the universe's fine print, where particles refuse to pick a lane until you make them.
means physical phenomena that only show up at very small scales, where matter behaves like probability clouds instead of tidy little billiard balls.
from early 1900s physicists like planck and einstein noticed energy comes in discrete chunks, not smooth streams, forcing a total rewrite of classical physics into quantum mechanics.
double slit experiment — light acts as wave and particle depending on observation, since 1801, reinterpreted 1927.
quantum tunneling in stars — lets the sun fuse hydrogen despite not being hot enough, classically.
transistors — rely on quantum tunneling, powering every phone and laptop made.
mri machines — use nuclear spin, a purely quantum property, to image bodies.