Science is a way to organize knowledge and understanding about the world. From the beginning, science was closely linked to philosophy and the aim was to find reliable and logical explanations to things that were observed or predicted. Today, science is often divided into natural science and physical science. Distinguishing between the branches is not always easy, and often a subject can be approached in several different ways, which means that they do not belong in one category.

Physical Science

Things made by man are studied in physical science, and nonliving systems such as physics, mathematics, material science and computers are included. Chemistry, the composition and structure of matter, is a physical science. Another is Earth science, the study of the composition of Earth and areas such as water, geology and atmospheres. Physics is a fundamental science, which means that sciences such as biology and chemistry obey the laws of physics. Mathematics is, according to some mathematicians, not a science, since it cannot be experimentally falsifiable. Others believe that mathematical principles are discovered rather than created.

Natural Science

Living things and materials are explored in natural science. This branch was previously called natural philosophy and prior to the 17th century it was less scientific in application. The English scientist Francis Bacon introduced scientific methods and this led to a planned empirical examination of a subject. Natural sciences include subjects such as biology, medicine and natural history. Natural sciences form the basis in applied sciences, which applies scientific knowledge and tests it in a practical situation.

Natural Science and Social Science

New ideas and discoveries lead to the development of a range of new subjects during the 19th and 20th century. Many of these were related to living things, and methodologies used to study physical and natural sciences were used to understand human behavior in new contexts, for example, psychology, sociology, education and criminology. Today, these subjects are called social sciences.

Physical and Natural Science

Chemistry is connected to several natural sciences such as astronomy, biology and Earth science. The links between physical natural sciences are strong and a subject can belong in both categories. The focus and the research questions determine which category a subject may belong to. A subject such as astronomy can focus on observational astronomy where the focus is on nonliving objects. Astronomy can also explore the living conditions on a planet, making it more closely related to natural science.