Colloquium: Comparison of Astrophysical and Terrestrial Frequency Standards

TL;DR

This paper compares the stability of natural astrophysical clocks like pulsars and white dwarfs with artificial terrestrial clocks, showing that modern terrestrial clocks outperform natural ones in stability over periods up to two years.

Contribution

The study provides a detailed analysis demonstrating the superior stability of modern terrestrial clocks over natural astrophysical sources within certain timeframes.

Findings

Terrestrial clocks exceed astrophysical sources in stability up to two years.

Beyond two years, both types show similar performance limited by reference timescales.

Modern terrestrial clocks are likely more stable than natural clocks over hundreds of years.

Abstract

We have re-analyzed the stability of pulse arrival times from pulsars and white dwarfs using several analysis tools for measuring the noise characteristics of sampled time and frequency data. We show that the best terrestrial artificial clocks substantially exceed the performance of astronomical sources as time-keepers in terms of accuracy (as defined by cesium primary frequency standards) and stability. This superiority in stability can be directly demonstrated over time periods up to two years, where there is high quality data for both. Beyond 2 years there is a deficiency of data for clock/clock comparisons and both terrestrial and astronomical clocks show equal performance being equally limited by the quality of the reference timescales used to make the comparisons. Nonetheless, we show that detailed accuracy evaluations of modern terrestrial clocks imply that these new clocks are likely to have a stability better than any astronomical source up to comparison times of at least hundreds of years. This article is intended to provide a correct appreciation of the relative merits of natural and artificial clocks. The use of natural clocks as tests of physics under the most extreme conditions is entirely appropriate; however, the contention that these natural clocks, particularly white dwarfs, can compete as timekeepers against devices constructed by mankind is shown to be doubtful.