A new theory of Space and Time by Jim Redgewell

 

Why Is the Speed of Light Always Constant for Every Observer?

One of the most surprising and fundamental discoveries in modern physics is that the speed of light in a vacuum is always constant—about 299,792,458 meters per second—for every observer, regardless of their motion or the motion of the source of the light. This fact is a cornerstone of Einstein's special theory of relativity and has profound implications for how we understand space, time, and the very nature of reality.

A Classical Expectation—and Its Failure

In Newtonian physics, speeds add. If you're on a train moving at 50 km/h and you throw a ball forward at 20 km/h, someone on the platform sees the ball moving at 70 km/h. Scientists in the 19th century assumed light worked the same way. They believed light traveled through a medium called the "luminiferous ether," and that an observer's motion relative to this ether would affect the observed speed of light.

But this assumption failed spectacularly. The Michelson-Morley experiment (1887) tried to measure Earth's motion through the ether by detecting changes in the speed of light in different directions. They found no such difference. No matter how they moved the apparatus or when they measured it, the speed of light remained constant.

Einstein's Radical Postulate

Albert Einstein, in 1905, took this experimental result and made it a foundational postulate:

The speed of light in vacuum is the same for all observers, regardless of their relative motion or the motion of the light source.

This idea led to the development of special relativity, which introduced revolutionary concepts like time dilation, length contraction, and the relativity of simultaneity. These are not strange artifacts—they are necessary consequences of preserving the constancy of light speed.

Spacetime and the Geometry of Light

In special relativity, space and time are unified into a four-dimensional construct called spacetime. The speed of light is not just a speed—it's a fundamental feature of the geometry of this spacetime. Light always travels along paths where the spacetime interval is zero (called "null paths"), and this structure is the same for all observers. This is why light always moves at the same speed in vacuum, no matter how fast you're moving.

A New Perspective: Could the Vacuum Itself Be Variable?

Here's where new ideas emerge. The speed of light in vacuum depends on two physical constants: the vacuum permittivity (ε₀) and permeability (μ₀):

If these properties of the vacuum could be altered—say, by intense fields, exotic matter, or a non-uniform structure of spacetime—then the local speed of light could, in principle, change. This would mean the "vacuum" isn’t truly empty, but a medium with physical properties that can vary. This line of thought reopens the door to a modern kind of "ether": not a static background, but a dynamic, physical field like the Higgs field.

Rethinking Fermions and Motion: A Tugboat Model

Photons interact with the vacuum through electromagnetic induction—moving not through empty space, but through the structure of space defined by its permittivity and permeability. This interaction gives them the character of both a wave and a localized energy packet.

Fermions, on the other hand, obtain mass via the Higgs field, which prevents them from moving at the speed of light. But what if fermions, like photons, are also driven by an interaction with the vacuum? Imagine that a fermion is "towed" through space by a quantum impulse—like a tugboat pulling a massive ship.

From Einstein’s equation:

We see that a particle’s total energy has two parts: the mass-energy term (mc²), and the momentum-related energy (pc). In this analogy, mc² is the "anchoring mass" from the Higgs field, while pc might correspond to the energy from a field-mediated impulse—akin to the photon's energy.

Additionally, de Broglie's relationship:

links this momentum to the wave-like nature of matter. The tugging impulse could resonate with the fermion’s own wave structure, guiding its motion like a pilot wave. This coupling may explain the duality of mass-bearing particles—moving through space not as isolated dots, but as resonant systems between mass and wave.

Implications for Faster-Than-Light Travel

If the local speed of light could be increased in a region of space, then an object could travel faster than the current universal speed limit (c), while still being under the new, locally-redefined limit. This would preserve the structure of relativity locally, while potentially allowing faster-than-light effects globally. It's a speculative but fascinating concept that might redefine how we view space, time, and motion.

Conclusion

The constancy of the speed of light is not just a curious quirk—it’s a window into the deep structure of the universe. But as we probe deeper into the nature of fields, vacuum, and the fabric of spacetime, we might find that what we call "constants" are not quite as constant as we thought. And in that flexibility may lie the future of physics—and perhaps even interstellar travel.

Meanwhile, the analogy of mass-bearing particles being pulled forward by wave-like field impulses offers a fresh way to conceptualize quantum motion. It provides an intuitive bridge between quantum mechanics, field theory, and relativity—and perhaps a new direction for theoretical physics.