**ABOUT THIS QUANTUM PHYSICS ENCYCLOPEDIA**

I’m writing this encyclopedia of quantum physics for people who are not yet experts, including physics students and laypeople. I like to provide examples and to stay clear of equations. That said, I have included some simple but important equations at the end of some of the articles. Feel free to skip them!

The downside of this approach is that experts may feel that the definitions are not sufficiently precise since they omit the technical terminology and the math that lend precision. Yep, that’s a downside. I’m shooting for giving you sound but general conceptual understandings. It’s best to look elsewhere for the refinements possible with more technical terminology and equations.

I’m not a physicist. I’m someone who is very interested in quantum physics and want to share what I’ve learned with others.

**Quantum physics interpretations.** While there is wide consensus among physicists about the mathematical equations of quantum physics, there’s little consensus as to the interpretation of these equations, that is, what they imply about the nature of reality. I’ve usually relied on the Copenhagen Interpretation, the one that most textbooks currently present. If my explanation is specific to the Copenhagen Interpretation, I note that.

**Accuracy.** I’ve tried for accuracy. But, really, equations are going to give you the most accurate picture of quantum physics. Why? Because mathematics is not only a language, but, as Richard Feynman pointed out in his lectures on the character of physical law, math is also a system of reasoning. Unless one understands the math, one won’t get the fine points of the reasoning.

It’s kind of like a constitutional lawyer trying to explain, without quoting the Constitution and legal decisions, how one can commit a crime but not be convicted due to the police having failed to show a search warrant. The law, like math, has its own language AND its own system of reasoning.

**Analogies.** Many times, science writers use analogies. For example, they’ll suggest that electrons are like spinning tops. Well, that’s sort of true. But as electrons are thought of as having no dimensions, it’s hard to see how they could bear a close resemblance to a spinning top. Analogies often **are** helpful, but I’ll point out when I’m drawing an analogy.

I hope that you find these definitions helpful as you explore quantum physics. I look forward to your comments, corrections, and suggestions.

Alexis Shasta

January 24, 2017