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51-434: Although the term fluid generally includes both the liquid and gas phases, its definition varies among branches of science . Definitions of solid vary as well, and depending on field, some substances can have both fluid and solid properties. Non-Newtonian fluids like Silly Putty appear to behave similar to a solid when a sudden force is applied. Substances with a very high viscosity such as pitch appear to behave like

102-506: A Lagrangian formulation , which allows the techniques used in field theory , in particular, quantization , to be applied to fluids. Perfect fluids are used in general relativity to model idealized distributions of matter , such as the interior of a star or an isotropic universe. In the latter case, the equation of state of the perfect fluid may be used in Friedmann–Lemaître–Robertson–Walker equations to describe

153-418: A wide number of fields . There is also a discipline called mathematical statistics , which is concerned with the theoretical basis of the subject. The word statistics , when referring to the scientific discipline, is singular, as in "Statistics is an art." This should not be confused with the word statistic , referring to a quantity (such as mean or median ) calculated from a set of data, whose plural

204-444: A degree of autonomy as practitioners from various disciplines share in its aims and methods. Applied science is the use of existing scientific knowledge to achieve practical goals, like technology or inventions. Within natural science , disciplines that are basic science develop basic information to explain and perhaps predict phenomena in the natural world. Applied science is the use of scientific processes and knowledge as

255-460: A generalization of systems science . The term originates from Bertalanffy 's General System Theory (GST) and is used in later efforts in other fields, such as the action theory of Talcott Parsons and the sociological autopoiesis of Niklas Luhmann . In this context the word systems is used to refer specifically to self-regulating systems, i.e. that are self-correcting through feedback . Self-regulating systems are found in nature, including

306-452: A solid (see pitch drop experiment ) as well. In particle physics , the concept is extended to include fluidic matters other than liquids or gases. A fluid in medicine or biology refers to any liquid constituent of the body ( body fluid ), whereas "liquid" is not used in this sense. Sometimes liquids given for fluid replacement , either by drinking or by injection, are also called fluids (e.g. "drink plenty of fluids"). In hydraulics , fluid

357-477: A solid, shear stress is a function of strain , but in a fluid, shear stress is a function of strain rate . A consequence of this behavior is Pascal's law which describes the role of pressure in characterizing a fluid's state. The behavior of fluids can be described by the Navier–Stokes equations —a set of partial differential equations which are based on: The study of fluids is fluid mechanics , which

408-411: Is statistics ("this statistic seems wrong" or "these statistics are misleading"). Systems theory is the transdisciplinary study of systems in general, to elucidate principles that can be applied to all types of systems in all fields of research. The term does not yet have a well-established, precise meaning, but systems theory can reasonably be considered a specialization of systems thinking and

459-433: Is a branch of biology concerning interactions among organisms and their biophysical environment , which includes both biotic and abiotic components. Topics of interest include the biodiversity , distribution, biomass , and populations of organisms, as well as cooperation and competition within and between species . Ecosystems are dynamically interacting systems of organisms , the communities they make up, and

510-604: Is a sub-discipline of both biology and chemistry, and from a reductionist point of view it is fundamental in biology. Biochemistry is closely related to molecular biology , cell biology , genetics , and physiology . Microbiology is the study of microorganisms , those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology , bacteriology , protistology , mycology , immunology and parasitology . Botany , also called plant science(s) , plant biology or phytology ,

561-844: Is a subset of general computer science and mathematics that focuses on more mathematical topics of computing, and includes the theory of computation . It is difficult to circumscribe the theoretical areas precisely. The ACM 's (Association for Computing Theory) Special Interest Group on Algorithms and Computation Theory (SIGACT) provides the following description: TCS covers a wide variety of topics including algorithms , data structures , computational complexity , parallel and distributed computation, probabilistic computation , quantum computation , automata theory , information theory , cryptography , program semantics and verification , machine learning , computational biology , computational economics , computational geometry , and computational number theory and algebra . Work in this field

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612-971: Is a term which refers to liquids with certain properties, and is broader than (hydraulic) oils. Fluids display properties such as: These properties are typically a function of their inability to support a shear stress in static equilibrium . By contrast, solids respond to shear either with a spring-like restoring force —meaning that deformations are reversible—or they require a certain initial stress before they deform (see plasticity ). Solids respond with restoring forces to both shear stresses and to normal stresses , both compressive and tensile . By contrast, ideal fluids only respond with restoring forces to normal stresses, called pressure : fluids can be subjected both to compressive stress—corresponding to positive pressure—and to tensile stress, corresponding to negative pressure . Solids and liquids both have tensile strengths, which when exceeded in solids creates irreversible deformation and fracture, and in liquids cause

663-410: Is alternatively known as biology , and physical science is subdivided into branches: physics , chemistry , astronomy and Earth science . These branches of natural science may be further divided into more specialized branches (also known as fields). Physical science is an encompassing term for the branches of natural science that study non-living systems, in contrast to the life sciences. However,

714-409: Is an academic field which is primarily concerned with analysis , collection, classification , manipulation, storage, retrieval , movement, dissemination , and protection of information . Practitioners within and outside the field study the application and the usage of knowledge in organizations in addition to the interaction between people, organizations, and any existing information systems with

765-458: Is disagreement on whether the formal sciences actually constitute as a science. Methods of the formal sciences are, however, essential to the construction and testing of scientific models dealing with observable reality, and major advances in formal sciences have often enabled major advances in the empirical sciences . Logic (from Greek : λογική , logikḗ , 'possessed of reason , intellectual , dialectical , argumentative ')

816-512: Is often distinguished by its emphasis on mathematical technique and rigor . Natural science is a branch of science concerned with the description, prediction, and understanding of natural phenomena , based on empirical evidence from observation and experimentation . Mechanisms such as peer review and repeatability of findings are used to try to ensure the validity of scientific advances. Natural science can be divided into two main branches: life science and physical science . Life science

867-544: Is subdivided into fluid dynamics and fluid statics depending on whether the fluid is in motion. Depending on the relationship between shear stress and the rate of strain and its derivatives , fluids can be characterized as one of the following: Newtonian fluids follow Newton's law of viscosity and may be called viscous fluids . Fluids may be classified by their compressibility: Newtonian and incompressible fluids do not actually exist, but are assumed to be for theoretical settlement. Virtual fluids that completely ignore

918-399: Is the natural science that studies life such as microorganisms , plants , and animals including human beings , – including their physical structure , chemical processes , molecular interactions , physiological mechanisms , development , and evolution . Despite the complexity of the science, certain unifying concepts consolidate it into a single, coherent field. Biology recognizes

969-711: Is the science of plant life and a branch of biology . Traditionally, botany has also included the study of fungi and algae by mycologists and phycologists respectively, with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress . Nowadays, botanists (in the strict sense) study approximately 410,000 species of land plants of which some 391,000 species are vascular plants (including approximately 369,000 species of flowering plants ), and approximately 20,000 are bryophytes . Zoology ( / z oʊ ˈ ɒ l ə dʒ i / )

1020-467: Is the branch of Earth science that studies the ocean. It covers a wide range of topics, including marine organisms and ecosystem dynamics; ocean currents , waves , and geophysical fluid dynamics; plate tectonics and the geology of the seafloor; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries. These diverse topics reflect multiple disciplines that oceanographers blend to further knowledge of

1071-799: Is the branch of biology that studies the animal kingdom, including the structure , embryology , evolution , classification , habits , and distribution of all animals , both living and extinct , and how they interact with their ecosystems. The term is derived from Ancient Greek ζῷον, zōion , i.e. " animal " and λόγος, logos , i.e. "knowledge, study". Some branches of zoology include: anthrozoology , arachnology , archaeozoology , cetology , embryology , entomology , helminthology , herpetology , histology , ichthyology , malacology , mammalogy , morphology , nematology , ornithology , palaeozoology , pathology , primatology , protozoology , taxonomy , and zoogeography . Ecology (from Greek : οἶκος , "house", or "environment"; -λογία , "study of")

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1122-605: Is the closest known substance to a perfect fluid. In classical mechanics , ideal fluids are described by Euler equations . Ideal fluids produce no drag according to d'Alembert's paradox . In space-positive metric signature tensor notation, the stress–energy tensor of a perfect fluid can be written in the form where U is the 4-velocity vector field of the fluid and where η μ ν = diag ⁡ ( − 1 , 1 , 1 , 1 ) {\displaystyle \eta _{\mu \nu }=\operatorname {diag} (-1,1,1,1)}

1173-473: Is the general analysis of nature , conducted in order to understand how the universe behaves. Physics is one of the oldest academic disciplines , perhaps the oldest through its inclusion of astronomy . Over the last two millennia, physics was a part of natural philosophy along with chemistry , certain branches of mathematics , and biology , but during the Scientific Revolution in

1224-466: Is the metric tensor of Minkowski spacetime . In time-positive metric signature tensor notation, the stress–energy tensor of a perfect fluid can be written in the form where U is the 4-velocity of the fluid and where η μ ν = diag ⁡ ( 1 , − 1 , − 1 , − 1 ) {\displaystyle \eta _{\mu \nu }=\operatorname {diag} (1,-1,-1,-1)}

1275-399: Is the metric tensor of Minkowski spacetime . This takes on a particularly simple form in the rest frame where ρ e = ρ m c 2 {\displaystyle \rho _{\text{e}}=\rho _{\text{m}}c^{2}} is the energy density and p {\displaystyle p} is the pressure of the fluid. Perfect fluids admit

1326-436: Is the study of the collection, organization, and interpretation of data . It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments . A statistician is someone who is particularly well versed in the ways of thinking necessary for the successful application of statistical analysis. Such people have often gained this experience through working in any of

1377-436: Is the systematic study of valid rules of inference , i.e. the relations that lead to the acceptance of one proposition (the conclusion ) on the basis of a set of other propositions ( premises ). More broadly, logic is the analysis and appraisal of arguments . It has traditionally included the classification of arguments; the systematic exposition of the logical forms ; the validity and soundness of deductive reasoning ;

1428-479: The cell as the basic unit of life, genes as the basic unit of heredity , and evolution as the engine that propels the creation and extinction of species . Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis . Biochemistry , or biological chemistry , is the study of chemical processes within and relating to living organisms . It

1479-491: The natural sciences as tools for understanding society, and so define science in its stricter modern sense . Interpretivist social scientists, by contrast, may use social critique or symbolic interpretation rather than constructing empirically falsifiable theories. In modern academic practice, researchers are often eclectic , using multiple methodologies (for instance, by combining both quantitative and qualitative research ). The term " social research " has also acquired

1530-551: The solid Earth , the rocks of which it is composed, and the processes by which they change over time. Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon . Modern geology significantly overlaps all other Earth sciences, including hydrology and the atmospheric sciences , and so is treated as one major aspect of integrated Earth system science and planetary science . Oceanography , or marine science ,

1581-513: The solid earth . Typically Earth scientists will use tools from physics , chemistry , biology , geography , chronology and mathematics to build a quantitative understanding of how the Earth system works, and how it evolved to its current state. Geology (from the Ancient Greek γῆ, gē ("earth") and -λoγία, -logia , ("study of", "discourse") ) is an Earth science concerned with

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1632-485: The strength of inductive reasoning ; the study of formal proofs and inference (including paradoxes and fallacies ); and the study of syntax and semantics . Historically, logic has been studied in philosophy (since ancient times) and mathematics (since the mid-19th century). More recently, logic has been studied in cognitive science , which draws on computer science , linguistics , philosophy and psychology , among other disciplines. Information science

1683-507: The 16th century, the natural sciences emerged as unique research programs in their own right. Certain research areas are interdisciplinary , such as biophysics and quantum chemistry , which means that the boundaries of physics are not rigidly defined . In the nineteenth and twentieth centuries physicalism emerged as a major unifying feature of the philosophy of science as physics provides fundamental explanations for every observed natural phenomenon . New ideas in physics often explain

1734-406: The aim of creating, replacing, improving, or understanding the information systems. Mathematics , in the broadest sense, is just a synonym of formal science; but traditionally mathematics means more specifically the coalition of four areas: arithmetic , algebra , geometry , and analysis , which are, to some degree, the study of quantity, structure, space, and change respectively. Statistics

1785-753: The branches of science are summarized by the table Metascience refers to or includes a field of science that is about science itself. OpenAlex and Scholia can be used to visualize and explore scientific fields and research topics. Perfect fluid In physics , a perfect fluid or ideal fluid is a fluid that can be completely characterized by its rest frame mass density ρ m {\displaystyle \rho _{m}} and isotropic pressure p . Real fluids are "sticky" and contain (and conduct) heat. Perfect fluids are idealized models in which these possibilities are ignored. Specifically, perfect fluids have no shear stresses , viscosity , or heat conduction . Quark–gluon plasma

1836-466: The branches of science that are concerned with formal systems , such as logic , mathematics , theoretical computer science , information theory , systems theory , decision theory , statistics . Unlike other branches, the formal sciences are not concerned with the validity of theories based on observations in the real world ( empirical knowledge ), but rather with the properties of formal systems based on definitions and rules . Hence there

1887-413: The composition, behavior (or reaction), structure, and properties of matter , as well as the changes it undergoes during chemical reactions . It is a physical science which studies various substances , atoms , molecules , and matter (especially carbon based). Example sub-disciplines of chemistry include: biochemistry , the study of substances found in biological organisms ; physical chemistry ,

1938-421: The decisions they do. Decision theory is closely related to the field of game theory and is an interdisciplinary topic, studied by economists, statisticians, psychologists, biologists, political and other social scientists, philosophers, and computer. Empirical applications of this rich theory are usually done with the help of statistical and econometric methods. Theoretical computer science ( TCS )

1989-601: The development of the computer in the latter half of the 20th century, breakthroughs in weather forecasting were achieved. Space science is the study of everything in outer space. This has sometimes been called astronomy , but recently astronomy has come to be regarded as a division of broader space science, which has grown to include other related fields, such as studying issues related to space travel and space exploration (including space medicine ), space archaeology and science performed in outer space (see space research ). Life science , also known as biology ,

2040-400: The effects of viscosity and compressibility are called perfect fluids . Branches of science The branches of science , also referred to as sciences , scientific fields or scientific disciplines , are commonly divided into three major groups: Scientific knowledge must be based on observable phenomena and must be capable of being verified by other researchers working under

2091-406: The fundamental mechanisms of other sciences, while opening to new research areas in mathematics and philosophy. Chemistry (the etymology of the word has been much disputed) is the science of matter and the changes it undergoes. The science of matter is also addressed by physics , but while physics takes a more general and fundamental approach, chemistry is more specialized, being concerned by

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2142-443: The geosciences or the Earth sciences ) is an all-embracing term for the sciences related to the planet Earth . It is arguably a special case in planetary science , the Earth being the only known life -bearing planet. There are both reductionist and holistic approaches to Earth sciences. The formal discipline of Earth sciences may include the study of the atmosphere , hydrosphere , lithosphere , and biosphere , as well as

2193-433: The means to achieve a particularly practical or useful result. This includes a broad range of applied science-related fields, including agricultural science , engineering and medicine . Applied science can also apply formal science , such as statistics and probability theory , as in epidemiology . Genetic epidemiology is an applied science applying both biological and statistical methods. The relationships between

2244-448: The non-living components of their environment. Ecosystem processes, such as primary production , pedogenesis , nutrient cycling , and niche construction , regulate the flux of energy and matter through an environment. Organisms with specific life history traits sustain these processes. Social science is the branch of science devoted to the study of societies and the relationships among individuals within those societies. The term

2295-627: The onset of cavitation . Both solids and liquids have free surfaces, which cost some amount of free energy to form. In the case of solids, the amount of free energy to form a given unit of surface area is called surface energy , whereas for liquids the same quantity is called surface tension . In response to surface tension, the ability of liquids to flow results in behaviour differing from that of solids, though at equilibrium both tend to minimise their surface energy : liquids tend to form rounded droplets , whereas pure solids tend to form crystals . Gases , lacking free surfaces, freely diffuse . In

2346-483: The physiological systems of the human body, in local and global ecosystems, and climate. Decision theory (or the theory of choice not to be confused with choice theory ) is the study of an agent's choices. Decision theory can be broken into two branches: normative decision theory, which analyzes the outcomes of decisions or determines the optimal decisions given constraints and assumptions, and descriptive decision theory, which analyzes how agents actually make

2397-488: The same conditions. This verifiability may well vary even within a scientific discipline. Natural, social, and formal science make up the fundamental sciences , which form the basis of interdisciplinarity - and applied sciences such as engineering and medicine . Specialized scientific disciplines that exist in multiple categories may include parts of other scientific disciplines but often possess their own terminologies and expertises . The formal sciences are

2448-417: The study of chemical processes using physical concepts such as thermodynamics and quantum mechanics ; and analytical chemistry , the analysis of material samples to gain an understanding of their chemical composition and structure . Many more specialized disciplines have emerged in recent years, e.g. neurochemistry the chemical study of the nervous system . Earth science (also known as geoscience ,

2499-497: The term "physical" creates an unintended, somewhat arbitrary distinction, since many branches of physical science also study biological phenomena. There is a difference between physical science and physics. Physics (from Ancient Greek : φύσις , romanized :  physis , lit.   'nature') is a natural science that involves the study of matter and its motion through spacetime , along with related concepts such as energy and force . More broadly, it

2550-460: The world ocean and understanding of processes within it: biology , chemistry , geology , meteorology , and physics as well as geography . Meteorology is the interdisciplinary scientific study of the atmosphere . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 17th century. The 19th century saw breakthroughs occur after observing networks developed across several countries. After

2601-431: Was formerly used to refer to the field of sociology , the original "science of society", established in the 19th century. In addition to sociology, it now encompasses a wide array of academic disciplines , including anthropology , archaeology , economics , education , history , human geography , law , linguistics , political science , and psychology . Positivist social scientists use methods resembling those of

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