APOD: Cosmic Microwave Map Swirls Indicate... (2014 Mar 18)

[Chris Peterson]

My real question is, “Are there still investigations that attempt to use an “unseen medium” as a theory or basis for describing some of the mysteries in our observable universe?” Has the astronomic ether disappeared as did the medical variety with the advent of new and different theories?

An actual medium? No, I don't think so, although some of the ideas about hyperuniverses might border on that. Likewise for theories that attempt to identify some sort of absolute reference frame.