An ab initio theoretical expression for the N-body Lyapunov exponent o
f a dilute gas is derived. It shows the Lyapunov exponent to be a func
tion of the time integral of the correlation function for the second d
erivative of the interparticle potential (approximately a power 1/3 la
w). This establishes a link between the Lyapunov exponent and the tran
sport coefficients. We compare the theory with numerical simulations o
f a one component plasma.