Related papers: Time in the 10,000-Year Clock
Solar quasi-biennial oscillations with period range 0.6 to 4 years, are prominent in records of solar activity. Here we show that the 1.6 year quasi-biennial oscillation in solar activity has the exceptional feature of phase inversion…
Optical clocks are not only powerful tools for prime fundamental research, but are also deemed for the re-definition of the SI base unit second as they now surpass the performance of caesium atomic clocks in both accuracy and stability by…
Ultra-precise optical clocks in space will allow new studies in fundamental physics and astronomy. Within an European Space Agency (ESA) program, the Space Optical Clocks (SOC) project aims to install and to operate an optical lattice clock…
The level of solar magnetic activity, as exemplified by the number of sunspots and by energetic events in the corona, varies on a wide range of time scales. Most prominent is the 11-year solar cycle, which is significantly modulated on…
We consider a clock 'paradox' framework where an observer leaves an inertial frame, is accelerated and after an arbitrary trip comes back. We discuss a simple equation that gives, in the 1+1 dimensional case, an explicit relation between…
In this paper we deal analytically with a version of the so called clock paradox in which the moving clock performs a circular motion of constant radius. The rest clock is denoted as (1), the rotating clock is (2), the inertial frame in…
We present a transportable optical clock (TOC) with $^{87}$Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of ${7.4 \times 10^{-17}}$ which is currently limited by the statistics of…
Being able to measure time, whether directly or indirectly, is a significant advantage for an organism. It permits it to predict regular events, and prepare for them on time. Thus, clocks are ubiquitous in biology. In the present paper, we…
Among the first devices used to measure the time we find the sundials and the water-clocks, as told by Vitruvius in his book on the Architecture. The sundials work because of the shadows cast by a rod or pole, the gnomon, on their…
We present analog clocks fitted to the Mars solar day. These clocks use the standard Earth-based second of the International System of Units (SI) as their operational unit of time, unlike current practice for Mars timekeeping. We discuss…
There are many different types of time keeping devices. We use the phrase ticking clock to describe those which -- simply put -- "tick" at approximately regular intervals. Various important results have been derived for ticking clocks, and…
Improvements in atom-light coherence are foundational to progress in quantum information science, quantum optics, and precision metrology. Optical atomic clocks require local oscillators with exceptional optical coherence due to the…
Long-term modulation of solar differential rotation was studied with data from Mt. Wilson and our original observations during Solar Cycles 16 through 23. The results are: i) The global B-value (i.e. latitudinal gradient of differential…
This paper investigates postmortem timestamp reconstruction in environmental monitoring networks. In the absence of a time-synchronization protocol, these networks use multiple pairs of (local, global) timestamps to retroactively estimate…
Circadian clocks are the central timekeepers of life, allowing cells to anticipate changes between day and night. Experiments in recent years have revealed that circadian clocks can be highly stable, raising the question how reliably they…
Earth's analemma is the lopsided figure eight marked out over a year by the position of the Sun in the sky observed at the same clock time each day. It shows how solar time deviates from clock time. The analemma's shape results from the…
In the next decade or two, extremely accurate tests of general relativity under extreme conditions are expected from gravitational wave observations of binary black hole mergers with a wide range of mass ratios. In addition, major…
We report an optical lattice clock with a total systematic uncertainty of $8.1 \times 10^{-19}$ in fractional frequency units, representing the lowest uncertainty of any clock to date. The clock relies on interrogating the ultra-narrow…
Some 50~years ago, physicists, and after them the entire world, started to found their time reference on atomic properties instead of motions of the Earth that have been in use since the origin. Far from being an arrival point, this…
The Sun shows a wide range of temporal variations, from a few seconds to decades and even centuries, broadly classified into two classes short-term and Long-term. The solar dynamo mechanism is believed to be responsible for these global…