I would like to offer a context for considering and discussing the principal of Relativity. It is abstract but is derived using an anti-reductionist train of thought (i.e. bottom - up) rather than the conventional top - down.
- The Universe has been shown to be Relativistic, however this tends to lead to a unsatisfactory position regarding the basis from which we can derive our starting position. Intuitively, the position would be most easily considered as a consequence of the only Absolutes, namely 0 (nothing) & 1 (Infinity/God, everything) - in Philosophical terms it is often illustrated as the Yin Yang. Our Universe does not contain either, so the inference is that it must be the boundary/potential/tension/equilibrium between them.
So, from nothing - No Time, No space:
This is always going to be the 'leap of faith', however even before Time (1st dimension not 4th IMO, contrary to mainstream scientific thought), we can imagine a 'potential observer' as a point with zero spatial freedom, but requiring Time. The concept of Time in this framework is reduced to a state of potential, as are all subsequent derived spatial dimensions - this is supported by Quantum Mechanical observations. Conservation dictates that this leap requires a strong constraint - Strong Nuclear (pointlike, high localised magnitude)
To intellectually grasp this imaginary 'potential observer' we must recognise that it incurs an additional potential to keep it distinct (i.e. Relative). Therefore our framework must incur two potential frames of reference to fully appreciate the initial proposition. This separation is the minimum necessary to resolve the characteristics at play - It is, I believe, the very essence of Einstein's theory (consistent in all potential reference frames). This additional potential is the 1st spatial dimension and incurs a force to conserve, namely Electromagnetic (linear, polar attribute, positive/negative, attraction/repulsion)
To resolve these two dimensions it is necessary to create an additional potential, the 2nd spatial dimension - all equal points being represented by a circle on a plane. Conserved by the Weak Nuclear force which governs the Electron orbit. (Circular, Orbital: Complex Attraction due to increased degrees of freedom)
To resolve these three dimensions.......Gravity. (Spherical, extensive range thus dilute/weak)
Throughout these translations we have encountered the 'observer' driving the evolution/potential whilst incurring a known fundamental force (constraint) in the process of conservation. Geometrically the influences of both aspects appear to reconcile.
The use of an additional/outside frame of reference to understand the nature of our Universe is, I believe, the only way to give context.
Furthermore the translation to 5 dimensions incurs a toroidal geometry synonymous with Galaxies, and is suggestive of an additional Fundamental Force (Dark Energy?) - which is only apparent on such scales but constrains all within.
This is my attempt to put Relativity into words and may well be hidden within the complexities of the Mathematics that I do not understand, and therefore unoriginal....but I hope approachable.
Rgds, Skaff.