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:
“Nature predominates over the human will in all works of even the fine arts, in all that respects their material and external circumstances. Nature paints the best part of the picture, carves the best of the statue, builds the best part of the house, and speaks the best part of the oration.”
—Ralph Waldo Emerson (1803–1882)
“The poet will write for his peers alone. He will remember only that he saw truth and beauty from his position, and expect the time when a vision as broad shall overlook the same field as freely.”
—Henry David Thoreau (1817–1862)
“We all have—to put it as nicely as I can—our lower centres and our higher centres. Our lower centres act: they act with terrible power that sometimes destroys us; but they don’t talk.... Since the war the lower centres have become vocal. And the effect is that of an earthquake. For they speak truths that have never been spoken before—truths that the makers of our domestic institutions have tried to ignore.”
—George Bernard Shaw (1856–1950)