So I've read that electrons traveling inside a sheet of graphene are said to travel "masslessly". I'm interpreting this as meaning "zero apparent mass" and not zero actual mass. Presumably, the graphene doesn't somehow weigh less than the sum of its constituent electrons and nuclei. But given this extraordinary massless behavior by the electrons in the graphene, can it be said that work has been done on the electrons to make them behave this way? If so, then what is doing the work? Where is the energy coming from to cause this unusual behavior of the electrons?