[D66] The Conventionality of Simultaneity and the Measurability of the One-Way Speed of Light [revisited]

[René Oudeweg]

The Conventionality of Simultaneity and the Measurability of the One-Way
Speed of Light
A Physical Constraint or a Philosophical Limitation?

René Oudeweg
December 29, 2025






Abstract

The speed of light occupies a foundational role in modern physics,
particularly in the structure of special relativity and the operational
definition of spacetime. While the two-way (round-trip) speed of light 
is experimentally measurable with extraordinary precision, the one-way 
speed of light remains resistant to direct empirical determination. This 
paper examines whether this resistance reflects a merely philosophical 
limitation—arising from conventions of clock synchronization—or a deeper 
physical constraint imposed by the structure of spacetime itself. By 
analyzing the epistemic role of simultaneity, the operational content of 
measurement, and the invariance of physical laws under synchronization 
conventions, this paper argues that the unmeasurability of the one-way 
speed of light is best understood as a structural feature of physical 
theory with philosophical implications, rather than as a deficiency of 
experimental ingenuity.

[...]

ref: http://www.tuxtown.net/pipermail/d66/2024-February/073729.html
ref: http://www.tuxtown.net/pipermail/d66/2021-January/068519.html
ref: http://www.tuxtown.net/pipermail/d66/2021-January/068523.html
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