpetual universe is in other words a closed ideal system, also per definition.

Galaxy evolution from birth and death