Summary and Transparencies for Class 6 - January 24, 2002

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Introduction: On Absolute Space and Time

"The universe is not twice given, with an earth at rest and earth in motion; but only once, with its relative motions alone determinable."

-- Mach, 1883

"This absolute time can be measured by comparison with no motion; it has therefore neither a practical nor a scientific value; and no one is justified in saying that he knows aught about it. It is an idle metaphysical conception."

-- Mach, 1883

"There is no absolute space … There is no absolute time."

-- Poincaré, 1902

Today's Class

We introduced the influence of Mach on Einstein's developement of the relativity theories. The quotes in the Introduction above were used in this discussion. We shall return to this in more detail when we discuss the General Theory of Relativity.

Once again, today's order of discussion was only loosely related to the order in the Supplementary Notes. We talked about materials contained in:

• Spacetime
  More Spacetime Diagrams and Some Discussion We haven't quite finished the material in this sub-section.
  The Significance of the Minus Sign Done
• Further Consequences of Einstein's "Explanation"
  Time Dilation Done
  Length Contraction Done