Abstract

With several >~4 meter radio dishes in the outer solar system, it appears possible to measure the distances to fast radio bursts that originate hundreds of megaparsecs away and thereby measure the cosmic expansion history using a geometric method that is similar to the trilaterations of global satellite navigation systems (https://arxiv.org/abs/2210.07159 ; the recent winner of http://www.buchaltercosmologyprize.org).  The sensitivity scales quadratically with dish separations such that distance measurements to bursts even on the other side of the observable universe may be possible.   Not only could this technique potentially provide a much more precise geometric constraint on the cosmic expansion history, but such a mission could also provide interesting constraints on micro-Hertz gravitational waves, pulsars, the outer solar system, and the dark matter.   While this idea is ambitious, and there is certainly an argument that we do not need to measure the expansion better than we already have (which I will address), another reason to attend this talk is that this concept involves so much interesting physics related to GPS systems, very long baseline interferometry, plasma propagation effects, gravitational time delays, and the diffuse outer solar system.