温伯格《解释世界》第二部分 希腊天文学

古代科学取得的最伟大成就是在天文学领域。其中一个原因是因为天文现象与其他各种现象相比更加简单直观。古人那时并不完全明白，实际上当时的地球以及其他行星同今天一样围绕太阳在近圆形轨道以近匀速运行，它们都受到唯一的力—重力的作用，而且它们也以近匀速沿各自自转轴自转。月亮围绕地球运动也一样。这样从地球上观察，太阳，月亮，以及其他行星都呈规律性运行，人们可以深入研究这些运行规律并做出极其精确的预测。 古代天文学的另一个特色是其实用性，这点古代物理学做不到。有关天文学的实用性会在第六章做介绍。 第七章将会讨论希腊化时代科学的一个杰出成就（虽然存在不少错误）：即对太阳，月亮和地球大小的测量，以及地球与太阳和月亮间的距离。第八章探讨行星的视运行问题。一直到中世纪这个问题仍然困扰着天文学家，最终引发了现代科学的诞生。

The science that in the ancient world saw the greatest progress was astronomy. One reason is that astronomical phenomena are simpler than those on the Earth’s surface. Though the ancients did not know it, then as now the Earth and the other planets moved around the Sun on nearly circular orbits, at nearly constant velocities, under the influence of a single force—gravitation—and they spun on their axes at essentially constant rates. The same applied to the Moon in its motion around the Earth. In consequence the Sun, Moon, and planets appeared from Earth to move in a regular and predictable way that could be and was studied with considerable precision. The other special feature of ancient astronomy is that it was useful, in a way that ancient physics generally was not. The uses of astronomy are discussed in Chapter 6. Chapter 7 discusses what, flawed as it was, can be considered a triumph of Hellenistic science: the measurement of the sizes of the Sun, Moon, and Earth, and the distances to the Sun and Moon. Chapter 8 treats the problem posed by the apparent motion of the planets, a problem that continued to concern astronomers through the Middle Ages, and that eventually led to the birth of modern science.