Back to Quantum Mechanics

**Completeness Question**

- The predictions of Quantum Mechanics are probabilities
- Versus the deterministic predictions of Classical Physics

- The question
- Does the probabilistic nature of the predictions result from not knowing all the variables or from real chance in nature?

- Einstein argued that Quantum Mechanics was incomplete:
- “I, at any rate, am convinced that He does not play dice.”

**Measurement Question**

**Measurement Question**

- Three postulates of Quantum Mechanics explicitly use the undefined term
*measurement*- Time Evolution, Prediction, Collapse
- (The postulates of Classical Physics do not use the term.)

- What constitutes a
*measurement*and when precisely does a*measurement*take place?- Does
*measurement*require a conscious observer? - Does
*measurement*involve the interaction between the subatomic world and the world of everyday objects?

- Does