system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When physics says that information can never be completely destroyed, what is this "information" it talks about?
gpt
Think about it like this. If we knew exactly where everything is right now, we could follow it back to find out anything we wanted to about the past. As such, the present must contain the information needed to describe the past.

However, if randomness exists in the universe, then information *can* be created. We can figure out the past based upon the present, but we cannot perfectly predict the future from the present.