Quote from EarthSky.org: Dark Energy is the name given to the mysterious force that's causing the rate of expansion of our universe to accelerate over time, rather than to slow down. That's contrary to what one might expect from a universe that began in a Big Bang. Astronomers in the 20th century learned the universe is expanding.
Quote from Nasa: Dark Matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly. We know that dark matter exists because of the effect it has on objects that we can observe directly.
Hence, both dark matter and dark energy are "invented" phenomena's, much like the planet "Vulcan", because we do not understand the mechanisms of the universe and because we have very limited insight into what causes the "gravity effects" we are able to observe.
While the classic physics and general relativity mathematics may look good and it works in the context of confirming a limited range of observations, we have no unifying proof to how the actual physics work. We don't even have a basic understanding into what really goes on. Devising dark stuff seems to be a stretch to far in the mind of the author.
The Principal Force theory explains why there's no need for dark matter and dark energy. In simple terms there's no need for any of the "dark stuff" as an obvious feature of the Principal Force is the universe acceleration and also the increase in push forces from outside large systems.
The Principal Force do push everything apart on a large scale (red arrows in the illustrations to the right) as the shadow effect is minimal, while it on a smaller scale allows objects to gather in clusters/solar systems/galaxies in the shadows of each other (green arrows). Keep in mind that the Principal Force is in abundance in the universe.
"Dark Energy" is the almost total lack of Principal Force shadows over vast distances that allows Principal Force waves to push the galaxies and distant astronomical systems apart. As the force applied is near constant the typical relative separating speed will increase according to standard physics. This is what is observed by astronomers.
"Dark Matter" is in fact the increased "pull" to the center of systems in limited astronomical systems, like galaxies and solar systems, that occur due to the Principal Force shadow effect. The composition and size of the objects within the scope will vary, but the same "forces" apply regardless. Objects are pushed together into planetary systems due to the increased shadowing effect in less distant systems.
This allows outer planets to rotate around a galaxy much faster than the current "gravitational" mathematics support, as the "gravity" is much stronger when calculated as a "many adjacent objects" system. This is what is observed by astronomers.
