From GIS to Geocomputation
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From GIS to Geocomputation book
The cosmological event of the Big Bang created the universe and in so doing space-time emerged (some would say “switched on”) as an integral aspect of gravitational fields. Space and time are closely interwoven and should more properly be thought of as a four-dimensional (4D) continuum in which time and space, over short durations, are interchangeable. Nevertheless, we conventionally think of separate one-dimensional (1D) time and three-dimensional (3D) space. The terrestrial space on which we live, the Earth, is at least 4.5 billion years old and has been around for about 40% of the time since time began. Since our earliest prehistory, we have grappled with the problems of accurately measuring time and space. Crude measures of time probably came first given the influences of the regular cycles of the day, tides, the moon, and seasons on our lives as we evolved from forager to agriculturist. With technology, we have produced the atomic clock and the quartz watch. Measuring position, distances, and area were less obvious in the absence of the type of benchmark that the natural cycles provided for time. Early measurements used a range of arbitrary devices-the pace, the pole, the chainand longer distances tended to be equated with the time it took to get to destinations. Much later, the development of accurate clocks was the key to solving the problem of determining longitudinal position when coupled with observations of the sun. Measurement requires numerical systems, and 1D time requires either a linear accumulation (e.g., age) or a cyclical looping (e.g., time of day). Measurement of 3D space requires the development of higher order numerical systems to include geometry and trigonometry. Let us not forget that at the root of algebra and the use of algorithms was the need for precise partitioning of space (land) prescribed by Islamic law on inheritance. Calculus was developed with regard to the changing position (in time) of objects in space as a consequence of the forces acting upon them.