dr_raha_spc ( at work )
.. "Sign of the Cross" ..
.. as an example for application of "ART".. as "forecasted" for JPa/QzC in context of "Wittgenstein stuff"
from Wikipedia (shortened):
The Einstein Cross QSO 2237+0305 is a gravitationally lensed quasar found in Pegasus, positioned directly behind Huchra's Lens ZW 2237+030. It is quadruply imaged, forming a nearly perfect cross, with the lensing galaxy at its center.
The quasar is located about 8*10**9 light years from Earth, while the lensing galaxy is located at a distance of 0,4*10**9 light years.
A gravitational lens is formed when the light from a distant, bright source (such as a quasar) is "bent" around a massive object (such as a cluster of galaxies) between the source object and the observer. The gravitational lensing effect is one of the predictions of Albert Einstein's general theory of relativity (GRT/ART).
The Einstein field equations (EFE) are the core of general relativity theory. The EFE describe how mass and energy (represented in the stress-energy tensor T) are related to the curvature of space-time (represented in the Einstein tensor G). In index notation, the EFE reads as follows:
G(a,b) + L*g(a,b) = (d/c**4) * T(a,b)
where g(a,b) is the metric tensor, L the cosmological constant, c the speed of light in vacuum and d is 8*pi*(gravitational constant)
The EFE, being non-linear differential equations for the metric, are often difficult to solve. There are a number of strategies used to solve them. For example, one strategy is to start with an "Ansatz" (educated guess) of the final metric, and refine it until it is specific enough to support a coordinate system, but still general enough to yield a set of simultaneous differential equations with unknowns that can be solved for. Metric tensors resulting from cases where the resultant differential equations can be solved exactly for a physically reasonable distribution of energy-momentum are called exact solutions. Examples of important exact solutions include the "Schwarzschild solution" (BHS) and the "Friedman-Lemaître-Robertson-Walker solution" (BBS)
The cosmological constant L (i.g. Lambda) was re-established (after eliminated by Einstein in knowledge of Friedmanns solution) for the explanation of the "accelerated expansion of the universe" in the "Lambda-ColdDarkMatter" (LCDM) concordance model ..
.. "Sign of the Cross" ..
.. as an example for application of "ART".. as "forecasted" for JPa/QzC in context of "Wittgenstein stuff"
from Wikipedia (shortened):
The Einstein Cross QSO 2237+0305 is a gravitationally lensed quasar found in Pegasus, positioned directly behind Huchra's Lens ZW 2237+030. It is quadruply imaged, forming a nearly perfect cross, with the lensing galaxy at its center.
The quasar is located about 8*10**9 light years from Earth, while the lensing galaxy is located at a distance of 0,4*10**9 light years.
A gravitational lens is formed when the light from a distant, bright source (such as a quasar) is "bent" around a massive object (such as a cluster of galaxies) between the source object and the observer. The gravitational lensing effect is one of the predictions of Albert Einstein's general theory of relativity (GRT/ART).
The Einstein field equations (EFE) are the core of general relativity theory. The EFE describe how mass and energy (represented in the stress-energy tensor T) are related to the curvature of space-time (represented in the Einstein tensor G). In index notation, the EFE reads as follows:
G(a,b) + L*g(a,b) = (d/c**4) * T(a,b)
where g(a,b) is the metric tensor, L the cosmological constant, c the speed of light in vacuum and d is 8*pi*(gravitational constant)
The EFE, being non-linear differential equations for the metric, are often difficult to solve. There are a number of strategies used to solve them. For example, one strategy is to start with an "Ansatz" (educated guess) of the final metric, and refine it until it is specific enough to support a coordinate system, but still general enough to yield a set of simultaneous differential equations with unknowns that can be solved for. Metric tensors resulting from cases where the resultant differential equations can be solved exactly for a physically reasonable distribution of energy-momentum are called exact solutions. Examples of important exact solutions include the "Schwarzschild solution" (BHS) and the "Friedman-Lemaître-Robertson-Walker solution" (BBS)
The cosmological constant L (i.g. Lambda) was re-established (after eliminated by Einstein in knowledge of Friedmanns solution) for the explanation of the "accelerated expansion of the universe" in the "Lambda-ColdDarkMatter" (LCDM) concordance model ..