I have a explaination for the dark énergy, this is because the space can have a variabilily density.
   The variability density is because the space in heap'galaxy has a very more great space density and when the galaxy become
much near one to other,then the space in the heap'galaxy that go in the space between heap'galaxy become less dense and from this they are
a dilatation'space between heap'galaxy.
       I have a example to show this phénomenon;
if you put a liquid métal in a nearly full'box of métallic ball, then because the solid métal is more dense,then when it become liquid there is a variability density and the liquid in the box can overflowing.
   Here instead of métal ball,it is heap galaxy and instead of métal liquid, it is space between heap'galaxy.
             I have a mathématical équation for this phénoménon:
D1(variation of V1) = D2(variation of V2)
      D1 is the density of the space in the heap'galaxy, variation of V1 is the variation of the volume space in heap'galaxy.
      D2 is the density of the space between the heap'galaxy, variation of V2 is the variation of the volume space between the heap'galaxy.