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77-408: Small means of insignificant size . Small may also refer to: Size In mathematical terms, "size is a concept abstracted from the process of measuring by comparing a longer to a shorter". Size is determined by the process of comparing or measuring objects, which results in the determination of the magnitude of a quantity, such as length or mass, relative to a unit of measurement . Such

154-409: A logarithmic scale . Such a scale is also used to measure the intensity of an earthquake , and this intensity is often referred to as the "size" of the event. In computing, file size is a measure of the size of a computer file , typically measured in bytes . The actual amount of disk space consumed by the file depends on the file system . The maximum file size a file system supports depends on

231-412: A nucleus of protons and neutrons , and a surrounding "cloud" of orbiting electrons which "take up space". However, this is only somewhat correct because subatomic particles and their properties are governed by their quantum nature , which means they do not act as everyday objects appear to act – they can act like waves as well as particles , and they do not have well-defined sizes or positions. In

308-491: A quantity of matter . As such, there is no single universally agreed scientific meaning of the word "matter". Scientifically, the term "mass" is well-defined, but "matter" can be defined in several ways. Sometimes in the field of physics "matter" is simply equated with particles that exhibit rest mass (i.e., that cannot travel at the speed of light), such as quarks and leptons. However, in both physics and chemistry , matter exhibits both wave -like and particle -like properties,

385-430: A baryon, is given a baryon number of 1/3. So the net amount of matter, as measured by the number of quarks (minus the number of antiquarks, which each have a baryon number of −1/3), which is proportional to baryon number, and number of leptons (minus antileptons), which is called the lepton number, is practically impossible to change in any process. Even in a nuclear bomb, none of the baryons (protons and neutrons of which

462-635: A charge of −1  e . They also carry colour charge , which is the equivalent of the electric charge for the strong interaction . Quarks also undergo radioactive decay , meaning that they are subject to the weak interaction . Baryons are strongly interacting fermions, and so are subject to Fermi–Dirac statistics. Amongst the baryons are the protons and neutrons, which occur in atomic nuclei, but many other unstable baryons exist as well. The term baryon usually refers to triquarks—particles made of three quarks. Also, "exotic" baryons made of four quarks and one antiquark are known as pentaquarks , but their existence

539-623: A desired degree, the resulting substance is said to be chemically pure . Chemical substances can exist in several different physical states or phases (e.g. solids , liquids , gases , or plasma ) without changing their chemical composition. Substances transition between these phases of matter in response to changes in temperature or pressure . Some chemical substances can be combined or converted into new substances by means of chemical reactions . Chemicals that do not possess this ability are said to be inert . A definition of "matter" based on its physical and chemical structure is: matter

616-441: A distance from other particles under everyday conditions; this creates the property of matter which appears to us as matter taking up space. For much of the history of the natural sciences , people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter , appeared in both ancient Greece and ancient India . Early philosophers who proposed

693-443: A few of its theoretical properties. There is considerable speculation both in science and science fiction as to why the observable universe is apparently almost entirely matter (in the sense of quarks and leptons but not antiquarks or antileptons), and whether other places are almost entirely antimatter (antiquarks and antileptons) instead. In the early universe, it is thought that matter and antimatter were equally represented, and

770-471: A magnitude is usually expressed as a numerical value of units on a previously established spatial scale , such as meters or inches . The sizes with which humans tend to be most familiar are body dimensions (measures of anthropometry ), which include measures such as human height and human body weight . These measures can, in the aggregate, allow the generation of commercially useful distributions of products that accommodate expected body sizes, as with

847-516: A sea of degenerate electrons. At a microscopic level, the constituent "particles" of matter such as protons, neutrons, and electrons obey the laws of quantum mechanics and exhibit wave–particle duality. At an even deeper level, protons and neutrons are made up of quarks and the force fields ( gluons ) that bind them together, leading to the next definition. As seen in the above discussion, many early definitions of what can be called "ordinary matter" were based upon its structure or "building blocks". On

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924-426: A subclass of matter. A common or traditional definition of matter is "anything that has mass and volume (occupies space )". For example, a car would be said to be made of matter, as it has mass and volume (occupies space). The observation that matter occupies space goes back to antiquity. However, an explanation for why matter occupies space is recent, and is argued to be a result of the phenomenon described in

1001-476: A temperature near absolute zero. The Pauli exclusion principle requires that only two fermions can occupy a quantum state, one spin-up and the other spin-down. Hence, at zero temperature, the fermions fill up sufficient levels to accommodate all the available fermions—and in the case of many fermions, the maximum kinetic energy (called the Fermi energy ) and the pressure of the gas becomes very large, and depends on

1078-405: Is approximately 12.5  MeV/ c , which is low compared to the mass of a nucleon (approximately 938  MeV/ c ). The bottom line is that most of the mass of everyday objects comes from the interaction energy of its elementary components. The Standard Model groups matter particles into three generations, where each generation consists of two quarks and two leptons. The first generation

1155-631: Is expected to be color superconducting . Strange matter is hypothesized to occur in the core of neutron stars , or, more speculatively, as isolated droplets that may vary in size from femtometers ( strangelets ) to kilometers ( quark stars ). In particle physics and astrophysics , the term is used in two ways, one broader and the other more specific. Leptons are particles of spin- 1 ⁄ 2 , meaning that they are fermions . They carry an electric charge of −1  e (charged leptons) or 0  e (neutrinos). Unlike quarks, leptons do not carry colour charge , meaning that they do not experience

1232-400: Is made up of atoms . Such atomic matter is also sometimes termed ordinary matter . As an example, deoxyribonucleic acid molecules (DNA) are matter under this definition because they are made of atoms. This definition can be extended to include charged atoms and molecules, so as to include plasmas (gases of ions) and electrolytes (ionic solutions), which are not obviously included in

1309-455: Is made up of neutron stars and white dwarfs. Strange matter is a particular form of quark matter , usually thought of as a liquid of up , down , and strange quarks. It is contrasted with nuclear matter , which is a liquid of neutrons and protons (which themselves are built out of up and down quarks), and with non-strange quark matter, which is a quark liquid that contains only up and down quarks. At high enough density, strange matter

1386-485: Is more subtle than it first appears. All the particles that make up ordinary matter (leptons and quarks) are elementary fermions, while all the force carriers are elementary bosons. The W and Z bosons that mediate the weak force are not made of quarks or leptons, and so are not ordinary matter, even if they have mass. In other words, mass is not something that is exclusive to ordinary matter. The quark–lepton definition of ordinary matter, however, identifies not only

1463-436: Is natural to phrase the definition as: "ordinary matter is anything that is made of the same things that atoms and molecules are made of". (However, notice that one also can make from these building blocks matter that is not atoms or molecules.) Then, because electrons are leptons, and protons and neutrons are made of quarks, this definition in turn leads to the definition of matter as being "quarks and leptons", which are two of

1540-429: Is no such thing as "anti-mass" or negative mass , so far as is known, although scientists do discuss the concept. Antimatter has the same (i.e. positive) mass property as its normal matter counterpart. Different fields of science use the term matter in different, and sometimes incompatible, ways. Some of these ways are based on loose historical meanings from a time when there was no reason to distinguish mass from simply

1617-480: Is not a substance but rather a quantitative property of matter and other substances or systems; various types of mass are defined within physics – including but not limited to rest mass , inertial mass , relativistic mass , mass–energy . While there are different views on what should be considered matter, the mass of a substance has exact scientific definitions. Another difference is that matter has an "opposite" called antimatter , but mass has no opposite—there

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1694-429: Is not generally accepted. Baryonic matter is the part of the universe that is made of baryons (including all atoms). This part of the universe does not include dark energy , dark matter , black holes or various forms of degenerate matter, such as those that compose white dwarf stars and neutron stars . Microwave light seen by Wilkinson Microwave Anisotropy Probe (WMAP) suggests that only about 4.6% of that part of

1771-403: Is the up and down quarks, the electron and the electron neutrino ; the second includes the charm and strange quarks, the muon and the muon neutrino ; the third generation consists of the top and bottom quarks and the tau and tau neutrino . The most natural explanation for this would be that quarks and leptons of higher generations are excited states of

1848-482: Is the unit of force, while kilogram is the unit of mass) on the surface of the Earth (its mass multiplied by the gravitational field strength ). Its weight will be less on Mars (where gravity is weaker), more on Saturn , and negligible in space when far from any significant source of gravity, but it will always have the same mass. Two objects of equal size, however, may have very different mass and weight, depending on

1925-477: The Pauli exclusion principle , which applies to fermions . Two particular examples where the exclusion principle clearly relates matter to the occupation of space are white dwarf stars and neutron stars, discussed further below. Thus, matter can be defined as everything composed of elementary fermions. Although we do not encounter them in everyday life, antiquarks (such as the antiproton ) and antileptons (such as

2002-499: The Standard Model of particle physics , matter is not a fundamental concept because the elementary constituents of atoms are quantum entities which do not have an inherent "size" or " volume " in any everyday sense of the word. Due to the exclusion principle and other fundamental interactions , some " point particles " known as fermions ( quarks , leptons ), and many composites and atoms, are effectively forced to keep

2079-427: The composition and density of the objects. By contrast, if two objects are known to have roughly the same composition, then some information about the size of one can be determined by measuring the size of the other, and determining the difference in weight between the two. For example, if two blocks of wood are equally dense, and it is known that one weighs ten kilograms and the other weighs twenty kilograms, and that

2156-421: The diameter of the observable universe about 91 billion light-years (28 × 10 ^  pc). In poetry , fiction , and other literature , size is occasionally assigned to characteristics that do not have measurable dimensions, such as the metaphorical reference to the size of a person's heart as a shorthand for describing their typical degree of kindness or generosity . With respect to physical size,

2233-570: The energy–momentum tensor that quantifies the amount of matter. This tensor gives the rest mass for the entire system. Matter, therefore, is sometimes considered as anything that contributes to the energy–momentum of a system, that is, anything that is not purely gravity. This view is commonly held in fields that deal with general relativity such as cosmology . In this view, light and other massless particles and fields are all part of matter. In particle physics, fermions are particles that obey Fermi–Dirac statistics . Fermions can be elementary, like

2310-645: The laws of nature . They coupled their ideas of soul, or lack thereof, into their theory of matter. The strongest developers and defenders of this theory were the Nyaya - Vaisheshika school, with the ideas of the Indian philosopher Kanada being the most followed. Buddhist philosophers also developed these ideas in late 1st-millennium CE, ideas that were similar to the Vaisheshika school, but ones that did not include any soul or conscience. Jain philosophers included

2387-556: The positron ) are the antiparticles of the quark and the lepton, are elementary fermions as well, and have essentially the same properties as quarks and leptons, including the applicability of the Pauli exclusion principle which can be said to prevent two particles from being in the same place at the same time (in the same state), i.e. makes each particle "take up space". This particular definition leads to matter being defined to include anything made of these antimatter particles as well as

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2464-570: The soul ( jiva ), adding qualities such as taste, smell, touch, and color to each atom. They extended the ideas found in early literature of the Hindus and Buddhists by adding that atoms are either humid or dry, and this quality cements matter. They also proposed the possibility that atoms combine because of the attraction of opposites, and the soul attaches to these atoms, transforms with karma residue, and transmigrates with each rebirth . In ancient Greece , pre-Socratic philosophers speculated

2541-508: The speed of light , the Planck constant , and the Newtonian constant of gravitation . In contrast, the largest observable thing is the observable universe . The comoving distance – the distance as would be measured at a specific time, including the present – between Earth and the edge of the observable universe is 46 billion light-years (14 × 10 ^  pc), making

2618-551: The strong interaction . Leptons also undergo radioactive decay, meaning that they are subject to the weak interaction . Leptons are massive particles, therefore are subject to gravity. In bulk , matter can exist in several different forms, or states of aggregation, known as phases , depending on ambient pressure , temperature and volume . A phase is a form of matter that has a relatively uniform chemical composition and physical properties (such as density , specific heat , refractive index , and so forth). These phases include

2695-410: The annihilation. In short, matter, as defined in physics, refers to baryons and leptons. The amount of matter is defined in terms of baryon and lepton number. Baryons and leptons can be created, but their creation is accompanied by antibaryons or antileptons; and they can be destroyed by annihilating them with antibaryons or antileptons. Since antibaryons/antileptons have negative baryon/lepton numbers,

2772-478: The antiparticle partners of one another. In October 2017, scientists reported further evidence that matter and antimatter , equally produced at the Big Bang , are identical, should completely annihilate each other and, as a result, the universe should not exist. This implies that there must be something, as yet unknown to scientists, that either stopped the complete mutual destruction of matter and antimatter in

2849-455: The atomic nuclei are composed) are destroyed—there are as many baryons after as before the reaction, so none of these matter particles are actually destroyed and none are even converted to non-matter particles (like photons of light or radiation). Instead, nuclear (and perhaps chromodynamic) binding energy is released, as these baryons become bound into mid-size nuclei having less energy (and, equivalently , less mass) per nucleon compared to

2926-650: The atoms definition. Alternatively, one can adopt the protons, neutrons, and electrons definition. A definition of "matter" more fine-scale than the atoms and molecules definition is: matter is made up of what atoms and molecules are made of , meaning anything made of positively charged protons , neutral neutrons , and negatively charged electrons . This definition goes beyond atoms and molecules, however, to include substances made from these building blocks that are not simply atoms or molecules, for example electron beams in an old cathode ray tube television, or white dwarf matter—typically, carbon and oxygen nuclei in

3003-439: The closer object. This also allows for the estimation of the size of large objects based on comparison of closer and farther parts of the same object. The perception of size can be distorted by manipulating these cues, for example through the creation of forced perspective . Some measures of size may also be determined by sound . Visually impaired humans often use echolocation to determine features of their surroundings, such as

3080-1309: The concept of resizing is occasionally presented in fairy tales , fantasy , and science fiction , placing humans in a different context within their natural environment by depicting them as having physically been made exceptionally large or exceptionally small through some fantastic means. Matter In classical physics and general chemistry , matter is any substance that has mass and takes up space by having volume . All everyday objects that can be touched are ultimately composed of atoms , which are made up of interacting subatomic particles , and in everyday as well as scientific usage, matter generally includes atoms and anything made up of them, and any particles (or combination of particles ) that act as if they have both rest mass and volume . However it does not include massless particles such as photons , or other energy phenomena or waves such as light or heat . Matter exists in various states (also known as phases ). These include classical everyday phases such as solid , liquid , and gas – for example water exists as ice , liquid water, and gaseous steam – but other states are possible, including plasma , Bose–Einstein condensates , fermionic condensates , and quark–gluon plasma . Usually atoms can be imagined as

3157-477: The creation of clothing sizes and shoe sizes , and with the standardization of door frame dimensions, ceiling heights, and bed sizes . The human experience of size can lead to a psychological tendency towards size bias, wherein the relative importance or perceived complexity of organisms and other objects is judged based on their size relative to humans , and particularly whether this size makes them easy to observe without aid. Humans most frequently perceive

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3234-414: The difference between the rest mass of the products of the annihilation and the rest mass of the original particle–antiparticle pair, which is often quite large. Depending on which definition of "matter" is adopted, antimatter can be said to be a particular subclass of matter, or the opposite of matter. Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities (as

3311-691: The disappearance of antimatter requires an asymmetry in physical laws called CP (charge–parity) symmetry violation , which can be obtained from the Standard Model, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics . Possible processes by which it came about are explored in more detail under baryogenesis . Formally, antimatter particles can be defined by their negative baryon number or lepton number , while "normal" (non-antimatter) matter particles have positive baryon or lepton number. These two classes of particles are

3388-399: The early forming universe, or that gave rise to an imbalance between the two forms. Two quantities that can define an amount of matter in the quark–lepton sense (and antimatter in an antiquark–antilepton sense), baryon number and lepton number , are conserved in the Standard Model. A baryon such as the proton or neutron has a baryon number of one, and a quark, because there are three in

3465-414: The early phase of the universe and still floating about. In cosmology , dark energy is the name given to the source of the repelling influence that is accelerating the rate of expansion of the universe . Its precise nature is currently a mystery, although its effects can reasonably be modeled by assigning matter-like properties such as energy density and pressure to the vacuum itself. Fully 70% of

3542-448: The early universe and the Big Bang theory require that this matter have energy and mass, but not be composed of ordinary baryons (protons and neutrons). The commonly accepted view is that most of the dark matter is non-baryonic in nature . As such, it is composed of particles as yet unobserved in the laboratory. Perhaps they are supersymmetric particles , which are not Standard Model particles but relics formed at very high energies in

3619-428: The electron—or composite, like the proton and neutron. In the Standard Model , there are two types of elementary fermions: quarks and leptons, which are discussed next. Quarks are massive particles of spin- 1 ⁄ 2 , implying that they are fermions . They carry an electric charge of − 1 ⁄ 3   e (down-type quarks) or + 2 ⁄ 3   e (up-type quarks). For comparison, an electron has

3696-438: The elementary building blocks of matter, but also includes composites made from the constituents (atoms and molecules, for example). Such composites contain an interaction energy that holds the constituents together, and may constitute the bulk of the mass of the composite. As an example, to a great extent, the mass of an atom is simply the sum of the masses of its constituent protons, neutrons and electrons. However, digging deeper,

3773-518: The field of thermodynamics . In nanomaterials, the vastly increased ratio of surface area to volume results in matter that can exhibit properties entirely different from those of bulk material, and not well described by any bulk phase (see nanomaterials for more details). Phases are sometimes called states of matter , but this term can lead to confusion with thermodynamic states . For example, two gases maintained at different pressures are in different thermodynamic states (different pressures), but in

3850-447: The first generations. If this turns out to be the case, it would imply that quarks and leptons are composite particles , rather than elementary particles . This quark–lepton definition of matter also leads to what can be described as "conservation of (net) matter" laws—discussed later below. Alternatively, one could return to the mass–volume–space concept of matter, leading to the next definition, in which antimatter becomes included as

3927-470: The four types of elementary fermions (the other two being antiquarks and antileptons, which can be considered antimatter as described later). Carithers and Grannis state: "Ordinary matter is composed entirely of first-generation particles, namely the [up] and [down] quarks, plus the electron and its neutrino." (Higher generations particles quickly decay into first-generation particles, and thus are not commonly encountered. ) This definition of ordinary matter

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4004-408: The fractions of energy in the universe contributed by different sources. Ordinary matter is divided into luminous matter (the stars and luminous gases and 0.005% radiation) and nonluminous matter (intergalactic gas and about 0.1% neutrinos and 0.04% supermassive black holes). Ordinary matter is uncommon. Modeled after Ostriker and Steinhardt. For more information, see NASA . Ordinary matter, in

4081-414: The mass–energy density of the universe. Hadronic matter can refer to 'ordinary' baryonic matter, made from hadrons (baryons and mesons ), or quark matter (a generalisation of atomic nuclei), i.e. the 'low' temperature QCD matter . It includes degenerate matter and the result of high energy heavy nuclei collisions. In physics, degenerate matter refers to the ground state of a gas of fermions at

4158-545: The matter density in the universe appears to be in the form of dark energy. Twenty-six percent is dark matter. Only 4% is ordinary matter. So less than 1 part in 20 is made out of matter we have observed experimentally or described in the standard model of particle physics. Of the other 96%, apart from the properties just mentioned, we know absolutely nothing. Exotic matter is a concept of particle physics , which may include dark matter and dark energy but goes further to include any hypothetical material that violates one or more of

4235-561: The naked eye may be measured when viewed through a microscope , while objects too large to fit within the field of vision may be measured using a telescope , or through extrapolation from known reference points. However, even very advanced measuring devices may still present a limited field of view . Objects being described by their relative size are often described as being comparatively big and little, or large and small, although "big and little tend to carry affective and evaluative connotations, whereas large and small tend to refer only to

4312-440: The number of bits reserved to store size information and the total size of the file system in terms of its capacity to store bits of information. In physics , the Planck length , denoted ℓ P , is a unit of length , equal to 1.616 199 (97) × 10   metres . It is a unit in the system of Planck units , developed by physicist Max Planck . The Planck length is defined in terms of three fundamental physical constants :

4389-412: The number of fermions rather than the temperature, unlike normal states of matter. Degenerate matter is thought to occur during the evolution of heavy stars. The demonstration by Subrahmanyan Chandrasekhar that white dwarf stars have a maximum allowed mass because of the exclusion principle caused a revolution in the theory of star evolution. Degenerate matter includes the part of the universe that

4466-414: The ordinary quark and lepton, and thus also anything made of mesons , which are unstable particles made up of a quark and an antiquark. In the context of relativity , mass is not an additive quantity, in the sense that one cannot add the rest masses of particles in a system to get the total rest mass of the system. In relativity, usually a more general view is that it is not the sum of rest masses , but

4543-401: The original small (hydrogen) and large (plutonium etc.) nuclei. Even in electron–positron annihilation , there is no net matter being destroyed, because there was zero net matter (zero total lepton number and baryon number) to begin with before the annihilation—one lepton minus one antilepton equals zero net lepton number—and this net amount matter does not change as it simply remains zero after

4620-447: The overall baryon/lepton numbers are not changed, so matter is conserved. However, baryons/leptons and antibaryons/antileptons all have positive mass, so the total amount of mass is not conserved. Further, outside of natural or artificial nuclear reactions, there is almost no antimatter generally available in the universe (see baryon asymmetry and leptogenesis ), so particle annihilation is rare in normal circumstances. Pie chart showing

4697-408: The particulate theory of matter include the ancient Indian philosopher Kanada (c. 6th–century BCE or after), pre-Socratic Greek philosopher Leucippus (~490 BCE), and pre-Socratic Greek philosopher Democritus (~470–380 BCE). Matter should not be confused with mass, as the two are not the same in modern physics. Matter is a general term describing any 'physical substance'. By contrast, mass

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4774-472: The properties of known forms of matter. Some such materials might possess hypothetical properties like negative mass . In ancient India , the Buddhist , Hindu , and Jain philosophical traditions each posited that matter was made of atoms ( paramanu , pudgala ) that were "eternal, indestructible, without parts, and innumerable" and which associated or dissociated to form more complex matter according to

4851-399: The protons and neutrons are made up of quarks bound together by gluon fields (see dynamics of quantum chromodynamics ) and these gluon fields contribute significantly to the mass of hadrons. In other words, most of what composes the "mass" of ordinary matter is due to the binding energy of quarks within protons and neutrons. For example, the sum of the mass of the three quarks in a nucleon

4928-503: The quarks and leptons definition, constitutes about 4% of the energy of the observable universe . The remaining energy is theorized to be due to exotic forms, of which 23% is dark matter and 73% is dark energy . In astrophysics and cosmology , dark matter is matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, but whose presence can be inferred from gravitational effects on visible matter. Observational evidence of

5005-408: The result of radioactive decay , lightning or cosmic rays ). This is because antimatter that came to exist on Earth outside the confines of a suitable physics laboratory would almost instantly meet the ordinary matter that Earth is made of, and be annihilated. Antiparticles and some stable antimatter (such as antihydrogen ) can be made in tiny amounts, but not in enough quantity to do more than test

5082-555: The same phase (both are gases). Antimatter is matter that is composed of the antiparticles of those that constitute ordinary matter. If a particle and its antiparticle come into contact with each other, the two annihilate ; that is, they may both be converted into other particles with equal energy in accordance with Albert Einstein 's equation E = mc . These new particles may be high-energy photons ( gamma rays ) or other particle–antiparticle pairs. The resulting particles are endowed with an amount of kinetic energy equal to

5159-405: The same kind. More formally, an object's magnitude is an ordering (or ranking) of the class of objects to which it belongs. There are various other mathematical concepts of size for sets, such as: In statistics ( hypothesis testing ), the "size" of the test refers to the rate of false positives , denoted by α. In astronomy , the magnitude of brightness or intensity of a star is measured on

5236-574: The scale of elementary particles, a definition that follows this tradition can be stated as: "ordinary matter is everything that is composed of quarks and leptons ", or "ordinary matter is everything that is composed of any elementary fermions except antiquarks and antileptons". The connection between these formulations follows. Leptons (the most famous being the electron ), and quarks (of which baryons , such as protons and neutrons , are made) combine to form atoms , which in turn form molecules . Because atoms and molecules are said to be matter, it

5313-454: The size of a thing". A wide range of other terms exist to describe things by their relative size, with small things being described for example as tiny, miniature, or minuscule, and large things being described as, for example, huge, gigantic, or enormous. Objects are also typically described as tall or short specifically relative to their vertical height, and as long or short specifically relative to their length along other directions. Although

5390-404: The size of an object may be reflected in its mass or its weight , each of these is a different concept. In scientific contexts, mass refers loosely to the amount of " matter " in an object (though "matter" may be difficult to define), whereas weight refers to the force experienced by an object due to gravity . An object with a mass of 1.0 kilogram will weigh approximately 9.81 newtons ( newton

5467-426: The size of objects through visual cues . One common means of perceiving size is to compare the size of a newly observed object with the size of a familiar object whose size is already known. Binocular vision gives humans the capacity for depth perception , which can be used to judge which of several objects is closer, and by how much, which allows for some estimation of the size of the more distant object relative to

5544-451: The size of spaces and objects. However, even humans who lack this ability can tell if a space that they are unable to see is large or small from hearing sounds echo in the space. Size can also be determined by touch , which is a process of haptic perception . The sizes of objects that can not readily be measured merely by sensory input may be evaluated with other kinds of measuring instruments . For example, objects too small to be seen with

5621-421: The so-called wave–particle duality . A chemical substance is a unique form of matter with constant chemical composition and characteristic properties . Chemical substances may take the form of a single element or chemical compounds . If two or more chemical substances can be combined without reacting , they may form a chemical mixture . If a mixture is separated to isolate one chemical substance to

5698-450: The ten kilogram block has a volume of one cubic foot, then it can be deduced that the twenty kilogram block has a volume of two cubic feet. The concept of size is often applied to ideas that have no physical reality. In mathematics , magnitude is the size of a mathematical object , which is an abstract object with no concrete existence. Magnitude is a property by which the object can be compared as larger or smaller than other objects of

5775-445: The three familiar ones ( solids , liquids , and gases ), as well as more exotic states of matter (such as plasmas , superfluids , supersolids , Bose–Einstein condensates , ...). A fluid may be a liquid, gas or plasma. There are also paramagnetic and ferromagnetic phases of magnetic materials . As conditions change, matter may change from one phase into another. These phenomena are called phase transitions and are studied in

5852-472: The underlying nature of the visible world. Thales (c. 624 BCE–c. 546 BCE) regarded water as the fundamental material of the world. Anaximander (c. 610 BCE–c. 546 BCE) posited that the basic material was wholly characterless or limitless: the Infinite ( apeiron ). Anaximenes (flourished 585 BCE, d. 528 BCE) posited that the basic stuff was pneuma or air. Heraclitus (c. 535 BCE–c. 475 BCE) seems to say

5929-411: The universe within range of the best telescopes (that is, matter that may be visible because light could reach us from it) is made of baryonic matter. About 26.8% is dark matter, and about 68.3% is dark energy. The great majority of ordinary matter in the universe is unseen, since visible stars and gas inside galaxies and clusters account for less than 10 per cent of the ordinary matter contribution to

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