# Pauli's Wave Mechanics text. h vs. hbar

1. Dec 16, 2008

### Peeter

In this little Dover book "Wave mechanics", by Pauli, it appears to use h for hbar, and includes a footnote right on the very first page

"1. In these lectures we use the symbol h to denote the quanity 1.05 x 10^-34 joule.sec. In the older literature this quantity was usually denoted by $\hbar$"

However, this is what I've seen in the newer literature too. Are the definitions of these constants in a state of flux?

2. Dec 16, 2008

### f95toli

No, $$\hbar$$ should always represent Planck's constant divided by 2 pi in modern text.
I don't think I've ever encountered an example where someone has specifically used $$h$$ instead of $$\hbar$$ or vice versa. There are, however, examples of texts where the author is ex. ignoring factors of 2pi etc simply because they are interested in order-of-magnitude estimates and factors of the order of one does one matter.

Also, note that formulas where CGS electromagnetic units are used often differ by a factor of 2pi compared to the equivalent formulas in SI (and there are plenty of examples of papers where the authors have added/removed a 2pi too many).

3. Dec 16, 2008

### dlgoff

Last edited by a moderator: Apr 24, 2017