If photons have no mass,why would black holes attract light?

Click For Summary

Discussion Overview

The discussion revolves around the question of why black holes attract light, given that photons are said to have no mass. Participants explore the implications of masslessness in relation to gravitational attraction, particularly in the context of black holes and the nature of light.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the relationship between mass and gravitational attraction, suggesting that if photons are massless, they should not be affected by gravity, leading to confusion about the nature of black holes.
  • Another participant asserts that mass is not necessary for attraction, indicating that the trajectory of light can be influenced by gravity regardless of mass, referencing principles from both classical mechanics and relativity.
  • A third participant emphasizes that gravitational force depends on mass, which raises questions about how black holes interact with massless particles like photons.
  • A later reply references a FAQ entry that addresses the question of massless photons and gravity, suggesting that this topic has been discussed previously and may have established explanations.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between mass and gravitational attraction, with some asserting that masslessness does not preclude gravitational influence, while others seem to question this understanding. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference concepts from relativity and classical mechanics, but the discussion does not resolve the underlying assumptions about the nature of gravity and light. There is a lack of consensus on how to reconcile the masslessness of photons with their interaction with black holes.

Murtuza Tipu
Messages
47
Reaction score
2
If photons have no mass, why would black holes attract light?
I was told that photons have no mass. However I thought that black holes are called "black" because no light can go escape the gravity force in their vicinity. I somehow think that, if light is just photons, then it should not be affected by gravity. Hence black holes could catch everything but light.

Do I miss something? Is light more than a bunch of photons? Or maybe black holes are not exactly what I think.
 
Physics news on Phys.org
Murtuza Tipu said:
If photons have no mass, why would black holes attract light?

Mass is not necessary to be attracted. The trajectory is independent from mass (both in classical mechanics and relativity).
 
What makes a black hole to attract anybody ? Gravitational force and it depends on mass
 
Murtuza Tipu said:
If photons have no mass, why would black holes attract light?
I was told that photons have no mass. However I thought that black holes are called "black" because no light can go escape the gravity force in their vicinity. I somehow think that, if light is just photons, then it should not be affected by gravity. Hence black holes could catch everything but light.

Do I miss something? Is light more than a bunch of photons? Or maybe black holes are not exactly what I think.

What you missed is reading our Relativity FAQ on this entry:

https://www.physicsforums.com/threads/why-are-massless-photons-affected-by-gravity.511173/

This question has been asked many times and it is sufficiently addressed at the simplest level in that entry.

Zz.
 
What ZapperZ said. This thread is closed.
 

Similar threads

High School A photon always travels in a black hole
  • · Replies 9 ·
Replies
9
Views
1K
Undergrad Can light be reflected in a black hole?
  • · Replies 22 ·
Replies
22
Views
2K
Undergrad Supermassive black hole, surface gravity and tidal forces
  • · Replies 62 ·
3
Replies
62
Views
8K
Undergrad Looking closely at the descent into a black hole
  • · Replies 51 ·
2
Replies
51
Views
958
Undergrad Can Gravity Escape a Black Hole?
  • · Replies 21 ·
Replies
21
Views
3K
High School Black hole electromagnetic spectrum
  • · Replies 4 ·
Replies
4
Views
2K
High School Theories about light and time near a black hole
  • · Replies 20 ·
Replies
20
Views
2K
High School Is there a white hole inside every black hole?
  • · Replies 22 ·
Replies
22
Views
1K
Undergrad How Does Mass Loss from Black Hole Mergers Affect Orbits?
  • · Replies 13 ·
Replies
13
Views
2K
Graduate Error in Landau-Lifshitz Vol 2, Fig. 20, page 310
  • · Replies 7 ·
Replies
7
Views
997