QCD matter

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/QCD_matter 

Quark matter or QCD matter (quantum chromodynamic) refers to any of a number of hypothetical phases of matter whose degrees of freedom include quarks and gluons, of which the prominent example is quark-gluon plasma. Several series of conferences in 2019, 2020, and 2021 were devoted to this topic.

Quarks are liberated into quark matter at extremely high temperatures and/or densities, and some of them are still only theoretical as they require conditions so extreme that they cannot be produced in any laboratory, especially not at equilibrium conditions. Under these extreme conditions, the familiar structure of matter, where the basic constituents are nuclei (consisting of nucleons which are bound states of quarks) and electrons, is disrupted. In quark matter it is more appropriate to treat the quarks themselves as the basic degrees of freedom.

In the standard model of particle physics, the strong force is described by the theory of QCD. At ordinary temperatures or densities this force just confines the quarks into composite particles (hadrons) of size around 10⁻¹⁵ m = 1 femtometer = 1 fm (corresponding to the QCD energy scale Λ_QCD ≈ 200 MeV) and its effects are not noticeable at longer distances.

However, when the temperature reaches the QCD energy scale (T of order 10¹² kelvins) or the density rises to the point where the average inter-quark separation is less than 1 fm (quark chemical potential μ around 400 MeV), the hadrons are melted into their constituent quarks, and the strong interaction becomes the dominant feature of the physics. Such phases are called quark matter or QCD matter.

The strength of the color force makes the properties of quark matter unlike gas or plasma, instead leading to a state of matter more reminiscent of a liquid. At high densities, quark matter is a Fermi liquid, but is predicted to exhibit color superconductivity at high densities and temperatures below 10¹² K.

Unsolved problem in physics:

QCD in the non-perturbative regime: quark matter. The equations of QCD predict that a sea of quarks and gluons should be formed at high temperature and density. What are the properties of this phase of matter?

Occurrence

Natural occurrence

• According to the Big Bang theory, in the early universe at high temperatures when the universe was only a few tens of microseconds old, the phase of matter took the form of a hot phase of quark matter called the quark–gluon plasma (QGP).
• Compact stars (neutron stars). A neutron star is much cooler than 10¹² K, but gravitational collapse has compressed it to such high densities, that it is reasonable to surmise that quark matter may exist in the core. Compact stars composed mostly or entirely of quark matter are called quark stars or strange stars.
• QCD matter may exist within the collapsar of a gamma-ray burst, where temperatures as high as 6.7 x 10¹³ K may be generated.

At this time no star with properties expected of these objects has been observed, although some evidence has been provided for quark matter in the cores of large neutron stars.

• Strangelets. These are theoretically postulated (but as yet unobserved) lumps of strange matter comprising nearly equal amounts of up, down and strange quarks. Strangelets are supposed to be present in the galactic flux of high energy particles and should therefore theoretically be detectable in cosmic rays here on Earth, but no strangelet has been detected with certainty.
• Cosmic ray impacts. Cosmic rays comprise a lot of different particles, including highly accelerated atomic nuclei, particularly that of iron.

Laboratory experiments suggests that the inevitable interaction with heavy noble gas nuclei in the upper atmosphere would lead to quark–gluon plasma formation.

• Quark matter with baryon number over about 300 may be more stable than nuclear matter. This form of baryonic matter could possibly form a continent of stability.

Laboratory experiments

Particle debris trajectories from one of the first lead-ion collisions with the LHC, as recorded by the ALICE detector. The extremely brief appearance of quark matter in the point of collision is inferred from the statistics of the trajectories.

Even though quark-gluon plasma can only occur under quite extreme conditions of temperature and/or pressure, it is being actively studied at particle colliders, such as the Large Hadron Collider LHC at CERN and the Relativistic Heavy Ion Collider RHIC at Brookhaven National Laboratory.

In these collisions, the plasma only occurs for a very short time before it spontaneously disintegrates. The plasma's physical characteristics are studied by detecting the debris emanating from the collision region with large particle detectors. 

Heavy-ion collisions at very high energies can produce small short-lived regions of space whose energy density is comparable to that of the 20-micro-second-old universe. This has been achieved by colliding heavy nuclei such as lead nuclei at high speeds, and a first time claim of formation of quark–gluon plasma came from the SPS accelerator at CERN in February 2000.

This work has been continued at more powerful accelerators, such as RHIC in the US, and as of 2010 at the European LHC at CERN located in the border area of Switzerland and France. There is good evidence that the quark–gluon plasma has also been produced at RHIC.

Thermodynamics

The context for understanding the thermodynamics of quark matter is the standard model of particle physics, which contains six different flavors of quarks, as well as leptons like electrons and neutrinos. These interact via the strong interaction, electromagnetism, and also the weak interaction which allows one flavor of quark to turn into another. Electromagnetic interactions occur between particles that carry electrical charge; strong interactions occur between particles that carry color charge.

The correct thermodynamic treatment of quark matter depends on the physical context. For large quantities that exist for long periods of time (the "thermodynamic limit"), we must take into account the fact that the only conserved charges in the standard model are quark number (equivalent to baryon number), electric charge, the eight color charges, and lepton number. Each of these can have an associated chemical potential. However, large volumes of matter must be electrically and color-neutral, which determines the electric and color charge chemical potentials. This leaves a three-dimensional phase space, parameterized by quark chemical potential, lepton chemical potential, and temperature.

In compact stars quark matter would occupy cubic kilometers and exist for millions of years, so the thermodynamic limit is appropriate. However, the neutrinos escape, violating lepton number, so the phase space for quark matter in compact stars only has two dimensions, temperature (T) and quark number chemical potential μ. A strangelet is not in the thermodynamic limit of large volume, so it is like an exotic nucleus: it may carry electric charge.

A heavy-ion collision is in neither the thermodynamic limit of large volumes nor long times. Putting aside questions of whether it is sufficiently equilibrated for thermodynamics to be applicable, there is certainly not enough time for weak interactions to occur, so flavor is conserved, and there are independent chemical potentials for all six quark flavors. The initial conditions (the impact parameter of the collision, the number of up and down quarks in the colliding nuclei, and the fact that they contain no quarks of other flavors) determine the chemical potentials.

Phase diagram

Conjectured form of the phase diagram of QCD matter, with temperature on the vertical axis and quark chemical potential on the horizontal axis, both in mega-electron volts.

The phase diagram of quark matter is not well known, either experimentally or theoretically. A commonly conjectured form of the phase diagram is shown in the figure to the right. It is applicable to matter in a compact star, where the only relevant thermodynamic potentials are quark chemical potential μ and temperature T.

For guidance it also shows the typical values of μ and T in heavy-ion collisions and in the early universe. For readers who are not familiar with the concept of a chemical potential, it is helpful to think of μ as a measure of the imbalance between quarks and antiquarks in the system. Higher μ means a stronger bias favoring quarks over antiquarks. At low temperatures there are no antiquarks, and then higher μ generally means a higher density of quarks.

Ordinary atomic matter as we know it is really a mixed phase, droplets of nuclear matter (nuclei) surrounded by vacuum, which exists at the low-temperature phase boundary between vacuum and nuclear matter, at μ = 310 MeV and T close to zero. If we increase the quark density (i.e. increase μ) keeping the temperature low, we move into a phase of more and more compressed nuclear matter. Following this path corresponds to burrowing more and more deeply into a neutron star.

Eventually, at an unknown critical value of μ, there is a transition to quark matter. At ultra-high densities we expect to find the color-flavor-locked (CFL) phase of color-superconducting quark matter. At intermediate densities we expect some other phases (labelled "non-CFL quark liquid" in the figure) whose nature is presently unknown. They might be other forms of color-superconducting quark matter, or something different.

Now, imagine starting at the bottom left corner of the phase diagram, in the vacuum where μ = T = 0. If we heat up the system without introducing any preference for quarks over antiquarks, this corresponds to moving vertically upwards along the T axis. At first, quarks are still confined and we create a gas of hadrons (pions, mostly). Then around T = 150 MeV there is a crossover to the quark gluon plasma: thermal fluctuations break up the pions, and we find a gas of quarks, antiquarks, and gluons, as well as lighter particles such as photons, electrons, positrons, etc. Following this path corresponds to travelling far back in time (so to say), to the state of the universe shortly after the big bang (where there was a very tiny preference for quarks over antiquarks).

The line that rises up from the nuclear/quark matter transition and then bends back towards the T axis, with its end marked by a star, is the conjectured boundary between confined and unconfined phases. Until recently it was also believed to be a boundary between phases where chiral symmetry is broken (low temperature and density) and phases where it is unbroken (high temperature and density). It is now known that the CFL phase exhibits chiral symmetry breaking, and other quark matter phases may also break chiral symmetry, so it is not clear whether this is really a chiral transition line. The line ends at the "chiral critical point", marked by a star in this figure, which is a special temperature and density at which striking physical phenomena, analogous to critical opalescence, are expected.

For a complete description of phase diagram it is required that one must have complete understanding of dense, strongly interacting hadronic matter and strongly interacting quark matter from some underlying theory e.g. quantum chromodynamics (QCD). However, because such a description requires the proper understanding of QCD in its non-perturbative regime, which is still far from being completely understood, any theoretical advance remains very challenging.

Theoretical challenges: calculation techniques

The phase structure of quark matter remains mostly conjectural because it is difficult to perform calculations predicting the properties of quark matter. The reason is that QCD, the theory describing the dominant interaction between quarks, is strongly coupled at the densities and temperatures of greatest physical interest, and hence it is very hard to obtain any predictions from it. Here are brief descriptions of some of the standard approaches.

Lattice gauge theory

The only first-principles calculational tool currently available is lattice QCD, i.e. brute-force computer calculations. Because of a technical obstacle known as the fermion sign problem, this method can only be used at low density and high temperature (μ < T), and it predicts that the crossover to the quark–gluon plasma will occur around T = 150 MeV  However, it cannot be used to investigate the interesting color-superconducting phase structure at high density and low temperature.

Weak coupling theory

Because QCD is asymptotically free it becomes weakly coupled at unrealistically high densities, and diagrammatic methods can be used. Such methods show that the CFL phase occurs at very high density. At high temperatures, however, diagrammatic methods are still not under full control.

Models

To obtain a rough idea of what phases might occur, one can use a model that has some of the same properties as QCD, but is easier to manipulate. Many physicists use Nambu–Jona-Lasinio models, which contain no gluons, and replace the strong interaction with a four-fermion interaction. Mean-field methods are commonly used to analyse the phases. Another approach is the bag model, in which the effects of confinement are simulated by an additive energy density that penalizes unconfined quark matter.

Effective theories

Many physicists simply give up on a microscopic approach, and make informed guesses of the expected phases (perhaps based on NJL model results). For each phase, they then write down an effective theory for the low-energy excitations, in terms of a small number of parameters, and use it to make predictions that could allow those parameters to be fixed by experimental observations.

Other approaches

Main article: AdS/QCD

There are other methods that are sometimes used to shed light on QCD, but for various reasons have not yet yielded useful results in studying quark matter.

1/N expansion

Treat the number of colors N, which is actually 3, as a large number, and expand in powers of 1/N. It turns out that at high density the higher-order corrections are large, and the expansion gives misleading results.

Supersymmetry

Adding scalar quarks (squarks) and fermionic gluons (gluinos) to the theory makes it more tractable, but the thermodynamics of quark matter depends crucially on the fact that only fermions can carry quark number, and on the number of degrees of freedom in general.

Experimental challenges

Experimentally, it is hard to map the phase diagram of quark matter because it has been rather difficult to learn how to tune to high enough temperatures and density in the laboratory experiment using collisions of relativistic heavy ions as experimental tools. However, these collisions ultimately will provide information about the crossover from hadronic matter to QGP. It has been suggested that the observations of compact stars may also constrain the information about the high-density low-temperature region. Models of the cooling, spin-down, and precession of these stars offer information about the relevant properties of their interior. As observations become more precise, physicists hope to learn more.

One of the natural subjects for future research is the search for the exact location of the chiral critical point. Some ambitious lattice QCD calculations may have found evidence for it, and future calculations will clarify the situation. Heavy-ion collisions might be able to measure its position experimentally, but this will require scanning across a range of values of μ and T.

Evidence

In 2020, evidence was provided that the cores of neutron stars with mass ~2M_⊙ were likely composed of quark matter. Their result was based on neutron-star tidal deformability during a neutron star merger as measured by gravitational-wave observatories, leading to an estimate of star radius, combined with calculations of the equation of state relating the pressure and energy density of the star's core. The evidence was strongly suggestive but did not conclusively prove the existence of quark matter.

Eightfold way (physics)

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https://en.wikipedia.org/wiki/Eightfold_way_(physics) 

 

The meson octet. Particles along the same horizontal line share the same strangeness, s, while those on the same left-leaning diagonals share the same charge, q (given as multiples of the elementary charge).

In physics, the eightfold way is an organizational scheme for a class of subatomic particles known as hadrons that led to the development of the quark model. American physicist Murray Gell-Mann and Israeli physicist Yuval Ne'eman both proposed the idea in 1961. The name comes from Gell-Mann's (1961) paper and is an allusion to the Noble Eightfold Path of Buddhism.

Background

By 1947, physicists believed that they had a good understanding of what the smallest bits of matter were. There were electrons, protons, neutrons, and photons (the components that make up the vast part of everyday experience such as atoms and light) along with a handful of unstable (i.e., they undergo radioactive decay) exotic particles needed to explain cosmic rays observations such as pions, muons and hypothesized neutrino. In addition, the discovery of the positron suggested there could be anti-particles for each of them. It was known a "strong interaction" must exist to overcome electrostatic repulsion in atomic nuclei. Not all particles are influenced by this strong force but those that are, are dubbed "hadrons", which are now further classified as mesons (middle mass) and baryons (heavy weight).

But the discovery of the (neutral) kaon in late 1947 and the subsequent discovery of a positively charged kaon in 1949 extended the meson family in an unexpected way and in 1950 the lambda particle did the same thing for the baryon family. These particles decay much slower than they are produced, a hint that there are two different physical processes involved as suggested by Abraham Pais in 1952. Then in 1953, M. Gell Mann and a collaboration in Japan, Tadao Nakano and Kazuhiko Nishijima, independently suggested a new conserved value now known as "strangeness" during their attempts to understand the growing collection of known particles. The trend of discovering new mesons and baryons would continue through the 1950s as the number of known "elementary" particles ballooned. Physicists were interested in understanding hadron-hadron interactions via the strong interaction. The concept of isospin, introduced in 1932 by Werner Heisenberg shortly after the discovery of the neutron, was used to group some hadrons together into "multiplets" but no successful scientific theory as yet covered the hadrons as a whole. This was the beginning of a chaotic period in particle physics that has become known as the "particle zoo" era. The eightfold way ended up being an important big step towards the quark model solution.

Organization

Group representation theory is the mathematical underpinning behind the eightfold way but this rather technical mathematics is not needed to understand how it helps organize particles. Particles are sorted into groups as mesons or baryons. Within each group, they are further separated by their spin angular momentum. Symmetrical patterns appear when these groups of particles have their strangeness plotted against their electric charge. (This is the most common way to make these plots today but originally physicists used an equivalent pair of properties called hypercharge and isotopic spin, the latter of which is now known as isospin.) The symmetry in these patterns is a hint of the underlying symmetry of the strong interaction between the particles themselves. In the plots below, points representing particles that lie along the same horizontal line share the same strangeness, s, while those on the same left-leaning diagonals share the same electric charge, q (given as multiples of the elementary charge).

Mesons

In the original eightfold way, the mesons were organized into octets and singlets. This is one of the finer points of differences between the eightfold way and the quark model it inspired, which suggests the mesons should be grouped into nonets (groups of nine).

Meson octet

The pseudo-scalar meson octet.

The eightfold way organizes eight of the lowest spin-0 mesons into an octet. They are:

• 
  K⁰
  ,
  K⁺
  ,
  K⁻
  and
  K⁰
  kaons
• 
  π⁺
  ,
  π⁰
  , and
  π⁻
  pions
• 
  η
  

Diametrically opposite particles in the diagram are anti-particles of one-another while particles in the center are their own anti-particle.

Meson singlet

The chargeless, strangeless eta prime meson was originally classified by itself as a singlet:

• 
  η′
  

Under the quark model later developed, it is better viewed as part of a meson nonet, as previously mentioned.

Baryons

Baryon octet

The J = 1/ 2  baryon octet.

The eightfold way organizes the spin-1/ 2  baryons into an octet. They consist of

• neutron (n) and proton (p)
• 
  Σ⁻
  ,
  Σ⁰
  , and
  Σ⁺
  sigma baryons
• 
  Λ⁰
  , the strange lambda baryon
• 
  Ξ⁻
  and
  Ξ⁰
  xi baryons

Baryon decuplet

The J = 3/ 2  baryon decuplet.

The organizational principles of the eightfold way also apply to the spin-3/ 2  baryons, forming a decuplet.

• 
  Δ⁻
  ,
  Δ⁰
  ,
  Δ⁺
  , and
  Δ⁺⁺
  delta baryons
• 
  Σ^∗−
  ,
  Σ^∗0
  , and
  Σ^∗+
  sigma baryons
• 
  Ξ^∗−
  and
  Ξ^∗0
  xi baryons
• 
  Ω⁻
  omega baryon

However, one of the particles of this decuplet had never been previously observed when the eightfold way was proposed. Gell-Mann called this particle the
Ω⁻
and predicted in 1962 that it would have a strangeness −3, electric charge −1 and a mass near 1680 MeV/c². In 1964, a particle closely matching these predictions was discovered by a particle accelerator group at Brookhaven. Gell-Mann received the 1969 Nobel Prize in Physics for his work on the theory of elementary particles.

Historical development

Development

Historically, quarks were motivated by an understanding of flavour symmetry. First, it was noticed (1961) that groups of particles were related to each other in a way that matched the representation theory of SU(3). From that, it was inferred that there is an approximate symmetry of the universe which is parametrized by the group SU(3). Finally (1964), this led to the discovery of three light quarks (up, down, and strange) interchanged by these SU(3) transformations.

Modern interpretation

The eightfold way may be understood in modern terms as a consequence of flavor symmetries between various kinds of quarks. Since the strong nuclear force affects quarks the same way regardless of their flavor, replacing one flavor of quark with another in a hadron should not alter its mass very much, provided the respective quark masses are smaller than the strong interaction scale—which holds for the three light quarks. Mathematically, this replacement may be described by elements of the SU(3) group. The octets and other hadron arrangements are representations of this group.

Flavor symmetry

Main article: Flavour (particle physics)

SU(3)

There is an abstract three-dimensional vector space:

${\displaystyle \text{up quark}\to \left(\begin{array}{c}1\\ 0\\ 0\end{array}\right),\text{down quark}\to \left(\begin{array}{c}0\\ 1\\ 0\end{array}\right),\text{strange quark}\to \left(\begin{array}{c}0\\ 0\\ 1\end{array}\right)}$

and the laws of physics are approximately invariant under applying a determinant-1 unitary transformation to this space (sometimes called a flavour rotation):

${\displaystyle \left(\begin{array}{c}x\\ y\\ z\end{array}\right)\mapsto A\left(\begin{array}{c}x\\ y\\ z\end{array}\right),\text{where }A\text{ is in }SU(3)}$

Here, SU(3) refers to the Lie group of 3×3 unitary matrices with determinant 1 (special unitary group). For example, the flavour rotation

${\displaystyle A=\left(\begin{array}{ccc}0& 1& 0\\ -1& 0& 0\\ 0& 0& 1\end{array}\right)}$

is a transformation that simultaneously turns all the up quarks in the universe into down quarks and vice versa. More specifically, these flavour rotations are exact symmetries if only strong force interactions are looked at, but they are not truly exact symmetries of the universe because the three quarks have different masses and different electroweak interactions.

This approximate symmetry is called flavour symmetry, or more specifically flavour SU(3) symmetry.

See also: Clebsch–Gordan coefficients for SU(3) § Representations of the SU(3) group

Connection to representation theory

Main article: Particle physics and representation theory

See also: Compact group § Representation theory of a connected compact Lie group

 

Murray Gell-Mann (1929–2019) articulator and pioneer of group symmetry in QFT

Assume we have a certain particle—for example, a proton—in a quantum state ${\displaystyle |\psi ⟩}$. If we apply one of the flavour rotations A to our particle, it enters a new quantum state which we can call ${\displaystyle A|\psi ⟩}$. Depending on A, this new state might be a proton, or a neutron, or a superposition of a proton and a neutron, or various other possibilities. The set of all possible quantum states spans a vector space.

Representation theory is a mathematical theory that describes the situation where elements of a group (here, the flavour rotations A in the group SU(3)) are automorphisms of a vector space (here, the set of all possible quantum states that you get from flavour-rotating a proton). Therefore, by studying the representation theory of SU(3), we can learn the possibilities for what the vector space is and how it is affected by flavour symmetry.

Since the flavour rotations A are approximate, not exact, symmetries, each orthogonal state in the vector space corresponds to a different particle species. In the example above, when a proton is transformed by every possible flavour rotation A, it turns out that it moves around an 8 dimensional vector space. Those 8 dimensions correspond to the 8 particles in the so-called "baryon octet" (proton, neutron,
Σ⁺
,
Σ⁰
,
Σ⁻
,
Ξ⁻
,
Ξ⁰
,
Λ
). This corresponds to an 8-dimensional ("octet") representation of the group SU(3). Since A is an approximate symmetry, all the particles in this octet have similar mass.

Every Lie group has a corresponding Lie algebra, and each group representation of the Lie group can be mapped to a corresponding Lie algebra representation on the same vector space. The Lie algebra ${\displaystyle \mathfrak{s}\mathfrak{u}}$(3) can be written as the set of 3×3 traceless Hermitian matrices. Physicists generally discuss the representation theory of the Lie algebra ${\displaystyle \mathfrak{s}\mathfrak{u}}$(3) instead of the Lie group SU(3), since the former is simpler and the two are ultimately equivalent.

United Mine Workers of America

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/United_Mine_Workers_of_America 

 

UMWA

United Mine Workers of America
Founded	January 25, 1890 Columbus, Ohio, U.S.
Headquarters	Triangle, Virginia, U.S.
Location	United States, Canada
Members	80,000
Key people	Cecil Roberts, president
Affiliations	AFL–CIO, CLC
Website	www.umwa.org

The United Mine Workers of America (UMW or UMWA) is a North American labor union best known for representing coal miners. Today, the Union also represents health care workers, truck drivers, manufacturing workers and public employees in the United States and Canada. Although its main focus has always been on workers and their rights, the UMW of today also advocates for better roads, schools, and universal health care. By 2014, coal mining had largely shifted to open pit mines in Wyoming, and there were only 60,000 active coal miners. The UMW was left with 35,000 members, of whom 20,000 were coal miners, chiefly in underground mines in Kentucky and West Virginia. However it was responsible for pensions and medical benefits for 40,000 retired miners, and for 50,000 spouses and dependents.

The UMW was founded in Columbus, Ohio, on January 25, 1890, with the merger of two old labor groups, the Knights of Labor Trade Assembly No. 135 and the National Progressive Miners Union. Adopting the model of the American Federation of Labor (AFL), the union was initially established as a three-pronged labor tool: to develop mine safety; to improve mine workers' independence from the mine owners and the company store; and to provide miners with collective bargaining power.

After passage of the National Recovery Act in 1933 during the Great Depression, organizers spread throughout the United States to organize all coal miners into labor unions. Under the powerful leadership of John L. Lewis, the UMW broke with the American Federation of Labor and set up its own federation, the CIO (Congress of Industrial Organizations). Its organizers fanned out to organize major industries, including automobiles, steel, electrical equipment, rubber, paint and chemical, and fought a series of battles with the AFL. The UMW grew to 800,000 members and was an element in the New Deal Coalition supporting Democratic President Franklin D. Roosevelt. Lewis broke with Roosevelt in 1940 and left the CIO, leaving the UMW increasingly isolated in the labor movement. During World War II the UMW was involved in a series of major strikes and threatened walkouts that angered public opinion and energized pro-business opponents. After the war, the UMW concentrated on gaining large increases in wages, medical services and retirement benefits for its shrinking membership, which was contending with changes in technology and declining mines in the East.

Coal mining

Main articles: History of coal miners and History of coal mining in the United States

Development of the Union

The UMW was founded at Columbus City Hall in Columbus, Ohio, on January 25, 1890, by the merger of two earlier groups, the Knights of Labor Trade Assembly No. 135 and the National Progressive Miners Union. It was modeled after the American Federation of Labor (AFL). The Union's emergence in the 1890s was the culmination of decades of effort to organize mine workers and people in adjacent occupations into a single, effective negotiating unit. At the time coal was one of the most highly sought natural resources, as it was widely used to heat homes and to power machines in industries. The coal mines were a competitive and dangerous place to work. With the owners imposing reduced wages on a regular basis, in response to fluctuations in pricing, miners sought a group to stand up for their rights.

Early efforts

American Miners' Association

The first step in starting the union was the creation of the American Miners' Association. Scholars credit this organization with the beginning of the labor movement in the United States. The membership of the group grew rapidly. "Of an estimated 56,000 miners in 1865, John Hinchcliffe claimed 22,000 as members of the AMA. In response, the mine owners sought to stop the AMA from becoming more powerful. Members of the AMA were fired and blacklisted from employment at other mines. After a short time the AMA began to decline, and eventually ceased operations.

Workingman's Benevolent Association

Another early labor union that arose in 1868 was the Workingmen's Benevolent Association. This union was distinguished as a labor union for workers mining anthracite coal. The laborers formed the WBA to help improve pay and working conditions. The main reason for the success of this group was the president, John Siney, who sought a way both to increase miners benefits while also helping the operators earn a profit. They chose to limit the production of anthracite to keep its price profitable. Because the efforts of the WBA benefited the operators, they did not object when the union wanted to take action in the mines; they welcomed the actions that would secure their profit. Because the operators trusted the WBA, they agreed to the first written contract between miners and operators. As the union became more responsible in the operators' eyes, the union was given more freedoms. As a result, the health and spirits of the miners significantly improved.

The WBA could have been a very successful union had it not been for Franklin B. Gowen. In the 1870s Gowen owned the Reading Railroad, and bought several coal mines in the area. Because he owned the coal mines and controlled the means of transporting the coal, he was able to slowly destroy the labor union. He did everything in his power to produce the cheapest product and to ensure that non-union workers would benefit. As conditions for the miners of the WBA worsened, the union broke up and disappeared.

After the fall of the WBA, miners created many other small unions, including the Workingman's Protective Association (WPA) and the Miner's National Association (MNA). Although both groups had strong ideas and goals, they were unable to gain enough support and organization to succeed. The two unions did not last long, but provided greater support by the miners for a union which could withstand and help protect the workers' rights.

1870s

Although many labor unions were failing, two predominant unions arose that held promise to become strong and permanent advocates for the miners. The main problem during this time was the rivalry between the two groups. Because the National Trade Assembly #135, better known as the Knights of Labor, and the National Federation of Miners and Mine Laborers were so opposed to one another, they created problems for miners rather than solving key issues.

National Trade Assembly #135

The Great Seal of the Knights of Labor.

This union was more commonly known as the Knights of Labor and began around 1870 in the Philadelphia, Pennsylvania area. The main problem with the Knights of Labor was its secrecy. The members kept very private their affiliation and goals of the Knights of Labor. Because both miners and operators could become members, there was no commonality to unite the members. Also, the union did not see strikes as a means to attain rights. To many people of the time, a strike was the only way that they believed they would be heard.

The Knights of Labor tried to establish a strong and organized union, so they set up a system of local assemblies, or LAs. There were two main types of LAs, trade and mixed, with the trade LA being the most common. Although this system was put into place to create order, it did the opposite. Even though there were only two categories of LAs, there were many sub-divisions. For the most part it was impossible to tell how many trade and mixed LAs there were at a given time. Local assemblies began to arise and fall all around, and many members began to question whether or not the Knights of Labor was strong enough to fight for the most important issue of the time, achieving an eight-hour work day.

National Federation of Miners and Mine Laborers

This Union was formed by members of the Knights of Labor who realized that a secret and unified group would not turn into a successful union. The founders, John McBride, Chris Evans and Daniel McLaughlin, believed that creating an eight-hour work day would not only be beneficial for workers, but also as a means to stop overproduction, which would in turn help operators. The union was able to get cooperation from operators because they explained that the miners wanted better conditions because they felt as if they were part of the mining industry and also wanted the company to grow. But in order for the company to grow, the workers must have better conditions so that their labor could improve and benefit the operators.

The union's first priority was to get a fair weighing system within the mines. At a conference between the operators and the union, the idea of a new system of scaling was agreed upon, but the system was never implemented. Because the union did not deliver what it had promised, it lost support and members.

1880s

During this time, the rivalry between the two unions increased and eventually led to the formation of the UMW. The first of many arguments arose after the 1886 joint conference. The Knights of Labor did not want the NTA #135 to be in control, so they went against a lot of their decisions. Also, because the Knights of Labor were not in attendance at the conference, they were not able to vote against actions which they thought detrimental to gain rights for workers. The conference passed resolutions requiring the Knights of Labor to give up their secrecy and publicize material about its members and locations. The National Federation held another conference in 1887 attended by both groups. But it was unsuccessful in gaining agreement by the groups as to the next actions to take. In 1888, Samuel Gompers was elected as President of the National Federation of Miners, and George Harris first vice president.

Throughout 1887-1888 many joint conferences were held to help iron out the problems that the two groups were having. Many leaders of each groups began questioning the morals of the other union. One leader, William T. Lewis, thought there needed to be more unity within the union, and that competition for members between the two groups was not accomplishing anything. As a result of taking this position, he was replaced by John B. Rae as president of the NTA #135. This removal did not stop Lewis however; he got many people together who had been also thrown out of the Knights of Labor for trying to belong to both parties at once, along with the National Federation, and created the National Progressive Union of Miners and Mine Laborers (NPU).

Although the goal of the NPU in 1888 was ostensibly to create unity between the miners, it instead drew a stronger line distinguishing members of the NPU against those of the NTA #135. Because of the rivalry, miners of one labor union would not support the strikes of another, and many strikes failed. In December 1889, the president of the NPU set up a joint conference for all miners. John McBride, the president of NPU, suggested that the Knights of Labor should join the NPU to form a stronger union. John B. Rae reluctantly agreed and decided that the merged groups would meet on January 22, 1890.

Constitution of the Union: The Eleven Points

When the union was founded, the values of the UMWA were stated in the preamble:

We have founded the United Mine Workers of America for the purpose of ... educating all mine workers in America to realize the necessity of unity of action and purpose, in demanding and securing by lawful means the just fruits of our toil.

The UMWA constitution listed eleven points as the union's goals:

• Payment of a salary commensurate with the dangerous work conditions. This was one of the most important points of the constitution.
• Payment to be made fairly in legal tender, not with company scrip.
• Provide safe working conditions, with operators to use the latest technologies in order to preserve the lives and health of workers.
• Provide better ventilation systems to decrease black lung disease, and better drainage systems.
• Enforce safety laws and make it illegal for mines to have inadequate roof supports, or contaminated air and water in the mines.
• Limit regular hours to an eight-hour work day.
• End child labor, and strictly enforce the child labor law.
• Have accurate scales to weigh the coal products, so workers could be paid fairly. Many operators had altered scales that showed a lighter weight of coal than actually produced, resulting in underpayment to workers. Miners were paid per pound of coal that they produced.
• Payment should be made in legal tender.
• Establish unbiased public police forces in the mine areas that were not controlled by the operators. Many operators hired private police, who were used to harass the mine workers and impose company power. In company towns, the operators owned all the houses and controlled the police force; they could arbitrarily evict workers and arrest them unjustly.
• The workers reserved the right to strike, but would work with operators to reach reasonable conclusions to negotiations.

John L. Lewis

Main article: John Llewellyn Lewis

John L. Lewis (1880 – 1969) was the highly combative UMW president who thoroughly controlled the union from 1920 to 1960. A major player in the labor movement and national politics, in the 1930s he used UMW activists to organize new unions in autos, steel and rubber. He was the driving force behind the founding of the Congress of Industrial Organizations (CIO). It established the United Steel Workers of America and helped organize millions of other industrial workers in the 1930s.

After resigning as head of the CIO in 1941, he took the Mine Workers out of the CIO in 1942 and in 1944 took the union into the American Federation of Labor (AFL). Lewis was a Republican, but he played a major role in helping Franklin D. Roosevelt win re-election with a landslide in 1936, but as an isolationist supported by Communist elements in the CIO, Lewis broke with Roosevelt in 1940 on anti-Nazi foreign policy. (Following the 1939 German-Soviet pact of nonaggression, the Comintern had instructed communist parties in the West to oppose any support for nations at war with Nazi Germany.)

Lewis was a brutally effective and aggressive fighter and strike leader who gained high wages for his membership while steamrolling over his opponents, including the United States government. Lewis was one of the most controversial and innovative leaders in the history of labor, gaining credit for building the industrial unions of the CIO into a political and economic powerhouse to rival the AFL, yet was widely hated as he called nationwide coal strikes damaging the American economy in the middle of World War II. His massive leonine head, forest-like eyebrows, firmly set jaw, powerful voice, and ever-present scowl thrilled his supporters, angered his enemies, and delighted cartoonists. Coal miners for 40 years hailed him as the benevolent dictator who brought high wages, pensions and medical benefits, and damn the critics.

Achievements

• An eight-hour work day was gained in 1898. The first ideas of this demand were outlined in point six of the constitution.
• The union achieved collective bargaining rights in 1933.
• Health and retirement benefits for the miners and their families were earned in 1946.
• In 1969, the UMWA convinced the United States Congress to enact the landmark Federal Coal Mine Health and Safety Act, which provided compensation for miners suffering from Black Lung Disease.
• Relatively high wages for unionized miners by the early 1960s.

List of strikes

The union's history has numerous examples of strikes in which members and their supporters clashed with company-hired strikebreakers and government forces. The most notable include:

1890s

• Morewood massacre - April 3, 1891, in Morewood, Pennsylvania. A crowd of mostly immigrant strikers were fired on by deputized members of the 10th Regiment of the National Guard. At least ten strikers were killed and dozens injured.
• Bituminous Coal Miners' Strike of 1894 - April 21, 1894. This nationwide strike was called when the union was hardly four years old. Many of the workers salaries had been cut by 30% and with the demand for coal down during the recession, workers were desperate for work. The national guard was mobilized in several states to prevent or control violent clashes between strikers and strike breakers. The workers intended to strike for three weeks, hoping that this would produce a demand for coal and their wages would increase with its rising price. But, many union miners did not wish to cooperate with this plan and did not return to work at all. The union appeared weak. Other workers did not go out on strike, and with the demand low, they were able to produce sufficient coal. By being efficient in the mines, the operators saw no need to increase the wages of all the workers, and did not seem to care if the strike would end.

By June the demand for coal began to increase, and some operators decided to pay the workers their original salaries before the wage cut. However, not all demands across the country were met, and some workers continued to strike. The young union suffered damage in this uneven effort. The most important goal of the 1894 strike was not the restoration of wages, but rather the establishment of the UMWA as a cooperation at a national level.

• Lattimer Massacre - September 10, 1897. 19 miners were killed by police in Lattimer, Pennsylvania during a march in support of unions.
• Battle of Virden - October 1898. This was part of the larger mine wars that established Illinois as the leading union state in the country, and a reason that Mary Harris "Mother" Jones is buried at Mount Olive, Illinois.

Early 1900s

Coal miners in Hazleton, Pennsylvania in 1905

• The five-month Coal Strike of 1902, led by the United Mine Workers and centered in eastern Pennsylvania, ended after direct intervention of President Theodore Roosevelt as a neutral arbitrator.
• 1903 Colorado coal strike - October 1903. The United Mine Workers conducted a strike in Colorado, called in October 1903 by President Mitchell, and lasting into 1904. The strike, while overshadowed by a simultaneous strike conducted by the Western Federation of Miners among hard rock miners in the Cripple Creek District, contributed to the labor struggles in Colorado. These came to be known as the Colorado Labor Wars. During the United Mine Workers effort, operators directed their private forces to attack and beat traveling union officers and organizers, which ultimately helped to break the strike. These beatings were a mystery until publication of The Pinkerton Labor Spy (1907) by Morris Friedman, which revealed that the UMWA had been infiltrated by labor spies from the Pinkerton agency.
• 1908 Alabama coal strike - June–August 1908. Notable because the 18,000 UMWA-organized strikers, more than half of those working in the Birmingham District, were racially integrated. That fact helped galvanize political opposition to the strikers in the segregated state. The governor used the Alabama State Militia to end the work stoppage. The union adopted racial segregation of workers in Alabama in order to reduce the political threat to the organization.
• Westmoreland County Coal Strike - 1910-1911, a 16-month coal strike in Pennsylvania led largely by Slovak immigrant miners, this strike involved 15,000 coal miners. Sixteen people were killed during the strike, nearly all of them striking miners or members of their families.
• Colorado Coalfield War - September 1913–December 1914. A frequently violent strike against the John D. Rockefeller, Jr.-Colorado Fuel and Iron company. Many strikers and opposition were killed before the violent reached a peak following the 20 April 1914 Ludlow Massacre. An estimated 20 people, including women and children, were killed by armed police, hired guns, and Colorado National Guardsmen who broke up a tent colony formed by families of miners who had been evicted from company-owned housing. The strike was partially led by John R. Lawson, a UMWA organizer and saw the participation of famed activist Mother Jones. The UMWA purchased part of Ludlow site and constructed the Ludlow Monument in commemoration of those who died.
• Hartford coal mine riot - July 1914. The surface plant of the Prairie Creek coal mine was destroyed, and two non-union miners murdered by union miners and sympathizers. The mine owners sued the local and national organizations of the United Mine Workers Union. The national UMWA was found not complicit, but the local was judged culpable of encouraging the rioters, and made to pay US$2.1 million.

"KEEPING WARM"
Los Angeles Times
November 22, 1919

• United Mine Workers coal strike of 1919 - November 1, 1919. Some 400,000 members of the United Mine Workers went on strike on November 1, 1919, although Attorney General A. Mitchell Palmer had invoked the Lever Act, a wartime measure criminalizing interference with the production or transportation of necessities, and obtained an injunction against the strike on October 31. The coal operators smeared the strikers with charges that Russian communist leaders Lenin and Trotsky had ordered the strike and were financing it, and some of the press repeated those claims.
• Matewan, West Virginia - May 19, 1920. 12 men were killed in a gunfight between town residents and the Baldwin–Felts Detective Agency, hired by mine owners. Director John Sayles directed a feature film, Matewan, based on these events.
• The 'Redneck War' - 1920-21. Generally viewed as beginning with the Matewan Massacre, this conflict involved the struggle to unionize the southwestern area of West Virginia. It led to the march of 10,000 armed miners on the county seat at Logan. In the Battle of Blair Mountain, miners fought state militia, local police, and mine guards. These events are depicted in the novels Storming Heaven (1987) by Denise Giardina and Blair Mountain (2005) by Jonathan Lynn.
• 1920 Alabama coal strike, a lengthy, violent, expensive and fruitless attempt to achieve union recognition in the coal mines around Birmingham left 16 men dead; one black man was lynched.
• Herrin massacre occurred in June 1922 in Herrin, Illinois. 19 strikebreakers and 2 union miners were killed in mob action between June 21–22, 1922.

1922-1925 Nova Scotia strikes

WPA poster

In the 1920s, about 12,000 Nova Scotia miners were represented by the UMWA. These workers lived in very difficult economic circumstances in company towns. The Dominion Steel and Coal Corporation, also known as the British Empire Steel Corporation, or BESCO, controlled most coal mines and every steel mill in the province. BESCO was in financial difficulties and repeatedly attempted to reduce wages and bust the union.

Led by J. B. McLachlan, miners struck in 1923, and were met by locally and provincially-deployed troops. This would eventually lead to the federal government introducing legislation limiting the civil use of troops.

In 1925 BESCO announced that it would not longer give credit at their company stores and that wages would be cut by 20%. The miners responded with a strike. This led to violence with company police firing on strikers, killing miner William Davis, as well as the looting and arson of company property.

This crisis led to the Nova Scotia government acting in 1937 to improve the rights of all wage earners, and these reforms served as a model across Canada, at both provincial and federal levels.

The Brookside Strike

In the summer of 1973, workers at the Duke Power-owned Eastover Mining Company's Brookside Mine and Prep Plant in Harlan County, Kentucky, voted to join the union. Eastover management refused to sign the contract and the miners went on strike. Duke Power attempted to bring in replacement non-union workers or "scabs" but many were blocked from entering the mine by striking workers and their families on the picket line. Local judge F. Byrd Hogg was a coal operator himself and consistently ruled for Eastover. During much of the strike the mine workers' wives and children joined the picket lines. Many were arrested, some hit by baseball bats, shot at, and struck by cars. One striking miner, Lawrence Jones, was shot and killed by a Strikebreaker.

Three months after returning to work, the national UMWA contract expired. On November 12, 1974, 120,000 miners nationwide walked off the job. The nationwide strike was bloodless and a tentative contract was achieved three weeks later. This opened the mines and reactivated the railroad haulers in time for Christmas. These events are depicted in the documentary film Harlan County, USA.

The Pittston strike

The Pittston Coal strike of 1989-1990 began as a result of a withdrawal of the Pittston Coal Group also known as the Pittston Company from the Bituminous Coal Operators Association (BCOA) and a refusal of the Pittston Coal group to pay the health insurance payments for miners who were already retired. The owner of the Pittston company at the time, Paul Douglas, left the BCOA because he wanted to be able to produce coal seven days a week and did not want his company to pay the fee for the insurance.

The Pittson company was seen as having inadequate safety standards after the Buffalo Creek flood of 1972 in which 125 miners were killed. The company also was very financially unstable and in debt. The mines associated with the company were located mostly in Virginia, with mines also in West Virginia and Kentucky.

On 31 January 1988 Douglas cut off retirement and health care funds to about 1500 retired miners, widows of miners, and disabled miners. To avoid a strike, Douglas threatened that if a strike were to take place, that the miners would be replaced by other workers. The UMW called this action unjust and took the Pittston company to court.

Miners worked from January 1988 to April 1989 without a contract. Tension in the company grew and on 5 April 1989 the workers declared a strike. Many months of both violent and nonviolent strike actions took place. On 20 February 1990 a settlement was finally reached between the UMWA and the Pittston Coal Company.

Internal conflict

The union's history has sometimes been marked by internal strife and corruption, including the 1969 murder of Joseph Yablonski, a reform candidate who lost a race for union president against incumbent W. A. Boyle, along with his wife and 25-year-old daughter. Boyle was later convicted of ordering these murders.

The killing of Yablonski resulted in the birth of a pro-democracy movement called the "Miners for Democracy" (MFD) which swept Boyle and his regime out of office, and replaced them with a group of leaders who had been most recently rank and file miners.

Led by new president Arnold Miller, the new leadership enacted a series of reforms which gave UMWA members the right to elect their leaders at all levels of the union and to ratify the contracts under which they worked.

Decline of labor unionism in mining

Decreased faith in the UMW to support the rights of the miners caused many to leave the union. Coal demand was curbed by competition from other energy sources. The main cause of the decline in the union during the 1920s and 1930s was the introduction of more efficient and easily produced machines into the coal mines. In previous years, less than 41% of coal was cut by the machines. However, by 1930, 81% was being cut by the machines and now there were machines that could also surface mine and load the coal into the trucks. With more machines that could do the same labor, unemployment in the mines grew and wages were cut back. As the problems grew, many people did not believe that the UMW could ever become as powerful as it was before the start of the war. The decline in the union began in the 1920s and continued through the 1930s. Slowly the membership of the UMWA grew back up in numbers, with the majority in District 50, a catch-all district for workers in fields related to coal mining, such as the chemical and energy industries. This district gained organizational independence in 1961, and then fell into dispute with the remainder of the union, leading in 1968 to its expulsion.

In the 1970s and after

Diana Baldwin and Anita Cherry are believed to have been the first women to work inside an American coal mine, and were the first women to work inside a mine who were members of the UMW. They began that work in 1973 in Jenkins. However, a general decline in union effectiveness characterized the 1970s and 1980s, leading to new kinds of activism, particularly in the late 1970s. Workers saw their unions back down in the face of aggressive management.

Other factors contributed to the decline in unionism generally and UMW specifically. The coal industry was not prepared economically to deal with such a drop in demand for coal. Demand for coal was very high during World War II, but decreased dramatically after the war, in part due to competition from other energy sources. In efforts to improve air quality, municipal governments started to ban the use of coal as household fuel. The end of wartime price controls introduced competition to produce cheaper coal, putting pressure on wages.

These problems—perceived weakness of the unions, loss of control over jobs, drop in demand, and competition—decreased the faith of miners in their union. By 1998 the UMW had about 240,000 members, half the number that it had in 1946. As of the early 2000s, the union represents about 42 percent of all employed miners.

Affiliation with other unions

At some point before 1930, the UMW became a member of the American Federation of Labor. The UMW leadership was part of the driving force to change the way workers were organized, and the UMW was one of the charter members when the new Congress of Industrial Organizations was formed in 1935. However, the AFL leadership did not agree with the philosophy of industrial unionization, and the UMW and nine other unions that had formed the CIO were kicked out of the AFL in 1937.

In 1942, the UMW chose to leave the CIO, and, for the next five years, were an independent union. In 1947, the UMW once again joined the AFL, but the remarriage was a short one, as the UMW was forced out of the AFL in 1948, and at that point, became the largest non-affiliated union in the United States.

In 1982, Richard Trumka was elected the leader of the UMW. Trumka spent the 1980s healing the rift between the UMW and the now-conjoined AFL–CIO (which was created in 1955 with the merger of the AFL and the CIO). In 1989, the UMW was again taken into the fold of the large union umbrella.

Political involvement

United Mine Workers meeting with Congressmember Tom O'Halleran in 2020.

Throughout the years, the UMW has taken political stands and supported candidates to help achieve union goals.

The United Mine Workers ran candidate Frank Henry Sherman under the union banner in the 1905 Alberta general election. Sherman's candidacy was driven to appeal to the significant population of miners working in the camps of southern Alberta. He finished second in the riding of Pincher Creek.

The biggest conflict between the UMW and the government was while Franklin Roosevelt was president of the United States and John L. Lewis was president of the UMW. Originally, the two worked together well, but, after the 1937 strike of United Automobile Workers against General Motors, Lewis stopped trusting Roosevelt, claiming that Roosevelt had gone back on his word. This conflict led Lewis to resign as CIO president. Roosevelt repeatedly won large majorities of the union votes, even in 1940 when Lewis took an isolationist position on Europe, as demanded by far-left union elements. Lewis denounced Roosevelt as a power-hungry war monger, and endorsed Republican Wendell Willkie.

The tension between the two leaders escalated during World War II. Roosevelt in 1943 was outraged when Lewis threatened a major strike to end anthracite coal production needed by the war effort. He threatened government intervention and Lewis retreated.

The UMW represents West Virginia coal miners and endorsed Joe Manchin (D-W.Va.) in the 2018 United States Senate election in West Virginia. In 2021 the union urged him to revisit his opposition to President Biden's Build Back Better Plan, noting that the bill includes an extension of a fund that provides benefits to coal miners suffering from black lung disease, which expires at the end of the year. The UMWA also touted tax incentives that encourage manufacturers to build facilities in coalfields that would employ thousands of miners who lost their jobs.

"For those and other reasons, we are disappointed that the bill will not pass," Cecil Roberts, the union's president said. "We urge Senator Manchin to revisit his opposition to this legislation and work with his colleagues to pass something that will help keep coal miners working, and have a meaningful impact on our members, their families, and their communities."

Recent elections

In 2008 the UMWA supported Barack Obama as the best candidate to help achieve more rights for the mine workers.

In 2012, the UMWA National COMPAC Council did not make an endorsement in the election for President of the United States, citing "Neither candidate has yet demonstrated that he will be on the side of UMWA members and their families as president."

In 2014, the UMWA endorsed Kentucky Democrat Alison Lundergan Grimes for U.S. Senate.

List of presidents

• John B. Rae – 1890–1892 (founding president)
• John McBride – 1892–1895
• Phil Penna – 1895–1896
• Michael Ratchford – 1897–1898
• John Mitchell – 1898–1907
• Thomas Lewis – 1908–1910
• John White – 1911–1917
• Frank Hayes – 1917–1920
• John L. Lewis – 1920–1960
• Thomas Kennedy – 1960–1963
• W. A. "Tony" Boyle – 1963–1972
• Arnold Miller – 1972–1979
• Sam Church – 1979–1982
• Richard Trumka – 1982–1995
• Cecil Roberts – 1995–present