Growing evidence that the universe is connected by giant structures (2019)
There's a theory out there that our universe is a pocket universe inside of a supermassive black hole.  My relativistic gravity is pretty rusty and was shaky to begin with. If that theory isn't pure fantasy, and we were a pocket universe, <i>and</i> large masses were spinning above the event horizon, we'd experience forces from those objects, right?<p>I'm still kinda fond of the Flatland theory myself.  Us poor 4 dimensional beings can't figure out how to build tools that can take 5 dimensional measurements, so we see weird behavior we can't explain.