Science

From prehistoric times onward, human beings have been curious about the world around them and about worlds far away and out of eyesight. What are the laws that govern the universe? What makes our planet the way it is, regarding everything from the humble atom to the largest landmasses and the encompassing atmosphere of Earth? Why does life develop one way instead of another? How has scientific research and technology improved human life and understanding over the centuries? Explore, search, and satisfy your curiosity on these and any number of other topics within the vast realm of science.

Browse Subcategories:
Featured Science Articles
  • Gedankenexperiment
    Gedankenexperiment, (German: “thought experiment”) term used by German-born physicist Albert Einstein to describe his unique approach of using conceptual rather than actual experiments in creating the theory of relativity. For example, Einstein described how at age 16 he watched himself in his…
  • Aristotle
    Philosophy of science
    Philosophy of science, the study, from a philosophical perspective, of the elements of scientific inquiry. This article discusses metaphysical, epistemological, and ethical issues related to the practice and goals of modern science. For treatment of philosophical issues raised by the problems and…
  • The geologic time scale from 650 million years ago to the present, showing major evolutionary events.
    Evolution
    Evolution, theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations. The theory of evolution is one of the…
  • human chromosomes
    Heredity
    Heredity, the sum of all biological processes by which particular characteristics are transmitted from parents to their offspring. The concept of heredity encompasses two seemingly paradoxical observations about organisms: the constancy of a species from generation to generation and the variation…
  • open cluster NGC 290
    Star
    Star, any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources. Of the tens of billions of trillions of stars composing the observable universe, only a very small percentage are visible to the naked eye. Many stars occur in pairs, multiple…
  • Simonyi, Charles; Padalka, Gennady; Barratt, Michael
    Space tourism
    Space tourism, recreational space travel, either on established government-owned vehicles such as the Russian Soyuz and the International Space Station (ISS) or on vehicles fielded by private companies. Since the flight of the world’s first space tourist, American businessman Dennis Tito, on April…
  • astronaut outside the International Space Station
    Space exploration
    Space exploration, the investigation, by means of crewed and uncrewed spacecraft, of the reaches of the universe beyond Earth’s atmosphere and the use of the information so gained to increase knowledge of the cosmos and benefit humanity. A complete list of all crewed spaceflights, with details on…
  • Typology
    Typology, system of groupings (such as “landed gentry” or “rain forests”), usually called types, the members of which are identified by postulating specified attributes that are mutually exclusive and collectively exhaustive—groupings set up to aid demonstration or inquiry by establishing a limited…
  • animal cell
    Cell
    Cell, in biology, the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast. Other cells acquire specialized functions as they mature. These cells…
  • Control group
    Control group, the standard to which comparisons are made in an experiment. Many experiments are designed to include a control group and one or more experimental groups; in fact, some scholars reserve the term experiment for study designs that include a control group. Ideally, the control group and…
  • snake gourd flower
    Angiosperm
    Angiosperm, any of about 300,000 species of flowering plants, the largest and most diverse group within the kingdom Plantae. Angiosperms represent approximately 80 percent of all the known green plants now living. The angiosperms are vascular seed plants in which the ovule (egg) is fertilized and…
  • experiments disproving spontaneous generation
    Scientific hypothesis
    Scientific hypothesis, an idea that proposes a tentative explanation about a phenomenon or a narrow set of phenomena observed in the natural world. The two primary features of a scientific hypothesis are falsifiability and testability, which are reflected in an “If…then” statement summarizing the…
  • Figure 1: (A) The vector sum C = A + B = B + A. (B) The vector difference A + (−B) = A − B = D. (C, left) A cos θ is the component of A along B and (right) B cos θ is the component of B along A. (D, left) The right-hand rule used to find the direction of E = A × B and (right) the right-hand rule used to find the direction of −E = B × A.
    Mechanics
    Mechanics, science concerned with the motion of bodies under the action of forces, including the special case in which a body remains at rest. Of first concern in the problem of motion are the forces that bodies exert on one another. This leads to the study of such topics as gravitation,…
  • Hubble Space Telescope
    Astronomy
    Astronomy, science that encompasses the study of all extraterrestrial objects and phenomena. Until the invention of the telescope and the discovery of the laws of motion and gravity in the 17th century, astronomy was primarily concerned with noting and predicting the positions of the Sun, Moon, and…
  • flow chart of scientific method
    Scientific method
    Scientific method, mathematical and experimental technique employed in the sciences. More specifically, it is the technique used in the construction and testing of a scientific hypothesis. The process of observing, asking questions, and seeking answers through tests and experiments is not unique to…
  • Big Science
    Big Science, style of scientific research developed during and after World War II that defined the organization and character of much research in physics and astronomy and later in the biological sciences. Big Science is characterized by large-scale instruments and facilities, supported by funding…
  • Science
    Science, any system of knowledge that is concerned with the physical world and its phenomena and that entails unbiased observations and systematic experimentation. In general, a science involves a pursuit of knowledge covering general truths or the operations of fundamental laws. Science is treated…
  • Natural experiment
    Natural experiment, observational study in which an event or a situation that allows for the random or seemingly random assignment of study subjects to different groups is exploited to answer a particular question. Natural experiments are often used to study situations in which controlled…
  • Copernican system
    Scientific Revolution
    Scientific Revolution, drastic change in scientific thought that took place during the 16th and 17th centuries. A new view of nature emerged during the Scientific Revolution, replacing the Greek view that had dominated science for almost 2,000 years. Science became an autonomous discipline,…
  • Earth's Place in the Universe. Introduction: The History of the Solar System. Aristotle's Philosophical Universe. Ptolemy's Geocentric Cosmos. Copernicus' Heliocentric System. Kepler's Laws of Planetary Motion.
    History of science
    History of science, the development of science over time. On the simplest level, science is knowledge of the world of nature. There are many regularities in nature that humankind has had to recognize for survival since the emergence of Homo sapiens as a species. The Sun and the Moon periodically…
  • invertebrate: nervous system
    Nervous system
    Nervous system, organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. All living organisms are able to detect changes within themselves and in their environments. Changes in the external…
  • Simulation
    Simulation, in industry, science, and education, a research or teaching technique that reproduces actual events and processes under test conditions. Developing a simulation is often a highly complex mathematical process. Initially a set of rules, relationships, and operating procedures are …
  • flow chart of scientific method
    Hypothesis
    Hypothesis, something supposed or taken for granted, with the object of following out its consequences (Greek hypothesis, “a putting under,” the Latin equivalent being suppositio). In planning a course of action, one may consider various alternatives, working out each in detail. Although the word…
  • epilepsy
    Nervous system disease
    Nervous system disease, any of the diseases or disorders that affect the functioning of the human nervous system. Everything that humans sense, consider, and effect and all the unlearned reflexes of the body depend on the functioning of the nervous system. The skeleton and muscles support and…
  • striated muscle; human biceps muscle
    Muscle
    Muscle, contractile tissue found in animals, the function of which is to produce motion. Movement, the intricate cooperation of muscle and nerve fibres, is the means by which an organism interacts with its environment. The innervation of muscle cells, or fibres, permits an animal to carry out the…
  • Figure 1: Data in the table of the Galileo experiment. The tangent to the curve is drawn at t = 0.6.
    Principles of physical science
    Principles of physical science, the procedures and concepts employed by those who study the inorganic world. Physical science, like all the natural sciences, is concerned with describing and relating to one another those experiences of the surrounding world that are shared by different observers…
  • Weeping willow (Salix babylonica).
    Plant
    Plant, (kingdom Plantae), any multicellular eukaryotic life-form characterized by (1) photosynthetic nutrition (a characteristic possessed by all plants except some parasitic plants and underground orchids), in which chemical energy is produced from water, minerals, and carbon dioxide with the aid…
  • The Compact Muon Solenoid magnet arriving in the Large Hadron Collider at CERN, 2007.
    Physical science
    Physical science, the systematic study of the inorganic world, as distinct from the study of the organic world, which is the province of biological science. Physical science is ordinarily thought of as consisting of four broad areas: astronomy, physics, chemistry, and the Earth sciences. Each of…
  • A series of photographs of the Grinnell Glacier taken from the summit of Mount Gould in Glacier National Park, Montana, in 1938, 1981, 1998, and 2006 (from left to right). In 1938 the Grinnell Glacier filled the entire area at the bottom of the image. By 2006 it had largely disappeared from this view.
    Climate change
    Climate change, periodic modification of Earth’s climate brought about as a result of changes in the atmosphere as well as interactions between the atmosphere and various other geologic, chemical, biological, and geographic factors within the Earth system. The atmosphere is a dynamic fluid that is…
  • A diagram shows the position of Earth at the beginning of each season in the Northern Hemisphere.
    Climate
    Climate, conditions of the atmosphere at a particular location over a long period of time; it is the long-term summation of the atmospheric elements (and their variations) that, over short time periods, constitute weather. These elements are solar radiation, temperature, humidity, precipitation…
  • mitochondria and cellular respiration
    Metabolism
    Metabolism, the sum of the chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material. Living organisms are unique in that they can extract energy from their environments and use it to carry out…
  • Anthropocene Epoch
    Anthropocene Epoch
    Anthropocene Epoch, unofficial interval of geologic time, making up the third worldwide division of the Quaternary Period (2.6 million years ago to the present), characterized as the time in which the collective activities of human beings (Homo sapiens) began to substantially alter Earth’s surface,…
  • crystal bonding
    Chemical bonding
    Chemical bonding, any of the interactions that account for the association of atoms into molecules, ions, crystals, and other stable species that make up the familiar substances of the everyday world. When atoms approach one another, their nuclei and electrons interact and tend to distribute…
  • Scientific theory
    Scientific theory, systematic ideational structure of broad scope, conceived by the human imagination, that encompasses a family of empirical (experiential) laws regarding regularities existing in objects and events, both observed and posited. A scientific theory is a structure suggested by these…
  • Figure 1: Energy states in molecular systems (see text).
    Radiation
    Radiation, flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and X rays. All matter is constantly bombarded with radiation of both types from cosmic and terrestrial sources. This article delineates the properties and behaviour of radiation…
  • The transformation of a circular region into an approximately rectangular regionThis suggests that the same constant (π) appears in the formula for the circumference, 2πr, and in the formula for the area, πr2. As the number of pieces increases (from left to right), the “rectangle” converges on a πr by r rectangle with area πr2—the same area as that of the circle. This method of approximating a (complex) region by dividing it into simpler regions dates from antiquity and reappears in the calculus.
    Analysis
    Analysis, a branch of mathematics that deals with continuous change and with certain general types of processes that have emerged from the study of continuous change, such as limits, differentiation, and integration. Since the discovery of the differential and integral calculus by Isaac Newton and…
  • STEM
    STEM, field and curriculum centred on education in the disciplines of science, technology, engineering, and mathematics (STEM). The STEM acronym was introduced in 2001 by scientific administrators at the U.S. National Science Foundation (NSF). The organization previously used the acronym SMET when…
  • The Royal Society's Copley Medal (obverse), bearing the likeness of the award's bequeather, Sir Godfrey Copley, 2nd Baronet (c. 1653–1709).
    Copley Medal
    Copley Medal, the most prestigious scientific award in the United Kingdom, given annually by the Royal Society of London “for outstanding achievements in research in any branch of science.” The Copley Medal is named for Sir Godfrey Copley, 2nd Baronet (c. 1653–1709), a member of the Royal Society…
  • Babylonian mathematical tablet.
    Mathematics
    Mathematics, the science of structure, order, and relation that has evolved from elemental practices of counting, measuring, and describing the shapes of objects. It deals with logical reasoning and quantitative calculation, and its development has involved an increasing degree of idealization and…
  • To understand and explain the complex behaviour of Earth's climate, modern climate models incorporate several variables that stand in for materials passing through Earth's atmosphere and oceans and the forces that affect them.
    Scientific modeling
    Scientific modeling, the generation of a physical, conceptual, or mathematical representation of a real phenomenon that is difficult to observe directly. Scientific models are used to explain and predict the behaviour of real objects or systems and are used in a variety of scientific disciplines,…
  • Mass extinction event
    extinction: Mass extinctions:…
  • Your preference has been recorded
    Check out Britannica's new site for parents!
    Subscribe Today!