>Breaking an egg is an irreversible process.
>
>But all the elements in that egg came from the stars and goes back to them.
>
>The elements will be spit out again 1 trillion years from now, or 1 trillion years ago.
>
>I'm not seeing the issue. Obviously the energy can't be lost, or there would be no energy left in the universe.
There are two important laws about energy, usually called the "First Law of Thermodynamics" and the "Second Law of Thermodynamics". The First Law is conservation of energy, which you just stated ("energy can't be lost").
The Second Law - in energy terms - states that
useful energy is constantly converted into
unusable energy. And indeed, the result of the Second Law would be - not that there is no energy left, but no
useful energy. And that is precisely one of the main objections against a static and eternal Universe.
>
>So it has to be dropped somewhere, probably to find its way back into a star, and then re-emitted as light at some point.
There is no way most of the emitted energy will find its way back into a star.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)