Max Planck quantum mechanics |

## Planck constant

The energy of a phonon
is related to its frequency
by the Planck constant, *h,*
as *E* = *hf.*
Max Planck calculated *h*
to explain the nature
of black-body
radiation,
but in 1900
Planck realized that *h*
was the smallest unit
of *action*—
the basis of everything,
not just photons,
but all energy
and all matter.

## Planck units

A natural unit of measurement
is based on a property of nature.
A property of nature like
the least largest unit of motion.
The dimensions of motion
are energy and time,
and its value can be expressed
in joule-seconds, or in Plancks.
Fundamental units
for mass, length, and time,
therefore, for all physical quantities,
can be expressed in terms of
*ħ,* the reduced Planck’s constant,
*G _{0},* Newton’s gravitational constant,

*k*Coulomb’s constant for electric force,

_{e},*k*Boltzmann’s constant for kinetic energy, and

_{B},*c,*the velocity of light. These, with clever arrangements of powers and roots, give us natural units for Planck length, Planck mass, Planck time, Planck charge, and Planck temperature.

## Gyroscope

Even an imperfect gyroscope maintains its vertical to conserve angular momentum. If you could harness a perfect gyroscope, it could turn the hand of a clock once every day, but the harness would impair the gyroscope so that it would thus be imperfect.

The Planck constant led directly to the discovery that nothing in the physical universe is strictly continuous; instead, everything is quantized. The Planck constant reduced by dividing by 2π (ħ or h-bar) is the quantum of angular momentum (the smallest possible piece of orbital or rotating energy) and helps determine the sizes of the Bohr magneton and other neat little units of our universe.

See also in

The book of science:Stefan-Boltzmann law—Josef Stefan, Ludwig BoltzmannQuanta—Max Planck, Albert EinsteinDisappearing-filament pyrometer—Ferdinand Kurlbaum, Ludwig Holborn, Harmon Northrup MorseAtom—Ernest Rutherford, Niels BohrBohr magneton—Niels BohrUncertainty principle—Werner HeisenbergDirac equation—Paul DiracHawking radiation—Stephen HawkingReadings in wikipedia: