  For general $\beta \geq 1$, we consider Dyson Brownian motion at equilibrium
and prove convergence of the extremal particles to an ensemble of continuous
sample paths in the limit $N \to \infty$. For each fixed time, this ensemble is
distributed as the Airy$_\beta$ random point field. We prove that the
increments of the limiting process are locally Brownian. When $\beta >1$ we
prove that after subtracting a Brownian motion, the sample paths are almost
surely locally $r$-H{\"o}lder for any $r<1-(1+\beta)^{-1}$. Furthermore for all
$\beta \geq 1$ we show that the limiting process solves an SDE in a weak sense.
When $\beta=2$ this limiting process is the Airy line ensemble.
