An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time

THE PROCESS OF SCIENCE: HOW DO WE KNOW?

The nature of the universe, its age, its birth and life story, have been deduced through the process of science. This process has many aspects and stages. In the case of astronomy, it usually starts with making careful observations and measurements -- something your students can begin to do through inspection of astronomical images, and observation of the real sky. Together with our knowledge of the laws of physics, developed in laboratories here on Earth, these observations provide the basis for our understanding of the universe. From continuing observations, astronomers develop models and theories to explain how things work in the realms of the planets, stars, and galaxies.

In science, we test our ideas by making further observations and doing experiments. All suggestions (hypotheses) must ultimately be confirmed by testing them against the evidence of the real world. As much as possible, we must leave our prejudices and preferences outside the laboratory or observatory door. When the experiments and observations have spoken, we must accept their results gracefully.

When scientists measured the age of the universe (as we will describe in a moment), they did not hope or wish for it to have a particular age, and try to make their results come out according to those wishes. Instead, they did the best they could to understand nature and then reported what their observations had told them.

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An Ancient Universe - Table of Contents

Home | Introduction | The Universe: An Overview | The Process of Science | The Ancient Universe - The Age of the Expanding Universe - The Age of the Oldest Stars - The Age of Light From Distant Galaxies - The Age of the Chemical Elements | The Changing Universe - Changes in the Solar System - Changes in Stars - Changes in the Universe | Science and Religion | Resource Guide | Activities

© Copyright 2001, American Astronomical Society. Permission to reproduce in its entirety for any non-profit, educational purpose is hereby granted. For all other uses contact the publisher: Astronomical Society of the Pacific, 390 Ashton Ave., San Francisco, CA 94112.

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