[D66] On the Conceptual and Physical Limitations of Atomic Time and the Case for an Epoch-Free Ephemeris Time

[René Oudeweg]

[Mijn eerste bijdrage aan de serieuze astronomie...]

On the Conceptual and Physical Limitations
of Atomic Time and
the Case for an Epoch-Free Ephemeris Time

René Oudeweg


Abstract

The modern definition of time is rooted in atomic physics, with the SI 
second defined by the hyperfine transition of the cesium-133 atom. While 
this definition provides exceptional precision and operational 
stability, it embeds timekeeping within a local, microscopic, and 
fundamentally non-dynamical phenomenon. This paper argues that
atomic time, despite its technical success, represents a conceptual 
misalignment between the definition of time and the physical role time 
plays in gravitational dynamics, celestial mechanics, and cosmology. We 
revisit Ephemeris Time (ET), a historically important but prematurely 
abandoned dynamical time scale, and argue for its reformulation as an 
epoch-free, relational, and scale-invariant temporal parameter. By
grounding time in large-scale gravitational motion rather than atomic 
resonance, such a reformulation restores conceptual coherence, avoids 
arbitrary constants, and aligns temporal measurement with the structure 
of physical law.

[...]

Conclusion

The replacement of Ephemeris Time by atomic time was a pragmatic 
decision driven by technological constraints, not a resolution of 
foundational questions. While atomic time has proven extraordinarily 
useful, it lacks the dynamical grounding appropriate for a fundamental
definition of time. We argue that an epoch-free Ephemeris Time, defined 
implicitly through gravitational dynamics, offers a conceptually 
coherent and physically meaningful alternative. Reconsidering the 
foundations of timekeeping is not merely an exercise in nostalgia, but a 
necessary step toward aligning temporal measurement with the structure 
of physical law.
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