Nature

Nature, in the broadest sense, is equivalent to the natural world, physical universe, material world or material universe. "Nature" refers to the phenomena of the physical world, and also to life in general. The term generally does not include manufactured objects and human interaction unless qualified in ways such as, e.g., "human nature" or "the whole of nature". Nature is also generally distinguished from the spiritual or supernatural. It ranges in scale from the subatomic to the galactic.

The word "nature" derives from the Latin word natura, or "the course of things, natural character."www.etymologyonline.com ( Natura was a Latin translation of the Greek word physis (φύσις), which originally related to the innate way in which plants and animals grow of their own accord, and to the Greek word for plants generally. The first known use of physis is in Homer's Iliad, in reference to the intrinsic qualities of a plant. Later uses expanded to the "inherent" or "innate" character of things in general. The concept of nature as a whole, the physical universe, is a more recent development that gained increasingly wide use with the advent of modern scientific method in the last several centuries.Isaac Newton's Philosophiae Naturalis Principia Mathematica (1687), for example, is translated "Mathematical Principles of Natural Philosophy", and reflects the then-current use of the words "natural philosophy", akin to "systematic study of nature".The etymology of the word "physical" shows its use as a synonym for "natural" in about the mid-15th century: [http://www.etymonline.com/index.php?term=physical

In casual speech today, "nature" may refer to the general realm of various types of living plants and animals, and in some cases to the processes associated with inanimate objects – the way that particular types of things exist and change. It is often taken to mean the "natural environment" or wilderness – wild animals, rocks, forest, beaches, and in general those things which have not been substantially altered by human intervention. This more traditional concept of natural things which that can still be found in casual speech implies a distinction between the natural and the artificial, with the latter being understood as that which has been brought into being by a human or human-like consciousness or mind.

Earth

Main article: Earth.

Earth (or, "The Earth") is the fifth largest planet in the solar system, third in order of distance from the Sun. It is the largest of its planetary system's terrestrial planets and the only place in the universe currently known to support life.

The most prominent features of the earth's climate are its two large polar regions, two narrow temperate zones (the most habitable parts of which are in the Northern Hemisphere), and a wide equatorial tropical to subtropical region. Precipitation patterns vary widely, ranging from several meters of water per year to less than a millimeter. Ocean currents are important factors in determining climate, particularly the massive underwater thermohaline circulation which distributes heat energy from the equatorial oceans to the polar regions. About 70% of the surface is covered in salt water oceans, and the remainder consists of continents and islands.

Earth has evolved through geological and biological processes that have left traces of the original conditions. The outer surface is divided into several tectonic plates that gradually migrate across the surface over geologic time spans, which at least several times have changed relatively quickly. The interior of the planet remains active, with a thick layer of molten Earth mantle and an iron-filled core that generates a magnetic field. The atmospheric conditions have been significantly 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 according to latitude and other geographic factors, the long-term average global climate is quite finely regulated, and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.

Based on the available evidence, scientists have been able to reconstruct detailed information about the planet's past. Earth is believed to have formed around 4.5 billion years ago out of the solar nebula, along with the Sun and other planets.G.B. Dalrymple, 1991, "The Age of the Earth", Stanford University Press, California, ISBN 0-8047-1569-6. The moon formed relatively soon afterwards (about 20 million years later, or 4.3 billion years ago). Initially molten, the outer layer of the planet cooled, resulting in the solid crust. Outgassing and volcanic activity produced the primordial atmosphere; condensing water vapor, augmented by ice delivered by comets, produced the oceans.A. Morbidelli et al, 2000, "Source Regions and Time Scales for the Delivery of Water to Earth", Meteoritics & Planetary Science, vol. 35, no. 6, pp. 1309-1320. The highly energetic chemistry is believed to have produced a self-replicating molecule around 4 billion years ago.

Continents formed, then broke up and reformed as the surface of Earth reshaped itself over the course of hundreds of millions of years, occasionally combining to form a supercontinent. Roughly 750 million years ago, the earliest known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia which broke apart about 540 million years ago, then finally Pangaea, which broke apart about 180 million years ago.J.B. Murphy, R.D. Nance, "How do supercontinents assemble?", American Scentist, vol. 92, pp. 324-333. Since the 1960s it has been hypothesized that a severe glacial action during the Neoproterozoic era covered much of the planet in a sheet of ice. This hypothesis has been termed the "Snowball Earth", and it is of particular interest as it precedes the Cambrian explosion in which multi-cellular lifeforms began to widely proliferate the Earth about 530-540 million years ago. J.L. Kirschvink, 1992, "Late Proterozoic Low-Latitude Global Glaciation: The Snowball Earth", The Proterozoic Biosphere, pp 51-52.

Since the Cambrian explosion there have been five distinctly identifiable mass extinctions.D. Raup & J. Sepkoski, 1982, "Mass extinctions in the marine fossil record", Science, vol. 215, pp. 1501–1503. The last mass extinction occurred some 65 million years ago, when a meteorite collision probably triggered the extinction of the non-avian dinosaurs and other large reptiles, but spared small animals such as mammals, which then resembled shrews. Over the last 65 million years, mammalian life diversified.See, e.g., Margulis, Lynn, & Sagan, Dorion. What is Life? (1995) 145 ff.

Several million years ago, a species of small African ape gained the ability to stand upright.Margulis, Lynn & Sagan, Dorion. What is Life? (Weidenfeld and Nicolson, 1995) The subsequent advent of human life, and the development of agriculture and further civilization allowed humans to affect the Earth in a relatively short timespan like no other life form had before, affecting both the nature and quantity of other life forms as well as global climate.

Life

Main article: Life.

Main article: Biosphere.

The advent of photosynthesis in very basic forms of plant life worldwide allowed the sun's energy to be harvested to create conditions allowing for more complex life. The resultant oxygen accumulated in the atmosphere and gave rise to the ozone layer. The incorporation of smaller cells within larger ones resulted in the development of yet more complex cells called eukaryotes.L. V. Berkner, L. C. Marshall, 1965, "On the Origin and Rise of Oxygen Concentration in the Earth's Atmosphere", Journal of the Atmospheric Sciences, Vol. 22, No. 3, pp. 225–261. Cells within colonies became increasingly specialized, resulting in true multicellular organisms. With the ozone layer absorbing harmful ultraviolet radiation, life colonized the surface of Earth.

Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction. Life may also be said to be simply the characteristic state of organisms. Properties common to terrestrial organisms (plants, animals, fungi, protists and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce. An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made analogs of life may also be considered to be life.

The biosphere is the part of Earth's outer shell — including air, land, surface rocks and water — within which life occurs, and which biotic processes in turn alter or transform. From the broadest geophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere (rocks), hydrosphere (water), and atmosphere (air). Currently the entire Earth contains over 75 billion tons (150 trillion pounds or about 6.8 x10¹³ kg) of biomass (life), which lives within various environments within the biosphere.Estimates which include the total amount of dead or inactive plant and animal matter, or "dry biomass", range to 1250 billion tons (about 1100 billion metric tonnes) or more. This does not include estimates of the amount of fossil fuels which were once biotic, but have been converted into their present form by extreme heat and pressure. Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence.Peter V. Sengbusch. "The Flow of Energy in Ecosystems - Productivity, Food Chain, and Trophic Level", University of Hamburg Department of Biology page at More than 1.5 million species of plant and animal life have been identified to date, and estimates of the actual number of existing species range from several million to well over 50 million.Wolosz, Thomas. Just_How_Many_Species_Are_There,_Anyway? Society For Conservation Biology. 26 May 20. The number of individual species of life is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis.See, e.g., Withers, Mark A. et al: "Changing Patterns in the Number of Species in North American Floras" ^*"Tropical" target="_blank" >Scientists Find Fewer Species Than Expected." Science 11 November 2005: Vol. 310. no. 5750, pp. 1029 - 1031 DOI: 10.1126/science.1117682 ^*Wlicox," target="_blank" >Bruce. "Amphibian Decline: More Support for Biocomplexity as a Research Paradigm" ^*

The distinction between plant and animal life is not sharply drawn, with some categories of life that stand between or across the two. Originally Aristotle divided all living things between plants, which generally do not move, and animals. In Linnaeus' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Bacterial life is sometimes included in flora,^*^*. and some classifications use the term bacterial flora separately from plant flora.

Among the many ways of classifying plants are by regional floras, which depending on the purpose of study can also include plant life of an historic era as in fossil flora. Many regions and countries take great pride in their individual arrays of characteristic flora, which can vary widely across the globe due to differences in climate and geography. Regional floras commonly are divided into categories such as native flora and agricultural and garden flora, the latter of which are intentionally grown and cultivated. Some types of "native flora" may actually have been introduced centuries ago by people migrating from one region or continent to another, and become an integral part of the native, or natural flora of the place to which they were introduced. Another category of plant has historically been carved out for weeds. Though the term has fallen into disfavor among botanists as a formal way to categorize "useless" plants, the informal use of the word "weeds" to describe those plants that are deemed worthy of elimination is illustrative of the general tendency of people and societies to seek to alter or shape the course of nature. Similarly, animals are often categorized in ways such as domestic, farm animals, wild animals, pests, etc. according to their relationship to human life.

Animals as a category have several characteristics that generally set them apart from other living things, though they is not traced by scientists to having legs or wings instead of roots and leaves. Animals are eukaryotic and usually multicellular (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. With a few exceptions, most notably the sponges (Phylum Porifera), animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and a nervous system, which sends and processes signals. There is also typically an internal digestive chamber. The eukaryotic cells possessed by all animals are surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms like plants and fungi have cells held in place by cell walls, and so develop by progressive growth.

Although humans currently comprise less than one-tenth of one-percent of the total biomass on Earth, human impact on nature is disproportionately large. Because of the extent of human influence, the boundaries between what we regard as nature and "made environments" is not clearcut except at the extremes. Even at the extremes, the amount of natural environment that is free of discernible human influence is presently diminishing at an increasingly rapid pace, or according to some, has already disappeared.

Ecosystems

Main article: Ecology.

Main article: Ecosystem.

All forms of life are highly interactive with the environment in which they exist, and also with other life forms. In the 20th Century this premise gave rise to the concept of ecosystems. Ecosystems are composed of a variety of abiotic and biotic components that function in an interrelated way.^* Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms. Each living organism has an ongoing and continual relationship with every other element that makes up its environment. An ecosystem can be defined as any situation where there is interaction between organisms and their environment. An ecosystem is composed of two entities, the entirety of life in a given ecosystem, known as the biocoenosis, and the medium in which that life exists, the biotope or habitat. Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves and with their environment.

The concept of an ecosystem can apply to units of variable size, such as a pond, a field, or a piece of deadwood. A unit of smaller size is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. A macroecosystem might involve a whole ecoregion, with its drainage basin.Bailey, Robert C. "Identifying Ecoregion Boundaries", in Environmental Management 34: S14-S26, 2005. (Also published at U.S. Forest Service website ([http://www.fs.fed.us/institute/news_info/Identifying_ecoregion_boundaries.pdf). Ecosystems are often classified by reference to the biotopes concerned. The following ecosystems may be defined:

As "continental ecosystems", such as "forest ecosystems", "meadow ecosystems" such as steppes or savannas), or agro-ecosystems
As ecosystems of inland waters, such as lentic ecosystem"s such as lakes or ponds; or lotic ecosystems such as rivers
As oceanic ecosystems.

Another classification can be done by reference to its communities, such as in the case of an human ecosystem. The broadest classification, today under wide study and analysis, and also subject to widespread arguments about its nature and validity, is that of the entire sum of life seen as analogous to a self-sustaining organism, known as the Gaia theory.

Wilderness

Main article: Wilderness.

Main article: Natural environment.

Wilderness is generally defined as a natural environment on Earth that has not been directly modified by human activity. Ecologists consider wilderness areas to be an integral part of the planet's self-sustaining natural ecosystem (the biosphere).

The word, "wilderness", derives from the notion of wildness; in other words that which is not controllable by humans. The word's etymology is from the Old English wildeornes, which in turn derives from wildeor meaning wild beast (wild + deor = beast, deer)."Wilderness", in The Collins English Dictionary (2000) From this point of view, it is the wildness of a place that makes it a wilderness. The mere presence or activity of people does not disqualify an area from being "Wilderness." Many ecosystems that are, or have been, inhabited or influenced by activities of people may still be considered "wild." This way of looking at wilderness includes areas within which natural processes operate without very noticeable human interference.

Looked at through the lens of the visual arts, nature and wildness have been important subjects in various epochs of world history. An early tradition of landscape art occurred in the Tang Dynasty (618-907). The tradition of representing nature as it is became one of the aims of Chinese painting and was a significant influence in Asian art. Artists learned to depict mountains and rivers “from the perspective of nature as a whole and on the basis of their understanding of the laws of nature… as if seen through the eyes of a bird.” In the 13th century, Shih Erh Chi listed "scenes lacking any places made inaccessible by nature,” as one of the twelve things to avoid in painting. Chinese brush painting Asia-art.net Accessed: May 20, 2006.

The idea of wilderness having intrinsic value emerged in the Western world in the 1800s. British artists John Constable and JMW Turner turned their attention to capturing the beauty of the natural world in their paintings. Prior to that, paintings had been primarily of religious scenes or of human beings. William Wordsworth’s poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increasingly the valuing of nature became an aspect of Western culture. History of Conservation BC Spaces for Nature. Accessed: May 20, 2006.

Beauty in nature

Beauty in nature is a common theme in modern life and in art, and books emphasizing beauty in nature fill large sections of libraries and bookstores. That nature has been depicted and celebrated by so much art, photography, poetry and other literature shows the strength with which many people associate nature and beauty. Why this association exists, and what the association consists of, is studied by the branch of philosophy called aesthetics. Beyond certain basic characteristics agreed by many philosophers to explain what is seen as beautiful, the opinions are virtually endless.For an example of a range of opinions, see and Ralph Waldo Emerson's analysis of the subject at [http://www.emersoncentral.com/beauty.htm

Many scientists, who study nature in more specific and organized ways, also share the conviction that nature is beautiful; the French mathematician, Jules Henri Poincaré (1854-1912) said:

"The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living. Of course I do not here speak of that beauty that strikes the senses, the beauty of quality and appearances; not that I undervalue such beauty, far from it, but it has nothing to do with science; I mean that profounder beauty which comes from the harmonious order of the parts, and which a pure intelligence can grasp." Quoted in, Flake, Gary William: The Computational Beauty of Nature, 1998.

A common classical idea of beautiful art involves the word mimesis, the imitation of nature. Also in the realm of ideas about beauty in nature is that the perfect is implied through symmetry, equal division, and other perfect mathematical forms and notions.

Matter and energy

Main article: Matter.

Main article: Physics.

Some fields of science see nature as "matter in motion", obeying certain "laws of nature" which science seeks to understand. For this reason the most fundamental science is generally understood to be "physics" - the name for which is still recognizable as meaning that it is the study of nature. Matter is commonly defined as the substance of which physical objects are composed. It constitutes the observable Universe. According to the theory of relativity there is no unchangeable distinction between matter and energy, because matter can be converted to energy (see annihilation), and vice versa (see matter creation).

Nature beyond Earth

Main article: Outer space.

Main article: Universe.

Outer space, also simply called space, refers to the relatively empty regions of the Universe outside the atmospheres of celestial bodies. Outer space is used to distinguish it from airspace (and terrestrial locations). There is no discrete boundary between the Earth's atmosphere and space as the atmosphere gradually attenuates with increasing altitude. Outer space within the solar system is called interplanetary space, which passes over into interstellar space at what is known as the heliopause.

Although outer space is certainly spacious, it is far from empty. Outer space is sparsely filled with several dozen organic molecules discovered to date by microwave spectroscopy, blackbody radiation left over from the big bang and the origin of the Universe, and cosmic rays, which include ionized atomic nuclei and various subatomic particles. There is also some gas, plasma and dust, and small meteors. Additionally, there are signs of human life in outer space today, such as material left over from previous manned and unmanned launches which are a potential hazard to space craft. Some of this debris re-enters the atmosphere periodically.

Notes and references

External links

The Essence of Nature Magazine - An online magazine dedicated to nature, animals, and the environment.
The Nature Conservancy - a charitable organization devoted to preserving natural diversity worldwide
English Nature UK government organization devoted to preserving natural diversity in the UK
Nature Detectives An online research and education project for under 18s in the UK
A Guide to Nature and Wildlife Conservation
Nature (1869-1875) This collection of Nature provides insight into the developments and achievements of science at the end of the nineteenth century.

Environmental science | Nature

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