- ENTROPY. It increases constantly.
- Relatedly, the eventual heat death of the universe.
- One day, the Sun will expand into a red giant.
- What if the universe just keeps expanding forever, never to bring forth a Big Crunch that might set forth a new Big Bang and thus potential for life?
- What if aliens don't exist and we're alone in the universe?
- Like seriously, the laws of thermodynamics. One is playing a game where one can only lose? And we can't quit?