Establishing a Basis of Interpretation and Physical Context
First, one has to establish a physical context in order to understand what Einstein's equation describes and all its implications. And what better place to start than at the atom, say a simple hydrogen atom, the building block of visible matter? The hydrogen atom will be our basis of interpreting Einstein's equation and we will see that Einie's equation serves as a sweeping schematic of the H atom's form which can be refined by reason and imagination.
Energy, in Einie's equation is the hydrogen atom's capacity to do work. Its a sort of raw potential equation, prior to taking motion into consideration. A H atom's potential to do work is proportional to it's mass and velocity of light squared. Mass and c2 coupled on the right side of the equation hints toward an assumption that the invisible (dark) subatomic objects that mediate light and gravity to and from all atoms of the Universe are one and the same. Furthermore, the H atom takes on its form from these invisible subatomic objects, all of which converge from none other than all other H atoms of the Universe. And logically the next assumption is that these set of dark subatomic objects interconnect all atoms of the Universe (and/or all protons and neutrons).
One could imagine a hydrogen atom as a bundle of gazillions of these subatomic objects converging and superposing from all the atoms of the Universe and imparting form to it at a central location which is the atom. Gaede called this subatomic object the EM Rope. Imagine an inordinately long double stranded threads indissolubly connecting all atoms. It is the presence of these gazillions upon gazillions of EM Ropes converging into a central bundle we call atom (or proton/neutron) that gives the H atom its enormous potential to do work, especially in a nuclear reaction. These dark subatomic objects impart form to the Hydrogen atom, and so the atom and these subatomic objects are somewhat the same and yet there is an inequality since in order to build a Hydrogen atom we need as many as these subatomic objects coming together as there are Hydrogen atoms in the Universe.
An atom has the ability to tap into the EM Ropes, or work it and are worked by it, by various means, for example in a nuclear reaction, a chemical reaction, in atomic electron transitions, etc. In these sort of mysterious and ethereal phenomena, the atom taps into the very set of subatomic objects from which it derives its form. And all of these subatomic objects keep a single H atom in tension with all other atoms of the Universe and this is called inertial mass. Gravity/Inertia is tension of these supposed dark subatomic objects. Light (or radiation) is torsion of these same invisible subatomic objects which a. converge to impart form to the H atom, and b. interconnect all H atoms (or protons and neutrons) of the Universe.
This subatomic object has some unique properties not associated with macro-objects, but it still obey's Newton's third law, or rather we can use Newton's third law to describe this object. For every action there is an equal and opposite reaction. The subatomic objects that interconnect all atoms, impart form to them and mediate both light and gravity obey Newton's law. So when an atom taps into these or acts, the EM Rope has an equal and opposite reaction always toward at least two atoms of the Universe. Thus the square factor. This is how light is able to retrace its path so to speak. Its almost like strumming a chord and the chord reacts in both directions where it ends on at least two atoms. The c2 concept is a to and from idea. Bidirectional.
Newton's Third Law: action, equal and opposite reaction is the easiest way to understand the c squared concept in Einstein's equation. If the atom at one location torques a set of superposing EM Ropes, it would seem that the EM Ropes would be signalling in two directions, say N & S along the double stranded threads. The threads are signalling in two directions. Some of the EM Ropes will end and transform into the atom that enacted the light event, and others will end at other atoms. The light event will react back through the atom that enacted as well as end on other atoms. If at different locations of the atoms the torsion events are happening at different frequencies, perhaps the highest at any given time is the set of superposing EM Ropes that will cause the recoil. Einstein said,
Outgoing radiation in the form of spherical waves does not exist [he meant does not happen]. During the elementary process of radiative loss, the molecule suffers a recoil of magnitude hv/c in a direction which is only determined by ‘chance’, according to the present state of the theory." (On Quantum Theory of Radiation)
Radiative loss, could just refer to any location of the atom that suddenly increases its frequency of light events along the superposing set of EM Ropes aligned at that location. The chance is just an illusion. I think the chance has to do with the number of EM Ropes and my supposed electron threads in an aligned superposition around the atom, and this will always increase or decrease in accord with extraneous EM Ropes and motion and realignment of electron threads. No one has the ability to count them so we use quantum jump concepts as well as the almighty random variable and statistics. But I think light, like gravity, is a strength by numbers relation.
Another way to think of it is that by assumption that all that atoms of the Universe are connected and formed by these subatomic objects . . . light behavior constantly acts through the H atom, equally, from opposite directions, and this may in someway help maintain its structural integrity. Or the H atom can signal equally in opposite directions via the mediators. This implies that light or radiation is always working to and from all atoms. Structurally, this further implies that an H atom derives its form from one and the same set of objects that mediate light between all atoms, and these same objects also maintain mass, and are also involved in what we call gravity. An atom constantly tapping into these subatomic objects keeps a constant action/reaction tension between all atoms that is basically inertial mass, and is exponentially increased in gravity when we model objects like Sun & Earth at close distances. But it would seem that all the atoms of the Universe are inseparably connected via the mediator of light and gravity. There is a perfect, profound, balanced and consistent connection and activity happening between them all. I guess we can say that God made all atoms well, perfect, symmetrical, clear, and Einstein's equation can be used to describe this.
Another way to interpret c2 is to say that the H atom has an ability to emit and absorb at a characteristic range of frequencies. In either emission or absorption the atom is simply relaying along our subatomic objects in two different directions pending emission or absorption.
Bidirectional, Diametrical, Two-Way
c2 is diametrical . . . two-way.
The direction of light phenomenon if we can even put it that way, regardless of location, is diametrical (or bi-directional). It is "aimed" at the source atom as well as the target atom since when the EM Ropes are tapped into they signal in a polar manner. Light happens in two possible directions: to or from every atom of the Universe. There are always two or more atoms involved in light and gravity. Tapping into a single mediator (our EM Rope, or subatomic object) always influences at least two atoms. Thus the squared factor.
There is no preferred direction of light, like in silly CMBR (Cosmic Microwave Background Radiation) interpretations. Light begins and ends at at least two atoms. And the atom is constantly signalling atoms and being signaled to by atoms via the mediators of light interconnecting all of them.
Einstein's equation is probably the most refined and simple equation in history. It is an all-encompassing, advanced and abstract way to describe an H atom, but it needs some fundamental assumptions and traced objects to understand. Unfortunately most people spit out nonsense about energy converting into matter or mass . . . in other words: concepts converting into concepts. They haven't a clue what they are talking about. There can be no explanation without appealing to something. A theory, explanation, or manifestation is built upon objects: that which have form. These objects perform causal relations with other objects.
At Least Two Atoms . . .
When we talk of this invisible subatomic object that mediates light . . . when acted upon by the atom, two atoms will always be induced to motion. The signalling atom as well as the receiving atom.
At least two atoms are always influenced by a light event. Of course in reality this is multiplied gazillions of times over because these mediators converge and superpose at the atom and in addition there are extraneous mediators of light which begin and end on other atoms, crisscrossing and superposing through the source atom. So if an atom consummates a light event it is possible that gazillions of pairs of atoms are influenced across the Universe. Because if you tap into that mediators it will act in a polar manner, inducing motion along it in opposite directions to where it ends on atoms which could be located at the edge of the Universe. All this is further illustrated in the inverse square law of light.
There is a rich interpretive potential in c squared concept. It also teaches us that light is impossible without two or more atoms.
Why Does a Hydrogen Atom have an Enormous Capacity to Do Work?
Many have wondered about this.
I've written about this here in the past but my thoughts are all scattered. Suffice to say that it is the presence of gazillions upon gazillions of EM Ropes converging from all the other atoms of the Universe into a central fiber bundle, a single object that we call atom (or proton/neutron) and in a single location that gives the H atom its enormous potential to do work, especially in a nuclear reaction.
In a nuclear reaction we have twice the number of these subatomic objects all vying for a single location. It seems that only so many can overlap, crisscross or superpose in a sort of critical thread density. So when two H atoms are forced together to their 'convergence points' an event happens that perhaps taps into every single one of these subatomic objects wherein chemical reactions or atomic electron transitions perhaps less are tapped in an the event that is less volatile. But in a nuclear reaction we might have the action/reaction for an astronomical number of these subatomic objects in a single event.
Two atoms crushed together at a single location means two times the # of these subatomic objects in shock, all acting upon one another in a moment, and this causes a reaction along the EM Ropes which will disturb every surrounding atom since all atoms of the Universe are of course inherently constituted by these subatomic objects that also mediate light as well as gravity.
It would be well to reread famous quotes from Heisenberg and Feynman who sort of flirted with these ideas. In so many words:
"Nature uses only the longest threads to weave her patterns, so each small piece of her fabric reveals the organization of the entire tapestry." ---(Richard Feynaman, The Character of Physical Law)
"Light and matter are both single entities, and the apparent duality arises in the limitations of our language." ---(From "Introductory" in The Physical Principles of the Quantum Theory (1930) as translated by Carl Eckhart and Frank C. Hoyt, p. 10.)
Above we have some simple explanations and descriptions leaving some details out, but there is enormous potential in the H atom or a proton and/or neutron because of its fundamental and indissoluble connection to all other atoms of the Universe which each supply it with an EM Rope so that it can assume its form. If you see an H atom through all the atoms of the Universe then you see its potential.
And this is the 'miracle' of an H atom, as well as the genius hiding in Einstein's equation . Very abstract and lofty but IMPOSSIBLE to even begin to unravel without the assumption that all H atoms are somehow interconnected by an inordinately long subatomic object with unique properties and behaviors. With each successive location the atom assumes, it mysteriously reforms itself out of these subatomic objects, so that it's form remains consistent even as these subatomic objects are always shifting, adjusting, held together, and so on so that:
One the one hand the interior of a proton is a dynamic place, with things [threads] moving around. On the other hand all protons of everywhere and everywhen behave exactly the same way. (Wilczek, The Lightness of Being, p. 44, brackets mine)