Heinrich Hertz (1857-1894)
The electromagnetic spectrum, and its commercial exploitation, today seems as commonplace as the air that surrounds us. And yet, there was a time, in the not too distant past, when the very concept of the electromagnetic spectrum was unknown. In the 1860s, in a series of papers, James Clerk Maxwell first laid out his theory of the electromagnetic field. Then, in 1873, Maxwell produced his well-known, two-volume Treatise on Electricity and Magnetism. Far from being an instant success, it took almost two decades before “Maxwell’s Laws” gained widespread acceptance within the scientific and engineering establishments. The key that unlocked the door to universal acceptance was Heinrich Hertz. His elegant experiments transformed contested theory into an accepted model of reality. On the 150th anniversary of Hertz’s birth, it is fitting that we reflect briefly upon the man, and his role in setting the stage for the profound technological applications that would emerge from the electromagnetic field concept.
When Hertz began his experiments on electrodynamics in 1886, little was known about Maxwell’s ideas on the continent of Europe, where Newtonian action-at-a-distance was still the only paradigm for understanding electrical and magnetic phenomena. By the end of the decade, Hertz’s validation of Maxwell’s electromagnetic field theory had forced a conceptual revolution within the European community of theoretical physicists. Hertz had shown that rather than being instantaneous, electromagnetic effects propagated at a finite speed. An even more astounding result from Hertz’s experiments was the discovery of radio waves and the realization that they behaved like light. In Maxwell’s homeland, the British Isles, the impact of Hertz’s experiments was equally dramatic, but opposition was from a different quarter.
Unlike the situation in continental Europe, Maxwell’s work in electricity and magnetism developed a very strong following among the theoretical physicists on the western side of the Channel. Maxwell himself had not actively sought to create a school around his theory. But a small number of theoreticians scattered throughout Britain and Ireland were immediately taken by Maxwell’s reconceptualization of electricity and magnetism. Men like George Fitzgerald, Oliver Heaviside, Oliver Lodge, William Thomson, John Poynting and Silvanus Thompson took it upon themselves to refine, expand on, and champion Maxwell’s theory. Thus, before Hertz even started his experiments on electrodynamics, Maxwell’s theory had already gained a strong theoretical foothold in the British Isles. But not all in Britain accepted Maxwell’s notions. Most electrical engineers were very mistrustful of Maxwell’s theory of electrodynamics. Like Edison and the others who had developed electrical technology to this point, they saw themselves as “practical men” and they could not see any value in the complex, mathematical theories advanced by the Maxwellians. In the eyes of these practical men, the Maxwellians were more interested in abstract formalism than in hard reality. Sir William Preece exemplified the “practical” man’s disdain of theory.
As one of the most prominent electricians of the day, William Preece held considerable sway in the halls of industry and government. Preece had not had any formal training in electricity and magnetism when he joined the Electric Telegraph Co. Learning by doing, he rose up in the company. When the British government put all telegraphy under the control of the Post Office, Preece was named its Chief Electrician. Bruce Hunt, an historian of Physics, reminds us that Preece, like many of his countrymen of the day, was deeply mistrustful of theoretical abstractions. Experience, not theory, was the key to teasing out the technological opportunities in nature. Born in 1834, fifteen years before most of the Maxwellians, Preece saw these theoreticians as young upstarts who had little respect for the experience acquired by their elders. The scientific and technical arguments between Preece and the Maxwellians were often acrimonious. There was disdain on both sides.
The Maxwellians greeted the news of Hertz’s experiments with great jubilation. Having put their theoretical abstractions on the bedrock of reality, Hertz’s results undercut the central objection raised by practical men like Preece. The Maxwellians had themselves looked for empirical evidence but were unsuccessful. So it is ironic that the prize would go to a man from Europe where Maxwell’s ideas were relatively unknown. The generational debate between Britain’s older practical electrical engineers and its younger theoretical physicists would soon end. Not necessarily because the older generation acquiesced, but rather because they died off and were eventually replaced by the first generation of academically trained electrical engineers who were now well-versed in Maxwell’s mathematical theory.
By the early 1890s, Hertz’s work had won universal acclaim. Then in his mid-thirties, with a brilliant future and fame assured, Hertz had to face death. In 1892, he was diagnosed with a head cold and then with an allergy, his condition progressively deteriorated. His body had been invaded by stubborn infections. Then he succumbed to blood poisoning. For nearly two years, he suffered through debilitating poor health. His spirits must have been very low and yet he always remained a playful father with his children. Fearing that the end was near, he was determined to finish his treatise on mechanics. He faced death with courage, humility and a sense of duty. “Nothing is harder,” he wrote, “than a struggle fought no longer for victory, but merely so as not to give up without making a decent stand.” There was also a calm acceptance. Three weeks before his death on 1 January 1894, he wrote to his parents:
“If anything should befall me, you are not to mourn; rather, you must be a little proud and consider that I among the especially elect destined to live for only a short time and yet to live enough. I did not desire or choose this fate, but since it has overtaken me, I must be content; and if the choice had been left to me, perhaps I should have chosen it myself.”
Mathilde Hertz and Charles Susskind (eds.), Heinrich Hertz: Erinnerungeon, Briefe, Tagebücher/ Memoirs, Letters, Diaries (second enlarged bilingual edition), (San Francisco: San Francisco Press, 1977)
J.G. O’Hara and W. Pricha, Hertz and the Maxwellians, (London: Peter Peregrinus Ltd. And Science Museum of London, 1987)
Bruce J. Hunt, The Maxwellians, (Ithaca, NY: Cornell University Press, 1991)
Jed Buchwald, Creation of Scientific Effects: Heinrich Hertz and Electric Waves, (Chicago: University of Chicago Press, 1994)
Charles Susskind, Heinrich Hertz: A Short Life, (San Francisco: San Francisco Press, 1995)