
Planck's Constant
h = 6.63 x 10^{34} Js =
0.000 000 000 000 000 000 000 000 000 000 000
663 Js 



Planck was surprised to discover
that the calculation became unmanageable if the lumps were
made infinitely small! He was forced to accept that 'h'
could not be zero but had to have a small, but definite,
value. Today, 'h' is referred to as the Planck constant
and has a value of about 6.63 x 10^{34} Js.
This has a profound consequence – it means that
the total energy of the vibrating system of oscillators
cannot be changed continuously but rather must change
in discrete steps (or 'quanta' – Latin for "how
much") dictated by the value of 'h'.
Planck had unveiled a completely new face of Nature!
On December 14, 1900 he presented his results to the Berlin
Physical Society, heralding the birth of quantum physics.
Planck was 42 years old. The idea was so bold and radical
that Planck himself was not totally convinced of its validity – he
worried that his quanta arose from a mathematical trick
and would one day be replaced by something better. In
fact, the idea lay fallow for many years while people
spent their time with the newly found phenomena of radioactivity
and xrays. Einstein eventually used the concept to explain
the photoelectric effect in 1905. Planck was eventually
awarded the Nobel Prize in Physics for his work in 1918. 