<p>One other supernovae-like but not a supernovae is a tidal disruption event. If a star passes close enough to a black hole it can be fully disrupted into a stream of gas. As the material passes its closest approach to the black hole it can be compressed and ignited. The resulting explosion will be very bright, like a supernovae, but looks different to a normal supernovae.</p>

CC BY-SA 4.0
2019-05-27T00:58:42.350Z
2019-08-03T09:26:44.623Z
2019-08-03T09:26:44.623Z
Rob
<p>I'll try to explain as easiest as possible. It's okay to ask this type of question. It's natural! Okay, when the small star(smaller than our sun) dies, it just becomes a white dwarf. Not even supernova. When the big star dies (bigger than our sun), a supernova occurs. Your question, black hole, is the process AFTER the supernova. If a star is pretty big but not quite that big, it explodes and becomes a neutron star. If a star is GIGANTIC, it becomes a black hole after a supernova.</p>

<p>I'll answer your second question. First, you have to know why a large star becomes a black hole. Do you know why stars can make light itself, like our sun? Because a nuclear fusion is occurring inside the star. If you don't know what nuclear fusion is, you might want to search in youtube (Hydrogen bomb is nuclear fusion bomb). This power is a force that is trying to make stars bigger or pushing forces outward. While the gravity of a star is pushing inward. The shape and size of the stars are stable because these two forces are equal. Stars "die" mean they are out of their fuel to make a nuclear fusion. If the fusion stops, the gravity will overwhelm, which will keep pushes the star inward. If the star is big, the supernova occurs after the shrinkage. Just imagine, if a massive star became infinitely small, its gravity will become infinitely larger. I hope I answered your second question because this process cannot occur in reverse. </p>

CC BY-SA 4.0
2019-05-27T03:25:53.097Z
2019-05-27T03:25:53.097Z
Kevin Lee
<p>No, it cannot. A black hole is something vastly different from a star. It's vastly different from anything else. It's not a thing, really, but more like a portion of very distorted spacetime. Nothing escapes from it simply because there is no way out - spacetime is distorted in such a way that all trajectories lead to the center.</p>

<p>Now, there is a mechanism where radiation is generated just outside the black hole, sucking energy from its gravitational field and therefore from its mass. This is called Hawking radiation. It does not come from inside the BH, but the way it's created it leeches the BH's energy / mass. In time, this would diminish the mass of the BH.</p>

<p>It turns out, the smaller the BH, the stronger the Hawking radiation. This in turn makes the BH lose weight even faster, so the HR gets even stronger, and so on. It's a vicious cycle. If the black hole is small enough, the process turns into an explosion - HR gets so intense, the whole mass of the black hole is converted into radiation at once. It's not a supernova, not as big as that, but it is a powerful explosion.</p>

<p>The only issue here is - HR is very weak when BHs are big. So regular BHs will take an incredibly long time to slim down, if ever, to the tiny size where HR spirals out of control. Basically this never happens in reality.</p>

<p>TLDR: Not a supernova, just a huge bomb, but not very likely.</p>

CC BY-SA 4.0
2019-05-27T07:12:53.420Z
Do we know if any black hole has completely evaporated, or is this event to happen very far in the future given the current age of the universe?
Iván Pérez
CC BY-SA 4.0
2019-05-27T08:06:46.180Z
@IvánPérez Very far in the future. According to the [Hawking radiation calculator](https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator), a black hole 3 times heavier than the Sun (about the smallest possible that can be formed by any known mechanism) takes around $1.787\times 10^{76}$ years to evaporate, far longer than the current age of the universe. OTOH, if small [primordial black holes](https://en.wikipedia.org/wiki/Primordial_black_hole) were created in the early universe, they may be evaporating now (or have already), but such black holes are *very* hypothetical.
PM 2Ring
CC BY-SA 4.0
2019-05-24T22:28:32.317Z
2019-05-24T22:28:32.317Z
Florin Andrei
<p>In layman terms:</p>

<ol>
<li>nothing ever escapes the pull of a black hole, not even light</li>
<li>when a super massive star reaches the end of it's life you get a supernova</li>
<li>sometimes the <em>"remains"</em> of these stars can turn turn into black holes</li>
</ol>

<p>My question is: can a black hole <em>"supernova"</em> the same way a large star does?</p>

<p>What I'm saying is, could this process occur in reverse? <strong>I.E:</strong></p>

<blockquote>
  <p><code>black hole</code> -> <code>supernova</code> -> <code>particles form dust cloud</code> -> <code>new star</code></p>
</blockquote>

<p><strong>EDIT:</strong> Apologies if any of this sounds stupid (or vague), I'm just curious.</p>

<star><black-hole><gravity><supernova><explosion>
Can a black hole "supernova"?
Malekai
# Can a black hole "supernova"?

(Asked by: username_0 on 2019-05-24)

In layman terms:

1. nothing ever escapes the pull of a black hole, not even light
2. when a super massive star reaches the end of it's life you get a supernova
3. sometimes the *"remains"* of these stars can turn turn into black holes

My question is: can a black hole *"supernova"* the same way a large star does?

What I'm saying is, could this process occur in reverse? **I.E:**

> `black hole` -> `supernova` -> `particles form dust cloud` -> `new star`

**EDIT:** Apologies if any of this sounds stupid (or vague), I'm just curious.

**Tags:** star, black-hole, gravity, supernova, explosion


---

## 3 answers

### Answer by username_3 on 2019-05-24. Score: 12 | Accepted answer

No, it cannot. A black hole is something vastly different from a star. It's vastly different from anything else. It's not a thing, really, but more like a portion of very distorted spacetime. Nothing escapes from it simply because there is no way out - spacetime is distorted in such a way that all trajectories lead to the center.

Now, there is a mechanism where radiation is generated just outside the black hole, sucking energy from its gravitational field and therefore from its mass. This is called Hawking radiation. It does not come from inside the BH, but the way it's created it leeches the BH's energy / mass. In time, this would diminish the mass of the BH.

It turns out, the smaller the BH, the stronger the Hawking radiation. This in turn makes the BH lose weight even faster, so the HR gets even stronger, and so on. It's a vicious cycle. If the black hole is small enough, the process turns into an explosion - HR gets so intense, the whole mass of the black hole is converted into radiation at once. It's not a supernova, not as big as that, but it is a powerful explosion.

The only issue here is - HR is very weak when BHs are big. So regular BHs will take an incredibly long time to slim down, if ever, to the tiny size where HR spirals out of control. Basically this never happens in reality.

TLDR: Not a supernova, just a huge bomb, but not very likely.

> **Comments:**
> **username_4**: Do we know if any black hole has completely evaporated, or is this event to happen very far in the future given the current age of the universe?  
> **username_5**: @IvánPérez Very far in the future. According to the [Hawking radiation calculator](https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator), a black hole 3 times heavier than the Sun (about the smallest possible that can be formed by any known mechanism) takes around $1.787\times 10^{76}$ years to evaporate, far longer than the current age of the universe. OTOH, if small [primordial black holes](https://en.wikipedia.org/wiki/Primordial_black_hole) were created in the early universe, they may be evaporating now (or have already), but such black holes are *very* hypothetical.  

---

### Answer by username_1 on 2019-05-27. Score: 4

One other supernovae-like but not a supernovae is a tidal disruption event. If a star passes close enough to a black hole it can be fully disrupted into a stream of gas. As the material passes its closest approach to the black hole it can be compressed and ignited. The resulting explosion will be very bright, like a supernovae, but looks different to a normal supernovae.


---

### Answer by username_2 on 2019-05-27. Score: 0

I'll try to explain as easiest as possible. It's okay to ask this type of question. It's natural! Okay, when the small star(smaller than our sun) dies, it just becomes a white dwarf. Not even supernova. When the big star dies (bigger than our sun), a supernova occurs. Your question, black hole, is the process AFTER the supernova. If a star is pretty big but not quite that big, it explodes and becomes a neutron star. If a star is GIGANTIC, it becomes a black hole after a supernova.

I'll answer your second question. First, you have to know why a large star becomes a black hole. Do you know why stars can make light itself, like our sun? Because a nuclear fusion is occurring inside the star. If you don't know what nuclear fusion is, you might want to search in youtube (Hydrogen bomb is nuclear fusion bomb). This power is a force that is trying to make stars bigger or pushing forces outward. While the gravity of a star is pushing inward. The shape and size of the stars are stable because these two forces are equal. Stars "die" mean they are out of their fuel to make a nuclear fusion. If the fusion stops, the gravity will overwhelm, which will keep pushes the star inward. If the star is big, the supernova occurs after the shrinkage. Just imagine, if a massive star became infinitely small, its gravity will become infinitely larger. I hope I answered your second question because this process cannot occur in reverse.


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