  There is considerable evidence that the heavy fermion material UTe$_2$ is a
spin-triplet superconductor, possibly manifesting time-reversal symmetry
breaking, as measured by Kerr effect and muon spin resonance experiments below
the critical temperature, in some samples. Such signals can arise due to a
chiral orbital state, or possible nonunitary pairing. Although experiments at
low $T$ appear to be consistent with point nodes in the spectral gap, the
detailed form of the order parameter and even the nodal positions are not yet
determined. Thermal conductivity measurements can extend to quite low
temperatures, with varying heat current direction can therefore provide
information on the order parameter structure. Here we derive a general
expression for the thermal conductivity of a spin triplet superconductor, and
use it to compare the low-temperature behavior of various states proposed for
UTe$_2$.
