Integration of energy-momentum pseudotensor for Kerr BH

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Discussion Overview

The discussion revolves around the integration of the energy-momentum pseudotensor for Kerr black holes, comparing it to previous calculations done for Schwarzschild black holes. Participants explore the feasibility of obtaining mass and angular momentum through similar methods and the applicability of the Landau–Lifshitz pseudotensor.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes having calculated the integral of the Einstein energy-momentum pseudotensor for a Schwarzschild black hole, yielding a value corresponding to the mass of the black hole, and questions if a similar approach can be applied to Kerr black holes.
  • Another participant expresses skepticism about the straightforwardness of the Schwarzschild calculation and requests clarification on the method used.
  • A participant references Dirac's work on the Einstein pseudotensor and mentions excitement over finding that black hole energy exists outside the Schwarzschild surface.
  • Another participant challenges the claim regarding black hole energy, emphasizing the need for caution when interpreting pseudotensors and stating that the Schwarzschild black hole is a vacuum with no stress-energy present.
  • They also mention that the mass of the black hole is a global property of spacetime and cannot be localized, suggesting that invariant mass integrals exist but do not involve pseudotensors.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of energy associated with black holes and the validity of using pseudotensors for such calculations. There is no consensus on the claims made regarding the energy-momentum pseudotensor and its implications for Kerr black holes.

Contextual Notes

Participants reference specific equations and concepts from general relativity, but some details are missing or not fully explained, leading to potential misunderstandings about the application of pseudotensors and the nature of black hole mass.

anuttarasammyak
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TL;DR
Integration of energy-momentum pseudotensor for Kerr BH
Once, I calculated the integral of the Einstein energy–momentum pseudotensor for a Schwarzschild black hole in the region outside the Schwarzschild surface and obtained the value m, corresponding to the mass of the black hole.

Performing the same calculation for a Kerr black hole would be quite laborious. May I expect to obtain the mass m and the angular momentum M in a similar manner? Is it also possible to obtain the same results using the Landau–Lifshitz pseudotensor?
 
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anuttarasammyak said:
Once, I calculated the integral of the Einstein energy–momentum pseudotensor for a Schwarzschild black hole in the region outside the Schwarzschild surface and obtained the value m, corresponding to the mass of the black hole.
How? This is not quite as straightforward as you seem to think.

anuttarasammyak said:
Performing the same calculation for a Kerr black hole would be quite laborious. May I expect to obtain the mass m and the angular momentum M in a similar manner?
I have no idea unless you explain how you did the Schwarzschild calculation.

anuttarasammyak said:
Is it also possible to obtain the same results using the Landau–Lifshitz pseudotensor?
Same answer as above.
 
From "general theory of relativity" by Dirac, as for Einstein pseudotensor,
(32.3)
where ##\mathcal{L}=\sqrt{}\ L## with
(26.3)
, we got the formula for Schwartzshild coordinates and metric given by
(18.6)
and integrated in volume outside the Schwartzshild surface, r > 2m as
(31.4)

I did it with a friend of mine online before websites become familiar. We were excited to see that BH has its energy all outside the Schwartzshild surface.

[EDIT] I deleted the equation images by the suggestion post #4.
 
Last edited:
anuttarasammyak said:
From "general theory of relativity" by Dirac, as for Einstein pseudotensor,
View attachment 367131
where ##\mathcal{L}=\sqrt{}\ L## with
View attachment 367132
, we got the formula for Schwartzshild coordinates and matrix given byView attachment 367134
and integrated in volume outside the Schwartzshild surface, r > 2m as
View attachment 367135
I did it with a friend of mine online before websites become familiar. We were excited to see that BH has its energy all outside the Schwartzshild surface.
Equations in images are not permitted here. Please use the PF LaTeX feature.
 
anuttarasammyak said:
We were excited to see that BH has its energy all outside the Schwartzshild surface.
This is not a correct claim. You need to be very, very careful interpreting anything involving pseudotensors. The Schwarzschild BH is vacuum; it has no stress-energy anywhere. The "mass" ##M## of the hole is a global, geometric property of the spacetime; it can't be located in any particular place or region.

There are invariant mass integrals that can be done for Schwarzschild spacetime (ADM mass, Bondi mass, Komar mass--though the latter involves more technicalities). But none of them involve pseudotensors.
 

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