  The hydrogen atom is supposed to be described by a generalization of
Schr\"{o}dinger equation, in which the Hamiltonian depends on an iterated
Laplacian and a Coulomb-like potential $r^{-\beta}$. Starting from previously
obtained solutions for this equation using the $1/N$ expansion method, it is
shown that new light can be shed on the problem of understanding the
dimensionality of the world as proposed by Paul Ehrenfest. A surprisingly new
result is obtained. Indeed, for the first time, we can understand that not only
the sign of energy but also the value of the ground state energy of hydrogen
atom is related to the threefold nature of space.
