This past weekend I was watching Cast Away starring Tom Hanks. I watched starting at the time when he was on the plane. He was marooned on the island and was learning to survive by himself with no tools and modern equipment. Then the movie flashed forward to a couple years later and it showed him catching a fish using a spear. I thought that it was just Hollywood appeal because every time I moved towards a fish it darted away. Bu that's because the fish could see me. In the movie, Tom Hanks is far away when he throws the spear so the fish can't see him due to internal reflection. The fish's angle of incidence if looking at Tom would be past the critical angle which means that everything the fish saw would be a reflection of underwater. However, Tom could see the fish because his vision is moving from a fast medium to a slow medium which has no critical angle. This was how he was able to spear the fish.
