Planck’s Constant: The Number That Defines Quantum Physics

Planck’s constant is the tiny number that sets the scale of quantum physics.
It links a particle’s energy to the frequency of its wave: E = h × f.
Its value is about 6.626 × 10⁻³⁴ joule-seconds—astonishingly small.
Max Planck introduced it in 1900 to explain blackbody radiation.
Without it, the foundation of quantum mechanics wouldn’t exist.
It defines the “quantum,” the smallest possible packet of energy.
Planck’s constant sets the limit on how finely energy can be divided.
It appears in the uncertainty principle, wavefunctions, and quantum states.
In 2019, the kilogram was redefined based on Planck’s constant.
This single number bridges waves, particles, and the energy of the universe.