Questions tagged [gravitational-redshift]

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Experiment on gravitational redshift with receivers at different altitudes

Is there a repeat of the Pound-Rebka experiment on gravitational redshift, where the receiver was placed at two different height distances from the transmitter? What was the result of the experiment?
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Cosmological redshift

We have three of them (and combinations): gravitational, when light travels near masive object (red shift) Doppler's, when light is emited by moving object (red or blue) cosmological - all far ...
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Enquiry about the gravitational redshift in "The young center of the Earth" by U.I. Uggerhøj et al

I was reading "The young center of the Earth" by U.I. Uggerhøj et al., lately, and the standard gravitational redshift equation given in the paper is: The link to the paper: https://arxiv....
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Gravitational redshift work

If you have 2 laser guns that emit a laser at wavelength X and 2 wavelength meters You keep laser gun 1 on the surface of the Earth You bring the laser gun 2 outside the atmosphere Now: The laser ...
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Gravitational red shift and gravitational time dilation

I am a beginner in general relativity. I read the relevant section 9.1.5 in Relativity make relatively easy by Andrew Steane. After that, I thought a problem in gravitational red shift and ...
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If we send a signal to an object closely orbiting a BH would the reflected signal be the redshifted original?

If we send a signal to an object closely orbiting a BH would the reflected signal be the redshifted original? Only that I am sure is that there would be time dilation of the signal...
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Relativistic Redshift and understanding it's approximation

I was reading an article, and I saw the expression $$ 1+z=\frac{(g_{\mu\nu}k^{\mu}u^{\nu})_e}{(g_{\mu\nu}k^{\mu}u^{\nu})_o}, $$ where $e$ represents the emitter frame, $o$ the observer frame, $g_{\mu\...
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How would a person under gravity observe a person on a nearby planet but under 1000 times of that gravity?

So, imagine I am standing in a region in space where the gravity is, say 1g. Now, on a nearby planet, there is my friend who is under the influence of much stronger gravity, like 1000g. According to ...
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When e.g. a star falls into a black hole would that part of the event horizon extend for a while?

When e.g. a star falls into a black hole would a part of the event horizon at that point extend for a while due to extra gravity due to the incomming star? And when the star starts to disappear even ...
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Components in the calculation of the Sun to Earth redshift

When I see calculations of the Sun’s redshift as seen from Earth I believe, as I understand it, that 1) the gravity potential at the emission point near the Sun is taken into account, then 2) the Sun’...
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Why the CMBR redshift is so higher than the redshift of the most distant therefore oldest galaxies in the universe?

Why the CMBR redshift is so higher than the redshift of the most distant therefore oldest galaxies in the universe? We know that cosmological redshift rises with distance from the object but at ...
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Does a blueshift mean that time goes faster?

This is a follow-up question to this answer. The assumption in this answer is that time dilation always causes a small redshift when an observer looks at an object moving at a significant fraction of ...
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Discovery of 3C273 as black holes

In Stephen Hawkings book "Brief History Of Time", in chapter 6 Black holes, on page 102, it is written "He found it was too large to be caused by a gravitational field:if it had been ...
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Do gravitational redshift depends on reference frames?

I just want to know is the effect of redshift depending on the frames of reference or the photon really does lose energy when it escaped from a gravitational well? Imagine a spaceship is shooting a ...
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Clocks in gravitational field

"In a gravitational field clocks slow down" - this is an effect of gravitational redshift. Are the following statements correct? If I take a "clock" from the surface of the Earth ...
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Is gravitational redshift reversible?

Imagine a scenario where a LASER beam is shot from the surface of one planet to a detector on another. Assume there are no atmosphere and nothing affects the beam in any way between the planets. ...
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Can a photon lose all of its energy due to gravitational redshift?

Imagine a photon that is emitted by a star that is at infinity with respect to me. We can observe the gravitational redshift happening to that photon with respect to my reference frame. I was ...
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Do particles at rest gain energy in an expanding universe?

It is commonly understood that as the Universe expands with scale factor $a$ the energy of a photon drops like $1/a$ whereas the energy of a particle at rest is constant. In the analysis below I ...
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Did Chou, Hume, Rosenband, Wineland (2010) account for redshift when analysing their experiment with clocks at varying heights?

In widely reported experiments by C. W. Chou, D. B. Hume, T. Rosenband, D. J. Wineland ("Optical Clocks and Relativity" (2010)) they [...] first compared the frequencies of [their] two ${\...
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What does the $O$ mean in "$O(v^4)$"?

I am currently studying General Relativity and I am using the book by Schutz. I encountered a problem when I was reading about the gravitational redshift experiment. Here is the website (it is not the ...
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Is a star that orbits a black hole, emitting different spectra while close or far from the black hole?

Is a star that is orbiting a black hole emitting different spectra respectively while close and far from the black hole? Also is that star light, when reaching our eyes, some kind of delayed while the ...
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In addition to a cosmological redshift, does the expansion of space cause a gravitational redshift?

Other threads here discuss the increase in gravitational potential energy in the universe due to the expansion of the universe, and the implication of this effect for conservation of energy. My ...
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How the wavelength of a photon is affected by an uniform gravitational field

In the presence of a uniform gravitational field two observers at fixed positions obtain different measurements of frequency of the same photon. One observer at the origin of some coordinate system ...
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Exercise 4, Chapter 6 in Wald's book [closed]

I would like to understand the solution of point b) in the mentioned exercise, which reads Let $(M,g_{ab})$ be a stationary spacetime with timelike Killing field $\xi^a.$ Let $V^2=-\xi^a\xi_a$. a) ...
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Hughes argument (based on Schild's argument) for gravitational redshift

In his lecture notes on General Relativity (2nd page of the pdf, labelled page 7) and in the lecture itself, Scott Hughes puts forward a thought experiment to justify the existence of gravitational ...
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Is energy conserved in a geodesic?

In old school physics we know that Work done (resulf of energy) $=$ Force $×$ displacement. But, according to Einstein, free-fall is not a result of a force but just the result of objects following ...
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Light scattering on the rotating black hole in the Kerr geometry

To simulate light scattering on the rotating black hole we have used this paper and this code. First, we made animation for light beam scattering in the equatorial plane For not equatorial plane the ...
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If an astrophysical jet contains gamma rays does it mean that at the source poles there is small gravitational redshift?

If an astrophysical jet contains gamma rays does it mean that even though the source has incredibly strong gravitational pull, at the source poles there is small gravitational redshift? Maybe there is ...
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Has anyone considered a gradual change in Gravitational Potential across the universe as a cause for cosmic red shift?

Since the formation of fundamental particles at the beginning of the universe (roughly the time of the CMB emission, and after the inflationary epoch of Big Bang theory), the gravity wave front of all ...
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Would light emitted from a white hole be red-shifted or blue-shifted?

if it's not that straight-forward, what factors would effect the resulting appearance of light emerging from a white hole?
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If I live on a planet that is heavy enough, would the CMB get blue shifted to be in the visible spectrum?

If I live on a planet that is heavy enough, would the CMB get blue shifted enough in the atmosphere of this heavy planet, due to gravitational blue-shifting, that the CMB would be in the visible ...
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Gravitational red shift and equivalence principle

Two persons A, B are uniformly accelerating in the positive z direction by amount $g$. $A$ flashes two pulses of light with an interval $T_a$. The time interval between two flashes of light in $A$ ...
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Redshift + Collapse [closed]

Let a radio transmitter on the surface of a collapsing spherical star emit monochromatic waves, let the distant observer, at the same theta and phi, as the transmitter, receive the waves. Show that at ...
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Mössbauer effect to verify the gravitational redshift

"The tower used by Pound and Rebka in 1960 to exploit the Mossbauer effect is only about h = 20 meters high, and so the effect (gravitational redshift) is only $(GM/(Rc^2))(h/R) ∼ 10−15$! How ...
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Does matter redshift light via gravity?

Imagine a photon passes by a stationary atom in a large void of empty space. We know that the gravity of the atom will bend the path of the photon. It will also blue shift as it approaches the atom ...
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Gravitational redshift in terms of wavelength

I know that Einstein’s theory of general relativity predicts that the wavelength of electromagnetic radiation will lengthen as it climbs out of a gravitational well. Photons must expend energy to ...
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Does the Hubble law make sense?

The Hubble law says that if an object is at a distance $r$, it should have a velocity $Hr$ and therefore any light signal from that object will be correspondingly redshifted. However, the light ...
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How accurately has general relativity's prediction of gravitational redshift been measured?

According to Einstein's general relativity, massive bodies should cause gravitational redshift. How accurately has this been measured?
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Is color perception of an celestial object effected by red shifting?

Assuming I stand on the edge of the gravitational well formed by our Sun. If I was to move infinitely closer to the Sun- and was staring at it without a filter (and wasn't harmed in doing so)- would ...
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What is the frequency of a freely falling light-source measured by observer standing on planet?

Assume that a light source is falling freely on a planet with a nearly uniform gravitational field. If the light source, reaching a velocity $v$, emits a photon towards an observer standing on the ...
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Is this anomalous phenomenon about the gravitational blueshift effect experimentally tenable?

According to relativity [1], if there is a light source $B$ with a frequency $\nu_B$ at a distance $d$ from an observer $A$ inside a uniform gravitational field of $g$, the frequency of the light ...
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What is the effective radius of stellar graviton emission?

White dwarfs have been used to accurately determine photon gravitational redshift:https://scholar.google.co.uk/scholar?as_ylo=2016&q=white+dwarf+gravitational+redshift&hl=en&as_sdt=0,5#d=...
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Is Eddington Luminosity at event horizon infinite?

I was reading up on a paper here. Where the author asserts that relativistic form of Eddington limit as defined in his earlier paper should be this, which is: $L_{ed} = \frac{4\pi G M_{x} c }{\kappa}(...
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Do we have to observe gravitational red/blueshift from a single frame?

I have read this question. Gravitational redshift and Energy of a photon In the answers and the comments it states that the redshift/blueshift has to be observed from the same single frame. It says ...
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Calculation regarding redshift and black hole

Reading this entry: http://www.scholarpedia.org/article/Bekenstein_bound I was wondering about one calculation mentioned. They say an object that descends adiabatically to almost a black hole's ...
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Does gravitational red shift test the equivalence principle or general relativity?

These comments seem to say gravitational redshift experiments would only verify theories that obey the equivalence principle (ep), not specifically general relativity: https://arxiv.org/abs/0806.0528 (...
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Is the GW170817 event evidence or counter evidence for Dark Energy?

I've always figured there must be a simpler explanation for the observed lack of red shifting that has lead astronomers to hypothesize Dark Energy. Or at least there must be a simpler explanation of ...
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How is the global time coordinate $t$ ("observer at infinity" time) defined operationally e.g. in the Schwarzschild metric?

This is a question about coordinate time versus clock time / observed time, which I want to understand because I am teaching a GR course. Consider the Schwarzschild metric for specificity. I ...
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Gravitational Redshift

I want to calculate the gravitational redshift for schwarzchild spacetime. If we take the emitter(source of light) and observer stationary, how can be redshift found? Frequency seen by observer : $w=-...
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Black hole, gravitational redshift, Doppler effect

I'm studying up on the physics around black holes and got myself confused with the concepts of gravitational redship and Doppler effect. Imagine a spacecraft orbiting a non-spinning black hole. It ...
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