By reason of the application of the Lorentz Factor [(1 - (v squared / c squared)) raised to the power of 1/2] in the denominator of equations, luminal and other comparable energy propagations take on one and the same velocity. This is the relativity-effect (better, comparative effect) between v of objects, compared to c of the speed of light. That is, it is presupposed here that c is the object of comparison for determining the speed effect of velocity difference across a duration.
It is against the criterion-velocity itself c that c becomes unsurpassable! Hence, I am of the opinion that the supposed source-independence is nothing but an effect of OUR APPARATUS-WISE OBSERVATION LIMIT AND OUR FIXING OF THE CRITERION OF OBSERVATION AS THE OBSERVED VELOCITY OF LIGHT.
In this circumstance, it is useless to claim that (1) luminal and some other energy propagations with velocity c are source-independent, and (2) these wavicles have zero rest mass, since the supposed source-independence have not been proved theoretically or experimentally without using c cas the criterion velocity. The supposed source-independence is merely an effect of c-based comparison.
Against this background, it is possible to be assured that photons and other similar c-wavicles are extended particles -- varying their size throughout the course of motion in the spiral manner. Hence the acceptability of the term 'wavicle'. Moreover, each mathematical point of the spiral motion is to be conceived not as two-, but as three-dimensional, and any point of motion added to it justifies its fourth dimension. Let us call motion as change.
These four dimensions are measuremental, hence the terms 'space' (three-dimensional) and 'time' (one-dimensional). This is also an argument countering the opinion that in physics and cosmology (and other sciences) time is not attested!
The measurements of the 3-space and measurements of the 1-time are not in the wavicles and in the things being measured. The measurements are the cognitive characteristics of the measurements.
IN FACT, THE EXTENSION OF THE WAVICLE OR OTHER OBJECTS IS BEING MEASURED AND TERMED 'SPACE', AND THE CHANGE OF THE WAVICLE OR OTHER OBJECTS IS BEING MEASURED AND TERMED 'TIME'. Hence, the physically out-there-to-find characteristics of the wavicles and objects are EXTENSION AND CHANGE.
Extension is the quality of all existing objects by which they have parts. This is not space. Change is the quality by which they have motion, i.e., impact generation on other similar wavicles and/or objects. This is not time. Nothing has space and time; nothing is in space and time. Everything is in Extension-Change.
Any wavicle or other object existing in Extension-Change is nothing but impact generation by physically existent parts. This is what we term CAUSATION. CAUSALITY is the relation of parts of physical existents by which some are termed cause/s and the others are termed effect/s. IN FACT, THE FIRST ASPECT OF THE PHYSICALLY ACTIVE PARTS, WHICH BEGINS THE IMPACT, IS THE CAUSE; AND THE SECOND ASPECT IS THE CAUSE. Cause and effect are, together, one unit of continuous process.
Since energy wavicles are extended, they have parts. Hence, there can be other, more minute, parts of physical objects, which can define superluminal velocities. Here, the criterion of measurement of velocity cannot be c. That is all...! Hence, superluminal velocities are a must by reason of the very meaning of physical existence.
THE NOTION OF PHYSICAL EXISTENCE ('TO BE') IS COMPLELTEY EXHAUSTED BY THE NOTIONS OF EXTENSION AND CHANGE. Hence, I call Extension and Change as the highest physical-ontological Categories. A metaphysics (physical ontology) of the cosmos is thus feasible. I have been constructing one such. My book-length publications have been efforts in this direction.
I invite your contributions by way of critiques and comments -- not ferocious, but friendly, because I do not claim that I am the last word in any science, including philosophy of physics.
Bibliography
(1) Gravitational Coalescence Paradox and Cosmogenetic Causality in Quantum Astrophysical Cosmology, 647 pp., Berlin, 2018.
(2) Physics without Metaphysics? Categories of Second Generation Scientific Ontology, 386 pp., Frankfurt, 2015.
(3) Causal Ubiquity in Quantum Physics: A Superluminal and Local-Causal Physical Ontology, 361 pp., Frankfurt, 2014.
(4) Essential Cosmology and Philosophy for All: Gravitational Coalescence Cosmology, 92 pp., KDP Amazon, 2022, 2nd Edition.
(5) Essenzielle Kosmologie und Philosophie für alle: Gravitational-Koaleszenz-Kosmologie, 104 pp., KDP Amazon, 2022, 1st Edition.