Recent content by Jim Lai

Hi everyone, I am a new member and would like to ask a naive simple (my guess) question. I am reading Weinberg’s Gravitation and Cosmology. On page 59, Eq. 2.12.10 therein reads $$ \begin{aligned} \left[\sigma_{\alpha \beta}\right]_{\gamma \delta}{}^{\varepsilon \zeta} &=\eta_{\alpha \gamma}...

My math sucked in high school so I chose not to do physics in college. Did Economics instead. I had kept reading popular books but felt deeply unsatisfied. The only good thing coming out of COVID is the abundance of online material on advanced physics supplied by prominent physicists. So I...