HPS 0410 Einstein for Everyone Fall 2008

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Assignment 5: Origins of Special Relativity

For submission Mon. Sep. 22, Tues. Sep. 23, Wed. Sep. 24

Read the introduction and first two sections of Einstein's paper "On the electrodynamics of moving bodies." Read it slowly and reverently. This text is to modern physics what Genesis is to modern Judeo-Christianity and the Declaration of Independence is to US history.

1. Compare what is moving with respect to what in the magnet and conductor thought experiment in the account Einstein' in his paper and in the account in the chapter, Magnet and Conductor. How do the two accounts differ?

2. What is the "definition of simultaneity" that Einstein describes in the first section of his paper? That is, what must be stipulated by definition according to Einstein if we are to be able to compare the timing of events at a point A and a point B of space,

For discussion in the recitation.

A. In the introduction, what is established by the magnet and conductor thought experiment?

B. In the introduction, how do ether current experiments enter the discussion?

C. In the introduction, what is "apparently irreconcilable" and why is it so? How is Einstein suggesting that he will solve the problem?

D. In Section 2, how does Einstein establish that observers in relative motion may disagree on the lengths of rods and the synchrony of clocks?

E. If the synchrony of different clocks is set by a definition, presumably freely chosen, then it would seem that any velocities measured by them are also a matter of freely chosen definition. So how can Einstein at the end of Section 1 say that the constancy of the speed of light is a universal constant "in agreement with experience"?