There is a source of energy that is not recognized yet, being the frequency reduction of free electric energy of photons.
The Dutch Paradigm postulates that all entities, being photons and neutrinos started with a frequency of approx. 10²⁴ Hz. The free electric energy is hF. It is the particle part of what is known as the particle/wave duality.
Photons can interfere with other photons and thereby transfer energy. The frequency of the free electric energy will reduce accordingly.
When we consider the Electromagnetic Radiation Spectrum
Source Electropedia
Then the question is obvious: why is there so much differentiation in frequency?
The answer as per The Dutch Paradigm is, that all naked photons with frequencies lower than approx. 10²⁴ have transferred energy accordingly to objects in space. The lower frequencies are photons that are exhausted from their free electric energy.
Therefore, illustrations as widely used, are impractical and confusing.
Source Ann Feild (STScI)
The idea of the Big Bang is spherical and not direction specific. Nevertheless, such illustrations are widely used, so apparently, there is merit for using to explain the several theories on dark energy.
The focus of The Dutch Paradigm is in Particle Physics. Therefore this source of “dark” energy is mentioned only. Accepting this postulate has important consequences for the build-up of inertia in objects. Kinetic energy in each object refers to its origin.
Therefore, each object refers to its origin, being the start of the universe, the position of the Big Bang.