Questions about properties, dynamics and phenomenology of cosmic strings and superstrings.
Questions tagged [cosmic-string]
46 questions
9
votes
1 answer
Can a cosmic string pass through the earth undetected?
The metric around a straight, static and infinitely long cosmic string is flat except for the topological deficit in the angular coordinate, as described for example here. As a result, there is no gravitational force on surrounding matter. The…
J. Delaney
- 2,680
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7
votes
0 answers
Are cosmic strings related to string theory?
In a recent video by Sabine Hossenfelder (link), she said that cosmic strings are strings (from string theory) that have grown to galactic sizes from the time of the early universe. This surprised be a bit because I previously heard that the two…
Steerpike
- 191
6
votes
1 answer
Why is general relativity in (2+1) dimensions different from cylindrical systems in (3+1) dimensional GR?
The gravitational potential $\Phi$ of an infinite rod in newtonian gravity is $\Phi \sim \ln(r)$. This is the same as the gravitational potential of a point charge in two-dimensional Newtonian gravity (see…
asmaier
- 10,250
6
votes
1 answer
Does Goldstone theorem have anything to do with Cosmic string
Cosmic strings are formed due to topological defects during symmetry breaking phase transition in early universe.
While Goldstone theorem states whenever we have continuous symmetry and it is spontaneously broken then we have scalar particles…
aitfel
- 3,123
6
votes
3 answers
What's the connection between cosmic strings and the strings hypothesized in string theory?
I read somewhere that Edward Witten, the (once) big hotshot of string theory, said that the discovery of cosmic strings (at the beginning of this Wikipedia article it is written: "Not to be confused with strings in string theory") would provide…
Deschele Schilder
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5
votes
3 answers
Attraction near a straight cosmic string
I'm having an interpretational issue with the particles behavior around a straight cosmic string.
Consider the infinite cylindrical universe described by the following metric:
$$\tag{1}
ds^2 = dt^2 - dr^2 - (1 - 4 G \mu)^2 \, r^2 \, d\varphi^2 -…
Cham
- 8,015
5
votes
1 answer
Gravitational lensing and cosmic strings
Say we have a straight cosmic string lying along the $z$-axis, with energy-momentum tensor
$$T_{\mu\nu}=\mu\delta(x)\delta(y)\operatorname{diag}(1,0,0,-1)\tag{1}\label{1}$$
for some small positive constant $\mu$. In the linearized Einstein theory,…
Demosthene
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3
votes
1 answer
Cosmic strings increasing internal energy as the Universe expands?
I was reading an article by Edward Harrison, which tackles the problems of conservation of energy at cosmological scales.
At some part (point 2.4) he cites several article, including one by Rees and Gott, which he says indicates that the internal…
vengaq
- 3,282
3
votes
1 answer
Gravitational attraction/repulsion of cosmic strings and domain walls
It is well known that straight static cosmic strings don't produce any gravitational effects on test-particles, and that static flat domain walls are repulsive. This can be seen from the linearized theory of Einstein's equation, in the case of…
Cham
- 8,015
3
votes
1 answer
Cosmic strings and ground state degeneracy in SSB
There are two conflicting perceptions that I have regarding the notion of ground state post-SSB. Consider the Higgs mechanism e.g. for the electroweak theory.
On the one hand, we say that the vacuum manifold is just a redundancy: all sectors are…
Yoni
- 735
3
votes
0 answers
Candidates for cosmic strings
What are the observed candidates for cosmic strings (or other defects), that are not ruled out? With references if possible.
Kosm
- 2,756
3
votes
0 answers
Basic question on Cosmic Strings
What is the typical size of Cosmic String Loops?
If a loop is formed today, what are the restrictions on its size?
I would like to know if there is a distribution of cosmic strings depending on its radius. Is such a distribution valid for loops that…
negligible_singularity
- 319
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2
votes
1 answer
Cosmic Strings as Topological Defects (heuristics)
I have a lot of troubles to understand heuristically the principle behind Kibble's model for genesis of cosmic strings via Kibble mechanism. More precisely I not understand how to interpret following two pictures I found here:
Prelude: We start…
user267839
- 1,711
2
votes
1 answer
Understanding the units of cosmic string number density
I am reading this old paper: https://arxiv.org/pdf/1309.6637.pdf and trying to work out the units in equation 63. It gives the number density of cosmic strings in the radiation era as
$$
\frac{n(\ell,t)}{a^3(t)}\approx\frac{0.18}{t^{3/2}(\ell+\Gamma…
user3517167
- 150
2
votes
0 answers
Energy density of a cosmic string in the Abelian Higgs Model (Nielsen-Olesen Vortex)
my question is what the energy density of a cosmic string in the abelian higgs model is? I have different sources (Scholarpedia Cosmic Strings, the book "Cosmic Strings and Topological Defects" from Vilenkin and Shellard, etc.), but they all give…
Luis
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