<p>Interestingly enough, Neil deGrasse Tyson, <a href="http://en.wikipedia.org/wiki/Neil_deGrasse_Tyson" rel="nofollow">an american astrophysicist</a>, wrote a book titled <a href="http://rads.stackoverflow.com/amzn/click/0393330168" rel="nofollow"><strong>Death by black hole</strong></a>.</p>

<p>In <a href="http://fora.tv/2008/02/19/Neil_DeGrasse_Tyson_Death_by_Black_Hole" rel="nofollow">this video</a> he goes on to explain the details of what you asked, the subjective experience of the astronaut being sucked into the black hole. <strong>It is definitely painful!</strong></p>

CC BY-SA 3.0
2013-12-19T08:58:11.993Z
I disagree that it would be painful. You'd lose consciousness long before you'd feel pain due to gravity gradient stretching your body, because you'd lose intracranial fluids, lose consciousness and consequently die (pretty fast).
TildalWave
CC BY-SA 3.0
2013-12-19T09:33:51.217Z
Yeah, it seems reasonable that if you can feel a gravity gradient, blood would be pooling in your feet (assuming "head-up"), to some degree, eventually knocking you out. Whether the gradient is painful before then is up for debate perhaps? But how long a delay would the taller experience between these events is what I'm particularly interested in.
aaaidan
CC BY-SA 3.0
2013-12-19T09:37:12.843Z
Neil seems to think the gradient would be strong enough to snap a human spine before death, but I am dubious that he's not showboating a little...
aaaidan
CC BY-SA 3.0
2013-12-19T13:58:19.433Z
I wouldn't be so quick to say he's wrong, after all, he wrote a book on the subject and did a thorough investigation followed by an extensive analysis. I bet he know a lot more about black holes than we do.
Eduardo Serra
CC BY-SA 3.0
2013-12-19T15:19:28.180Z
Thanks for the information, but in the context of *this* site, it would be better to provide an answer here.  It's okay to add links for further reading, but this site was created to build a definitive collection of ***answers*** to astronomy questions. When someone comes here looking for answers through search, the last thing we should be doing is sending them *elsewhere* to find that information. Link-only answers do little more than add another barrier between future readers and the actual information they are looking for. That's not making the Internet better.
Robert Cartaino
CC BY-SA 3.0
2013-12-19T17:11:51.570Z
All right, I'll have it mind for future posts.
Eduardo Serra
CC BY-SA 3.0
2013-12-18T19:27:11.963Z
2013-12-18T19:27:11.963Z
Eduardo Serra
<p>For some "average sized" black hole, how long would it take for a distant (spacesuit-wearing!) astronaut to:</p>

<ul>
<li>be able to see the gravitational lensing with the naked eye </li>
<li>clearly feel the gravity gradient</li>
<li>reach a lethal gravity gradient</li>
<li>cross the event horizon</li>
</ul>

<p>Ultimately I'm interested in the subjective experience of a human falling into a black hole. Would it be drawn out and unpleasant? Or is it that by the time the gradient would be painful, there'd be barely any time at all before annihilation?</p>

CC BY-SA 3.0
2013-12-18T04:26:58.647Z
Actually, this is a problem I remember doing in my cosmology class. There are some really good questions here having to do with proper time versus coordinate time, the relationship between the mass of the black hole and the gradient of its gravitational field, and a few other things. If I find some quantitative calculations I remember doing I'll try to answer the question.
astromax
CC BY-SA 3.0
2013-12-18T04:32:54.950Z
I think this type of question is perfectly suited for this type of site. It has everything to do with General Relativity and Cosmology.
astromax
CC BY-SA 3.0
2013-12-18T04:35:34.583Z
Thanks @astromax, would appreciate an attempt at an answer, and cheers for a counter opinion on this question's appropriateness.
aaaidan
CC BY-SA 3.0
2013-12-18T04:35:52.553Z
I had imagined the mass of the black hole might even change the order of some of the events I listed in the question. @TidalWave suggests that you'd necessarily be dead by the time you cross the event horizon (if that's appropriate usage of that phrase...), but I wondered if a black hole could be big enough to have only a slight gradient at that point. Even if only in theory...
aaaidan
CC BY-SA 3.0
2013-12-18T04:39:25.473Z
Yes - the conclusion I remember coming to is that the larger the black hole mass the closer you could come to the event horizon without feeling this differential tug between your head and your feet. The smaller mass black holes are actually the more lethal ones in terms of tidal forces as you approach the event horizon. However, the amount of time it takes you to get to the event horizon as seen from an "outsider" if I'm not mistaken is infinite. I'll have to double check to see if that's actually the case.
astromax
CC BY-SA 3.0
2013-12-18T04:42:18.637Z
I'm actually teaching a cosmology class next term. One of the homework sets assigned I believe has this particular question. I'll post the answer when I figure it out.
astromax
CC BY-SA 3.0
2013-12-18T08:10:10.650Z
For posterity, details about this question, including its suitability for this site was discussed here: http://chat.stackexchange.com/transcript/message/12712199#12712199
aaaidan
CC BY-SA 3.0
2013-12-18T13:30:32.390Z
This is a question asked many times on Physics SE
Alexey Bobrick
CC BY-SA 3.0
2013-12-18T16:01:41.287Z
I calculated questions 2/3 for a super-massive black hole once; it's still up on physics: http://physics.stackexchange.com/questions/38837/spaghettification-of-humans-near-black-holes - maybe that helps. (tidal forces can be painful, ouch)
Alexander Janssen
<black-hole>
Timeline of falling into a blackhole
aaaidan
# Timeline of falling into a blackhole

(Asked by: username_0 on 2013-12-17)

For some "average sized" black hole, how long would it take for a distant (spacesuit-wearing!) astronaut to:

* be able to see the gravitational lensing with the naked eye
* clearly feel the gravity gradient
* reach a lethal gravity gradient
* cross the event horizon

Ultimately I'm interested in the subjective experience of a human falling into a black hole. Would it be drawn out and unpleasant? Or is it that by the time the gradient would be painful, there'd be barely any time at all before annihilation?

**Tags:** black-hole
> **Comments:**
> **username_1**: Actually, this is a problem I remember doing in my cosmology class. There are some really good questions here having to do with proper time versus coordinate time, the relationship between the mass of the black hole and the gradient of its gravitational field, and a few other things. If I find some quantitative calculations I remember doing I'll try to answer the question.  
> **username_1**: I think this type of question is perfectly suited for this type of site. It has everything to do with General Relativity and Cosmology.  
> **username_0**: Thanks @astromax, would appreciate an attempt at an answer, and cheers for a counter opinion on this question's appropriateness.  
> **username_0**: I had imagined the mass of the black hole might even change the order of some of the events I listed in the question. @TidalWave suggests that you'd necessarily be dead by the time you cross the event horizon (if that's appropriate usage of that phrase...), but I wondered if a black hole could be big enough to have only a slight gradient at that point. Even if only in theory...  
> **username_1**: Yes - the conclusion I remember coming to is that the larger the black hole mass the closer you could come to the event horizon without feeling this differential tug between your head and your feet. The smaller mass black holes are actually the more lethal ones in terms of tidal forces as you approach the event horizon. However, the amount of time it takes you to get to the event horizon as seen from an "outsider" if I'm not mistaken is infinite. I'll have to double check to see if that's actually the case.  
> **username_1**: I'm actually teaching a cosmology class next term. One of the homework sets assigned I believe has this particular question. I'll post the answer when I figure it out.  
> **username_0**: For posterity, details about this question, including its suitability for this site was discussed here: http://chat.stackexchange.com/transcript/message/12712199#12712199  
> **username_2**: This is a question asked many times on Physics SE  
> **username_3**: I calculated questions 2/3 for a super-massive black hole once; it's still up on physics: http://physics.stackexchange.com/questions/38837/spaghettification-of-humans-near-black-holes - maybe that helps. (tidal forces can be painful, ouch)  

---

## 1 answers

### Answer by username_4 on 2013-12-18. Score: 2

Interestingly enough, Neil deGrasse Tyson, [an american astrophysicist](http://en.wikipedia.org/wiki/Neil_deGrasse_Tyson), wrote a book titled [**Death by black hole**](http://rads.stackoverflow.com/amzn/click/0393330168).

In [this video](http://fora.tv/2008/02/19/Neil_DeGrasse_Tyson_Death_by_Black_Hole) he goes on to explain the details of what you asked, the subjective experience of the astronaut being sucked into the black hole. **It is definitely painful!**

> **Comments:**
> **username_5**: I disagree that it would be painful. You'd lose consciousness long before you'd feel pain due to gravity gradient stretching your body, because you'd lose intracranial fluids, lose consciousness and consequently die (pretty fast).  
> **username_0**: Yeah, it seems reasonable that if you can feel a gravity gradient, blood would be pooling in your feet (assuming "head-up"), to some degree, eventually knocking you out. Whether the gradient is painful before then is up for debate perhaps? But how long a delay would the taller experience between these events is what I'm particularly interested in.  
> **username_0**: Neil seems to think the gradient would be strong enough to snap a human spine before death, but I am dubious that he's not showboating a little...  
> **username_4**: I wouldn't be so quick to say he's wrong, after all, he wrote a book on the subject and did a thorough investigation followed by an extensive analysis. I bet he know a lot more about black holes than we do.  
> **username_6**: Thanks for the information, but in the context of *this* site, it would be better to provide an answer here.  It's okay to add links for further reading, but this site was created to build a definitive collection of ***answers*** to astronomy questions. When someone comes here looking for answers through search, the last thing we should be doing is sending them *elsewhere* to find that information. Link-only answers do little more than add another barrier between future readers and the actual information they are looking for. That's not making the Internet better.  
> **username_4**: All right, I'll have it mind for future posts.  

---

