The Common Links in Our Journey

Abstract

Among all the living species, humans are the only ones who observe the world and ask questions about how and why. The ability to seek patterns from observations and formulate theories to explain and predict past and future events is the essence of science. In this book (and Volume 1), we have explained why astronomy is the oldest science. Recognizing that the celestial objects move with repeatable patterns, our ancestors developed quantitative models to describe these patterns. They were also motivated by the desire to seek possible connections between heaven, Earth, and humanity. The ancient discipline of astrology later became the discipline of astronomy, which systematically studies the positions, movements, brightness, and shapes of celestial objects. Astronomy further evolved into astrophysics, using our knowledge of terrestrial physics acquired in the laboratory to understand the structure of celestial objects. Spectroscopy made possible the identification of atoms and molecules in stars, interstellar space, and galaxies. These identifications suggest that the laws of physics and chemistry are applicable over large spatial scales across the Universe and back in time to billions of years ago.