Is everything else blackhole?

  • Thread starter aaryan0077
  • Start date
  • #1
69
0

Main Question or Discussion Point

Is everything "else" blackhole?

A black hole is something form which it is impossible to escape; even for light, and so no information can reach us form it Except for measuring its gravitational effects it produces, we can't tell that its out there or not.
So it means that if form some 'region' light and so no info can ever reach us, we might at first interpret it as Black hole (we can still consider its a very faint star that light is struggling to reach us, but let's just consider the simple case here), though we'll confirm only after measuring its effects and all.
If now we take out light cone (of which we are a part) and look at the "elsewhere" region, will it be an apparent black hole for us, if only at out first site?
 

Answers and Replies

  • #2
DaveC426913
Gold Member
18,850
2,328


A black hole is something form which it is impossible to escape; even for light, and so no information can reach us form it Except for measuring its gravitational effects it produces, we can't tell that its out there or not.
So it means that if form some 'region' light and so no info can ever reach us, we might at first interpret it as Black hole (we can still consider its a very faint star that light is struggling to reach us, but let's just consider the simple case here), though we'll confirm only after measuring its effects and all.
If now we take out light cone (of which we are a part) and look at the "elsewhere" region, will it be an apparent black hole for us, if only at out first site?
I do not understand what you are describing. What does this mean:

If now we take out light cone (of which we are a part) and look at the "elsewhere" region...
 
  • #3
Fredrik
Staff Emeritus
Science Advisor
Gold Member
10,851
408


He's talking about an ordinary light cone around the event "right here, right now", and is asking if the exterior region can be viewed as a black hole from our point of view, at that event.

The answer is no. Signals from the exterior region (i.e. from events that are spacelike separated from us) can't reach the "right here, right now" event, but they can certainly end up inside our future light cone and even reach our world line.
 

Related Threads on Is everything else blackhole?

Replies
8
Views
3K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
2
Views
276
  • Last Post
Replies
16
Views
454
  • Last Post
Replies
4
Views
661
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
11
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
10
Views
2K
Top