space & time

Matters relating to length and duration in physics and transportation

Travel for space and time

Objects have measures of length, width, and height. Objects also move, that is, travel and so change their position in one or more of the directions of length, width, and height. The relation of the position before and after movement is measured by the difference of length, width, and height, and these differences are called […]

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Proof of three time dimensions

The proof that there are three time dimensions is based on showing that a temporal position is a vector, that is, it has magnitude and direction. That may be shown by considering three orthogonal movements of an object. Let the position of the object be represented by a point (as on a corner) relative to

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Dimensions of dimension

The word dimension has many dimensions of meaning. The basic meaning of a dimension is an independent component of something. For example, color is often considered to have three dimensions: chroma, hue, and value. Mathematically, a dimension is one of a minimal set of independent components of an abstract space. There are many applications of

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Space, time, and spacetime

Operationally, space is that which is measured by a measuring wheel (or surveyor’s wheel) moving along a surface or the equivalent. This is essentially a linear or circumferential measurement, which could also be taken with a rod or rule. Operationally, time is that which is measured by a stop watch or equivalent. This is essentially

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Time and length clocks

An ordinary clock measures time. But what if a clock shows a length instead of a duration? For example, an old-fashioned clock with a face and hands points radially with a constant angular velocity. What if the output came from the circumference instead? A one o’clock reading would be equivalent to 1/12th of the circumference

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Actual and default speeds

The actual speed of a particle or vehicle is the local conversion of duration and distance, that is, local time and space. The potential speed of a particle or vehicle is a characteristic speed for similar particles or vehicles. This characteristic speed is a default speed, to be used if the actual speed is not

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Time at Mach 1

In a sense every speed is a conversion speed, that is, a way to convert time into space and vice versa because multiplying a time interval (duration) times the speed of an object leads to the corresponding space interval (length). In some contexts, i.e., a transportation mode or physical medium, there is a particular speed,

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Directional units

Of the base units of the International System of Units (SI) only two concern movement in a direction: the units of length (metre) and duration (second). The candela measures luminous intensity in a direction without regard for movement. Derived units of movement include speed and velocity (metres per second), force (newton), pressure (pascal), energy (joule),

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Cycles and orbits

The first clocks were the cycles of daily life, notably the diurnal cycle of light and dark. These continued apparently without end and so provided a measure of change, of ceaseless movement and return. Since ancient times the day has been divided into 24 hours, and since medieval times an hour has been divided into

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