Ernst Mach made major contributions to the fields of physics, philosophy and physiological psychology. The speed of sound still bears his name as he was the first physicist to systematically study super-sonic motion. He also made important contributions to understanding the Doppler effect. Mach’s critique of Newton’s ideas of absolute space and time were an inspiration to the young Albert Einstein, who credited Mach as being the philosophical forerunner of relativity theory, while his systematic skepticism of the old physics was similarly important to a generation of young physicists.
Academic Career
Ernst Mach was born in Chirlitz in Austria in1838. His father was tutor to a noble family and, up until the age of 14 when he enrolled at a Gymnasium in Kremsier, Mach was educated at home by his parents. In 1855 Mach entered the University of Vienna where he studied physics, his early work focusing on the Doppler effect in optics and acoustics.
In 1864 Mach was appointed as a Professor of Mathematics in Graz, having turned down the position of Chair of Surgery at the University of Salzburg to do so, and in 1866 he was appointed as Professor of Physics. During this period Mach continued his work on psycho-physics and sensory perception. In 1867 he was appointed Professor of Experimental Physics at Charles-Ferdinand University in Prague.
In 1898 Mach suffered a stroke and in 1901 he retired from his position at the University to take up an appointment in the Upper Chamber of the Austrian parliament. Mach retired from public life in 1913 but continued to writing and corresponding until his death in 1916.
Physics
Mach’s main contribution to the study of physics was his description and photographs of spark shock waves and then ballistic shock waves. It was Mach who described how passing the sound barrier compressed the air in front of bullets and shells. The ration of the speed of a projectile to the speed of sound is now known as the Mach number.
Most of Mach’s studies in the field of experimental physics were devoted to interference, diffraction, polarization and refraction of light in different media under external influences. These studies were followed by his important investigations in the field of supersonic velocity.
Mach also contributed to the study of physical cosmology with his hypothesis of Mach’s Principle, the idea that motion ultimately depends on the distribution of matter, or its mass, not on the properties of space.
Philosophy of Science
Mach is also known for his philosophy, a kind of phenomenalism that recognised only sensations as real. Mach held that scientific laws are summaries of experimental events, constructed for the purpose of human comprehension of complex data. He thus believed that scientific laws have more to do with describing sensations than with reality as it exists beyond sensations.
This belief was incompatible with the idea that atoms and molecules were external, mind-independent things and from 1908 to 1911 Mach’s reluctance to acknowledge the existence of atoms was criticised as being incompatible with modern physics.
Mach perceived scientific theories as being only provisional and having no lasting place in physics. Much to the disappointment of Albert Einstein, this belief made it next to impossible for Mach to accept Einstein’s special theory of relativity.
Psychology
In his study of psychology, Mach worked chiefly in the field of sensory perception where he is best known for the optical illusion known as the Mach band. Mach bands are formed from an image of two wide bands, one light and one dark, separated by a narrow strip with a light-to-dark gradient. The human eye perceives two narrow bands of different brightness either side of the gradient that are not present in the actual image.
Sources:
Blackmore, John (1992) Ernst Mach: His Life, Work and Influence (Los Angeles: Berkley)
Dawkins, Richard & Kerrod, Robin (2001) Oxford Illustrated Science Encyclopedia (OUP Oxford)
