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Birthday
Mach was born in Moravia on Feb 18, 1838. In 1840 his family moved to a farm in Untersiebenbrunn, Lower Austria. -
Doppler Theory
Mach’s first important scientific contribution was over the recently discovered ‘Doppler theory’. In 1841, Christian Doppler noticed that sound changes in frequency as a source moves toward and away from an observer. -
Education
He studied physics at the University of Vienna from 1855 to 1861, continuing on as a lecturer until 1864. After spending three years as Professor of Mathematics at Graz, he received a Chair at Prague where he stayed until 1895. For the next six years, Mach occupied a Chair in the History and Philosophy of the Inductive Sciences at Vienna. He suffered a stroke in 1898 and retired in 1901. He died near Munich in 1916. -
Mach Bands
In 1865 Mach published, “On the effect of the spatial distribution of the light stimulus on the retina,” the first of a series of remarkable articles on what are now known today as Mach Bands. -
Mach Bands
The thin dark bands along the outer edges of the gradients and the thin light bands along the inner edges of the gradients are optical illusions. The cause of this effect is due to contrast perception; we over process at boundaries and under process where there is constancy. In fact sensory response can even stop with unchanging stimulation. Mach is credited for discovering lateral inhibition in our sense organs, the idea that our senses pre-process information before sending it to the brain. -
Shockwaves
In the late 1860s developments in gun and artillery technology produced projectiles that traveled faster than sound vibrations. This was realized over a period of time as two effects were investigated—a second loud ‘boom’, distinct from the usual one of the explosion, as well as a different type of wound. It was the latter that began Mach’s interest. -
Supersonic Motions
By 1885 Mach had worked out the details of supersonic motion, along the way developing high-speed photographic techniques. Most importantly for engineers, Mach Number is the ratio of the speed of the object to the speed of sound in the given medium; his work is essential to modern aerodynamics, and through it the word ‘Mach’ has bizarrely entered into popular culture as an icon for razors, sound systems, fighter pilots, and high speed fuels. -
Gestalt Theory
The seminal article of Gestalt Theory begins with a review of these ideas, found in Mach’s 1886 Analysis of Sensations. Sensations are not simply raw experiences, but the interaction of experience with a pre-formed cognitive structure. For instance, when we hear a known melody, we recognize it no matter what key it is played in. It can be hummed, buzzed, or strummed on a guitar. Furthermore, even if one or more notes are incorrect, we still recognize it. -
Speed and Sound
Mach’s name is, of course, associated with the speed of sound, where Mach 1 means the speed of sound in a given medium. The Mach number is named after Moravian physicist and philosopher Ernst Mach, and is a designation proposed by aeronautical engineer Jakob Ackeret in 1929. -
Short educational Video