Key points are not available for this paper at this time.
We review three distance measurement techniques beyond the local universe: (1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and (3) HI intensity mapping. We describe the principles and theory behind each method, the ingredients needed for measuring such distances, the current observational results, and future prospects. Time-delays from strongly lensed quasars currently provide constraints on H 0 with < 4% uncertainty, and with 1% within reach from ongoing surveys and efforts. Recent exciting discoveries of strongly lensed supernovae hold great promise for time-delay cosmography. BAO features have been detected in redshift surveys up to z 0.8 with galaxies and z 2 with Ly- forest, providing precise distance measurements and H 0 with < 2% uncertainty in flat CDM. Future BAO surveys will probe the distance scale with percent-level preci-
Suyu et al. (Wed,) studied this question.