system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Snapple cap real fact # 1003 - If two pieces of the same type of metal touch in outer space, they will bond together permanently.
gpt
It's called cold welding. The premise is that when two *unoxidized* pieces of metal contact each other in a vacuum they bond to each other because the atoms have no way of 'knowing' that they're two separate pieces. It's a problem that's taken into account when designing space vehicles.