# Homework Help: Quesion about amper and relativty

1. Aug 5, 2009

### menniandscience

hello, this is from article and i can't understand it,

"One can see an analogous sort of indeterminateness at the basis of A. Einstein's (1952, p. 37) complaint against pre-relativistic mechanics and electrodynamics. His criticism was that they lead "to asymmetries which do not appear to be inherent in the phenomena." Whether one assigns an absolute velocity of zero to a conductor and a non-zero velocity to a magnet, or vice versa, the measurable result (current) is the same. Hence, the absolute velocity is indeterminate: "The phenomena . . . possess no properties corresponding to the idea of absolute rest," as Einstein put it. Interpreted a la Glymour, the point is not the naive one that absolute velocity is not measurable-that would be alright-but that it cannot even be computed from measured quantities via any seriously proposed (let alone well-tested) hypotheses.

why does einstein says there is no symmetry? why can't we mesure current according to the text? if so, what is ampermeter??

thank you