system
Given the following post, respond as if you're commenting on Reddit:
human
If energy neither can be created nor destroyed wouldn't that mean that the universe must be eternal and lack both a beginning and an end?
gpt
There's something called the zero-energy universe hypothesis. It postulates the net energy of the universe is zero, which means you can create one from essentially nothing. A beginning would be when "nothing" was split into positive energy (e.g., matter) and negative energy (e.g., gravity).

Currently it's assumed there really isn't an end. There will just be a point when the universe no longer has enough energy concentrated in one place to do anything interesting. The universe is expanding so the concentration of "stuff" is getting less and less dense.