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 ...

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Is a black hole's mass uniformly distributed?

If you were to fly around a black hole, would the gravitational pull be uniform and centered on the singularity, regardless of your relative location? If yes, how can this be consistent with models ...
22
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4answers
3k views

Why do physicists trust black hole physics?

Based on popular accounts of modern physics and black holes (articles, video lectures), I have come to understand the following: Black holes are predicted by General Relativity, a classical theory ...
0
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2answers
53 views

Do the stellar remnant in a black hole have spatial extent? [duplicate]

I am not talking about event horizons. I am talking about the actual remnant of stellar collapse. Is it just a point, hence the problem with the singularity? Or does it have a finite volume that we ...
0
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0answers
22 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) = ...
3
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3answers
916 views

How many dimensions does a singularity have?

my understanding of a singularity is that it is a 'point' in the universe with an infinite energy density. I have also read on the internet that a singularity is one-dimensional. This is a concept ...
2
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1answer
69 views

Naked singularity: how would it behave?

We know that the theory of cosmic censorship prevent singularities from existing without an event horizon that hides them from the Universe. Now let's assume that this theory is somehow false, and a ...
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4answers
737 views

What exactly is meant by infinity?

What exactly is meant by infinity when I see it in a physics equation (always something wrong?)? And in experiment how many orders of magnitude can be treated as infinity (say, if infinity is ...
1
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1answer
98 views

Is the vortex in a kitchen sink an example of a singularity?

Say you have your kitchen sink full of water and you pull the plug. Then a nice little vortex will form where the water disappears into the drain. My question is: Is this an example of a ...
6
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2answers
105 views

Does geodesic incompleteness in Penrose-Hawking theorems imply curvature blow up?

The singularity theorems in General Realtivity roughly stated say that given: A global causal condition An energy condition The existence of a closed trapped surface then spacetime must be ...
0
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0answers
33 views

How can a singularity have infinite density? [duplicate]

I've heard many times that black holes have infinite density at their center, but I've also heard astronomers quote mass estimates for black holes. How could the singularity have infinite density if ...
4
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4answers
367 views

“Center of a black hole is a time”

$\newcommand{\d}[1]{\mathrm{d} #1}$In one lecture (around 1:33:15) of the series of lectures "Theoretical Minimum" of Prof. Susskind he talks about black holes and the Schwarzschild metric: $$\d ...
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2answers
134 views

The Big Bang theory hypothesis

Is there a simple way to state the hypotheses of the Big Bang theory? I have the impression that the Big Bang singularity is merely a consequence of Freedman equations. Could somebody clarify what ...
0
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1answer
54 views

Do all paths leading into a black hole lead directly at the exact center of the singularity? Or could they go very near it and curve back?

I only have a very basic understanding of general relativity, so this might sound stupid. But as I see that gravitational objects orbiting each other, even if one of them is massive, as long as their ...
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2answers
1k views

Is Gravity a Problem?

I was watching the movie "Interstellar" recently and in that a character "Romly" mentions that if he could peep into the black hole "Gargantua" he could solve gravity. I have a questions, is that a ...
1
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1answer
94 views

What is the physical origin of van Hove singularity?

I am trying to build physical intuition about van Hove singularities. The density of states for a system with energy dispersion $E_\vec{k}$ is defined as $$ D(E) = \int_{S(E)} \frac{dS}{4\pi^3} ...
2
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1answer
190 views

Obtaining a copy of Hawking's Ph.D thesis - Properties of Expanding Universes

Due to its popularity, I am interested to know the 4 chapter titles and topics covered in S.W. Hawking Ph.D, Properties of Expanding Universes. I also ask this because that thesis is hardly available. ...
0
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2answers
60 views

if singularities can be observed from the rest of spacetime, causality may break down

if singularities can be observed from the rest of space-time, causality may break down, and physics may lose its predictive power,i don't understand how it will happen?we don't have any idea what will ...
0
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1answer
46 views

Influence of spacetime curvature on electromagnetic wave propagation [duplicate]

Classical physics assumes that spacetime is evenly distributed in the sense that Coulomb's Law predicts that a charged particle will create a spherically symmetric electric field around its location. ...
5
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2answers
106 views

Elementary question about endpoint singularities

In George Sterman's book "An Introduction to Quantum Field Theory", on pages 413-414, there is a description of the endpoint singularity. One begins with the function $$ I(w) ~=~ ...
4
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2answers
362 views

Age of the universe and the singularity at the Big Bang

Using the standard model of cosmology we calculate the Hubble time to obtain an estimate of the age of the universe. This model assumes a beginning of time in the past. But that point is a true ...
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1answer
52 views

Singularities in the Reissner–Nordström metric

I am doing a presentation on black holes but I'm having trouble finding information on the Reissner–Nordström metric. From the metric ...
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0answers
39 views

Colliding black holes to an outside observer

We know that a particle approaching an event horizon will appear to an outside observer to slow down and never cross the horizon. What is observed by an outside observer when a singularity ...
1
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3answers
62 views

Why is the zero of electric potential taken to be $r = \infty$, rather than $r = 0?$

Wouldn't it make more sense if it was taken to be zero at $r = 0$? This seems to imply that with a negative test charge at $r = 0$ from a positive point charge, $V = -\infty$, which I have trouble ...
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1answer
59 views

Is the concept of infinity valid in physics, beyond its convenience? [duplicate]

Is infinity a meaningful concept in physics, apart from making some of the maths easier? Especially since reality seems to be discrete.
0
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1answer
72 views

Why do inverse square forces not rise asymptotically for $r\to 0$?

An example of an inverse square force is the gravitational force: $$ F = \dfrac{G m_1 m_2}{r^2}$$ For large bodies I can understand why the force does not rise asymptotically as you get closer. For ...
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3answers
162 views

Is a black hole a 3D hole? And doesn't it pull into the 4th dimension?

Hear me out here please: A body on a line (a 1-D world) causes a warp in the line, i.e. a curve (2-D) A body on a plane (a 2-D world) "sinks", causing a warp in the plane, i.e. a pit (3-D) Then does ...
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0answers
30 views

Infinite force between two point charges as $r$ approaches 0 [duplicate]

According to coulombs law the Force experienced by two point charges increases with the inverse square of their separation. This would imply that at distances approaching 0, the Force approaches ...
0
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0answers
14 views

Rotating conical singularities in three dimensional gravity

A conical singularity in three dimensional flat space is usually desrcibed by the metric $ds^2=-dt^2+dr^2+r^2\gamma^2d\phi^2$ In three dimensional gravity with a negative cosmological constant, we ...
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3answers
2k views

Black hole with two singularities?

I hope this question isn't too naive, but would it theoretically be possible to have a black hole with 2 singularities (or 2 black holes at the same location). If this is possible, would there be any ...
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4answers
2k views

Why is the singularity of the Big Bang not considered to be the center of the Universe? [duplicate]

If the universe is expanding, then at some time in the past, it must have started from a single point but why this point is not the center of the Universe. Just like the singularity of black holes is ...
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0answers
38 views

Force of gravity at quantum level is indetermined?

Newton's law of Universal Gravitation states that any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional ...
0
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1answer
129 views

How does a wormhole form? [duplicate]

I heard about wormholes. I know that they are paths that can be got by contracting spacetime. But, how does a wormhole form?
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0answers
58 views

Black Hole singularity in Loop Quantum Gravity

How is the singularity of a Black Hole treated in Loop Quantum gravity ? Does it go away ? And if it does, what's after the event horizon ?
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0answers
96 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 ...
6
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5answers
479 views

How to understand singularities in physics?

The question is probably two-folded and I will try not to make it too vague, but nonetheless the question remains general. First fold: In most physical laws, that we have analytic mathematical ...
1
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1answer
68 views

Location of singularity in moving black hole

Say a black hole is travelling at $c/2$, does the shape of the event horizon change? What about the location of the event horizon? If it is travelling at a hypothetical $c$, does the event horizon ...
0
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1answer
40 views

Why is a freefall trajectory the slowest path to the singularity of a black hole?

Back in June 2007, a Belgian newspaper reported on an article from Nature from 2 Sydney University astrophysicists named Geraint Lewis and Juliana Kwan, who claimed that once you passed the event ...
1
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1answer
29 views

Black holes in a denser media

In Crown Glass, the speed of light is 1.52 times the speed of light in vacuum. Consider the following hypothetical situation: Hypothetical Situation If a black hole is surrounded by a giant crown ...
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0answers
18 views

Olbers' paradox and singularity resolution

As Im sure many fo you there are many attempts at singularity resolution in quantum gravity approaches such in LQC and string theory. In the last few week there was a lot of press for a new approach ...
2
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3answers
214 views

Is the difference between an event horizon and a singularity merely perspective?

I know the question has been asked about how an event horizon is distinguishable from a singularity given that time must come to a stop at the event horizon, but I haven't been fully satisfied by the ...
6
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3answers
177 views

When are infinities okay?

I'm a little confused about how to handle infinities in physics. On the one hand, I always here things like infinities are not physically tenable answers. GR can't answer anything about the origin of ...
7
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5answers
2k views

Why aren't all black holes the same “size”?

The center of a black hole is a singularity. By definition, a singularity has infinite density. So how can a black hole with a different mass or density be described?
0
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0answers
38 views

Infinite universe, big bang = no singularity? [duplicate]

If we traced an infinite universe back in time towards t=0(ish) would a singularity still be formed? Would the singularity be infinite in size? (To me it seems it would have to be) This reminds me ...
1
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2answers
178 views

Can a sufficiently large black hole be singularity-free?

This came to me after reading that a black-hole that has the mass of the observable universe will also have an event horizon that covers the observable universe. Since the definition of a black hole ...
1
vote
1answer
46 views

What exactly are the ADE type of gauge theories?

What exactly are the ADE type of (susy) gauge theories? What exactly we mean, intuitively, the ADE singularities? What are their relation to brane constructions and do you have any references one ...
0
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0answers
70 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.
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0answers
34 views

Did spacetime curve infinitely about 13.7 billion years ago? [duplicate]

GR/Big Bang Model implies that there was a singularity about 13 billion years ago, in which all the matter and energy along with the observable universe (or perhaps, the entire universe) was ...
1
vote
1answer
577 views

Why does the Ricci tensor vanishes in Schwarzschild metric? [duplicate]

If the Schwarzschild metric is suppose to describe the behaviour of a spherical object in flat space, so the Schwarzschild is different from the flat metric because it describes curved space so why ...
0
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2answers
134 views

How could the “Big Bang” singularity have actually expanded? [duplicate]

We have mountains of evidence about singularities and how they work, and we have mountains of evidence that the "Big Bang" was the origin of the universe as we know it. But if compressing enough ...
92
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3answers
15k views

How come some people are claiming that the Big Bang never happened?

A news story is going viral on social media networks claiming that two physicists have found a way to eliminate the Big Bang singularity, or in layman's terms (as claimed by many sensationalist news ...