We explain what a magnitude is and the characteristics of scalar, vector and tensor magnitudes.
What is a magnitude?
By the term magnitude, in general, we should simply understand the measure of something. An object, a living being, a force of nature, all have measurable and quantifiable dimensions and features, which can be expressed through mathematical language, that is, magnitudes.
The word magnitude comes from the Latin magnitudo, translatable as "greatness", since in principle this term applies to the dimensions of physical bodies, that is, concrete objects, each inscribed in a system of measurement or measurement system.
The length, height, depth, for example, are dimensions expressible in units of measurement like the meter, the kilometer or the centimeter. On the other hand, values such as the goodness or cruelty of a person cannot be objectively measured, and therefore do not constitute magnitudes.
Thus, the magnitudes are subject of study of the physical. Each system of units and measurements available proposes its own standard based on which to carry out its measurements: the International system (SI), for example, proposes, as we said before, the meter as the unit of measurement of length. Now, the magnitudes can be of three types, depending on their nature:
- Scalar quantities, when they can be measured and expressed totally through a number, without it being necessary to explain any other sense, such as direction. Its values can be independent of the observer, dependent on the position of the object, or the movement of the observer. Examples of these are: length, temperature, the mass, the volume, the weather, the electric charge, etc.
- Vector quantities, for which a specific number is not enough to be measured, since they have an orientation or a sense that must be expressed through a vector: a line segment with direction. Such is the case of speed, force, the acceleration, the light intensity or the electric field, for example.
- Tensor magnitudes, those that respond to representations through Models changing, depending on the state of movement or the orientation of the observer.
As we have seen, every magnitude is necessarily expressed as a set of mathematical units framed in a logical system. Some of them are conventional, arbitrary units, such as the meter, the kilogram or the second, while others are necessarily understood from combinations of conventional units, such as the Newton (kg. M / s2) or the Joule (kg. m2 / s2).
However, the term magnitude can also be used in a way figurative, to refer to the gravity or importance of something, as occurs in phrases such as "The magnitude of events cannot be underestimated" or "the magnitude of my love is immeasurable", meaning in those cases that it is something very big , that is, of proportions -figuratively- difficult to measure in the big way.