The Speed of Light and Its Limits. Quantum Entanglement as Empirical Evidence

The speed of light, c, is the best-confirmed constant in physics. Within Special Relativity, it defines the causal structure of spacetime and no experiment has ever recorded an object exceeding it. This paper does not dispute any of that.

What this paper argues is that quantum entanglement constitutes indirect but serious evidence that the extrapolation of c to a universal limit across all layers of physical reality is not forced by the data. c is the fundamental limit of relativistic spacetime. Whether it is also the limit of whatever substrate gives rise to that spacetime is a question the experiments force us to take seriously, and that current physics leaves genuinely open.

Bell-test experiments, confirmed from Aspect (1982) to the Large Hadron Collider (2023), show that entangled correlations cannot be explained by any locally factorizable model. Something produces those correlations without any mechanism that respects c. The no-communication theorem shows that this cannot be exploited for signalling, today, within the current framework. It does not show that c governs the mechanism that produces the correlations. Those are different claims, and conflating them has allowed a mathematical result about signal statistics to carry unwarranted ontological weight.

This is a conceptual and philosophical analysis grounded in experimental results. It does not propose a new theory. It argues that the evidence we already have is sufficient to challenge the extrapolation that treats c as an absolute limit across all layers of physical reality. That extrapolation is not forced by the data. It is a theoretical choice, and a contestable one.