Electromagnetic stress energy tensor

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Discussion Overview

The discussion revolves around the electromagnetic stress-energy tensor and its potential effects on gravity, particularly whether electromagnetic fields can exhibit properties akin to antigravity. Participants explore theoretical implications in the context of the Reissner-Nordström and Kerr metrics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions if the negative components of the electromagnetic stress-energy tensor can reduce gravitational intensity, suggesting a possible analogy to dark energy.
  • Another participant notes that in the Reissner-Nordström metric, charge may create a form of antigravity near the curvature singularity, potentially affecting the event horizon's radius.
  • A subsequent post reiterates the idea of antigravity in the Reissner-Nordström metric, while providing mathematical expressions for the metric components and discussing the weak influence of electromagnetic fields compared to gravity.
  • There is mention of the Kerr metric exhibiting similar antigravity effects near curvature singularities.

Areas of Agreement / Disagreement

Participants express differing views on the implications of electromagnetic fields on gravity, with some proposing the existence of antigravity effects while others challenge the feasibility and observational support for such claims. The discussion remains unresolved.

Contextual Notes

Participants highlight the weak nature of electromagnetic interactions relative to gravitational forces, suggesting that assumptions about antigravity may lead to paradoxes within general relativity. There are also references to the lack of experimental evidence supporting these ideas.

relativityfan
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hi,

I would like to know if the contribution of some electromagnetic field through the electromagnetic stress energy tensor can decrease the intensity of gravity. it has negative components.

can it decrease pressure?

in such case, this would lead to some kind of relative antigravity like dark energy?

thank you for your reply!
 
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in the Reissner Nordstrom metric, the charge seems to generate some kind of antigravity near the curvature singularity and it decreases the radius of the event horizon. does that mean that electromagnetism generates there some kind of relative antigravity?
 
relativityfan said:
in the Reissner Nordstrom metric, the charge seems to generate some kind of antigravity near the curvature singularity and it decreases the radius of the event horizon. does that mean that electromagnetism generates there some kind of relative antigravity?

The contribution of electromagnetic field to the metric is positive in the Reissner Nordstrom metric as can be understood from the following perturbative terms appearing in the first and second components of the line-element:

[tex]g_{00}=1-2m/r+4\pi Ge^2/r^2c^4[/tex] and
[tex]g_{11}=1/g_{00}.[/tex]

The electromagnetic field always produces a really tiny curvature unisonant with the curvature generated by the existence of matter and gravitational field. Antigravity just states that if a gravitating body has a negative total charge, then all the charged particles with the same charge sign would escape from gravity. But this has not been ever observed experimentally and usually is perdicted to be wrong because as a result of the electromagnetic field being really weak compared to the gravitational force, such interation wouldn't be possible and would indeed lead to big paradoxes inside the GR; one being the fact that gravity is an attractive force. Google "Göde Scientific Research Foundation" to get the newest news on this issue.

AB
 
in the Kerr metric the same applies near the curvature singularity with some kind of antigravity
 

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