If you shine a flashlight into a foil balloon then popped it in a dark room, would you see the light?
NoSome of the light energy is lost every time it is reflectedA good aluminium optical instrument quality mirror will reflect about 95% of the light energy falling on itAn ordinary foil coating would be much worseLight travels about a foot (30 cm) in a nanosecondSo if you had a balloon a foot across, the light inside would have reflected 1,000,000,000 times for each second it took you to take it into your dark room! With more than 5% (a twentieth) disappearing at each bounce, it would be long gone!
