<blockquote>
  <p>Can blackholes be both <a href="https://en.wikipedia.org/wiki/White_hole" rel="nofollow noreferrer">white</a> and <a href="https://en.wikipedia.org/wiki/Black_hole" rel="nofollow noreferrer">black</a>?</p>
</blockquote>

<p>The white hole is the end-life of a black hole, the (as you call it) <em>grey</em> area is the tunnelling.</p>

<p>Many dispute the existence of white holes, described inaccurately (briefly) as a black hole partly reversed. A credible explanation from highly regarded sources is given in the paper: "<a href="https://arxiv.org/abs/1802.04264" rel="nofollow noreferrer">White Holes as Remnants: A Surprising Scenario for the End of a Black Hole</a>" by Eugenio Bianchi, Marios Christodoulou, Fabio D'Ambrosio, Hal M. Haggard, Carlo Rovelli, (Submitted on 12 Feb 2018 (v1), last revised 17 Mar 2018 (this version, v2)):</p>

<p>Briefly:</p>

<blockquote>
  <p>"Quantum tunneling of a black hole into a white hole provides a model for the full life cycle of a black hole. The white hole acts as a long-lived remnant, solving the black-hole information paradox. The remnant solution of the paradox has long been viewed with suspicion, mostly because remnants seemed to be such exotic objects. We point out that (i) established physics includes objects with precisely the required properties for remnants: white holes with small masses but large finite interiors; (ii) non-perturbative quantum-gravity indicates that a black hole tunnels precisely into such a white hole, at the end of its evaporation. We address the objections to the existence of white-hole remnants, discuss their stability, and show how the notions of entropy relevant in this context allow them to evade several no-go arguments. A black hole’s formation, evaporation,
  tunneling to a white hole, and final slow decay, form a unitary process that does not violate any known physics.".</p>
</blockquote>



<blockquote>
  <p>Depending on the angle you view a black hole could it appear white, black or grey? I understand that matter goes in from the side and particles come out the top.</p>
</blockquote>

<p>No, that is something entirely different, nothing to do with a "white hole".</p>

<p>If you first divide black holes into two categories based on rotation you have a <a href="https://en.wikipedia.org/wiki/Schwarzschild_metric#Singularities_and_black_holes" rel="nofollow noreferrer">Schwarzschild black hole</a> (non-rotating) and a <a href="https://en.wikipedia.org/wiki/Frame-dragging#Astronomical_evidence" rel="nofollow noreferrer">Kerr black hole</a> (rotation speed &gt; 0).</p>

<p>A rapidly rotating black hole has an <a href="https://en.wikipedia.org/wiki/Ergosphere" rel="nofollow noreferrer">ergosphere</a> that dips within the Schwarzchild radius:</p>

<blockquote>
  <p>"The equatorial (maximum) radius of an ergosphere corresponds to the Schwarzschild radius of a non-rotating black hole; the polar (minimum) radius can be as little as half the Schwarzschild radius (the radius of a non-rotating black hole) in the case that the black hole is rotating maximally (at higher rotation rates the black hole could not have formed).".</p>
</blockquote>

<p>It is because of that reason that <a href="https://en.wikipedia.org/wiki/Astrophysical_jet#Relativistic_jet" rel="nofollow noreferrer">relativistic jets</a> eject matter from the poles. This is not visible light. It's not a white or grey hole, it's still a black hole.</p>

<p>Due to a number of close votes coming in I will post this brief answer before I'm locked out.</p>

CC BY-SA 4.0
2018-12-28T05:43:31.307Z
2018-12-28T05:43:31.307Z
Rob
<p>Depending on the angle you view a black hole could it appear white, black or grey? Excluding how the <a href="https://physics.stackexchange.com/questions/297890/rainbow-blackhole?r=SearchResults&amp;s=1%7C94.6884">gravitational lensing would make all the light emitted either red or blue shifted creating a rainbow effect</a> from the accretion disk from and remove all the other light sources. </p>

<p>Could a black hole appear black from the side where matter enters and white from the top where the jet is emitted? </p>

<p><a href="https://i.sstatic.net/E0ztI.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/E0ztI.jpg" alt="enter image description here"></a></p>

<p><a href="http://www.physics.utah.edu/~bromley/blackhole/index.html" rel="nofollow noreferrer">http://www.physics.utah.edu/~bromley/blackhole/index.html</a></p>

<p><a href="https://physics.stackexchange.com/questions/207317/could-the-black-hole-in-the-center-of-the-galaxy-be-a-white-hole/207379#207379">https://physics.stackexchange.com/questions/207317/could-the-black-hole-in-the-center-of-the-galaxy-be-a-white-hole/207379#207379</a></p>

CC BY-SA 4.0
2018-12-28T00:17:53.980Z
Your question stems from a major misunderstanding. Why do you think matter goes in from the side and out from the top? Voting to close.
Rory Alsop
CC BY-SA 4.0
2018-12-28T01:25:22.663Z
Nearly every portion of this question is incorrect, or based on misconceptions.  There is nothing to answer here, therefore voting to close.
Dmitry Brant
CC BY-SA 4.0
2018-12-28T05:13:08.017Z
Muze, you’ve been around SE long enough to understand the value of some basic research. Surely you could have re-read the Wikipedia page on black holes first, which would have cleared up your utter misunderstanding of how black holes work. I’m voting to close.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2018-12-28T05:23:49.410Z
PS you also seem to have misunderstood the answers to your linked Physics.SE question, both of which categorically rejected your idea that gravitational lensing creates a rainbow effect. You should edit your current question to make this clear.
Chappo Hasn't Forgotten
<black-hole><white-hole>
Can blackholes appear white and black?
Muze
# Can blackholes appear white and black?

(Asked by: username_0 on 2018-12-27)

Depending on the angle you view a black hole could it appear white, black or grey? Excluding how the [gravitational lensing would make all the light emitted either red or blue shifted creating a rainbow effect](https://physics.stackexchange.com/questions/297890/rainbow-blackhole?r=SearchResults&s=1%7C94.6884) from the accretion disk from and remove all the other light sources.

Could a black hole appear black from the side where matter enters and white from the top where the jet is emitted?

[![enter image description here](https://i.sstatic.net/E0ztI.jpg)](https://i.sstatic.net/E0ztI.jpg)

<http://www.physics.utah.edu/~bromley/blackhole/index.html>

<https://physics.stackexchange.com/questions/207317/could-the-black-hole-in-the-center-of-the-galaxy-be-a-white-hole/207379#207379>

**Tags:** black-hole, white-hole
> **Comments:**
> **username_1**: Your question stems from a major misunderstanding. Why do you think matter goes in from the side and out from the top? Voting to close.  
> **username_2**: Nearly every portion of this question is incorrect, or based on misconceptions.  There is nothing to answer here, therefore voting to close.  
> **username_3**: Muze, you’ve been around SE long enough to understand the value of some basic research. Surely you could have re-read the Wikipedia page on black holes first, which would have cleared up your utter misunderstanding of how black holes work. I’m voting to close.  
> **username_3**: PS you also seem to have misunderstood the answers to your linked Physics.SE question, both of which categorically rejected your idea that gravitational lensing creates a rainbow effect. You should edit your current question to make this clear.  

---

## 1 answers

### Answer by username_4 on 2018-12-28. Score: 2 | Accepted answer

> Can blackholes be both [white](https://en.wikipedia.org/wiki/White_hole) and [black](https://en.wikipedia.org/wiki/Black_hole)?

The white hole is the end-life of a black hole, the (as you call it) *grey* area is the tunnelling.

Many dispute the existence of white holes, described inaccurately (briefly) as a black hole partly reversed. A credible explanation from highly regarded sources is given in the paper: "[White Holes as Remnants: A Surprising Scenario for the End of a Black Hole](https://arxiv.org/abs/1802.04264)" by Eugenio Bianchi, Marios Christodoulou, Fabio D'Ambrosio, Hal M. Haggard, Carlo Rovelli, (Submitted on 12 Feb 2018 (v1), last revised 17 Mar 2018 (this version, v2)):

Briefly:

> "Quantum tunneling of a black hole into a white hole provides a model for the full life cycle of a black hole. The white hole acts as a long-lived remnant, solving the black-hole information paradox. The remnant solution of the paradox has long been viewed with suspicion, mostly because remnants seemed to be such exotic objects. We point out that (i) established physics includes objects with precisely the required properties for remnants: white holes with small masses but large finite interiors; (ii) non-perturbative quantum-gravity indicates that a black hole tunnels precisely into such a white hole, at the end of its evaporation. We address the objections to the existence of white-hole remnants, discuss their stability, and show how the notions of entropy relevant in this context allow them to evade several no-go arguments. A black hole’s formation, evaporation,
> tunneling to a white hole, and final slow decay, form a unitary process that does not violate any known physics.".

> Depending on the angle you view a black hole could it appear white, black or grey? I understand that matter goes in from the side and particles come out the top.

No, that is something entirely different, nothing to do with a "white hole".

If you first divide black holes into two categories based on rotation you have a [Schwarzschild black hole](https://en.wikipedia.org/wiki/Schwarzschild_metric#Singularities_and_black_holes) (non-rotating) and a [Kerr black hole](https://en.wikipedia.org/wiki/Frame-dragging#Astronomical_evidence) (rotation speed > 0).

A rapidly rotating black hole has an [ergosphere](https://en.wikipedia.org/wiki/Ergosphere) that dips within the Schwarzchild radius:

> "The equatorial (maximum) radius of an ergosphere corresponds to the Schwarzschild radius of a non-rotating black hole; the polar (minimum) radius can be as little as half the Schwarzschild radius (the radius of a non-rotating black hole) in the case that the black hole is rotating maximally (at higher rotation rates the black hole could not have formed).".

It is because of that reason that [relativistic jets](https://en.wikipedia.org/wiki/Astrophysical_jet#Relativistic_jet) eject matter from the poles. This is not visible light. It's not a white or grey hole, it's still a black hole.

Due to a number of close votes coming in I will post this brief answer before I'm locked out.


---

