On the relativistic theory of rocket flight
It is shown by macroscopic analysis that, when the entire mass of a rocket is consumed for creating thrust, objects may be obtained as a result having energy but zero mass, moving with the velocity of light. It is shown that the boost process of such massless objects can be realized in finite time from the observer's point of view. The vast stellar luminosity of quasars and certain jet motions observed in remote space can be explained by the production of massless radiation with internal motions connected with the separation of large energies inside the stars.
scientific article; zbMATH DE number 4026868