Dialogue Concerning the Two Chief World Systems, Ptolemaic and Copernican

About this book

Salviati speaks for Copernicus, the clever Venetian Sagredo weighs both sides with common sense, and Simplicio defends Aristotle in good faith. Why does a stone dropped from a tower land at its foot if the earth is turning? Why can you not tell, shut in a ship's cabin with butterflies, flies and a bowl of little fish, whether the ship is moving? What do the mountains of the moon, the moons of Jupiter, the phases of Venus and the spots on the sun tell us? And why, Galileo believed, does the sea rise and fall?

Rendered into modern English by BlusaBooks with the help of AI tools, working from images of the pages of the 1632 Florence first edition. Every sentence, not a selection or a summary: all four days, the dedication and the famous preface "To the Discerning Reader". The ideas of the age (spheres, elements, the "incorruptible heavens") are kept as Galileo wrote them; the notes explain them.

What is inside

• the title page and the frontispiece of 1632: Aristotle, Ptolemy and Copernicus in conversation
• the First Day: are the heavens unchangeable? new stars, sunspots, the mountains of the moon
• the Second Day: the daily rotation of the earth, the stone from the mast, "Galileo's ship", cannon shots and birds
• the Third Day: the annual motion around the sun, the new star of 1572 with all the calculations, the Copernican system
• the Fourth Day: the tides, Galileo's "chief proof" (and why it was wrong)
• all 713 of Galileo's own marginal notes, the original diagrams from the 1632 edition and the calculations in framed tables
• 454 short footnotes on the same page: who each person was, what the old terms mean, what we know today
• colour illustrations: three friends in a Venetian palace, the ship's cabin with fish and butterflies, high tide in Venice (illustrations created with AI tools)
• a foreword on Galileo, the telescope, the ban of 1616 and the trial of 1633; commentary at the end for each day: in plain words, what Galileo argues, what we know today

Who it is for

Readers of the history of science and astronomy, students and teachers of physics, lovers of classic and banned books, anyone curious about Galileo and the Inquisition. A thoughtful gift for a lover of science and old books.

A historical source: Galileo's physics is that of 1632, and his theory of the tides was wrong. The notes and commentary explain what we know today.