A rigid box contains two compartments separated by a partition. On one side is an ideal gas consisting entirely of green particles, while the other side holds an ideal gas of entirely red particles; the two particle types have the identical masses. The partition is removed. Both Jane and Bob watch this process, but Bob is color blind and cannot tell the difference between green and red. Jane claims that the entropy of the world has increased and thus work must be done on the system to return it to its original state. Bob claims that there has been no entropy change, the process is reversible, and no work is required to return the system to its original state. Both claim that their analyses are consistent with the laws of thermodynamics. How can both of them be correct about the work? Explain.