Questions tagged [redshift]

Redshift refers to the difference in frequency of an electromagnetic wave as measured by a source versus a receiver in relative motion.

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Are Photons Entangled with Gravity? [closed]

Part 1: A photon's wavelength is red-shifted by expanding space. Since $E=hf$ the photon imparts some of it's energy to the curvature of space, slowing the expansion of space ever so slightly. Is that ...
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How can you determine distances to obejcts further away than 13.72 billion light years?

I was checking out this calculator where you can calculate distance to distant astronomical objects from redshift. Here are some values: z=0.1 > distance (light travel time) 1.31 billion lightyears ...
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Why galaxies with a redshift > 2 have a lower velocity now, compared to when the light was emmited?

I was playing around with astropy cosmology data, and I made the following graph: On the x axis I plotted Redshift, and on the y axis the speed of light as 1c, 2c etc. Until a redshift of ~ 2, my ...
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Is photon redshifted if observer starts moving away after photon is released

A. A light source and an oberserver are stationary relative to each other. The source emits a photon and the observer measures the wavelength. B. A light source and an observer are stationary ...
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Hypothetically, according to the Standard Model, if the universe were not expanding, could we not cut out the Big Bang and inflation?

Hypothetically, according to the Standard Model, if the universe were not expanding, could we not cut out the Big Bang and inflation and begin the universe in an expanded state and still get the same ...
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Redshift and luminosity

Consider a flat FLRW Universe where the scale factor is $a = (t_0/t)^{2/(3+3w)}$. For a given redshift $z$, in which universe, $w=0$ or $w=1/3$ would a star appear brighter? I am trying to solve this ...
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Too many low redshift galaxies in NED database

When using the NED database I found there are too many galaxies with very low redshift (Near zero). I used NEDs search by parameters function to find all galaxies within Z=0 to Z=.03 redshift. I did ...
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Proof of double Doppler shift

We know that the Doppler effect for EM radiation is $\Delta$$f$ = $\frac{v}{c}$$f_0$ $\Delta$$f$ = the change in frequency v = the relative speed of the source and observer c = the speed of light in a ...
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Supernova Observation and Hubble Parameter

“Their observations measured the evolution of the Hubble parameter over time by constructing a Hubble diagram: a plot of distance modulus versus redshift (Figure 11.33). For small $z$, the Hubble ...
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Is gravitational redshift measurable from a spacecraft observing an earthbound laser?

Aside from the calculation, the specific scenario for which I have no sense of the solution is the following: The equivalence principle proposes a parallel between the force experienced by an ...
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Cosmological redshift in static universe [duplicate]

Can cosmological redshift be explained in a static universe?
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Would a telescope travelling at close to the speed of light be able to make better images because the object would be nearer (Lorentz contraction)?

The Lorentz contraction means that when you fly toward (or away from) a distant object, that object becomes less distant in your frame of reference. So if a telescope were flying towards a distant ...
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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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What's the definitive meaning of "redshift", as a quantity to be measured? [closed]

The recently supplied tag information on redshift states: "Redshift typically refers to the difference between the frequency of an electromagnetic wave as ...
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How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other?

How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other? So is it possible that gravity accelerates light? Can the a certain wavelength ...
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How do we observe redshifted light from distant stars if the effect is not intrinsic to photons?

Derek from Vertasium says that wavelength and energy are not intrinsic properties of photons; they are properties of the photon-observer system. An observer in freefall in space will not observe ...
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How to account for signal transmission in measurements of beat frequency between separated senders?

An important technique in optics experiments is the determination of the beat frequency (a.k.a. beat note) between (optical, as good as monochromatic, suitably stable) signals of two senders; say, of ...
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Cosmological energy conservation

The expanding universe is gaining energy through increasing dark energy, and losing energy from red shift. Are these two effects comparable in magnitude?
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Where can I find redshift data?

Is there any database for redshift data of individual galaxies and stars for a long period of time?
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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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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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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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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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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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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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