Questions tagged [singularities]

Use this tag for questions about singularities in physical quantities, i.e. cases where a quantity becomes or appears to become infinite or ill-defined. Consider the more specific tags [tag:black-holes] and [tag:wormholes] for certain kinds of singularities occuring in [tag:general-relativity]. For the procedure of "getting rid" of singularities, consider [tag:regularization].

77 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
1
vote
1answer
516 views

Electric field at $r=0$

How does classical physics justify the existence of an electric field at $r=0$? Is this an edge case, an ambiguity, a "does not exist"? Is this a trivial case or indicative of an actual fault in ...
0
votes
1answer
257 views

Finding the maximum value of electric field

Suppose you have a surface of finite area with a fixed surface charge distribution. Does a maximum electric field magnitude $|\vec{E}|_{max}$ exist for each and every possible surface area? If yes, ...
0
votes
0answers
31 views

What happens to renormalisation counter-terms in the classical limit?

My understanding is we add counter-terms to the actions in the process of renormalisation. Presumably these terms don't have a physical effect in a classical interpretation of the action. i.e. they ...
0
votes
0answers
32 views

What happens when a black hole evaporates?

I have read other articles here on the subject and I think my question is different.. When a singularity evaporates enough to reach just above the limit of mass required to make the singularity, what ...
0
votes
1answer
62 views

Curvature scalars and singularities

Without resorting to the singularity theorems, can we say that there is a singularity at a particular $r=\textrm{constant}$ if the value of the Ricci and Kretschmann scalars get infinitely large at ...
0
votes
0answers
72 views

AdS/CFT correspondence and gravitational singularities

While Einstein‘s equation breaks down at singularities, the question arises: which statements/answers can be provided by the corresponding conformal field theory (CFT) in this case?
0
votes
0answers
62 views

Why is the singularity not taken into account?

In this article "Reflections on Maxwell’s Treatise", Section 4.2, it says: He replaces $\mathbf{m}$ with a volume element of magnetization $\mathbf{M}\ dV$ , integrates over $V$ , and lets the same ...
0
votes
0answers
34 views

singularity blow up in supersymmetric theories

I have been doing some reading on algebraic geometry, in particular singularity resolutions. All the examples I am familiar with in physics correspond to singularities of the extra dimensions (e.g. ...
0
votes
1answer
38 views

Moving singularities

I am aware that black holes can move through space-time. Is there a way to move a naked gravitational singularity artificially? Sorry if this is a little stupid, trying to figure out the feasibility ...
0
votes
1answer
75 views

Electric field at source points of any continuous charge distribution

In classical electromagnetism, is there a way to find the electric field at source points of a line, surface or volume charge? If there is a way, please explain in detail My idea: I don't really ...
0
votes
0answers
59 views

Are singularities' behaviour really unpredictable?

If a real/true singularity existed our models and theories would become useless to predict what would happen in that singularity. For example if naked singularities really existed, we could not ...
0
votes
2answers
89 views

How to plot the graph of this expression which involves Dirac delta function?

I was doing a problem on electrostatics which required finding the charge density from the given electric field and then plot a graph of the charge density. I was able to find the charge density which ...
0
votes
1answer
72 views

Does metric stretching show up in all coordinate systems?

The radial component of the Schwarzschild metric shows a dramatic metric stretching as the event horizon is approached from the outside and it shoots to infinity at the horizon. Does this extreme ...
0
votes
1answer
29 views

Semiclassical propagator convergence at $t=0$

For harmonic oscillators the prefactor for the semiclassical propagator is $Fe^{iS}$ where $$F=\sqrt {m\omega/{2πi\hbar\sin(ωt)}}$$ and $$S={m\omega[(x_0^2+x_1^2)\cos(\omega t)-2x_0x_1]}/{2\sin(\omega ...
0
votes
2answers
70 views

Can there be a Singularity Knot?

On studying the pictures representing the warping of space-time due to Black Holes, I realised the denser the black hole is the shorter its Event Horizon becomes, can we reach a point where we would ...
0
votes
1answer
115 views

Worldsheet metric & event horizon

Given a certain metric $g_{\alpha \beta}$ (not necessarily diagonal) in which $g_{\tau \tau}=0$ for a certain function, is there any way of determining if there is a singularity in that point, or if ...
0
votes
0answers
347 views

Nature of the singularity in the Taub-NUT metric

Consider the Taub-NUT metric $$ds^2=-V(dt+2N(1-\cos\theta)d\phi)^2+\frac{1}{V}(dr^2)+(r^2+N^2)(d\theta^2+\sin^2\theta{}d\phi^2),$$ where $$V=\frac{(r-r_+)(r-r_-)}{(r^2+N^2)} \qquad r_{\pm}=M\pm \...
0
votes
0answers
80 views

Is it almost impossible to separate two point charges stuck together?

$$F=k\frac{qQ}{r^2},$$ if $r\rightarrow 0$ then $F\rightarrow \infty$.
0
votes
0answers
44 views

strength of each dipole charge

If I have a two dimensional dipole whose line charges are located on the y axis, I know that the electric flux through a gaussian pill box containing both the charges will be zero, that is \begin{...
0
votes
0answers
60 views

Singularity of spacetime and singularity of the riemanian tensor scalar

It's easy to show that a singularity of the riemanian tensor scalar $R_{\alpha \beta \mu \nu} R^{\alpha \beta \mu \nu}$ leads to a singularity of the spacetime. But what about the other way round? Is ...
0
votes
0answers
72 views

bose einstein phase transition

From Carter's book Thermodynamics and Statistical Mechanics, the partition function of a bose-einstein gas in $d$ dimensions is $$ \ln(Z) = -\int_{0}^{\infty}\ln(1-e^{\beta(\mu-\epsilon)})c_d\epsilon^{...
0
votes
0answers
183 views

Quantum Gravity Singularity Question?

I am not a expert in QG (Quantum Gravity) or GR (General Relativity) for that matter so please forgive if I make any small mistakes, its just a curious question but I know that a singularity is a ...
0
votes
0answers
137 views

Topology of a black hole

How many dimensions are theorized for a black hole, in view of the fact that black holes are not observed directly.
0
votes
0answers
88 views

Can we avoid singularities by embedding the manifold on a bigger space, maybe Euclidean or Riemannian?

Can singularities be avoided by embedding Riemannian manifold on bigger space, or more specifically black hole singularities can be avoided or not by embedding in any other manifold. We don't have ...
-1
votes
1answer
55 views

If all spacetime paths inside a black hole point towards the singularity, then does that mean entropy is decreasing?

Entropy is a concept of disorder. A drop of blue ink inside a glass of water only has 10^10 factorial possible ways of being an ink drop, but it has 10^11 factorial possible ways of being an ink soup. ...
-1
votes
1answer
171 views

Infinite gravity

We know that gravity works at an infinite distance. By Einstein's theory of gravity it is the result of space time curvature. So can we say that the curvature is infinitely long? How can this be even ...
-1
votes
3answers
92 views

Singularities and Infinite Range of Gravity

I'm not sure if this has been answered in the past, but if a singularity (in a black hole) Really has Infinitely strong gravity, why is it that they do not affect other celestial objects across the ...