In Doctor Strange, the fight scene between Steven Strange and the zealot shows that someone's astral form has limited interaction with the physical world (only violent actions ripple into the physical world).
At the same time, one scene shows Dr. Strange learning in his astral form while his body is resting. He is holding a book:
How did that book get there? I was under the impression that the astral form is related to the spirit being pushed out of the body (and that would be it), not that there is a parallel world where every object has an astral form as well.