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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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 ...
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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 ...
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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 ...
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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 ...
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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(...
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Given the gravitational lens, how do we actually know where stars/galaxies are actually located?
Hobby physics newbie at best...
Given that we know that gravitation bends light and we even use that to phenomenon to observe distant stars (gravitational lens). How do we actually know where a ...
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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 ...
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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://...
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Gravitational lensing lens to source distance
So the Einsteins ring is given by $\theta_E = \sqrt{\frac{4GM}{c^2}\frac{d_{LS}}{D_L d_S}}$, and all textbook emphasizes $D_{LS} \neq D_S - D_L$, then how do we determine $D_{LS}$ ?
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At what scale would the metric expansion of space have an observable effect on objects bound by gravitational forces?
Elsewhere on this exchange it has repeatedly been asked in what ways metric expansion manifests in objects bound by forces, and has been answered as such objects experienceing a negligible increase in ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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?
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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 ...
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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 ...
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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 ...
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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/...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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Why a gravitational lense makes multiple distinct pictures of a distant object rather than making a symmetric ring?
I cannot imagine how a group of galaxies may produce pictures of a distant object on a ring-like region that is not symmetric. Why there are empty parts of that ring where there are no pictures of the ...
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Is polarization of light preserved in gravitational lensing?
Space should not have torque since the stress energy tensor is symmetrical. That would imply that gravity can not turn a polarization plane of an electromagnetic wave. Have any changes of ...
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Plausibillity of using a black hole as a telescope?
I recently learned about the proposed FOCAL telescope, which would use the Sun's gravity as a lens to observe exoplanets (or whatever it's aimed at) with incredibly high resolution. Obviously, the Sun ...
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Observing starlight bending in high gravity
I note that there is a fair amount of light-bending questions, but I don’t really see the observer effect I am asking about. I apologize there is an answer already.
I wonder if the Earth’s gravity – ...
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Gravitational lensing: derivation of magnification
In gravitational lensing, the image magnification is defined as the image area over the source area. But many texts also give it as the inverse of the determinant of the jacobian, A, of the of the ...
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Measuring one-way speed of light with gravitational lensing [duplicate]
This recent video from Veritasium (https://youtu.be/pTn6Ewhb27k), explored the problem of measuring one-way speed of light and covered a few possible (and practical) solutions. However my ...
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How much energy from the Sun could we get if we use Jupiter as a gravitational or atmospheric lens?
How much energy (watts) from sunlight could arrive to the focal point if we use Jupiter as a gravitational lens? and if we use it as an atmospheric lens by using refraction?
How far the focal point ...
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Do gravitational lenses act as prisms?
Light creates gravity, and the greater the light's frequency, the greater this gravitational effect is. It stands to reason then that light of different colors would react slightly differently to ...
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Axially Symmetric Lens Integration
I'm trying to understand the deflection of light due to an axially symmetric gravitational lens following chapter 2.3 of these Heidelberg lecture notes. In doing so, I encounter the integral (2.12 a)
$...
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Are gravitational waves subject to gravitational lensing? [duplicate]
Can gravity be focused by large massive objects?
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