system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it that when metal conductors are cooled they have lower resistance? Can you lower resistance by increasing pressure as well?

What is going on at the molecular&/subatomic  levels that makes this possible? Thanks!
gpt
For a metal, reducing the temperature reduces the kinetic energy of the ions in the giant metallic lattice (hence they get colder). 

The ions in the lattice are always vibrating, and their vibration is directly proportional their kinetic energy. Therefore, as the temperature lowers the lattice vibrates less. 

This means an electron can move through the lattice (a current flowing) more easily, that is to say it's movement will not be impeded by the lattice as much. Therefore more electrons can flow through the lattice, so for the same potential difference the current increases, so the resistance must drop.

*Bare in mind for other conductors, where the free ions are not as a result of metallic bonds  (like semiconductors) decreasing the temperature has the opposite effect - it increases their resistance. This is because the free ions have less energy, so less kinetic energy (in this case the lattice does not vibrate, as covalent bonds join adjacent atoms, usually silicon, rather than metallic bonds), so are less likely to move in the structure.* **Better/correct explanation below.**