I'm re-watching Lawrence M. Krauss's Cosmology Hakunetsu Kyoshitsu, and he discusses dark mater/energy and the expanding universe.
I wonder if the concepts of dark energy and dark matter are only a misunderstanding of "space".
As Einstein taught us gravity is a warping of space caused by matter.
"Warping" has been a bit of red herring for me, as it is often described as a flat sheet with small an large "ball" placed on it, and when you put the small ball down it is "attracted" to the larger due to the indention of the sheet. This is a warping, but it reality, I think it may be more accurate to describe it as a compression of space.
In other words, a mass has a compressing effect on the space around it.
Now the common belief seems to be that space is a separate "entity" from matter. I think it may be this belief that has lead us to the concepts of "dark matter & energy".
However, what if energy/matter are interlinked with space. In effect a quantity of matter is linked with a quantity of space. So that multiple quantities of matter at the same location would increase the "density" of space for that area.
How does this apply to the expanding universe and dark matter/energy?
What if the "empty" space between galaxies is not as "full of space" than we currently think.
Without space to "hold" galaxies together, perhaps they would expand and accelerate away from each other. Much like when you take gum, stretch it and let half drop to the ground. As the gum streches and less and less of it hold it to the other half it begins to accelerate toward the ground.
It's probably simple to test this idea with maths... but not simple enough for me, at least at this moment...
Maybe some day I'll take a look at the numbers...