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Questions tagged [white-holes]

In general relativity, a white hole is a hypothetical region of spacetime which cannot be entered from the outside, although matter and light can escape from it.

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Can a white hole turns into a black hole?

I have been trying to read Penrose diagram to understand what white hole can do, but can the white hole collapses into a black hole and if so then what kind of conditions would turn a white hole into ...
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Does a white hole forms accretion disk?

A white is time reversal of a blackhole at least mathematically, I know it can't exist but may I know if it can form accretion disc similar to those stellar mass black holes. Does it spins on it's ...
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Is an Einstein-Rosen Bridge theoretically required to have matching Schwarzchild radii on either end?

Is there a solution where the mouths on either end can have a different radius? I am also curious about these types of requirements in the case of a multi-mouth wormhole. Thanks for your time.
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How are white holes described as outgoing spacetime and still have attractive gravity?

White holes are described by the time reversed Schwarzschild metric. A test particle which is gravitationally attracted to the black hole's event horizon in the Schwarzschild metric is also ...
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Distinction between behavior of spacetime inside a black hole during evaporation and the phase of transition to a white hoöe, in Loop Quantum Gravity

I was just watching: Carlo Rovelli (2023). What is a white hole? The Royal Institution (YouTube). Rovelli mentions at 36 minutes that the transition to a white hole state is more likely than ...
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White Holes Evidences

It is well known that in the canonical quantization program for quantum gravity, like LQG/Wheeler-De Witt/Polymer QM, almost every prescription when applied to cosmology/gravitational collapse leads ...
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What would happen if you threw an object (a tennis ball for example) at a white hole? [duplicate]

I know white holes are hypothetical but IF they were real, what would happen if you threw an object at the white hole ? will the object get repelled as soon as it gets close to the white hole or will ...
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Seeking Visualization Tools for Hypothetical Black Hole Concept

I have a idea I'd like to explore: If a black hole can bend light due to its immense gravitational attraction, could we imagine an 'inverted black hole'? In this hypothetical scenario, this object ...
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Why are there two interior regions in this diagram?

Why are there two interior regions in this diagram? There seems to be two inner horizons, and two wormhole regions. Where do the two such regions comes from? What determines which reason someone falls ...
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Where do the other black holes in this diagram come from?

In this Penrose diagram for a charged/Rotating black hole, once your in the new universe you can continue onward to an infinite sequence of black holes/white holes. So I'm asking, where do those black ...
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Does Noether's theorem apply to bouncing black holes? [closed]

Noether's theorem states that every differentiable symmetry of the action of a physical system with conservative forces has a corresponding conservation law. Energy, however, is not conserved in an ...
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Kruskal Coodinates and Diagram: Past and Future Horizons for White and Black holes?

I was reading Prof.Tong's notes where everything went smooth until when he just stated that for Kruskal coordinates $$U=-\exp(-u/4GM), V=\exp(v/4GM),$$ the horizon $r=2GM$ of Schwarzschild metric ...
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How to describe region around a white hole using a metric tensor?

A white hole is a hypothetical region in spacetime predicted by general relativity. Although none is discovered, it exists on paper. With a metric tensor, it should be possible to simulate the ...
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Energy conservation in Black Hole White Hole system

Does energy remain conserved in each of the 'universes' of a maximally extended black hole-white hole system (Kruskal coordinate system)? Referencing from Wikipedia: "This means that the interior ...
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Penrose diagram of hypothetical astrophysical white hole

Assuming classical physics (no Hawking radiation), spherical symmetry, and no charge, Penrose diagrams are well known for the maximally extended Schwarzschild solution, for the theoretical (not ...
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Black hole and white hole question [closed]

If white holes are the other ends of black holes, what if a black hole absorbs the white hole it is connected to, and then if it is absorbed by another blackhole bigger than the first, but the white ...
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Are white holes hotter than our Sun?

A white hole is a theoretical region of spacetime and singularity that cannot be entered from the outside, although energy-matter, light and information can escape from it. In this sense, it is the ...
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For an object that has fallen into a black hole, does the event horizon they went thru look like a white hole?

This question is not asking if the event horizon is white hole and a black hole, as the answers to the linked question explain why. The question I am asking here is more like the following. If a ...
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Can Black hole eat white hole or white hole eat black hole? [duplicate]

No light can enter black holes, but is it possible for a white hole to enter a black hole? Or vice versa? Could there be black holes inside the white holes? Or were there black holes inside them that ...
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${}$Hawking radiation and Einstein-Cartan theory

As I understand it, Einstein-Cartan theory predicts that inside every black hole, there is an einstein rosenbridge connecting to a new universe that forms due to a white hole. Where does hawking ...
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Is it experimentally verifiable if we are a inside a white hole that never fully formed?

There are a lot of questions on this site about white holes, but none of them specifically answer my question. Most of these questions talk about observing white holes from outside, but do not talk ...
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If white holes are just time-reversed black holes, then can they split just not merge?

I have read this question: Equations of fundamental physics are usually time-reversible (particle physics is time-reversible in a CP or CPT sense, though) which means you can take a certain reversal ...
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Would a black hole-white hole pair self-propagate?

Would a black hole-white hole pair of equal size self propagate in the direction of the black hole? Suppose the pair are initially stationary relative to each other, with the white hole on the x axis ...
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Do white holes bend light?

White holes share a great deal of properties with black holes such as being completely characterized by rotation, mass and charge, even they have a Hawking temperature. However, I am not able to argue ...
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How do we know that quasars are not white holes?

White holes are speculative in nature. Black holes are known to exist (supermassive black holes in galactic nuclei and stellar-mass black holes in binaries). My question: if white holes are expected ...
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Black hole and white hole symmetry

NB: This question comes from an idea I had while watching this video about the video game portal and its sequel (link: https://www.youtube.com/watch?v=aj8NDOA0Sgw at 15:30 the idea of a black hole was ...
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White hole region in Kruskal–Szekeres coordinates and geodesic

We use Kruskal–Szekeres coordinates$(T,X)$ to describe black hole and white hole. For $r>2GM:$ $$T = \left(\frac{r}{2GM}-1\right)^{1/2}e^{r/4GM}\sinh\left(\frac{t}{4GM}\right)\\$$ $$X = \left(\frac{...
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Would light emitted from a white hole be red-shifted or blue-shifted?

if it's not that straight-forward, what factors would effect the resulting appearance of light emerging from a white hole?
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Is it possible we live in a white hole?

Is it possible we live in a white hole? We live in a universe that is expanding at an accelerating rate – does this not seem similar to a white hole? Could a living organism interpret a black hole as ...
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To an observer inside a black hole, why is the rest of the universe outside the black hole not a white hole?

To an observer inside a black hole, why is the rest of the universe outside the black hole event horizon not a white hole? It is a region the observer could never enter. It is a region from which ...
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Are black holes exploding just like the singularity at the big bang did, we just can't see it because of time dilation?

There is only a few question about exploding black holes but that does not address my question. Can a black hole explode? Is there a relationship between Black Holes and the Big Bang? Did the Big Bang ...
Árpád Szendrei's user avatar
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Wormholes on Kruskal-Szekeres coordinates

Kruskal-Szekeres coordinates in the diagram are $$v=\Big(\frac{r}{2M}-1\Big)^{1/2}e^{r/4M}\sinh\Big(\frac{t}{4M}\Big)$$ $$u=\Big(\frac{r}{2M}-1\Big)^{1/2}e^{r/4M}\cosh\Big(\frac{t}{4M}\Big)$$ Region-$\...
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Near a white hole, what do lightcones look like?

In the vicinity of a Schwarzchild black hole, spacetime looks like this (at least according to a quick google search). Here, the centre of the black hole is supposed to be at $x=0$ and the event ...
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Advanced/Retarded Eddington-Finkelstein coordinates & Black/White Holes

The Schwarzschild spacetime is described by $$ds^2=-(1-\frac{r^*}{r})c^2dt^2+(1-\frac{r^*}{r})^{-1}dr^2+r^2d\theta^2+r^2\sin^2\theta d\phi^2,$$ where $r^*$ is the Schwarzschild radius. The advanced ...
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Can white holes undergo hawking radiations like black hole?

Could white holes undergo reverse hawking radiation? This is because of quantum mechanical uncertainty. So for example a pair of particles one a positive and one a negative energy particle. The ...
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What would happen if a black hole swallowed a white hole? [duplicate]

I’m just curious on this, if you can tell me then please do. Also don’t shame me for my bad question I’m just a curious little fella!
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White holes and trans-Planckian NEC instabilities

According to some recent work by Carlo Rovelli, Planckian white holes are effectively immune to perturbations, due to the fact that any perturbations that could destabilize them would have to be ...
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Do colliding black holes violate time reversal symmetry?

Two black holes can collide and merge into one bigger black hole, but not split into two. Does this mean colliding black holes violate time reversal symmetry? Related: Do black holes violate T-...
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The physical interpretation of the trip inside Kerr (black hole) spacetime

Consider then the Kerr metric$[1]$: $$ds^{2} = -\Bigg(1-\frac{2Mr}{\rho^2}\Bigg)dt^2 - \frac{2Marsin^2(\theta)}{\rho^2}[dt d\phi+d\phi dt] +$$ $$+\frac{\rho^2}{\Delta}dr^2+\rho^2d\theta^2+ \frac{sin^...
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What is a Past Event Horizon?

I've recently been informed about a few things from a reliable source: 1) Wormholes can't form via gravitational collapse 2) The event horizons in an ER bridge can't collide I understand what a ...
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Falling to a white hole

White holes, if they exist (unlikely but still fun to think about), are regions of space that can't be entered. They are time-reversals of black holes (GR is time-symmetric). However, a time reversal ...
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If the Universe were a white hole, how would inflation fit in

So, I was thinking about white holes and one theory in particular about white holes, and that is that white holes, the theoretical opposite of black holes, are each "Big Bangs". That is to say on the ...
Curious Layman's user avatar
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Any theory/author using the white hole model to explain the birth of the universe?

The maximally extended Schwarzschild solution (Kruskal diagram) envisages a white hole, which is the time-reverse of a black hole, i.e. a part of spacetime from which things can escape to us, while we ...
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A few questions about white holes

White holes are seen in the maximally extended Schwarzschild solution, they are a region from the past that appear in the theory of eternal black holes, where the singularity exists in both infinite ...
Doctor Electron's user avatar
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Could you extract energy from a rotational white hole?

I understand it is possible to do it in a black hole, and its also possible to reach the event horizon of a black hole and increase its size. But in a white hole, no wave (electromagnetic or ...
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What change of coordinates makes a black hole an De Sitter space with a white hole at the other side?

I have seen that Jean-Pierre Petit describes a change in coordinates for the exterior schwarschild solution that connects two minkowski flat spaces: https://www.jp-petit.org/papers/cosmo/2015-...
Manuel's user avatar
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On the death and rebirth of universe in a black hole

Suppose in the end there will remain only one very large black hole, others have died. Now this black hole had absorbed all the matter and energy of the universe due to conservation principle. ...
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Is the Universe inside the event horizon of a white hole or a black hole or none? [duplicate]

I have read this question: Is the observable universe analogous to a white hole? But it does not have a satisfying answer. And this one: Is the observable region of the universe within the event ...
Árpád Szendrei's user avatar
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Could a black hole and a white hole cause gravitational waves, if orbiting one another?

I have been puzzled by an idea that I came across while reading about white holes. But I've only just started learning about white holes, so my knowledge is severely limited. It seems I also can't ...
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Can mass still be observed in our universe after moving from a black-hole to a white-hole?

This question is based on the recent papers on LQG black-holes by Abhay Ashtekar. Quantum extension of the Kruskal spacetime and Quantum Transfiguration by Kruskal Black Holes When mass moves from ...
Lauren ten Hoor's user avatar