Can a black hole shrink another black hole's event horizon?

Click For Summary

Discussion Overview

The discussion revolves around the behavior of black hole event horizons, specifically whether the event horizon of one black hole can shrink in the presence of another black hole. The conversation includes interpretations of visual representations and the effects of gravitational interactions on the shapes and sizes of event horizons.

Discussion Character

  • Debate/contested, Conceptual clarification, Exploratory

Main Points Raised

  • One participant suggests that the event horizons of black holes have decreased in size as seen in an image, implying that proximity to another black hole could cause shrinking.
  • Another participant questions the conclusion drawn from a single image, asking for clarification on how size reduction is determined.
  • A participant points out that the event horizons are not perfectly spherical due to gravitational effects, asserting that they are not decreasing in size.
  • Further, a participant proposes that as two black holes approach each other, their event horizons might change shape and size, potentially shrinking at certain radial positions.
  • Another participant argues that event horizons do not actually get smaller, suggesting that any perceived size change is due to distortion from curved spacetime, and questions the validity of the size change claim based on visual representation.

Areas of Agreement / Disagreement

Participants express differing views on whether black hole event horizons can shrink in the presence of another black hole. There is no consensus, as some argue for potential size changes while others assert that event horizons remain constant in size.

Contextual Notes

Participants highlight the complexity of interpreting visual data and the influence of gravitational effects on the appearance of event horizons, indicating that assumptions about size changes may depend on specific conditions and measurements.

Algren
Messages
74
Reaction score
1
http://cdn4.sci-news.com/images/2016/02/image_3628-Gravitational-Waves.jpg
In the above image, i can see that the event horizon of each black hole has decreased in size. Does that mean that the event horizon can shrink in the presence of another black hole?
 
Last edited by a moderator:
Astronomy news on Phys.org
How are you concluding that they have decreased in size from a single image?
 
Borg said:
How are you concluding that they have decreased in size from a single image?
Its a screenshot of this video:
 
The event horizons are not perfectly spherical due to gravitational effects from each other but they're not decreasing in size.
 
Borg said:
The event horizons are not perfectly spherical due to gravitational effects from each other but they're not decreasing in size.
But as the two black holes come closer, don't their event horizons change shape and size, and perhaps shrink at some radial positions?
And if coming closer increases event horizon size(for all radial positions), wouldn't going away decrease the event horizon size?
 
The event horizons do not get smaller. Their images, distorted by the heavily curved spacetime, can appear smaller. I'm not even sure if that happens here. Would probably need some measurement of pixel diameters.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 0 ·
Replies
0
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 51 ·
2
Replies
51
Views
6K
  • · Replies 12 ·
Replies
12
Views
4K
  • · Replies 46 ·
2
Replies
46
Views
9K