35 research outputs found
Some remarks on the notions of general covariance and background independence
In the first part of this paper I review some of the difficulties that seem
to obstruct generally valid definitions of "general covariance" and/or
"background independence" The second and more historical part deals with a
rather strange argument that Einstein put forward in his 1913 "Entwurf paper"
with M. Grossmann to discredit scalar theories of gravity in order to promote
general covariance.Comment: 26 pages, 3 figures. Contribution to ``An assessment of current
paradigms in the physics of fundamental interactions'', edited by I.O.
Stamatescu (Springer Verlag, to appear
Mathematical methods of electromagnetic theory
This text provides a mathematically precise but intuitive introduction to classical electromagnetic theory and wave propagation, with a brief introduction to special relativity. While written in a distinctive, modern style, Friedrichs manages to convey the physical intuition and 19th century basis of the equations, with an emphasis on conservation laws. Particularly striking features of the book include: (a) a mathematically rigorous derivation of the interaction of electromagnetic waves with matter, (b) a straightforward explanation of how to use variational principles to solve problems in e