When one starts learning about physics, vectors are presented as mathematical quantities in space which have a direction and a magnitude. This geometric point of view has encoded in it the idea that under a change of basis the components of the vector must change contravariantly such that the magnitude and direction remain constant. This restricts what physical ideas may be the components of a vector (something much better explained in Feynman's Lectures), so that three arbitrary functions de not form an honest vector →A=Axˆx+Ayˆy+Azˆz in some basis. So, in relativity a vector is defined "geometrically" as directional derivative operators on functions on the manifold M and this implies, if Aμ are the components of a vector in the coordinate system xμ, then the components of the vector in the coordinate system xμ′ are Aμ′=∂xμ′∂xμAμ
My problem is the fact that too many people use the coordinates xμ as an example of a vector, when, on an arbitrary transformation, xμ′≠∂xμ′∂xμxμ
No comments:
Post a Comment