The picometre is a unit of length and is a multiple of the SI unit metre. It uses the symbol pm.
It represents one trillionth of a metre, or one hundredth of an Ångström.
Because the picometre is so small, its use is restricted almost entirely to chemistry, quantum physics and particle physics. Atoms are typically 62 pm and 520 pm.
LISA (Laser Interferometer Space Antenna) is a probe planned for launch in 2034 to detect gravitational waves in space. Its measures these displacements with an accuracy of up to 20 pm over a distance of 2,500,000,000 m.
The mile is a unit of length in the imperial unit system with the symbol mi.
It was originally an English unit but was adopted by many countries who all had their own slight variation on definition. The English mile, however, is equal to 63,360 inches, 5280 ft or 1760 yards.
The UK still uses the mile on all roadway signs rather than the kilometre; its SI "equivalent". It used to have the symbol 'm' until SI was established and it was changed to avoid confusion with the unit metre.