The External Field Effect (EFE)
In MOND it turns out that if a weakly gravitationally bound system s, whose inner accelerations are expected to be of the order of 10−10 m s−2 from a Newtonian calculation, is embedded in an external gravitational field generated by a larger array of masses S, then, even if is uniform throughout the spatial extension of s, the internal dynamics of the latter is influenced by in such a way that the total acceleration within s is, actually, larger than 10−10 m s−2. In other words, the Strong Equivalence Principle is violated. Milgrom originally introduced such a concept to explain the fact that the expected phenomenology of dark matter—-to be explained in terms of MOND—-was absent just in some systems (open clusters) in which it should have, instead, been present. It was shown later by R. Scarpa and collaborators that also a number of globular clusters in the neighborhood of the Milky Way behave in the same way, that is MOND effects are seen even though the total (internal+external) field is above MOND acceleration limit.
Read more about this topic: Modified Newtonian Dynamics
Famous quotes containing the words external, field and/or effect:
“A tempest cracked on the theatre. Quickly,
The wind beat in the roof and half the walls.
The ruin stood still in an external world.
It had been real. It was something overseas
That I remembered, something that I remembered
Overseas, that stood in an external world.”
—Wallace Stevens (1879–1955)
“The frequent failure of men to cultivate their capacity for listening has a profound impact on their capacity for parenting, for it is mothers more than fathers who are most likely to still their own voices so they may hear and draw out the voices of their children.”
—Mary Field Belenky (20th century)
“The poem has a social effect of some kind whether or not the poet wills it to have. It has kinetic force, it sets in motion ... [ellipsis in source] elements in the reader that would otherwise be stagnant.”
—Denise Levertov (b. 1923)