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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How can two zero-dimensional black hole singularities have different masses? [duplicate]

(This question is not a duplicate because it is primarily concerned with how different zero dimensional objects/singularities with zero volume, are able to contain differing information on black holes ...
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Does a black hole singularity compress mass back into energy? [duplicate]

I was watching this PBS spacetime video which made the case that mass is just a form of bound energy. Essentially massless particles are confined in a small space giving particles the illusion of mass....
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Three types of singularities in black holes?

Now, please don't dismiss this question because of its entertaining context. Today I attended a lecture by Kip Thorne and at some point he mentioned, almost offhand, that a few years ago it was found ...
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1answer
135 views

What is wavelength at classical turning points using WKB Approximation? [closed]

According to what I know is that a classical turning point in Newtonian Mechanics is a point where a particle has a zero kinetic energy (Total energy is equal to potential energy) and must be ...
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73 views

Should stellar black holes contain a singularity? (in GR) [duplicate]

Consider a star, for simplicity a non rotating one. The corresponding spacetime will be similar to a Schwartzschild one (if the star is static and spherically symmetric). Outside the star we will ...
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2answers
161 views

Can a black hole event horizon form before the singularity for an outside observer?

This is not a duplicate, my question is not about whether BHs have or don't have a singularity, but my question is whether, because of time dilation, no matter has reached the center and formed a ...
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53 views

Due to TIME stopping, are contemporary Black Holes really just Large SHELLS of Matter and not Singularities? [duplicate]

If TIME slows down as you approach a Black Hole, has there been sufficient time in our Universe (13.8 Billion Years since the Big Bang occurred) for ANY matter inside the Event Horizon of ANY Black ...
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4answers
220 views

When GR is not valid passing the event horizon?

A test body crosses the event horizon of a black hole. When can we say that GR breaks down? Only at the singularity? At any point CLOSE enough to the singularity? How much close? In summary, do we ...
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1answer
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Finding the maximum value of electric field for a given two-dimensional charge distribution

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, ...
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2answers
531 views

Is it possible to have mass with zero volume?

As we had always studied that matter occupied space and has mass and our universe is made of matter so do that mean that there is no case where mass is present without volume .
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Point-like particle vs naked singularity? [duplicate]

In general, physics seems to consider elementary particles such as electrons to be point-like. On the other hand, naked singularities seem to cause all sorts of trouble, including closed time-like ...
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1answer
157 views

What happens when you dump antimatter onto a naked singularity?

Inspired by this question, what would happen if you dumped antimatter onto a naked singularity? The answers for the previous question suggest that once the antimatter crossed the event horizon, no ...
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2answers
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Electrostatic values where there are some charge

I've started asking myself: What is the value of the electric field at the surface of a shell with uniform distribution? In particular, is it infinite, as this point is over an (infinitesimal) ...
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1answer
159 views

Does the center of a black hole have a physical body?

From science class, I'm led to belive that all matter breaks down once it's sucked into a black hole. I get that part, but doesn't all that matter still exist in the center of the black hole? yes it's ...
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What is inside a black hole? [duplicate]

I'm trying to understand what causes a black hole in terms of it's composition. We know a start can die and collapse into a neutron star, but if the neutro star is not dense enough to create a black ...
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1answer
113 views

Black hole and its density

I'm an amateur to astrophysics but I'm slowly teaching myself things and I have these three doubts. How does more compression relate to a stronger gravitational pull. Like, when we say that a black ...
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1answer
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Black holes as universal "anchors"? [closed]

I'm not a Physicist, but was watching a program about black holes. As I understand it time and space "stop" at the singularity of a black hole, which made me think of a black hole as some kind of "...
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Is math truly infinite or is it just theory? [closed]

I imagine you can theoretically add +1 to any number But untill it happens it isnt so. That + no free will = math is limited and has a definite value. I imagine its tied in with conservation laws... ...
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1answer
156 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 ...
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1answer
362 views

Metric diameter of a ring singularity

In the Kerr metric the ring singularity is located at the coordinate radius $r=0$, which corresponds to a ring with the cartesian radius $R=a$. So the center of the ring singularity in cartesian ...
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3answers
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Can the electrostatic force be infinite in magnitude? [closed]

The magnitude of the electrostatic force between two charges $Q$ and $q$ separated by a distance $r$ is given by $$F=\frac{kqQ}{r^2}$$ but the minimum value of $r$ must be $10^{-15}\ \rm m$. Therefore,...
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2answers
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Curl and circulation of a vector field that is ill-defined at the origin: any interesting physical effects?

In the cylindrical polar $(\rho,\phi,z)$ coordinate, suppose the velocity field in a liquid is given by $$\vec{v}=\frac{K}{\rho}\hat{e}_{\phi}, \qquad K=\text{constant}.\tag{1}$$ It can be easily ...
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3answers
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Does time stop inside a black hole? How about at its singularity?

I'm a layperson who just read Brief Answers to Big Question and in the book, Hawking proposes that: A typical black hole is a star so massive that it has collapsed in on itself. It’s so massive ...
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1answer
79 views

UV divergence integral

Could anyone please explain how to calculate integral such as $$\frac{\Omega}{2}\int_{-\infty}^{+\infty} \frac{d^3k}{(2\pi)^3}\ln\left[{1+\frac{a^2}{k^2}}\right]=-\frac{\Omega a^3}{12\pi}+I_0~?$$ ...
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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 ...
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4answers
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Solutions to Newton's laws with unbounded kinetic energy for inverted harmonic oscillator potential

In a one dimensional setting, Hooke's Law, together with Newton's 2nd law, results in a differential equation of the form (setting the constants $m$ and $k$ equal to 1 for notational simplicity) $x''(...
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86 views

Black hole fundamental laws [closed]

As the Laws of physics breakdown during inside a black hole, would we have to create new fundamental Laws?
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250 views

If a black hole cannot have a diameter smaller than Planck length (a finite and non-zero length), then how can we call it a singularity?

As title. If a black hole has a minimum finite diameter, than it should not mathematically be a singularity.
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81 views

Does a Black-hole Represent a Limit To The Value of Energy-density? [closed]

I've recently read an article that stated the singularity of a black hole could be a string, which is stipulated to be pure energy. If that's the case, does this mean that the singularity of a black ...
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3answers
831 views

If a Black Hole Singularity is a 1 Dimensional Object, How Does it Affect 4 Dimensional Space

If the center of a black hole is an one-dimensional point, gravitational singularity, where density and gravity become infinite and space-time curves infinitely, then / why: If spacetime is warped ...
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1answer
848 views

Could the singularity of a black hole just be an iron / dark matter sphere? [duplicate]

A singularity would break physics wouldn't it? How does a massive star collapse and suddenly fall into a point in space with no dimensions what so ever when it had a core and perfect balance between ...
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1answer
45 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 ...
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3answers
322 views

Physical Interpretation of $\nabla \cdot \vec{E} = \frac{\rho}{\epsilon_0} $

The differential's form of Gauss' Law is $$\nabla \cdot \vec{E} = \frac{\rho}{\epsilon_0}. $$ This suggests that at every point in space, the the electric field $\vec{E}$ is determined by the charge ...
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2answers
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Was the singularity just a mini model of our current unvierse? [duplicate]

Did the singularity just "containe" the matter, the energy and the space-time or it created them. If it just contianed them and then the expansion hppened, can we say it was just a mini model of our ...
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2answers
156 views

Where is the Physical Singularity under the Holographic Principle?

From this article, it states that The holographic principle states that the entropy of ordinary mass (not just black holes) is also proportional to surface area and not volume; that volume itself ...
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6answers
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Why exactly are singularities avoided or "deleted" in physics?

What is the real reason that make us reject singularities everytime we see them in a theory/model? For example, in GR, it is predicted that black holes singularities have infinite density. This makes ...
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1answer
109 views

Naked singularities and mass distribution of a black hole

Do naked singularities also appear mathematically if the mass of a black hole is uniformly spread around its Schwarzschild surface? I recently heard about the concept of a naked singularity and it ...
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2answers
598 views

Is the zero distance limit of Coulomb's law something to worry about?

Coulomb's law fails when the distance $r$ between to point charges vanishes. As $r\to 0$, the electric field between two point changes increases without limit. I should be bothered about the limit $r\...
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Would a cellular-automata universe allow singularities to exist?

It is usually assumed (almost always) that cosmological singularities (like black hole singularities) are impossible and do not exist in the universe. If the universe was like a cellular automata (...
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3answers
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BH singularity? Infinite density

How can the density of a region of space go from finite density to infinite when there are no numbers larger than any Aleph0 number but smaller than any Aleph1 number (no decimal point in front of it, ...
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3answers
520 views

How to find electric field at a point on an arbitrary surface charge $(\sigma)$ due to it?

Electric field at any point due to any volume charge $(\rho)$ Electric field at a point outside a volume charge is given by Coulomb's law: $$\vec{E}=k \iiint_V \dfrac{\rho}{r^2} (\hat{r})dV \tag1$$ ...
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1answer
325 views

Is the Big Bang a naked spacelike singularity?

While reading some answers on similar topics, I was wondering about the nature of the Big Bang singularity in the standard cosmological model. I know it's a spacelike singularity that have a ...
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1answer
106 views

Silly question about Schwarzschild Black holes and scientific communication

Well, in scientific communication literature often we encounter the following phrase about black holes: A Black Hole is a body that have infinite curvature and infinite density So, with basic GR ...
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460 views

Naked singularity

Many consider naked singularities as a fundamental problem and that it should be always covered by a horizon (Cosmic censorship hypothesis). But why naked singularities are really a problem? If we ...
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1answer
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Can the gravitational field be considered conservative despite the existence of singularities?

Assuming singularities are physical objects as opposed to mathematical artifiacts, can the gravitational field still be considered conservative? And if not, does this open a possibility of breaking ...
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1answer
93 views

Functions unbounded at a point on the domain: How to show electric field exists for any continuous volume charge density?

My understanding after reading Mike Stone's answer: \begin{align} \vec{E} &= k \iiint_{V} \dfrac{\rho(x',y',z')[x-x'\hat{(i)}+y-y'\hat{(j)}+z-z'\hat{(k)}]}{[(x-x')^{2}+(y-y')^{2}+(z-z')^{2}]^{...
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3answers
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Does time exist at the center of a Black Hole?

A black hole is a wormhole resulting from a dead Star which is capable of sucking any mass/matter along its path due to Gravity. I was wondering what time would be like at the central point of the ...
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1answer
106 views

Magnetic field at points on the circuit

I know magnetic field lines due to a circuit always form closed loops. Therefore $\nabla \cdot \vec{B}=0$ everywhere (even at points on the circuit). However due to singularity, magnetic fields are ...
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2answers
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Weyl anomaly in 2d CFT (string theory lectures by D.Tong)

In his lectures on String Theory (http://www.damtp.cam.ac.uk/user/tong/string.html), Tong gives a proof of the Weyl anomaly, using equation $(4.36)$. It seems wrong to me. Here he uses the OPE between ...
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1answer
165 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 ...

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