Based on the preceding work on electromagnetic mass, Friedrich Hasenöhrl suggested that part of the mass of a body (which he called apparent mass) can be thought of as radiation bouncing around a cavity. The "apparent mass" of radiation depends on the temperature (because every heated body emits radiation) and is proportional to its energy. Hasenöhrl stated that this energy-apparent-mass relation only holds as long as the body radiates, i.e., if the temperature of a body is greater than 0 K. At first he gave the expression m = ( 8 / 3 ) E / c 2 for the apparent mass; however, Abraham and Hasenöhrl himself in 1905 changed the result to m = ( 4 / 3 ) E / c 2 , the same value as for the electromagnetic mass for a body at rest.