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.
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GedankenexperimentGedankenexperiment, (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… -
Philosophy of sciencePhilosophy 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… -
EvolutionEvolution, 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… -
HeredityHeredity, 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… -
StarStar, 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… -
Space tourismSpace 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… -
Space explorationSpace 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… -
TypologyTypology, 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…
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CellCell, 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 groupControl 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…
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AngiospermAngiosperm, 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… -
Scientific hypothesisScientific 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… -
MechanicsMechanics, 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,… -
AstronomyAstronomy, 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… -
Scientific methodScientific 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 ScienceBig 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…
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ScienceScience, 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…
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Natural experimentNatural 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…
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Scientific RevolutionScientific 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,… -
History of scienceHistory 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… -
Nervous systemNervous 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… -
SimulationSimulation, 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 …
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HypothesisHypothesis, 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…
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Nervous system diseaseNervous 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… -
MuscleMuscle, 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… -
Principles of physical sciencePrinciples 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… -
PlantPlant, (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… -
Physical sciencePhysical 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… -
Climate changeClimate 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… -
ClimateClimate, 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… -
MetabolismMetabolism, 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 EpochAnthropocene 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,… -
Chemical bondingChemical 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 theoryScientific 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…
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RadiationRadiation, 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… -
AnalysisAnalysis, 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… -
STEMSTEM, 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…
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Copley MedalCopley 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… -
MathematicsMathematics, 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… -
Scientific modelingScientific 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 eventextinction: Mass extinctions:…
