@Charles - I was aware of the table, I guess my definition of "separate entity" is a bit different given their existence is tied to the lifetime of the books associated with them. And the problem with truly treating them as a separate entity I think manifests itself in particular when you start to figure out how to integrate them into the GUI.
The screenshot is interesting. In some ways it is ideal, in that as a user you can quickly move between the author and the book. Having a popup dialog for the author "loses" in comparison with the modality issues.
However I do 100% agree with Charles that it should not become the "recommended" approach, it is just a workaround that those who are desperate can use. Think of all the issues it causes - that your access to the author information is limited to how you have done your search, the sensitivity to sort order, the "noise" it adds to the library view, the false positives it returns for plugins like Find Duplicates etc.
Perhaps an alternative approach would be if the book details pane could be tabbed or something, to allow switching between book detail and author detail... with the author details stored in the Authros table as Charles was suggesting... just thinking out loud...