The first models of the world.
Despite the high level of astronomical information of the peoples of the ancient East, their views on the structure of the world were limited to direct visual sensations. Therefore, in Babylon, views have developed that the Earth has the appearance of a convex island surrounded by the ocean. Inside the Earth, as if there is a “kingdom of the dead.” The sky is a solid dome resting on the earth’s surface and separating the “lower waters” (the ocean flowing around the earth’s island) from the “upper” (rain) waters. Celestial bodies are attached to this dome, as if gods live above the sky. The sun rises in the morning, leaving the eastern gate, and sets through the western gate, and at night it moves underground.
According to the ideas of the ancient Egyptians, the Universe looks like a large valley, stretched from north to south, in the center of it is Egypt. The sky was likened to a large iron roof, which is supported on pillars, on it in the form of lamps suspended stars.
In ancient China, there was a view according to which the Earth had the shape of a flat rectangle, over which a round convex sky was supported on poles. The enraged dragon seemed to bend the central pillar, as a result of which the Earth bent to the east. Therefore, all rivers in China flow east. The sky leaned to the west, so all the celestial bodies move from east to west.
And only in the Greek colonies on the western shores of Asia Minor (Ionia), in the south of Italy and in Sicily in the fourth century BC did the rapid development of science, in particular philosophy, begin as a doctrine of nature. It is here that the simple contemplation of natural phenomena and their naive interpretation is replaced by attempts to scientifically explain these phenomena, to unravel their true causes.
One of the most prominent ancient Greek thinkers was Heraclitus of Ephesus (c. 530 – 470 BC). It belongs to him the words: “The world, one of all, was not created by any of the gods and by none of the people, but was, is and will always be a living fire, naturally igniting and naturally extinguishing …” Then Pythagoras of Samos (c. 580 – 500 BC) suggested that the Earth, like other celestial bodies, has the shape of a ball. The universe seemed to Pythagoras in the form of concentric, transparent crystal spheres embedded in each other, to which planets were attached. The Earth was placed in the center of the world in this model, the spheres of the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn revolved around it. Next to all was the sphere of fixed stars.
The first theory of the structure of the world, explaining the direct and backward movement of the planets, was created by the Greek philosopher Eudoxus of Cnidus (c. 408 – 355 BC). He suggested that each planet has not one, but several spheres bonded to each other. One of them makes one revolution per day around the axis of the celestial sphere in the direction from east to west. The time of revolution of the other (in the opposite direction) was assumed to be equal to the period of revolution of the planet. This explains the movement of the planet along the ecliptic. It was assumed that the axis of the second sphere is inclined to the axis of the first at a certain angle. The combination with these two areas made it possible to explain the backward movement with respect to the ecliptic. All the features of the movement of the sun and moon were explained using three spheres. Eudox placed the stars on one sphere, containing all the others. Thus, all the visible movement of the heavenly bodies Eudoxus reduced to the rotation of 27 spheres.
It is worth recalling that the philosopher Plato expressed the idea of a uniform, circular, absolutely correct movement of celestial bodies. He suggested that the Earth is in the center of the world, that the Moon, the Sun revolves around it, then the morning star Venus, the star of Hermes, the stars of Ares, Zeus and Kronos. Plato first encountered the names of the planets by the name of the gods, completely coinciding with the Babylonian ones. Plato first formulated the problem for mathematicians: to find, by means of which uniform and regular circular motions one can “save the phenomena represented by the planets.” In other words, Plato set the task to build a geometric model of the world, in the center of which, of course, the Earth should have been.
The improvement of the world system of Eudoxus was taken by the student of Plato Aristotle (384 – 322 BC). Since the views of this outstanding philosopher, the encyclopedist, have reigned supreme in physics and astronomy for almost two thousand years, I will dwell on them in more detail.
Aristotle, following the philosopher Empedocles (c. 490-430 BC), suggested the existence of four “elements”: earth, water, air and fire, from the mixture of which all the bodies found on Earth seem to have originated. According to Aristotle, the elements, water and earth naturally tend to move to the center of the world (“down”), while fire and air move “up” to the periphery and the faster, the closer they are to their “natural” place. Therefore, in the center of the world is the Earth, above it are water, air and fire. According to Aristotle, the Universe is limited in space, although its movement is eternal, has no end or beginning.