Now imagine reflecting objects at various locations in that room, and an obscuring object in the line of sight so you can't see the LED directly. You can see light from that single point source from various locations in the dark room, but cannot see the origin.
That's what the GP is asking, I think. How do we know the patterns we see aren't reflections or interferences that could be traced to a single point source?
I don't think there exist enormous radio-reflecting objects in space, let alone ones that let through visible light perfectly. And there are many of these circles, so it seems unlikely that all of them could have their source obscured.
That's what the GP is asking, I think. How do we know the patterns we see aren't reflections or interferences that could be traced to a single point source?