Everything about Nature totally explained
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. Manufactured objects and human interaction are not considered part of nature unless qualified in ways such as "
human nature" or "the whole of nature". Nature is generally distinguished from the
supernatural. It ranges in scale from the
subatomic to the
galactic.
The word
nature is derived from the Latin word
natura, or "the course of things, natural character."
Natura was a Latin translation of the Greek word
physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord. This is shown in the first written use of the word φύσις, in connection with a plant. The concept of nature as a whole, the physical
universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socratic philosophers, and has steadily gained currency ever since. This usage was confirmed during the advent of modern
scientific method in the last several centuries.
Within the various uses of the word 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 of their own accord, such as the
weather and
geology of the Earth, and the
matter and
energy of which all these things are composed. It is often taken to mean the "
natural environment" or
wilderness – wild animals, rocks, forest, beaches, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. This more traditional concept of natural things which can still be found today 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.
Etymology
The word
nature means the universe, with all its phenomena.
Natura was a Latin translation of the Greek word
physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord. The word φύσις occurs very early in Greek philosophy, generally in similar senses to those of the modern English word
nature. This is shown in the first written use of the word φύσις, in connection with a plant by
Homer. The concept of nature as a whole, the physical
universe, is one of several expansions of the original notion. This usage was confirmed during the advent of modern
scientific method. Isaac Newton's
Philosophiae Naturalis Principia Mathematica (1687), for example, is translated "Mathematical Principles of Natural Philosophy". The etymology of the word "physical" shows its use as a synonym for "natural" in about the mid-15th century.
Earth
solar system, it's third nearest to the sun; it's the largest
terrestrial planet and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow
temperate zones, and a wide
equatorial
tropical to
subtropical region.
Precipitation varies widely with location, from several
metres of water per year to less than a
millimetre. About 70 percent of the 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 gradually migrating
tectonic plates, which have changed relatively quickly several times. The interior remains active, with a thick layer of molten
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 lifeforms, 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, 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.
Historical perspective
Earth is estimated to have formed 4.55 billion years ago from the
solar nebula, along with the Sun and other planets. The moon formed roughly 20 million years later. 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. 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 over hundreds of millions of years, occasionally combining to make 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.
There is significant evidence, still being discussed among scientists, 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's of particular interest as it precedes the
Cambrian explosion in which multicellular life forms began to proliferate about 530-540 million years ago.
Since the
Cambrian explosion there have been five distinctly identifiable
mass extinctions. 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 past 65 million years, mammalian life diversified.
Several million years ago, a species of small African ape gained the ability to stand upright. The subsequent advent of human life, and the development of agriculture and further
civilization allowed humans to affect the Earth more rapidly than any previous life form, affecting both the nature and quantity of other organisms as well as global climate. By comparison, the
Oxygen Catastrophe, produced by the proliferation of algae during the
Siderian period, required about 300 million years to culminate.)
The present era is classified as part of a mass extinction event, the
Holocene extinction event, the fastest ever to have occurred. Some, such as
E. O. Wilson of
Harvard University, predict that human destruction of the
biosphere could cause the extinction of one-half of all species in the next 100 years. The extent of the current extinction event is still being researched, debated and calculated by biologists.
Atmosphere, climate and weather
The atmosphere of the Earth serves as a key factor in sustaining the planetary
ecosystem. The thin layer of
gases that envelops the Earth is held in place by the planet's gravity. Dry
air consists of 78%
nitrogen, 21%
oxygen, 1%
argon and other
inert gases, carbon dioxide, etc.; but air also contains a variable amount of
water vapor. The atmospheric pressure declines steadily with altitude, and has a
scale height of about 8
kilometres at the Earth's surface: the height at which the atmospheric pressure has declined by a factor of
e (a mathematical constant
equal to 2.71...). The
ozone layer of the Earth's atmosphere plays an important role in depleting the amount of
ultraviolet (UV) radiation that reaches the surface. As
DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.
Terrestrial weather occurs almost exclusively in the
lower part of the atmosphere, and serves as a convective system for redistributing heat. Ocean currents are another important factor in determining climate, particularly the major underwater
thermohaline circulation which distributes heat energy from the equatorial oceans to the polar regions. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the polar regions much colder.
Weather can have both beneficial and harmful effects. Extremes in weather, such as
tornadoes or
hurricanes and
cyclones, can expend large amounts of energy along their paths, and produce devastation. Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals dependent on its growth for their food.
The planetary climate is a measure of the long-term trends in the weather. Various factors are known to
influence the climate, including ocean currents, surface
albedo,
greenhouse gases, variations in the solar luminosity, and changes to the planet's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including
ice ages.
The climate of a region depends on a number of factors, especially
latitude. A latitudinal band of the surface with similar climatic attributes forms a climate region. There are a number of such regions, ranging from the
tropical climate at the equator to the
polar climate in the northern and southern extremes. Weather is also influenced by the
seasons, which result from the
Earth's
axis being
tilted relative to its
orbital plane. Thus, at any given time during the summer or winter, one part of the planet is more directly exposed to the rays of the
sun. This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the
northern and
southern hemispheres experience opposite seasons.
Weather is a
chaotic system that's readily modified by small changes to the
environment, so accurate
weather forecasting is currently limited to only a few days. Overall, two things are currently happening worldwide: (1) temperature is increasing on the average; and (2) regional climates have been undergoing noticeable changes.
Life
Although there's 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,
archaea and
bacteria) are that they're 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 x 10
13 kilograms) of
biomass (life), which lives within various environments within the biosphere.
Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence. More than 2 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. 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. The total number of species is presently in rapid decline.
Evolution
Life, as we understand it, is currently only known to exist on the planet Earth. The
origin of life is still a poorly understood process, but it's thought to have occurred about 3.9 to 3.5 billion years ago during the
hadean or
archean eons on a primordial earth that had a substantially different environment than is found at present. These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of
evolution by
natural selection resulted in the formation of ever-more diverse life forms.
Species that were unable to adapt to the changing environment and competition from other life forms became extinct. However, the
fossil record retains evidence of many of these older species. Current fossil and
DNA evidence shows that all existing species can trace a continual ancestry back to the first primitive life forms. 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.
Microbes
The first form of life to develop on the Earth were microbes, and they remained the only form of life on the planet until about a billion years ago when multi-cellular organisms began to appear. Microorganisms are single-celled organisms that are generally smaller than the human eye can see. They include Bacteria, Fungi, Archaea and Protista.
These life forms are found in almost every location on the Earth where there's liquid water, including the interior of rocks within the planet.
Their reproduction is both rapid and profuse. The combination of a high mutation rate and a
horizontal gene transfer ability makes them highly adaptable, and able to survive in new environments, including
outer space. They form an essential part of the planetary ecosystem. However some microorganisms are
pathogenic and can post health risk to other organisms.
Plants and animals
The distinction between plant and animal life isn't sharply drawn, with some categories of life that stand between or across the two. Originally
Aristotle divided all living things between plants, which generally don't 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
fossil flora, remnants of plant life from a previous era. People in 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
terrain.
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" 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. This is an example of how human interaction with nature can blur the boundary of what is considered nature.
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 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,
archaea 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, a framework upon which cells can move about and be reorganized during development and maturation, and which supports the complex anatomy required for mobility.
Ecosystems
All forms of life interact 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, which can be defined as any situation where there's interaction between organisms and their environment.
Ecosystems are composed of a variety of
abiotic and
biotic components that function in an interrelated way. The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are: soil, atmosphere, radiation from the sun, water, and living organisms.
Each living organism has a continual relationship with every other element that makes up its environment. Within the ecosystem, species are connected and dependent upon one another in the
food chain, and exchange
energy and
matter between themselves as well as with their environment.
Every species has limits of tolerance to factors that affect its survival, reproductive success and ability to continue to thrive and interact sustainably with the rest of its environment, which in turn may have effects on these factors for many other species or even on the whole of life. The concept of an ecosystem is thus an important subject of study, as such study provides information needed to make decisions about how human life may interact in a way that allows the various ecosystems to be sustained for future use rather than used up or otherwise rendered ineffective. For the purpose of such study, 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.
The following ecosystems are examples of the kinds currently under intensive study:
Another classification can be made by reference to its communities, such as in the case of a
human ecosystem. Regional groupings of distinctive plant and animals best adapted to the region's physical
natural environment, latitude, altitude, and terrain are known as
biomes. 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; a theory studied as
earth system science (less formally known as
Gaia theory).
Human interrelationship
Although humans currently comprise only about one-half of one percent of the total living biomass on Earth, the human effect on nature is disproportionately large (thus generating the appearance of such terms as
man-nature continuum,
humanized nature or
human environment). Because of the extent of human influence, the boundaries between what we regard as nature and "made environments" isn't clear cut except at the extremes. Even at the extremes, the amount of natural environment that's free of discernible human influence is presently diminishing at an increasingly rapid pace, or, according to some, has already disappeared.
The development of technology by the human race has allowed the greater exploitation of natural resources and has helped to alleviate some of the risk from natural hazards. In spite of this progress, however, the fate of human
civilization remains closely linked to changes in the environment. There exists a highly complex feedback-loop between the use of advanced technology and changes to the environment that are only slowly becoming understood. Manmade threats to the Earth's natural environment include
pollution,
deforestation, and disasters such as oil spills. Humans have contributed to the
extinction of many plants and animals.
Humans employ nature for both leisure and economic activities. The acquisition of natural resources for industrial use remains the primary component of the world's economic system. Some activities, such as
hunting and
fishing, are used for both sustenance and leisure, often by different people.
Agriculture was first adopted around the
9th millennium BCE. Ranging from food production to
energy, nature influences economic wealth.
Although early humans gathered uncultivated plant materials for food and employed the medicinal properties of vegetation for healing, most modern human use of plants is through agriculture. The clearance of large tracts of land for crop growth has led to a significant reduction in the amount available of forestation and wetlands, resulting in the loss of habitat for many plant and animal species as well as increased erosion.
Wilderness
Wilderness is generally defined as a
natural environment on
Earth that hasn't 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 isn't 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). From this point of view, it's the wildness of a place that makes it a wilderness. The mere presence or activity of people doesn't 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.
Beauty in nature
Beauty in nature has long been a common theme in 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 that many philosophers agree about to explain what is seen as beautiful, the opinions are virtually endless.
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 began in
China during 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, the
Song Dynasty artist
Shi Erji listed "scenes lacking any places made inaccessible by nature," as one of the 12 things to avoid in painting.
In the
Western world the idea of wilderness having intrinsic value emerged in the 1800s, especially in the works of the
Romantic movement.
British artists
John Constable and
JMW Turner turned their attention to capturing the beauty of the natural world in their paintings. Before 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. This artistic movement also coincided with the
Transcendentalist movement in the Western world.
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 doesn't study nature because it's useful; he studies it because he delights in it, and he delights in it because it's beautiful.If nature were not beautiful, it wouldn't be worth knowing, and if nature were not worth knowing, life wouldn't be worth living. Of course I don't here speak of that beauty which strikes the senses, the beauty of qualities and of appearance; 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.
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
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's the study of nature.
Matter is commonly defined as the substance of which physical objects are composed. It constitutes the
observable universe. The visible components of the universe are now believed to compose only 4 percent of the total mass. The remainder is believed to consist of 23 percent cold
dark matter and 73 percent
dark energy. The exact nature of these components is still unknown and is currently under intensive investigation by physicists.
The behavior of matter and energy throughout the
observable universe appears to follow well-defined
physical laws. These laws have been employed to produce
cosmological models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty
physical constants that appear to be static across the observable universe. The values of these constants have been carefully measured, but the reason for their specific values remains a mystery.
Nature beyond Earth
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.
Outer space is certainly spacious, but it's far from empty. Outer space is sparsely filled with several dozen types of
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 spacecraft. Some of this
debris re-enters the atmosphere periodically.
Although the planet Earth is currently the only known body within the solar system to support life, current evidence suggests that in the distant past the planet
Mars possessed bodies of liquid water on the surface. For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen.
If life exists at all on Mars, it's most likely to be located underground where liquid water can still exist.
Conditions on the other terrestrial planets,
Mercury and
Venus, appears to be too harsh to support life as we know it. But it has been conjectured that
Europa, the fourth-largest moon of
Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.
Recently, the team of
Stéphane Udry have discovered a new planet named
Gliese 581 c, which is an
extrasolar planet orbiting the
red dwarf star Gliese 581. Gliese 581 c appears to lay in the
habitable zone of space surrounding the
star, and therefore could possibly host
life as we know it.
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