Questions tagged [redshift]

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Wouldn't Miller's planet be fried by blueshifted radiation?

In Interstellar, wouldn't Miller's planet be fried by blueshifted radiation? The 61,000x time dilation multiplier would make even cosmic background radiation photons into extreme UV photons. I was ...
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1 vote
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Which are the spectral lines used to calculate the redshift?

I'm not sure if this is correct but I read in an article that the light of a distant star is first passed through a tube containing hydrogen gas and then through the prism for getting the absorption ...
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0 votes
1 answer
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How is the light from distant stars obtained on a prism for calculating redshift?

Redshift has been used to map the expanse of the universe but what mechanism do scientists use to obtain and single out the light from a galaxy millions of light years away on a prism for getting the ...
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-1 votes
0 answers
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Relativistic doppler redshift

From Wikipedia I can only find "longitudinal" and " closest approach" redshift. I was wondering what resources I can use to find the redshift (and resulting energy change) of ...
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2 votes
4 answers
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Is it possible to visualise red shift?

If a picture of a star or galaxy hurtling away from Earth is taken, does it appear red despite it being a different colour? Would a blue coloured star moving away from us appear red to us or vice ...
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2 votes
1 answer
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Is redshift an accurate method for measuring distances of distant galaxies and quasars?

I'm currently in 11th grade working on a science project about measuring distances using redshifts. I understand how the wavelength of a light wave increases when an object moves away from the point ...
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1 vote
0 answers
55 views

Why is the age of the universe $=D/v$, despite that $v$ is not constant with time?

I am watching a series of lectures by the Noble prize laureate Brian Schmidt and Paul Francis and in this episode (at 4:20) they make the simple assumption that a galaxy receding from us due to the ...
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Does the relative speed of light, or just the frequency of light, change near a planet?

I have read this this question that describes the red shift in frequency of light near a large planet. I'm wondering if the light will actually reach me slower. Imagine that we have two lasers 1,000,...
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-3 votes
1 answer
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What is the “conspiratorial anisotropy” if we would see no star redshifts in one direction of the sky? [closed]

Suppose we see no redshift of stars in one direction only (or better, in directions on a small patch around it). And suppose in that direction (on a patch of sky around it) we see a lot more stars ...
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10 votes
2 answers
646 views

Mass of cosmologically distant object in Earth frame

The original paper on GW 150914 in PRL 116,06112 (2016), talks about black hole masses in the source frame and the detector frame, indicating that the black hole masses in the detector frame are ...
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0 votes
1 answer
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How to calculate the redshift of reionization?

I am trying to calculate equalities given Omega parameters. For example given, $\Omega_L = 0.6889083, \Omega_M = 0.311, \Omega_R = 9.17$ x $10^{-5}$ and $\Omega_K = 0$ $H_0 = 67.7$ km/sec/Mpc The ...
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Observed redshift changes at a rate

I'm having a bit of trouble showing that in a flat, single component universe, the redshift changes at a rate modeled by $$\frac{dz}{dt_0}=H_0(1+z) - H_0(1+z)^{3(1+w)/2}$$ My current steps involve the ...
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-2 votes
1 answer
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Redshift Due to Expanding Space (not increasing distance) [closed]

Please NOTE: "For example, a question that proposes a new concept or paradigm, but asks for evaluation of that concept within the framework of current (mainstream) physics is OK." And: "...
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1 answer
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Cosmological time-dilation caused redshifting and photonic energy: Are Photon’s Energies Changed by Relativistic Transformations?

Amateur here, so go easy. Given that cosmological time-dilation is the only GR-consistent reading of cosmological redshifting due to the accelerated expansion of space (due to the constancy of the ...
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0 answers
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Do we see the fluctuations of the CMBR slowed down by a factor of 1100?

Do we see the fluctuations of the CMBR slowed down by a factor of 1100? If redshift streches the signal like a spring it should last longer in our eyes and by a factor of 1100 so every change in the '...
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1 vote
0 answers
35 views

Could gravitational waves be cosmologicaly 'redshifted'? [duplicate]

Is it posible that gravitational waves detected here on Earth could be cosmologicaly 'redshifted'? So, at emission they had higher frequency then after reaching Earth?
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0 votes
2 answers
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Does dark energy redshift over time?

In the expanding universe, light is subject to redshift. Does redshift also affect dark energy - and why?
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1 vote
1 answer
54 views

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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If the redshift of CMBR is 1100 is then possible find an object as a protogalaxy at e.g. redshift 100?

If the redshift of CMBR is 1100 is then possible find an object as a protogalaxy at e.g. redshift 100? If the telescope 'James Webb' can 'look' very far should it detect some very distant objects ...
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0 votes
2 answers
58 views

If gravity interacts with light just by changing the wavelength of light why a BH does not emit EM-waves even of extremely low frequencies?

If gravity interacts with light just by changing the wavelength of light why a BH does not emit EM-waves even of extremely low frequency? A neutron star does the gravitational redshift of light but ...
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0 votes
1 answer
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If the BH accretion disk rotates near the speed of light should its EM-radiation in direction of rotation be highly blueshifted?

If the BH accretion disk rotates near the speed of light should its EM-radiation in direction of rotation be highly blueshifted? Maybe gamma blushifted if there weren't gravitational redshift?
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0 votes
0 answers
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Would a supernova 1A appear to last longer if it were more distant and does it depend linearly on measured cosmological redshift?

Would a supernova 1A appear to last longer if seen more distant and does this depend linearly on measured cosmological redshift? I asked a question on a very popular radio station where they talked ...
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1 vote
2 answers
36 views

When we measure our distance from a very distant astrophysical object image do we input its past location and our present location?

When we measure our distance from a very distant astrophysical object do we input its past location and our present location? Please take a look on the picture where our past location is A1 and the ...
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0 votes
2 answers
61 views

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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1 vote
1 answer
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If cosmological redshift causes wavelength elongation does it mean the whole emitted signal is elongated?

If cosmological redshift causes wavelength elongation does it mean the whole emitted signal is elongated? Let say we have ten waves on the see hitting the shore.... If we somehow elongate every single ...
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0 votes
0 answers
31 views

Expansion speed of the universe in the interval between Big-Bang until first galaxies, and in the interval between first galaxies and 'now'

If the redshift or elongation of microwave background radiation is about 1000 times and the redshift of light of the most distant galaxies which are the oldest ones in our Universe is only about 10 ...
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1 vote
1 answer
39 views

Where can I find redshift data?

Is there any database for redshift data of individual galaxies and stars for a long period of time?
1 vote
3 answers
110 views

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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1 vote
0 answers
43 views

How is the expansion of the universe measured if redshift depends on the expansion itself? [duplicate]

To me this seems like a bit of a chicken egg problem. Based on the redshift of light (plus the assumption that physics worked the same way back then and there as it does now and here), we can ...
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0 answers
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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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-4 votes
1 answer
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The “Wave Function” of QM and Cosmological Redshift—An Inconsistency In Physics? [closed]

Take the archetypal quantum event—the emission of a photon by an atom, and its propagation through space until absorption by another atom. Assume the emitting atom be one near the edge of our ...
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0 votes
0 answers
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Can we tell the difference between the redshift of light off a moving mirror (from a moving galaxy)?

Assume there is a mirror placed 1 G light year away. Because of the universe expansion, the light shine on it will have redshift when reflected (I assume this, correct me if I am wrong). Image there ...
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1 answer
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Does Hawking radiation from micro black hole get redshift like it stellar counterpart?

In a stellar black hole the hawking radiation gets redshift as it escapes the event horizon, would the same phenomenon occurs with a micro black hole? If so what is the threshold for the redshifting ...
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0 votes
1 answer
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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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3 votes
1 answer
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If you travel fast enough towards a light source, will you fall into a kugelblitz?

A kugelblitz is simply a special case of black hole, one that's formed from photons instead of fermions. Thanks of course to mass-energy equivalence, enough photon energy in a small enough region can ...
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2 votes
0 answers
70 views

Transverse Doppler Effect In Special Relativity [duplicate]

Based on the Wikipedia article for special relativity: It shows how light is red or blue shifted based on whether the observer is moving or the source is moving. I'm having a hard time understanding ...
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0 votes
1 answer
49 views

Taylor Expansions in Derivation of Gravitational Redshift in weak field limit

In general, the redshift of a photon emitted from one static observer at point $A$ to another static observer located at point $B$ is of the form $$ z_{AB} = \frac{\omega_A}{\omega_B} - 1 $$ where $\...
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4 votes
3 answers
759 views

Does GR explain cosmological time dilation?

There is plenty of evidence for a cosmological time dilation effect. For instance a supernova that takes 20 days to decay will appear to take 40 days to decay when observed at redshift $z=1$ (see Ned ...
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1 vote
4 answers
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A star is just born and starts travelling towards us at 99 percent speed of light. So how would an immortal observer observe the light from it?

An immortal observer is observing a new born star from billions of lightyears away travelling towards it at near the speed of light (99%). The star is a short living one and dies soon before reaching ...
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0 votes
1 answer
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Black hole falling observer blueshifted light

As per chapter 7, figure 8 Link from Exploring Black Holes, 2nd Edition for a falling (rain frame) observer dt(reception) of light pulses sent from far away one second apart is greater than one second....
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1 answer
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Momentum and energy of photon

Does the momentum and energy of photon change when it travels from distant galaxies through the Space?
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2 answers
48 views

Does Redshift depends on wavelength?

I came across this equation on Wikipedia: $$z=\frac{\lambda_{\text{observed}} - \lambda_{\text{emitted}}}{\lambda_{\text{emitted}}}$$ and it got me thinking: If I measure a wavelength of $700 \;\text{...
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1 vote
1 answer
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Is red-shifting the only proof for the expansion of the universe?

Are there other proofs for the expansion of the universe other than red-shifting? If yes, what are those? Thank you.
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16 votes
1 answer
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Galaxy getting closer faster than light

In cosmology, we speak of galaxies racing away from us due to the expansion of the universe. The light from these galaxies appears red-shifted. If the galaxies are far enough, then the space between ...
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0 votes
1 answer
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Redshift graph of Type Ia supernova: Two case

The redshift graph obtained from a well-known supernova study appears in two cases in Google search. When I find the relevant data, regardless of whether the y-axis is set to distance or grade, the ...
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0 votes
0 answers
26 views

Gravitational and cosmological redshifts

Light that we receive today from a far-off galaxy originated in the past when universe was much smaller. If we approximate the universe to be a sphere, light originated from a much smaller sphere with ...
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-2 votes
1 answer
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Redshift is same as Doppler effect in sound ? if not how different it is?

Is redshift same as doppler effect in sound ? if not what makes it different ?
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1 vote
3 answers
93 views

Can cosmological redshift only decrease photons' energy by increments (that correspond to Planck's constant)?

I have read this question: The equations that govern quantum mechanics predict that the angular momentum (that is, spinning or orbiting) in a system can't take on any value, but instead come in lumps....
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2 votes
0 answers
49 views

Does the cosmological redshift of the same object has a same value as it evolves

https://arxiv.org/abs/1802.02444 According to the link above, the following phrase comes out: " One must keep in mind that in the real universe, the same object( or comoving position) does not ...
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8 votes
5 answers
1k views

Is there cosmological redshift within the Milky Way?

Cosmological redshift is based on the idea that the universe is expanding. When the universe doubles in size, or scale factor, the wavelength of light doubles. But the Milky Way is not expanding so my ...
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