What is the Wavelength of Hawking Radiation?

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Discussion Overview

The discussion revolves around the properties and implications of Hawking radiation, particularly in the context of extremely small black holes and their associated temperatures and wavelengths. Participants explore theoretical aspects, including the Kerr Temperature, Schwarzschild radius, and the relationship between black hole mass and radiation characteristics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants discuss the Kerr Temperature and its relation to the energy spectrum of Kerr black holes, suggesting a connection to Thermodynamic Quantum Gravitation.
  • One participant questions whether an extremely small black hole, with a Schwarzschild radius smaller than the Planck length, could radiate light with more mass or momentum than itself.
  • Another participant provides mathematical expressions for the Schwarzschild radius and temperature, raising concerns about conservation of energy and momentum if such small black holes could emit high-energy radiation.
  • There is a proposal that a black hole smaller than the Schwarzschild-Planck radius would not radiate in a conventional sense, and its radiation characteristics would differ significantly.
  • Some participants argue that conservation laws might not be violated if a black hole can absorb energy from the vacuum, suggesting a theoretical framework where energy absorption could balance radiation emission.
  • One participant mentions the need for a complete theory of quantum gravity to accurately describe Hawking radiation for very small black holes, indicating limitations in current models.
  • A participant expresses a desire to know the wavelength of Hawking radiation for a project, indicating a practical interest in the topic.

Areas of Agreement / Disagreement

Participants express differing views on the implications of black hole size on radiation characteristics, particularly regarding conservation laws and the validity of existing theories. There is no consensus on the wavelength of Hawking radiation or the behavior of black holes smaller than the Planck length.

Contextual Notes

The discussion highlights limitations in current theoretical frameworks, particularly in relation to very small black holes and the assumptions underlying Hawking radiation derivations. The implications of energy absorption from the vacuum and its effects on conservation laws remain unresolved.

Who May Find This Useful

This discussion may be of interest to those studying black hole thermodynamics, quantum gravity, and the theoretical aspects of Hawking radiation, as well as individuals seeking to understand the implications of black hole size on radiation properties.

Orion1
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One of the real important aspects of Hawking Radiation is the Kerr Temperature.

Note that the Kerr Temperature is responsible for the Kerr Particle Energy Spectrum and represents the genesis of Thermodynamic Quantum Gravitation.

Thermodynamic Quantum Gravitation is the combination of Thermodynamics and Quantum Gravitation:

A Kerr Black Hole is a rotating Black Hole.

[tex]T_k = \frac{\hbar c^3}{K_o G M}[/tex]

Ko = Boltzmann's Thermal Constant
 
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Since you brought it up, I have this rather silly question about Hawking radiation:

Let's say that I have an extremely small black hole -- i.e. the Schwartzschild radius is smaller than the Planck length.

Wouldn't a black hole like this have a tendency to radiate light that had more mass/momentum than the black hole does?
 


Schwarzschild radius:
[tex]r_s = \frac{2 G M}{c^2}[/tex]

Planck Length:
[tex]r_p = \sqrt{ \frac{ \hbar G}{c^3}}[/tex]

Schwarzschild Temperature:
[tex]T_s = \frac{ \hbar c^3}{4 K_o G M}[/tex]

[tex]r_s = r_p[/tex]

[tex]\frac{2 G M}{c^2} = \sqrt { \frac{ \hbar G}{c^3}}[/tex]

Schwarzschild-Planck Mass:
[tex]M_s = \frac{1}{2} \sqrt { \frac{ \hbar c}{G}}[/tex]

Integral:
[tex]M_s = \frac{1}{2} \sqrt { \frac{ \hbar c}{G}} = \frac{ \hbar c^3}{4 K_o G T_s}[/tex]

Schwarzschild-Planck Temperature:
[tex]T_s = \frac {1}{2K_o} \sqrt { \frac{\hbar c^5}{G}}}[/tex]

[tex]T_s = 7.084E+31 K[/tex]
T_s = 7.084*10^31 Kelvin
[/color]

Schwartzschild radius is smaller than the Planck length.

Wouldn't a black hole like this have a tendency to radiate light that had more mass/momentum than the black hole does?

if the black hole were smaller than that, then would it be able to radiate?

[tex]r_s \ll r_p[/tex]

[tex]\Delta = \frac {\hbar c}{ \lambda K_o T_s} = \frac{2}{ \lambda} \sqrt { \frac {\hbar G}{c^3}}[/tex]

[tex]\Delta = \frac{2}{ \lambda} \sqrt { \frac {\hbar G}{c^3}}[/tex]

[tex]T_q = \frac {\hbar c^3}{4 K_o G M_s ( e^\Delta - 1)}[/tex]

[tex]I(\lambda) = \frac { 2 \pi h c^2}{ \lambda^5 (e^\Delta - 1)}[/tex]

[tex]I_q = \sigma T_q^4[/tex]

[/color]

The Schwarzschild-Planck Radius is Mass dependent.

As a Thermodynamic Schwarzschild-Planck Black Hole radius falls below the Planck Radius [tex]r_s \ll r_p[/tex], it becomes a Thermodynamic Quantum-Schwarzschild Black Hole, the resulting radiation diminishes instead of increasing.

The resulting radiation flux becomes less energetic than the mass equivalency.

A Thermodynamic Schwarzschild-Planck Black Hole would evaporate instantly however a Thermodynamic Quantum-Schwarzschild Black Hole diminishes more gradually, however still relatively instantaneous. The relative flux intensity also diminishes.

A Quantum-Schwarzschild Black Hole Thermodynamic Temperature is quantumized below the Planck Radius.

[/color]
 
Last edited:
Originally posted by Orion1
A Schwarzschild-Planck Black Hole would evaporate instantly.

Right, but if the black hole were smaller than that, then would it be able to radiate? Conservation of energy/mass would be grossly violated if the black hole could produce radiation with more energy than it's equivalent mass. Similarly, there might be problems with conservation of linear momentum.
 
http://www.th.physik.uni-frankfurt.de/~lxd/English/bhs_e.html
http://relativity.livingreviews.org/Articles/lrr-2001-6/node7.html

"Imaginary Time" (which theoretically exists at right angles to ordinary time) may hold the key to this one. However, we’re yet to probe THAT dimension…
 
Last edited by a moderator:
Conservation of energy/mass would be grossly violated if the black hole could produce radiation with more energy than it's equivalent mass

Not if the black hole can absorb as much energy from the vacuum as it radiates and there is theoretically 10^120 Joules per cubic metre in the vacuum.
 
Planck Probability...

Conservation of energy/mass would be grossly violated if the black hole could produce radiation with more energy than it's equivalent mass

Not if the black hole can absorb as much energy from the vacuum as it radiates and there is theoretically 10^120 Joules per cubic metre in the vacuum.

What if a Schwarzschild-Planck Black Hole is capable of absorbing more radiation than its Schwarzschild-Planck Temperature vacuum, does this also violate Conservation of energy/mass?

I presume that a Schwarzschild-Planck Black Hole which is capable of absorbing more radiation than its Schwarzschild-Planck Temperature vacuum would momentarily increase in mass, then still evaporate instantly.

To my understanding, a 'perfect radiation absorber' is not possible, but then again it was once thought that black holes were a 'zero radiation emitter'.

Is there an equation that exists that determines how much radiation a Schwarzschild-Planck Black Hole is capable of absorbing?

According to my integrations above, the amount of Schwarzschild-Planck Black Hole radiation flux produced below the Planck Radius [tex]r_s \ll r_p[/tex] is no longer determined by mass thermodynamics, but by probability and radiation wavelength similar to a blackbody radiator, given here: [tex]P = (e^\Delta - 1)[/tex].

Thereby, when Schwarzschild-Planck Black Hole falls below Planck radius [tex]r_s \ll r_p[/tex], the radiation flux probabilisticly diminishes, resulting in a radiation flux that no longer violates Conservation of energy/momemtum. However note that the evaporation is still relatively instantaneous, as such equations are described in 'slow motion'.
 
NateTG said:
Let's say that I have an extremely small black hole -- i.e. the Schwartzschild radius is smaller than the Planck length.

In that case, the derivation of Hawking radiation is no longer valid. You'd need a fully theory of quantum gravity, whereas Hawking radiation is derived by formulating quantum field theory on top of a fixed classical spacetime.
 
Wavelength

I am Doing a project on Hawking Radiation and I am wondering if anyone actually Knows the wavelength of it?? It would be great if someone could email me cos I don't always have time to do much more than check my emails

--
a.random.persona@gmail.com
--
Thanks
 

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