Hi,
When you're in a "think & learn" mood, do try out:
(1) Flatland - a Romance of Many Dimensions by Edwin Abbott
- available as TXT ebook from Project Gutenberg or cheap at
Amazon.
- this is the one that helped me get semi-comfortable with multiple dimensions (4th? 5th?).
(2) Dragon's Egg by Robert Forward.
- available as paperback from
Amazon.
- the entertainment value is excellent AND it will help you see / ponder the practical implications of gravity on a neutron star, relativity and so on.
It's been a while since I read either, but both are keepers and will always live on my bookshelves.
For just plain, escapist FUN, try anything from Lois McMaster Bujold, especially her Miles Vorkosigan books. Start with Cordelia's Honor and work from there.
RocketGranny