The number, size, surface area and shape of cavities in the hard-spher
e crystal and dense fluid were studied by simulation. The number n(c)
of cavities per sphere is given over about 60 orders of magnitude by -
ln{n(c)} = pV/NkT - 1 + F(z) with F(z) almost-equal-to 0.6 + ln {z} in
the crystal and F(z) almost-equal-to -2.5 in the dense fluid. The ave
rage cavity volume [v] is given by ln[v] = DELTAS/Nk - ln{N/V} + F(z),
where DELTAS is the entropy relative to an ideal gas. z is the densit
y relative to close packing. The equilibrium number of vacancies per s
phere in the crystal is n, = n(c)/(1.2z - 0.45). The cavity shape fact
or a(z), defined by pV/NkT = 1 + a(z)/[v]1/3, is close to the sphere d
iameter sigma. The assumption that a(z) almost-equal-to sigma predicts
the measured values of [v], [s] and n(c), for the crystal, to within
their uncertainties.