FRB are the most distant known coherent sources of radiation in our universe, that exhibit an interference pattern under multi-path lensing, as arising from gravitational and plasma lensing. This probes space-time with unprecedented centimetre relative precision over gigapersecs of propagation, opening the possibilities of new classes of measurement. I will outline several potential approaches, including model-independent cosmic acceleration measurement (2004.11643), wave-optics microlensing (2002.01570), imaginary images (2103.08687), and more. I conclude with an outlook for the plausible future of FRB discoveries through upcoming and futuristic experiments.
