Ernst Mach – the great teacher of Albert Einstein

29. October 2019
He criticised Newton and rejected atomic theory, which he considered merely a product of theoretical physics. He recognized only things that could be proven in a practical experiment. Einstein wrote that “he should be seen as the precursor of the general theory of relativity”, and signed letters to him as “Your admiring student”.
Ernst Mach – the great teacher of Albert Einstein

Dear parents, your son is as sharp as a marble

Ernst Mach was born in 1838 in Chrlice u Brna, Moravia. A fragile child, he was educated at home until the age of 14. He only attended school for 2 years, at a Benedictine grammar school in Seitenstetten. He immediately showed some great talents, but he absolutely failed at classic languages education was based on at the time. In their evaluation, his teachers called him “unteachable, absolutely talentless”; now, with the benefit of hindsight, this looks like a common ritual every genius must endure when going through a classic institutionalized education system.

And Mach was a true genius indeed. He first made use of his great talents at university in Vienna, where he started his studies in 1855, excelling mainly in mathematics, physics, and philosophy. He finished his postgraduate studies in 1860, became an associate professor and started teaching there. It was at this time that he also began conducting his experiments.

"I know of nothing more terrible than the poor creatures who have learned too much. Instead of the sound powerful judgement which would probably have grown up if they had learned nothing, their thoughts creep timidly and hypnotically after words, principles and formulae, constantly along the same paths. What they are left with is a spider's web of thoughts too weak to furnish sure supports, but complicated enough to provide confusion."

What a range of activities!

It’s simply impossible to list all the things Mach was involved in during his scientific years. He considered himself a physicist, but was also a philosopher, even though he often mentioned that he felt “merely as a tenant” in philosophy. Mach influenced a large number of disciplines in an unparalleled way. His early research was related to visual and auditory perception and shockwaves caused by fast-flying projectiles. In experimental physics, he did research in interference, diffraction, polarisation, and refraction in various media. He explored the Doppler effect, made substantial achievements in psychophysics, especially the relation between the pressure in extraocular muscles and the perception of the form. He was in charge of studies on kinesthetic perception, which is the feeling related to movement and acceleration, and he discovered that the inner ear helps control balance. He also heavily promoted the use of photography in scientific experiments. 

Mach number is a physical quantity defining the ratio of the speed of movement of an object through an environment and the speed at which sounds spread in that same environment. It is frequently used in various technologies, e.g. as the ratio of the speed of flight to the speed of sound it is used to express the speed of flight in aviation. The first time an airplane flew faster than Mach 1 was in 1947. Currently, the top speed of a piloted airplane is Mach 6.7. A pro tip: if you see a jet plane and hear a roaring sound, it means that it has just reached supersonic speed in the given altitude, i.e. it has exceeded the speed of Mach 1.

His pedagogical activities were significant as well. He was a professor of experimental physics and then a rector at the university in Prague. Later, he became a professor of philosophy, mainly history and theory of inductive science at a university in Vienna. He also authored several high-school textbooks. It is certainly worth mentioning that he was the head of a physics institute at Prague University where the students – for the first time in its history – gained an opportunity to do scientific work. 

Mach the critic

Mach fiercely criticised Newton and had serious objections to Einstein’s work, specifically to his theory of relativity. And yet Einstein himself admitted how much he was influenced by Mach’s work. In a letter to Mach, Einstein says that it was especially Mach’s book on the development of mechanics that influenced him so much…

However, it was atomic theory Mach criticised the most. For Mach, the atom was a term that referred to something undefinable; something which complicates explanations of a number of phenomena. He felt that unproven ideas used for illustration were redundant and misleading. He claimed that all facts need to be based solely on direct perception. Facts were simply everything; no model ideas or even thinking about them were permitted. 

The Mach principle is a hypothesis claiming that the inertia of bodies is caused by the gravitational forces of mass around them, even at great distances. This idea substantially influenced Albert Einstein and his work on the general theory of relativity.
Many other terms were named after Mach, such as Mach’s wave machine or Mach bands. 

Fighting to the very end

Despite his huge popularity and prestige, his life was not without hardship. In 1898, he suffered a stroke which left half of his body paralyzed. He could still write, but had great difficulties lecturing. Heinrich, one of his sons, committed suicide at the age of 20. And Mach himself, towards the end of his life, had to face severe criticism from his colleagues, such as Max Planck and even Albert Einstein, his admirer from not so long ago. Mach spent the rest of his days adamantly defending his views.

Mach was an all-embracing, comprehensive, and vivacious personality of global science. He was renowned for his thoroughness, precision as well as manual skills, for his peacefulness and a clear, brief, and apt way of formulating his ideas. He was also a fierce opponent of fanatic nationalism and antisemitism. He refused the existence of God (and came to embrace atheism in his life) and Newton’s concept of absolute time and space. As a relativist, he declared that no scientific statement is acceptable unless empirically verifiable. Progress in atomic physics later showed how wrong he had been. Let’s quote his words here, though: “The errors of some people often have much more fruitful consequences than the discoveries of the others.”

Interesting facts

  • Mach was no bore. As a young man, he charmed Vienna as an excellent boxer and was by far the best fencer, which came as a surprise to those who had known him as a diffident, shy boy. 
  • Around 1862, Mach worked hard to improve the device to measure blood pressure, only to stumble on technological issues with implementation.
  • Asteroid No. 3949 is named after him.
  • A crater on the Moon has been named after him as well. However, it’s located on the dark side, so we cannot see it from the Earth.
  • The MACH3 razor was named after Ernst Mach as well. To be precise, its name refers to Mach number, and the “3” refers to its three blades, which allow for a 3x faster shave. At least that’s what Gillette says. :)

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