Plato is my friend, Aristotle is my friend, but my greatest friend is truth.
- Sir Isaac Newton
In preparation for the Gao Shan interview not long ago, in order to avoid appearing overly ignorant and uncultured, I skimmed through 15 of the old classics in "Gao Shan Science Classics." From "The Canon of Medicine" to "Timaeus," from Aristotle's "Physics" to Copernicus' "De Revolutionibus Orbium Coelestium," from "Dialogues" to "Principles" and finally to Einstein's "Relativity."
Books on natural sciences are different from those on humanities. Books on history, society, and literature often offer new insights with repeated readings; however, natural sciences do require keeping up with the latest research developments. Yet, from the perspective of studying the history of science, understanding the scientific spirit, and mastering scientific methods, these old classics still hold great significance.
It was these scientists who gazed at the sky and pursued fundamental questions that brought about modern science. For example, the idea that the Earth revolves around the Sun was only achieved through continuous revisions, corrections, and even rejections and rebuilds of previous theories.
Pythagoras was the first to propose that the Earth is a sphere.
Plato believed that the most perfect form in the universe is the sphere, with uniform circular motion, so the universe is harmonious and beautiful.
Aristotle summarized three scientific methods to prove that the Earth is spherical:
The higher you go north, the higher the North Star appears; the further south you go, the lower the North Star appears.
For sailing ships at sea, the mast top is seen first, then gradually the ship's body, and finally the entire ship becomes visible.
During a lunar eclipse, the shape of the Earth's shadow on the Moon is round.
Aristotle also proposed the geocentric theory.
Ptolemy developed and perfected the geocentric model.
In order to explain the retrograde motion of some planets, Ptolemy proposed the epicycle theory, which stated that these celestial bodies moved along smaller orbits while also orbiting the Earth.
Then came the long Middle Ages, during which the geocentric model in Europe was regarded as the official cosmology until Copernicus ushered in a new chapter of the Renaissance.
Copernicus found the epicycle unnatural, so he proposed the heliocentric theory, suggesting that the orbit of the Earth was circular.
Kepler formulated the three laws of planetary motion, correcting the shape of Earth's orbital path.
The Law of Ellipses: All planets move in elliptical orbits with the sun at one focus.
The Law of Areas: The line joining a planet to the sun sweeps over equal areas in equal time intervals.
The Harmonic Law: The square of the sidereal period of any planet is proportional to the cube of the semi-major axis of its orbit (ai).
Galileo made an astronomical telescope and discovered some new astronomical phenomena that could support the heliocentric theory.
He proposed in the "Dialogue" that the rotation of the Earth around its axis and the revolution around the sun cause the acceleration and deceleration of motion on the Earth's surface, which triggers the tidal ebb and flow of seawater.
By demonstrating the consistency between Kepler's laws of planetary motion and his theory of gravity, Newton showed that the movements of terrestrial objects and celestial bodies both follow the same natural laws, providing strong theoretical support for the heliocentric theory.
Newton also revised the principle of tides, attributing them to the influence of the Moon.
Therefore, the idea that the Earth orbits the Sun was not initially a consensus among everyone. It took generations of great scientists continuously seeking truth and exploring to bring us closer to reality.
In June 1633, Galileo was convicted for being "suspect of heresy," and when he signed the statement declaring his previous statements invalid, he muttered quietly, but the Earth does revolve around the Sun.
In October 1992, 360 years after Galileo's wrongful conviction, he was finally exonerated by the Pope of Vatican. Our geography textbooks describe the basic forms of Earth's movement as follows: while continuously rotating on its axis, the Earth revolves around the Sun.