Physicists don't know what "dark matter" or "dark energy" is or does, so why should the average person?
There are several theories to explaim the accelerating expansion fot he univers, but none are yet very satisfactory. It could be some sort of low energy matter, some extra-dimensional force, or the warping of spacetime itself (kinda like rolling downhill)
Earlier this year I discussed this with Dr. Sylvester Gates (father of supersymmetry and world reknowned researcher in cosmology and superstring theory).
He doesn't know what you suggest everybody should know.
I asked him if it was possible for energy to be transferred between our dimensions and those additional 6/7 dimensions. he said that not only is it posible but that it will likely take the form of particles.
So I asked if that energy could be the source of the accelration. He said they thought about that several years ago, but that now it may be worth reconsidering the idea.
We still do not have even fully satisfactory mathematical frameworks to explain the physics of the universe. We have to change our assumptions and frameworks everytime we change the scale or nature of our investigation.
I am not convinced we even properly understand our current dimensions, nor the affects of space. We do not even understand all the properties of space. (yes, space has properties that affects the flow of energy)
Cosmology is in a bit of turmoil right now (since 1998). We cannot explain the acceleration; we cannot explain how we came to exist aqs life when so many universal constants had to assume very precise values. The slightest variation in any one of 12 or more constants would mean life could not exist, or even that protons, neutrons, atoms might not exist (no coalescence) thus just sheer clouds of energy.
To account for some of this they bring up ideas like the multi-verse to hamdle the huge improbability of our existence. (a very, very unsatisfying theory but practically the only one currently available that does require the pre-existence of a Creator)
Even superstring theory has not been experimentally validated.
So if some website is stating such grand facts about the cosmos then they are leading you on. They are full of it, and have some other agenda to take your money, no doubt.
P). W
P is deceleration which you CAN feel/sense....as TIME.