MACH, ERNST

MACH, ERNST (1838–1916), Austrian physicist and philosopher.

Ernst Mach was born on 18 February 1838 into a German-speaking family with some Slavic roots, in Chirlitz/Chrlice in Moravia, in what is now part of the Czech Republic. He is best known as a critic of Newton and as the namesake for the terms "Mach One," "Mach Two," and so forth. Mach studied physics at the University of Vienna from 1855 to 1860 and taught that subject in Vienna (1861–1864), mathematics and later physics in Graz (1864–1867), and physics again in Prague (1867–1895).

Mach's experimental approach was based on an empiricism so narrow that it denied the reality of atoms and molecules. He applied the approach to problems in psychology and physiology as well as physics, and defended his phenomenalism on the grounds that it enabled him to work in both psychology and physics without having to change worldviews. In 1865, he discovered what are now called "Mach Bands" (that is, subjective color intensity on both sides of a boundary between two colors, which acts to make the boundary more conspicuous) and, in 1873, the equilibrium function of the inner ear. In the 1870s and 1880s he studied spark and ballistic shock waves. Possibly in reaction to the lack of attention paid before 1900 to this work, he seems to have turned to philosophy of science to help justify what some of his opponents considered an unduly narrow approach.

Mach became influential among physicists with the publication of his book Die Mechanik in ihrer Entwicklung (1883; The Science of Mechanics, 1893), which criticized Newton's theories of absolute space, time, and motion because they seemed to lack observable relations. He followed that work with his Beiträge zur Analyse der Empfindungen (1886; Contributions to the Analysis of the Sensations, 1897), which defended his rejection of a transconscious physical world in a way that he hoped would attract psychologists, physiologists, and philosophers.

Mach's new reputation made it possible for him to become the first professor in the history and philosophy of science in Vienna in 1895. However, three years later a stroke paralyzed the right side of his body, and he was forced to resign in 1901. He moved in 1913 to Vaterstetten, a village near Munich in Bavaria, where he died on 19 February 1916.

The first decade of the twentieth century saw both the highpoint of Mach's philosophical influence and criticism of the most severe kind against his phenomenalism and extreme form of positivism. His philosophical allies included William James, Karl Pearson, Wilhelm Ostwald, Otto Neurath, and other members of what would later be called the Vienna Circle who were associated with logical positivism, including Rudolf Carnap. But the most famous of his followers were Max Planck and Albert Einstein, who supported Mach's work in the 1890s.

Mach's opponents were numerous. Edmund Husserl accused him of "psychologism," or working from the premise that formal logic and mathematics had psychological roots. Vladimir Lenin (1870–1924) attacked him and positivists everywhere for denying the existence of the external physical world. In the 1910s, in light of Einstein's work on relativity and Jean-Baptiste Perrin's work on Brownian motion and the random movement of molecules, a more mature Max Planck argued that Mach's anti-atomism was detrimental to science. Conscious sensations may seem or may be subjectively certain, but physics was relying more and more on objective measurement of transconscious physical objects and processes using instruments and machines.

Mach was so offended by Planck's criticism that he threatened to "leave the church of physics" if belief in the reality of atoms were required. Einstein also criticized Mach for his position on the atomic theory, and it appears that Mach did in fact leave "the church" in 1913. A few months later Mach seems to have written the preface to his posthumously published book Die Prinzipien der physikalischen Optik (1921), in which he rejects Einstein's theory of relativity, which had included ideas from Mach.

Mach's criticism of Newtonian absolutes influenced Einstein's special theory of relativity (1905). Also, Einstein's general theory of relativity (1915) initially contained "Mach's Principle" that the totality of the stars have an influence on local inertia. But Einstein eventually dropped it, because it could not be deduced from the general theory. Starting in 1917 Einstein increasingly rejected Mach's epistemology, which he found too restrictive. Like Planck, Einstein often found it necessary in physics to make inferences beyond what could be sensed or made conscious. Nor could he accept Mach's notion that all theories were merely temporary.

In the late twentieth century, some philosophers traced some of Mach's views back to the psychological ideas of Johann Friedrich Herbart (1776–1841) and Ewald Hering (1834–1918). This view minimizes Mach's debt to the Irish philosopher George Berkeley (1685–1753), the German philospher Immanuel Kant (1724–1804), and epistemological idealism. It suggests that, rather than a phenomenalist or even a physicist, Mach was primarily a psychologist closer to direct realism, which held that external physical objects existed but could be directly sensed at least in principle. These philosophers also point out that Mach's emphasis on so-called mathematical functions as a substitute for laws and powers to relate sensory objects or impressions did not require the existence of space, which if true might help make it seem more plausible that distant stars could indeed influence local inertia in accord with Mach's Principle.

While there are few self-declared "Machists" in philosophy in the early twenty-first century, Mach's ideas live on in much of analytic philosophy and in some interpretations of physical theory. Indeed, many of his long minimized or overlooked experimental contributions to psychology, physiology, and physics show signs of becoming the best appreciated and least controversial aspects of his work.

See alsoEinstein, Albert; Husserl, Edmund; Physics; Planck, Max; Science and Technology.

bibliography

Banks, Erik C. Ernst Mach's World Elements. Dordrecht, Germany, 2003.

Blackmore, John T. Ernst Mach: His Life, Work, and Influence. Berkeley and Los Angeles, 1972.

——. Ernst Mach: A Deeper Look. Dordrecht, Germany, 1992.

Blackmore, J., R. Itagaki, and S. Tanaka, eds. Ernst Mach's Vienna, 1895–1930; or, Phenomenalism as Philosophy of Science. Dordrecht, Germany, 2001.

Hoffmann, Christoph, and Peter Berz, eds. Über Schall: Ernst Machs und Peter Salchers Geschoßfotografien. Göttingen, Germany, 2001.

Ratliff, Floyd, Mach Bands: Quantitative Studies on Neural Networks in the Retina. San Francisco, 1965.

John T. Blackmore