|MadSci Network: Physics|
As far as we can and do know (and this does not include "forever"), the aggregate of energy and mass goes on "forever". Energy alone cannot be considered so, as, at the nuclear level, mass and energy are interconvertable.
The classical laws of thermodynamics speak of energy, alone, and by these energy does indeed go on "forever", but these laws predate modern nuclear physics and so must be amended as above to include energy and mass.
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