Consider, next, the particles in our ideal boson gas. These particles, on dropping into
the ground state, become amalgamated into the condensate and hence are confined within a
certain volume. We have calculated above that the ground state energy per particle, at this
point, is then ≈0.77kTB. Let us compare this with the ZPE per particle, as estimated using
the Heisenberg uncertainty principle. From expression (2) above we can write