the magnetic radiation reaction force is the result of the most fundamental calculation of the effect of self-generated fields. it arises from the observation that accelerating non-relativistic particles with associated magnetic moment emit radiation. the abraham–lorentz force is the average force that an accelerating charged particle feels in the recoil from the emission of radiation. the introduction of quantum effects leads one to quantum electrodynamics. the self-fields in quantum electrodynamics generate a finite number of infinities in the calculations that can be removed by the process of renormalization. this has led to a theory that is able to make the most accurate predictions that humans have made to date. see precision tests of qed. the renormalization process fails, however, when applied to the gravitational force. the infinities in that case are infinite in number, which causes the failure of renormalization. therefore general relativity has unsolved self-field problems. string theory is a current attempt to resolve these problems for all forces.