I believe Larry Niven posed this question in one of his short-story collections years ago, but for the life of me I can’t remember whether he had an answer or which book it is in.
Basically, let’s say you have a large sphere (large enough for somebody to fit comfortably inside) that is mirrored on the inside. You bring it up into space and have somebody float in the center(obviously, the sphere would need to be constucted in two pieces and assembled around the observer).
The observer then turns on his flashlight. What will he see? Will he see a solid wash of light from all directions? A single light in whatever direction he looks? Something else? Would it matter if the light sourse was a flashlight that only shines in one direction or a point light source that shines in all directions at once?