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13
Quantum Mechanics
13.1 INTRODUCTION
What is usually called modern physics is based on two theories: relativity, which we
have just nished discussing, and quantum mechanics (also called quantum theory).
While some of the ideas of relativity, such as time dilation and length contraction,
at rst seemed rather strange, we saw that they followed logically from the two pos-
tulates of relativity. We will see below that the ideas of quantum mechanics are also
strange. Most physicists would agree that they are much stranger than relativity. In
fact, we will see that there are no satisfactory explanations. To quote two Nobel Prize
laureates, Mur ...