Can Space Time Be a Fluid?

We're asking the question, can space time be a fluid? It sounds like this is the idea that we're all just sitting in a hot tub somewhere. At this stage, it's really just an idea, but there are some fun experiments we can do to try to test it. The first one has to do with how light propagates through the universe. If you shoot photons across the universe, currently we think they arrive with the same energy as when they left.