Hey!
In cosmology the notion of a photon fluid is often used, i.e. a perfect fluid with the equation of state P=\frac{\rho}{3} and the stress-energy- momentum tensor of a perfect fluid. On the other hand, a photon fluid is just an electromagnetic field with the well- known definition for its...
In the course of my research I came across this PDE
\frac{\partial{a_0}}{\partial{x}}\frac{\partial{a_1}}{\partial{y}}-\frac{\partial{a_0}}{\partial{y}}\frac{\partial{a_1}}{\partial{x}}=0.
with both functions depending on x and y.
I am quite sure I have seen equations of this form before but...
Hey!
I stumbled across this problem while reading Wald's "General Relativity", but it belongs to Electrodynamics. In problem 3 of chapter 6 one has to find the general form of a static, spherically symmetric Maxwell tensor, which is clearly F_{ab}=A(r)(dt)_a \wedge (dr)_b+B(r)r(d\theta)_a...
Hey,
For a problem I am working on I need to know if the energy-momentum tensor of the Reissner- Nordstrom metric obeys the weak energy condition. Since I need the result for the following calculations, I just want to be sure that it is correct. Does anyone of you know the correct answer and...