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# Renaissance men - part two of the first chapter in the book "History of Science" by John Gribbin

The book was published by "Aliyat HaGeg Books and Yediot Books". From English: Dafna Levy. In this section, the subsections "The Orbits of the Planets", "Leonard Diggs and the Telescope", and "Thomas Diggs and the Infinite Universe"

The orbits of the planets

The particularly impressive thing about Copernicus' complete universe model was that by placing the earth in orbit around the sun, he automatically placed all the planets in a logical sequence. Since ancient times, astronomers have been puzzled by the mystery of the planet Hama and Venus, which can only be seen from Earth at dawn or at dusk, while the other three planets can be seen at all hours of the night. Ptolemy's explanation (more precisely, the well-known explanation he summarized in the Almagest) was that the planet Hama and Venus "accompany" the sun as it circled the earth each year. But according to Copernicus' method, it was the Earth that circled the Sun every year, and the explanation for the two types of motion of the planets was simply that the orbits of the planet Hama and Venus passed within the orbit of the Earth (closer to the Sun than we are), while the orbits of Mars, Jupiter and Saturn passed outside the orbit of the Earth The earth (further from the sun than we are). By taking into account the movement of the Earth, Copernicus was able to calculate the amount of time it takes for each of the planets to make one lap around the Sun, and these periods created an orderly sequence starting with the planet with the shortest "year", for Venus, the Earth , Mars and Jupiter, and ending with Saturn, which has the longest "year".

But that's not the end of the story. The observed pattern of the planets' behavior is also related, in the Copernican model, to the ratio between their distance from the Sun and the Earth's distance from the Sun. Without knowing even one of the distances in absolute terms, he managed to place the planets in order of increasing distance from the sun. The order is kept as it was - hot planet, Venus, Earth, Mars, Jupiter and Saturn. A profound truth about the nature of the universe was clearly revealed here. There was much more to Copernicus' astronomy, for those with eyes in their head, than the simple assertion that the earth revolved around the sun.

Leonard Diggs and the Telescope

One of the few people who clearly saw the implications of Copernicus' model immediately after the publication of De Revolutionibus was the English astronomer Thomas Digges. Diggs was not only a scientist, but one of the first popularizers of science - not really the first, since he actually followed in the footsteps of his father, Leonard. Leonard Digges was born in about 1520, but very little is known about his early life. He studied at Oxford University and became famous as a mathematician and land surveyor. He was also the author of several books written in English - a very rare thing at that time. The first of his books, A General Prognostication, was published in 1553, ten years after De Revolutionibus, and became a bestseller, in large part because it was written in the spoken language, although in one crucial respect it had already become obsolete. In his book, Leonard Digges provided a perpetual calendar, material on weather theory, and an abundance of astronomical material, including a description of Ptolemy's picture of the world - the book was not very different from the peasant calendars that were popular in the following centuries.

Leonard Digges, as part of his measuring work, invented the measuring telescope, the theodolite, in 1551 - approx. Around the same time, his interest in accurate vision at long distances led him to invent the mirror telescope (and probably also the lens telescope), although no publicity was given to these inventions at the time. One of the reasons for the lack of development of these ideas was that the career of Diggs Sr. was abruptly cut short in 1554, when he participated in the failed rebellion, led by Sir Thomas Wyatt, against the new queen, Mary (the Catholic), who ascended the throne in 1553- with the death of her father Henry VIII . Leonard Diggs was initially sentenced to death for his part in the rebellion, but his sentence was commuted. However, he lost all his possessions and spent the rest of his life (he died in 1559-) in an unsuccessful struggle to win them back.

When Leonard Diggs died, his son Thomas was about 13 years old (we do not know the exact date of birth), and he was raised by his guardian, John Dee. Dee was a typical "natural philosopher" of the Renaissance: skilled mathematician, student of alchemy, philosopher and astrologer - not exactly typical - of Queen Elizabeth (who came to power in 1558-). It is possible that he, like the playwright Christopher Marlowe, was a secret agent in the service of the crown. He was also, as the story goes, an ardent follower of the Copernican model, although he himself published nothing on the subject. Dee's house gave Thomas Digges access to a library that contained over a thousand manuscripts which he devoured before publishing his first mathematical treatise in 1571, the same year in which he printed a book written by his father (Pantometria), which contained the first public discussion of his father's invention of the telescope. In the introduction to the book, Thomas Diggs describes how

"My father, through tiresome and prolonged attempts, with the help of mathematical demonstrations, succeeded at different times, using matching mirrors placed at desired angles, not only to discover distant things, to read letters, coins and inscriptions that friends kept for this purpose in vast fields, but also to report what was happening at that moment in places private a dozen kilometers away."

Thomas Diggs and the Infinite Universe

Thomas also studied the sky on his own, and made observations of a supernova that was seen in 1572. Some of the observations were used by Tycho Brahe when he analyzed the event.

But the most important publication of Thomas Diggs appeared in 1576. It was an edited and revised edition of his father's last book, now called Prognostication Everlasting, and it included a detailed discussion of Copernicus' model of the universe - the first description of its kind in English. But Digges went further than Copernicus. He claimed in the book that the universe was infinite, and included a diagram that showed the sun in the center, with all the planets orbiting around it, and masses of stars spreading out to infinity in all directions. It was an incredible leap into the unknown. Diggs gave no reason for his claim, but it is very likely that he was looking through the telescope at the Milky Way, and that the masses of stars he saw there convinced him that the stars were other suns scattered widely throughout the infinite universe.

But Digges did not dedicate his life to science any more than Copernicus did, and he did not follow up on his ideas. As he was the son of a prominent Protestant who suffered at the hands of Queen Mary, and was a member of Dee's household (a protégé of Queen Elizabeth), Thomas Diggs became a member of parliament - elected for two separate terms - and an adviser to the government. He also served as general recruiting officer for the English forces in the Netherlands in 1586-1593, when England helped the Protestant Dutch to free themselves from the rule of Catholic Spain. He died in 1595. In the meantime, Galileo was already a well-known professor of mathematics in Padua, and the Catholic Church began to attack Copernicus' picture of the universe because heretics like Giordano Bruno (Bruno), who was embroiled in a long trial that ended with his being put on the stake in 1600, had adopted it.

Introduction to the book "History of Science"

First part of the first chapter, Renaissance people

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