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Hydrogen in its plasma state is the most abundant ordinary matter in the universe. Hydrogen discharge tube.jpg
Hydrogen in its plasma state is the most abundant ordinary matter in the universe.

In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. [1] 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. [1] :21 [2] 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. [3]


Usually atoms can be imagined as a nucleus of protons and neutrons, and a surrounding "cloud" of orbiting electrons which "take up space". [4] [5] 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 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 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. [6] Early philosophers who proposed the particulate theory of matter include the ancient Indian philosopher Kanada (c. 6th–century BCE or after), [7] pre-Socratic Greek philosopher Leucippus (~490 BCE), and pre-Socratic Greek philosopher Democritus (~470–380 BCE). [8]

Comparison with mass

Matter should not be confused with mass, as the two are not the same in modern physics. [9] Matter is a general term describing any 'physical substance'. By contrast, mass 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 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 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, the so-called wave–particle duality. [10] [11] [12]

Relation with chemical substance

Steam and liquid water are two different forms of the same pure chemical substance, water. Kochendes wasser02.jpg
Steam and liquid water are two different forms of the same pure chemical substance, water.

A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. [13] [14] 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. [15] If a mixture is separated to isolate one chemical substance to a desired degree, the resulting substance is said to be chemically pure. [16]

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.

Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a single oxygen atom (i.e. H2O). The atomic ratio of hydrogen to oxygen is always 2:1 in every molecule of water. Pure water will tend to boil near 100 °C (212 °F), an example of one of the characteristic properties that define it. Other notable chemical substances include diamond (a form of the element carbon), table salt (NaCl; an ionic compound), and refined sugar (C12H22O11; an organic compound).


Based on atoms

A definition of "matter" based on its physical and chemical structure is: matter is made up of atoms . [17] 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 the atoms definition. Alternatively, one can adopt the protons, neutrons, and electrons definition.

Based on protons, neutrons and electrons

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. [18] 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 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.

Based on quarks and leptons

Under the "quarks and leptons" definition, the elementary and composite particles made of the quarks (in purple) and leptons (in green) would be matter--while the gauge bosons (in red) would not be matter. However, interaction energy inherent to composite particles (for example, gluons involved in neutrons and protons) contribute to the mass of ordinary matter. Standard Model of Elementary Particles.svg
Under the "quarks and leptons" definition, the elementary and composite particles made of the quarks (in purple) and leptons (in green) would be matter—while the gauge bosons (in red) would not be matter. However, interaction energy inherent to composite particles (for example, gluons involved in neutrons and protons) contribute to the mass of ordinary matter.

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 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". [19] [20] [21] 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 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 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." [20] (Higher generations particles quickly decay into first-generation particles, and thus are not commonly encountered. [22] )

This definition of ordinary matter 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. [23] 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. [24] In other words, mass is not something that is exclusive to ordinary matter.

The quark–lepton definition of ordinary matter, however, identifies not only 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, the protons and neutrons are made up of quarks bound together by gluon fields (see dynamics of quantum chromodynamics) and these gluons fields contribute significantly to the mass of hadrons. [25] In other words, most of what composes the "mass" of ordinary matter is due to the binding energy of quarks within protons and neutrons. [26] For example, the sum of the mass of the three quarks in a nucleon is approximately 12.5  MeV/c2 , which is low compared to the mass of a nucleon (approximately 938  MeV/c2 ). [27] [28] 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 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 . [29] The most natural explanation for this would be that quarks and leptons of higher generations are excited states of 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. [30]

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 a subclass of matter.

Based on elementary fermions (mass, volume, and space)

A common or traditional definition of matter is "anything that has mass and volume (occupies space)". [31] [32] 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 the Pauli exclusion principle, [33] [34] 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 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 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 general relativity and cosmology

In the context of relativity, mass is not an additive quantity, in the sense that one can not add the rest masses of particles in a system to get the total rest mass of the system. [1] :21 Thus, in relativity usually a more general view is that it is not the sum of rest masses, but 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. [35] [36] 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 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-12, implying that they are fermions. They carry an electric charge of −13  e (down-type quarks) or +23 e (up-type quarks). For comparison, an electron has 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.

Quark properties [37]
namesymbolspinelectric charge
(MeV/ c 2)
mass comparable toantiparticleantiparticle
up-type quarks
12+231.5 to 3.3~ 5 electronsantiup
12+231160 to 1340~1 protonanticharm
12+23169,100 to 173,300~180 protons or
~1 tungsten atom
down-type quarks
12133.5 to 6.0~10 electronsantidown
121370 to 130~ 200 electronsantistrange
12134130 to 4370~ 5 protonsantibottom


Quark structure of a proton: 2 up quarks and 1 down quark. Quark structure proton.svg
Quark structure of a proton: 2 up quarks and 1 down quark.

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 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 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 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. [38]

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 the mass–energy density of the universe. [39]


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. [40] It includes degenerate matter and the result of high energy heavy nuclei collisions. [41]


In physics, degenerate matter refers to the ground state of a gas of fermions at a temperature near absolute zero. [42] 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 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. [43] 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. [44]

Degenerate matter includes the part of the universe that 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 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).

Two meanings

In particle physics and astrophysics, the term is used in two ways, one broader and the other more specific.

  1. The broader meaning is just quark matter that contains three flavors of quarks: up, down, and strange. In this definition, there is a critical pressure and an associated critical density, and when nuclear matter (made of protons and neutrons) is compressed beyond this density, the protons and neutrons dissociate into quarks, yielding quark matter (probably strange matter).
  2. The narrower meaning is quark matter that is more stable than nuclear matter. The idea that this could happen is the "strange matter hypothesis" of Bodmer [45] and Witten. [46] In this definition, the critical pressure is zero: the true ground state of matter is always quark matter. The nuclei that we see in the matter around us, which are droplets of nuclear matter, are actually metastable, and given enough time (or the right external stimulus) would decay into droplets of strange matter, i.e. strangelets.


Leptons are particles of spin-12, 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 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.

Lepton properties
namesymbolspinelectric charge
(MeV/ c 2)
mass comparable toantiparticleantiparticle
charged leptons [47]
12−10.51101 electron antielectron
12−1105.7~ 200 electronsantimuon
12−11,777~ 2 protonsantitau
neutrinos [48]
electron neutrino
120< 0.000460< 11000 electronelectron antineutrino
muon neutrino
120< 0.19< 12 electronmuon antineutrino
tau neutrino
120< 18.2< 40 electronstau antineutrino


Phase diagram for a typical substance at a fixed volume Phase diagram for pure substance.JPG
Phase diagram for a typical substance at a fixed volume

In bulk, matter can exist in several different forms, or states of aggregation, known as phases , [49] depending on ambient pressure, temperature and volume. [50] 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 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 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 the same phase (both are gases).


Unsolved problem in physics:

Baryon asymmetry. Why is there far more matter than antimatter in the observable universe?

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 = mc2 . 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 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 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 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 the disappearance of antimatter requires an asymmetry in physical laws called CP (charge–parity) symmetry violation, which can be obtained from the Standard Model, [51] 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. [52] These two classes of particles are 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. [53] This implies that there must be something, as yet unknown to scientists, that either stopped the complete mutual destruction of matter and antimatter in 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 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 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 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 the annihilation. [54]

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, 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 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. [55] For more information, see NASA.

  Dark energy (73%)
  Dark matter (23%)
  Non-luminous matter (3.6%)
  Luminous matter (0.4%)

Ordinary matter, in 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 [56] [57] and 73% is dark energy. [58] [59]

Galaxy rotation curve for the Milky Way. Vertical axis is speed of rotation about the galactic center. Horizontal axis is distance from the galactic center. The sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red. The difference is due to dark matter or perhaps a modification of the law of gravity. Scatter in observations is indicated roughly by gray bars. Rotation curve (Milky Way).svg
Galaxy rotation curve for the Milky Way. Vertical axis is speed of rotation about the galactic center. Horizontal axis is distance from the galactic center. The sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red. The difference is due to dark matter or perhaps a modification of the law of gravity. Scatter in observations is indicated roughly by gray bars.

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. [63] [64] Observational evidence of 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. [63] As such, it is composed of particles as yet unobserved in the laboratory. Perhaps they are supersymmetric particles, [65] which are not Standard Model particles but relics formed at very high energies in the early phase of the universe and still floating about. [63]


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. [66] [67]

Fully 70% of 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.

Lee Smolin (2007), The Trouble with Physics, p. 16


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 the properties of known forms of matter. Some such materials might possess hypothetical properties like negative mass.

Historical and philosophical study

Classical antiquity (c. 600 BCE–c. 322 BCE)

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 the laws of nature. [6] 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. [6] [7] Buddhist philosophers also developed these ideas in late 1st-millennium CE, ideas that were similar to the Vaisheshika school, but one that did not include any soul or conscience. [6] Jain philosophers included the soul (jiva), adding qualities such as taste, smell, touch, and color to each atom. [68] 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. [6]

In ancient Greece, pre-Socratic philosophers speculated 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–c. 475 BCE) seems to say the basic element is fire, though perhaps he means that all is change. Empedocles (c. 490–430 BCE) spoke of four elements of which everything was made: earth, water, air, and fire. [69] Meanwhile, Parmenides argued that change does not exist, and Democritus argued that everything is composed of minuscule, inert bodies of all shapes called atoms, a philosophy called atomism. All of these notions had deep philosophical problems. [70]

Aristotle (384–322 BCE) was the first to put the conception on a sound philosophical basis, which he did in his natural philosophy, especially in Physics book I. [71] He adopted as reasonable suppositions the four Empedoclean elements, but added a fifth, aether. Nevertheless, these elements are not basic in Aristotle's mind. Rather they, like everything else in the visible world, are composed of the basic principles matter and form.

For my definition of matter is just this—the primary substratum of each thing, from which it comes to be without qualification, and which persists in the result.

Aristotle, Physics I:9:192a32

The word Aristotle uses for matter, ὕλη (hyle or hule), can be literally translated as wood or timber, that is, "raw material" for building. [72] Indeed, Aristotle's conception of matter is intrinsically linked to something being made or composed. In other words, in contrast to the early modern conception of matter as simply occupying space, matter for Aristotle is definitionally linked to process or change: matter is what underlies a change of substance. For example, a horse eats grass: the horse changes the grass into itself; the grass as such does not persist in the horse, but some aspect of it—its matter—does. The matter is not specifically described (e.g., as atoms), but consists of whatever persists in the change of substance from grass to horse. Matter in this understanding does not exist independently (i.e., as a substance), but exists interdependently (i.e., as a "principle") with form and only insofar as it underlies change. It can be helpful to conceive of the relationship of matter and form as very similar to that between parts and whole. For Aristotle, matter as such can only receive actuality from form; it has no activity or actuality in itself, similar to the way that parts as such only have their existence in a whole (otherwise they would be independent wholes).

Age of Enlightenment

French philosopher René Descartes (1596–1650) originated the modern conception of matter. He was primarily a geometer. Instead of, like Aristotle, deducing the existence of matter from the physical reality of change, Descartes arbitrarily postulated matter to be an abstract, mathematical substance that occupies space:

So, extension in length, breadth, and depth, constitutes the nature of bodily substance; and thought constitutes the nature of thinking substance. And everything else attributable to body presupposes extension, and is only a mode of an extended thing.

René Descartes, Principles of Philosophy [73]

For Descartes, matter has only the property of extension, so its only activity aside from locomotion is to exclude other bodies: [74] this is the mechanical philosophy. Descartes makes an absolute distinction between mind, which he defines as unextended, thinking substance, and matter, which he defines as unthinking, extended substance. [75] They are independent things. In contrast, Aristotle defines matter and the formal/forming principle as complementary principles that together compose one independent thing (substance). In short, Aristotle defines matter (roughly speaking) as what things are actually made of (with a potential independent existence), but Descartes elevates matter to an actual independent thing in itself.

The continuity and difference between Descartes's and Aristotle's conceptions is noteworthy. In both conceptions, matter is passive or inert. In the respective conceptions matter has different relationships to intelligence. For Aristotle, matter and intelligence (form) exist together in an interdependent relationship, whereas for Descartes, matter and intelligence (mind) are definitionally opposed, independent substances. [76]

Descartes's justification for restricting the inherent qualities of matter to extension is its permanence, but his real criterion is not permanence (which equally applied to color and resistance), but his desire to use geometry to explain all material properties. [77] Like Descartes, Hobbes, Boyle, and Locke argued that the inherent properties of bodies were limited to extension, and that so-called secondary qualities, like color, were only products of human perception. [78]

English philosopher Isaac Newton (1643–1727) inherited Descartes's mechanical conception of matter. In the third of his "Rules of Reasoning in Philosophy", Newton lists the universal qualities of matter as "extension, hardness, impenetrability, mobility, and inertia". [79] Similarly in Optics he conjectures that God created matter as "solid, massy, hard, impenetrable, movable particles", which were "...even so very hard as never to wear or break in pieces". [80] The "primary" properties of matter were amenable to mathematical description, unlike "secondary" qualities such as color or taste. Like Descartes, Newton rejected the essential nature of secondary qualities. [81]

Newton developed Descartes's notion of matter by restoring to matter intrinsic properties in addition to extension (at least on a limited basis), such as mass. Newton's use of gravitational force, which worked "at a distance", effectively repudiated Descartes's mechanics, in which interactions happened exclusively by contact. [82]

Though Newton's gravity would seem to be a power of bodies, Newton himself did not admit it to be an essential property of matter. Carrying the logic forward more consistently, Joseph Priestley (1733–1804) argued that corporeal properties transcend contact mechanics: chemical properties require the capacity for attraction. [82] He argued matter has other inherent powers besides the so-called primary qualities of Descartes, et al. [83]

19th and 20th centuries

Since Priestley's time, there has been a massive expansion in knowledge of the constituents of the material world (viz., molecules, atoms, subatomic particles). In the 19th century, following the development of the periodic table, and of atomic theory, atoms were seen as being the fundamental constituents of matter; atoms formed molecules and compounds. [84]

The common definition in terms of occupying space and having mass is in contrast with most physical and chemical definitions of matter, which rely instead upon its structure and upon attributes not necessarily related to volume and mass. At the turn of the nineteenth century, the knowledge of matter began a rapid evolution.

Aspects of the Newtonian view still held sway. James Clerk Maxwell discussed matter in his work Matter and Motion. [85] He carefully separates "matter" from space and time, and defines it in terms of the object referred to in Newton's first law of motion.

However, the Newtonian picture was not the whole story. In the 19th century, the term "matter" was actively discussed by a host of scientists and philosophers, and a brief outline can be found in Levere. [86] [ further explanation needed ] A textbook discussion from 1870 suggests matter is what is made up of atoms: [87]

Three divisions of matter are recognized in science: masses, molecules and atoms.
A Mass of matter is any portion of matter appreciable by the senses.
A Molecule is the smallest particle of matter into which a body can be divided without losing its identity.
An Atom is a still smaller particle produced by division of a molecule.

Rather than simply having the attributes of mass and occupying space, matter was held to have chemical and electrical properties. In 1909 the famous physicist J. J. Thomson (1856–1940) wrote about the "constitution of matter" and was concerned with the possible connection between matter and electrical charge. [88]

In the late 19th century with the discovery of the electron, and in the early 20th century, with the Geiger–Marsden experiment discovery of the atomic nucleus, and the birth of particle physics, matter was seen as made up of electrons, protons and neutrons interacting to form atoms. There then developed an entire literature concerning the "structure of matter", ranging from the "electrical structure" in the early 20th century, [89] to the more recent "quark structure of matter", introduced as early as 1992 by Jacob with the remark: "Understanding the quark structure of matter has been one of the most important advances in contemporary physics." [90] [ further explanation needed ] In this connection, physicists speak of matter fields, and speak of particles as "quantum excitations of a mode of the matter field". [10] [11] And here is a quote from de Sabbata and Gasperini: "With the word "matter" we denote, in this context, the sources of the interactions, that is spinor fields (like quarks and leptons), which are believed to be the fundamental components of matter, or scalar fields, like the Higgs particles, which are used to introduced mass in a gauge theory (and that, however, could be composed of more fundamental fermion fields)." [91] [ further explanation needed ]

Protons and neutrons however are not indivisible: they can be divided into quarks. And electrons are part of a particle family called leptons. Both quarks and leptons are elementary particles, and were in 2004 seen by authors of an undergraduate text as being the fundamental constituents of matter. [92]

These quarks and leptons interact through four fundamental forces: gravity, electromagnetism, weak interactions, and strong interactions. The Standard Model of particle physics is currently the best explanation for all of physics, but despite decades of efforts, gravity cannot yet be accounted for at the quantum level; it is only described by classical physics (see quantum gravity and graviton) [93] to the frustration of theoreticians like Stephen Hawking. Interactions between quarks and leptons are the result of an exchange of force-carrying particles such as photons between quarks and leptons. [94] The force-carrying particles are not themselves building blocks. As one consequence, mass and energy (which to our present knowledge cannot be created or destroyed) cannot always be related to matter (which can be created out of non-matter particles such as photons, or even out of pure energy, such as kinetic energy).[ citation needed ] Force mediators are usually not considered matter: the mediators of the electric force (photons) possess energy (see Planck relation) and the mediators of the weak force (W and Z bosons) have mass, but neither are considered matter either. [95] However, while these quanta are not considered matter, they do contribute to the total mass of atoms, subatomic particles, and all systems that contain them. [96] [97]


The modern conception of matter has been refined many times in history, in light of the improvement in knowledge of just what the basic building blocks are, and in how they interact. The term "matter" is used throughout physics in a wide variety of contexts: for example, one refers to "condensed matter physics", [98] "elementary matter", [99] "partonic" matter, "dark" matter, "anti"-matter, "strange" matter, and "nuclear" matter. In discussions of matter and antimatter, the former has been referred to by Alfvén as koinomatter (Gk. common matter). [100] It is fair to say that in physics, there is no broad consensus as to a general definition of matter, and the term "matter" usually is used in conjunction with a specifying modifier.

The history of the concept of matter is a history of the fundamental length scales used to define matter. Different building blocks apply depending upon whether one defines matter on an atomic or elementary particle level. One may use a definition that matter is atoms, or that matter is hadrons, or that matter is leptons and quarks depending upon the scale at which one wishes to define matter. [101]

These quarks and leptons interact through four fundamental forces: gravity, electromagnetism, weak interactions, and strong interactions. The Standard Model of particle physics is currently the best explanation for all of physics, but despite decades of efforts, gravity cannot yet be accounted for at the quantum level; it is only described by classical physics (see quantum gravity and graviton). [93]

See also

Related Research Articles

<span class="mw-page-title-main">Atom</span> Smallest unit of a chemical element

Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element.

<span class="mw-page-title-main">Elementary particle</span> Subatomic particle having no known substructure

In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. The Standard Model presently recognizes seventeen distinct particles—twelve fermions and five bosons. As a consequence of flavor and color combinations and antimatter, the fermions and bosons are known to have 48 and 13 variations, respectively. Among the 61 elementary particles embraced by the Standard Model number: electrons and other leptons, quarks, and the fundamental bosons. Subatomic particles such as protons or neutrons, which contain two or more elementary particles, are known as composite particles.

<span class="mw-page-title-main">Fermion</span> Type of subatomic particle

In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Fermions have a half-odd-integer spin and obey the Pauli exclusion principle. These particles include all quarks and leptons and all composite particles made of an odd number of these, such as all baryons and many atoms and nuclei. Fermions differ from bosons, which obey Bose–Einstein statistics.

<span class="mw-page-title-main">Hadron</span> Composite subatomic particle

In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules, which are held together by the electric force. Most of the mass of ordinary matter comes from two hadrons: the proton and the neutron, while most of the mass of the protons and neutrons is in turn due to the binding energy of their constituent quarks, due to the strong force.

<span class="mw-page-title-main">Particle physics</span> Study of subatomic particles and forces

Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combination of protons and neutrons is called nuclear physics.

<span class="mw-page-title-main">Proton decay</span> Hypothetical particle decay process of a proton

In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothesis was first formulated by Andrei Sakharov in 1967. Despite significant experimental effort, proton decay has never been observed. If it does decay via a positron, the proton's half-life is constrained to be at least 1.67×1034 years.

<span class="mw-page-title-main">Quark</span> Elementary particle, main constituent of matter

A quark is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly observable matter is composed of up quarks, down quarks and electrons. Owing to a phenomenon known as color confinement, quarks are never found in isolation; they can be found only within hadrons, which include baryons and mesons, or in quark–gluon plasmas. For this reason, much of what is known about quarks has been drawn from observations of hadrons.

<span class="mw-page-title-main">Standard Model</span> Theory of forces and subatomic particles

The Standard Model of particle physics is the theory describing three of the four known fundamental forces in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.

Degenerate matter occurs when the Pauli exclusion principle significantly alters a state of matter at low temperature. The term is used in astrophysics to refer to dense stellar objects such as white dwarfs and neutron stars, where thermal pressure alone is not enough to avoid gravitational collapse. The term also applies to metals in the Fermi gas approximation.

<span class="mw-page-title-main">Subatomic particle</span> Particle smaller than an atom

In physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles, or an elementary particle, which is not composed of other particles. Particle physics and nuclear physics study these particles and how they interact. Most force carrying particles like photons or gluons are called bosons and, although they have discrete quanta of energy, do not have rest mass or discrete diameters and are unlike the former particles that have rest mass and cannot overlap or combine which are called fermions. The W and Z bosons, however, are an exception to this rule and have relatively large rest masses at approximately 80GeV and 90GeV respectively.

<span class="mw-page-title-main">W and Z bosons</span> Elementary particles; gauge bosons that mediate the weak interaction

In particle physics, the W and Z bosons are vector bosons that are together known as the weak bosons or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are
, and
. The
 bosons have either a positive or negative electric charge of 1 elementary charge and are each other's antiparticles. The
 boson is electrically neutral and is its own antiparticle. The three particles each have a spin of 1. The
 bosons have a magnetic moment, but the
has none. All three of these particles are very short-lived, with a half-life of about 3×10−25 s. Their experimental discovery was pivotal in establishing what is now called the Standard Model of particle physics.

<span class="mw-page-title-main">Baryogenesis</span> Hypothesized early universe process

In physical cosmology, baryogenesis is the physical process that is hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e. the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe.

In particle physics, preons are hypothetical point particles, conceived of as sub-components of quarks and leptons. The word was coined by Jogesh Pati and Abdus Salam, in 1974. Interest in preon models peaked in the 1980s but has slowed, as the Standard Model of particle physics continues to describe physics mostly successfully, and no direct experimental evidence for lepton and quark compositeness has been found. Preons come in four varieties: plus, anti-plus, zero, and anti-zero. W bosons have six preons, and quarks and leptons have only three.

In particle physics, flavour or flavor refers to the species of an elementary particle. The Standard Model counts six flavours of quarks and six flavours of leptons. They are conventionally parameterized with flavour quantum numbers that are assigned to all subatomic particles. They can also be described by some of the family symmetries proposed for the quark-lepton generations.

Even restricting the discussion to physics, scientists do not have a unique definition of what matter is. In the currently known particle physics, summarised by the standard model of elementary particles and interactions, it is possible to distinguish in an absolute sense particles of matter and particles of antimatter. This is particularly easy for those particles that carry electric charge, such as electrons, protons or quarks, while the distinction is more subtle in the case of neutrinos, fundamental elementary particles that do not carry electric charge. In the standard model, it is not possible to create a net amount of matter particles—or more precisely, it is not possible to change the net number of leptons or of quarks in any perturbative reaction among particles. This remark is consistent with all existing observations.

Leptoquarks are hypothetical particles that would interact with quarks and leptons. Leptoquarks are color-triplet bosons that carry both lepton and baryon numbers. Their other quantum numbers, like spin, (fractional) electric charge and weak isospin vary among models. Leptoquarks are encountered in various extensions of the Standard Model, such as technicolor theories, theories of quark–lepton unification (e.g., Pati–Salam model), or GUTs based on SU(5), SO(10), E6, etc. Leptoquarks are currently searched for in experiments ATLAS and CMS at the Large Hadron Collider in CERN.

<span class="mw-page-title-main">Boson</span> Type of subatomic particle

In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value. Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have odd half-integer spin. Every observed subatomic particle is either a boson or a fermion. Paul Dirac coined the name boson to commemorate the contribution of Satyendra Nath Bose, an Indian physicist.

This glossary of physics is a list of definitions of terms and concepts relevant to physics, its sub-disciplines, and related fields, including mechanics, materials science, nuclear physics, particle physics, and thermodynamics. For more inclusive glossaries concerning related fields of science and technology, see Glossary of chemistry terms, Glossary of astronomy, Glossary of areas of mathematics, and Glossary of engineering.

<span class="mw-page-title-main">History of subatomic physics</span> Chronological listing of experiments and discoveries

The idea that matter consists of smaller particles and that there exists a limited number of sorts of primary, smallest particles in nature has existed in natural philosophy at least since the 6th century BC. Such ideas gained physical credibility beginning in the 19th century, but the concept of "elementary particle" underwent some changes in its meaning: notably, modern physics no longer deems elementary particles indestructible. Even elementary particles can decay or collide destructively; they can cease to exist and create (other) particles in result.


  1. 1 2 3 R. Penrose (1991). "The mass of the classical vacuum". In S. Saunders; H.R. Brown (eds.). The Philosophy of Vacuum. Oxford University Press. pp. 21–26. ISBN   978-0-19-824449-3.
  2. "Matter (physics)". McGraw-Hill's Access Science: Encyclopedia of Science and Technology Online. Archived from the original on 17 June 2011. Retrieved 24 May 2009.
  3. "RHIC Scientists Serve Up "Perfect" Liquid" (Press release). Brookhaven National Laboratory. 18 April 2005. Retrieved 15 September 2009.
  4. P. Davies (1992). The New Physics: A Synthesis. Cambridge University Press. p. 1. ISBN   978-0-521-43831-5.
  5. Gerard't Hooft (1997). In search of the ultimate building blocks . Cambridge University Press. p.  6. ISBN   978-0-521-57883-7.
  6. 1 2 3 4 5 Bernard Pullman (2001). The Atom in the History of Human Thought. Oxford University Press. pp. 77–84. ISBN   978-0-19-515040-7.
  7. 1 2 Jeaneane D. Fowler (2002). Perspectives of reality: an introduction to the philosophy of Hinduism. Sussex Academic Press. pp. 99–115. ISBN   978-1-898723-93-6.
  8. J. Olmsted; G.M. Williams (1996). Chemistry: The Molecular Science (2nd ed.). Jones & Bartlett. p. 40. ISBN   978-0-8151-8450-8.
  9. J. Mongillo (2007). Nanotechnology 101. Greenwood Publishing. p. 30. ISBN   978-0-313-33880-9.
  10. 1 2 P.C.W. Davies (1979). The Forces of Nature . Cambridge University Press. p.  116. ISBN   978-0-521-22523-6. matter field.
  11. 1 2 S. Weinberg (1998). The Quantum Theory of Fields. Cambridge University Press. p. 2. ISBN   978-0-521-55002-4.
  12. M. Masujima (2008). Path Integral Quantization and Stochastic Quantization. Springer. p. 103. ISBN   978-3-540-87850-6.
  13. Hale, Bob (19 September 2013). Necessary Beings: An Essay on Ontology, Modality, and the Relations Between Them. OUP Oxford. ISBN   9780191648342. Archived from the original on 13 January 2018.
  14. IUPAC, Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006) "Chemical Substance". doi:10.1351/goldbook.C01039
  15. "2.1: Pure Substances and Mixtures". Chemistry LibreTexts. 15 March 2017. Retrieved 7 January 2024.
  16. Hunter, Lawrence E. (13 January 2012). The Processes of Life: An Introduction to Molecular Biology. MIT Press. ISBN   9780262299947. Archived from the original on 13 January 2018.
  17. G.F. Barker (1870). "Divisions of matter". A text-book of elementary chemistry: theoretical and inorganic. John F Morton & Co. p. 2. ISBN   978-1-4460-2206-1.
  18. M. de Podesta (2002). Understanding the Properties of Matter (2nd ed.). CRC Press. p. 8. ISBN   978-0-415-25788-6.
  19. B. Povh; K. Rith; C. Scholz; F. Zetsche; M. Lavelle (2004). "Part I: Analysis: The building blocks of matter". Particles and Nuclei: An Introduction to the Physical Concepts (4th ed.). Springer. ISBN   978-3-540-20168-7. Ordinary matter is composed entirely of first-generation particles, namely the u and d quarks, plus the electron and its neutrino.
  20. 1 2 B. Carithers; P. Grannis (1995). "Discovery of the Top Quark" (PDF). Beam Line . 25 (3): 4–16.
  21. Tsan, Ung Chan (2006). "What Is a Matter Particle?" (PDF). International Journal of Modern Physics E. 15 (1): 259–272. Bibcode:2006IJMPE..15..259C. doi:10.1142/S0218301306003916. S2CID   121628541. (From Abstract:) Positive baryon numbers (A>0) and positive lepton numbers (L>0) characterize matter particles while negative baryon numbers and negative lepton numbers characterize antimatter particles. Matter particles and antimatter particles belong to two distinct classes of particles. Matter neutral particles are particles characterized by both zero baryon number and zero lepton number. This third class of particles includes mesons formed by a quark and an antiquark pair (a pair of matter particle and antimatter particle) and bosons which are messengers of known interactions (photons for electromagnetism, W and Z bosons for the weak interaction, gluons for the strong interaction). The antiparticle of a matter particle belongs to the class of antimatter particles, the antiparticle of an antimatter particle belongs to the class of matter particles.
  22. D. Green (2005). High PT physics at hadron colliders. Cambridge University Press. p. 23. ISBN   978-0-521-83509-1.
  23. L. Smolin (2007). The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next. Mariner Books. p. 67. ISBN   978-0-618-91868-3.
  24. The W boson mass is 80.398 GeV; see Figure 1 in C. Amsler; et al. (Particle Data Group) (2008). "Review of Particle Physics: The Mass and Width of the W Boson" (PDF). Physics Letters B . 667 (1): 1. Bibcode:2008PhLB..667....1A. doi:10.1016/j.physletb.2008.07.018. hdl: 1854/LU-685594 .
  25. I.J.R. Aitchison; A.J.G. Hey (2004). Gauge Theories in Particle Physics. CRC Press. p. 48. ISBN   978-0-7503-0864-9.
  26. B. Povh; K. Rith; C. Scholz; F. Zetsche; M. Lavelle (2004). Particles and Nuclei: An Introduction to the Physical Concepts. Springer. p. 103. ISBN   978-3-540-20168-7.
  27. A.M. Green (2004). Hadronic Physics from Lattice QCD. World Scientific. p. 120. ISBN   978-981-256-022-3.
  28. T. Hatsuda (2008). "Quark–gluon plasma and QCD". In H. Akai (ed.). Condensed matter theories. Vol. 21. Nova Publishers. p. 296. ISBN   978-1-60021-501-8.
  29. K.W. Staley (2004). "Origins of the Third Generation of Matter". The Evidence for the Top Quark. Cambridge University Press. p. 8. ISBN   978-0-521-82710-2.
  30. Y. Ne'eman; Y. Kirsh (1996). The Particle Hunters (2nd ed.). Cambridge University Press. p. 276. ISBN   978-0-521-47686-7. [T]he most natural explanation to the existence of higher generations of quarks and leptons is that they correspond to excited states of the first generation, and experience suggests that excited systems must be composite
  31. S.M. Walker; A. King (2005). What is Matter?. Lerner Publications. p. 7. ISBN   978-0-8225-5131-7.
  32. J.Kenkel; P.B. Kelter; D.S. Hage (2000). Chemistry: An Industry-based Introduction with CD-ROM. CRC Press. p. 2. ISBN   978-1-56670-303-1. All basic science textbooks define matter as simply the collective aggregate of all material substances that occupy space and have mass or weight.
  33. K.A. Peacock (2008). The Quantum Revolution: A Historical Perspective. Greenwood Publishing Group. p. 47. ISBN   978-0-313-33448-1.
  34. M.H. Krieger (1998). Constitutions of Matter: Mathematically Modeling the Most Everyday of Physical Phenomena. University of Chicago Press. p. 22. ISBN   978-0-226-45305-7.
  35. S.M. Caroll (2004). Spacetime and Geometry. Addison Wesley. pp. 163–164. ISBN   978-0-8053-8732-2.
  36. P. Davies (1992). The New Physics: A Synthesis. Cambridge University Press. p. 499. ISBN   978-0-521-43831-5. Matter fields: the fields whose quanta describe the elementary particles that make up the material content of the Universe (as opposed to the gravitons and their supersymmetric partners).
  37. C. Amsler; et al. (Particle Data Group) (2008). "Reviews of Particle Physics: Quarks" (PDF). Physics Letters B . 667 (1–5): 1. Bibcode:2008PhLB..667....1A. doi:10.1016/j.physletb.2008.07.018. hdl: 1854/LU-685594 .
  38. "Dark Energy Dark Matter". NASA Science: Astrophysics. 5 June 2015.
  39. Persic, Massimo; Salucci, Paolo (1 September 1992). "The baryon content of the Universe". Monthly Notices of the Royal Astronomical Society. 258 (1): 14P–18P. arXiv: astro-ph/0502178 . Bibcode:1992MNRAS.258P..14P. doi: 10.1093/mnras/258.1.14P . ISSN   0035-8711. S2CID   17945298.
  40. Satz, H.; Redlich, K.; Castorina, P. (2009). "The Phase Diagram of Hadronic Matter". The European Physical Journal C. 59 (1): 67–73. arXiv: 0807.4469 . Bibcode:2009EPJC...59...67C. doi:10.1140/epjc/s10052-008-0795-z. S2CID   14503972.
  41. Menezes, Débora P. (23 April 2016). "Modelling Hadronic Matter". Journal of Physics: Conference Series. 706 (3): 032001. Bibcode:2016JPhCS.706c2001M. doi: 10.1088/1742-6596/706/3/032001 .
  42. H.S. Goldberg; M.D. Scadron (1987). Physics of Stellar Evolution and Cosmology. Taylor & Francis. p. 202. ISBN   978-0-677-05540-4.
  43. H.S. Goldberg; M.D. Scadron (1987). Physics of Stellar Evolution and Cosmology. Taylor & Francis. p. 233. ISBN   978-0-677-05540-4.
  44. J.-P. Luminet; A. Bullough; A. King (1992). Black Holes . Cambridge University Press. p.  75. ISBN   978-0-521-40906-3.
  45. A. Bodmer (1971). "Collapsed Nuclei". Physical Review D . 4 (6): 1601. Bibcode:1971PhRvD...4.1601B. doi:10.1103/PhysRevD.4.1601.
  46. E. Witten (1984). "Cosmic Separation of Phases". Physical Review D . 30 (2): 272. Bibcode:1984PhRvD..30..272W. doi:10.1103/PhysRevD.30.272.
  47. C. Amsler; et al. (Particle Data Group) (2008). "Review of Particle Physics: Leptons" (PDF). Physics Letters B . 667 (1–5): 1. Bibcode:2008PhLB..667....1A. doi:10.1016/j.physletb.2008.07.018. hdl: 1854/LU-685594 .
  48. C. Amsler; et al. (Particle Data Group) (2008). "Review of Particle Physics: Neutrinos Properties" (PDF). Physics Letters B . 667 (1–5): 1. Bibcode:2008PhLB..667....1A. doi:10.1016/j.physletb.2008.07.018. hdl: 1854/LU-685594 .
  49. P.J. Collings (2002). "Chapter 1: States of Matter". Liquid Crystals: Nature's Delicate Phase of Matter. Princeton University Press. ISBN   978-0-691-08672-9.
  50. D.H. Trevena (1975). "Chapter 1.2: Changes of phase". The Liquid Phase. Taylor & Francis. ISBN   978-0-85109-031-3.
  51. National Research Council (US) (2006). Revealing the hidden nature of space and time. National Academies Press. p. 46. ISBN   978-0-309-10194-3.
  52. Tsan, U.C. (2012). "Negative Numbers And Antimatter Particles". International Journal of Modern Physics E. 21 (1): 1250005–1–1250005–23. Bibcode:2012IJMPE..2150005T. doi:10.1142/S021830131250005X. (From Abstract:) Antimatter particles are characterized by negative baryonic number A or/and negative leptonic number L. Materialization and annihilation obey conservation of A and L (associated to all known interactions)
  53. Smorra C.; et al. (20 October 2017). "A parts-per-billion measurement of the antiproton magnetic moment". Nature. 550 (7676): 371–374. Bibcode:2017Natur.550..371S. doi: 10.1038/nature24048 . PMID   29052625.
  54. Tsan, Ung Chan (2013). "Mass, Matter Materialization, Mattergenesis and Conservation of Charge". International Journal of Modern Physics E. 22 (5): 1350027. Bibcode:2013IJMPE..2250027T. doi:10.1142/S0218301313500274. (From Abstract:) Matter conservation melans conservation of baryonic number A and leptonic number L, A and L being algebraic numbers. Positive A and L are associated to matter particles, negative A and L are associated to antimatter particles. All known interactions do conserve matter
  55. J.P. Ostriker; P.J. Steinhardt (2003). "New Light on Dark Matter". Science. 300 (5627): 1909–13. arXiv: astro-ph/0306402 . Bibcode:2003Sci...300.1909O. doi:10.1126/science.1085976. PMID   12817140. S2CID   11188699.
  56. K. Pretzl (2004). "Dark Matter, Massive Neutrinos and Susy Particles". Structure and Dynamics of Elementary Matter. Walter Greiner. p. 289. ISBN   978-1-4020-2446-7.
  57. K. Freeman; G. McNamara (2006). "What can the matter be?". In Search of Dark Matter. Birkhäuser Verlag. p. 105. ISBN   978-0-387-27616-8.
  58. J.C. Wheeler (2007). Cosmic Catastrophes: Exploding Stars, Black Holes, and Mapping the Universe. Cambridge University Press. p. 282. ISBN   978-0-521-85714-7.
  59. J. Gribbin (2007). The Origins of the Future: Ten Questions for the Next Ten Years. Yale University Press. p. 151. ISBN   978-0-300-12596-2.
  60. P. Schneider (2006). Extragalactic Astronomy and Cosmology. Springer. p. 4, Fig. 1.4. ISBN   978-3-540-33174-2.
  61. T. Koupelis; K.F. Kuhn (2007). In Quest of the Universe . Jones & Bartlett Publishers. p.  492; Fig. 16.13. ISBN   978-0-7637-4387-1.
  62. M.H. Jones; R.J. Lambourne; D.J. Adams (2004). An Introduction to Galaxies and Cosmology. Cambridge University Press. p. 21; Fig. 1.13. ISBN   978-0-521-54623-2.
  63. 1 2 3 D. Majumdar (2007). Dark matter – possible candidates and direct detection. arXiv: hep-ph/0703310 .
  64. K.A. Olive (2003). "Theoretical Advanced Study Institute lectures on dark matter". arXiv: astro-ph/0301505 .
  65. K.A. Olive (2009). "Colliders and Cosmology". European Physical Journal C . 59 (2): 269–295. arXiv: 0806.1208 . Bibcode:2009EPJC...59..269O. doi:10.1140/epjc/s10052-008-0738-8. S2CID   15421431.
  66. J.C. Wheeler (2007). Cosmic Catastrophes. Cambridge University Press. p. 282. ISBN   978-0-521-85714-7.
  67. L. Smolin (2007). The Trouble with Physics. Mariner Books. p. 16. ISBN   978-0-618-91868-3.
  68. von Glasenapp, Helmuth (1999). Jainism: An Indian Religion of Salvation. Motilal Banarsidass Publ. p. 181. ISBN   978-81-208-1376-2.
  69. S. Toulmin; J. Goodfield (1962). The Architecture of Matter. University of Chicago Press. pp. 48–54.
  70. Discussed by Aristotle in Physics , esp. book I, but also later; as well as Metaphysics I–II.
  71. For a good explanation and elaboration, see R.J. Connell (1966). Matter and Becoming . Priory Press.
  72. H.G. Liddell; R. Scott; J.M. Whiton (1891). A lexicon abridged from Liddell & Scott's Greek–English lexicon. Harper and Brothers. p.  72. ISBN   978-0-19-910207-5.
  73. R. Descartes (1644). "The Principles of Human Knowledge". Principles of Philosophy I. p. 53.
  74. though even this property seems to be non-essential (René Descartes, Principles of Philosophy II [1644], "On the Principles of Material Things", no. 4.)
  75. R. Descartes (1644). "The Principles of Human Knowledge". Principles of Philosophy I. pp. 8, 54, 63.
  76. D.L. Schindler (1986). "The Problem of Mechanism". In D.L. Schindler (ed.). Beyond Mechanism. University Press of America.
  77. E.A. Burtt, Metaphysical Foundations of Modern Science (Garden City, New York: Doubleday and Company, 1954), 117–118.
  78. J.E. McGuire and P.M. Heimann, "The Rejection of Newton's Concept of Matter in the Eighteenth Century", The Concept of Matter in Modern Philosophy ed. Ernan McMullin (Notre Dame: University of Notre Dame Press, 1978), 104–118 (105).
  79. Isaac Newton, Mathematical Principles of Natural Philosophy, trans. A. Motte, revised by F. Cajori (Berkeley: University of California Press, 1934), pp. 398–400. Further analyzed by Maurice A. Finocchiaro, "Newton's Third Rule of Philosophizing: A Role for Logic in Historiography", Isis 65:1 (Mar. 1974), pp. 66–73.
  80. Isaac Newton, Optics, Book III, pt. 1, query 31.
  81. McGuire and Heimann, 104.
  82. 1 2 N. Chomsky (1988). Language and problems of knowledge: the Managua lectures (2nd ed.). MIT Press. p. 144. ISBN   978-0-262-53070-5.
  83. McGuire and Heimann, 113.
  84. M. Wenham (2005). Understanding Primary Science: Ideas, Concepts and Explanations (2nd ed.). Paul Chapman Educational Publishing. p.  115. ISBN   978-1-4129-0163-5.
  85. J.C. Maxwell (1876). Matter and Motion. Society for Promoting Christian Knowledge. p.  18. ISBN   978-0-486-66895-6.
  86. T.H. Levere (1993). "Introduction". Affinity and Matter: Elements of Chemical Philosophy, 1800–1865. Taylor & Francis. ISBN   978-2-88124-583-1.
  87. G.F. Barker (1870). "Introduction". A Text Book of Elementary Chemistry: Theoretical and Inorganic. John P. Morton and Company. p. 2.
  88. J.J. Thomson (1909). "Preface". Electricity and Matter. A. Constable.
  89. O.W. Richardson (1914). "Chapter 1". The Electron Theory of Matter. The University Press.
  90. M. Jacob (1992). The Quark Structure of Matter. World Scientific. ISBN   978-981-02-3687-8.
  91. V. de Sabbata; M. Gasperini (1985). Introduction to Gravitation. World Scientific. p. 293. ISBN   978-9971-5-0049-8.
  92. The history of the concept of matter is a history of the fundamental length scales used to define matter. Different building blocks apply depending upon whether one defines matter on an atomic or elementary particle level. One may use a definition that matter is atoms, or that matter is hadrons, or that matter is leptons and quarks depending upon the scale at which one wishes to define matter. B. Povh; K. Rith; C. Scholz; F. Zetsche; M. Lavelle (2004). "Fundamental constituents of matter". Particles and Nuclei: An Introduction to the Physical Concepts (4th ed.). Springer. ISBN   978-3-540-20168-7.
  93. 1 2 J. Allday (2001). Quarks, Leptons and the Big Bang. CRC Press. p. 12. ISBN   978-0-7503-0806-9.
  94. B.A. Schumm (2004). Deep Down Things: The Breathtaking Beauty of Particle Physics . Johns Hopkins University Press. p.  57. ISBN   978-0-8018-7971-5.
  95. See for example, M. Jibu; K. Yasue (1995). Quantum Brain Dynamics and Consciousness. John Benjamins Publishing Company. p. 62. ISBN   978-1-55619-183-1., B. Martin (2009). Nuclear and Particle Physics (2nd ed.). John Wiley & Sons. p. 125. ISBN   978-0-470-74275-4. and K.W. Plaxco; M. Gross (2006). Astrobiology: A Brief Introduction . Johns Hopkins University Press. p.  23. ISBN   978-0-8018-8367-5.
  96. P.A. Tipler; R.A. Llewellyn (2002). Modern Physics. Macmillan. pp. 89–91, 94–95. ISBN   978-0-7167-4345-3.
  97. P. Schmüser; H. Spitzer (2002). "Particles". In L. Bergmann; et al. (eds.). Constituents of Matter: Atoms, Molecules, Nuclei. CRC Press. pp. 773 ff. ISBN   978-0-8493-1202-1.
  98. P.M. Chaikin; T.C. Lubensky (2000). Principles of Condensed Matter Physics. Cambridge University Press. p. xvii. ISBN   978-0-521-79450-3.
  99. W. Greiner (2003). W. Greiner; M.G. Itkis; G. Reinhardt; M.C. Güçlü (eds.). Structure and Dynamics of Elementary Matter. Springer. p. xii. ISBN   978-1-4020-2445-0.
  100. P. Sukys (1999). Lifting the Scientific Veil: Science Appreciation for the Nonscientist . Rowman & Littlefield. p.  87. ISBN   978-0-8476-9600-0.
  101. B. Povh; K. Rith; C. Scholz; F. Zetsche; M. Lavelle (2004). "Fundamental constituents of matter". Particles and Nuclei: An Introduction to the Physical Concepts (4th ed.). Springer. ISBN   978-3-540-20168-7.

Further reading