Science, in the broadest sense of the term, refers to any system of knowledge attained by verifiable means. In a more restricted sense, science refers to a system of acquiring knowledge based on empiricism, experimentation, and methodological naturalism, as well as to the organized body of knowledge humans have gained by such research.
Scientists maintain that scientific investigation must adhere to the scientific method, a process for properly developing and evaluating natural explanations for observable phenomena based on empirical study and independent verification. Science typically, therefore, rejects supernatural explanations, arguments from authority, and biased observational studies.
Fields of science are commonly classified along two major lines: Natural sciences, which study natural phenomena; and Social sciences, which study human behavior and societies. Whether mathematics is a science is a matter of perspective.
Applied Science is the exact science of applying knowledge from one or more natural scientific fields to practical problems. Many applied sciences can be considered forms of engineering. Applied science is important for technology development. Its use in industrial settings is usually referred to as research and development.
The human race’s use of technology began with the conversion of natural resources into simple tools. The prehistorical discovery of the ability to control fire increased the available sources of food, and the invention of the wheel helped humans in travelling in and controlling their environment. Recent technological developments, including the printing press, the telephone, and the Internet, have lessened physical barriers to communication and allowed humans to interact on a global scale. However, not all technology has been used for peaceful purposes; the development of weapons of ever-increasing destructive power has progressed throughout history, from clubs to nuclear weapons.
Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth’s atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.
Since the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring and analyzing data, mainly using basic principles of physics. Theoretical astronomy is oriented towards the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the observational results, and observations being used to confirm theoretical results.
Historically, amateur astronomers have contributed to many important astronomical discoveries, and astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and observation of transient phenomena.
Biology is the study of life. It is a field of empirical science that examines the structure, function, growth, origin, evolution, and distribution of living things both past and present. It classifies and describes the various forms of organisms, how organisms function, how species come into existence, and the interactions they have with each other and with the natural environment. Biology includes a broad spectrum of fields that address phenomena related to living organisms (biological phenomena), including botany, zoology and physiology. There are four broad unifying principles of biology:
Cell theory. All living organisms are composed of at least one cell and the cell is the basic unit of function in all organisms.
Evolution. Through natural selection or genetic drift, a population’s inherited traits change from generation to generation.
Gene theory. A living organism’s traits are encoded in the DNA, the fundamental component of genes.
Homeostasis. The physiological processes that allow an organism to maintain its internal environment notwithstanding its external environment.
Chemistry is the science concerned with the reactions, transformations and aggregations of matter, as well as accompanying energy and entropy changes during such transformations. It is also a field of study to investigate matter from the atomic to macromolecular scale, such as molecules, crystals. According to quantum chemistry, all physical and chemical properties of substances are a consequence of their structure at the molecular or atomic scale.
The structure of the world we commonly experience and the properties of the matter we commonly interact with are determined by properties of chemical substances and their interactions. Steel is harder than iron because its atoms are bound together in a more rigid crystalline lattice. Wood burns or undergoes rapid oxidation because it can react spontaneously with oxygen in a chemical reaction above a certain temperature.
The interactions studied in chemistry may be between two chemical substances or between matter and energy. Traditional chemistry involves interactions between substances in chemical reactions, where one or more substances become one or more other substances.
Earth Science is an all-embracing term for the sciences related to the planet Earth. The major historic disciplines use physics, geology, geography, meteorology, mathematics, chemistry and biology to build a quantitative understanding of the principal areas or spheres of the Earth system.
Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere. These correspond to rocks, water, air, and life. Some practitioners include the crysophere (ice) as a distinct portion of the hydrosphere and the pedosphere (soil) as an active, intermixed sphere as part of Earth’s spheres.
Geology describes the rocky parts of the Earth’s crust (or lithosphere) and its historic development.
Geophysics and Geodesy investigate the figure of the Earth, its reaction to forces and its magnetic and gravity fields.
Oceanography and hydrology describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere).
Atmospheric sciences cover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere (~1000 km).
Physics is the branch of science concerned with the discovery and characterization of universal laws which govern matter, energy, space, and time. The role of physics, then, is to provide a logically ordered picture of nature in agreement with experience. Discoveries in physics resonate throughout the natural sciences, and physics has been described as the “fundamental science” because other fields, such as chemistry and biology, investigate systems whose properties depend on the laws of physics.
The emergence of modern physics as a science distinct from natural philosophy began with the scientific revolution of the 16th and 17th centuries and continued through the dawn of modern physics in the early 20th century. Research today progresses on a vast array of topics, including high-temperature superconductivity, quantum computing, the search for the Higgs boson, and the attempt to develop a theory of quantum gravity. Firmly grounded in observations and experiments, with a rich set of theories expressed in elegant mathematics, physics has made a multitude of contributions to science, technology, and philosophy.
The Social Sciences are a group of academic disciplines that study human aspects of the world. They diverge from the arts and humanities in that the social sciences tend to emphasize the use of the scientific method in the study of humanity, including quantitative and qualitative methods.
Some social science subfields have become very quantitative in methodology or behavioral in approach. Conversely, the interdisciplinary and cross-disciplinary nature of scientific inquiry into human behavior and social and environmental factors affecting it have made many of the so-called hard sciences dependent on social science methodology. Examples of boundary blurring include emerging disciplines like social studies of medicine, neuropsychology, bioeconomics and the history and sociology of science. Increasingly, quantitative and qualitative methods are being integrated in the study of human action and its implications and consequences.