system
Given the following post, respond as if you're commenting on Reddit:
human
Why does vibration loosen machine thread fasteners as opposed to tightening them?

I understand vibration tends to loosen nuts and bolts.  Thus, the lock nut.  Why is it that vibration can only loosen a nut from a bolt?
gpt
The nut and bolt are slightly stretched when they are torqued. Vibration will allow them to relax which prevents the nut from re-torquing.

In addition, there are symmetry bolts with 2 sets of threads on them that are supposed to be vibration proof. They have a right handed course thread and a left handed fine thread, so you put a regular nut then a left handed jam nut and there you go.