Matter & Interactions I, Week 4

This week we formally wrapped our coverage (I hate that word) of special relativity. My goal never has been for students to do complicated numerical problems. Instead, I wanted them to understand the foundations of special relativity with an emphasis on the invariance of light’s speed, the loss of absolute simultaneity, and loss of absolute […]

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Matter & Interactions I, Week 3

This week, we encountered what, in my opinion, is the most fundamental aspect of special relativity: the loss of absolute simultaneity. The Michelson-Morley experiment established that light’s speed must be invariant. An immediate consequenc of this is that two events that are simultaneous in one inertial frame cannot be simultaneous in any other frame. Last […]

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Matter & Interactions I, Week 2

This week we began readings from chapter 36 (24MB) of Arnold Arons’ 1965 calculus-based textbook Development of Concepts of Physics (rare, but occasionally found on the used market…I have two copies and I hope to get Dover to reissue the book in paperback). This is the chapter on special relativity, and in my opinion forms the best foundation for relativity […]

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Building Up to Simultaneity (Activity)

Here’s a classroom activity intended to demonstrate the issue of simultaneity in measuring a stick’s length. Students need a calibrated metre stick (I’m trying to get into the habit of spelling it that way), another stick approximately 1/3 m long although the precise length is unimportant, two coins of the same denomination or two small pea-size balls […]

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