Recent content by direct99

  1. D

    Physics Research in Physics: Combining Programming & Publishing

    I am just using my friend's account to ask a question and I have a MSc degree in physics its a four year course, three for undergraduate course and one for Masters course.
  2. D

    Physics Research in Physics: Combining Programming & Publishing

    I am doing research on my own and I have masters degree in physics.
  3. D

    Physics Research in Physics: Combining Programming & Publishing

    I am a physics graduate and I have just spent two years researching about problems like dark energy and dark matter and didn't get anywhere, did not even manage to write a single research paper. I like writing and publishing research papers as many as I can because they give me the feeling of a...
  4. D

    General Relativity: Contracting Indices

    so are you saying that $$ -g_{,\rho }^{\mu \rho }+g_{,\rho }^{\rho \nu }=0 $$ should be something like $$ -g_{,\sigma }^{\mu \sigma }+g_{,\rho }^{\rho \nu }=0 $$ If so does this mean that its equivalent to $$ g_{,\nu }^{[\mu \nu ]}=0 $$
  5. D

    General Relativity: Contracting Indices

    How to get equation (2) from $$ \frac{1}{2} g_{}^{\mu \rho } \Gamma _{a\rho }^a-\frac{1}{2} g_{}^{\rho \nu } \Gamma _{a\rho }^a+\frac{1}{2} g_{}^{\mu \rho } \Gamma _{\rho a}^a-\frac{1}{2} g_{}^{\rho \nu } \Gamma _{\rho a}^a+g_{}^{a\nu } \Gamma _{a\rho }^{\rho }-g_{}^{a\rho } \Gamma...
  6. D

    General Relativity: Contracting Indices

    Well, when contracting with respect to μ and ρ I get: $$ -\frac{1}{2} g^{\rho \nu } {\Gamma} _{a\rho}^{a}-\frac{1}{2} g^{\rho \nu} \Gamma _{\rho a}^{a}+g^{a\nu} \Gamma _{a\rho}^{\rho}+g^{\rho a} \Gamma _{\rho a}^{\nu}+g_{,\rho}^{\rho\nu}=0 $$ and when contracting with respect to nu and ρ I...
  7. D

    General Relativity: Contracting Indices

    Hello, I was reading a book about general relativity and I came across these two equations $$ \begin{align} \mathrm{g}^{\mu\nu}_{,\rho}+ \mathrm{g}^{\sigma\nu}{\Gamma}^{\mu}_{\sigma\rho}+ \mathrm{g}^{\mu\sigma}{\Gamma}^{\nu}_{\rho\sigma} -\frac{1}{2}(...
  8. D

    Space Translation: Sidney Coleman's Lectures Problem

    Hi, In Sidney Coleman's Lectures he talked about space translations such that but when I expanded the exponentials and and used the commutation relation of p and x, I got ρ(x+a) instead of ρ(x-a) Does anyone see where I may of went wrong?
  9. D

    Calculating Average Power for Raising a Roller Coaster Car

    Hello I have a problem with this exam question does anyone now the solution. Homework Statement A roller coaster car has a mass of 800 kg. The gravitational field strength is 10 N/kg. It takes 20 s for the car to reach K from the start. What is the average power required to raise...
Back
Top