system
Given the following post, respond as if you're commenting on Reddit:
human
When a solid is broken, why don't the atoms re-bond when pressed back together?

Say you have a gold brick. I get that this is basically a mesh of many atoms, all of which have the same amount of protons, neutrons, etc, and that these atoms all bond with each other. Now say you split it cleanly in half. If you press it back together, what is stopping the atoms from re-bonding back to the original state?
gpt
Oxide layers rapidly form when the surfaces are exposed to air, and macro/microscopic contaminants (including air itself) get trapped between the surfaces when you press them back together, preventing the bonds from reforming. Not to mention that whatever method you use for cutting the material probably didn't leave a microscopically smooth surface, meaning that the only pieces in contact unless you apply a lot of clamping force will be the small hills sticking out from the surface.

But your instinct is right -- this is possible with clean cuts in a vacuum.