<p>From the Oxford English Dictionary:</p>

<blockquote>
  <p>"vicinity" just means "the area near to or surrounding a place" </p>
</blockquote>

<p>so "in the vicinity of a black hole" just means "near to a black hole." </p>

<p>Other dictionaries say "immediately next to" so in response to your comment about vagueness, treat vicinity as the immediate neighbourhood of the black hole. You will not find an exact meaning - it is used as it is in English. There is no specific distance measurement. You don't have a distance from radius which would stop being in the vicinity.</p>

CC BY-SA 4.0
2019-01-04T15:25:04.177Z
thank you for your answer, but I'm searching the exact meaning in black hole text, not as a normal word in English. "near", means exactly until where from a BH I can use this word?
Schok
CC BY-SA 4.0
2019-01-04T15:32:16.500Z
You will not find an exact meaning - it is used as it is in English. There is no specific distance measurement.
Rory Alsop
CC BY-SA 4.0
2019-01-04T15:21:15.720Z
2019-01-04T15:32:45.343Z
2019-01-04T15:32:45.343Z
Rory Alsop
<p>What is the exact meaning of vicinity of Blackhole or a disk? Is this the same as inside the horizon for black holes? If so, why people don't say inside of BH, simply. What is the difference?</p>

<p>I use this phrase actually! and it may seem obvious but not to me, please somebody make it clear. I searched but I couldn't find an exact answer.</p>

<p>Edited: Until which radius from Blackhole I can use this word meaningfully? It's not clear to me its astronomical dimension. "near" is not enough to me. If it could be inside a horizon and also outside of it, it makes a huge difference from point of view of the observer at infinity, as you know, how I can call them by the same name and sometimes I mean one sometimes the other one. </p>

CC BY-SA 4.0
2019-01-04T15:17:47.407Z
The phrase "in the vicinity of a black hole" just means near a black hole, and normally outside the event horizon, but that can depend on the context. What sort of disk are you talking about?
PM 2Ring
CC BY-SA 4.0
2019-01-04T15:21:08.677Z
@ PM 2Ring, thank you for your answer. If I take it as outside the horizon until where? ISCO? "near" is kind of vague to me. also, about the disk, I mean for  accretion disks, because in some texts always see this pharse "in the visinity of disk".
Schok
CC BY-SA 4.0
2019-01-04T15:32:30.177Z
Please add that information to your question. And explain what ISCO means. Yes, "vicinity" is a bit vague, so it should only be used when a vague description of location is sufficient. If you have trouble with a particular passage from a text, then you can quote it in your question and of course give a reference to the text it comes from). That will make it easier to give a more definite answer, once we can see the context.
PM 2Ring
CC BY-SA 4.0
2019-01-04T15:40:40.973Z
@Pm 2Ring: ISCO means the last stable orbit of photon near a BH. always we hear this word, in papers, in class, in seminars. I want to know where I can use it meaningfully.
Schok
CC BY-SA 4.0
2019-01-05T01:24:41.307Z
Someone has flagged this question for closure as "unclear", but it seems clear enough to me: the OP wants to know if "vicinity" has an exact astronomical dimension. It's not a *good* question but it's a valid one. I'm voting to leave it open.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-01-07T12:00:19.383Z
@Chappo, Thank you for your comment. But still, it's not clear to me its astronomical dimension. If it could be inside a horizon and also outside of it, it makes a huge difference from point of view of the observer at infinity, as you know. I don't mind if this is not a good question but I want the answer, please.
Schok
CC BY-SA 4.0
2019-01-07T13:14:01.663Z
@Schok the answer has already been provided - **there is no exact meaning**. That's the answer. "Vicinity" means "nearby". Most would interpret the vicinity of a black hole to be *outside* the horizon, since anything on the "inside" is beyond observation, but "vicinity" might mean within metres of the horizon or it might mean within a light year - it depends on the context.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-01-07T13:43:15.980Z
@Chappo, Thank you, now it's a little more clear to me, because of the reason that you mention about observation.
Schok
<black-hole><space-time><general-relativity><accretion-discs>
What is the exact meaning of vicinity of Black hole or a disk? the same as inside?
Schok
# What is the exact meaning of vicinity of Black hole or a disk? the same as inside?

(Asked by: username_0 on 2019-01-04)

What is the exact meaning of vicinity of Blackhole or a disk? Is this the same as inside the horizon for black holes? If so, why people don't say inside of BH, simply. What is the difference?

I use this phrase actually! and it may seem obvious but not to me, please somebody make it clear. I searched but I couldn't find an exact answer.

Edited: Until which radius from Blackhole I can use this word meaningfully? It's not clear to me its astronomical dimension. "near" is not enough to me. If it could be inside a horizon and also outside of it, it makes a huge difference from point of view of the observer at infinity, as you know, how I can call them by the same name and sometimes I mean one sometimes the other one.

**Tags:** black-hole, space-time, general-relativity, accretion-discs

> **Comments:**
> **username_1**: The phrase "in the vicinity of a black hole" just means near a black hole, and normally outside the event horizon, but that can depend on the context. What sort of disk are you talking about?  
> **username_0**: @ username_1, thank you for your answer. If I take it as outside the horizon until where? ISCO? "near" is kind of vague to me. also, about the disk, I mean for  accretion disks, because in some texts always see this pharse "in the visinity of disk".  
> **username_1**: Please add that information to your question. And explain what ISCO means. Yes, "vicinity" is a bit vague, so it should only be used when a vague description of location is sufficient. If you have trouble with a particular passage from a text, then you can quote it in your question and of course give a reference to the text it comes from). That will make it easier to give a more definite answer, once we can see the context.  
> **username_0**: @Pm 2Ring: ISCO means the last stable orbit of photon near a BH. always we hear this word, in papers, in class, in seminars. I want to know where I can use it meaningfully.  
> **username_2**: Someone has flagged this question for closure as "unclear", but it seems clear enough to me: the OP wants to know if "vicinity" has an exact astronomical dimension. It's not a *good* question but it's a valid one. I'm voting to leave it open.  
> **username_0**: @Chappo, Thank you for your comment. But still, it's not clear to me its astronomical dimension. If it could be inside a horizon and also outside of it, it makes a huge difference from point of view of the observer at infinity, as you know. I don't mind if this is not a good question but I want the answer, please.  
> **username_2**: @username_0 the answer has already been provided - **there is no exact meaning**. That's the answer. "Vicinity" means "nearby". Most would interpret the vicinity of a black hole to be *outside* the horizon, since anything on the "inside" is beyond observation, but "vicinity" might mean within metres of the horizon or it might mean within a light year - it depends on the context.  
> **username_0**: @Chappo, Thank you, now it's a little more clear to me, because of the reason that you mention about observation.  

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## 1 answers

### Answer by username_3 on 2019-01-04. Score: 3

From the Oxford English Dictionary:

> "vicinity" just means "the area near to or surrounding a place"

so "in the vicinity of a black hole" just means "near to a black hole."

Other dictionaries say "immediately next to" so in response to your comment about vagueness, treat vicinity as the immediate neighbourhood of the black hole. You will not find an exact meaning - it is used as it is in English. There is no specific distance measurement. You don't have a distance from radius which would stop being in the vicinity.

> **Comments:**
> **username_0**: thank you for your answer, but I'm searching the exact meaning in black hole text, not as a normal word in English. "near", means exactly until where from a BH I can use this word?  
> **username_3**: You will not find an exact meaning - it is used as it is in English. There is no specific distance measurement.  

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