Dimension in physics

I have a solid understanding of topological dimension. I heard that some string theororists think that the universe is >= 10-dimensional, but that the extra 7+ dimensions are too small for us to encounter. How can a dimension be small; is it just a model for what is observed, or is it based in theory?

>>13
Though it is true that financial institutions often employ physicsists, none of these jobs are related to physics.  I think >>11 was wondering about jobs that require physics, which is quite rare.  I'm doing physics as well, and I'm not very optimistic.

>>14
I've seen that expression elsewhere before, but what does it mean?

>>15
Not necessarily... a good number of people are enslaved as post docs for decades.  Even among the professors, the non tenured ones don't have job security.  I'm going for whatever can unify the standard model and gravity.