Concepts of space-time and measurement units

Abstract

With the rapid development of time-space measurement techniques, such as atomic clocks, astronomy satellites, telescopes, and VLBI, SLR, LLR, GNSS et al, the and temporal scales to measure is expanding, and the measurement precision is also continuously improved. Space measurement uncertainty is nearly of the order of 1E-12, and the timing uncertainty is even better than that of 1E-15. The range of precision measurement is from the near Earth, the Earth-Moon system, extended to the solar system, even to the cosmological scales. Then there must be accurate theoretical models to be suitable with the highly precise measurements. Now, general relativity and quantum mechanics are the theoretical basis of large-scale measurement and precision timing. Time, space, gravitation, and light are the basic issues of science and technology. The basic concepts of them are introduced. The basic rules of metric and the units of and are discussed. The basic ideas are as follows: a) Light and electromagnetic waves are the basic objects of measurements. All substances have characteristics of energy absorption and releasing (radiation). The absorption and releasing of energy presents the quantum properties. The propagation of radiation energy in is of the wave form. b) The (intrinsic) frequency, which is observed by the observer with the same temporal state of the source, is determined by the physical attribute of light emitter (or the source), while the observed of light (for any observer) is depended not only to the source, but also to the temporal states (space positions and relative speeds) of the observer and the source. c) The speed of light propagation is affected by the medium in space-time, but independent to the source. d) A special null-like energy should be carefully chosen as a reference for the measurement of space-time. The unit of is defined by the adopted proper frequency value of the null-like energy and the unit of length is done by the adopted proper wavelength. e) The spatial distance and time interval of two are associated with the observer, and they are not invariables. Or in other words, the observed results of and length observed by different observers are different for the same events. There is no absolute and space. Different observer has different and space. f) There exists interval between the two universal events which is nothing to do with the observers. The time interval and space distance” are just the different perception forms of space-time interval. For the metric of space-time, a coordinate reference system must be constructed, in which a special observer's reference frame is chosen and is expanded in some rules to the outer in order to cover a certain range of space-time. Generally, different coordinates have different units of and time.