Erasmus 2017-2018 Inventors and innovators Thales of Miletus Thales of Miletus (624-546 BC) was a pre-Socratic Greek philosopher, mathematician, and astronomer from Miletus in Asia Minor. He was one of the Seven Sages of Greece. Many, most notably Aristotle, regarded him as the first philosopher in the Greek tradition and he is otherwise historically recognized as the first individual in Western civilization known to have entertained and engaged in scientific philosophy. Thales is recognized for breaking from the use of mythology to explain the world and the universe, and instead explaining natural objects and phenomena by theories and hypotheses, in a precursor to modern science. Aristotle reported Thales' hypothesis that the originating principle of nature and the nature of matter was a single material substance: water.
Mathematics In mathematics, Thales used geometry to calculate the heights of pyramids and the distance of ships from the shore. He is the first known individual to use deductive reasoning applied to geometry, by deriving four corollaries to Thales' theorem. He is the first known individual to whom a mathematical discovery has been attributed.
Intercept theorem The intercept theorem states that: “If two intersecting lines are cut by parallel lines, the line segments cut by the parallel lines from one of the lines are proportional to the corresponding line segments cut by them from the other line” (see figure 1).
Figure 1: Intercept theorem
ďƒ˜ Height of the Cheops pyramid According to some historical sources the Greek mathematician Thales applied the intercept theorem to determine the height of the Cheops' pyramid.[1] The following description illustrates the use of the intercept theorem to compute the height of the pyramid. It does not however recount Thales' original work, which was lost. Thales measured the length of the pyramid's base and the height of his pole. Then at the same time of the day (so that the rays of the sun were parallel and therefore he could apply the intercept theorem) measured the length of the pyramid's shadow and the length of the pole's shadow. This yielded the following data: 1. height of the pole (A): 1.63 m 2. shadow of the pole (B): 2 m 3. length of the pyramid base: 230 m 4. shadow of the pyramid: 65 m From this he computed: C = 65 m + 230m/2 = 180 m
Figure 2: Measuring pieces
Knowing A, B and C he was now able to apply the intercept theorem to compute D = C * A / B = 1.63m * 180m / 2m = 146.7 m
Figure 3: computing C and D
 Astronomy Thales predicted the solar eclipse of May 28, 585 BC. Thales also described the position of Ursa Minor, and thought the constellation might be useful as a guide for navigation at sea. He calculated the duration of the year and the timings of the equinoxes and solstices. He is additionally attributed with the first observation of the Hyades and with calculating the position of the Pleiades.
 Influences Thales had a great influence on other Greek thinkers, like Anaximander and Pythagoras and therefore on Western history.
Sources: https://en.wikipedia.org/wiki/Thales_of_Miletus#Astronomy https://wikivisually.com/wiki/Intercept_theorem#Height_of_the_Cheops_pyramid