$$ {\eta}^{\mu\nu} = {\Lambda}^{\mu}_{\sigma} {\Lambda}^{\nu}_{\gamma}{\eta}^{\sigma\gamma} $$
This expression. I am trying to write it without the indices, but don't know where they go on the lambda tensor
$$ {\Lambda}^{i}_{j} $$
When indices are written on top of one another I am confused wich is the inner index and which is the lower one when we lower the upper index.
So invariance refers to specific quantities physical or mathematical. While covariance refers to the relationship between those quantities, the equations?
What is the difference between these two concepts? An equation is said to be "invariant" under some operation if the form of the equation doesn't change. However, isn't that exactly what "covariance" in physical laws means—that the form of the laws remains unchanged when applying an operation to...