Why is the speed of light constant in the vacuum?
The constancy of the speed of light c in the vacuum was the key insight in Einstein’s work on relativity. However this was an assumption, rather than a proof. It is an assumption that has worked well, in that the resulting theory has shown good agreement with many observations. The Michelson-Morley experiment directly tested the idea of Earth moving through a stationary ether, by looking for differences in the speed of light in different directions, and found no evidence to support such a theory. There is no empirical evidence that convincingly shows the speed of light to be variable in-vacuo in the vicinity of Earth. However it is possible that the speed of light is merely locally constant, and different elsewhere in the universe. In our latest paper we show why this might be so.
Fundamental questions about light
There are several perplexing questions about light:
- What is the underlying mechanism that makes the speed of light constant in the vacuum?
- What properties of the universe cause the speed of light to have the value it has?
- If the speed of light is not constant throughout the universe, what would be the mechanisms?
- How does light move through the vacuum?
- The vacuum has properties: electric and magnetic constants. Why, and what causes these?
- How does light behave as both a wave and particle? (Wave-particle duality)
- How does a photon physically take two different paths? (Superposition in interferometers)
- How does entanglement work at the level of the individual photon?
These are questions of fundamental physics, and of cosmology. Consequently there is on-going interest in the speed of light at the foundational level. The difficulty is that neither general relativity nor quantum mechanics can explain why c should be constant, or why it should have the value it does. Neither for that matter does string/M theory. Gaining a better understanding of this has the potential to bridge the particle and cosmology scales of physics.
Is the speed of light really constant? Everywhere? At all times?
There has been ongoing interest in developing theories where c is not constant. These are called variable speed of light (VSL) theories [see paper for more details]. The primary purpose of these is to explore for new physics at deeper levels, with a particular interest in quantum-gravity. For example, it may be that the invariance of c breaks down at very small scales, or for photons of different energy, though such searches have been unsuccessful to date. Another approach is cosmological. If the speed of light was to be variable, it could solve certain problems. Specifically, the horizon, inflation and flatness problems might be resolved if there were a faster c in the early universe, i.e. a time-varying speed of light. There are several other possible applications for a variable speed of light theory in cosmology.
However there is one big problem:
In all existing VSL theories the difficulty is providing reasons for why c should vary with time or geometric scale.
The theories require the speed of light to be different at genesis, and then somehow change slowly or suddenly switch over at some time or event, for reasons unknown. None of the existing VSL theories describe why this should be, nor do they propose underlying mechanics. This is problematic, and contributes to existing VSL theories not being widely accepted.
Cordus theory predicts the speed of light is variable, and attributes it to fabric density
In our paper [apr.v8n3p111] we apply the non-local hidden-variable (Cordus) theory to this problem. It turns out that it is a logical necessity of the theory that the speed of light be variable. The theory also predicts a specific underlying mechanism for this. Our findings are that the speed of light is inversely proportional to fabric density. This is because the discrete fields of the photon interact dynamically with the fabric and therefore consume frequency cycles of the photon. The fabric arises from aggregation of discrete force emissions (fields) from massy particles, which in turn depends on the proximity and spatial distribution of matter.
This theory offers a conceptually simply way to reconcile the refraction of light in both gravitational situations and optical materials: the density of matter affects the fabric density, and hence affects the speed of light. So when light enters a denser medium, say a glass prism, then it encounters an abrupt increase in fabric density, which slows its speed. Likewise light that grazes past a star is subject to a small gradient in the fabric, hence resulting in gravitational bending of the light-path. Furthermore, the theory accommodates the constant speed of light of general relativity, as a special case of a locally constant fabric density. In other words, the fabric density is homogeneous in the vicinity of Earth, so the speed of light is also constant in this locality. However, in a different part of the universe where matter is more sparse, the speed of light is predicted to be faster. Similarly, at earlier time epochs when the universe was more dense, the speed of light would have been slower. This also means that the results disfavour the universal applicability of the cosmological principle of homogeneity and isotropy of the universe.
The originality in this paper is in proposing underlying mechanisms for the speed of light. Uniquely, this theory identifies fabric density as the dependent variable. In contrast, other VSL models propose that c varies with time or some geometric-like scale, but struggle to provide plausible reasons for that dependency.
This theory predicts that the speed of light is inversely proportional to the fabric density, which in turn is related to the proximity of matter. The fabric fills even the vacuum of space, and the density of this fabric is what gives the electric and magnetic constants their values, and sets the speed of light. The speed of light is constant in the vicinity of Earth, because the local fabric density is relatively isotropic. This explanation also accommodates relativistic time dilation, gravitational time dilation, gravitational bending of light, and refraction of light. So the speed of light is a variable that depends on fabric density, hence is an emergent property of the fabric.
The paper is available open access: http://dx.doi.org/10.5539/apr.v8n3p111
The fabric density concept is covered at http://dx.doi.org/10.2174/1874381101306010077.
The corresponding theory of time, which predicts that time speeds up in situations of lower fabric density, is at http://dx.doi.org/10.5539/apr.v5n6p23.
Citation for published paper:
Pons, D. J., Pons, A. D., & Pons, A. J. (2016). Speed of light as an emergent property of the fabric. Applied Physics Research, 8(3): 111-121. http://dx.doi.org/10.5539/apr.v8n3p111
Original work on physics archive (2013) : http://vixra.org/abs/1305.0148