Relativeness of energy and mass density manifested by space–time non-symmetry

•Microscopic/macroscopic are mutually supportive for they are parts of the same entity.•Their physical properties are intrinsic of the ST being highly NS and NH.•Interchange of EMD reflects STNS and NENH of the expanding universe.•Exploration of unknown substance involves making hypotheses at galactic scale of ST.

The microscopic and macroscopic are mutually supportive for they are parts of the same entity. Their physical properties are intrinsic of the space–time being highly non-symmetry and non-homogeneous. The interchange of energy and mass density (EMD) reflects the space–time non-symmetry (STNS) and non-equilibrium and non-homogeneity (NENH) of the expanding universe. As such, the trade-offs of energy and mass density are scale and time dependent. The proportion of the “light matter” to the so-dubbed “dark matter” reflects only the very early stage of the journey from the big bang to the big crunch, both of which are disputable propositions. The light matter refers to the ordinary matter, while the dark matter differs in ways that are unknown.The exploration of this unknown substance, which may not even be matter in the ordinary sense, involves making hypotheses at the galactic scale of space–time. One of them is the idea of a “cosmological constant” that provokes dubbing dualism to pair with monism, the self-fused supreme (SFS). The SFS is assumed to prevail in another dimension of higher order space–time. Only, SFS possesses the secret of perfect symmetry and homogeneity, in opposition of dualism.The search for the dark matter has prompted the Euclid mission of the European Space Agency (ESA) to study the ways with which the energy density could depend on time or being a constant. To this end, the changeability, inhomogeneity, and mobility (CIM) of the galaxies deserve consideration. An explanation for the illusiveness of the dark matter is offered by Tao Te Ching in connection with the changeable and unchangeable. The dark energy and dark matter are subject to change as they have already been named. The so-dubbed “dark spirit” as the “mysterious one” is the only unchangeable.