Unless one has a strong mathematical background, one new and perhaps puzzling concept in quantum mechanics is all the talk of ** eigenvalues **and

**.**

*eigenvectors*Making it even more confusing is that physicists tend to call eigenvectors *eigenstates* or *eigenfunctions*, and sometimes even refer to an *eigenbasis*.

So the obvious first question is, “What (or who) is an *eigen*?” (It turns out to be a what. In this case there was no famous physicist named Eigen.)