Who need an usher to show them the way to unfamiliar territories? Who need in the darkness of a theatre? Who need in the direction of the rising sun or setting sun? The first need is the reflection of a penlight pointing away. The second is a light source approaching. The third is a light source receding. All three describe all possible quantum states or continuous states of the universe at every spacetime instances.

The common sense definition of a force is either a push or a pull. Relatively, who is the pusher or the puller remains ambiguous without a light source. In total complete darkness nothing moves linearly, however, something can move tangentially, for example, a rotation. The important question is how does a rotation sustain itself perpetually? The answer is another rotation such that if one is going clockwise then the other is going counterclockwise. If one is spirally outwardly increasing then the other is spirally inwardly decreasing thus maintaining topological structure invariance. It is the same ancient yin-yang principle of antiquity. What is old antique is also new unique, vice versa. In this sense, a true light source never grows older or gets younger. Equivalently, it is a directional invariance with eight properties: right-fore-top, left-fore-top, right-fore-bottom, left-fore-bottom, right-back-top, left-back-top, right-back-bottom, and left-back-bottom.

All eight properties must exist for a state of absolute perfect symmetry. Odd numbers of these properties: 1, 3, 5, 7 give fermionic mass symmetries. Even numbers: 2, 4, 6 give bosonic energy symmetries. The exact number 8 is exclusively reserved for the perfect symmetry of the true absolute quantum vacuum states of all spacetime events.