Namely are you going to view things from the point of view of
somebody rotating with the pipe or someone in an inertial frame? If
you mean the latter, then there is an artificial gravity even for
objects inside the empty space.
Oops! I meant to say "the former" not "the latter" above!
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu http://physics.usna.edu/physics/faculty/mungan/