Hasen�hrl 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 \ scriptstyle { m = ( 8 / 3 ) E / c ^ 2 } for the apparent mass; however, Abraham and Hasen�hrl himself in 1905 changed the result to \ scriptstyle { m = ( 4 / 3 ) E / c ^ 2 }, the same value as for the electromagnetic mass for a body at rest.
