The concept of emptiness in spite of its apparent simplicity, is very complex and multi-valued.
The answer to the question, what is emptiness, is determined by the context in which it is placed.
At first glance, everything is simple: emptiness - it is a complete lack of ... what? For example, if a coffee pot was left over coffee, they say that the bank is empty. But this is not so: the bank is filled with air. You can seal the jar and pump the air out of it, but even then it will not be completely empty. It will continue to act in the field - the gravitational, magnetic, and they, though are not a substance is a form of existence of matter.
This situation raises questions about the fundamental possibility of the existence of the void.
"Nature abhors a vacuum" - this sayingAristotle centuries been an axiom of science. One of his evidence was considered the principle of operation of the pump when the piston rises, it is formed under vacuum. Nature seeks to immediately fill it with something, so for the piston rushes water.
To a certain extent this principle worked. But in 1640 the Duke of Tuscany wanted to decorate the garden of his palace, located on a hill, a fountain. The water is supposed to pump from the pond, which was located at the foot of the hill. Despite the best efforts of the masters, the water from the fountain pipe and did not go. No one could understand what was happening: because "fear of emptiness" should drive the water to any height!
Three years later, the court mathematician E.Torricelli explained the reason for the failure with the help of well-known experience: in a cup of mercury upset the tube, which is also mercury. "Live Metal" is slightly lowered, forming a pillar, and above it - emptiness, dubbed Torricellian.
This experience was not only openlyatmospheric pressure, but also refuted the idea of a mythical "fear of emptiness." However, Torricellian emptiness, too, was not completely empty, it was filled with mercury vapor, but for its time it was enough, and this: void may well exist in nature.
Void in terms of different sciences
Given the ambiguity of the concept of emptiness, every science puts in a word its meaning, and there are even different terms to describe the void.
One of these terms - a vacuum, which is translated fromLatin means "empty". So we call a space where there is no substance, but there are fields. From the physical vacuum should be distinguished technical vacuum - a space filled with highly rarefied gas. This happens, for example, cathode ray tubes, vacuum cleaner or vacuum packed for products.
In astronomy, the term "Void", which is alsois translated from English as "emptiness", designate a space where no stars, no galaxies. But such a space is not completely empty: it can be protogalactic clouds and dark matter.
There is a concept of emptiness and in computer science. In another way it is called a null pointer, and is a variable that does not refer to any object.