Questions tagged [cosmological-horizon]
Questions about the size of the observable universe.
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Entanglement in- and outside the observable universe
Consider the limit of the observable universe.
Assume we received and analysed a photon coming from a distant region close to the edge of the observable universe.
If we believed - based on energy ...
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Is Webb or any near-future telescopes like ELT capable of observing redshift changes to confirm General Relativity?
The (Davis and Lineweaver (2003)) "Expanding Confusion" paper states that "the expected change in redshift due to cosmological acceleration or deceleration is only ∆z ∼ 10^(−8) over 100 ...
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Conditions in the Early Universe
I am interested in how the large-scale properties of the Universe change over time.
Does anyone know a trusted website which gives the temperature, density and radius (distance to the particle horizon)...
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What equation tells you how far in space you can go from a point and return?
We know that hubble expansion increases the distance between points in space, and that the cosmological event horizon represents the distance from the observer at which objects are receding faster ...
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Size of the whole universe if it were spherical
Suppose the universe is spherical and its density ratio is
$\Omega \leq 1.00125$
$\Omega = 1.00125$ is approximately the maximum possible value of the density ratio according to the Planck Mission ...
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Minimum redshift for galaxies receding $\geq c$ when light transmitted
What is the minimum redshift for galaxies receding $\geq c$ when light was first transmitted that are visible today from Earth? Is that value the same as maximum angular size distance?
This question ...
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Is it possible to infer information about the structure of the universe beyond the observable one?
Is it possible to infer information about the structure of the universe beyond the observable one, by observing its effects on the parts we can see? Can for example gravity from sources we cannot see ...
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Objects beyond 13.3 billion light-years away are (apparently) moving away from us at faster-than-light speeds? [duplicate]
That is, if you use the cosmic distance ladder method, and a value of about 73.5 for the Hubble constant....
But, if you plug in the Planck CMB value of about 67.5, you get a distance of about 14.5 ...
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How do you calculate comoving distance and light's travel distance? According to the formulae below?
According to Wikipedia, Distance measures (cosmology),
Comoving distance:
$${\displaystyle d_{C}(z)=d_{H}\int _{0}^{z}{\frac {dz'}{E(z')}}}$$
Light-travel distance:
$${\displaystyle d_{T}(z)=d_{H}\int ...
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Transverse Comoving distance
I don't understand the link between the comoving distance and transverse comoving distance : how can they be equal ?
Here an example of definition that I have found :
Angular Diameter Distance :
The ...
user16492
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What's the furthest distance that something could travel and eventually come back to Earth?
Imagine u shoot a photon into the sky at a mirror far away in space, and you want the photon to bounce off the mirror and eventually come back to you. Considering the cosmological constant, what's the ...
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Clarifications about distances in cosmology
I would like to get clarifications about some usual notions of distances in cosmology.
First, is the comoving distance the current distance of objects whose light has been reached by us now, i.e. ...
user16492
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How far away are objects whose light will never reach us, because of the expansion of the universe?
I thought I had read this question on Stack Exchange before, but now I cannot find it... In fact, I thought I had posted this question before, somewhere, on Stack Exchange...
I believe the answer ...
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Must time pass more slowly, relative to our inertial reference frame, inside galaxies that are currently located at half way to the Hubble Horizon?
Trying to understand simultaneity of events and time-dilation on a Universe scale, I would like to know must time pass more slowly, right now, relative to our current inertial reference frame, inside ...
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Expresion of comoving distance
I have a simple question :
How to prove the following relation :
The comoving distance to an object at redshift $z$ can be computed as
$$r(z)=\dfrac{c}{H_{0}} \int_{0}^{z} \dfrac{\mathrm{d} z}{E(z)}$...
user16492