Recitation 3: Origins of Special Relativity

Here is Einstein's "On the Electrodynamics of Moving Bodies."

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

B. 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"?

C. What role did the Fresnel ether drag hypothesis play in the 19th century understanding of experiments aimed at showing the motion of the earth through the ether?

D.The Michelson-Morley experiment failed to reveal the motion of the earth through the ether. How did H. A. Lorentz explain this failure? How did Einstein explain it?

Review Exercises on E = mc²

We have been unable to schedule recitation discussion directly on E = mc². Here are some review and discussion questions you may find useful in preparation for the next test.