All Questions
Tagged with black-holes singularities
462
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Necessity of Singularity in General Relativity
The Schwarzschild solution is the standard example used to describe a black hole, its important points being the event horizon and the central singularity. But this solution is derived by assuming an ...
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Can you calculate the radius of a hypothetical singular surface inside a black hole from observing changes to its linear momentum?
Say there is a ball of unknown radius surrounded by a bubble. The ball represents a hypothetical singular surface inside a black hole and the bubble represents the event horizon.
If you threw marbles ...
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3
answers
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Is the size of a black hole singularity smaller than a fundamental particle?
I am wondering about the size of a black hole singularity. We know that a classical black hole is infinitely dense. I am not asking about size of event horizon. I am asking about actual size of the ...
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Where is the mass in a Black Hole without a "central" curvature singularity?
Not all black holes have a curvature singularity at their center (an example). But in principle, I thought that the curvature singularity was a direct result of the fact that the mass is concentrated ...
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Realistic black holes
If I understand the answers provided in this Link Why singularity in a black hole, and not just "very dense"?
Then the singularity at $r=0$ may just be a mathematical artifact, and may not ...
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Can a Kerr black hole become super-extremal?
Let's assume there is a large Kerr black hole, which is almost
extremal and would become extremal with the addition of a small
amount of mass $M$ with spin $J$ to make the final $J=M$.
What if this ...
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How do black holes move if they are just regions in spacetime?
If black holes are just regions of spacetime, how can black holes even move? When matter moves through spacetime, it bends the spacetime around it, but if black holes are just regions of spacetime, ...
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What happens to the ring singularities when two Kerr black holes merge?
Imagine two Kerr black holes with ring singularities oriented in different axes (e.g. one horizontal and the other one vertical). If they merge, what will happen to these singularities? Will they form ...
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What are spinning black holes orbiting?
I have seen depictions of spinning black holes with the "singularity" spinning around a center of rotation in a flat plane, or moving around an imaginary sphere. Is there anything in the ...
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Singularity of a black hole: point or solid sphere? [duplicate]
A black hole is defined by its event horizon. The event horizon has a Schwarzschild radius of,
$$r_s=\dfrac{2GM}{c^2}$$
Technically, this means that any body of mass, $M$, with a radius smaller than ...
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Regularization of black hole singularities
Hi I have a question: when dealing with the gravitational Lorentz factor from schwarzchild solution to EFE, used in defining gravitaional time dilation and one encounters singularities at $r=0$ or $r=...
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Is the Schwarzschild singularity a limit of the Kerr singularity?
In a Schwarzschild black hole, the singularity is spacelike. In a Kerr black hole, it is timelike.
Is there any continuous transformation between those solutions? Can the Schwarzschild solution be ...
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2
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Why domain of Kerr black hole includes negative values for $r$ coordinate?
I understand the domain of $t$ is all real numbers but mathematically, how to prove the domain of $r$ coordinate is also all real numbers except $r=0$ when $\theta = \pi/2$. I know that we get two ...
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Black holes, singularities and topology in relativity
General relativity is defined on a base manifold which, viewed as a topological space, is simply connected (which means there's no holes). However, we know that inside a black hole there's a ...
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Can super heavy elements form inside black holes?
I have read that heavy elements like gold and uranium are formed due to extreme pressure, through a process similar to nuclear fission. I wonder if something like atomic no. 500 or 5000 could form ...
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Types of singularities
I am confused about the types of singularities. According to my limited knowledge there are two types of singularity. One is space like singularity ( a curvature singularity enclosed within a null ...
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How to find that there is a conical singularity in the BTZ black hole?
Considering a non-rotating and non-charged 2+1 dimensional black hole, known as the BTZ black hole which obtained by adding a negative cosmological constant $\Lambda=-\frac{1}{l^2},l\ne0$ to the ...
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Don't Geodesics change due to other geodesics?
So the geodesics that point towards the Earth brings space-time towards the Earth and then back out again, but then the moon has its own geodesics so wouldn't it be kind of like geodesics affecting ...
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Range that the Schwarzschild metric is valid
The Schwarzschild metric is the metric calculated from the field equation outside of the black hole. This condition of region (outside of the matter) was the reason why we could use $T_{\mu\nu}=0$.
...
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What physical quantity is a black hole singularity refering to and why is it special?
What mathematical term actually shows a "singularity" in a black hole and why is this so special compared to other singularities? It seems super hard to find any concrete formulas about the ...
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What happens if $ a^2 > M^2 $ in Kerr metric?
(Boyer-Lindquist coordinates and $ c = G =1 $ taken)
As I know, line element in Kerr metric $ d s^2 = - \left( 1 - \frac{2Mr}{\rho^2} \right) d t^2 - \frac{4 M a r \sin^2 \theta}{\rho^2} d \phi d t + \...
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How do black holes infinitely bend space-time when the bending is mass dependent and not density dependent?
According to Einstein, mass bends the fabric of space-time. And nothing in the universe has infinite mass to infinitely bend space-time. So how do remnants of supermassive stars, i.e black holes ...
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Black hole singularity [duplicate]
Suppose a cloud of dust of sufficient mass and density collapses to form a black hole. As this mass falls within the event horizon, to an outside observer it enters an area of infinite time dilation. (...
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Question about Kerr's recent paper regarding Penrose et al.'s works on gravitational singularities [duplicate]
R. Kerr posted an essay on arxiv recently.
Kerr claims:
The consensus view for sixty years has been that all black holes have singularities. There is no direct proof of this, only the papers by ...
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Will this hypothetical circular singularity FTL travel warp drive work? [closed]
Not a physicist, but just wanted to know if this would work in theory:
Since nothing can practically travel faster than the speed of light (for now until proven otherwise), the only way for ...
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Can the gravitational singularities of black holes be solved by potential or self-energy?
In Newtonian Mechanics, the energy density of gravitational field is negative in comparison with the positive energy density assigned to mass density, meaning that that the total positive energy of ...
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Why does Roy Kerr claim that the Kerr black hole does not contain a singularity?
In a preprint posted on the arXiv, Roy Kerr claims that there is a widespread misunderstanding related to the singularity inside the black hole that bears his name.
Can anyone explain his argument in ...
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Eigenvalues of the geodesic deviation equation, curvature invariants, and singularities
The geodesic deviation equation tells us what tidal forces freely falling observers experience in a local Lorentz reference frame. The tidal deformation tensor is
$$E^{\alpha}_{\gamma}=R^{\alpha}_{\...
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Why do we defer to GR when describing black holes rather than rely on QM?
This is a broad question but it's well documented that GR and QM are very well tested in their own domains but they conflict around black holes.
Picture a neutron star slowly accreting matter until it'...
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If it's a common myth that a black hole contains a singularity, what does a black hole actually (likely) contain?
It's a common myth (especially in popsci) that a black hole contains a singularity. However, I cannot find an explanation for what we think a black hole actually does contain. The best I've seen is &...
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Equivalence principle near a black hole
At every spacetime point, there is a locally inertial frame in which the effect of gravitation is absent. Can this point be taken near the center of a black hole?
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Why can't the answers to equations be infinity?
When talking about black holes and singularities, most books say that combining relativity and quantum mechanics gives the answer of infinity in some equations. They also say that:
Infinity is the ...
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What does it mean for the laws of physics to "break down" at a singularity? [duplicate]
When the statement says:
As you get to the center of a singularity the laws of physics "break down".
What exactly does that mean?
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How can the distance to the event horizon, as measured by a tape attached to a falling mass, be reconciled with the mass passing through it?
When hovering 2km. above the horizon of a black hole with a mass of the sun, at r=5km., the distance you measure with a measuring tape attached to a mass you throw in the hole will tell you the ...
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How far does a particle fall before it hits the singularity of a black hole?
Even though a black hole has a Scwarzschild radius that indicates a finite small distance to the center of the hole, the distance traveled by an infalling particle seems a lot bigger than the ...
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Can the inertia factor of a black hole be used to infer its density profile?
The Sun's inertia factor of ~0.07 suggests a stark contrast between the density of its outer shells (very low density) and its core (very dense). The same applies to the rest of the solar system. ...
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Hypothetically, could the interior of a black hole look exactly like the universe that surrounds us?
I do understand that we can't experimentally verify anything we imagine about the interior of a black hole.
If we were to apply what we know about the physics of the observable universe and assume ...
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How can we be sure that black hole's singularity is not a missunderstanding? [duplicate]
The Newtonian gravitational potential is given by:
$$\phi=-\dfrac{GM}{r}$$
Which appears in the Schwarzschild metric tensor with a so-called singularity at $r=0$. Nonetheless, I can't get why is it ...
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Could a high energy content prevent a singularity inside a black hole?
Very roughly, dark energy tends to cause space to expand and mass tends to cause space to contract. If nothing gets in the way, the math on that contraction breaks down when it forms a black hole ...
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How can there be a naked singularity in the Reissner-Nordström (RN) geometry? [duplicate]
I recently read that, if the mass of a charged black hole is small (compared to its squared charge times some constant), than there is no event horizon, but there is still a (naked) singularity. My ...
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Is there any remote possibility that a singularity may be real? [closed]
Usually, when physicists talk about singularities in Einstein's theory of relativity, they say that these cannot exist and that they are only mathematical artifacts that indicate that is likey that ...
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Schwarzschild metric with negative mass
Can mass be negative in Schwarzschild metric? If we use $M<0$, will it still be a solution to EFE? If not, why?
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Is $\theta=0$ a coordinate singularity in the Schwarzschild metric?
We often hear this example of coordinate singularity. We can describe the 3D Euclidean space using rectangular or spherical coordinates. But in the spherical coordinate, the north pole $(r,\theta=0, \...
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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 ...
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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 ...
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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 ...
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Is it possible for a black hole singularity to interact gravitationally with other celestial bodies (if we analyze it using the concept of gravitons)? [duplicate]
It is known to all that the travelling speed of gravitons (the propagation speed of gravitational field) is not instant. So for black holes, the gravitons (the gravitational field) generated by the ...
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Is there any evidence black holes can grow (gain mass) by accretion?
When LIGO detected GW150914, we saw for the first time the merger of 2 black holes and the gravitational wave evidence fit with our models and understanding for such an event. (Horizon meeting horizon)...
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Star collapses to a singularity or is collapsing into singularity?
This has bothered me for a while now, however I barely have a vocabulary to ask it. Please let me try.
When a star, at the end of its life starts to collapse into the black hole, all the atomic forces ...
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