- The spatial decay of temperature nonuniformities in the weakly interacting Bose gas is studied bv utilizing Ma's low-temperature solutions of the Boltzmann equation. These results, which give exponential decay lengths varying as T-9, may be relevant to He II for T0.1 K. The longest two decay lengths, 1 and 2, are found to be in nearly a ten-to-one ratio, with 13.41103 cm for He II at 0.1 K. At higher temperatures the decay lengths are expected to decrease less rapidly than T-9 because of phase-space considerations, but an extrapolation to 0.3 K does indicate 1 to be on the order of 1 cm. Two types of experiments are suggested for determining these lengths. It is pointed out that information about phonon dispersion can be obtained from such measurements. 1974 The American Physical Society.