Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Every book I borrow have have this number in them. Even my library categorizes them with this number. Is it a universal particle physics book number?

share|cite|improve this question

closed as off-topic by John Rennie, Brandon Enright, David Z Mar 12 '14 at 16:05

  • This question does not appear to be about physics within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

I am interested in opinions as to the topicality of this questions. I'm leaning toward off-topic myself, but I don't think we have ever discussed it. – dmckee Mar 12 '14 at 15:36
This question isn't about Physics – John Rennie Mar 12 '14 at 15:38
@JohnRennie, well, it's a bit odd. To those who already know the answer, it's clearly not about physics. However, to someone who doesn't already know the answer, it's not inconceivable that a label consistently appearing in a set of physics books could have had some kind of physics-based significance. How do you treat a question that you can only identify with confidence as "not physics" if you already know the answer? – user27578 Mar 12 '14 at 15:47
This question appears to be off-topic because it is about library science. – David Z Mar 12 '14 at 16:05
Cases like this are so rare that I don't know if we really need a formal policy. We can just leave this here, on hold, and people will be able to find it, but it'll still show up as not being on topic. – David Z Mar 12 '14 at 16:06

It's an identification number for a classification scheme called the Dewey Decimal System. It's just a general system most libraries use for organizing books by subject matter; the numbers don't mean anything. 500 is the Dewey series for science, 530 is physics, and 539 is modern physics.

I don't know if this question is really appropriate for Physics.SE, but then, I don't know if any other SE would be.

share|cite|improve this answer
Yeah, where do you post this question? I searched google, no answer no question. At least now it has been asked and answered somewhere (here). – Faq Mar 12 '14 at 15:40
I think it could be really useful to have a to ask questions that come up in the life of a physicist, but are not directly physics. Alternatively one could think about allowing them on, which is right now only meta Q&A for the site itself. – jdm Mar 12 '14 at 15:55

539.7 is the code for Atomic and nuclear physics books in the Dewey Decimal Classification system. For more informations about it, check the wikipedia article

share|cite|improve this answer
Ahh yeah, our library just recently switched to these funny numbers, and then of course I started noticing these numbers in books, all over the place . – Faq Mar 12 '14 at 15:39
@LoveLearning, "just recently"? It seems surprising to me that a library would only now start using the standard for library organization of nonfiction books. Is it an especially small library? – Brian S Mar 12 '14 at 16:22
Perhaps they used it internally, but kept it hidden from our eyes. – Faq Mar 12 '14 at 16:24
How were you able to find books if they weren't labelled? – user37496 Mar 12 '14 at 16:54
The books themselves where labelled (with name and number I think), but the shelves where labelled with names (e.g. PhysTheo something something) rather than these numbers (if I recall correctly). – Faq Mar 12 '14 at 17:27

Not the answer you're looking for? Browse other questions tagged or ask your own question.