# Ernst Mach

Ernst Waldfried Josef Wenzel Mach (/ˈmɑːx/; German: [ˈɛɐ̯nst max]; 18 February 1838 – 19 February 1916) was an Austrian[7] physicist and philosopher, noted for his contributions to physics such as study of shock waves. The ratio of one's speed to that of sound is named the Mach number in his honor. As a philosopher of science, he was a major influence on logical positivism and American pragmatism.[8] Through his criticism of Newton's theories of space and time, he foreshadowed Einstein's theory of relativity.

Ernst Mach
Ernst Mach (1838–1916)
Born
Ernst Waldfried Josef Wenzel Mach

18 February 1838
Brno, Moravia, Austrian Empire (present day Czech republic)
Died19 February 1916 (aged 78)
ResidenceAustrian Empire, German Empire
NationalityAustrian
CitizenshipAustrian
Alma materUniversity of Vienna
Known forMach number
Mach's principle
Shock waves
Mach waves
Mach reflection effects
Mach band
Criticism of Isaac Newton's bucket argument[1]
Mach diamonds
Empirio-criticism
Relationism
Scientific career
FieldsPhysicist
InstitutionsUniversity of Graz
Charles University (Prague)
University of Vienna
Doctoral studentsHeinrich Gomperz
Ottokar Tumlirz
Other notable studentsAndrija Mohorovičić
InfluencesAndreas von Ettingshausen[2]
Gustav Fechner[3]
Carl Ludwig[4]
InfluencedVienna Circle
Russian Machism
Ludwig Boltzmann
Albert Einstein
Wolfgang Pauli
William James
Wilhelm Kienzl[5]
Pierre Duhem[6]
Signature
Notes
He was the godfather of Wolfgang Pauli. The Mach–Zehnder interferometer is named after his son Ludwig Mach, who was also a physicist.

## Biography

Ernst Waldfried Josef Wenzel Mach was born in Chrlice (German: Chirlitz), Moravia (then in the Austrian Empire, now part of Brno in the Czech Republic). His father, who had graduated from Charles University in Prague, acted as tutor to the noble Brethon family in Zlín in eastern Moravia. His grandfather, Wenzl Lanhaus, an administrator of the Chirlitz estate, was also master builder of the streets there. His activities in that field later influenced the theoretical work of Ernst Mach. Some sources give Mach's birthplace as Tuřany (German: Turas, now also part of Brno), the site of the Chirlitz registry-office. It was there that Ernst Mach was baptized by Peregrin Weiss. Mach later became a socialist and an atheist.[9] His theory and life, though, was sometimes compared with Buddhism, namely by Heinrich Gomperz who addressed Mach as the "Buddha of Science" due to the phenomenalist approach of the "Ego" in his Analysis of Sensations.[10][11]

Up to the age of 14, Mach received his education at home from his parents. He then entered a Gymnasium in Kroměříž (German: Kremsier), where he studied for three years. In 1855 he became a student at the University of Vienna. There he studied physics and for one semester medical physiology, receiving his doctorate in physics in 1860 under Andreas von Ettingshausen with a thesis titled "Über elektrische Ladungen und Induktion", and his habilitation the following year. His early work focused on the Doppler effect in optics and acoustics. In 1864 he took a job as Professor of Mathematics at the University of Graz, having turned down the position of a chair in surgery at the University of Salzburg to do so, and in 1866 he was appointed as Professor of Physics. During that period, Mach continued his work in psycho-physics and in sensory perception. In 1867, he took the chair of Experimental Physics at the Charles University, Prague, where he stayed for 28 years before returning to Vienna.

Mach's main contribution to physics involved his description and photographs of spark shock-waves and then ballistic shock-waves. He described how when a bullet or shell moved faster than the speed of sound, it created a compression of air in front of it. Using schlieren photography, he and his son Ludwig were able to photograph the shadows of the invisible shock waves. During the early 1890s Ludwig was able to invent an interferometer which allowed for much clearer photographs. But Mach also made many contributions to psychology and physiology, including his anticipation of gestalt phenomena, his discovery of the oblique effect and of Mach bands, an inhibition-influenced type of visual illusion, and especially his discovery of a non-acoustic function of the inner ear which helps control human balance.

One of the best-known of Mach's ideas is the so-called "Mach principle," concerning the physical origin of inertia. This was never written down by Mach, but was given a graphic verbal form, attributed by Philipp Frank to Mach himself, as, "When the subway jerks, it's the fixed stars that throw you down."

Ernst Mach's historic 1887 photograph (shadowgraph) of a bow shockwave around a supersonic bullet[12]

Mach also became well known for his philosophy developed in close interplay with his science.[13] Mach defended a type of phenomenalism recognizing only sensations as real. This position seemed incompatible with the view of atoms and molecules as external, mind-independent things. He famously declared, after an 1897 lecture by Ludwig Boltzmann at the Imperial Academy of Science in Vienna: "I don't believe that atoms exist!"[14] From about 1908 to 1911 Mach's reluctance to acknowledge the reality of atoms was criticized by Max Planck as being incompatible with physics. Einstein's 1905 demonstration that the statistical fluctuations of atoms allowed measurement of their existence without direct individuated sensory evidence marked a turning point in the acceptance of atomic theory. Some of Mach's criticisms of Newton's position on space and time influenced Einstein, but later Einstein realized that Mach was basically opposed to Newton's philosophy and concluded that his physical criticism was not sound.

In 1898 Mach suffered from cardiac arrest and in 1901 retired from the University of Vienna and was appointed to the upper chamber of the Austrian parliament. On leaving Vienna in 1913 he moved to his son's home in Vaterstetten, near Munich, where he continued writing and corresponding until his death in 1916, only one day after his 78th birthday.

## Physics

Most of Mach's initial studies in the field of experimental physics concentrated on the interference, diffraction, polarization and refraction of light in different media under external influences. From there followed important explorations in the field of supersonic fluid mechanics. Mach and physicist-photographer Peter Salcher presented their paper on this subject[15] in 1887; it correctly describes the sound effects observed during the supersonic motion of a projectile. They deduced and experimentally confirmed the existence of a shock wave of conical shape, with the projectile at the apex.[16] The ratio of the speed of a fluid to the local speed of sound vp/vs is now called the Mach number. It is a critical parameter in the description of high-speed fluid movement in aerodynamics and hydrodynamics. Mach also contributed to cosmology the hypothesis known as Mach's principle.

## Philosophy of science

Bust of Mach in the Rathauspark (City Hall Park) in Vienna, Austria

### Empirio-criticism

From 1895 to 1901, Mach held a newly created chair for "the history and philosophy of the inductive sciences" at the University of Vienna.[17] In his historico-philosophical studies, Mach developed a phenomenalistic philosophy of science which became influential in the 19th and 20th centuries. He originally saw scientific laws as summaries of experimental events, constructed for the purpose of making complex data comprehensible, but later emphasized mathematical functions as a more useful way to describe sensory appearances. Thus scientific laws while somewhat idealized have more to do with describing sensations than with reality as it exists beyond sensations.[18]

The goal which it (physical science) has set itself is the simplest and most economical abstract expression of facts.

When the human mind, with its limited powers, attempts to mirror in itself the rich life of the world, of which it itself is only a small part, and which it can never hope to exhaust, it has every reason for proceeding economically.

In reality, the law always contains less than the fact itself, because it does not reproduce the fact as a whole but only in that aspect of it which is important for us, the rest being intentionally or from necessity omitted.

In mentally separating a body from the changeable environment in which it moves, what we really do is to extricate a group of sensations on which our thoughts are fastened and which is of relatively greater stability than the others, from the stream of all our sensations.

Suppose we were to attribute to nature the property of producing like effects in like circumstances; just these like circumstances we should not know how to find. Nature exists once only. Our schematic mental imitation alone produces like events.

Mach's positivism also influenced many Russian Marxists, such as Alexander Bogdanov (1873–1928). In 1908, Lenin wrote a philosophical work, Materialism and Empirio-criticism (published 1909), in which he criticized Machism and the views of "Russian Machists" (Lenin also cited in this work the concept of the 'ether', as the medium through which light waves propagated, and the concept of time as an absolute). Empirio-criticism is the term for the rigorously positivist and radically empirical philosophy established by the German philosopher Richard Avenarius and further developed by Mach, which claims that all we can know is our sensations and that knowledge should be confined to pure experience.[19]

In accordance with empirio-critical philosophy, Mach opposed Ludwig Boltzmann and others who proposed an atomic theory of physics. Since one cannot observe things as small as atoms directly, and since no atomic model at the time was consistent, the atomic hypothesis seemed to Mach to be unwarranted, and perhaps not sufficiently "economical". Mach had a direct influence on the Vienna Circle philosophers and the school of logical positivism in general.

To Mach are attributed a number of principles that distill his ideal of physical theorisation—what is now called "Machian physics":

1. It should be based entirely on directly observable phenomena (in line with his positivistic leanings)[20]
2. It should completely eschew absolute space and time in favor of relative motion[21]
3. Any phenomena that would seem attributable to absolute space and time (e.g., inertia and centrifugal force) should instead be seen as emerging from the large scale distribution of matter in the universe.[22]

The last is singled out, particularly by Albert Einstein, as "the" Mach's principle. Einstein cited it as one of the three principles underlying general relativity. In 1930, he stated that "it is justified to consider Mach as the precursor of the general theory of relativity",[23] though Mach, before his death, would apparently reject Einstein's theory.[24] Einstein was aware that his theories did not fulfill all Mach's principles, and no subsequent theory has either, despite considerable effort.

### Phenomenological constructivism

According to Alexander Riegler, Ernst Mach's work was a precursor to the influential perspective known as constructivism.[25] Constructivism holds that all knowledge is constructed rather than received by the learner. He took an exceptionally non-dualist, phenomenological position. The founder of radical constructivism, von Glasersfeld, gave a nod to Mach as an ally.

Spinning chair devised by Mach to investigate the experience of motion

## Physiology

In 1873, independently of each other[26] Mach and the physiologist and physician Josef Breuer discovered how the sense of balance (i.e., the perception of the head's imbalance) functions, tracing its management by information which the brain receives from the movement of a fluid in the semicircular canals of the inner ear. That the sense of balance depended on the three semicircular canals was discovered in 1870 by the physiologist Friedrich Goltz, but Goltz did not discover how the balance-sensing apparatus functioned. Mach devised a swivel chair to enable him to test his theories, and Floyd Ratliff has suggested that this experiment may have paved the way to Mach's critique of a physical conception of absolute space and motion.[27]

## Psychology

Exaggerated contrast between edges of the slightly differing shades of gray, appears as soon as they touch

In the area of sensory perception, psychologists remember Mach for the optical illusion called Mach bands. The effect exaggerates the contrast between edges of the slightly differing shades of gray, as soon as they contact one another, by triggering edge-detection in the human visual system.[28]

More clearly than anyone before or since Mach made the distinction between what he called physiological (specifically visual) and geometrical spaces.[29]

Mach's views on mediating structures inspired B. F. Skinner's strongly inductive position, which paralleled Mach's in the field of psychology.[30]

## Eponyms

In homage his name was given to:

## Mach's principal works in English

• The Science of Mechanics (1883)
• The Analysis of Sensations (1897)[31]
• Popular Scientific Lectures (1895)
• Space and Geometry from the Point of View of Physical Inquiry (October 1903) In The Monist, Vol. XIV, No. I
• History and Root of the Principle of the Conservation of Energy (1911)
• The Principles of Physical Optics (1926)
• Knowledge and Error (1976)
• Principles of the Theory of Heat (1986)
• Fundamentals of the Theory of Movement Perception (2001)

## References

1. ^ Mach, E. (1960 [1883]), The Science of Mechanics, LaSalle, IL: Open Court Publishing, p. 284.
2. ^ whonamedit.com, Ernst Waldfried Josef Wenzel Mach
3. ^ Jagdish Mehra, Helmut Rechenberg, The Historical Development of Quantum Theory, page 47
4. ^ stanford.edu, Ernst Mach First published Wed May 21, 2008; substantive revision Tue Apr 28, 2009, Mach interest in physiology, Johannes Peter Müller and his students, Ernst Brüke and Carl Ludwig, started a new school of physiology in 1840s.
5. ^ John T. Blackmore, Ernst Mach: His Work, Life, and Influence, 1972, p. 44.
6. ^ John T. Blackmore, Ernst Mach: His Work, Life, and Influence, 1972, p. 196.
7. ^ "Ernst Mach". Encyclopædia Britannica. 2016. Retrieved January 6, 2016.
8. ^ John T. Blackmore (1972), Ernst Mach; his work, life, and influence, Berkeley: University of California Press, ISBN 978-0520018495, OCLC 534406, 0520018494
9. ^ R. S. Cohen; Raymond J. Seeger (1975). Ernst Mach, Physicist and Philosopher. Springer. p. 158. ISBN 978-90-277-0016-2. And Mach, in personal conviction, was a socialist and an atheist.
10. ^ Cf. Ursula Baatz: "Ernst Mach – The Scientist as a Buddhist?" In: John Blackmore (ed.): Ernst Mach — A Deeper Look. Documents and New Perspectives (Boston Studies in the Philosophy of Science, vol. 143). Springer, Dordrecht 1992, pp. 183–199.
11. ^ John T. Blackmore (1972). "Chapter 18 - Mach and Buddhism". Ernst Mach, His Work, Life, and Influence]. University of California Press. p. 293. ISBN 978-0520018495. Mach was logically a Buddhist and illogically a believer in science.
12. ^ John D. Anderson, Jr. "Research in Supersonic Flight and the Breaking of the Sound Barrier -- Chapter 3". history.nasa.gov. p. 65. Retrieved 5 September 2016.
13. ^ On this interdependency of Mach's physics, physiology, history and philosophy of science see Blackmore (1972), Blackmore (ed.) 1992 and Hentschel 1985 against Paul Feyerabend's efforts to decouple these three strands.
14. ^ Yourgrau, P. (2005). A World Without Time: The Forgotten Legacy of Gödel and Einstein. Allen Lane
15. ^ Mach, Ernst; Salcher, Peter (1887). "Photographische Fixirung der durch Projectile in der Luft eingeleiteten Vorgänge". Sitzungsber. Kaiserl. Akad. Wiss., Wien, Math.-Naturwiss. Cl. (in German). 95 (Abt. II): 764–780. Retrieved 24 October 2015.
16. ^ Scott, Jeff (9 November 2003). "Ernst Mach and Mach Number". Aerospaceweb.org. Retrieved 24 October 2015.
17. ^ On Mach's historiography, cf., e.g., Hentschel (1988); on his impact in Vienna, see Stadler et al. (1988), and Blackmore et al. (2001).
18. ^ Selections are taken from his essay The Economical Nature of Physical Inquiry, excerpted by Kockelmans and slightly corrected by Blackmore. (citation below).
19. ^ "empirio-criticism": entry in The Blackwell Dictionary of Western Philosophy.).
20. ^ Barbour, J. The End of Time, p. 220: "In the Machian view, the properties of the system are exhausted by the masses of the particles and their separations, but the separations are mutual properties. Apart from the masses, the particles have no attributes that are exclusively their own. They — in the form of a triangle — are a single thing. In the Newtonian view, the particles exist in absolute space and time. These external elements lend the particles attributes — position, momentum, angular momentum — denied in the Machian view. The particles become three things. Absolute space and time are an essential part of atomism."
21. ^ Penrose, R., The Road to Reality, p. 753: "Mach’s principle asserts that physics should be defined entirely in terms of the relation of one body to another, and that the very notion of a background space should be abandoned"
22. ^ Mach, E. The Science of Mechanics. "> [The] investigator must feel the need of ... knowledge of the immediate connections, say, of the masses of the universe. There will hover before him as an ideal insight into the principles of the whole matter, from which accelerated and inertial motions will result in the same way.
23. ^ Quoted in Pais, Subtle is the Lord, 2005, OUP
24. ^ The preface of the posthumously published Principles of Physical Optics explicitly rejects Einstein's relativistic views but it has been argued that the text is inauthentic; see Gereon Wolters, Mach and Einstein, or Clearing Troubled Waters in the History of Science. "Einstein and the Changing Worldviews of Physics". Birkhäuser, Boston, 2012. 39-57.
25. ^ Riegler, A. (2011) "Constructivism". In: L'Abete, L. (Ed.) Paradigms in Theory Construction, pp. 235–255 (doi:10.1007/978-1-4614-0914-4_13).
26. ^ Hawkins, J.E. and Schacht, J. "The Emergence of Vestibular Science" (Part 8 of "Sketches of Otohistory") in Audiology and Neurotology, April 2005.
27. ^ Ratliff, Floyd (1975). "On Mach's Contributions to the Analysis of Sensations". In Seeger, Raymond J.; Cohen, Robert S. (eds.). Ernst Mach, Physicist and Philosopher.
28. ^ Ratliff, Floyd (1965). Mach bands: quantitative studies on neural networks in the retina. Holden-Day.
29. ^ Mach, E. (1906) Space and Geometry. Chicago: Open Court Publishing.
30. ^ Mecca Chiesa (1994). Radical Behaviorism: The Philosophy and the Science. Authors Cooperative. ISBN 978-0-9623311-4-5.
31. ^ See Mach, Ernst (1897). Williams, C.W. (ed.). Contributions to the Analysis of Sensation (1 ed.). Chicago: Open Court Publishing Company. Retrieved 13 July 2014. via Archive.org

• Erik C. Banks: Ernst Mach's World Elements. A Study in Natural Philosophy. Dordrecht: Kluwer (now Springer), 2013.
• John T. Blackmore: Ernst Mach. His Life, Work, and Influence. Berkeley and Los Angeles: University of California Press, 1972.
• John Blackmore and Klaus Hentschel (eds.): Ernst Mach als Außenseiter. Vienna: Braumüller, 1985 (with select correspondence).
• John T. Blackmore (ed.): Ernst Mach – A Deeper Look. Documents and New Perspectives. Dordrecht: Springer, 1992.
• John T. Blackmore, Ryoichi Itagaki and Setsuko Tanaka (eds.): Ernst Mach's Vienna 1895–1930. Or Phenomenalism as Philosophy of Science. Dordrecht: Springer, 2001.
• John T. Blackmore, Ryoichi Itagaki and Setsuko Tanaka (eds.): Ernst Mach's Science. Kanagawa: Tokai University Press, 2006.
• John T. Blackmore, Ryoichi Itagaki and Setsuko Tanaka: Ernst Mach's Influence Spreads. Bethesda: Sentinel Open Press, 2009.
• John T. Blackmore, Ryoichi Itagaki and Setsuko Tanaka: Ernst Mach's Graz (1864–1867), where much science and philosophy were developed. Bethesda: Sentinel Open Press, 2010.
• John T. Blackmore: Ernst Mach's Prague 1867–1895 as a human adventure, Bethesda: Sentinel Open Press, 2010.
• William Everdell: The First Moderns. Profiles in the Origins of Twentieth-Century Thought. Chicago: University of Chicago Press, 1997.
• Rudolf Haller and Friedrich Stadler (eds.): Ernst Mach – Werk und Wirkung. Vienna: Hoelder-Pichler-Tempsky, 1988.
• Klaus Hentschel: "On Paul Feyerabend's version of 'Mach's theory of research and its relation to Albert Einstein'", Studies in History and Philosophy of Science 16 (1985): 387-394.
• Klaus Hentschel: "Die Korrespondenz Duhem-Mach: Zur 'Modellbeladenheit' von Wissenschaftsgeschichte'", Annals of Science 45 (1988): 73-91 (with their complete correspondence).
• Klaus Hentschel: "Ernst Mach", in Arne Hessenbruch (ed.): Reader's Guide to the History of Science. London: Routledge, 2013, p. 427f.
• D. Hoffmann and H. Laitko (eds.): Ernst Mach – Studien und Dokumente. Berlin, 1991.
• Joseph J. Kockelmans: Philosophy of science. The historical background. New York: The Free Press, 1968.
• Jiří Procházka: Ernst Mach /1838–1916/ Genealogie, 3 vols. Brno, 2007–2010. ISBN 80-903476-3-0, 80-903476-7-3, 978-80-903476-0-1.
• V. Prosser and J. Folta (eds.): Ernst Mach and the development of Physics – Conference Papers, Prague: Universitas Carolina Pragensis, 1991.
• Joachim Thiele: Wissenschaftliche Kommunikation – Die Korrespondenz Ernst Machs", Kastellaun: Hain, 1978 (with select correspondence).