Question: where did the a Swiss astronomer work most of his life, who proposed  a class of hypothetical redshift mechanisms that was proposed as an alternative explanation for the redshift-distance relationship?
Sentence (from "Streaming instability"): In planetary science a streaming instability is a hypothetical mechanism for the formation of planetesimals in which the drag felt by solid particles orbiting in a gas disk leads to their spontaneous concentration into clumps which can gravitationally collapse.
Relevant evidence: No