A single atom can gauge teensy electromagnetic forces
The unit of measure, a zeptonewton, is equal to one billionth of a trillionth of a newton

FEEBLE FORCE Scientists detected a tiny force using a charged atom (illustrated as a red sphere), which moved (orange) when pelted with laser light (purple). A lens focused light emitted from the atom into a moving image (black arrow).
V. Blūms et al/Science Advances 2018