Question regarding a contradiction in conservation laws

[zeromodz]

We all know that the universe is expanding and for that matter accelerating. Science is now starting to realize that the universe will expand forever and the big crunch will never occur due to recent data of a supernova. My point to all this is, quantum theory states that a vacuum must always have more energy density than its potential well due to the uncertainty principle. If the universe is expanding, it loses energy density with time. So eventually there will be too much space and the energy total energy in the universe will not be enough to cover all of space. So either, the uncertainty principle will fail, the conservation of energy will fail, or the universe must stop expanding. What do you think?

 

[Dale]

Energy is a notoriously tricky concept in any situation where the spacetime curvature is significant. Particularly if the metric is not stationary, as is the case in the FLRW metric.

http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html