system
Given the following post, respond as if you're commenting on Reddit:
human
Why does paper stay folded once you fold or wrinkle it? And since placing heavy objects on paper can help smooth it out, how much force would you have to apply to a creased sheet of paper to make it completely "smooth" again?
gpt
Imagine what paper looks like on a microscopic level. It's basically a bunch of cellulose fibers woven together. For the purposes of argument, let's imagine we have a gigantic piece of paper, and instead of fibers, we have sticks. 

When you fold that giant paper, some of the sticks at the fold point are going to break. The harder you fold, the more sticks break. Not all of the sticks break; some bend, enough that the paper can stay intact. Even if you straighten out the giant paper though, some sticks remain broken. 

This is what happens when you fold paper. You are actually weakening the structural integrity of the paper. You make breaks in some of the fibers, we while some just bend or twist. The ones that break are permanently broken.