He was born in Abderea, Greece, and dissapeared around 370 BC.
Democritus is more known by his Atomic Theory but also he was an excellent geometrician, very little knows itself of his life, we know that Leucippus was his professor.
He belongs to the doctrinal line of thinkers who were born with Thales de Mileto. This school as well as Pythagorean and the eleática, that represents greatest of the previous thought, attributes great importance to him to the mathematician.
The atomists thought different from the eleatas, because while these did not accept the movement like reality, but like phenomenon,
Leucipo and Democritus they start off of which the movement exists in himself. Democritus puts like fundamental realities to atoms and the emptiness, or as they would say the eleatas, to the being and not being (We remember that the word etimológicamente atom in Greek, means indivisible, which at the moment we know that he is not thus).
Note in Democritus a effort to replace the notion of quality by the one of amount.
One knows that it wrote several treaties of Geometry and Astronomy, but unfortunately all lost ones. One thinks that it wrote on Theory of the Numbers. It found the B*h/3 formula that expresses the volume of a pyramid. Also it demonstrated that this formula can be applied to calculate the volume of a cone.
The two theorems are also attributed to him following:
1º "the volume of a cone is equal to a third of the volume of a cylinder of equal base and height"
2º "the volume of a pyramid is a third of the volume of the prism of equal base and height"
A problem very different from all the sight until now worried also to the schools of Jonia and the Magna Greece: the one of the nature of the light. Democritus sustains the theory of the emission according to which the vision is caused by the particle projection that comes from the same objects. He is not this more than the principle of the long row of theories that are of the light in the history of sciences. The theory of the emission is custom to attribute it to Newton, who exposed many centuries later.
It is important to make notice that, from his first steps, rational science tries to look for an explanation of all the natural phenomena starting off of a small number of basic principles.
This attempt did not let influence favorably in the later development of all sciences.
Thus we have seen that, in the beginning, for many of these philosophers a arithmetic-geometric principle prevailed to explain many facts. Thus, Democritus until the flavor of the things explained it under this aspect. In effect, he attributed special a geometric form to him to the things to be pleasant such-and-such "": the candy sensation had to the spherical formof the substance that forms to the body that produces it; the bitter thing, had to the smooth and cleared form, and bitter or the acid thing to angular and the acute thing. An analogous origin and interpretation it attributed to the phenomena of the tact.
Finally we will say on the binomial Leucipo-Democritus that thought that the emptiness also existed not only in the world in which we lived, but much more there, in the infinite spaces of the Cosmos.
They believed in the existence of an infinite number of "worlds" all compounds of an infinite number of atoms.
Elements of nuclear physics (a little history)
Five centuries before Christ, the Greek philosophers were asked if the matter could be divided indefinitely or if it would arrive at a point that such particles were indivisible. It is thus, as Democritus formulates the theory that the matter is made up of indivisible particles, to which called atoms (of Greek the atomos, indivisible).
In 1803 English chemistry John Dalton proposes a new theory on the constitution of the matter. According to Dalton all the matter could be divided in two great groups: the elements and the compounds. The elements would be constituted by fundamental units, that in honor to Democritus, Dalton denominated atoms.
The compounds would be constituted of molecules, whose structure comes given by the union from atoms in defined and constant proportions. The theory of Dalton continued considering the fact that the atoms were indivisible particles.
Towards end of century XIX, it was discovered that the atoms are not indivisible, because they are made up of several types of elementary particles. First in being discovered it was the electron in 1897 by Sir investigator Joseph Thomson, who received the Nobel prize de Fi'sica in 1906. Later, Hantaro Nagaoka (1865-1950) during his works made in Tokyo, proposes his theory according to which electrons would turn in orbits around center body loaded positively, like the planets around the Sun Nowadays we know that the positive charge of the atom is concentrated in a dense very small nucleus, in whose around turn electrons.
The nucleus of the atom is discovered thanks to the works made in the University of Manchester, under the direction of Ernest Rutherford between years 1909 of 1911. The used experiment consisted of directing a particle beam of certain energy against a thin metallic plate, of the probabilities that such barrier turned aside the trajectory of particles, was deduced the electrical trimming to the interior of atoms.
Chemistry and British physicist, worked with effectiveness to be able to the union between the old atomic concept of chemical element and the hypotheses, that Serbian to develop the atomic theory on which modern physical science is based. It was born the 6 of September of 1766, in Eaglesfield, (Cumbria). Educated in a cuáquera school of his native city, she was an authentic self-taught person. It had to stay humbly like teacher from the 12 years. In 1781 it was transferred to Kendal, where it directed to a school with his cousin and his older brother. One went to Manchester in 1793 and there it passed the rest of his life like professor, first in the New College and later like private tutor.
In 1787 Dalton a series of meteorological studies began that continued during 57 years, accumulating 200,000 observations and measures on the climate in the area of Manchester. The interest of Dalton by meteorology took to him to study a great number of phenomena as well as the instruments necessary to measure them.
It was first in proving the theory that rain takes place by a diminution of the temperature, and not by a change of atmospheric pressure.
Nevertheless, to the first work of Dalton, meteorological Observations and tests (1793), little attention was lent to him very.
In 1794 it presented/displayed in the Philosophical and Literary Society of Manchester a test on the color blindness, a defect that he himself suffered; the test was the first description of this phenomenon, denominated thus by the own Dalton.
Its more important contribution to science was its theory that the matter is made up of atoms of different masses that are combined in simple proportions to form compound. This theory, that Dalton formulated for the first time in 1803, is the angular stone of modern physical science. In 1808 its work was published New system of chemical philosophy, (work which I publish myself in two parts, first in 1.808 and second in 1.810) that included the atomic masses of several elements known in relation to the mass of hydrogen.
Their masses were not totally precise but they constitute the base of the modern periodic classification of the elements.
Dalton arrived at its atomic theory through the study of the physical properties of the atmospheric air and other gases. In the course of the investigation law of Dalton of the partial pressures discovered the well-known law like =, according to which, the pressure exerted by a gas mixture is equal to the sum of it partial pressures that one of gases would exert each if single he occupied the total volume of the mixture.
Dalton had a strong initiative and rich imagination, particularly for the mechanical models and mental images, but most remarkable it was his extraordinary physical intuition that took to important conclusions, in spite of being only a coarse experimenter, as his contemporary Humphry Davy called to him.
Dalton was chosen member of the Real Society of London in 1822 and four years later the gold medal of this society was granted to him. 1830 Dalton one became one of the eight foreign partners of the French Academy of Sciences. It died the 27 of July of 1844 in Manchester.
Let us return to the growth of the atomic theory of chemistry. The treaty of Dalton, New system of chemical philosophy, was published in two parts, 1808 and 1810. We will abstract of this work and some of its writings the main principles that reflect the fundamental ideas of their conceptual scheme.
a) The matter consists of indivisible atoms. * The matter, although divisible in an
extreme degree, is not, nevertheless, infinitely divisible. This is, must have a point, beyond as we cannot go in the division of the matter. The existence of these last particles of the matter cannot as soon as to put itself in doubt, although probably they are so extremely small that they cannot even be appraised nor with microscopic devices. I have chosen the word atom to represent these last particles...
b) The atoms are invariable. The atoms of the different elements * never can be transformed into the others by no power that we pruned to control, as the failure of the alchemy had declared clearly. Continuous
tests had demonstrated that the transmutación of elements was impossible obtained of a similar way to the deduction of an impotence postulate the law of conservation of the energy from the failure of the obtaining of the perpetual moving body.
c) The compounds are formed by molecules. The chemical compounds are formed by the atom
combination of two or more elements in composed atoms, or molecules that are as now we called to the smallest particles of a compound.
Turin, 1776-1856. Chemistry and Italian physicist. He was university professor of physics in the
University of Turin during two períodos(1820-1822 and 1834-1850). In its writings published by the Journal de Physique, the way to determine the relative masses of molecules and the proportions in which these combine establishes the famous hypothesis that volumes of equal gases to the same conditions of temperature and pressure, contain equal number of molecules. It determined that simple gases as the hydrogen and oxygen are diatómicos (H2, O2) and assignedthe formula (HÒ) for the water. The laws of Avogadro solved the conflict between the atomic theory of Dalton and the experiences of Gay-Lussac. The number of particles in "mol" of substance was denominated constant or number of Avogadro in its honor.
