The universe could be a Bose-Einstein Condensate. A BEC is a superfluid that exhibits no friction. This superfluid forms an aether in which electromagnetic waves propagate. Matter and mass involve the interaction of vortices within the aether. This leads to the quantum vortex theory of matter.
Gravitational waves have been measured in 3H-B BEC superfluid by a group in Finland. Now Gravity waves produced by merging black holes have been measured by sensitive laser interferometers at the Advanced LIGO facilities. The detection of gravity waves confirm predictions made by Einstein's General Theory of relativity. These gravity waves may also support the superfluid vacuum theory of the Universe.