WikiPortallus: Matter.html

In common usage, matter is anything that has both mass and volume (takes up space). A more rigourous definition is used in science: matter is what atoms and molecules are made of. Matter is commonly is said to come in three states (phases); solids, liquids and gases. However additional phases exists such as plasmas and Bose-Einstein condensates.

Matter, in the scientific definition, constitutes about 4% of the energy of the observable universe. The remaining energy is thought to be due to exotic and poorly understood forms, of which 23% is dark matter²³ and 73% is dark energy.⁴⁵

Definitions

Common definition

The common definition of matter is anything that has both mass and volume (occupies space).⁶ For example, a car would be said to be made of matter, as it occupies space, and has mass.

Scientific definition

An almost unrelated definition based upon physics and chemistry is: what atoms and molecules are made of, meaning anything made of protons, neutrons, and electrons. As an example of matter under this definition, genetic information is carried by a long molecule called DNA, which is copied and inherited across generations.

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.⁷ 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.⁸ 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. Thompson wrote about the "constitution of matter" and was concerned with the possible connection between matter and electrical charge.⁹ There is an entire literature concerning the "structure of matter", ranging from the "electrical structure" in the early 20th century¹⁰, 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.¹¹ In this connection, physicists speak of matter fields, and speak of particles as "quantum excitations of a mode of the matter field".¹²¹³ 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..."¹⁴

The term "matter" is used throughout physics in a bewildering variety of contexts: for example, one refers to "condensed matter physics",¹⁵ "elementary matter",¹⁶ "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.¹⁷ 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.

Quarks and leptons definition

As 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". The "scientific definition" stated above follows this tradition. In a more technical version it can be stated as: ordinary matter is everything that is composed of elementary fermions, namely quarks and leptons.¹⁸¹⁹ 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. Since 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. Since electrons are leptons, and protons and neutrons are made of quarks, this leads to the definition of matter as being "quarks and leptons", which are the two elementary types of fermions. Carithers and Grannis state: Ordinary matter is composed entirely of first-generation particles, namely the u [up] and d [down] quarks, plus the electron and its neutrino.²⁰

This definition of ordinary matter means that mass is not something that is exclusive to ordinary matter. Some massive particles such as the W and Z bosons are not made of quarks and leptons. Thus, the quark-lepton definition of ordinary matter leads to "two groups" of particles, ordinary matter (quarks and leptons) and force carriers (gauge bosons).

Phases of ordinary matter

In bulk, matter can exist in several different forms known as phases, depending on ambient pressure and temperature. 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, ...). 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 small quantities, matter can exhibit properties that are entirely different from those of bulk material and may not be well described by any 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 solids).

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).

Liquid

In a liquid, the molecules are frequently touching, but able to move around each other. So unlike a gas, it has cohesion and viscosity. While unlike a solid, it is not highly rigid.

Gas

A gas is a substance composed of small molecules which are spaced far enough apart from each other that they rarely interact and do not impeded each others' motion. Thus a gas has no resistance to changing shape (beyond the inertia of the molecules which have to be knocked aside).

Plasma

A plasma is a state of matter found in stars, lightning, and neon signs. The plasma phase is the most abundant state of matter in the universe.^{citation needed}

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.²¹ Bose-Einstein condensation for atomic hydrogen was achieved in 1998.²²

The Bose-Einstein condensate is a liquid-like superfluid that occurs in at low temperatures in which all atoms occupy the same quantum state. In low-density systems, it occurs at or below 10⁻⁵ K.²²

Fermonic condensate

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 by Deborah S. Jin in 2003.²³ A chiral condensate is an example of a fermionic condensate that appears in theories of massless fermions with chiral symmetry breaking.

Core of a neutron star

Because of its extreme density, the core of a neutron star falls under no other state of matter.

Quark-gluon plasma

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. 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, it is hoped to observe a phase transition from the nuclear, hadronic phase to a matter phase consisting of quarks and gluons. So far, experimental results have shown that such collisions form a dense hadronic fireball of high energy density well localized in space.²⁴ An animation is found at Gold ion collision @ RHIC.

Structure of ordinary matter

Quarks

Quarks are a particles of spin-¹⁄₂, meaning that they are fermions. They carry an electric charge of −¹⁄₃ e (down-type quarks) or +²⁄₃ e (up-type quarks). For comparison, an electron has 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.

Baryonic matter

Baryonic matter is the part of the universe that is made of baryons (including all atoms). 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. 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.²⁶

Leptons

Leptons are a particles of spin-¹⁄₂, meaning that they are fermions. They carry an electric charge of −1 e (electron-like 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.

Other types of matter

Antimatter

In particle physics and quantum chemistry, antimatter is matter that is composed of the antiparticles of those that constitute normal 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 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, whether other places are almost entirely antimatter instead, and what might be possible if antimatter could be harnessed, 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.

Dark matter

In cosmology, effects at the largest scales seem to indicate the presence of incredible amounts of dark matter which is not associated with electromagnetic radiation. 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. As such, it is composed of particles as yet unobserved in the laboratory (perhaps supersymmetric particles).

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...

References

^ Jeremiah P. Ostriker and Paul Steinhardt New Light on Dark Matter
^ K Pretzl (2004). "Dark Matter, Massive Neutrinos and Susy Particles". Structure and Dynamics of Elementary Matter (Walter Greiner ed.). p.289. ISBN 1402024460, http://books.google.com/books?id=lokz2n-9gX0C&pg=PA289&dq=matter+%22massive+particles%22&lr=&as_brr=0.
^ Ken Freeman, Geoff McNamara (2006). "What can the matter be?". In Search of Dark Matter, Birkhäuser. p.105. ISBN 0387276165, http://books.google.com/books?id=C2OS1kmQ8JIC&pg=PA45&dq=isbn:0387276165#PPA105,M1.
^ J. Craig Wheeler (2007). Cosmic Catastrophes: Exploding Stars, Black Holes, and Mapping the Universe, Cambridge University Press. p.282. ISBN 0521857147, http://books.google.com/books?id=j1ej8d0F8jAC&pg=PA282&dq=%22dark+energy%22+date:2002-2009&lr=&as_brr=0.
^ John Gribbin (2007). The Origins of the Future: Ten Questions for the Next Ten Years, Yale University Press. p.151. ISBN 0300125968, http://books.google.com/books?id=f6AYrZYGig8C&pg=PA151&dq=%22dark+energy%22+date:2002-2009&lr=&as_brr=0.
^ Sally M Walker & Andy King (2005). What is Matter?, Lerner Publications. p.7. ISBN 0822551314, http://books.google.com/books?id=o7EquxOl4MAC&printsec=frontcover&dq=matter&lr=&as_brr=0#PPA7,M1.
^ James Clerk Maxwell (1876). Matter and Motion, Society for Promoting Christian Knowledge. p.18, http://books.google.com/books?id=MWoOAAAAIAAJ&printsec=frontcover&dq=matter&lr=&as_brr=0#PPA18,M1.
^ Trevor Harvey Levere (1993). "Introduction". Affinity and Matter: Elements of Chemical Philosophy, 1800-1865, Taylor & Francis. ISBN 2881245838, http://books.google.com/books?id=gKSDWsE8fZMC&printsec=frontcover&dq=matter&lr=&as_brr=0#PPA14,M1.
^ Joseph John Thomson (1909). "Preface". Electricity and Matter, A. Constable, http://books.google.com/books?id=2AaToepvKoEC&printsec=titlepage#PPP13,M1.
^ Owen Willans Richardson (1914). "Chapter 1". The Electron Theory of Matter, The University Press, http://books.google.com/books?id=RpdDAAAAIAAJ&printsec=frontcover&dq=matter&lr=&as_brr=0#PPA1,M1.
^ Maurice Jacob (1992). The Quark Structure of Matter: proceedings of a topical European meeting in the Rhine Valley : Strasbourgh-Karlsruhe, 26 September-1 October 1985, World Scientific. ISBN 9810236875, http://books.google.com/books?id=iQ1e2a9bPikC&printsec=frontcover&dq=matter&lr=&as_brr=0#PPA1,M1.
^ P. C. W. Davies (1979). The Forces of Nature, Cambridge University Press. p.116. ISBN 052122523X, http://books.google.com/books?id=Av08AAAAIAAJ&pg=PA116&dq=%22matter+field%22&lr=&as_brr=0.
^ Steven Weinberg (1998). The Quantum Theory of Fields, Cambridge University Press. p.2. ISBN 0521550025, http://books.google.com/books?id=2oPZJJerMLsC&pg=PA5&dq=Weinberg+%22matter+field%22&lr=&as_brr=0#PPA5,M1.
^ Venzo De Sabbata, Maurizio Gasperini (1985). Introduction to Gravitation, World Scientific. p.293. ISBN 9971500493, http://books.google.com/books?id=7sJ6m8s0_ccC&pg=PA293&dq=Weinberg+%22matter+field%22&lr=&as_brr=0.
^ P. M. Chaikin, T. C. Lubensky (2000). Principles of Condensed Matter Physics, Cambridge University Press. p.xvii. ISBN 0521794501, http://books.google.com/books?id=P9YjNjzr9OIC&printsec=frontcover&dq=matter&lr=&as_brr=0#PPR17,M1.
^ Walter Greiner, Mikhail G. Itkis (2003). Structure and Dynamics of Elementary Matter: Proceedings of the NATO Asi on Structure and Dynamics of Elementary Matter, Camyuva-Kemer (Antalya), Turkey, from 22 September to 2 October 2003, Springer. ISBN 1402024452, http://books.google.com/books?id=ORyJzhAzpUgC&printsec=frontcover&dq=matter&lr=&as_brr=0#PPR12,M1.
^ Paul Sukys (1999). Lifting the Scientific Veil: Science Appreciation for the Nonscientist, Rowman & Littlefield. p.87. ISBN 0-847-69600-6, http://books.google.com/books?id=WEM4hqxJ-xYC&pg=PR23&dq=isbn:0847696006#PPA87,M1.
^ Povh, Rith, Scholz, Zetche, Reigthinger Particles and Nuclei, 1999, ISBN 3540438238
^ B. Carithers, P Grannis (1995). "Discovery of the Top Quark". Beam Line (SLAC) 25 (3): 4–16, http://www.slac.stanford.edu/pubs/beamline/pdf/95iii.pdf.
^ See p. 7 in B. Carithers, P Grannis (1995). "Discovery of the Top Quark". Beam Line (SLAC) 25 (3): 4-16, http://www.slac.stanford.edu/pubs/beamline/pdf/95iii.pdf.
^ Gordon Fraser (2006). The New Physics for the Twenty-first Century, Cambridge University Press. p.238. ISBN 0521816009, http://books.google.com/books?id=0idvEIXwfxsC&pg=PA238&dq=%22Bose-Einstein+condensate%22&lr=&as_brr=0#PPA238,M1.
^ ^a ^b Christopher Pethick, Henrik Smith (2002). "Introduction". Bose-Einstein Condensation in Dilute Gases, Cambridge University Press. ISBN 0521665809, http://books.google.com/books?id=K_KPhpTTmkEC&printsec=frontcover&dq=%22Bose-Einstein+condensate%22&lr=&as_brr=0#PPA1,M1.
^ Markus Greiner, Cindy A. Regal, and Deborah S. Jin A molecular Bose-Einstein condensate emerges from a Fermi sea
^ Jean Letessier, Johann Rafelski (2002). "A New Phase of Matter?". Hadrons and Quark-gluon Plasma, Cambridge University Press. ISBN 0521385369, http://books.google.com/books?id=vSnFPyQaSTsC&printsec=frontcover&dq=%22gluon+plasma%22&lr=&as_brr=0#PPA8,M1.
^ C. Amsler et al. (Particle Data Group), PL B667, 1 (2008) (URL: http://pdg.lbl.gov/2008/tables/rpp2008-sum-quarks.pdf)
^ "Five Year Results on the Oldest Light in the Universe". NASA (2008). Retrieved on May 2, 2008.
^ C. Amsler et al. (Particle Data Group), PL B667, 1 (2008) (URL: http://pdg.lbl.gov/2008/tables/rpp2008-sum-leptons.pdf)
^ C. Amsler et al. (Particle Data Group), PL B667, 1 (2008) (URL: http://pdg.lbl.gov/2008/listings/s066.pdf)

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