Why Did Einstein Criticize Absolute Velocity in Pre-Relativistic Mechanics?

[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 . . . possesses 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

 

[NateD]

for your help.Einstein was criticizing the idea that pre-relativistic mechanics and electrodynamics assumed there was an absolute velocity, i.e. a standard velocity to which all other velocities were relative. He argued that assigning one set of objects an absolute velocity and another non-zero velocity to a magnet (or vice versa) would not result in any difference in the measurable current. This means that absolute velocity is indeterminate - it cannot be computed from measurable quantities. An ammeter is a device used to measure electric current, so it can measure the current regardless of the absolute velocity assigned.