Newton's Third Law in the Framework of Special Relativity
Newton's third law states that any action is countered by a
reaction of equal magnitude but opposite direction. The total
force in a system not affected by external forces is thus zero.
However, according to the principles of relativity a signal can
not propagate at speeds exceeding the speed of light. Hence the
action cannot be generated at the same time with the reaction
because the information about the action has to reach the
affected object and the affected object still needs additional
time to react on the source, hence the total force cannot be
null at a given time. The following analysis provides for a
better understanding of the ways natural laws would behave
within the framework of Special Relativity, and on how this
understanding may be used for practical purposes.