Board Thread:Lore Discussion/@comment-121.217.164.118-20130929050443/@comment-26498092-20150615054506

Personally, I believe Kagrenac's experiments worked and when he tapped into the heart of Lorkhan's power, one of two things happened, he either created a plane of oblivion for all of the dwemer and transported all of them who were in the realm to that plane, or the more likely one is that he sent every dwemer to the Void. The Void one makes more sense because it happened all at once and since very few people can live/know about what happensin the Void it would be very hard to find them. It would also make sense when Arniel uses a weaker Keening (we know it's weaker because he obviously doesn't have on Wraithguard and doesn't die instantly) on a warped soul gem he gets transported to possibly where the soul gem came from, the Soul Cairn and that's why he's summonable. As for the Dwemer, I believe that since they had a more powerful Keening, Sunder, and the Heart of Lorkhan all of the Dwemer were transported to where the Heart of Lorkhan came from, Sithis. That would mean that the entire Dwemer race is simply floating in the Void, because Yagrum couldn't find them in the outer realms and I'm not certain about Vivec being able to sense the entire Void for the Dwemer.

TLDR: The Dwemer are in the Void and Arniel is in the Soul Cairn because Keening transports the user, or when used with Sunder the entire race, in that plane to the plane where the item it's used on.