We report on the conductance of multiwalled carbon nanotubes as a function
of voltage and temperature between room temperature and 4.2 K. The data sho
w a monotonic decrease in conductance as the temperature is lowered. At tem
peratures below about 20 K, a nonlinearity develops in the V(I) data, corre
sponding to a pronounced dip in the conductance near zero bias. The size of
the dip increases as the temperature is lowered. The data are explained in
terms of transport through a Luttinger liquid. The measured conductance co
ntains contributions from the nanotube-contact interface and from the nanot
ube itself.