  It is generally considered that an atomic nucleus is always compact. Based on
the isospin-dependent Boltzmann nuclear transport model, here I show that large
block nuclear matter or excited nuclear matter may both be hollow. And the size
of inner bubble in these matter is affected by the charge number of nuclear
matter. Existence of hollow nuclear matter may have many implications in
nuclear or atomic physics or astrophysics as well as some practical
applications.
