PHY132S Relativity - Class 3 - Monday March 30 2009


Typically I do not comment on the introductory first slide that I show before the class begins. Today I made an exception.

Michelson's quote from 1899 proclaiming the end of science was a popular view of the day. But there were a couple of small clouds on the horizon. One cloud led to the Special Theory of Relativity of 1905, which was a huge revolution in the way physics thinks about space, time, etc. It is particularly ironic that one aspect of that cloud was Michelson's own experiment with Morley in 1887.

Recently some people, especially John Horgan in his book The End of Science (1996), have been making similar claims about how the enterprise of science is complete. In our final class of the term I will discuss a cloud that may make Horgan's claim as wrong as Michelson's was in 1899.

Reading Assignments

This week: SCN§B, §37.7, SCN §C, §37.9, §37.10

Next week: SCN §D, Equivalence Principle sub-section of §13,3

Suggested Problems

This week: Chapter 37: 57, 63, 75. SCN 2, 3, 4 (Parts 1 and 2 only), 5

First edition: Chapter 36: 57, 63, 75

Next week: none.

Today's Class

We began by picking up a loose end: the Relativistic Doppler Effect which the text discussed without justification in §20.7.

Then we showed that the phenomenon of time dilation necessarily leads to the relativistic length contraction. We showed that the existence of length contraction necessarily leads to the fact that two events may be simultaneous for some observer but not simultaneous for another observer.

We then discussed §C of the SCN. This included:

The Side Screen Slides
Today's Journal