# Visual simulation of gravitational lensing

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## Main Question or Discussion Point

Is there a way to generate an accurate visual computer simulation of gravitational lensing?

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Thanks OmCheeto,
But this link seems to relate to a physical simulation of gravitational lensing and not a computerized one.
I am looking for a computerized one, which enables to play with the properties of the astronomical objects and equipment, hence to be able to visually observe the change in the lensing output, as these properties are changed.

OmCheeto
Gold Member
Thanks OmCheeto,
But this link seems to relate to a physical simulation of gravitational lensing and not a computerized one.
I am looking for a computerized one, which enables to play with the properties of the astronomical objects and equipment, hence to be able to visually observe the change in the lensing output, as these properties are changed.
The second link I posted appears to be a computerized one.
From wiki's entry on gravitational lensing, the maths doesn't look too difficult.

Θ = 4GM / rc2

roineust

Photo: Lensshoe_hubble.jpg: ESA/Hubble & NASA derivative work: Bulwersator (talk) - Lensshoe_hubble.jpg

What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured above, the gravity of a luminous red galaxy (LRG) has gravitationally distorted the light from a much more distant blue galaxy. More typically, such light bending results in two discernible images of the distant galaxy, but here the lens alignment is so precise that the background galaxy is distorted into a horseshoe -- a nearly complete ring. Since such a lensing effect was generally predicted in some detail by Albert Einstein over 70 years ago, rings like this are now known as Einstein Rings. Although LRG 3-757 was discovered in 2007 in data from the Sloan Digital Sky Survey (SDSS), the image shown above is a follow-up observation taken with the Hubble Space Telescope's Wide Field Camera 3. Strong gravitational lenses like LRG 3-757 are more than oddities -- their multiple properties allow astronomers to determine the mass and dark matter content of the foreground galaxy lenses.

A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's general theory of relativity. (Classical physics also predicts the bending of light, but only half that predicted by general relativity.) Although Einstein made unpublished calculations on the subject in 1912, Orest Khvolson (1924) and Frantisek Link (1936) are generally credited with being the first to discuss the effect in print. However, this effect is more commonly associated with Einstein, who published an article on the subject in 1936. Fritz Zwicky posited in 1937 that the effect could allow galaxy clusters to act as gravitational lenses. It was not until 1979 that this effect was confirmed by observation of the so-called "Twin QSO" SBS 0957+561.

A visual simulation of GL below ( attached as a GIF):

A remote light source passing behind a gravitational lens. There is a large point mass in the center acting as a lens. The aqua circle is how we would see the light source if there was no lens, while the white spots/circle is the light source as seen through the lens. If the light source is collinear with the earth and lens, the image is an "Einstein ring". When the source is off this line we see a double image. As it moves far away, one of the images gets fainter while the other one is almost not affected by the lens any more (thus coinciding with cyan circle).

roineust