Questions tagged [cosmology]
The study of the large-scale structure, history, and future of the universe. Cosmology is about asking and answering questions about the "big picture" - the extent, origin, and fate of everything we know.
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Viable values for the 'K' parameter in the FLRW metric
The FLWR metric is sometimes given as $$c^2 d\tau^2 = c^2 dt^2 - \frac{a(t)^2}{(1-Kr^2)} dX^2. $$
I am not interested in the tangential motion so I set $d \Omega = 0$ although it is of interest in ...
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Title: Novel Theory: Dimensional Escalation, Hyper Dimensions, and Multiverse Energy Balance [closed]
Title: Theory of Dimensional Escalation, Hyper Dimensions, and Multiverse
I have developed a theory regarding dimensional escalation, hyper dimensions, and the multiverse, and I would greatly ...
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Cosmological numerical computations
I am unsure where to ask this question, whether here or in the Mathematica stackexchange, but either way, I was wondering what are some recommendations for cosmological computations specifically using ...
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Can a light signal from Earth reach a galaxy outside the Hubble Horizon?
Is this video on the FLRW metric (timestamp 19:00 minutes) mistaken in its claim that a light signal from Earth cannot catch up with a galaxy outside the Hubble horizon, due to the horizon receding at ...
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Is the FRW metric, based on spatial homogeneity and isotropy, rotationally and translationally invariant? If so, how?
The spatial part of the Minkowski metric, written in the Cartesian coordinates, $$d\vec{ x}^2=dx^2+dy^2+dz^2,$$ is invariant under spatial translations: $\vec{x}\to \vec{x}+\vec{a}$, where $\vec{a}$ ...
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Gravitational halos made of neutrinos...?
I have been recently interested in how halos made of standard model particles could be formed and behave.
After asking some questions in this site, I was told about how neutrinos could form such halos....
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What is the energy density of gravitational fields around neutron stars? [closed]
The field strength of gravitational fields around neutron stars is extremely high. This would lead to an extreme negative value for the energy density. But if an absolute negative energy density is ...
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Why can we use Bose-Einstein statistics in this expression for number density
In a system with $N$ particles in some volume $V$ in contact with a reservoir of temperature $T$, we find that
$$\bar{n_i}=\frac{g_i}{e^{\frac{{\epsilon}_i -\mu}{kT}} \pm 1}$$
depending on whether the ...
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The data file of the LISA Interferometer results
How to extract the data of the strain versus frequency plot of the Laser Interferometer Space Antenna (LISA): Figure (2) in this paper:
https://arxiv.org/abs/1702.00786
The paper doesn't contain any ...
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Magnetic monopole in CPT universe model
I've recently read this paper CPT universe, and a thought came into my mind.
Is it possible to discuss magnetic monopole based on this CPT universe model?
This paper points out that some mysterious ...
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Saddle Shaped Universe
The universe, as described by FLRW metric, if $k = -1$ is clearly a 2 sheet 3-hyperboloid described by $x^2+y^2+z^2-w^2=-R^2$. So where does the more common saddle shaped picture of the open universe ...
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How can I visualise a sphere with a negative radius? [closed]
I want to visualise the shape of the sphere , will having a negative radius turn the inside of the sphere outside or something other will happen ?
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Beginning of a dark energy (cosmological constant) dominated universe
Consider a flat universe with only dark energy (cosmological constant)
In such universe, the Friedmann Equation can be written as:
$$H(t)^2 = \left(\frac{\dot a}{a}\right)^2 = \frac{8\pi G \...
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