thought experiment

(One thread inspires another. ;) ) If a large spherical hollow chamber, perhaps 1000 miles in diameter, was created with its center exactly at the center of the Earth, what gravitational force would be felt at various points within the sphere?

If an astronaut, equipped with a flashlight, was floating inside a sphere with a perfectly reflective surface, what would he see? Is there any software which could render his view approximately, or can it be figured out just with pen and paper?

Has anyone seen these before? It's an evolutionary thought experiment which looks really cool. This guy has a great imagination, and he's a wonderful artist. Many of his animals look a bit ludicrous, but then again many of the real world's animals look equally ludicrous...

I was reading about a version of the famous Shroedinger's Cat thought experiment known as the "Quantum Suicide" thought experiment, and I was reminded of the Million Dollar Challenge and whether it would be applicable here. According to wikipedia: If I where to set up this experiment, sit in...