Matter
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Matter is a general term for the substance of which physical objects are made.
[BOOK
], R. Penrose
, 1991
, The mass of the classical vacuum
, S. Saunders, H.R. Brown
, The Philosophy of Vacuum
,
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,
Oxford University Press, 0198244495
[WEB
], Matter (physics)
,
weblink, McGraw-Hill's Access Science: Encyclopedia of Science and Technology Online
, 2009-05-24
The term does not have single correct scientific meaning; different people in different fields use the term in different sometimes contradictory ways.{{cn}}Whereas "matter" originally (in
Aristotelian hylomorphism) referred not to an independent thing, but to a co-dependent "principle," the modern conception is that matter is a "
substance" or entity unto itself, that is to say, it exists even apart from composing something else. Modern science identifies this "substance" through its
physical properties; the most common current definition of
matter is anything that has
mass and occupies
volume.
[BOOK
, ] However, this definition has to be revised{{fact}} in light of
quantum mechanics, where the concept of "having mass", and "occupying space" are not as well-defined as in everyday life. A more general view is that bodies are made of
several substances, and the properties of matter (including mass and volume) are determined not only by the substances themselves, but by how they interact. In other words, matter is made up of interacting "building blocks",
[BOOK
, ][BOOK
, ] the so-called
particulate theory of matter.
[The particulate theory of matter dates back to Leucippus (~490 BC) and Democritus (~470–380 BC). See BOOK
, ]Matter is commonly said to exist in four
states (or
phases):
solid,
liquid,
gas and
plasma. However, advances in experimental technique have realized other phases, previously only theoretical constructs, such as
Bose–Einstein condensates and
Fermionic condensates. A focus on an elementary-particle view of matter also leads to new phases of matter, such as the
quark–gluon plasma.
[PRESS
, ]In
physics and
chemistry, matter exhibits both
wave-like and
particle-like properties, the so-called
wave–particle duality.
[BOOK
, ][BOOK
, ][BOOK
, ]In the realm of
cosmology, extensions of the term
matter are invoked to include
dark matter and
dark energy, concepts introduced to explain some odd phenomena of the
observable universe, such as the
galactic rotation curve. These exotic forms of "matter" do not refer to matter as "building blocks", but rather to currently poorly-understood forms of mass and energy.
[ARXIV
], D. Majumdar
, 2007
, Dark matter — possible candidates and direct detection
, hep-ph
, hep-ph/0703310
, Historical Development
Origins
The
pre-Socratics were among the first recorded speculators about the underlying nature of the visible world.
Thales (c. 624 BC–c. 546 BC) regarded water as the fundamental material of the world.
Anaximander (c. 610 BC–c. 546 BC) posited that the basic material was wholly characterless or limitless: the Infinite (
apeiron).
Anaximenes (flourished 585 BC, d. 528 BC) 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 BC) spoke of four basic materials of which everything was made: earth, water, air, and fire.
(1) Meanwhile,
Parmenides argued that change does not exist, and
Democritus that everything is composed of minuscule, inert bodies of all shapes called atoms. All of these notion had deep philosophical problems.
(2)Aristotle (384 BC – 322 BC) was the first to put the conception on a sound philosophical basis, which he did in his natural philosophy, especially in
Physics book I.
(3) He adopted as 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.The word Aristotle uses for matter,
ὑλη (hyle or hule), can be literally translated as wood or timber, that is, "raw material" for building.
(4) 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 exist in a whole (otherwise they would be independent wholes).
Early Modernity
René Descartes (1596–1650) was the originator of the modern conception of matter. Being a geometer, he redefined matter to be suitable for abstract, mathematical treatment as that which occupies space:{{quotation|So, extension in length, breadth, and depth, constitutes the nature of bodily substance; and thought constitutes the nature of thinking substance. And everything else which can be attributed to body presupposes extension, and is only a mode of that which is extended|René Descartes|Principles of Philosophy
(5)}}For Descartes, matter has only the property of extension, so its only activity aside from locomotion is to exclude other bodies: 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.
(6) They are independent things. In contrast, Aristotle defines matter and the formal/forming principle as complementary
principles which together compose one independent thing (
substance). In short, Aristotle defines matter (roughly speaking) as what things are made of, but Descartes elevates matter to be a thing in itself.The continuity and difference between Descartes' 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.
(7)Isaac Newton (1643–1727) inherited Descartes' mechanical conception of matter, but added to it. Newton restores to matter intrinsic properties in addition to extension (at least on a limited basis), such as mass. Newton viewed matter as "solid, massy, hard, impenetrable, movable particles", which were "even so very hard as never to wear or break in pieces."
[Newton's 31st query, as quoted by BOOK
], D.R. Oldroyd
, 1986
, The Arch of Knowledge: An Introductory Study of the History of the Philosophy and Methodology of Science
,
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,
Routledge, 0416013414
The "primary" properties of matter were amenable to mathematical description, unlike "secondary" qualities such as color or taste.
[ 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.][BOOK
], M. Wenham
, 2005
, Understanding Primary Science: Ideas, Concepts and Explanations
,
weblink, 115, 2nd
, Paul Chapman Educational Publishing
, 1412901634
{{anchor|note}}Later Developments
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. In the late 19th century with the discovery of the electron, and in the early 20th century, with the 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. Today, we know that even protons and neutrons are not indivisible, they can be divided into quarks, while electrons are part of a particle family called leptons. Both quarks and leptons are elementary particles, and are currently seen as being the fundamental constituents of matter.[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.BOOK
], B. Povh, K. Rith, C. Scholz, F. Zetsche, M. Lavelle
, 2004
, Particles and Nuclei: An Introduction to the Physical Concepts
, Fundamental constituents of matter
,
weblink, 4th
,
Springer (publisher), Springer, 3540201688
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).[BOOK
], J. Allday
, 2001
, Quarks, Leptons and the Big Bang
,
weblink, 12
,
CRC Press, 0750308060
Interactions between quarks and leptons are the result of an exchange of force-carrying particles (such as photons) between quarks and leptons.[BOOK
, ] The force-carrying particles are not themselves building blocks. As one consequence, mass and energy (which 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). Force carriers are usually not considered matter: the carriers of the electric force (photons) possess energy (see Planck relation) and the carriers of the weak force (W and Z bosons) are massive, but neither are considered matter either.[See for example, BOOK
, , BOOK
, and BOOK
, .] However, while these particles are not considered matter, they do contribute to the total mass of atoms, subatomic particles, and all systems which contain them.[BOOK
], P.A. Tipler, R.A. Llewellyn
, 2002
, Modern Physics
,
weblink, 89–91, 94–95
, 0716743450
,
Macmillan Publishers, Macmillan
[BOOK
], P. Schmüser, H. Spitzer
, 2002
, Particles
, L. Bergmann
et al., Constituents of Matter: Atoms, Molecules, Nuclei
,
weblink, 0849312027
, 773
ff,
CRC Press
Definitions
Common definition
Image:DNA chemical structure.svg|right|thumb|350px|The DNA moleculeDNA moleculeThe common definition of matter is anything that has both mass and volume (occupies space).[BOOK
, ][BOOK
], J.Kenkel, P.B. Kelter, D.S. Hage
, 2000
, Chemistry: An Industry-based Introduction with CD-ROM
,
weblink, 2
,
CRC Press, 1566703034
, All basic science textbooks define
matter as simply the collective aggregate of all material substances that occupy space and have mass or weight.
For example, a car would be said to be made of matter, as it occupies space, and has mass.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 Pauli exclusion principle.[BOOK
, ][BOOK
, ] 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. Amount of substance
The international standards organization Bureau International des Poids et Mesures (BIPM) uses the terminology "amount of substance", rather than "matter". To quote the SI brochure:[WEB
], SI brochure, Section 2.1.1.6 – Mole
,
weblink,
BIPM, 2009-04-30
"Amount of substance is defined to be proportional to the number of specified elementary entities in a sample, the proportionality constant being a universal constant which is the same for all samples. The unit of amount of substance is called the mole, symbol mol, and the mole is defined by specifying the mass of carbon 12 that constitutes one mole of carbon 12 atoms. By international agreement this was fixed at 0.012 kg, i.e. 12 g.
- 1. The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol".
- 2. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles."
Atoms and molecules definition
A definition of "matter" that is based upon its physical and chemical structure is: matter is made up of atoms and molecules. This definition is consistent with the BIPM definition of "amount of substance" above, but is more specific about the constituents of matter. (For further discussion, see the Discussion and background and Quarks and leptons definition sections). 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 and molecules definition. Alternatively, one can adopt the protons, neutrons and electrons definition. 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 protons, neutrons, and electrons.[BOOK
], M. de Podesta
, 2002
, Understanding the Properties of Matter
,
weblink, 8, 2nd
,
CRC Press, 0415257883
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 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 (see Quarks and leptons definition below). Quarks and leptons definition
Image:Standard Model of Elementary Particles.svg|thumb|250px|Under the "quarks and leptons" definition, the elementary and composite particles made of the quarks (in purple) and leptonsleptonsAs may be seen from 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 elementary fermions, namely quarks and leptons.[BOOK
], B. Povh, K. Rith, C. Scholz, F. Zetsche, M. Lavelle
, 2004
, Particles and Nuclei: An Introduction to the Physical Concepts
, Part I: Analysis: The building blocks of matter
,
weblink, 4th
, Springer
, 3540201688
[JOURNAL
], B. Carithers, P. Grannis
, 1995
, Discovery of the Top Quark
,
weblink,
SLAC,
Beam Line, 25, 3, 4–16
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 the two types of elementary fermions. 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.[See p.7 in JOURNAL
], B. Carithers, P. Grannis
, Discovery of the Top Quark
,
weblink,
SLAC,
Beam Line, 25, 3, 4–16
, 1995
(Higher generations particles quickly decay into first-generation particles, and thus are not commonly encountered.[BOOK
, ])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.[BOOK
], L. Smolin
, 2007
, The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next
,
weblink, 67
,
Mariner Books, 061891868X
. 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.[The W boson mass is 80.398 GeV; see Figure 1 in JOURNAL
, ] 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.[BOOK
], I.J.R. Aitchison, A.J.G. Hey
, 2004
, Gauge Theories in Particle Physics
,
weblink, 48
,
CRC Press, 0750308648
In other words most of what composes the "mass" of ordinary matter is due to the binding energy of quarks within protons and neutrons.[BOOK
], B. Povh, K. Rith, C. Scholz, F. Zetsche, M. Lavelle
, 2004
, Particles and Nuclei: An Introduction to the Physical Concepts
,
weblink, 103
,
Springer (publisher), Springer, 3540201688=
For example, the sum of the mass of the three quarks in a nucleon is approximately {{val|12.5|ul=MeV/c2}}, which is low compared to the mass of a nucleon (approximately {{val|938|ul=MeV/c2}}).[BOOK
, ][BOOK
], T. Hatsuda
, 2008
, Quark-gluon plasma and QCD
, H. Akai
, Condensed matter theories
,
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,
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The bottom line is that most of the mass of everyday objects comes from the interaction energy of its elementary components. Smaller building blocks?
“In the past, the search for building blocks of matter has led us to more and more 'elementary' entities – from the molecule to the atom, to the nucleus and electrons, to the nucleons, and eventually to the quarks. Have we completed this 'onion peeling' process ... ?”[BOOK
, ] 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 tauon and tauon neutrino.[BOOK
, ] “... the 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.” Discussion and background
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. James Clerk Maxwell discussed matter in his work Matter and Motion.[BOOK
, ] 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. 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.[BOOK
], T.H. Levere
, 1993
, Affinity and Matter: Elements of Chemical Philosophy, 1800–1865
, Introduction
,
weblink,
Taylor & Francis, 2881245838
A textbook discussion from 1870 suggests matter is what is made up of atoms:[BOOK
, ]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. The famous physicist J. J. Thomson wrote about the "constitution of matter" and was concerned with the possible connection between matter and electrical charge.[BOOK
, ] There is an entire literature concerning the "structure of matter", ranging from the "electrical structure" in the early 20th century,[BOOK
, ] to the more recent "quark structure of matter", introduced today with the remark: Understanding the quark structure of matter has been one of the most important advances in contemporary physics.[BOOK
, ] In this connection, physicists speak of matter fields, and speak of particles as "quantum excitations of a mode of the matter field".[BOOK
, ][BOOK
, ] 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 which, however, could be composed of more fundamental fermion fields)."[BOOK
, ]The term "matter" is used throughout physics in a bewildering variety of contexts: for example, one refers to "condensed matter physics",[BOOK
, ] "elementary matter",[BOOK
], W. Greiner
, 2003
, W. Greiner, M.G. Itkis, G. Reinhardt, M.C. Güçlü
, Structure and Dynamics of Elementary Matter
,
weblink,
Springer (publisher), Springer, xii
, 1402024452
"partonic" matter, "dark" matter, "anti"-matter, "strange" matter, and "nuclear" matter. In discussions of matter and antimatter, normal matter has been referred to by Alfvén as koinomatter.[BOOK
, ] It is fair to say that in physics, there is no broad consensus as to an exact definition of matter, and the term "matter" usually is used in conjunction with some modifier. Phases of ordinary matter
Image:Phase diagram for pure substance.JPG|thumb|250px||Phase diagram for a typical substance at a fixed volume. Vertical axis is Pressure, horizontal axis is Temperature. The green line marks the freezing point (above the green line is solid, below it is liquid) and the blue line the boiling point (above it is liquid and below it is gas). So, for example, at higher T, a higher P is necessary to maintain the substance in liquid phase. At the triple point the three phases; liquid, gas and solid; can coexist. Above the critical point there is no detectable difference between the phases. The dotted line shows the anomalous behavior of water: ice melts at constant temperature with increasing pressure.[BOOK
], S.R. Logan
, 1998
, Physical Chemistry for the Biomedical Sciences
,
weblink, 110–111
,
CRC Press, 0748407103
CRC Press{{seealso|Phase diagram|State of matter}}In
bulk, matter can exist in several different forms, or states of aggregation, known as
phases,
[BOOK
, ] depending on ambient
pressure,
temperature and
volume.
[BOOK
, ] 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).
Solid
Solids are characterized by a tendency to retain their structural integrity; if left on their own, they will not spread in the same way gas or liquids would. Many solids, like rocks and concrete, have very high
hardness and
rigidity and will tend to break or shatter when subject to various forms of
stress, but others like
steel and
paper are more
flexible and will bend. Solids are often composed of
crystals,
glasses, or
long chain molecules (e.g.
rubber and
paper). Some solids are
amorphous such as
glass. A common example of a solid is the solid form of water,
ice.
Liquid
In a liquid, the constituents frequently are touching, but able to move around each other. So unlike a gas, it has
cohesion and
viscosity. Compared to a solid, the forces holding constituents together are weaker, and it is not rigid, but adapts a shape decided by its container. Liquids are hard to compress. A common example is
water.
Gas
A gas is a state of aggregation without cohesion; a vapor. Thus a gas has no resistance to changing shape (beyond the inertia of its constituents, which have to be knocked aside). The distance between constituent particles is flexible, determined, for example, by the size of a container and the number of particles, not by internal forces. A common example is the vapor form of water,
steam.
Plasma
Plasma is a fourth state of matter consisting of an overall charge-neutral mix of electrons, ions and neutral atoms.
[BOOK
], T. Makabe, Z. Petrović
, 2006
, Plasma Electronics: Applications in Microelectronic Device Fabrication
,
weblink, 1
,
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The plasma exhibits behavior peculiar to long range
Coulomb forces in which the particles move in electromagnetic fields generated by and self-consistent with their own motions. The sun and stars are plasmas, as is the Earth's
ionosphere, and plasmas occur in neon signs. Plasmas of deuterium and tritium ions are used in
fusion reactions.
[BOOK
], C.K. Birdsall, A.B. Langdon
, 2005
, Plasma Physics via Computer Simulation
,
weblink, xvii
,
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The term
plasma was applied for the first time by
Tonks and
Langmuir in 1929, to the inner regions of a glowing ionized gas produced by electric discharge in a tube.
[BOOK
, ] Bose–Einstein condensate
This state of matter was first discovered by
Satyendra Nath Bose, who sent his work on statistics of photons to
Albert Einstein for comment. Following publication of Bose's paper, Einstein extended his treatment to massive particles fixed in number, and predicted this fifth state of matter in 1925. Bose–Einstein condensates were first realized experimentally by several different scientific groups in 1995 for rubidium, sodium, and lithium, using a combination of laser and evaporative cooling.
[BOOK
, ] Bose–Einstein condensation for atomic hydrogen was achieved in 1998.
[BOOK
, ]The Bose–Einstein condensate is a liquid-like
superfluid that occurs at low temperatures in which all atoms occupy the same quantum state. In low-density systems, it occurs at or below 10
−5 K.
Fermionic condensate
{{seealso|Superconductor|BCS theory}}A fermonic condensate is a superfluid phase formed by fermionic particles at low temperatures. It is closely related to the Bose–Einstein condensate under similar conditions. Unlike the Bose–Einstein condensates, fermionic condensates are formed using fermions instead of bosons. The earliest recognized fermionic condensate described the state of electrons in a superconductor; the physics of other examples including recent work with fermionic atoms is analogous. The first atomic fermionic condensate was created in 2003.[ARXIV
], M. Greiner, C.A. Regal, S. Jin
, 2003
, A molecular Bose–Einstein condensate emerges from a Fermi sea
, cond-mat.stat-mech
, cond-mat/0311172
, These atomic fermionic condensates are studied at temperatures in the vicinity of 50–350 nK.[ARXIV
], M.W. Zwierlein, C.H. Schunck, A. Schirotzek, W. Ketterle
, 2006
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, cond-mat/0605258
, cond-mat.supr-con
, A hypothetical fermionic condensate that appears in theories of massless fermions with chiral symmetry breaking is the chiral condensate or the quark condensate.[BOOK
, ]Image:Neutron star cross-section.JPG|280px|thumb|A model of a neutron star's internal structure. (Other models exist.[ BOOK
], P. Haensel, A.Y. Potekhin, A.Û. Potehin, D.G. Yakovlev
, 2007
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,
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,
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) At a depth of about 10 km the core becomes a superfluid liquid primarily of neutrons. The section at the left shows density vs. radius. Data from Luminet et al.[BOOK
], J.-P. Luminet, A. Bullough, A. King
, 1992
, Black Holes
,
weblink, 111, Fig. 25
,
Cambridge University Press, 0521409063
Cambridge University Press Core of a neutron star
{{seealso|Magnetar}}Because of its extreme density, the core of a neutron star falls under no other state of matter. While a white dwarf is about as massive as the sun (up to 1.4 solar masses, the
Chandrasekhar limit), the Pauli exclusion principle prevents its collapse to smaller radius, and it becomes an example of
degenerate matter. In contrast, neutron stars are between 1.5 and 3 solar masses, and achieve such density that the protons and electrons are crushed to become neutrons. Neutrons are fermions, so further collapse is prevented by the exclusion principle, forming so-called
neutron degenerate matter.
[BOOK
, ][BOOK
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, 2004
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File:Phases of Nuclear Matter.JPG|thumb|280px|Phases of nuclear matter; Compare with Siemens & Jensen.
[BOOK
], P.J. Siemens, A.S. Jensen
, 1994
, Elements Of Nuclei: Many-body Physics With The Strong Interaction
,
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,
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Westview Press
Quark–gluon plasma
{{seealso|Gluon|Hadron}}Gluons are elementary particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. The quark–gluon plasma is a hypothetical phase of matter, a phase of matter as yet not observed, supposed to exist in the early universe and to have evolved into a hadronic-gas phase.
[BOOK
, ] At extremely high energy the
strong force is anticipated to become so weak that the atomic nuclei break down into a bunch of loose quarks, which distinguishes the quark–gluon phase from normal plasma. In collisions of relativistic heavy ions, a phase transition occurs from the nuclear, hadronic phase to a matter phase consisting of quarks and gluons. So far, experimental results have shown that instead of a weakly interacting plasma, an almost ideal liquid is produced.
[PRESS
, ][JOURNAL
], W.A. Zajc
, 2008
, The fluid nature of quark–gluon plasma
,
Nuclear Physics A, 805, 283c–294c
, 10.1016/j.nuclphysa.2008.02.285
, {{arxiv, 0802.3552,
An animation can be found at
Gold ion collision @ RHIC.
Transparent Aluminum
In
2009, scientists from
Oxford University led an international team in using the FLASH laser synchrotron in
Hamburg, Germany to create a new state of matter, transparent
aluminum. Using a short pulse from the FLASH laser, they removed a core electron from each aluminium atom, but did not destroy or disrupt the metal’s crystalline structure. What resulted was an aluminum that was almost invisible to
ultraviolet radiation. Scientists involved in the discovery suggest that this will aid in further research concerning
planetary science and
nuclear fusion. The effect on the aluminum lasted for 40
femtoseconds.
[WEB
, ] Structure of ordinary matter
In particle physics, fermions are particles which obey
Fermi–Dirac statistics. Fermions can be elementary, like the electron, or composite, like the proton and the neutron. In the
Standard Model there are two types of elementary fermions: quarks and leptons, which are discussed next.
Quarks
Quarks are a particles of
spin-{{frac|1|2}}, implying that they are
fermions. They carry an
electric charge of −{{frac|1|3}}
e (down-type quarks) or +{{frac|2|3}} 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. Quarks are massive particles, and therefore are also subject to
gravity.{| class="wikitable" border="1" style="margin:0 auto; text-align:center;"|+Quark properties
[JOURNAL
, ]! name !! symbol !! spin !! electric charge
(
e) !! mass
(
MeV/
c2) !! mass comparable to !! antiparticle !! antiparticle
symbol
|
| up-type quarks |
|
| Up quark>up | Up quark}} | 1|2}} | 2|3}}| 1.5 to 3.3| ~ 5 electrons| antiup | Up antiquark}} |
|
| Charm quark>charm | Charm quark}} | 1|2}} | 2|3}}| 1160 to 1340| ~ 1 proton| anticharm | Charm antiquark}} |
|
| Top quark>top | Top quark}} | 1|2}} | 2|3}}| 169,100 to 173,300| ~ 180 protons or |
~ 1 tungsten atom| antitopTop antiquark}} |
|
| down-type quarks |
|
| Down quark>down | Down quark}} | 1|2}} | 1|3}}| 3.5 to 6.0| ~ 10 electrons| antidown | Down antiquark}} |
|
| Strange quark>strange | Strange quark}} | 1|2}} | 1|3}}| 70 to 130| ~ 200 electrons| antistrange | Strange antiquark}} |
|
| Bottom quark>bottom | Bottom quark}} | 1|2}} | 1|3}}| 4130 to 4370| ~ 5 protons| antibottom | Bottom antiquark}} |
thumb|120px|Quark structure of a proton: 2 up quarks and 1 down quark. Baryonic matter
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 is usually used to refer to triquarks — particles made of three quarks. "Exotic" baryons made of four quarks and one antiquark are known as the 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 baryionic matter. About 23% is dark matter, and about 72% is dark energy.[WEB
], 2008
, Five Year Results on the Oldest Light in the Universe
,
weblink,
NASA, 2008-05-02
File:Size IK Peg.svg|250px|thumb|A comparison between the white dwarf IK PegasiIK Pegasi Degenerate matter
In physics, degenerate matter refers to the ground state of a gas of fermions at a temperature near absolute zero.[BOOK
], H.S. Goldberg, M.D. Scadron
, 1987
, Physics of Stellar Evolution and Cosmology
,
weblink, 202
,
Taylor & Francis, 0677055404
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 for the case of many fermions the maximum kinetic energy called the Fermi energy and the pressure of the gas becomes very large and dependent upon 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.[BOOK
], H.S. Goldberg, M.D. Scadron
, 1987
, Physics of Stellar Evolution and Cosmology
,
weblink, 233
,
Taylor & Francis, 0677055404
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.[BOOK
, ]Degenerate matter includes the part of the universe that is made up of neutron stars and white dwarfs. Strange matter
Strange matter is a particular form of quark matter, usually thought of as a 'liquid' of up, down, and strange quarks. It is to be 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 containing 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 of the term "strange matter"
In particle physics and astrophysics, the term is used in two ways, one broader and the other more specific.
- 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).
- 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
JOURNAL
, A. Bodmer
, 1971
, Collapsed Nuclei
,
Physical Review D, 4, 6, 1601
, 10.1103/PhysRevD.4.1601
[JOURNAL
], E. Witten
, 1984
, Cosmic Separation of Phases
,
Physical Review D, 30, 2, 272
, 10.1103/PhysRevD.30.272
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
Leptons are a particles of spin-{{frac|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 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.{| class="wikitable" border="1" style="margin:0 auto; text-align:center;"|+Lepton properties! name !! symbol !! spin !! electric charge
(e) !! mass
(MeV/c2) !! mass comparable to !! antiparticle !! antiparticle
symbol|
| charged leptons | [JOURNAL
, ]
|
| electron| electron}} | 1|2}}| −1| 0.5110| 1 electron| antielectron | antielectron}} |
|
| muon| muon}} | 1|2}}| −1| 105.7| ~ 200 electrons| antimuon | antimuon}} |
|
| tauon| tauon}} | 1|2}}| −1| 1,777| ~ 2 protons| antitauon | antitauon}} |
|
| neutrinos | [JOURNAL
, ]
|
| electron neutrino| Electron neutrino}} | 1|2}}| 0| | < 0.0004601|1000}} electron| electron antineutrino | Electron antineutrino}} |
|
| muon neutrino| Muon neutrino}} | 1|2}}| 0| | < 0.191|2}} electron| muon antineutrino | Muon antineutrino}} |
|
| tauon neutrino| Tauon neutrino}} | 1|2}}| 0| | < 18.2| < 40 electrons| tauon antineutrinoTauon antineutrino}} |
Antimatter
{{unsolved|physics|Baryon asymmetry. Why is there far more matter than antimatter in the observable universe? }}In particle physics and quantum chemistry, 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 Einstein's equation {{nowrap|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.Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities (as the result of radioactive decay or cosmic rays). This is because antimatter which 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, and whether other places are almost entirely antimatter 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 the charge parity (or CP symmetry) violation. CP symmetry violation can be obtained from the Standard Model,[BOOK
, ] 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. Other types of matter
Image:Matter Distribution.JPG|thumb |300px |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.[ARXIV
], J.P. Ostriker, P.J. Steinhardt
, 2003
, New Light on Dark Matter
, astro-ph
, astro-ph/0306402
(
, For more information, see NASA.)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[BOOK
], K. Pretzl
, 2004
, Dark Matter, Massive Neutrinos and Susy Particles
,
weblink, Structure and Dynamics of Elementary Matter
, 289
,
Walter Greiner, 1402024460
[BOOK
], K. Freeman, G. McNamara
, 2006
, What can the matter be?
,
weblink, In Search of Dark Matter
, 105
,
Birkhäuser, 0387276165
and 73% is dark energy.[BOOK
, ][BOOK
, ]File:Rotation curve (Milky Way).JPG|thumb |300px |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.[BOOK
, ][BOOK
, ][BOOK
], M.H. Jones, R.J. Lambourne, D.J. Adams
, 2004
, An Introduction to Galaxies and Cosmology
,
weblink, 21; Fig. 1.13
,
Cambridge University Press, 0521546230
Cambridge University Press Dark matter
{{seealso|Galaxy formation and evolution|Dark matter halo}}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.
[ARXIV
], D. Majumdar
, 2007
, Dark matter — possible candidates and direct detection
, hep-ph
, hep-ph/0703310
, [ARXIV
], K.A. Olive
, 2003
, Theoretical Advanced Study Institute lectures on dark matter
, astro-ph
, astro-ph/0301505
, Observational evidence of the early universe and the
big bang theory require that this matter have energy and mass, but is not composed of either elementary fermions (as above) OR gauge bosons. 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,][JOURNAL
], K.A. Olive
, 2009
, Colliders and Cosmology
,
European Physical Journal C, 59, 269–295
, 10.1140/epjc/s10052-008-0738-8
, {{arxiv, 0806.1208,
which are not Standard Model particles, but relics formed at very high energies in the early phase of the universe and still floating about. Dark energy
{{seealso|Big bang#Dark energy}}In cosmology, dark energy is the name given to the antigravitating influence that is accelerating the rate of expansion of the universe. It is known not to be composed of known particles like protons, neutrons or electrons, nor of the particles of dark matter, because these all gravitate.[BOOK
, ][BOOK
, ]{{Quotation|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: The Trouble with Physics, p. 16}} Exotic matter
Exotic matter is a hypothetical concept of particle physics. It covers any material which violates one or more classical conditions or is not made of known baryonic particles. Such materials would possess qualities like negative mass or being repelled rather than attracted by gravity. References
-
[Stephen Toulmin and June Goodfield, The Architecture of Matter (Chicago: University of Chicago Press, 1962), 48-54.]
-
[Discussed by Aristotle in Physics, esp. book I, but also later; as well as Metaphysics I-II.]
-
[See Richard J. Connell, Matter and Becoming (Chicago: The Priory Press, 1966) for a good explanation and elaboration.]
-
[Henry George Liddell, Robert Scott, James Morris Whiton, A lexicon abridged from Liddell & Scott's Greek-English lexicon (New York: Harper and Brothers, 1891), 725.]
-
[René Descartes Principles of Philosophy I (1644) “The Principles of Human Knowledge,” 53.]
-
[Ibid, 8, 54, 63.]
-
[David L. Schindler, "The Problem of Mechanism," Beyond Mechanism, ed. David L. Schindler (University Press of America, 1986).]
Further reading
- BOOK, The Rise of the Standard Model, Lillian Hoddeson, Michael Riordan, 0521578167, Cambridge University Press, 1997,weblink
- BOOK, Hidden Worlds, The search for quarks in ordinary matter, Timothy Paul Smith, 1,weblink 0691057737, 2004, Princeton University Press,
- BOOK, Elementary Particles: Building blocks of matter, 9812561412, 2005, World Scientific, Harald Fritzsch,weblink 1,
- BOOK, A Critical Exposition of the Philosophy of Leibniz, Bertrand Russell,weblink 88, The philosophy of matter, 041508296X, 1992, Reprint of 1937 2nd, Routledge,
- Stephen Toulmin and June Goodfield, The Architecture of Matter (Chicago: University of Chicago Press, 1962).
- Richard J. Connell, Matter and Becoming (Chicago: The Priory Press, 1966).
- Ernan McMullin, The Concept of Matter in Greek and Medieval Philosophy (Notre Dame, IN: Univ. of Notre Dame Press, 1965).
- Ernan McMullin, The Concept of Matter in Modern Philosophy (Notre Dame, IN: University of Notre Dame Press, 1978).
See also
{{Col-begin}}{{Col-1-of-5}}Antimatter
{{Col-2-of-5}}Cosmology
{{Col-3-of-5}}Dark matter
{{Col-4-of-5}}Philosophy
Other
{{col-5-of-5}}{hide}Wikipedia-Books
|1=Matter
|3=Hadronic Matter
{edih}{{col-end}} External links
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