# 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 [black-holes] and [wormholes] for certain kinds of singularities occurring in general relativity. For the procedure of "getting rid" of singularities, consider the [regularization] tag.

891 questions
Filter by
Sorted by
Tagged with
4k views

### Do black holes have a size?

I'm wondering if one can say that a black hole is an object "made of matter" that has a size (as a size, I'm not talking about the size of the event horizon). I would like to know if one can ...
• 187
78 views

### Understanding the Singularity of Black Holes [duplicate]

Could someone please explain how we know the singularity has an infinite density and zero size/volume? From reading around online black holes have a defined radius (the event horizon) but this isn't ...
• 555
76 views

### Where does the singularity go in an Einstein-Rosen Bridge?

I've been reading up on some material about black holes and Einstein-Rosen bridges. Generally it is said that a black hole is defined by the event horizon (boundary in space where the gravitational ...
1 vote
44 views

### Order by order renormalization

This post is a little bit related with my last post, where I don't totally understand one point. I think it's better to write a new post specialized for this point. For a renormalized $\phi^4$ theory, ...
• 1,133
223 views

### Peskin & Schroeder Introduction to Quantum Field Theory, two-loop renormalization example

In Peskin & Schroeder's An Introduction to Quantum Field Theory, section 10.5, page 338, the book gives a two-loop renormalization example (in scalar $\phi^4$ theory). Before we start the two-...
• 1,133
1 vote
37 views

### Dirac string and nature of singularities

The Dirac magnetic monopole is defined as \begin{align} \vec{B}=\frac{g\vec{r}}{r^3}\,, \end{align} where $g$ is the strength of the monopole and $\vec{r}$ a vector. It is possible to show that the ...
124 views

• 657
1 vote
98 views

### Computing $\langle 0|S |0\rangle$ in $\phi^4$ theory [closed]

$\newcommand{\bra}{\langle #1|}$ $\newcommand{\ket}{|#1\rangle}$ I have been reading David Tong's QFT notes. As part of an exercise, I am asked to examine $\bra{0} S \ket{0}$ to order $\lambda^2$...
• 111
66 views

### When falling freely into a black hole, how far does space extend out in front of you? [closed]

Falling freely into a black hole (assuming we survive or being point-sized) all particles in front of you are accelerating away from you in the direction of the singularity which seems flying towards ...
37 views

### How to verify the corectness of a renormalization scheme?

I am currently studying renormalization and have the above question about the renormalization scheme. So as far as I understand when we renormalize, we come from the realization that there are ...
• 533
63 views

### How do infinitely dense singularities evaporate trough hawking radiation?

If we assumed that a black hole with a singularity of infinite density eventually evaporates due to Hawking Radiation, does this affect the singularity itself? If mass is preserved in the singularity ...
1 vote
75 views

### Mass in the LSZ reduction formula

I'm reading wikipedia's page on the LSZ reduction formula https://en.wikipedia.org/wiki/LSZ_reduction_formula For the scalar LSZ reduction formula, after performaing a Fourier transform on the $n$-...
• 570
1 vote
130 views

### Is singularity without black hole possible?

I read things related to the topic I am asking and I found the idea of a "Naked Singularity" but naked singularities can't be created without black hole. I need to know whether it is ...
1 vote
161 views