Consider the thermal Casimir effect for an ideal Bose gas whose dispersion relation includes both quadratic and quartic momentum terms. If a macroscopic body with spatial dimensions $d\in\{3,7, 11, \dots\}$ is immersed in a fluid with critical temperature $T_c$, the Casimir force acting between them is We demonstrate that it can be characterized as It is a sign that depends on the separation $D$ between objects, changing to be attractive when far away and repulsive when far away. The result is an effective potential that joins the two objects at a finite distance. For odd integer dimensions of $d\in \{3, 5, 7, \dots\}$, the Casimir energy is a polynomial of degree $(d-1)$ in $D^{-2}$ indicates We point out the very special role of the dimension $d=3$. Here we derive a surprisingly simple form of the Casimir energy as a function of $D$ in the Bose-Einstein condensation. We describe the crossover between monotonic and oscillatory damping of the Casimir interaction above the condensation temperature.
