I happen[ed] to be studying astronomy [at the time I wrote the first draft of this post]. From my textbook:
“Our third crucial conservation law for astronomy is the law of conservation of energy. This law tells us that, like momentum and angular momentum, energy cannot appear out of nowhere or disappear into nothingness.”
* * *
“According to present understanding, the total energy content of the universe was determined in the Big Bang. It remains the same today and will stay the same in the future.”
Bennett, Jeffrey, The Cosmic Perspective: The Solar System (5th ed.), San Francisco:Pearson Addison-Wesley, 2008, pp. 130, 134.
Quite so. Energy can’t be created “out of nowhere” because it takes an infinite power to create anything out of nothing. And it can’t be destroyed for the same reason.
God created a certain amount of energy/matter at the Big Bang, and “objects can gain or lose energy only by exchanging energy with other objects.” (Id.)