Time system
In science and technology, time systems are precisely defined time scales . They are primarily based on the earth's rotation or the earth's orbit around the sun, but can differ slightly in the underlying time unit depending on the purpose .
In everyday life, on the other hand, the term is also used for relative systems , the zero point of which is set arbitrarily depending on the application - e.g. for work preparation, operating systems, software or circuits. The time systems of chronology and geology, in turn, are divided into outstanding events in human and earth history .
Time systems in science
In the natural and geosciences, precise time systems play a double role: on the one hand, as the basis for various measurement methods, and a. for measuring the transit time of electromagnetic waves, for position and orbit determinations . On the other hand, they are necessary to describe the orientation of the earth in space, its movement in the solar system and its shape changes.
Each of these systems represents a precisely defined time scale or a related group of such scales to which specific (measured or calculated) times can be related. These scales form a kind of yardstick for measuring time and have
- as a basis a physical- theoretical model that
- must be implemented with sufficient accuracy for the technical application , for example by means of a time signal transmitter .
- The most important of these time systems is that of the universal time ( UT1 and UTC ) and their constantly published difference dUT1 , as well
- its clearly definable connection with atomic and sidereal time
- and GPS time, which is strictly linked to atomic time .
Time systems in technology and everyday life
In the field of technology and everyday life , the above time scales are also used, in particular world time and the respective zone time (CET, CEST, etc.). But the term “time system” also stands for individual, relative time scales that are less sharply defined and adapted to the respective purpose.
The second is the unit of time . In contrast to scientific time systems, however, the zero point of the time scale is often set arbitrarily or adapted to the respective technical process. Examples of such time systems are:
Exact time systems
- Internal time scales of quartz watches (summed cycles of the oscillating quartz) or other clock generators , e.g. for electronic stopwatches or relative time registration
- Interval counters , e.g. for measuring the transit time of electromagnetic waves
- in computer technology the system time , see also PC operating system
Softer systems
In a broader sense, “time systems” are also used to denote measuring or control systems that are not based on strict time scales, such as
- time-based software for service companies or
- fixed time stamps and comparative lap times in sports
- Internal time systems for production and work preparation , for standard times or for time clocks , see also Time and Electronic Organizer
- Time and special clock systems for company working time management , e.g. for core and flexible working hours, for trust-based working hours, etc.
- chronology of events in distributed computer systems by logical clocks .
Chronology and Geology
In chronology and earth sciences - especially geology - the definition of time scales (see also era ) is based on outstanding events such as
- the establishment of empires and dynasties - for example for Rome : " ab urbe condita "
- through the sequence of geological layers ( formations ) and paleontological key fossils , see also stratigraphy .
- For games, especially two-person games, a set of rules to give the players an equal amount of time to think about it.
Time difference and time scale
Continuous time scales as the basis of all time systems can also be used to determine time differences - for example in the form of running times , computing times , planning time requirements and the like. However, time differences can also be measured independently of scales - for example with mechanical or electronic stopwatches , with an oscillator, an hourglass or via a detour via a speed .
See also
literature
- Karl Ramsayer : Geodetic Astronomy . Handbook of Surveying Volume IIa, § 12-14 (astronomical time systems) and § 37-49 (time services, time signals). JB Metzler, Stuttgart 1970
- Ivan I. Mueller : Spherical and Practical Astronomy , Chapter 5 Time Systems to 5.6 Atomic Time Systems . Frederic Ungar Publ., New York 1969
- Wilhelm Westphal : The basics of the physical concept system . 2nd edition, Vieweg-Verlag 1971
- J. Bennett, M. Donahue, N. Schneider, M. Voith: Astronomy - the cosmic perspective . Basic chapter S1.1 (time measurement, astral time systems) and S2 (space and time, relativity). Ed. Harald Lesch, 5th edition (1170 pages), Pearson-Studienverlag, Munich-Boston-Harlow-Sydney-Madrid 2010 [2]
- Bernhard Hofmann-Wellenhof , J. Collins: GPS - Theory and Practice . Chapter 3.3 Time Systems . Springer-Verlag Vienna, New York, 1992
- K. Wagner, T. Bartscher, U. Nowak: Praktische Personalwirtschaft , chapter “Personnel deployment” (time systems p. 120 ff), Springer Fachmedien, Wiesbaden 2002