In 1900, Planck discovered a relationship between the
energy and frequency of light: E = hv. The equation
had revolutionary implications, but it took years for anyone to
realize it. And when someone finally did stumble upon the true
meaning of Planck's theory, it was not Planck, but another promising
young German physicist: Albert Einstein.
In 1905, the young Einstein was working as a technical
expert in a Swiss patent office, and he was also engaged in formulating
a series of new theories that would transform twentieth century
physics. That year he published three papers that would establish
him as one of the foremost physicists of the new century. One of
the papers addressed Brownian motion, the random motion of particles
suspended in a liquid. One of the papers, his most famous, introduced the
theory of special relativity, the theory that would elevate him
to international fame. But when Einstein received his Nobel prize,
it was not awarded for the ideas put forward in this paper. He received
this highest honor for the theory propounded in the third paper
of 1905: "Concerning a Heuristic Point of View about the Creation
and Transformation of Light." In this paper, Einstein revealed the
implications of Planck's equation, and he threw the order of classical
physics into chaos.
The equation E = hv necessitated that
light energy came in finite packets, or quanta, which directly
contradicted everything scientists had previously believed. According
to classical physics, light is a continuous wave – not a finite
particle. Planck, and those who followed him, had taken this contradiction
in stride by refusing to acknowledge it. The equation was nothing
more than a mathematical construct, something with no manifestation
in reality. But Einstein argued that this equation described reality
and that despite all evidence to the contrary, light was in fact
emitted and absorbed in finite packets, as if it were a particle.
This new understanding of light as quanta, and the new
light it shed on questions of the interaction between energy and
matter, was eagerly taken up by at least a few bright physicists.
Quantum Physics, as it came to be called, soon became the most
exciting and influential field of twentieth century physics, and
the new quantum physicists were quick to acknowledge the debt they
owed to the father of their new discipline, Max Planck.
Planck was less than eager to accept the title. A staunch
supporter of classical physics and a devout believer in light as
a continuous wave, Planck was reluctant to accept what his own
theory told him. As his colleague James Franck later remembered,
Planck "was a revolutionary against his own will."
In 1911, Einstein and some of his colleagues convinced
Planck that it was time to hold a conference on the issue of radiation
and quanta to finally discuss as a group the startling new problems
of quantum physics. Planck was skeptical, but he eventually agreed. That
year, twenty-one of the best European physicists, theorists, and
experimentalists, met in Brussels for the first Solvay Conference on
quantum physics. Although the conference failed to produce any solutions
to the problems facing these scientists, it was a chance for them
to define themselves as practitioners of a new discipline. It was also
a chance for Planck to witness the materialization of a new scientific
field for which he was partly to thank.
