It's not as simple as that. When I tried this, long before reaching relativistic speeds the tips of the blades went supersonic, causing a cavitation effect that created an amazing amount of noise. Then, before I could turn off the fan, the suction or propeller effect ripped the whole fan assembly right out of the ceiling (it was set to Winter rotation) and when the fan hit the floor the housing shattered, releasing the fan blades (which were still spinnning madly by inertia, despite the wires to the fan motor having been severed in the fall), one of which narrowly missed hitting my head before embedding itself in the wall. Another smashed through the living room window, while a third destroyed an armoire with SWMBO's best crystal in it.

All in all, an expensive experiment. As much as I hated to give up the idea, I ended up having to install a conventional light fixture and call it good.

tanstaafl.