A big mystery arose from the Hubble Space Telescope (HST) observations of very distant supernovae carried out in 1998 that the Universe was actually expanding more slowly than it is today. The expansion of the Universe has been accelerating instead of slowing down due to gravity. No one knew how to explain the mystery, and it remains so until today.
Physicists came up with several explanations. Some of them posited that energy is a property of space a) and some other brought in the existence of a strange kind of energy-fluid that fills space. Both theories imply that such energy would not be diluted as space expands. The remaining simply challenged Einstein's theory of gravity and proposed a new theory which includes some kind of field that creates the cosmic acceleration.
Physicists could not say for sure which explanation was correct except that they offered a good solution … by giving it a name: dark energy b). They tried to explain on how space acquires energy from the quantum theory of matter. The so called empty space is actually full of virtual particles that continually appear and disappear. When physicists tried to calculate how much energy this would give empty space, they believed that the answer came out exceedingly wrong i.e. 10120 times too big. There is no way that physicists could explain such mysterious phenomenon as far as they stick to the Big Bang cosmology.
Now, under the Grand Relativity Theory, the mystery of dark energy could be revealed in a different way. Dark energy is nothing but the unfathomable gigantic 4D-Dirac and anti-Dirac energy seas contained “beneath” our 3D-universe (hypersurface) which effects are piercing through it (Figure-1). It was not surprising that physicists found that the vacuum energy was enormous, about 120 orders of magnitude too large than that of measured c).
The 3D-energy measured in our daily experience is merely the gauge against this huge 4D-vacuum energy. But why can’t we see this “dark” energy? This is the beautiful mystery of the higher dimensional spaces’ properties that most people overlook. The being that lives in 3D-world cannot see something that resides in 4D-world or higher. The 3D-electromagnetic waves d) can only propagate across the 3D-hypersurface, not off of it (Figure-2).
The universe’ expansion is the result of the gradual split of 4D-Dirac and 4D-anti-Dirac energy seas and its acceleration is caused by the tremendous strong opposite angular momentum exerted globally by those two opposite energy seas on either sides of the 3D-hypersurface e). Meanwhile, the local effect of such momentum exerting the orbital speed of galaxies we perceive as though clumped dark matters f) exist in there.
The 4D-dark energy is omnipresent, not necessarily in the far away galaxies but even extremely close to us piercing through within the inside of our body. Its effect could only be discerned within enormous astronomical scales. We may perceive it along the direction of 4th dimension (time-like distance) which, in fact, we cannot. It is from this same direction that the Hoyle C-fields or Higgs fields bombarding our 3D-universe (hypersurface) across to create and annihilate “normal” matter composing 5% of the total energy that affects our 3D-universe.
a. It is related to a long-discarded mathematical cosmological constant contained in Einstein's theory of gravity.
b. It turns out that this dark energy composes of roughly 68% of the Universe, the remaining is made up by 27% dark matter and 5% matter.
c. What physicists measured as [3D-] vacuum energy was in fact superficial i.e. the balance of those two opposite 4D-energy seas which, if not zero (mirror symmetry), is a relatively small number (skew symmetry).
d. There exist in grand cosmic higher dimensional electromagnetic waves which propagate in corresponding dimensional spaces.
e. You may refer this 3D-hypersurface as 3D-Dirichlet brane as the superstring theory does. The theory, however, should structure the brane similar to that for hypersurface in the Grand Relativity Theory. Or if you are religious enough, you may refer it to as Genesis’ 3D-firmament (firmamentum, Lat, raqia, Heb.) which lies between [4D-Dirac] water which is above and [4D-anti-Dirac] water which is below.
f. There is no such dark matter exists in nature. What one observes as the galaxies' fast orbital phenomenon is nothing but the effect of the tremendous strong opposite angular momentum exerted locally by those two opposite energy seas on either sides of the 3D-hypersurface (our universe). We can rule out, therefore, the use of gravitational lenses effect, as what some astrophysicists tried to do, as a tool to detect the existence of dark matter because the attractive gravitational effects attributed to dark matter are merely a side-effect of dark energy. Some physicists have already speculated that dark matter and dark energy is a single energy field that produces different effects at different scales, but they didn't know how to physically model it.