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Questions tagged [gravitational-lensing]

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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Galaxies rotations speeds questions

We accept epic gravitational lensing effects around invisible supermassive black holes, but do we consider possible gentle lensing effects in huge galactic structures observations ? Do we take time ...
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Factor for observed redshift - light dispersion (chromatic aberration) caused by a gravitational lensing

This thought tortured me for a while now, and I can't find if this has been hypothesized/discussed before, and if so, is there a consensus: Can redshift be to at least some degree a result of a ...
Andris's user avatar
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Numerical evaluation of gravitational light bending

I am looking into how light is being bent by objects of large masses with the intention of creating a numerical simulation of this (basically a ray tracer taking this phenomenon into account). I was ...
Pandicon's user avatar
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Given gravitational lensing, why would black holes visually appear black?

This image from Wikipedia, also referenced in this question, is an artist's vision of how a black hole should look like: However, given that a black hole is a gravitational lens strong enough to ...
Igor F.'s user avatar
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Are light rays always bent in any gravitational field, or just in a strong one like a black hole?

This is a follow-up question after this one: Yes, the curvature is enough to bend lasers. In fact, there is an interesting feature in Schwarzschild spacetime that might answer your question well. ...
Árpád Szendrei's user avatar
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Reaching a turning point in photon trajectory

Given the geodesic equations for a photon in a Schwarzchild or Kerr metric (provided by a near BH for example), the radial equation has usually two possible signs: \begin{equation} \dfrac{dr}{d\tau}= ...
gravitone123's user avatar
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Can stars bend light?

Is it possible for a star to be so big that its gravity can bend light like a black hole? If so, would the star appear dark or bright, or would it collapse on itself?
Kellan Heerdegen's user avatar
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Still having trouble understanding gravitational lensing [duplicate]

The normal diagram used to explain gravitational lensing shows a two-dimensional plane that is deflected by a heavy weight. This is a two dimensional description that requires an extra dimension to ...
Michael Mcgarry's user avatar
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Does gravitational lensing bend light of all wavelengths by the same amount?

Basically I am asking if gravitional lensing is bending or refracting light.
Michael Mcgarry's user avatar
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Gravitational field of the star changes the paths of light rays, how is this observed during eclipse?

The gravitational field of the star changes the paths of light rays in space-time from what they would have been had the star not been present. I understand that the light cones are bend slightly ...
Amit Naik's user avatar
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What effect causes stars to be optically enlarged at the Einstein ring of a black hole?

Sadly i do not know what this effect is called, but it can be seen in some simulations; Credit to Alessandro Roussel The same effect can be seen on the Wiki page for black holes. For a while now, me ...
ErikHall's user avatar
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What will happen to the light due to frame-dragging?

Imagine a rotating black hole is blocking a cluster of stars that I'm observing. Thanks to gravitational lensing I could still see the stars albeit shifted away from their original locations. So now ...
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Why isn't the "Dark Matter" in the Bullet Cluster supermassive black holes?

I've seen several videos that claim that the Bullet Cluster is evidence for Dark Matter. The general idea is that the gas is trapped on one side of the collision and the light-bending "Dark ...
The Shepard's user avatar
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How you would you detect weak negative spatial curvature that only existed in cosmic intergalactic voids?

If the large space voids between galaxies had uniformly-distributed "negative" gravitational lensing, would its presence be obvious from photos in the same way that the presence of Einstein ...
Kevin Marinas's user avatar
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Seeking Visualization Tools for Hypothetical Black Hole Concept

I have a idea I'd like to explore: If a black hole can bend light due to its immense gravitational attraction, could we imagine an 'inverted black hole'? In this hypothetical scenario, this object ...
Andr andrefff0 Faria Formagio 's user avatar
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How much gravitational lensing do we see from the Milky Way?

I assume that the Milky Way has a dark matter halo just like any other. If that is the case, if we look at a huge part of our own galaxy, do we actually see the gravitational lensing effect? How ...
Antoniou's user avatar
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Specifics of orbiting self-interaction in GR?

As the orbiting body emits its own gravitational field, its front would curve around the host. In doing so, if the lensing caused by the host is sufficient, it could hypothetically intersect with the ...
Logan J. Fisher's user avatar
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Could a person weigh so much as to cause gravitational lensing?

I'm a bit familiar with the concept of gravitational lensing. I also believe that all objects have some gravitational force, even if it's minuscule. Would an object as massive as a person cause any ...
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Derivation of Gravitational Lensing in Schutz's, "A First course in General Relativity" textbook

On page 310 of the third edition of the textbook, Schutz writes: Suppose now we assume $M u \ll 1$ but is not entirely negligible. Then if we define $$ y:=u(1-M u), \qquad u=y(1+M y)+\mathrm{O}\left(...
Virgo's user avatar
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Could we derive the mass of neutrinos using a supernova and gravitational lensing?

There are a lot of questions on this site about getting neutrino mass from timing the arrival of neutrinos vs light from a supernova, I believe this is different. If we see a galaxy that is ...
Joe's user avatar
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Polynomial regression with microlensing parameters

As a hobbyist I would like to learn more about microlensing by exploring some data and performing some simple regression analysis. Based on the exoplanet archive of microlensing planets https://...
shoggananna's user avatar
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Small Angle Approximation in Lensing Equation

In reading an article about gravitational lensing, I was pretty confused by the fact that the extra path travelled through the Lense compared with the direct path $OS$, in small angle approximation is ...
Sofvar's user avatar
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How do you intuitively understand of the Einsteinian portion of the gravitational lensing equation?

The total gravitational lensing equation is an addition of the Newtonian Solution $\left(\frac{2GM}{c^2r}\right)$ and the Einsteinian Solution $\left(\frac{2GM}{c^2r}\right)$ thus the combined ...
Python House's user avatar
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1 answer
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How do we know gravitational lensing is caused by gravity and not by a magnetic field [closed]

Is it possible that other factors could be contributing to the lensing effects we observe, particularly magnetic field disruptions? Light has a frequency, and my understanding is that a magnet can ...
Mike's user avatar
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Does gravitational lensing make objects that would be obscured behind other objects completely visible?

Reading a small amount about gravitational lensing and viewing many of the visualizations, it appeared that bodies directly behind other massive objects (from some point of view; namely galaxies ...
Thor Ether's user avatar
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Is a photon redshifted differently depending on whether it is passing inside a galaxy or in a cosmic void?

Consider two photons that are emitted in different directions from the same source in the Milky Way, a long time ago (redshift $z_i$.) One of the photons leaves the galaxy, travels for, say, 50 Mpc, ...
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Questions about first JWST image

Why do the circled galaxies seem to form long circular arcs that surround the white point at the center? And why do most of the galaxies in this image seem to be facing that same point? What is in ...
bloop's user avatar
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2 answers
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Mutual gravitational acceleration (or deflection) of light beams as a function of the angle between them

Given Einstein's famous equivalence between energy and mass, $E=mc^2$, a light beam with power, $P$, has an energy per unit length of $P/c$ and an equivalent mass per unit length of $P/c^3$. A short ...
Roger Wood's user avatar
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How to convert from polarization modes ($h_{+}$, $h_{×}$) to obtain spin-weighted spherical harmonic $h_{lm}$ as a function of $h_{+}$, $h_{×}$?

This question arises from a discussion in the thread How to convert from plus and cross polarization modes ($h_{+}$, $h_{×}$) to spin-weighted spherical harmonic $h_{lm}$? I was looking for a ...
johnny123's user avatar
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Does a uniform circular disk make a perfect gravitational lens?

I'm surprised at this. I'm expecting to be corrected, but these are my back-of-the-envelope workings ... Starting out with a cylindrical lens oriented along the line of sight. Assuming the cylinder ...
Roger Wood's user avatar
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Gaussian curvature in a weird metric

Consider a disformal metric $\tilde{g}_{\mu\nu}=g_{\mu\nu}+h_{\mu\nu}$, with $g_{\mu\nu}$ being the Schwarzschild metric tensor perturbed by $h_{\mu\nu}$, a generic second-rank symmetric tensor. ...
gangio's user avatar
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What is the gravitational lensing impact on polarity?

Gravitational lens is known for light bending, and gravitation can impact its frequency, but does it any impact on the polarity of this light?
Xavier Prudent's user avatar
4 votes
2 answers
161 views

Momentum conservation in gravitational lensing?

I have read this question: Every time a photon changes direction, it requires something else to gain momentum in the opposite direction, whether a solar sail or a star bending light by gravity. How ...
Árpád Szendrei's user avatar
2 votes
1 answer
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Can gravitational lenses change over human time scales?

Gravitational lensing is caused by the chance alignment of the observer, the lens, and the source. Obviously these are not permanent events as the earth will move in and out of a focal point as the ...
user avatar
7 votes
2 answers
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The effect of gravitational lensing during the lunar eclipse

During the lunar eclipse, the Moon turns into bloody colour while the shadow of the Earth is casting over the lunar surface. The red hue can be explained by means of the refraction of light and ...
Kevin Kwok's user avatar
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Is the speed of light slow down around gravitational body? [duplicate]

In gravitational lensing effect, there are two types of time delay; geometric delay, gravitational delay. gravitational time delay is not caused by "distance", and speed is "distance/...
BAO's user avatar
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Does an accelerated frame of reference have the same effect as that of mass in space time

According to the equivalence principle, gravity and inertial forces are similar. And according to general Relativity, If there’s a large object in space-time, it warps the space time’s geometry and ...
Muhammed Roshan's user avatar
1 vote
2 answers
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Does the gravitational field change in the vicinity of a nova?

Since gravity is calculated based on the product of the masses of two bodies and the distance separating them, I initially thought that the orbits of the outer planets would not be affected when our ...
aquagremlin's user avatar
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3 votes
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If a star gravity can change the apparent location of another star on the sky, can it change the gravitational field vector of that star?

If a star gravity can change the apparent location of another star on the sky can it change the gravitational field vector of the second star? In simple words if a star gravity deflects the position ...
Janko Bradvica's user avatar
2 votes
1 answer
208 views

Formation of a focal point by gravitational lensing effect

Can a black hole form a focal point of a nearby star at a certain distant point by gravitational lensing? Also, can the BH make a virtual picture of that star to a distant observer so the star looks ...
Krešimir Bradvica's user avatar
2 votes
2 answers
189 views

Does the frequency of light have any effect on gravitational lensing? [duplicate]

General relativity considers gravity as the curvature of space-time instead of a force. Therefore, what is bent around an astronomical object is the space-time itself. The light just follows the path ...
Xfce4's user avatar
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What is the photon interception radius of a Schwarzschild black hole? [duplicate]

To clarify what i mean by "photon interception radius" I mean the radius of the sphere where if any photons from a distant source enter will also inevitably result in them entering the black ...
Adam Lincoln Steele's user avatar
2 votes
1 answer
121 views

Light travel time toward and away from a massive object

The curvature of space (or space-time) causes light to follow a curved path. We see this, for example, when we look at an "Einstein Cross" in which light from a distant object, e.g., a ...
Matt's user avatar
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How does the photon interact with the changing spacetime (say when massive object appers nearby)? How does it know how to "bend"?

How does the photon interact with the curved spacetime? Say, we have the photon travelling through the universe. Then it enters the region of gravitatonal lens (or a curved spacetime created by some ...
spsy's user avatar
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Is galactic gravitational lensing self-magnification big enough to contribute noticeably to the galaxy rotation curve problem?

Gravitational lenses magnifies the appearance of themselves, so in the case of a galaxy it looks bigger than it is. Thus the outer stars in a galaxy seems to have a higher tangential velocity. For ...
David Jonsson's user avatar
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1 answer
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Why gravitational lensing appears circular?

I still remember the black hole photo but I know the coffee mug stain is actually the materials orbiting around it appears to be getting pervertedly blended 720 degree around the sphere, but then what ...
user6760's user avatar
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Do gravitational lensing experience Doppler effect?

I watched dark matter explained by Perimeter Institute on YouTube and they used it as gravitational lenses, they also explained Doppler effect so we know how fast things are relative to us. I wonder ...
user6760's user avatar
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1 vote
1 answer
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Are multiple images an exclusive propertiy of gravitational lenses?

Strong gravitational lensing produces multiple images if the object lens and observer are in a specific alignment. This is due to there being multiple stationary points in the time arrival surface for ...
Michkov's user avatar
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5 votes
1 answer
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Can we use curved spacetime to measure the one-way speed of light?

This is related to Measuring one-way speed of light with gravitational lensing and Measuring the one-way speed of light with a black hole? The idea is to shine a beam of light from a clock towards a ...
Whynaut's user avatar
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1 answer
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Can an image formed by gravitational lensing be corrected for the inevitable aberration?

Carl Zeiss would not be impressed with your average gravitational lens. Compared with familar optical lenses that are generally used to form sharp undistorted images, gravitational lenses make quite a ...
Roger Wood's user avatar
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