- A dictionary of medical eponyms

Mach's principle

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In cosmology, hypothesis that the inertial effects of mass are not innate in a body, but is determined by the quantity and distribution of matter in the universe. According to Mach, inertia applies only as a function of the interaction between one body and other bodies in the universe, even at enormous distances ("matter there governs inertia here"). This principle influenced Albert Einstein in his work on the general theory of relativity, and Einstein coined the term Mach’s principle, in 1918.

Inertia is the tendency of a body at rest to remain at rest and of a body in motion to continue in motion in the same direction.


  • E. Mach:
    Die Mechanik in ihrer Entwicklung historisch-kritisch dargestellt.
    Leipzig: Brockhaus, 1883. 7th edition, 1912. 8th edition, 1921.
    English translation by Thomas J. McCormick:
    The Science of Mechanics. A critical and historical exposition of its principals.
    The Open Court Publishing Co. 1893.
  • Julian B. Barbour and Herbert Pfister, editors:
    Mach's Principle: From Newton's Bucket to Quantum Gravity. Boston, MA: Birkhäuser, 1995.
  • C. W. Misner, K. S. Thorne, and J. A. Wheeler:
    Gravitation. San Francisco, CA: W. H. Freeman, 1973.

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