<unk> <unk> <unk> <unk> <unk>  Passage: Heavy ions that are spherical when at rest should assume the form of "pancakes" or flat disks when traveling at nearly the speed of light. <unk> <unk> <unk> <unk> <unk> <unk>  Question: What must be considered when explaining results from particle collisions?
density due to length contraction