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An Einstein Ring is a special case of gravitational lensing, caused by the exact alignment of the source, lens, and observer. This results in symmetry around the lens, causing a ring-like structure. [2] The geometry of a complete Einstein ring, as caused by a gravitational lens. The size of an Einstein ring is given by the Einstein radius.
A(u) always decreases as u increases, so the closer the alignment, the brighter the source becomes. As u approaches infinity, A(u) approaches 1, so that at wide separations, microlensing has no effect. Finally, as u approaches 0, for a point source A(u) approaches infinity as the images approach an Einstein ring.
For a dense cluster with mass M c ≈ 10 × 10 15 M ☉ at a distance of 1 Gigaparsec (1 Gpc) this radius could be as large as 100 arcsec (called macrolensing). For a Gravitational microlensing event (with masses of order 1 M ☉) search for at galactic distances (say D ~ 3 kpc), the typical Einstein radius would be of order milli-arcseconds ...
The same value as Soldner's was calculated by Einstein in 1911 based on the equivalence principle alone. [13]: 3 However, Einstein noted in 1915, in the process of completing general relativity, that his (and thus Soldner's) 1911-result is only half of the correct value. Einstein became the first to calculate the correct value for light bending.
Strong gravitational lensing is a gravitational lensing effect that is strong enough to produce multiple images, arcs, or Einstein rings. Generally, for strong lensing to occur, the projected lens mass density must be greater than the critical density , that is Σ c r {\displaystyle \Sigma _{cr}} .
Like the traditional ellipticity, the magnitudes of both of these quantities range from 0 (circular) to 1 (a line segment). The position angle is encoded in the complex phase, but because of the factor of 2 in the trigonometric arguments, ellipticity is invariant under a rotation of 180 degrees.
Einstein's paper includes a fundamental description of the kinematics of the rigid body, and it did not require an absolutely stationary space, such as the aether. Einstein identified two fundamental principles, the principle of relativity and the principle of the constancy of light (light principle), which served as the axiomatic basis of his ...
Albert Einstein. Relativity: the Special and the General Theory, 10th edition (there are a total of 17 editions). ISBN 0-517-029618 at Project Gutenberg; Relativity: The Special and General Theory public domain audiobook at LibriVox; Albert Einstein, Relativity: The Special and General Theory (1920/2000) ISBN 1-58734-092-5 at Bartleby.com