diff --git a/_posts/2025-01-06-einstein-sums.md b/_posts/2025-01-06-einstein-sums.md index fb1795b..e865631 100644 --- a/_posts/2025-01-06-einstein-sums.md +++ b/_posts/2025-01-06-einstein-sums.md @@ -83,7 +83,7 @@ The final trick is that this insertion of the metric in the middle of tensor con \\[\delta^\mu \delta_\nu = \delta_\mu \eta_{\mu\nu} \delta_\nu \\] -Now I've called these things hacks and tricks but they also connect to much deeper mathematical concepts such as [covariance and contravariance](https://en.wikipedia.org/wiki/Covariance_and_contravariance_of_vectors). This seems like it's usually the case with nice notation to be honest. It makes me things of the relationship between the derivative operator $\tfrac{d}{dt}$ and and the infinitesimal $dt$. +Now I've called these things hacks and tricks but they also connect to much deeper mathematical concepts such as [covariance and contravariance](https://en.wikipedia.org/wiki/Covariance_and_contravariance_of_vectors). This seems like it's usually the case with nice notation. It makes me think things like the relationship between the derivative operator $\tfrac{d}{dt}$ and and the infinitesimal $dt$.