Imagine for a moment that there is a box filled with some resistive gas. You are holding two probes a distance of X units away from each other in the center of the box. There should be some finite resistance between the two probes. Now imagine that the box is infinitely large, so that the gas extends infinitely in every direction. 1) In what units would one define the resistivity of the gas? 2) How would one calculate the resistance between two points in this infinite expanse? This has been bugging me for months!