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Consequently, a gravitational lens has no single focal point, but a focal line. The term "lens" in the context of gravitational light deflection was first used by O. J. Lodge, who remarked that it is "not permissible to say that the solar gravitational field acts like a lens, for it has no focal length". [11]
While gravitational lensing preserves surface brightness, as dictated by Liouville's theorem, lensing does change the apparent solid angle of a source. The amount of magnification is given by the ratio of the image area to the source area. For a circularly symmetric lens, the magnification factor μ is given by
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.
The geometry of gravitational lenses. In the following derivation of the Einstein radius, we will assume that all of mass M of the lensing galaxy L is concentrated in the center of the galaxy. For a point mass the deflection can be calculated and is one of the classical tests of general relativity.
J1000+0221 was the most distant gravitational lens galaxy known (up until the discovery of the IRC 0218 lens galaxy), and remains the most distant quad-image lens galaxy discovered so far. The measured distance the light has traveled, including the lensed deflection, is 9.4 billion light years. [ 4 ]
The foreground lens is a galaxy. When the background source is a quasar or unresolved jet, the strong lensed images are usually point-like multiple images; When the background source is a galaxy or extended jet emission, the strong lensed images can be arcs or rings. As of 2017, several hundred galaxy-galaxy (g-g) strong lenses have been ...
The iPhone 11 and 11 Pro series introduced an ultrawide lens; the latter two became the first triple-camera iPhones. The 11 has a dual-lens setup, lacking the telephoto lens of the 11 Pro and 11 Pro Max. The front camera is now capable of recording video at 4K as a result of a new 12 MP sensor, and can also capture slow-motion footage.
In spherical coordinates (,,,) , the Reissner–Nordström metric (i.e. the line element) is = = (+) (+) , where is the speed of light; is the proper time; is the time coordinate (measured by a stationary clock at infinity).