TCS Daily


How Could the Consensus of Experts Be Wrong?

By Sallie Baliunas - July 22, 2004 12:00 AM

My colleagues are wrong, thought P, a famous physicist. So, too, are their lecture notes, exam problems, journal articles and textbooks, which have forwarded the bad ideas to students. They, in turn, would next engrave nonsense in the minds of their students.

P (we shall meet this physicist in a moment) had discovered over 100 years ago an important fact regarding the nature of light, which is a form of energy, and its interaction with matter. His work produced unforeseen and sweeping consequences. Yet, he later reflected:

"The effect of my dissertation on the physicists of those days was nil. None of my professors at the University had any understanding for its contents. ... I found no interest, let alone approval, even among the very physicists who were closely concerned with the topic."

How could the consensus of experts be wrong?

For many people -- even scientists -- it is easier to accept authority rather than labor to overturn an attractive idea, even though it is contradicted by unassailable experimental results. But those who make scientific discoveries reject ideas not grounded in experimental facts.

P recalled:

"It is one of the most painful experiences of my entire scientific life that I have but seldom -- in fact, I might say, never -- succeeded in gaining universal recognition for a new result. ... All my sound arguments fell on deaf ears. It was simply impossible to be heard against the authority of men like O, H and M."

The physicist, P, is the great Max Planck (1858 - 1947), who resolved a paradox about thermal energy emitted by heated matter.

According to 19th century classical physics, when an object is heated, the incident energy jostles the body's atoms and molecules, which absorb and then emit energy in a thermal radiation curve with a distinct peak wavelength dependent upon temperature.

The curves had been well measured, and physicists at the time had successfully explained the shift in the wavelength of peak of the radiated energy toward shorter wavelengths as an object was heated further and its temperature increased. Even the long-wavelength portion of the tail could be correctly described (as could the shorter-wavelength tail). But what couldn't be explained was the entire curve.

Classical physics also gave a disastrous interpretation of what would have to happen. The energy jostling among atoms and molecules would theoretically energize higher and higher frequencies, producing fierce ultraviolet, x-ray and gamma ray radiation.

Nature, though, does not exhibit this incinerating "ultraviolet catastrophe," as the paradox was called. Heated bodies, such as a human body or the hot coil on an electric range, do not emit dangerous amounts of x-rays and gamma rays.

The ultraviolet catastrophe arises because radiated energy from heated matter had been thought to occur through the action of waves. Classical physics allows energy to be shared among all wavelengths, including, preposterously, the very shortest and lethal gamma rays.

As later Nobel physicist Richard Feynman noted about the paradox:

"Of course we know this is false. ... ... Therefore, something is fundamentally, powerfully and absolutely wrong. Thus was the classical theory absolutely incapable of correctly describing the distribution of light from a blackbody...and there is no escape. This is the prediction of classical physics...and it is obviously absurd."

What did Planck discover? Planck could cast the observed results for heated matter in successful terms if he described the interaction of light and matter as occurring with discrete packets, or quanta, and not the infinitely subdivisible waves assumed in classical physics. The fundamental unit, or quantum, of light, is called the photon, and it cannot be subdivided further.

Planck's unorthodox results were announced on Dec. 14, 1900, and later prevailed as scientifically sound, in large part owing to the work published in 1905 by the ultimate skeptic, a young Swiss patent office examiner named Albert Einstein. But that is another story.

Planck agonized about his break with classical physics, "I can characterize the whole procedure as an act of despair, since, by nature, I am peaceable and opposed to doubtful adventures." Planck's willingness to allow facts to lead him, rather than prevailing opinion, ultimately secured for him the Nobel Prize in physics in 1918, and the honor of founding quantum physics, without which there would be no lasers, microscopic computers, or nuclear medicine to destroy cancers.

Planck's shattering of consensus so that knowledge could advance led him to comment on humans practicing science, "This experience gave me also an opportunity to learn a fact -- a remarkable one, in my opinion: A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up familiar with it."

Hence, next time the phrase "a consensus of scientists" is invoked regarding a scientifically complex matter, but unaccompanied by hard-won, reliable facts, demand evidence. It is the only way to know nature.

Notes and Good Reading

The initials of physical scientists stand for: P, Max Planck; B, Ludwig Boltzmann; H, Hermann von Helmholtz; K, Gustav Kirchoff; M, Ernst Mach; and O, Wilhelm Ostwald.

R. Feynman, R. Leighton and M. Sands, The Feynman Lectures on Physics, 1963, Addison-Wesley

Max Planck 1949, Scientific Autobiography and Other Papers


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