Introduction

• Exploring what quantum physics really means
• The prevailing interpretation of modern quantum physics
• Observation and objective reality
• A few counterintuitive thought experiments

The quantum physics we have described so far has proven extremely successful at predicting all sorts of usual—and unusual—effects observed at the sub-atomic level. The old laws of classical physics, which work so well for objects of macroscopic size, utterly fail to predict these observations.

But classical physics never required us to violate our intuition as much as quantum physics does. Having lost the idea of definite particle locations, the distinction between waves and particles, and determinism, it is natural for us to ask: what do the claims of quantum physics really mean?

We will take our first few steps toward answering this question. The goal, as always, is a deeper understanding of how the universe works, or why it must be the way it appears to be. Perhaps we are only trying to get a little more comfortable with this weird view of the world at the subatomic level. Since quantum physics is relatively young, it is no surprise that there is still a lot of controversy about how to interpret it correctly. We’ll start by discussing one of the earliest attempts at a coherent interpretation, the one which has gained the most widespread acceptance among physicists and physics teachers today.