Born Wittenberg, (Germany), 30 November 1756
Ernst Chladni contributed significantly to the founding of modern meteoritics. He was the only child of Ernst Martin and Johanna Sophia Chladni. The family was originally from Kremnitz (Kremnica), Slovakia. Chladni’s grandfather and father were both professors of jurisprudence at Wittenberg. He never married.
Although he was educated by his parents in a strict, rather isolated household, Chladni developed a yearning for travel and a strong interest in the natural history of the Earth and the heavens. On his father’s bidding, Chladni studied law and philosophy at Wittenberg and Leipzig, where he earned his doctorate in 1782. His father died shortly afterward, leaving him free to pursue his own interests.
Chladni mastered mathematics and physics and conducted his earliest experiments on the vibrations of solid plates and the velocity of sound waves in various gases. He also designed and built two keyboard musical instruments, the euphonium and the clavicylinder. In 1787, Chladni published a highly influential book on the theory of sound waves for which he became known as the “father of acoustics.” He then began a lifetime of traveling, giving lectures and demonstrations, first on acoustics and later on meteorites, between periods of working and writing at home in Wittenberg.
In the early 1790s, Chladni’s became interested in the nature of fireballs. He questioned whether they form around solid bodies as they plunge through the atmosphere or consist entirely of gases. Chladni spent 3 weeks at the library in Göttingen where he discovered that eyewitnesses in different centuries and in widely spaced localities had given remarkably similar accounts in sworn testimony to the appearances of brilliant fireballs accompanied by thunderous explosions and followed by the fall of stones or fragments of iron out of the sky.
Contemporary scholars viewed the idea of rocks from the sky as vulgar superstition. But Chladni selected the 18 most detailed fireball reports from those dating between 1676 and 1783 and compared their apparent beginning and end points, magnitudes, velocities, and the number and force of their explosions. His results were so consistent, and the eyewitness testimony so convincing to his lawyer’s ear, that Chladni concluded that solid bodies falling from fireballs are authentic natural phenomena.
Other scientists explained fireballs as atmospheric phenomena, related in some way to either electricity, the zodiacal light, the aurora, or to streaks of inflammable gases in the sky. Noting that fireball velocities greatly exceeded those attributable to gravity, Chladni perceived that they could not originate in the atmosphere but must enter the upper atmosphere from space and then heat to incandescence as they decelerate due to friction with the air. He explained meteors the same way except that he believed that these small bodies pass through the atmosphere and reenter space instead of burning up. Chladni proposed that the incoming bodies are small masses of primordial matter that formed in deep space and never accumulated into planets, or are the debris of planets that have been destroyed by internal explosions or by collisions in space.
In comparing descriptions of the allegedly fallen stones, Chladni found that they all had thin black crusts wholly or partially covering gray interiors sprinkled with small grains of shiny metal. At least one body, observed to fall from a fireball in 1751 at Hraschina in Croatia, was a 71-lb mass of metallic iron. Chladni reasoned that if this piece of metal fell from the sky, so did two other isolated iron masses, one of which had been found in the remote chacos of northern Argentina, the other on a mountainside in Siberia. Each of these lay far from volcanoes or any mining or smelting operations. The Siberian iron had been shipped to Saint Petersburg by Peter Simon Pallas. It consisted of metallic iron studded with large, translucent yellow crystals, which Chladni correctly surmised were olivine. Similar meteorites came to be called pallasites.
In 1794, before he ever examined a meteorite, Chladni published a small book, Über der Ursprung der von Pallas Gefundenen und anderer ihr ähnlicher Eisenmassen, und Über Einige Damit in Verbindung stehende Naturerscheinungen, in which he compiled all his data, demolished other hypotheses case by case, and presented his conclusions: (1) solid bodies of stone and iron do, in fact, fall from the sky; (2) they form fireballs as they plunge through the atmosphere; and (3) they originate in space. This was the first scholarly book on meteorites, and it applied the principles of physics to them. Although Chladni made some serious errors in it, his basic conclusions were sound. Nevertheless, his book was not well received. Scholars refused to trust the testimony of uneducated people and responded to reports of fallen bodies by identifying the specimens as ordinary rocks struck by lightning, fragments hurled from distant volcanoes, or masses coagulated from dust in the atmosphere – a process that had been suggested in 1789 by the chemist Antoine-Laurent de Lavoisier. More seriously, Chladni’s book violated some of the deepest-held convictions about the nature of the Universe. Chladni’s hypothesis that small bodies originate in space ran counter to Isaac Newton’s dictum of 1704 that to assure the regular and lasting motions of his clockwork Solar System, based on his laws of universal gravitation, all space beyond the Moon must be empty.
Between 1794 and 1798, falls of stone occurred in Italy, England, Portugal, and India. These events prompted Sir Joseph Banks, the president of the Royal Society in London, to ask chemist Edward C. Howard to analyze some of the stones. Howard, working with the mineralogist Jacques-Louis de Bournon, analyzed four fallen stones and four suspected fragments of fallen iron. He made the totally unexpected discovery that the irons and the metal grains in the stones all contained several percent of nickel. This linked irons with stones and set both apart from common rocks of the Earth’s crust. From this work, published in 1802, in which Howard referred to Chladni’s book, meteoritics emerged as a new branch of science.
Chladni’s theory of fireballs soon gained acceptance, and he received full credit for it. He obtained specimens for study and published numerous papers on them plus one more book, in which he summarized all that was known about meteorites in 1819. Ultimately, Chladni acquired the largest private meteorite collection of the early nineteenth century and willed it to the University of Berlin where his specimens are on display. Still, Chladni’s theory of the origin of meteorites in space gained little support until the 1860s. Today we accept his suggestion that meteorites are debris from collisions in space. Most of them are fragments of asteroids, and a few result from asteroidal impacts on the Moon and Mars.