Let q ∈ (0,1). We know that, when q tends to 1, we recover “classical” quantum mechanics. However, when q is not equal to one, we have a theory of quantum mechanics in a spacetime, i.e., a theory where the vacuum has a nonzero energy density. As a q‐analogue on the space variable of the wave equation, we introduce the q‐space wave equation. Solutions of these equations are given for q ∈ (0,1) and for q⟶0. Since some states have more spin degrees of freedom than the physical particle has, the q‐space wave equations remove the additional degrees of freedom.