- #1
sderamus
- 19
- 0
In reviewing some basic GR (just to keep my old brain sharp), i was looking at the Einstein notation cinvention and was a bit confused. I see how you do the dot product of say:
ei.ej = δij
(i.e. 1 or 0)
But then the book I'm reading talks about ei.ej or ei.ej. Isn't that just the square of ei or ei? I thought the choice of index notation was irrelevant as it just goes over 1, 2, 3?
Or am I missing something basic? (first time in my life!)
If it is, why not just call it square?
Thanks!
Sterling
ei.ej = δij
(i.e. 1 or 0)
But then the book I'm reading talks about ei.ej or ei.ej. Isn't that just the square of ei or ei? I thought the choice of index notation was irrelevant as it just goes over 1, 2, 3?
Or am I missing something basic? (first time in my life!)
If it is, why not just call it square?
Thanks!
Sterling