What were the animated loops in the movie Thor: The Dark World supposed to be?
Were they wormholes? And what was the Aether proposed in there?
They are portals for connecting to other realms, 9 for now.
The things which didn’t return from the loop are shown in other realms in the movie later.
And portals were created due to Convergence.
During the Convergence, the Nine Realms of Yggdrasil are in alignment. This alignment causes the dimensional boundaries between each realm to become thin, resulting in various physical anomalies occurring at random. These phenomena include shifts in gravity, spatial extrusions, and the fabric of reality possibly tearing apart. Perhaps most notably, invisible wormholes that allow matter to move between realms are seemingly born and evaporate at random. - (Source:marvelcinematicuniverse.wikia.com)
Aether just got discovered due to Convergence.