Density, from the Latin densĭtas, is the proper characteristic of dense. This adjective, in turn, refers to something that has a large amount of mass compared to its volume; that it is bushy or solid; that it has an important level of content or is very deep in a reduced dimension; or that it is undefined and unclear.
In the field of chemistry and physics, density is the magnitude that reflects the link between the mass of a body and its volume. In the International System, the unit of density is the kilogram per cubic meter (known by the symbol kg/m3).
A kilogram of bronze, for example, will take up much less space than a kilogram of feathers. This is explained from density: bronze is denser (has more mass in less volume) than feathers. Density differences allow heavy but small objects and light but very large objects to exist.
Just as the relationship between mass and volume of a body allows us to obtain the density of an object, demography appeals to a similar logic to speak of population density. In this case, the magnitude is calculated from the number of inhabitants living in the same surface unit. If a city has 20,000 people who are distributed in a territory of 2 square kilometers, its population density will be 10,000 inhabitants per km2.
Optical density, on the other hand, refers to the level of absorption of light. In photography, the concept of density is linked to the darkening of an image according to the amount of light to which it has been exposed.
In computing, density indicates the number of bytes that can be deposited in a memory storage system.
Population density and environmental imbalances
A concept deeply linked to this concept is that of population density, which refers to demography, that is, the number of individuals that inhabit a given territory.
In order for any species, whether plant or animal, to develop in a given habitat in the recommended and equitable manner with the environment, it is necessary that there be a similar relationship between resources present in the space and their use; If the number of individuals exceeds the amount of resources to distribute among all, we speak of an environmental imbalance, where life in all its aspects is in danger.
When this anomaly occurs, it usually happens that a series of changes are naturally carried out in the populations to avoid the excessive increase of the community and ensure the survival of the species. Some of these transformations are:
* Slow development (when space and food are scarce, individuals begin to develop slowly and therefore, reproductive processes are delayed, bringing balance to the community);
* Low fertility (due to the weakening of the mothers, due to poor nutrition, the number of offspring decreases and they are more prone to mortality);
* Decrease in the size of individuals (scarcity in turn causes individuals to grow and weigh less);
* Emigration (if possible, part of the population moves to other regions in search of a better quality of life);
* Disappearance of the population (when the damage caused in the natural environment is excessive, the extinction of the species in said territory can be generated. It can occur gradually or abruptly, as if it were an epidemic).
It is worth mentioning that in the case of human beings, due to the fact that there are very few birth control measures that exist and that, thanks to scientific advances, the mortality rate takes place at a later age, we have come to overpopulate the planet. If comprehensive measures to equalize the distribution of resources and at the same time control the level of births did not take place, it would be impossible not only to end world hunger, but also to ensure a prosperous life for the species in any corner of the planet.