2. Ideas Of Philosophers And Astronomers Of The Middle Ages About The Universe. (II Century - XVII Century) - Aether

2. Ideas of philosophers and astronomers of the Middle Ages about the universe. (II century – XVII century)

Ideas of philosophers and astronomers of the Middle Ages about the universe. (II century – XVII century)

In the Middle Ages, scientists and astronomers generally adhered to the provisions developed by Aristotle and Ptolemy. The Catholic Church supported these views and officially recognized the initial views of philosophers on the foundations of the universe, adopting a geocentric model of the world.

In this model, the Earth is the center of everything, and the Sun and other planets revolve around it. This was fine with the clergy. They quite rigidly adhered to judgments emphasizing that first God created darkness and light, and then the Earth, which he endowed with life. Any other opinions about the model of the world were suppressed immediately and categorically. At the beginning of the first millennium, science in Western Europe was in decline.



At the same time, Indian science developed in the 4th – 8th centuries, especially in the field of mathematics, physics and astronomy. The Indian astronomer and mathematician Aryabhata (476 – 550) proposed a planetary model of the solar system, in which the planets move in elliptical orbits. He believed that the rotation of the heavens is a consequence of the rotation of the Earth. Aryabhata very accurately calculated the size of the Earth and the Moon. The scientist determined the diameter of the Earth at 13,440 km. Aryabhata believed that the Earth has a spherical shape and rotates on its axis.



In the 8th century, the Indian mathematician and astronomer Brahmagupta (598 – 670) began to use algebraic methods for astronomical calculations. He introduced methods for calculating the position of celestial bodies, sunrises and sunsets, solar and lunar eclipses. Brahmagupta believed that the Earth has a spherical shape and moves in the space of the Universe. The astronomer suggested that the Earth attracts all other bodies. In fact, Brahmagupta spoke about the existence of universal gravity.

It cannot be ruled out that the development of astronomy and mathematics in India had a serious impact on researchers in Central Asia.

In Central Asia in the 9th – 15th centuries. long before the first discoveries of the heliocentric system of the world of N. Copernicus, philosophers, mathematicians and astronomers reflected on the structure of the universe. In their scientific research, they used the achievements of scientists from Ancient Greece and India.

Muhammad Al-Khorezmi

Muhammad Al-Khorezmi

In Khorezm in the first half of the 9th century, the Baghdad mathematician and astronomer Muhammad Al-Khorezmi (783 – 850) invented the astrolabe and significantly improved the tables of planetary motion compiled by Ptolemy.



At the end of the 10th century and in the first half of the 11th century, an astronomer from Khorezm Biruni (973 – 1048) claimed that the Earth has a spherical shape. Based on the shape of the planet, he substantiated the duration of days and nights at different times of the year, and also quite accurately (41,550 km) determined the dimensions of the Earth (the circumference along the equator). Biruni was critical of the teachings of K. Ptolemy. He believed that the Sun does not revolve around the Earth, but the Earth revolves around the Sun. In fact, five hundred years before N. Copernicus, Biruni suggested a heliocentric structure of the world. Statue of Al-Biruni in the Pavilion of Persian Scholars in front of the UN Office in Vienna, Austria

Ibn Sina (Avicenna)

Avicenna Ibn Sina

The outstanding founder of Central Asian medicine, Tajik mathematician and astronomer Ibn Sina (Avicenna) was a contemporary of Biruni and shared his views on the structure of the world. Another Tajik philosopher, scientist and great poet Omar Khayyam (circa 1040 – 1123) believed that the Earth, like all celestial bodies, revolves around its axis. And all celestial bodies move in the space of the infinite universe. The universe, according to Omar Khayyam, has existed forever.


The only lifetime portrait of Ulugbek. [Source not specified 536 days] This is a group portrait, which depicts the sons of Ulugbek Abd al-Latif (senior) and Abd al-Aziz (junior) – standing in the lower right corner. The miniature was created by an unknown artist in 1425-1450.

In the XIV-XV centuries, the grandson of the famous Uzbek conqueror Timur, the ruler of Samarkand, astronomer and mathematician Ulug-bek (1394 – 1449) built a huge well-equipped observatory. Modern instruments of the observatory made it possible to achieve such accuracy in observations, which remained unsurpassed more than a century later.

Ulug-bek (1394 - 1449) built a huge well-equipped observatory
Ulug-bek observatory (Samarkand)

Together with Samarkand astronomers, Ulug-bek published a detailed catalog “Star Tables” containing information on the exact position of 1018 stars in the sky. For two centuries, European astronomers republished this popular catalog and used the data from the book. They also published tables of planetary motion.


The achievements of Central Asian astronomers, mathematicians and philosophers did not go unnoticed by scientists in Western Europe. Some of the European astronomers and mathematicians refer to the work of Indian and Central Asian researchers.

Nicolaus Copernicus

In Western Europe, serious changes in views on the structure of the Universe took place only during the Renaissance (XV-XVI centuries). The main troublemaker was the Polish astronomer and mathematician Nicolaus Copernicus (02.19.1473 – 05.24.1543), who presented a new astronomical heliocentric system of the world, in which the Sun occupied the central place, and the Earth and all other planets revolved around it.

He described the new astronomical model in six volumes of his main work “On the Rotation of the Celestial Spheres.” The work on this multivolume edition took almost 40 years. N. Copernicus constantly refined the calculations on the rotation of the planets, entered them into tables, edited the texts. For a long time he did not dare to publish his work, knowing full well that he will have many opponents who think in traditional but already outdated categories. The work was released in the year of his death in 1543.

At first, she was favorably received by the Catholic Church. Moreover, Pope Clement VII attended a lecture on the heliocentric approach to planetary studies. However, some bishops considered the new views dangerous and actively criticized heliocentrism. In 1616, the Theological Commission of the Catholic Church and the Inquisition considered Copernicus’s theory absurd, ludicrous, and formally heretical. They banned it for 4 years until some provisions of the composition were corrected. Copernicus’ work was repeatedly corrected and only in 1835 was it excluded from the Roman Index of Prohibited Books.

N. Copernicus arguably proved that the Earth has a spherical shape, that the planets revolve around their axis and in their orbits around the Sun, that not the Earth, but the Sun is the center of the Universe, that the distance between the Earth and the Sun is very small compared to the distance between the Earth and fixed stars. He decisively refuted the views of philosophers and astronomers of the ancient world, citing indisputable evidence and calculations. Copernicus offered a completely new look at the structure of the world and radically changed the approaches to the study of the solar system and the entire universe.

Giordano Bruno

Giordano Bruno

The Italian philosopher and poet Giordano Bruno (1548 – 1600), developing the views of N. Copernicus, suggested that the stars are the same suns as ours, only very distant, and they have their own planets. That the Universe is infinite and there is a huge number of worlds like ours in it. That the world is homogeneous and consists of five elements – earth, water, fire, air and ether. And also that life is possible on other planets.

On the denunciation of the ill-wisher, D. Bruno was put in prison, where he was persistently offered to abandon his views on the Universe. The six-year efforts of the Inquisition did not bear fruit, and the courageous, unyielding and devoted philosopher was burned to death in Rome in the Square of Flowers.

Nicolaus Copernicus and Giordano Bruno pioneered a new scientific approach to understanding the universe. The work of their lives was successfully continued by the Italian physicist, astronomer and mathematician Galileo Galilei, French philosopher, mathematician, physicist and creator of analytical geometry Rene Descartes, German astronomer and discoverer of the laws of motion of the planets of the solar system, Johannes Kepler, as well as the Dutch astronomer, physicist and inventor of the first pendulum hours Christian Huygens.

Galileo Galilei

Galileo discovered four moons of Jupiter, saw that the Milky Way is a cluster of distant stars. He proved that the Earth and other planets of the solar system revolve around the Sun, and the Moon revolves around the Earth. Galileo was able to see spots on the Sun and concluded that the Sun also revolves on its axis. He determined that the orbits of Venus and Mercury are closer to the Sun than the orbit of the Earth. Using his own optical technique, Galileo discovered the rings of Saturn and the planet Neptune.

His observations and discoveries completely refuted the views of the geocentrists Aristotle and Ptolemy, and supported the position of Copernicus’s heliocentric worldview. Throughout his life, Galileo not only adhered to the heliocentric system of building the world, but also tried to reconcile the Church with the teachings of Copernicus.

Despite his warm and even friendly relations with marquises and dukes, high-ranking cardinals and abbots, support for Copernicus’s theory led to a violent conflict with the Catholic Church and the Inquisition. Only the loyal attitude of Pope Urban VIII helped him avoid execution.

In 1633, Galileo Galilei was imprisoned. During his brief arrest, he renounced the ideas of Copernicus and his theory of heliocentrism. The rest of his life, until his death, he spent under house arrest in his villa in Tuscany.

Rene Descartes

The French philosopher, mathematician and physicist René Descartes (1596-1650), fearing persecution by the Inquisition, decided not to publish some of his works during his lifetime. Nevertheless, he also failed to avoid tension in his relations with the Church.

Engaged in mechanics, optics and thinking about the structure of the Universe, Descartes, in addition to ordinary matter, recognized the presence of invisible subtle matter, which ensures the action of the force of gravity, electricity, magnetism and the manifestation of heat.

He formulated the laws of light propagation, reflection and refraction, explained the appearance of the rainbow and expressed the opinion that the ether is the transmitter of light in the Universe.

Johannes Kepler

The German physicist, mathematician, astronomer, mechanic and optician Johannes Kepler (1571 – 1630) played an invaluable role in the development of views on the Universe. He envisioned the Universe as a huge sphere with a cavity in the center. The solar system is located in this cavity, and the stars are located around. He considered the sun to be motionless, and the stellar sphere as the boundary of the universe.

Kepler formulated three laws of planetary motion in the Universe. All planets rotate in an ellipse. He determined the speed of rotation of the planets around the Sun and derived mathematical dependences of the change in these speeds with the removal and approach of the planet to the Sun. Kepler significantly improved Copernicus’s heliocentric model of the world and brought the Earth into a series of ordinary spherical planets. The center of the solar system was the sun.

He presented his astronomical discoveries and reflections on the heliocentric system of the Copernican world in three volumes of Copernicus Astronomy, published in 1622. Labor immediately got into the “Index of Forbidden Books”. But the astronomical tables, published by him in 1627, were extremely convenient and were successfully distributed among astronomers. Until the beginning of the 19th century, they regularly served not only scientists, but also sailors in sea crossings.

Christian Huygens

The Dutch mechanic, physicist, mathematician and astronomer Christian Huygens (1629 – 1695) also paid much attention to the study of the Universe. In 1655, using his improved telescope, he described the rings of Saturn and discovered Titan, its moon. The improved telescope made it possible to detect the Orion Nebula, ice at the South Pole of Mars, and binary stars. He theoretically substantiated the flattening of the Earth at the poles and calculated the period of rotation of Mars around its axis.

Huygens made the assumption that other planets are inhabited by people. He tried to determine the distance to the stars by comparing their luminosity with that of the Sun.

Isaac Newton

The works of Huygens and the laws of planetary motion discovered by Kepler became the basis for the creation of I. Newton’s theory of universal gravitation. At the beginning of the eighteenth century, the English physicist, mathematician and astronomer Sir Isaac Newton (1642 – 1727) created a fundamental work “Mathematical Principles of Natural Philosophy”, in which he outlined his views on the reasons for the interaction of cosmic bodies.

In the book, Newton argues that, like the Earth, the Sun moves and certain forces act on it, as on the Earth. He suggested that between any two bodies in the Universe a special force acts – gravitational, that is, attraction. In fact, Newton created the foundations of celestial mechanics, which became defining in scientific research literally before the creation of the theory of relativity and quantum mechanics.

Using the law of gravitation, Newton invented methods for calculating the masses of the Sun and the planets of the solar system, discovered the cause of the ebb and flow, found out the causes of the displacement of the earth’s axis and calculated the period of this displacement with a period of 26,000 years. In the process of research, he built a model of the universe and came to the conclusion that it is infinite.

Immanuel Kant

The concept of the Universe was further developed in the works of the German philosopher, the founder of German classical philosophy, Immanuel Kant (1724-1804). In his work “General Natural History and Theory of the Sky,” Kant developed a model for the origin of the solar system, believing that it originated from a giant gas nebula.

He was the first to suggest that not only the Solar System, but also our Galaxy, along with the entire huge collection of stars and planets, is in motion. That all these stars and planets are held together by the same gravitational forces that are true for the solar system. Kant admitted that our galaxy is not the only one in the Universe, believing that the observed nebulae may be independent galaxies.

We can conclude that in the Middle Ages, humanity was actively and vividly interested in the stars and their existence in the Universe. However, the views of philosophers and astronomers, which contradicted the accepted norms and rules, were brutally suppressed by the Inquisition. Despite this, convinced researchers, defending their ideological views, courageously went to death, to the fire, to prison. The censorship closely and meticulously monitored all new treatises and mercilessly divided them into permitted and prohibited. Old knowledge stubbornly did not yield its positions.

The invention of the telescope made it possible to significantly expand the possibilities of studying space. This opened up previously unknown corners of the Universe to astronomers and included physicists and mathematicians in active work. Discoveries followed one another.

Ptolemy’s geocentric model of the universe gave way to the heliocentric system of the Copernican world. This took almost fifteen centuries. It was no longer the Earth, but the Sun that was considered the center of the Universe. Planets revolved around the Sun. In the views of astronomers and philosophers, the sun and stars, the earth and the planets were no longer flat, but spherical.

The development of mathematics has made it possible to relatively accurately calculate the orbits of the planets, their rotational speeds and distances to them. Astronomers saw not only planets in the starry sky, but also their satellites. The universe, in the eyes of most astronomers and philosophers, was finite and spherical.

Timur Timerbulatov President of the Conti group of companies, scientist, academician of the Russian Academy of Natural Sciences, writer (literary pseudonym Mon Tirey)

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