Today, the prince and the blurred pea. The University of Houston's College of Engineering
presents this series about the machines that make our civilization
run, and the people whose ingenuity created them.
Quantum physics was formulated during the first three decades
of the 20th century. First, Max Planck predicted the way radiant energy varied with
wavelength, from very short cosmic rays through X-rays, ultraviolet, visible, infrared,
heat, microwave, and radio waves. He succeeded by parceling energy into tiny packets.
That bizarre idea met resistance. But then Einstein used it to predict additional
behavior -- so did others. Finally, Heisenberg gave us the Uncertainty Principle,
and Schrodinger his famous equation, which encompassed all these strange results.
Nature itself shifted upon its axis, and we took up residence in a new quantum world.
But the key link between Plancck's tiny quantum energy packets and the quantum physics
in place by 1930, was a very strange idea. And it was put forth by a French prince.
He was Louis de Broglie (whose name the French pronounce more like de Broy.)
He was born in Dieppe, in 1891 -- youngest son of the fifth duke de Broglie. His
older brother Maurice became the sixth duke and, when Maurice died in 1960, Louis became
the seventh -- until his own death, at almost 95.
De Broglie was raised as a prince. He was educated at home by tutors, then finished
a university course in math and philosophy at the age of 17. Maurice, by the way,
was an experimental physicist, but Louis always tilted more strongly toward theoretical
Before WW-I, Louis de Broglie was doing graduate work in law at the Sorbonne, and spending
a lot time reading current work in physics. He'd been floundering, and now was drafted
into the army. He began in mine removal, then transferred to radiotelegraphy.
When he got out six years later, he had direction. He plunged into quantum theory
and, in 1922, wrote a doctoral thesis in which he set forth a new principle: That
all bodies have a wavelength associated with them. That wavelength is Planck's constant
divided by the body's momentum. Your wavelength or mine is immeasurably small. That's
because Planck's constant is tiny and we're so large. But what about a pea -- at
least a figurative pea?
The wavelength for a tiny electron is much larger than the electron itself. On the
micro-scale, objects are smeared out in space. By 1924, Prince de Broglie's Principle
was fully formulated. Three years later it was confirmed experimentally; and, in
1929, de Broglie won the Nobel Prize.
He went on to teach at the University of Paris, then became secretary of the Académie
of Sciences. Few scientists were ever as unremittingly cheerful and well-loved as de
Broglie. In 1952 he won the first Kalinga Prize for his work in popularizing science.
But what he'd really done was to build the bridge between quanta as simple packets of
energy, and the new quantum physics of matter blurred and smeared. This prince truly
did reshape the very pea that so troubled the sleep of scientists, a century ago.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
I. James, Remarkable Physicists. (Cambridge, UK: Cambridge University
Press, 2004): see From de Broglie to Fermi, pp. 305-315.
C. L. Tien and J. H. Lienhard, Statistical Thermodynamics. (New York:
Taylor and Francis, 1979/1971): Ch. 4, Development of Quantum Mechanics.
See also the Wikipedia article on de Broglie, from which the photo of de Broglie above is taken.
If is not familiar, here is the story of
The Princess an the Pea.
Edmund Dulac's art nouveau illustration of Han Christian Andersen's story of The Princess and the Pea,
The Engines of Our Ingenuity is
Copyright © 1988-2006 by John H.