The non-string, non relativistic version. Consider two points of mass M rotating in a circle of radius R and joined by an spring of constant K. Now we split the spring in a position x < 2R, adding two equal masses m in broken extremes. Assume energy and momentum is preserved. Describe the evolution of the system. My question is, does the classical string action, based on world surfaces, reproduce aproximately this system? Next, we could consider the relativistic version, where the mass m that we add is to be equal to the energy we substract from the system. Can the spring split in this case? Now I think about, is there a relativistic version of Hooke's law? In any case, the question is the same: how does the system compare to the string action?