That's a crucial point of GR !(adsbygoogle = window.adsbygoogle || []).push({});

And I have always problems with that.

Back to the basics, with your help.

Thanks

Michel

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Why should the covariant derivative of the metric tensor be 0 ?

**Physics Forums | Science Articles, Homework Help, Discussion**