Modified Newtonian dynamics

In astrophysics, the modified Newtonian dynamics (MOND) is a burgeoning theory that attempts to explain the galaxy rotation problem by modifying Newton's second law of motion. (The most widely accepted approach to explaining this problem postulates the existence of dark matter.) MOND was proposed in 1983 by Mordehai Milgrom. The central pillar of MOND is the assumption that (F = ma) is a high-acceleration approximation of a more accurate law that describes all accelerations. The proposed modification would only become relevant when the total acceleration of a body falls significantly below the constant a_0. Consequently, observations of this behavior could never be made on Earth.

Related Topics:
Astrophysics - Galaxy rotation problem - Dark matter - Mordehai Milgrom - Earth

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Although Milgrom and others have catalogued a respectable sum of persuasive evidence in favor of MOND, there has not been enough compelling research to conclusively substantiate or disprove the theory. Calculations suggest that the parameters required to gather direct experimental evidence can be found only far outside our solar system (beyond the overwhelming influence of the Sun's gravitational field). Therefore, it will be some time before the validity of MOND can be directly tested. Phenomena such as low surface brightness galaxies have yielded an abundance of indirect evidence on the matter, but in the absence of more varied data, such successes have been viewed as isolated. Many researchers have criticized MOND for 'adapting' its mathematics to the observed mass discrepancy instead of hypothesizing a true physical explanation. The theory is the minority view in the astrophysicist community.

Related Topics:
Sun - Low surface brightness galaxies - Mass discrepancy

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