The branches of science

Scientific study can be divided into four major groups: (1) mathematics and logic, (2) the physical sciences, (3) the life sciences, and (4) the social sciences. Within these main categories are many smaller groupings of closely related specialties. For example, anthropology, psychology, and sociology are behavioral sciences included in the category of the social sciences. Geology, meteorology, physical geography, and physical oceanography are grouped together as the earth sciences within the category of the physical sciences.

As scientific knowledge has grown and become increasingly complicated, many new fields of study have emerged. and it is often hard to tell where one science ends and another begins. For instance, both chemistry and physics deal with atomic structure. Both paleontology and geology study the age of rocks in the earth. Many of the most important scientific advances have resulted from the exchange of ideas and methods among different branches of science.

Mathematics and logic are not based on experimental testing. But they can be considered part of science because they are essential tools in almost all scientific study. Mathematics enables scientists to prepare exact statements of their findings and theories and to make numerical predictions about what will happen in the future. Logic provides the basis for all scientific reasoning.

The physical sciences examine the nature of the universe. They study the structure and properties of nonliving matter, from tiny atoms to vast galaxies. The physical sciences include (1) astronomy, (2) chemistry, (3) geology, (4) meteorology, and (5) physics.

Astronomy is the study of comets, meteors, galaxies, planets, stars, and other objects in space. Astronomers map the locations of heavenly bodies and investigate the physical and chemical processes that occur in celestial objects. They also study the structure, composition, size, and history of the universe.

Chemistry studies natural and artificial substances to determine their composition and structure and the changes that occur when they combine and form other substances. Chemists take molecules apart and put them together in new ways. They try to find out why chemical reactions occur and how they can be controlled. Organic chemistry deals with most compounds containing the element carbon, and inorganic chemistry concerns all other compounds. Radiochemistry in vest gates radioactive substances and their uses. Stereochemistry examines the different chemical properties that result when compounds of the same formula differ in the relative position of their atoms in three-dimensional space. Physical chemistry studies the effects of light, heat, and other forms of energy on chemical processes.

Geology investigates the composition, structure, and history of the earth. Geologists analyze how such forces as earthquakes, volcanic eruptions, and wind or water erosion change the earth's surface. They also study meteorites and materials brought back from the moon. Branches of geology include petrology, the study of rocks; mineralogy, the study of minerals; and seismology, the study of earthquakes. Geochronology seeks to determine the age and history of the earth and its parts.

Meteorology is the study of the earth’s atmosphere and the conditions that produce weather. Meteorologists try to predict the weather. They work to develop improved instruments for collecting data about the atmosphere. They also seek better techniques to make weather forecasting more exact. Climatologists analyze weather trends to determine the general pattern of weather that makes up an area's climate.

Physics is concerned with matter and energy. Physicists study mechanics, heat, light, sound, electricity, magnetism, and the properties of matter. Atomic physics involves the study of the structure and properties of atoms, and nuclear physics focuses on the makeup and behavior of the nuclei of atoms. Particle physics deals with the nature of electrons, protons, and other tiny bits of matter smaller than atomic nuclei. Cryogenics examines the behavior of matter at extremely low temperatures, and plasma physics investigates the behavior of gases that ionize to create a form of matter called plasma. Solid-state physics studies the properties of extremely pure crystals and other solid materials.

The life sciences, also called the biological sciences or biology, involve the study of living organisms. There are two main fields of the life sciences. Botany deals with plants, and zoology with animals. Botany and zoology are further divided into various branches, each of which can be subdivided into areas of special study. Many of the branches, such as anatomy and physiology, overlap with, and contribute greatly to, the study of medicine.

Anatomy examines the structure of living things. Anatomists investigate the parts of organisms and how the parts are related. Histology deals with tissues, and cytology with the fine structures of individual cells. Comparative anatomy studies similarities and differences in the body structure of animals and provides clues to how certain animals might have evolved. Physiology deals with the normal functions of living things and their parts. For example, physiologists study how nerve fibers transmit impulses and how organisms take in and use food. Biochemistry examines the chemical processes that are involved in the actions of the different parts of plants and animals. Biophysics investigates the physical processes involved in the functioning of the various parts of living things.

The field of genetics is concerned with how plants and animals pass on characteristics to their offspring. Molecular biology examines the structure and function of proteins and other large molecules essential to life. Paleontology investigates the forms of life that existed in prehistoric times. Taxonomy involves the classification of living things. Sociobiology deals with the biological basis for the social behavior of people and other animals. Ecology focuses on the relationships living things have to one another and to their environment.

Some life sciences concentrate on certain kinds of organisms. For example, bacteriology is the study of bacteria, and ornithology is the study of birds. Some other life sciences investigate the organisms that live in a specific environment. Marine biology, for instance, studies the plants and animals of the sea.

The social sciences deal with the individuals, groups, and institutions that make up human society. They focus on human relationships and the interactions between individuals and their families, religious or ethnic communities, cities, governments, and other social groups. Social scientists attempt to develop general "laws" of human behavior. But their task is difficult because it is hard to design controlled experiments involving human beings. Social scientists must therefore rely heavily on careful observations and the systematic collection of data to arrive at their conclusions. The use of statistics and mathematical models is important in analyzing information and developing theories in the social sciences. The main branches of the social sciences include (1) anthropology, (2) economics, (3) political science, (4) psychology, and (5) sociology.

Anthropology investigates the origin and development of human cultures and of human physical characteristics. Anthropologists study various groups of people to determine their similarities and differences. They compare the arts, beliefs, customs, daily life, inventions, languages, social relationships, and values of different cultures. Archaeology traces cultural development by studying the things earlier peoples made and used.

Economics examines how people produce goods and services, how they distribute them among themselves, and how they use them. Economists deal with problems in such areas as management and labor relations, the setting of wages and prices, and the use of natural resources. They use computers and statistical analysis to construct mathematical models that enable them to determine how various economic systems work and to predict the effect of changes in the systems.

Political science studies forms of government, political parties, pressure groups, elections, and other aspects of politics. Political scientists try to develop theories about political power and behavior and seek to discover what kinds of government may benefit people the most under given circumstances. They also measure public opinion.

Psychology involves investigation of mental processes and behavior. Physiological psychologists study how the nerves and the brain work. Behavioral psychologists observe and record the ways in which people and other animals relate to one another and to the environment. They use systematic methods to examine people's thoughts, feelings, and personality traits. Psychologists also explore the causes of mental disorders and possible methods of treatment.

Sociology studies the nature, origin, and development of human society and community life. Sociologists investigate the interrelationships among individuals and groups in a society. They examine cultural influences, standards of behavior, and other factors that can affect general social conditions. They also explore the causes of crime, divorce, poverty, and other social problems.