Register to reply

What events occur inside a black hole?

by F1225
Tags: black hole, light, relativity
Share this thread:
F1225
#1
Nov23-12, 11:19 PM
P: 18
As we know, the gravitational pull of the black hole is too strong, not even light can escape from it...


Let me assume 2 person: A and B
A is sucked into a black hole while B is outside the event horizon...
At first, B will notice that A has disappeared due to the lights(image) of A is sucked by the black hole...
On the other hand, A will still see the image of B because the lights(image) of B is being sucked into the black hole.

What this all mean? Do this event relates to relativity which both of them are in different inertial frame causing things which they observed to differs?


Thanks for spending your time reading the entire post...*(it's quite long)...haha
Phys.Org News Partner Science news on Phys.org
Sapphire talk enlivens guesswork over iPhone 6
Geneticists offer clues to better rice, tomato crops
UConn makes 3-D copies of antique instrument parts
phinds
#2
Nov23-12, 11:48 PM
PF Gold
phinds's Avatar
P: 6,101
Quote Quote by F1225 View Post
As we know, the gravitational pull of the black hole is too strong, not even light can escape from it...


Let me assume 2 person: A and B
A is sucked into a black hole while B is outside the event horizon...
At first, B will notice that A has disappeared due to the lights(image) of A is sucked by the black hole...
On the other hand, A will still see the image of B because the lights(image) of B is being sucked into the black hole.

What this all mean? Do this event relates to relativity which both of them are in different inertial frame causing things which they observed to differs?
Person B will NOT see A sucked into the black hole, he will see A move more and more slowly as A approaches the event horizon of the BH. That isn't what actually happen to A of course, but it is what B will see. A will just continue on through the EH as though it were not there.

You are correct that A will continue to see B, even after A passes the event horizon
jedishrfu
#3
Nov23-12, 11:49 PM
P: 2,784
my understanding is that A will appear to hover on the event horizon and will never be observed falling in. From A's perspective though, A will pass the event horizon and continue the fall being stretched out like taffy due to gravitational tidal effects.

http://www.slate.com/articles/news_a...lack_hole.html

and in more detail:

http://math.ucr.edu/home/baez/physic...s/fall_in.html

phinds
#4
Nov23-12, 11:57 PM
PF Gold
phinds's Avatar
P: 6,101
What events occur inside a black hole?

Quote Quote by jedishrfu View Post
my understanding is that A will appear to hover on the event horizon and will never be observed falling in. From A's perspective though, A will pass the event horizon and continue the fall being stretched out like taffy due to gravitational tidal effects.
Well, that's not what you said in your original post, thus my answer.

The sphagettification may occur either inside or outside the BH, depending on its size.
jedishrfu
#5
Nov24-12, 12:00 AM
P: 2,784
Quote Quote by phinds View Post
Well, that's not what you said in your original post, thus my answer.

The sphagettification may occur either inside or outside the BH, depending on its size.
I'm confused who are you talking about, I only posted once. ???
phinds
#6
Nov24-12, 12:07 AM
PF Gold
phinds's Avatar
P: 6,101
Quote Quote by jedishrfu View Post
I'm confused who are you talking about, I only posted once. ???
DOH ! Sorry about that. I clearly wasn't paying attention and though you were the OP again.
jedishrfu
#7
Nov24-12, 12:11 AM
P: 2,784
Quote Quote by phinds View Post
DOH ! Sorry about that. I clearly wasn't paying attention and though you were the OP again.
NP, I thought one of us had fallen into that black hole and I wasnt sure which one.
ahhaha
#8
Nov24-12, 07:58 PM
P: 7
No events occur inside a black hole because black holes don't have an interior.
phinds
#9
Nov24-12, 08:03 PM
PF Gold
phinds's Avatar
P: 6,101
Quote Quote by ahhaha View Post
No events occur inside a black hole because black holes don't have an interior.
You are right (according to most theories) but the term "inside a black hole" normally just means "inside the event horizon".
ahhaha
#10
Nov24-12, 09:00 PM
P: 7
"inside the event horizon" can't be made rigorous, if only because the notion of event horizon( assuming it can be made rigorous) is no more rigorous than the notion of BH interior since an event horizon is an asymptotic limit of future null infinity. In the usual OpSnyVolk representation of Schwarz that's where the radial coordinate magically turns into the temporal coordinate. At that point you don't know where you are! Next to nonsense, or in it?
DaleSpam
#11
Nov24-12, 09:39 PM
Mentor
P: 16,965
Quote Quote by ahhaha View Post
"inside the event horizon" can't be made rigorous, if only because the notion of event horizon( assuming it can be made rigorous) is no more rigorous than the notion of BH interior since an event horizon is an asymptotic limit of future null infinity. In the usual OpSnyVolk representation of Schwarz that's where the radial coordinate magically turns into the temporal coordinate. At that point you don't know where you are! Next to nonsense, or in it?
This is incorrect. Inside the event horizon can easily be made rigorous. E.g. The region without a timelike killing vector.

Also, there are several coordinate charts that are well behaved at the EH, so the failure of one is clearly a problem with those coordinates, not the EH itself.
ahhaha
#12
Nov24-12, 10:29 PM
P: 7
Your "region" can't be well defined since its domain is rest of universe. A singularity or BH can only make sense when it's approached from asymptotic spatial infinity and an effective approach may not be complete in the assumed metric. So I would ask you where in the approach is the path without timelike vector?
Nugatory
#13
Nov24-12, 11:35 PM
Sci Advisor
Thanks
P: 3,456
Quote Quote by ahhaha View Post
Your "region" can't be well defined since its domain is rest of universe. A singularity or BH can only make sense when it's approached from asymptotic spatial infinity and an effective approach may not be complete in the assumed metric.
Yes, an effective approach may not be possible in some metrics, but the Schwarzchild metric solution to the Einstein field equations isn't one of these. You just have to transform from the Schwarzchild coordinates to some other coordinates that are better-behaved at the event horizon.

So I would ask you where in the approach is the path without timelike vector?
Dalespam didn't say "without a timelike vector", he said "without a timelike Killing vector". There's no shortage of timelike vectors at and inside the event horizon. The lack of a timelike Killing vector just means that there exists no coordinate system in which the metric components can be independent of time - not too surprising because all timelike geodesics converge on the central singularity.
DaleSpam
#14
Nov25-12, 07:23 AM
Mentor
P: 16,965
Quote Quote by ahhaha View Post
Your "region" can't be well defined since its domain is rest of universe. A singularity or BH can only make sense when it's approached from asymptotic spatial infinity
This is a complete non-sequitor. What do the size of a domain or required approaches have to do with being well-defined? Well defined means only that it has a definition which is unambiguous, not any of the unrelated concepts you are trying to bring in. The term "inside the EH" is well defined.


Quote Quote by ahhaha View Post
and an effective approach may not be complete in the assumed metric. So I would ask you where in the approach is the path without timelike vector?
I don't know what you are trying to say here.


Register to reply

Related Discussions
Does how black holes inside galaxies orbit around the central black hole tell us.. Astronomy & Astrophysics 8
Does spaghettification occur around a super massive black hole? Special & General Relativity 10
Inside a black hole? Astronomy & Astrophysics 16
Black hole inside a larger black hole. Cosmology 33
Question about events inside black holes Special & General Relativity 2