Derive Reissner Nordstrom Eq. (8) Explained

  • Thread starter Thread starter darida
  • Start date Start date
  • Tags Tags
    Metric
darida
Messages
35
Reaction score
1
I want to derive Reissner Nordstrom solution using this paper as a guide: http://gmammado.mysite.syr.edu/notes/RN_Metric.pdf, but I get confused by the Eq. (8). Why the Enstein's equation can be rewritten in that form and what is the physical meaning of the Eq. (8)?
 
Physics news on Phys.org
Contract both sides of (3) with ##g^{\mu\nu}## and you will get a condition for ##R##
 
  • Like
Likes darida
Ah thank you, that's so simple >_<
 
The trace of the energy-momentum tensor of a classical massless field vanishes because of symmetry under dilations. Now use the hint in #2.
 
  • Like
Likes darida
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
The Poynting vector is a definition, that is supposed to represent the energy flow at each point. Unfortunately, the only observable effect caused by the Poynting vector is through the energy variation in a volume subject to an energy flux through its surface, that is, the Poynting theorem. As a curl could be added to the Poynting vector without changing the Poynting theorem, it can not be decided by EM only that this should be the actual flow of energy at each point. Feynman, commenting...
Back
Top