Gravitational lensing occurs when light from a distant object is bent as it travels to an observer, due to passing through the gravitational field of a massive object (such as a galaxy, or black hole).

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The equation of the deflection angle

I am reading this book about Introduction to Gravitational lensing. $\alpha$ is defined here as the deflection angle. I am struggling to understand Equations 3.24, 3.25, 3.26. What does ...
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Are there any experimental data for light bending angle? [duplicate]

The gravitational lensing formula is given by equation $a=4M/r$. Is there any experimental data for this equation. I am trying to plot a curve for this equation and the real experimental data and ...
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Gravitational lensing experimental data [duplicate]

Is there any experimental data for the gravitational lensing equation $$ \alpha=\frac{4M}{b} $$ where $b$ is the distance of closest approach, $M$ is the mass of the object. I tried Google but ...
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What is the future of gravitional lensing? [closed]

What do physicists expect to find or accomplish with gravitational lensing in the next 15 years? Is there a specific type of object, or a concept that they are looking for?
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How does an object such as a galaxy split the image from a more distant galaxy into two images?

I was reading a recent discussion on gravitational lensing, in which it described the bending of light from a distant galaxy as it passed a nearer galaxy to produce two images of the same distant ...
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Is Gravitational Lensing Wrong?

Could gravitational lensing be the refraction of hydrogen, helium, gases and cosmic dust? Refraction is the change in direction of propagation of a wave due to a change in its transmission medium. ...
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Is “gravitational lensing” due to momentum or curvature of space?

I'm confused about how massless particle is influenced by gravitational force. Some source point to the energy conversion to mass and vice versa so light is treated similarly, other source mentioned ...
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Can objects orbit around gravitational lensing of a black hole's gravity waves?

In a previous post I was told that gravitational lenses focus gravitational waves. Can objects orbit around gravitational lensing of a black hole's gravity waves?
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Do gravitational lenses work on gravitational waves?

Do gravitational lenses work on gravitational waves? Could we get an Einstein cross of gravity?
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At what rate does light 'bend' around the surface of the earth?

Since the g force of earth is 9.8 m/s*2 does that mean light 'drops' at that rate as it travels past earth? Or is general relativity a lot more complex than that?
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How much $G$ is required to bend light? [duplicate]

How much $G$ is required to bend light?. Also, please explain what happens if a powerful light beam in a vacuum is intercepted by electromagnetic fields on either sides.
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Can curvature waves in f(R) theories explain gravitational lensing in cluster collisions?

The Einstein-Hilbert action leading to Einstein's equations is $$S\sim\int R \sqrt{-g}\, {\rm d}^4 x$$ There is a class of modifications of Einstein's relativity called $f(R)$ theories of gravity ...
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Can diffraction be used like gravitational lensing [closed]

I was thinking that in both the cases of diffraction and gravitational lensing, light is bend to some extent mimicking the lens effect. My Question is, Can diffraction be used like gravitational ...
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Coulomb's Law in the presence of a strong gravitational field

I was under the impression that the $1/r^2$ falloff of various forces were because of the way the area of a expanding sphere scales. But that strict $1/r^2$ falloff would only be globally true in a ...
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Viewing a Time-Dilated Space

I'm fascinated by space and physics but not exactly well-versed in them, so I'll try to keep this question as simple as possible. Imagine a person acting as an observer in a room with two large ...
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Graviational Lensing Data

Can anyone provide me with (or point me to) real life gravitational lensing data that I can plug in to the first equation on this page (the standard lensing equation): ...
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Spiral galaxies and gravity lenses

Spiral Galaxies must have a great deal more mass than elliptical galaxies of the same size in order to account for the flat velocity curve. I've seen references of eight to ten times the visible ...
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Best Research Documentation Habit for Computational Physics Research [closed]

I am currently doing research in a subset of the field of gravitational lensing called weak lensing. I am simulating blended galaxy profiles and creating an algorithm to extract the true parameters I ...
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If MOND theory doesn't explain gravitational lensing, couldn't well placed black holes explain it?

When I first heard about star velocity as a function of its distance from the center of the galaxy and the difference between prediction and observation I immediately thought "there must be a ...
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Gravitational lens to illuminate a planet?

I've been involved in a Internet debate: Is it possible to have a special cosmic configuration consisted of multiple bodies such that a planet's surface can be lit up by light focused by ...
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Do alternate theories for Dark Matter (like MOND) explain it's effect on gravitational lensing?

For a long time, I was sceptical about the evidence for dark matter. To me, it seemed like a pretty big leap to make when we have no idea whether or not our current models of gravity should apply ...
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Bending of light - photon's inertia instead of mass

Using classical mechanics, the formula for gravitational attraction is $$F = G\frac{m_1m_2}{r^2}.$$ This formula does not work for photons, and we need to use Einstein's theory of gravity to ...
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Does light bend in a vacuum?

I'm familiar with gravitational lensing but still I'm wondering if there is experiments (conducted here on Earth) which show that light bends due to gravity. For example mirrors setup to hold the ...
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Is it true that gravitational lensing only occurs for objects made of plasma?

The question concerns this video: It says that the Gravitational Lens effect is an illusion, meaning it's not caused by gravity but by change in density of a plasma atmosphere. It claims further ...
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How is gravitational lensing possible? [duplicate]

How is it possible that a force that affects mass (gravity) can affect massless particles like photons?
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Luminosity distance from angular diameter distance

Consider that I know the cosmological angular diameter distance at a given redshift : $$D_{A}\left(z\right)=\frac{x_{object}}{\theta_{observer}}$$ Is there a general formula to compute the ...
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Differences between strong, weak, and micro lensing distinct or subtle?

In gravitational lensing, there are three categories of lensing: strong, weak, and micro. As I understand it, strong lensing (just as the name implies) occurs when a source and a gravitational lens ...
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Trajectory of a photon around a Schwarzschild black hole?

Consider a photon coming from the infinity in a unbounded orbit to a Schwarzschild black hole (Schwarzschild radius $r_{s}$) (see this for illustration). Its impact parameter is $b$ and its distance ...
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Relation between impact parameter and distance of closest approach of a light ray in Schwarzschild Geodesics

The following wikipedia articles are incompatible : Two body problem / bending of light by gravity Schwarzschild geodesics / bending of light by gravity According to both articles, the equation ...
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Why does gravitational lensing bend light rather than absorbing it?

I've read that gravitational lensing bends the light; I am a little confused about black holes and why lensing produces different results. Black holes absorb light whereas lensing should have also ...
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Merger happening tangentially, but dark matter at both sides?

According to this news, The expectation of "unaccounted energy" comes from the fact the merger of galaxy clusters is occurring tangentially to the observers' line-of-sight. This means they are ...
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CMB curly B-modes and dark matter

I raised a question a while ago regarding weak gravitational lensing of galaxies and the CMB. With all the fuzz with the BICEP2 data, I think it is time to raise even more questions about this amazing ...
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concept of density in gravitational lensing

I may just be being very dense (no pun intended) but i'm reading up on gravitational lensing and it seems to require a notion of density (e.g. see here) I'm working on a question involving light ...
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Gravitational lensing image from merging black holes

What kind of image would a transcient toroidial black hole merger produce from it's gravitalional lensing effect? http://arxiv.org/abs/gr-qc/9905039 What does a torus shaped lens actually look like? ...
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Is it possible to make an optical lense that is an analog to a gravitational lense?

There are many lenses that do all sorts of things. eg. horshoe lenses twist light, meta material lenses can boggle the mind. Is it possible to make an optical lense that is an analog to a ...
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Would gravitons follow the same trajectory as photons through a gravitational lense?

Would gravitons follow the same trajectory as photons through a gravitational lense? would all other particles follow the same trajectory?
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Do gravitational lenses have a focus point?

Do gravitational lenses have a focus point? Could I burn space ants?
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Calculating the size of the “lensing sphere” of a black hole

Given a black hole of some size, say $10^8$ solar masses, how can the size of its sphere of influence of light be calculated? To clarify, ultimately I'd like to be able to calculate the apparent ...
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Is there a minimum mass is required for light to be noticeably bent?

The sun bends the trajectory of light slightly. And a black hole will bend the trajectory entirely. This is all dependent on the proximity to the source of gravity. For a given angle, is there some ...
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What causes there to be an offset between the light lensing through the space neighboring galaxy clusters and the galaxy clusters themselves?

http://www.wired.com/wiredscience/2013/01/musket-ball-dark-force/ The reason this is strange is that dark matter is thought to barely interact with itself. The dark matter should just coast ...
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Weak gravitational lensing multispectral, multibackground correlations

My understanding of weak gravitational lensing is that it assumes random alignment distribution of galaxies in order to estimate statistical shear and convergences, which are used to estimate matter ...
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Slow light and gravitational lensing

It has been proposed that the Sun's gravitational lens be used to observe distant objects, but according to relativity a spacecraft would need to be 550 AU away in order to take advantage of the ...
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Is weak lensing the statistical effect of microlensing?

I am looking into the effects of gravitational lensing of gravitational waves. I know that gravitons travel along null geodesics, just as photons, and so they will suffer the same deflection angle by ...
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Liouville's theorem and gravitationally deflected lightpaths

It is customary in gravitational lensing problems, to project both the background source and the deflecting mass (e.g. a background quasar, and a foreground galaxy acting as a lens) in a plane. Then, ...
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Are different frequencies of light lensed differently during gravitational lensing a bit like refraction?

So I was wondering about the event horizon on a black hole. And wondering if the point of no return for radio waves vs gamma rays would be different. I guess the logic being, since gamma rays have ...
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The transit of Venus and solar neutrino rates

The following question was posed at the end of Maury Goodman's June 2012 long-baseline neutrino newsletter. During the Venus transit of the sun, were more solar neutrinos absorbed in Venus, or ...
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How does gravitational lensing account for Einstein's Cross?

Einstein's Cross has been attributed to gravitational lensing. However, most examples of gravitational lensing are crescents known as Einstein's rings. I can easily understand the rings and crescents, ...
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Gravitational lensing or cloud refraction?

My current understanding of gravitational lensing follows When a star or other massive body passes between us and another star, the phenomenon generally labeled 'gravitational lensing' occurs. The ...