Can it escape the event horizon if the wavelength is long enough?

Click For Summary

Discussion Overview

The discussion centers on whether electromagnetic radiation can escape from the event horizon of a black hole if the wavelength is sufficiently long. It explores theoretical scenarios involving charged black holes and the implications of electromagnetic forces in this context.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions if electromagnetic radiation can escape a black hole's event horizon, particularly considering long wavelengths and charged black holes.
  • Another participant asserts that electromagnetic radiation cannot escape, emphasizing that electric charge is mediated by virtual photons, which can theoretically travel faster than light.
  • A different viewpoint suggests that classical electromagnetism should be applied, arguing that static electric fields from charged matter affect external observers without requiring photons to escape the black hole.
  • Concerns are raised about the concept of photons with long wavelengths fitting inside the event horizon, with a claim that classical electromagnetic waves would simply bypass the black hole.
  • Participants discuss a hypothetical scenario involving two orbiting charged black holes, questioning whether they could radiate electromagnetic energy, with one suggesting that any radiation would originate from outside the event horizons.
  • Another participant introduces the idea that the probability of absorption of particles by a black hole depends on various parameters, not solely on the energy of the particle.

Areas of Agreement / Disagreement

Participants express differing views on the ability of electromagnetic radiation to escape a black hole, with no consensus reached on the implications of long wavelengths or the role of electric charge.

Contextual Notes

The discussion includes references to classical electromagnetism and virtual photons, highlighting the complexity of the interactions at play and the lack of definitive solutions for the scenarios proposed.

Puffer Fish
Messages
8
Reaction score
0
TL;DR
how very long wavelengths would interact with a black hole
Can electromagnetic radiation escape from the event horizon of a Black Hole if the wavelength is long enough?

What if a Black Hole contains electric charge, hypothetically supposing we dumped a large number of protons into it? Electric charge is mediated by the electromagnetic force. So the outside would not be able to feel any electric charge unless photons were able to permeate the boundary. (and we can say that the photons mediating static charges have extremely long wavelengths)

How can a photon with a wavelength longer than the diameter of the event horizon fit inside it?Some will claim "no energy can escape from a black hole", but here's one more thought experiment scenario to consider:
What if two black holes are circling each other very fast in a very tight orbit, one is positively charged and the other is negatively charged? You do not think that is going to be able to radiate electromagnetic energy? (it seems obvious to me it would. Hope that's not a false equivalency straw man though)
 
Physics news on Phys.org
Puffer Fish said:
Can electromagnetic radiation escape from the event horizon of a Black Hole if the wavelength is long enough?

No.

Puffer Fish said:
Electric charge is mediated by the electromagnetic force. So the outside would not be able to feel any electric charge unless photons were able to permeate the boundary.

Incorrect. If you are viewing the EM force as mediated by photons, they are virtual photons, which can, heuristically speaking, travel faster than light and so can get out of the hole.

However, General Relativity is a classical theory, not a quantum theory, so classical EM is really what you should be using in this scenario. And in classical EM, the static electric field of a charged black hole ultimately comes from charged matter in the past light cone of the observer who is measuring the field. In other words, the static electric field you feel if you are outside a charged black hole comes from whatever charged matter originally fell into the hole and gave it its charge. When that charged matter falls in, it leaves behind its static field, which continues to affect things outside.

Puffer Fish said:
(and we can say that the photons mediating static charges have extremely long wavelengths)

No, we can't. I have no idea where you are getting that from. In any case, as noted above, GR is a classical theory, not a quantum theory, so the correct EM theory to use here is classical EM, in which there are no "photons". If you want to discuss photons, you should open a new thread in the quantum physics forum.

Puffer Fish said:
How can a photon with a wavelength longer than the diameter of the event horizon fit inside it?

Again, in classical EM, there are no "photons". A classical EM wave with a wavelength longer than the size of a black hole will simply skip over the hole and won't go inside.

Puffer Fish said:
What if two black holes are circling each other very fast in a very tight orbit, one is positively charged and the other is negatively charged? You do not think that is going to be able to radiate electromagnetic energy?

If it does (it seems like it would, but AFAIK there is no known exact solution for this case), the radiation would be coming from outside the holes' horizons, generated by the non-static EM fields outside the holes' horizons; it would not be escaping from either hole.
 
  • Like
Likes   Reactions: Demystifier and PeroK
Puffer Fish said:
Summary:: how very long wavelengths would interact with a black hole

Can electromagnetic radiation escape from the event horizon of a Black Hole if the wavelength is long enough?
no
What if a Black Hole contains electric charge, hypothetically supposing we dumped a large number of protons into it? Electric charge is mediated by the electromagnetic force. So the outside would not be able to feel any electric charge unless photons were able to permeate the boundary. (and we can say that the photons mediating static charges have extremely long wavelengths)
But the electromagnetic force is mediated by virtual photons, not actual photons. So no actual photons need to escape the event horizon.
Some will claim "no energy can escape from a black hole", but here's one more thought experiment scenario to consider:
What if two black holes are circling each other very fast in a very tight orbit, one is positively charged and the other is negatively charged? You do not think that is going to be able to radiate electromagnetic energy? (it seems obvious to me it would. Hope that's not a false equivalency straw man though)
Any electromagnetic energy produced would come at the expense of the orbital energy of the Black holes involved, causing them to spiral in on each other. ( the gravitational waves first detected were produced by such a process; Orbiting black holes emit gravitational waves, the energy of which is extracted from the orbital energy of the pair. They spiral in towards each other, and the faster orbit increases the wave ouput...)
 
  • Like
Likes   Reactions: Demystifier and PeroK
I think that something in a black hole cannot escape. But the scattering question of a particle with a black hole (it is the subject of the summary) is interesting. the probability of absorption doex not only depend on the energy of the particle. It also depends on the "surface" of the black hole and several other parameters.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 51 ·
2
Replies
51
Views
6K
  • · Replies 46 ·
2
Replies
46
Views
9K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 73 ·
3
Replies
73
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 14 ·
Replies
14
Views
4K