# 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.

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### Can a gauge transformation eliminate singularity of gauge potential?

Suppose I have a gauge potential $A$ which goes to infinity at some point $x_0$. Can I use a gauge transformation \begin{equation} A'=U^{-1}AU+U^{-1}dU,~~~U=\exp\{-i\alpha^a(x)T^a\} \end{equation} to ...
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### Is there physical reason for a stably causal spacetime, or the existence of a Cauchy surface?

In their 1979 essay Global structure of spacetimes, Geroch and Horowitz describe methods of determining the topology, causal structure and singularity of spacetimes. Their (mathematical) arguments are ...
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### Are the Infinities in QFT Perturbation (closed loop diagrams) a Consequence of Point Interactions?

I have heard (and read) that the infinities that arise in QFT interactions using higher-order perturbations are "a problem that comes down to the fact that the interactions occur at a single ...
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### Is infinity measurable? [closed]

Is infinity really measurable, and can anything be measured without counting (at least to "one")? My teacher asked me whether infinity's measurable, and believes that our farthest point of ...
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### Singularity in a BH - pointlike? [duplicate]

This answer https://hsm.stackexchange.com/a/12505/13669 has the curious sentence The singularity of a black hole is not a point at its center, it's a spacelike singularity. What is that supposed to ...
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### Is there a limit to how much spacetime can be curved?

My question is about the fact that general relativity predicts bending of space and time. However, I have not seen anything regarding the limits to how much space or time can be bent. So my question ...
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### Expansion in flat spacetime

I have been studying Raychaudhuri equation and focusing theorem related to it. Focusing theorem says that if the strong energy condition is satisfied and rotation tensor vanishes $\omega_{ab}$=0 then ...
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### Is it possible that a black hole has a universe in itself? [duplicate]

Every black hole has a singularity. But the singularity is covered by a thing called 'Event horizon'or ' Schwarzchild Radius'. Our universe is originated from a naked singularity. By naked singularity,...
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### Does electric charge $e$ become complex at some scale $\mu$?

\begin{equation} \mu \frac{\partial{e}}{\partial \mu }=\frac{{e}^3}{12\pi^2}=\beta({e})\end{equation} This is the equation for beta function in quantum electrodynamics, it tells us about how coupling ...
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### What kind of causality would be broken if black hole singularities would be real?

In his article "The Universe as a Whole" 1, physicist Dennis Sciama said We therefore face a crisis in theoretical physics. Either classical general relativity breaks down, or effectively ...