<p>Anything that's inside the event horizon has vanished forever and ever from this universe. There is no way back, period. Once inside, any direction you're turning, you're looking at the center of the BH, there is no direction pointing "out" anymore - that's the real reason why you can't get back out.</p>

<p>The physics inside the event horizon are radically different from the physics in normal space. It's pointless to speculate about fusion, etc. Regardless, what happens inside the event horizon, stays inside the event horizon.</p>

<p>Anything falling towards the event horizon will take an infinite amount of time, from your perspective (the distant observer) to even reach the event horizon.</p>

<p>Just accept it. Once a black hole, always a black hole.</p>

CC BY-SA 4.0
2018-07-17T23:31:49.897Z
2018-07-17T23:31:49.897Z
Florin Andrei
<p>Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder this again:</p>

<p>Question: Once material is absorbed, is there a physical reason why fusion cannot take place once more? Does the process of entering the black hole strip out all the nuclear energy contained in mass/matter? Or is it that matter that makes it past the event horizon has potential to fuse but because of that time dilation due to the already present dense mass make this process take billions of years to resolve? </p>

CC BY-SA 4.0
2018-07-17T22:59:37.723Z
"Some answers"?
ProfRob
CC BY-SA 4.0
2018-07-18T14:48:51.710Z
I'm voting to close this question as off-topic because it calls for idle speculation which contradicts all known physics.
Carl Witthoft
CC BY-SA 4.0
2018-07-19T17:23:47.937Z
@CarlWitthoft Afaik, there is some calculation, what is the maximal speed with what a black hole can suck dense gas herein. If the gas is dense, then the radiation of the infalling matter starts to push the rest away, this makes a limit. Which results, that BH falling into a star would be a gravitationally bound object with self-generated, partially fusional power production. Thus, it would be a star - although probably not a very long living one.
peterh
<star><black-hole><astrophysics><star-formation><time-dilation>
Black-hole becoming a star again - follow-up question
SMF_USR
# Black-hole becoming a star again - follow-up question

(Asked by: username_0 on 2018-07-17)

Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder this again:

Question: Once material is absorbed, is there a physical reason why fusion cannot take place once more? Does the process of entering the black hole strip out all the nuclear energy contained in mass/matter? Or is it that matter that makes it past the event horizon has potential to fuse but because of that time dilation due to the already present dense mass make this process take billions of years to resolve?

**Tags:** star, black-hole, astrophysics, star-formation, time-dilation

> **Comments:**
> **username_1**: "Some answers"?  
> **username_2**: I'm voting to close this question as off-topic because it calls for idle speculation which contradicts all known physics.  
> **username_3**: @CarlWitthoft Afaik, there is some calculation, what is the maximal speed with what a black hole can suck dense gas herein. If the gas is dense, then the radiation of the infalling matter starts to push the rest away, this makes a limit. Which results, that BH falling into a star would be a gravitationally bound object with self-generated, partially fusional power production. Thus, it would be a star - although probably not a very long living one.  

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## 1 answers

### Answer by username_4 on 2018-07-17. Score: 3

Anything that's inside the event horizon has vanished forever and ever from this universe. There is no way back, period. Once inside, any direction you're turning, you're looking at the center of the BH, there is no direction pointing "out" anymore - that's the real reason why you can't get back out.

The physics inside the event horizon are radically different from the physics in normal space. It's pointless to speculate about fusion, etc. Regardless, what happens inside the event horizon, stays inside the event horizon.

Anything falling towards the event horizon will take an infinite amount of time, from your perspective (the distant observer) to even reach the event horizon.

Just accept it. Once a black hole, always a black hole.


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