If the MMX Experiment Showed Interference Fringes, Would It Invalidate Relativity?

The Michelson-Morley Experiment and the Question of Light Speed

The Michelson-Morley (MMX) experiment is a cornerstone in the study of the speed and behavior of light. Its primary aim was to detect the luminiferous ether or aether, a medium thought to carry light waves. However, the experiment famously failed to detect any significant ether wind, leading to the conclusion that the speed of light is constant in all inertial frames of reference. This finding was a crucial piece of evidence supporting the development of Einstein's theory of special relativity.

Despite the MMX results being consistent with relativity, there is a significant detail often overlooked: the MMX only showed that light travels at a constant speed relative to its source. It does not definitively prove that the speed of light is constant across all frames of reference. This distinction is crucial and underscores the need to carefully interpret the results.

Rethinking the MMX Experiment

Imagine, for a moment, if the MMX had shown interference fringes corresponding to an aether wind of 30 km/s. This would have dramatically shifted our understanding of the nature of light. Here's why:

First, it would call into question the prevailing view that light travels through a medium, like the luminiferous ether. This would challenge the very foundation upon which the ether hypothesis was built. In classical physics, objects propagate through a medium at speeds that are influenced by their motion relative to that medium. If the MMX had shown such fringes, it would imply that light's speed is affected by the motion of the observer through the ether, directly contradicting what relativity asserts.

Second, it would raise the possibility that the speed of light is not constant across different frames of reference. This is a significant departure from the principles of relativity, which posits that the speed of light is a universal constant. Such a finding could have led to a reevaluation of the entire framework of special relativity, forcing scientists to explore new models to explain the observed phenomena.

The Role of the Sagnac Experiment

While the MMX experiment focused on the speed of light relative to the source, the Sagnac experiment provides a different perspective, particularly in the context of rotational effects. The Sagnac experiment demonstrates that the interference fringes are influenced by the rotation of the experimental setup. This outcome is consistent with the idea that the observation of light's behavior can be affected by factors beyond just the motion of the observer or the source through the ether.

Interestingly, if the MMX had shown fringes corresponding to an aether wind, it would have indicated that the experimental results were significantly influenced by factors beyond the motion of the Earth through the supposed ether. This could lead to interpretations that the Sagnac effect is not just a side effect of rotation but is also influenced by the motion of the observer or the source relative to the ether.

The Sagnac effect is not just limited to theoretical discussions; it has practical applications in devices such as fiber optic gyroscopes. These devices rely on the fact that light will take a longer path in one direction than the other in a rotating system, leading to a phase difference that can be detected.

Contemporary Perspectives and Implications

Emerging theories and experiments continue to explore the fundamental nature of light and its propagation. While the MMX and the Sagnac experiments are often seen as confirming the principles of relativity, their potential opposite outcomes could broaden the scope of our understanding.

Relativists might propose that the light's speed appears constant due to the relativity of simultaneity and time dilation. However, if the MMX had shown fringes, it would challenge these assumptions and necessitate a deeper reevaluation of these concepts.

The implications of such an outcome are substantial for both theoretical physics and practical applications. It could lead to new models of light's behavior and potentially open up avenues for technological advancements, such as more accurate gyroscopes or even new methods of measuring space and time.