A mineral is, broadly speaking, a solid chemical compound that occurs in pure form. A rock may consist of a single mineral, or may be an aggregate of two or more different minerals, spacially segregated into distinct phases. Compounds that occur only in living beings are excluded, but some minerals are biogenic and/or are organic compounds in the sense of chemistry. Moreover, living beings synthesize inorganic minerals that occur in rocks. In geology and mineralogy, the term "mineral" is reserved for mineral species: crystalline compounds with a well-defined chemical composition and a specific crystal structure. Minerals without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound may occur with different crystal structures, each structure is considered different mineral species. Thus, for example and stishovite are two different minerals consisting of the same compound, silicon dioxide; the International Mineralogical Association is the world's premier standard body for the definition and nomenclature of mineral species.
As of November 2018, the IMA recognizes 5,413 official mineral species. Out of more than 5,500 proposed or traditional ones; the chemical composition of a named mineral species may vary somewhat by the inclusion of small amounts of impurities. Specific varieties of a species sometimes have official names of their own. For example, amethyst is a purple variety of the mineral species quartz; some mineral species can have variable proportions of two or more chemical elements that occupy equivalent positions in the mineral's structure. Sometimes a mineral with variable composition is split into separate species, more or less arbitrarily, forming a mineral group. Besides the essential chemical composition and crystal structure, the description of a mineral species includes its common physical properties such as habit, lustre, colour, tenacity, fracture, specific gravity, fluorescence, radioactivity, as well as its taste or smell and its reaction to acid. Minerals are classified by key chemical constituents.
Silicate minerals comprise 90% of the Earth's crust. Other important mineral groups include the native elements, oxides, carbonates and phosphates. One definition of a mineral encompasses the following criteria: Formed by a natural process. Stable or metastable at room temperature. In the simplest sense, this means. Classical examples of exceptions to this rule include native mercury, which crystallizes at −39 °C, water ice, solid only below 0 °C. Modern advances have included extensive study of liquid crystals, which extensively involve mineralogy. Represented by a chemical formula. Minerals are chemical compounds, as such they can be described by fixed or a variable formula. Many mineral groups and species are composed of a solid solution. For example, the olivine group is described by the variable formula 2SiO4, a solid solution of two end-member species, magnesium-rich forsterite and iron-rich fayalite, which are described by a fixed chemical formula. Mineral species themselves could have a variable composition, such as the sulfide mackinawite, 9S8, a ferrous sulfide, but has a significant nickel impurity, reflected in its formula.
Ordered atomic arrangement. This means crystalline. An ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been several recent proposals to classify amorphous substances as minerals; the formal definition of a mineral approved by the IMA in 1995: "A mineral is an element or chemical compound, crystalline and, formed as a result of geological processes." Abiogenic. Biogenic substances are explicitly excluded by the IMA: "Biogenic substances are chemical compounds produced by biological processes without a geological component and are not regarded as minerals. However, if geological processes were involved in the genesis of the compound the product can be accepted as a mineral."The first three general characteristics are less debated than the last two. Mineral classification schemes and their definitions are evolving to match recent advances in mineral science. Recent changes have included the addition of an organic class, in both the new Dana and the Strunz classification schemes.
The organic class includes a rare group of minerals with hydrocarbons. The IMA Commission on New Minerals and Mineral Names adopted in 2009 a hierarchical scheme for the naming and classification of mineral groups and group names and established seven commissions and four working groups to review and classify minerals into an official listing of their published names. According to these new r
Natural history is a domain of inquiry involving organisms including animals and plants in their environment. A person who studies natural history is called natural historian. Natural history is not limited to it, it involves the systematic study of any category of natural organisms. So while it dates from studies in the ancient Greco-Roman world and the mediaeval Arabic world, through to European Renaissance naturalists working in near isolation, today's natural history is a cross discipline umbrella of many specialty sciences; the meaning of the English term "natural history" has narrowed progressively with time. In antiquity, "natural history" covered anything connected with nature, or which used materials drawn from nature, such as Pliny the Elder's encyclopedia of this title, published circa 77 to 79 AD, which covers astronomy, geography and their technology and superstition, as well as animals and plants. Medieval European academics considered knowledge to have two main divisions: the humanities and divinity, with science studied through texts rather than observation or experiment.
The study of nature revived in the Renaissance, became a third branch of academic knowledge, itself divided into descriptive natural history and natural philosophy, the analytical study of nature. In modern terms, natural philosophy corresponded to modern physics and chemistry, while natural history included the biological and geological sciences; the two were associated. During the heyday of the gentleman scientists, many people contributed to both fields, early papers in both were read at professional science society meetings such as the Royal Society and the French Academy of Sciences – both founded during the seventeenth century. Natural history had been encouraged by practical motives, such as Linnaeus' aspiration to improve the economic condition of Sweden; the Industrial Revolution prompted the development of geology to help find useful mineral deposits. Modern definitions of natural history come from a variety of fields and sources, many of the modern definitions emphasize a particular aspect of the field, creating a plurality of definitions with a number of common themes among them.
For example, while natural history is most defined as a type of observation and a subject of study, it can be defined as a body of knowledge, as a craft or a practice, in which the emphasis is placed more on the observer than on the observed. Definitions from biologists focus on the scientific study of individual organisms in their environment, as seen in this definition by Marston Bates: "Natural history is the study of animals and Plants – of organisms.... I like to think of natural history as the study of life at the level of the individual – of what plants and animals do, how they react to each other and their environment, how they are organized into larger groupings like populations and communities" and this more recent definition by D. S. Wilcove and T. Eisner: "The close observation of organisms—their origins, their evolution, their behavior, their relationships with other species"; this focus on organisms in their environment is echoed by H. W. Greene and J. B. Losos: "Natural history focuses on where organisms are and what they do in their environment, including interactions with other organisms.
It encompasses changes in internal states insofar as they pertain to what organisms do". Some definitions go further, focusing on direct observation of organisms in their environment, both past and present, such as this one by G. A. Bartholomew: "A student of natural history, or a naturalist, studies the world by observing plants and animals directly; because organisms are functionally inseparable from the environment in which they live and because their structure and function cannot be adequately interpreted without knowing some of their evolutionary history, the study of natural history embraces the study of fossils as well as physiographic and other aspects of the physical environment". A common thread in many definitions of natural history is the inclusion of a descriptive component, as seen in a recent definition by H. W. Greene: "Descriptive ecology and ethology". Several authors have argued for a more expansive view of natural history, including S. Herman, who defines the field as "the scientific study of plants and animals in their natural environments.
It is concerned with levels of organization from the individual organism to the ecosystem, stresses identification, life history, distribution and inter-relationships. It and appropriately includes an esthetic component", T. Fleischner, who defines the field more broadly, as "A practice of intentional, focused attentiveness and receptivity to the more-than-human world, guided by honesty and accuracy"; these definitions explicitly include the arts in the field of natural history, are aligned with the broad definition outlined by B. Lopez, who defines the field as the "Patient interrogation of a landscape" while referring to the natural history knowledge of the Eskimo. A different framework for natural history, covering a similar range of themes, is implied in the scope of work encompassed by many leading natural history museums, which include elements of anthropology, geology and astronomy along with botany and zoology, or include both cultural and natural components of the world; the pl
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They live in compact colonies of many identical individual polyps. Corals species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of myriad genetically identical polyps; each polyp is a sac-like animal only a few millimeters in diameter and a few centimeters in length. A set of tentacles surround a central mouth opening. An exoskeleton is excreted near the base. Over many generations, the colony thus creates a large skeleton characteristic of the species. Individual heads grow by asexual reproduction of polyps. Corals breed sexually by spawning: polyps of the same species release gametes over a period of one to several nights around a full moon. Although some corals are able to catch small fish and plankton using stinging cells on their tentacles, most corals obtain the majority of their energy and nutrients from photosynthetic unicellular dinoflagellates in the genus Symbiodinium that live within their tissues.
These are known as zooxanthellae. Such corals require sunlight and grow in clear, shallow water at depths less than 60 metres. Corals are major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the enormous Great Barrier Reef off the coast of Queensland, Australia. Other corals do not rely on zooxanthellae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3,300 metres; some have been found on the Darwin Mounds, northwest of Cape Wrath and others as far north as off the coast of Washington State and the Aleutian Islands. Aristotle's pupil Theophrastus described the red coral, korallion, in his book on stones, implying it was a mineral, but he described it as a deep-sea plant in his Enquiries on Plants, where he mentions large stony plants that reveal bright flowers when under water in the Gulf of Heroes. Pliny the Elder stated boldly that several sea creatures including sea nettles and sponges "are neither animals nor plants, but are possessed of a third nature".
Petrus Gyllius copied Pliny, introducing the term zoophyta for this third group in his 1535 book On the French and Latin Names of the Fishes of the Marseilles Region. Gyllius further noted, following Aristotle, how hard it was to define what was a plant and what was an animal; the Persian polymath Al-Biruni classified sponges and corals as animals, arguing that they respond to touch. People believed corals to be plants until the eighteenth century, when William Herschel used a microscope to establish that coral had the characteristic thin cell membranes of an animal. Presently, corals are classified as certain species of animals within the sub-classes Hexacorallia and Octocorallia of the class Anthozoa in the phylum Cnidaria. Hexacorallia includes the stony corals and these groups have polyps that have a 6-fold symmetry. Octocorallia includes blue coral and soft corals and species of Octocorallia have polyps with an eightfold symmetry, each polyp having eight tentacles and eight mesenteries.
Fire corals are not true corals. Corals are sessile animals and differ from most other cnidarians in not having a medusa stage in their life cycle; the body unit of the animal is a polyp. Most corals are colonial, the initial polyp budding to produce another and the colony developing from this small start. In stony corals known as hard corals, the polyps produce a skeleton composed of calcium carbonate to strengthen and protect the organism; this is deposited by the coenosarc, the living tissue that connects them. The polyps sit in cup-shaped depressions in the skeleton known as corallites. Colonies of stony coral are variable in appearance. In soft corals, there is no stony skeleton but the tissues are toughened by the presence of tiny skeletal elements known as sclerites, which are made from calcium carbonate. Soft corals are variable in form and most are colonial. A few soft corals are stolonate. In some species this is thick and the polyps are embedded; some soft corals are form lobes. Others have a central axial skeleton embedded in the tissue matrix.
This is composed either of a fibrous protein called gorgonin or of a calcified material. In both stony and soft corals, the polyps can be retracted, with stony corals relying on their hard skeleton and cnidocytes for defence against predators, soft corals relying on chemical defences in the form of toxic substances present in the tissues known as terpenoids; the polyps of stony corals have six-fold symmetry. The mouth of each polyp is surrounded by a ring of tentacles. In stony corals these are cylindrical and taper to a point, but in soft corals they are pinnate with side branches known as pinnules. In some tropical species these are reduced to mere stubs and in some they are fused to give a paddle-like appearance. In most corals, the tentacles are retracted by day and spread out at night to catch plankton and other small organisms. Shallow water species of both stony and soft corals can be zooxanthellate, the corals supplementing their plankton diet with t
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times. Earth's axis of rotation is tilted with respect to its orbital plane; the gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, slows its rotation. Earth is the largest of the four terrestrial planets. Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water by oceans; the remaining 29% is land consisting of continents and islands that together have many lakes and other sources of water that contribute to the hydrosphere.
The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, a convecting mantle that drives plate tectonics. Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms; some geological evidence indicates. Since the combination of Earth's distance from the Sun, physical properties, geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely. Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.
Humans have developed diverse cultures. The modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most spelled eorðe, it has cognates in every Germanic language, their proto-Germanic root has been reconstructed as *erþō. In its earliest appearances, eorðe was being used to translate the many senses of Latin terra and Greek γῆ: the ground, its soil, dry land, the human world, the surface of the world, the globe itself; as with Terra and Gaia, Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus, Norse mythology included Jörð, a giantess given as the mother of Thor. Earth was written in lowercase, from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, the earth became the Earth when referenced along with other heavenly bodies. More the name is sometimes given as Earth, by analogy with the names of the other planets.
House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name but writes it in lowercase when preceded by the, it always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago. By 4.54±0.04 Bya the primordial Earth had formed. The bodies in the Solar System evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, dust. According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 million years to form. A subject of research is the formation of some 4.53 Bya. A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth.
In this view, the mass of Theia was 10 percent of Earth, it hit Earth with a glancing blow and some of its mass merged with Earth. Between 4.1 and 3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity. By 3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. A crust formed; the two models that explain land mass propose either a steady growth to the present-day forms or, more a rapid growth early in Earth history followed by a long-term steady continental area. Continents formed by plate tectonics
Nature, in the broadest sense, is the natural, physical, or material world or universe. "Nature" can refer to the phenomena of the physical world, to life in general. The study of nature is a large, part of science. Although humans are part of nature, human activity is understood as a separate category from other natural phenomena; the word nature is derived from the Latin word natura, or "essential qualities, innate disposition", in ancient times meant "birth". Natura is a Latin translation of the Greek word physis, which related to the intrinsic characteristics that plants and other features of the world develop of their own accord; the concept of nature as a whole, the physical universe, is one of several expansions of the original notion. This usage continued during the advent of modern scientific method in the last several centuries. Within the various uses of the word today, "nature" refers to geology and wildlife. Nature can refer to the general realm of living plants and animals, in some cases to the processes associated with inanimate objects—the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth.
It is taken to mean the "natural environment" or wilderness—wild animals, forest, in general those things that have not been altered by human intervention, or which persist despite human intervention. For example, manufactured objects and human interaction are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature"; this more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that, brought into being by a human consciousness or a human mind. Depending on the particular context, the term "natural" might be distinguished from the unnatural or the supernatural. Earth is the only planet known to support life, its natural features are the subject of many fields of scientific research. Within the solar system, it is third closest to the sun, its most prominent climatic features are its two large polar regions, two narrow temperate zones, a wide equatorial tropical to subtropical region.
Precipitation varies with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the Northern Hemisphere. Earth has evolved through geological and biological processes that have left traces of the original conditions; the outer surface is divided into several migrating tectonic plates. The interior remains active, with a thick layer of plastic mantle and an iron-filled core that generates a magnetic field; this iron core is composed of a solid inner phase, a fluid outer phase. Convective motion in the core generates electric currents through dynamo action, these, in turn, generate the geomagnetic field; the atmospheric conditions have been altered from the original conditions by the presence of life-forms, which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by latitude and other geographic factors, the long-term average global climate is quite stable during interglacial periods, variations of a degree or two of average global temperature have had major effects on the ecological balance, on the actual geography of the Earth.
Geology is the study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, physical properties and history of Earth materials, the processes by which they are formed and changed; the field is a major academic discipline, is important for mineral and hydrocarbon extraction, knowledge about and mitigation of natural hazards, some Geotechnical engineering fields, understanding past climates and environments. The geology of an area evolves through time as rock units are deposited and inserted and deformational processes change their shapes and locations. Rock units are first emplaced either by deposition onto the surface or intrude into the overlying rock. Deposition can occur when sediments settle onto the surface of the Earth and lithify into sedimentary rock, or when as volcanic material such as volcanic ash or lava flows, blanket the surface. Igneous intrusions such as batholiths, laccoliths and sills, push upwards into the overlying rock, crystallize as they intrude.
After the initial sequence of rocks has been deposited, the rock units can be deformed and/or metamorphosed. Deformation occurs as a result of horizontal shortening, horizontal extension, or side-to-side motion; these structural regimes broadly relate to convergent boundaries, divergent boundaries, transform boundaries between tectonic plates. Earth is estimated to have formed 4.54 billion years ago from the solar nebula, along with the Sun and other planets. The moon formed 20 million years later. Molten, the outer layer of the Earth cooled, resulting in the solid crust. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, most or all of which came from ice delivered by comets, produced the oceans and other water sources; the energetic chemistry is believed to have produced a self-replicat
Franz Josef Land
Franz Josef Land, Franz Joseph Land or Francis Joseph's Land is a Russian archipelago, inhabited only by military personnel, located in the Arctic Ocean and constituting the northernmost part of Arkhangelsk Oblast. It consists of 191 islands, which cover an area of 16,134 square kilometers, stretching 375 kilometers from east to west and 234 kilometers from north to south; the islands are categorized in three groups, a western and eastern, separated by the British Channel and the Austrian Strait. The central group is further divided into a southern section by the Markham Strait; the largest island is Prince George Land, which measures 2,741 square kilometers, followed by Wilczek Land, Graham Bell Island and Alexandra Land. Eighty-five percent of the archipelago is glaciated, with large unglaciated areas being located on the largest islands and many of the smallest islands; the islands have a combined coastline of 4,425 kilometers. Compared to other Arctic archipelagos, Franz Joseph Land has a high dissection rate of 3.6 square kilometers per coastline kilometer.
Cape Fligely on Rudolf Island is the northernmost point of the Eastern Hemisphere. The highest elevations are found in the eastern group, with the highest point located on Wilczek Land, 670 meters above mean sea level; the archipelago was first spotted by the Norwegian sealers Nils Fredrik Rønnbeck and Johan Petter Aidijärvi in 1865, although they did not report their finding. The first reported finding was in the 1873 Austro-Hungarian North Pole Expedition led by Julius von Payer and Karl Weyprecht, who named the area after Emperor Franz Joseph I; the islands under the name Fridtjof Nansen Land, were annexed by the Soviet Union in 1926, who settled small outposts for research and military purposes. The Kingdom of Norway rejected several private expeditions were sent to the islands. With the Cold War, the islands became off limits for foreigners and two military airfields were built; the islands have been a nature sanctuary since 1994 and became part of the Russian Arctic National Park in 2012.
There are two candidates for the discovery of Franz Josef Land. The first was the Norwegian sealing vessel Spidsbergen, with captain Nils Fredrik Rønnbeck and harpooner Johan Petter Aidijärvi, they sailed northeast from Svalbard in 1865 searching for suitable sealing sites, they found land, most Franz Josef Land. The account is believed to be factual, but an announcement of the discovery was never made, their sighting therefore remained unknown to subsequent explorers; this was at the time common to keep newly discovered areas secret, as their discovery was aimed at exploiting them for sealing and whaling, exposure would cause competitors to flock to the site. Russian scientist N. G. Schilling proposed in 1865 that the ice conditions in the Barents Sea could only be explained if there was another land mass in the area, but he never received funding for an expedition; the Austro-Hungarian North Pole Expedition of 1872–74 was the first to announce the discovery of the islands. Led by Julius von Payer and Karl Weyprecht of Austria–Hungary on board the schooner Tegetthoff, the expedition's primary goal was to find the Northeast Passage and its secondary goal to reach the North Pole.
Starting in July 1872, the vessel drifted from Novaya Zemlya to a new landmass, which they named in honor of Franz Joseph I, Emperor of Austria. The expedition contributed to the mapping and exploration of the islands; the next expedition to spot the archipelago was the Dutch Expedition for the Exploration of the Barents Sea, on board the schooner Willem Barents. Constrained by the ice, they never reached land. Benjamin Leigh Smith's expedition in 1880, aboard the barque Eira, followed a route from Spitsbergen to Franz Josef Land, landing on Bell Island in August. Leigh Smith explored the vicinity and set up a base at Eira Harbour, before exploring towards McClintock Island, he returned the following year in the same vessel. The explorers were stopped by ice at Cape Flora, Eira sank on 21 August, they built a cottage and stayed the winter, to be rescued by the British vessels Kara and Hope the following summer. These early expeditions concentrated their explorations on the southern and central parts of the archipelago.
Nansen's Fram expedition was an 1893–1896 attempt by the Norwegian explorer Fridtjof Nansen to reach the geographical North Pole by harnessing the natural east–west current of the Arctic Ocean. Departing in 1893, Fram drifted from the New Siberian Islands for one and a half years before Nansen became impatient and set out to reach the North Pole on skies with Hjalmar Johansen, they gave up on reaching the pole and instead found their way to Franz Josef Land, the nearest land known to man. They were thus able to establish. In the meantime the Jackson–Harmsworth Expedition set off in 1894, set up a base on Bell Island, stayed for the winter; the following season they spent exploring. By pure chance, at Cape Flora in the spring of 1896, Nansen stumbled upon Frederick George Jackson, able to transport him back to Norway. Nansen and Jackson explored the northern and western portions of the islands. Once the basic geography of Franz Josef Land had become apparent, expeditions shifted to using the archipelago as a basis to reach the North Pole.
The first such attempt was conducted by the National Geographic Society-sponsored American journalist Walter Wellman in 1898. The two Norwegians, Paul Bjørvig og Bernt Bentsen, stayed the winter 1898-9 at Cape Heller on Wilczek Land, but insufficient fuel caused the l
Natural science is a branch of science concerned with the description 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: physical science. Physical science is subdivided into branches, including physics, chemistry and earth science; these branches of natural science may be further divided into more specialized branches. In Western society's analytic tradition, the empirical sciences and natural sciences use tools from formal sciences, such as mathematics and logic, converting information about nature into measurements which can be explained as clear statements of the "laws of nature"; the social sciences use such methods, but rely more on qualitative research, so that they are sometimes called "soft science", whereas natural sciences, insofar as they emphasize quantifiable data produced and confirmed through the scientific method, are sometimes called "hard science".
Modern natural science succeeded more classical approaches to natural philosophy traced to ancient Greece. Galileo, Descartes and Newton debated the benefits of using approaches which were more mathematical and more experimental in a methodical way. Still, philosophical perspectives and presuppositions overlooked, remain necessary in natural science. Systematic data collection, including discovery science, succeeded natural history, which emerged in the 16th century by describing and classifying plants, minerals, so on. Today, "natural history" suggests observational descriptions aimed at popular audiences. Philosophers of science have suggested a number of criteria, including Karl Popper's controversial falsifiability criterion, to help them differentiate scientific endeavors from non-scientific ones. Validity and quality control, such as peer review and repeatability of findings, are amongst the most respected criteria in the present-day global scientific community; this field encompasses a set of disciplines.
The scale of study can range from sub-component biophysics up to complex ecologies. Biology is concerned with the characteristics and behaviors of organisms, as well as how species were formed and their interactions with each other and the environment; the biological fields of botany and medicine date back to early periods of civilization, while microbiology was introduced in the 17th century with the invention of the microscope. However, it was not until the 19th century. Once scientists discovered commonalities between all living things, it was decided they were best studied as a whole; some key developments in biology were the discovery of genetics. Modern biology is divided into subdisciplines by the type of organism and by the scale being studied. Molecular biology is the study of the fundamental chemistry of life, while cellular biology is the examination of the cell. At a higher level and physiology look at the internal structures, their functions, of an organism, while ecology looks at how various organisms interrelate.
Constituting the scientific study of matter at the atomic and molecular scale, chemistry deals with collections of atoms, such as gases, molecules and metals. The composition, statistical properties and reactions of these materials are studied. Chemistry involves understanding the properties and interactions of individual atoms and molecules for use in larger-scale applications. Most chemical processes can be studied directly in a laboratory, using a series of techniques for manipulating materials, as well as an understanding of the underlying processes. Chemistry is called "the central science" because of its role in connecting the other natural sciences. Early experiments in chemistry had their roots in the system of Alchemy, a set of beliefs combining mysticism with physical experiments; the science of chemistry began to develop with the work of Robert Boyle, the discoverer of gas, Antoine Lavoisier, who developed the theory of the Conservation of mass. The discovery of the chemical elements and atomic theory began to systematize this science, researchers developed a fundamental understanding of states of matter, chemical bonds and chemical reactions.
The success of this science led to a complementary chemical industry that now plays a significant role in the world economy. Physics embodies the study of the fundamental constituents of the universe, the forces and interactions they exert on one another, the results produced by these interactions. In general, physics is regarded as the fundamental science, because all other natural sciences use and obey the principles and laws set down by the field. Physics relies on mathematics as the logical framework for formulation and quantification of principles; the study of the principles of the universe has a long history and derives from direct observation and experimentation. The formulation of theories about the governing laws of the universe has been central to the study of physics from early on, with philosophy yielding to systematic, quantitative experimental testing and observation as the source of verification. Key historical developments in physics include Isaac Newton's theory of universal g