Matter

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Matter

Matter is usually classified into three classical states, with plasma sometimes added as a fourth state. From top to bottom: quartz (solid), water (liquid), nitrogen dioxide (gas), and a plasma globe (plasma).

In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles (or combination of particles) that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light. Matter exists in various states (also known as phases). These include classical everyday phases such as solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam – but other states are possible, including plasma, Bose–Einstein condensates, fermionic condensates, and quark–gluon plasma.

Usually atoms can be imagined as a nucleus of protons and neutrons, and a surrounding "cloud" of orbiting electrons which "take up space". However this is only somewhat correct, because subatomic particles and their properties are governed by their quantum nature, which means they do not act as everyday objects appear to act – they can act like waves as well as particles and they do not have well-defined sizes or positions. In the Standard Model of particle physics, matter is not a fundamental concept because the elementary constituents of atoms are quantum entities which do not have an inherent "size" or "volume" in any everyday sense of the word. Due to the exclusion principle and other fundamental interactions, some "point particles" known as fermions (quarks, leptons), and many composites and atoms, are effectively forced to keep a distance from other particles under everyday conditions; this creates the property of matter which appears to us as matter taking up space.

For much of the history of the natural sciences people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter, independently appeared in ancient Greece and ancient India among Buddhists, Hindus and Jains in 1st-millennium BC. Ancient philosophers who proposed the particulate theory of matter include Kanada (c. 6th–century BC or after), Leucippus (~490 BC) and Democritus (~470–380 BC).^[8]

Comparison with mass

Matter should not be confused with mass, as the two are not the same in modern physics. Matter is a general term describing any 'physical substance'. By contrast, mass is not a substance but rather a quantitative property of matter and other substances or systems; various types of mass are defined within physics – including but not limited to rest mass, inertial mass, relativistic mass, mass–energy.

While there are different views on what should be considered matter, the mass of a substance has exact scientific definitions. Another difference is that matter has an "opposite" called antimatter, but mass has no opposite—there is no such thing as "anti-mass" or negative mass, so far as is known, although scientists do discuss the concept. Antimatter has the same (i.e. positive) mass property as its normal matter counterpart.

Different fields of science use the term matter in different, and sometimes incompatible, ways. Some of these ways are based on loose historical meanings, from a time when there was no reason to distinguish mass from simply a quantity of matter. As such, there is no single universally agreed scientific meaning of the word "matter". Scientifically, the term "mass" is well-defined, but "matter" can be defined in several ways. Sometimes in the field of physics "matter" is simply equated with particles that exhibit rest mass (i.e., that cannot travel at the speed of light), such as quarks and leptons. However, in both physics and chemistry, matter exhibits both wave-like and particle-like properties, the so-called wave–particle duality.

Definition

Based on atoms

A definition of "matter" based on its physical and chemical structure is: matter is made up of atoms. Such atomic matter is also sometimes termed ordinary matter. As an example, deoxyribonucleic acid molecules (DNA) are matter under this definition because they are made of atoms. This definition can be extended to include charged atoms and molecules, so as to include plasmas (gases of ions) and electrolytes (ionic solutions), which are not obviously included in the atoms definition. Alternatively, one can adopt the protons, neutrons, and electrons definition.

Based on protons, neutrons and electrons

A definition of "matter" more fine-scale than the atoms and molecules definition is: matter is made up of what atoms and molecules are made of, meaning anything made of positively charged protons, neutral neutrons, and negatively charged electrons. This definition goes beyond atoms and molecules, however, to include substances made from these building blocks that are not simply atoms or molecules, for example electron beams in an old cathode ray tube television, or white dwarf matter—typically, carbon and oxygen nuclei in a sea of degenerate electrons. At a microscopic level, the constituent "particles" of matter such as protons, neutrons, and electrons obey the laws of quantum mechanics and exhibit wave–particle duality. At an even deeper level, protons and neutrons are made up of quarks and the force fields (gluons) that bind them together, leading to the next definition.

Based on quarks and leptons

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

As seen in the above discussion, many early definitions of what can be called "ordinary matter" were based upon its structure or "building blocks". On the scale of elementary particles, a definition that follows this tradition can be stated as: "ordinary matter is everything that is composed of quarks and leptons", or "ordinary matter is everything that is composed of any elementary fermions except antiquarks and antileptons". The connection between these formulations follows.

Leptons (the most famous being the electron), and quarks (of which baryons, such as protons and neutrons, are made) combine to form atoms, which in turn form molecules. Because atoms and molecules are said to be matter, it is natural to phrase the definition as: "ordinary matter is anything that is made of the same things that atoms and molecules are made of". (However, notice that one also can make from these building blocks matter that is not atoms or molecules.) Then, because electrons are leptons, and protons, and neutrons are made of quarks, this definition in turn leads to the definition of matter as being "quarks and leptons", which are two of the four types of elementary fermions (the other two being antiquarks and antileptons, which can be considered antimatter as described later). Carithers and Grannis state: "Ordinary matter is composed entirely of first-generation particles, namely the [up] and [down] quarks, plus the electron and its neutrino." (Higher generations particles quickly decay into first-generation particles, and thus are not commonly encountered.)

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. The W and Z bosons that mediate the weak force are not made of quarks or leptons, and so are not ordinary matter, even if they have mass. In other words, mass is not something that is exclusive to ordinary matter.

The quark–lepton definition of ordinary matter, however, identifies not only 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. In other words, most of what composes the "mass" of ordinary matter is due to the binding energy of quarks within protons and neutrons. For example, the sum of the mass of the three quarks in a nucleon is approximately 12.5 MeV/c², which is low compared to the mass of a nucleon (approximately 938 MeV/c²).  The bottom line is that most of the mass of everyday objects comes from the interaction energy of its elementary components.

The Standard Model groups matter particles into three generations, where each generation consists of two quarks and two leptons. The first generation is the up and down quarks, the electron and the electron neutrino; the second includes the charm and strange quarks, the muon and the muon neutrino; the third generation consists of the top and bottom quarks and the tau and tau neutrino. The most natural explanation for this would be that quarks and leptons of higher generations are excited states of the first generations. If this turns out to be the case, it would imply that quarks and leptons are composite particles, rather than elementary particles.

This quark–lepton definition of matter also leads to what can be described as "conservation of (net) matter" laws—discussed later below. Alternatively, one could return to the mass–volume–space concept of matter, leading to the next definition, in which antimatter becomes included as a subclass of matter.

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

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

The observation that matter occupies space goes back to antiquity. However, an explanation for why matter occupies space is recent, and is argued to be a result of the phenomenon described in the Pauli exclusion principle, which applies to fermions. Two particular examples where the exclusion principle clearly relates matter to the occupation of space are white dwarf stars and neutron stars, discussed further below.

Thus, matter can be defined as everything composed of elementary fermions. Although we don't encounter them in everyday life, antiquarks (such as the antiproton) and antileptons (such as the positron) are the antiparticles of the quark and the lepton, are elementary fermions as well, and have essentially the same properties as quarks and leptons, including the applicability of the Pauli exclusion principle which can be said to prevent two particles from being in the same place at the same time (in the same state), i.e. makes each particle "take up space". This particular definition leads to matter being defined to include anything made of these antimatter particles as well as the ordinary quark and lepton, and thus also anything made of mesons, which are unstable particles made up of a quark and an antiquark.

In general relativity and cosmology

In the context of relativity, mass is not an additive quantity, in the sense that one can not add the rest masses of particles in a system to get the total rest mass of the system. Thus, in relativity usually a more general view is that it is not the sum of rest masses, but the energy–momentum tensor that quantifies the amount of matter. This tensor gives the rest mass for the entire system. "Matter" therefore is sometimes considered as anything that contributes to the energy–momentum of a system, that is, anything that is not purely gravity. This view is commonly held in fields that deal with general relativity such as cosmology. In this view, light and other massless particles and fields are all part of "matter".

Structure

In particle physics, fermions are particles that obey Fermi–Dirac statistics. Fermions can be elementary, like the electron—or composite, like the proton and neutron. In the Standard Model, there are two types of elementary fermions: quarks and leptons, which are discussed next.

Quarks

Main article: Quark

Quarks are massive particles of spin-1⁄2, implying that they are fermions. They carry an electric charge of −1⁄3 e (down-type quarks) or +2⁄3 e (up-type quarks). For comparison, an electron has a charge of −1 e. They also carry colour charge, which is the equivalent of the electric charge for the strong interaction. Quarks also undergo radioactive decay, meaning that they are subject to the weak interaction.

Quark properties

name	symbol	spin	electric charge (e)	mass (MeV/c2)	mass comparable to	antiparticle	antiparticle symbol
up-type quarks
up	u	1⁄2	+2⁄3	1.5 to 3.3	~ 5 electrons	antiup	u
charm	c	1⁄2	+2⁄3	1160 to 1340	~1 proton	anticharm	c
top	t	1⁄2	+2⁄3	169,100 to 173,300	~180 protons or ~1 tungsten atom	antitop	t
down-type quarks
down	d	1⁄2	−1⁄3	3.5 to 6.0	~10 electrons	antidown	d
strange	s	1⁄2	−1⁄3	70 to 130	~ 200 electrons	antistrange	s
bottom	b	1⁄2	−1⁄3	4130 to 4370	~ 5 protons	antibottom	b

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

Baryonic

Main article: Baryon

Baryons are strongly interacting fermions, and so are subject to Fermi–Dirac statistics. Amongst the baryons are the protons and neutrons, which occur in atomic nuclei, but many other unstable baryons exist as well. The term baryon usually refers to triquarks—particles made of three quarks. Also, "exotic" baryons made of four quarks and one antiquark are known as pentaquarks, but their existence is not generally accepted.

Baryonic matter is the part of the universe that is made of baryons (including all atoms). This part of the universe does not include dark energy, dark matter, black holes or various forms of degenerate matter, such as compose white dwarf stars and neutron stars. Microwave light seen by Wilkinson Microwave Anisotropy Probe (WMAP), suggests that only about 4.6% of that part of the universe within range of the best telescopes (that is, matter that may be visible because light could reach us from it), is made of baryonic matter. About 26.8% is dark matter, and about 68.3% is dark energy.

The great majority of ordinary matter in the universe is unseen, since visible stars and gas inside galaxies and clusters account for less than 10 per cent of the ordinary matter contribution to the mass–energy density of the universe.

A comparison between the white dwarf IK Pegasi B (center), its A-class companion IK Pegasi A (left) and the Sun (right). This white dwarf has a surface temperature of 35,500 K.

Hadronic

Hadronic matter can refer to 'ordinary' baryonic matter, made from hadrons (baryons and mesons), or quark matter (a generalisation of atomic nuclei), i.e. the 'low' temperature QCD matter. It includes degenerate matter and the result of high energy heavy nuclei collisions.

Degenerate

Main article: Degenerate matter

In physics, degenerate matter refers to the ground state of a gas of fermions at a temperature near absolute zero. The Pauli exclusion principle requires that only two fermions can occupy a quantum state, one spin-up and the other spin-down. Hence, at zero temperature, the fermions fill up sufficient levels to accommodate all the available fermions—and in the case of many fermions, the maximum kinetic energy (called the Fermi energy) and the pressure of the gas becomes very large, and depends on the number of fermions rather than the temperature, unlike normal states of matter.

Degenerate matter is thought to occur during the evolution of heavy stars. The demonstration by Subrahmanyan Chandrasekhar that white dwarf stars have a maximum allowed mass because of the exclusion principle caused a revolution in the theory of star evolution.

Degenerate matter includes the part of the universe that is made up of neutron stars and white dwarfs.

Strange

Main article: 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 contrasted with nuclear matter, which is a liquid of neutrons and protons (which themselves are built out of up and down quarks), and with non-strange quark matter, which is a quark liquid that contains only up and down quarks. At high enough density, strange matter is expected to be color superconducting. Strange matter is hypothesized to occur in the core of neutron stars, or, more speculatively, as isolated droplets that may vary in size from femtometers (strangelets) to kilometers (quark stars).

Two meanings

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

1. The broader meaning is just quark matter that contains three flavors of quarks: up, down, and strange. In this definition, there is a critical pressure and an associated critical density, and when nuclear matter (made of protons and neutrons) is compressed beyond this density, the protons and neutrons dissociate into quarks, yielding quark matter (probably strange matter).
2. The narrower meaning is quark matter that is more stable than nuclear matter. The idea that this could happen is the "strange matter hypothesis" of Bodmer and Witten. 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

Main article: Lepton

Leptons are particles of spin-1⁄2, meaning that they are fermions. They carry an electric charge of −1 e (charged leptons) or 0 e (neutrinos). Unlike quarks, leptons do not carry colour charge, meaning that they do not experience the strong interaction. Leptons also undergo radioactive decay, meaning that they are subject to the weak interaction. Leptons are massive particles, therefore are subject to gravity.

Lepton properties

name	symbol	spin	electric charge (e)	mass (MeV/c2)	mass comparable to	antiparticle	antiparticle symbol
charged leptons
electron	e−	1⁄2	−1	0.5110	1 electron	antielectron	e+
muon	μ−	1⁄2	−1	105.7	~ 200 electrons	antimuon	μ+
tau	τ−	1⁄2	−1	1,777	~ 2 protons	antitau	τ+
neutrinos
electron neutrino	ν e	1⁄2	0	< 0.000460	< 1⁄1000 electron	electron antineutrino	ν e
muon neutrino	ν μ	1⁄2	0	< 0.19	< 1⁄2 electron	muon antineutrino	ν μ
tau neutrino	ν τ	1⁄2	0	< 18.2	< 40 electrons	tau antineutrino	ν τ

Phases

Main article: Phase (matter)

See also: Phase diagram and State of matter

 

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.

In bulk, matter can exist in several different forms, or states of aggregation, known as phases, depending on ambient pressure, temperature and volume. A phase is a form of matter that has a relatively uniform chemical composition and physical properties (such as density, specific heat, refractive index, and so forth). These phases include 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).

Antimatter

Main article: Antimatter

 

Unsolved problem in physics:

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

(more unsolved problems in physics)

Antimatter is matter that is composed of the antiparticles of those that constitute ordinary matter. If a particle and its antiparticle come into contact with each other, the two annihilate; that is, they may both be converted into other particles with equal energy in accordance with Albert Einstein's equation E = mc². These new particles may be high-energy photons (gamma rays) or other particle–antiparticle pairs. The resulting particles are endowed with an amount of kinetic energy equal to the difference between the rest mass of the products of the annihilation and the rest mass of the original particle–antiparticle pair, which is often quite large. Depending on which definition of "matter" is adopted, antimatter can be said to be a particular subclass of matter, or the opposite of matter.

Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities (as the result of radioactive decay, lightning or cosmic rays). This is because antimatter that came to exist on Earth outside the confines of a suitable physics laboratory would almost instantly meet the ordinary matter that Earth is made of, and be annihilated. Antiparticles and some stable antimatter (such as antihydrogen) can be made in tiny amounts, but not in enough quantity to do more than test a few of its theoretical properties.

There is considerable speculation both in science and science fiction as to why the observable universe is apparently almost entirely matter (in the sense of quarks and leptons but not antiquarks or antileptons), and whether other places are almost entirely antimatter (antiquarks and antileptons) instead. In the early universe, it is thought that matter and antimatter were equally represented, and the disappearance of antimatter requires an asymmetry in physical laws called CP (charge-parity) symmetry violation, which can be obtained from the Standard Model, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics. Possible processes by which it came about are explored in more detail under baryogenesis.

Formally, antimatter particles can be defined by their negative baryon number or lepton number, while "normal" (non-antimatter) matter particles have positive baryon or lepton number. These two classes of particles are the antiparticle partners of one another.

In October 2017, scientists reported further evidence that matter and antimatter, equally produced at the Big Bang, are identical, should completely annihilate each other and, as a result, the universe should not exist. This implies that there must be something, as yet unknown to scientists, that either stopped the complete mutual destruction of matter and antimatter in the early forming universe, or that gave rise to an imbalance between the two forms.

Conservation

Two quantities that can define an amount of matter in the quark–lepton sense (and antimatter in an antiquark–antilepton sense), baryon number and lepton number, are conserved in the Standard Model. A baryon such as the proton or neutron has a baryon number of one, and a quark, because there are three in a baryon, is given a baryon number of 1/3. So the net amount of matter, as measured by the number of quarks (minus the number of antiquarks, which each have a baryon number of −1/3), which is proportional to baryon number, and number of leptons (minus antileptons), which is called the lepton number, is practically impossible to change in any process. Even in a nuclear bomb, none of the baryons (protons and neutrons of which the atomic nuclei are composed) are destroyed—there are as many baryons after as before the reaction, so none of these matter particles are actually destroyed and none are even converted to non-matter particles (like photons of light or radiation). Instead, nuclear (and perhaps chromodynamic) binding energy is released, as these baryons become bound into mid-size nuclei having less energy (and, equivalently, less mass) per nucleon compared to the original small (hydrogen) and large (plutonium etc.) nuclei. Even in electron–positron annihilation, there is no net matter being destroyed, because there was zero net matter (zero total lepton number and baryon number) to begin with before the annihilation—one lepton minus one antilepton equals zero net lepton number—and this net amount matter does not change as it simply remains zero after the annihilation.

In short, matter, as defined in physics, refers to baryons and leptons. The amount of matter is defined in terms of baryon and lepton number. Baryons and leptons can be created, but their creation is accompanied by antibaryons or antileptons; and they can be destroyed, by annihilating them with antibaryons or antileptons. Since antibaryons/antileptons have negative baryon/lepton numbers, the overall baryon/lepton numbers aren't changed, so matter is conserved. However, baryons/leptons and antibaryons/antileptons all have positive mass, so the total amount of mass is not conserved. Further, outside of natural or artificial nuclear reactions, there is almost no antimatter generally available in the universe (see baryon asymmetry and leptogenesis), so particle annihilation is rare in normal circumstances.

Dark

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 and 73% is dark energy.

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

 

Main articles: Dark matter, Lambda-CDM model, and WIMPs

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

Energy

Main article: Dark energy

See also: Big Bang § Dark energy

In cosmology, dark energy is the name given to the source of the repelling influence that is accelerating the rate of expansion of the universe. Its precise nature is currently a mystery, although its effects can reasonably be modeled by assigning matter-like properties such as energy density and pressure to the vacuum itself.

Fully 70% of the matter density in the universe appears to be in the form of dark energy. Twenty-six percent is dark matter. Only 4% is ordinary matter. So less than 1 part in 20 is made out of matter we have observed experimentally or described in the standard model of particle physics. Of the other 96%, apart from the properties just mentioned, we know absolutely nothing.

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

Exotic

Main article: Exotic matter

Exotic matter is a concept of particle physics, which may include dark matter and dark energy but goes further to include any hypothetical material that violates one or more of the properties of known forms of matter. Some such materials might possess hypothetical properties like negative mass.

Historical study

Antiquity (c. 600 BC–c. 322 BC)

In ancient India, the Buddhists, the Hindus and the Jains each developed a particulate theory of matter, positing that all matter is made of atoms (paramanu, pudgala) that are in itself "eternal, indestructible and innumerable" and which associate and dissociate according to certain fundamental natural laws to form more complex matter or change over time. They coupled their ideas of soul, or lack thereof, into their theory of matter. The strongest developers and defenders of this theory were the Nyaya-Vaisheshika school, with the ideas of the philosopher Kanada (c. 6th–century BC) being the most followed. The Buddhists also developed these ideas in late 1st-millennium BCE, ideas that were similar to the Vaishashika Hindu school, but one that did not include any soul or conscience. The Jains included soul (jiva), adding qualities such as taste, smell, touch and color to each atom. They extended the ideas found in early literature of the Hindus and Buddhists by adding that atoms are either humid or dry, and this quality cements matter. They also proposed the possibility that atoms combine because of the attraction of opposites, and the soul attaches to these atoms, transforms with karma residue and transmigrates with each rebirth.

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

Aristotle (384–322 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. He adopted as reasonable suppositions the four Empedoclean elements, but added a fifth, aether. Nevertheless, these elements are not basic in Aristotle's mind. Rather they, like everything else in the visible world, are composed of the basic principles matter and form.

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

— Aristotle, Physics I:9:192a32

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

Seventeenth and eighteenth centuries

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

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

— René Descartes, Principles of Philosophy

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. They are independent things. In contrast, Aristotle defines matter and the formal/forming principle as complementary principles that together compose one independent thing (substance). In short, Aristotle defines matter (roughly speaking) as what things are actually made of (with a potential independent existence), but Descartes elevates matter to an actual independent thing in itself.

The continuity and difference between Descartes' 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.

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

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

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

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

19th and 20th centuries

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

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

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

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

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

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

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

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

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) to the frustration of theoreticians like Stephen Hawking. Interactions between quarks and leptons are the result of an exchange of force-carrying particles such as photons between quarks and leptons. The force-carrying particles are not themselves building blocks. As one consequence, mass and energy (which to our present knowledge cannot be created or destroyed) cannot always be related to matter (which can be created out of non-matter particles such as photons, or even out of pure energy, such as kinetic energy). Force mediators are usually not considered matter: the mediators of the electric force (photons) possess energy (see Planck relation) and the mediators of the weak force (W and Z bosons) have mass, but neither are considered matter either. However, while these quanta are not considered matter, they do contribute to the total mass of atoms, subatomic particles, and all systems that contain them.

Summary

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

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

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).

Consequences of Nazism

From Wikipedia, the free encyclopedia

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

Nazism and the acts of Adolf Hitler's Third Reich affected many countries, communities, and people before, during and after World War II. Nazi Germany's attempt to exterminate several groups viewed as subhuman by Nazi ideology was eventually stopped by the combined efforts of the wartime Allies headed by Britain, the Soviet Union, and the United States.

Jewish people

"Whoever wears this sign is an enemy of our people" – Parole der Woche, 1 July 1942

Of the world's 17 million Jews in 1939, more than a third were killed in the Holocaust. Of the three million Jews in Poland, the heartland of European Jewish culture, fewer than 350,000 survived. Most of the remaining Jews in Eastern and Central Europe became refugees, unable or unwilling to return to countries that became Soviet puppet states or countries that had betrayed them to the Nazis.

Poland

During World War II 85% of buildings in Warsaw were destroyed by German troops.

The Nazis intended to destroy the Polish nation completely. In 1941, the Nazi leadership decided that Poland was to be fully cleared of ethnic Poles within 10 to 20 years and settled by German colonists to further their policy of Lebensraum. From the beginning of the occupation, Germany's policy was to plunder and exploit Polish territory, turning it into a giant concentration camp for Poles who were to be exterminated as "Untermenschen". The policy of plunder and exploitation inflicted material losses to Polish industry, agriculture, infrastructure and cultural landmarks, with the cost of the destruction by Germans alone estimated at approximately €525 billion or $640 billion. Remaining Polish industry was mostly destroyed or transported to Russia by Soviet forces after the war.

The official Polish government report of war losses prepared in 1947 reported 6,028,000 war victims out of a population of 27,007,000 ethnic Poles and Jews alone. For political reasons, the report excluded the losses to the Soviet Union and the losses among Polish citizens of Ukrainian and Belarusian origin.

Poland's eastern border was significantly moved westwards to the Curzon Line. The resulting territorial loss of 188,000 km² (formerly populated by 5.3 million ethnic Poles) was to be compensated by the addition of 111,000 km² of former German territory east of the Oder–Neisse line (formerly populated by 11.4 million ethnic Germans). Kidnapping of Polish children by Germany also took place, in which children who were believed to hold German blood were taken away; around 20,000 Polish children were taken away from their parents. Out of the abducted only 10–15% returned home. Polish elites were decimated and over half of the Polish intelligentsia were murdered. Some professions lost 20–50% of their members, for example 58% of Polish lawyers, 38% of medical doctors and 28% of university workers were exterminated by the Nazis. The Polish capital Warsaw was razed by German forces and most of its old and newly acquired cities lay in ruins (e.g. Wrocław) or lost to the Soviet Union (e.g. Lwów). In addition Poland became a Soviet satellite state, remaining under a Soviet-controlled communist government until 1989. Russian troops did not withdraw from Poland until 1993, after the collapse of the Soviet Union in 1991.

Central Europe

As a consequence of the war and Soviet occupation, Central European countries found themselves under the "Soviet sphere of influence" (as agreed upon at the Yalta Conference). Immediately following the war, Soviet style socialist governments were established in all of these countries and any forms of western style democracy that existed before the war were abolished. As a result of the Warsaw Pact not participating in the Marshall Plan, as well as industrial infrastructure being taken by the Soviets, economic recovery was slowed significantly.

Soviet Union

About 26 million Soviet citizens perished as a result of the Nazi invasion of the Soviet Union, including around 10,651,000 soldiers who died in battle against Hitler's armies or died in POW camps. According to Russian historian Vadim Erlikman, Soviet losses amounted to 26.5 million war related deaths. Millions of civilians also died from starvation, exposure, atrocities, and massacres, and a huge area of the Soviet Union from the suburbs of Moscow and the Volga River to the western border had been destroyed, depopulated, and reduced to rubble. The mass death and destruction there badly damaged the Soviet economy, society, and national psyche. The death toll included c.a. 1.5 million Soviet Jews killed by the German invaders. The mass destruction and mass murder was one of the reasons why the Soviet Union installed satellite states in Central Europe; as the government hoped to use the countries as a buffer zone against any new invasions from the West. This helped break down the wartime alliance between the Soviet Union and the Western Allies, setting the stage for the Cold War, which lasted until 1989, two years before the dissolution of the Soviet Union in 1991. Soviet culture in the 1950s was defined by results of the Great Patriotic War.

Close to 60% of the European war dead were from the Soviet Union. Military losses of 10.6 million include 7.6 million killed or missing in action and 2.6 million POW dead, plus 400,000 paramilitary and Soviet partisan losses. Civilian deaths totaled 15.9 million which included 1.5 million from military actions. 7.1 million victims of Nazi genocide and reprisals; 1.8 million deported to Germany for forced labor; and 5.5 million famine and disease deaths. Additional famine deaths which totaled 1 million during 1946–47 are not included here. These losses are for the entire territory of the USSR including territories annexed in 1939–40.

To the north, the Germans reached Leningrad (Saint Petersburg) in August 1941. The city was surrounded on 8 September, beginning a 900-day siege during which about 1.2 million citizens perished.

Of the 5.7 million Soviet prisoners of war captured by the Germans, more than 3.5 million had died while in German captivity by the end of the war. On 11 February 1945, at the conclusion of the Yalta Conference, the United States and United Kingdom signed a Repatriation Agreement with the USSR. The interpretation of this Agreement resulted in the forcible repatriation of all Soviets regardless of their wishes. Millions of Soviet POWs and forced laborers transported to Germany are believed to have been treated as traitors, cowards and deserters on their return to the USSR (see Order No. 270). Statistical data from Soviet archives, that became available after Perestroika, attest that the overall increase of the Gulag population was minimal during 1945–46 and only 272,867 of repatriated Soviet POWs and civilians (out of 4,199,488) were imprisoned.

Belarus

Belarus lost a quarter of its pre-war population, including almost all of its intellectual elite, and 90% of the country’s Jewish population. Following bloody encirclement battles, all of the present-day Belarus territory was occupied by the Germans by the end of August 1941. The Nazis imposed a brutal regime, deporting some 380,000 young people for slave labour, and killing hundreds of thousands of other civilians. At least 5,295 Belarusian settlements were destroyed by the Nazis and some or all their inhabitants killed (out of 9,200 settlements that were burned or otherwise destroyed in Belarus during World War II). More than 600 villages like Khatyn were burned with their entire population. More than 209 cities and towns (out of 270 total) were destroyed. Himmler had pronounced a plan according to which 3/4 of Belarusian population was designated for "eradication" and 1/4 of racially cleaner population (blue eyes, light hair) would be allowed to serve Germans as slaves (Ostarbeiter).

Some recent estimates raise the number of Belarusians who perished in War to "3 million 650 thousand people, unlike the former 2.2 million. That is to say not every fourth inhabitant but about 40% of the pre-war Belarusian population perished (considering the present-day borders of Belarus)." This compares to 15% of Poland's post war borders and 19% of Ukrainian population in post war border and comparing to 2% of Czechoslovakian population that perished in post war borders.

Ukraine

Estimates on population losses in Ukraine range from 7 to 11 million. More than 700 cities and towns and 28,000 villages were destroyed.

Yugoslavia

Due to their strong opposition to Nazism, Serbs were considered enemies of Nazi Germany. Alongside Jews, Serbs were killed and expelled in wartime Yugoslavia.

It is estimated that 1,700,000 people were killed during World War II in Yugoslavia from 1941 to 1945. Very high losses were among Serbs who lived in Bosnia and Croatia, as well as Jewish and Romani minorities, with losses also high among all other non-collaborating populations. In the summer of 1941, the Serbian uprising came at the time of the German invasion of the USSR. The Nazi response was the execution of 100 Serbian civilians for every killed soldier and 50 Serbian civilians for every wounded soldier. The Yugoslav Partisans fought both a guerrilla campaign against the Axis occupiers and a civil war against the Chetniks. The Independent State of Croatia was established as a Nazi puppet-state, ruled by the fascist militia known as the Ustaše. During this time the Independent State of Croatia created extermination camps for anti-fascists, communists, Serbs, Muslims, Romanies and Jews, one of the most infamous being the Jasenovac concentration camp. A large number of men, women and children, mostly Serbs, were murdered in these camps.

Western Europe

Britain and France, two of the victors, were exhausted and bankrupted by the war, and Britain lost its superpower status. With Germany and Japan in ruins as well, the world was left with two dominant powers, the United States and the Soviet Union. Economic and political reality in Western Europe would soon force the dismantling of the European colonial empires, especially in Africa and Asia.

One of the most important political consequences of the Nazi experience in Western Europe was the establishment of new political alliances which eventually became the European Union and an international military alliance of European countries known as NATO to counterbalance the Soviets' Warsaw Pact and until communist rule in Eastern Europe ended in the late 1980s.

The Communists emerged from the war sharing the vast prestige of the victorious Soviet armed forces, and for a while it looked as though they might take power in France, Italy and Greece. The West quickly acted to prevent this from happening, hence the Cold War.

Greece

In Greece, the German occupation (April 1941 – October 1944) destroyed the economy through war reparations, plundering of the country's resources and hyper-inflation. In addition, the Germans left most of the country's infrastructure in ruins as they withdrew in 1944. As a result of an Allied blockade and German indifference to local needs, the first winter of the occupation was marked by widespread famine in the main urban centres, with as many as 300,000 civilians dead from starvation. Although these levels of starvation were not repeated in the following years, malnourishment was common throughout the occupation. In addition, thousands more were executed by German forces as reprisals for partisan activities. As part of the Holocaust, Greece's Jewish community was almost wiped out, especially the large Sephardi community of Thessaloniki, which had earned the city the sobriquet "Mother of Israel" and had first settled there in the early 16th century at the invitation of the then-ruling Ottoman Empire. In total, at least 81% (ca. 60,000) of Greece's total pre-war Jewish population died.

The bitterest and longest-lasting legacy of the German occupation was the social upheaval it wrought. The old political elites were sidelined, and the Resistance against the Axis brought to the fore the leftist National Liberation Front (EAM), arguably the country's first true mass-movement, where the Communists played a central role. In an effort to oppose its growing influence, the Germans encouraged the pre-war conservative establishment to confront it, and allowed the creation of armed units. As elsewhere in Eastern Europe, in the last year of the occupation, conditions in Greece often approximated a civil war between EAM and other powers. The rift would become permanent in December 1944, when EAM and the British-backed government clashed in Athens, and again in a fully fledged civil war from 1946–1949.

Germany

Lost territories and postwar occupation zones in Germany

More than 8 million Germans, including almost 2 million civilians, died during World War II (see World War II casualties). After the end of the war in Europe additional casualties were incurred during the Allied occupation and also during the population expulsions that followed.

After the war, the German people were often viewed with contempt because they were blamed by other Europeans for Nazi crimes. Germans visiting abroad, particularly in the 1950s and 1960s, attracted insults from locals, and from foreigners who may have lost their families or friends in the atrocities. Today in Europe and worldwide (particularly in countries that fought against the Axis), Germans may be scorned by elderly people who were alive to experience the atrocities committed by Nazi Germans during World War II. This resulted in a feeling of controversy for many Germans, causing numerous discussions and rows among scholars and politicians in Post-War West Germany (for example, the "Historikerstreit" [historians' argument] in the 1980s) and after Reunification. Here, the discussion was mainly about the role that the unified Germany should play in the world and in Europe. Bernard Schlink's novel The Reader concerns how post-war Germans dealt with the issue.

Following World War II, the Allies embarked on a program of denazification, but as the Cold War intensified these efforts were curtailed in the west.

Germany itself and the German economy were devastated, with great parts of most major cities destroyed by the bombings of the Allied forces, sovereignty taken away by the Allies and the territory filled with millions of refugees from the former eastern provinces which the Allies had decided were to be annexed by the Soviet Union and Poland, moving the eastern German border westwards to the Oder-Neisse line and effectively reducing Germany in size by roughly 25% (see also Potsdam Conference). The remaining parts of Germany were divided among the Allies and occupied by British (the north-west), French (the south-west), American (the south) and Soviet (the east) troops.

The expulsions of Germans from the lost areas in the east (see also Former eastern territories of Germany), the Sudetenland, and elsewhere in eastern Europe went on for several years. The number of Germans expelees totaled roughly 15,000,000. Estimates of number of deaths in connection with expulsion range from under 500,000 to 3 million.

After a short time, the Allies broke over ideological problems (Communism versus Capitalism), and thus both sides established their own spheres of influence, creating a previously non-existent division in Germany between East and West (although the division largely followed the borders of states which had existed in Germany before Bismarck's unification less than 100 years before).

A constitution for East Germany was drafted on 30 May 1949. Wilhelm Pieck, a leader of the Socialist Unity Party of Germany (SED) party (which was created by a forced merger of the Social Democratic Party of Germany (SPD) and Communist Party of Germany (KPD) in the Soviet sector), was elected first President of the German Democratic Republic.

West Germany, (officially: Federal Republic of Germany, FRG – this is still the official name of the unified Germany today) received (de facto) semi-sovereignty in 1949, as well as a constitution, called the Grundgesetz (Basic Law). The document was not called a Constitution officially, as at this point, it was still hoped that the two German states would be reunited in the near future.

The first free elections in West Germany were held in 1949, which were won by the Christian Democratic Party of Germany (CDU) (conservatives) by a slight margin. Konrad Adenauer, a member of the CDU, was the first Bundeskanzler (Chancellor) of West Germany.

Both German states introduced, in 1948, their own money, colloquially called West-Mark and Ost-Mark (Western Mark and Eastern Mark).

Foreign troops still remain in Germany today, for example Ramstein Air Base, but the majority of troops left following the end of the Cold War (By 1994 for Soviet troops, mandated under the terms of the Treaty on the Final Settlement With Respect to Germany and in the mid-1990s for Western forces). The Bush Administration in the United States in 2004 stated intentions to withdraw most of the remaining American troops out of Germany in the coming years. During the years 1950–2000 more than 10,000,000 U.S. military personnel were stationed in Germany.

The West German economy was by the mid 1950s rebuilt thanks to the abandonment in mid-1947 of some of the last vestiges of the Morgenthau Plan and to fewer war reparations imposed on West Germany (see also Wirtschaftswunder). After lobbying by the Joint Chiefs of Staff, and Generals Clay and Marshall, the Truman administration realized that economic recovery in Europe could not go forward without the reconstruction of the German industrial base on which it previously had been dependent. In July 1947, President Harry S. Truman rescinded on "national security grounds" the punitive JCS 1067, which had directed the U.S. forces of occupation in Germany to "take no steps looking toward the economic rehabilitation of Germany." It was replaced by JCS 1779, which instead stressed that "[a]n orderly, prosperous Europe requires the economic contributions of a stable and productive Germany."

The dismantling of factories in the western zones, for further transport to the Soviet Union as reparations, was in time halted as frictions grew between East and West. Limits were placed on permitted levels of German production in order to prevent resurgence of German militarism, part of which included severely restricting German steel production and affected the rest of the German economy very negatively (see "The industrial plans for Germany"). Dismantling of factories by France and Great Britain as reparations and for the purpose of lowering German war and economic potential under the "level of industry plans" took place (halted in 1951), but to nowhere near the scale of the dismantling and transport to the Soviet Union of factories in the eastern zone of occupation. The Eastern Bloc did not accept the Marshall Plan, denouncing it as American economic imperialism, and thus it (East Germany included) recovered much more slowly than their Western counterparts. German political and economic control of its main remaining centers of industry was reduced, the Ruhr area was under international control. The Ruhr Agreement was imposed on the Germans as a condition for permitting them to establish the Federal Republic of Germany. In the end, the beginning of the Cold War led to increased German control of the area, although permanently limited by the pooling of German coal and steel into a multinational community in 1951 (see European Coal and Steel Community). The neighboring Saar area, containing much of Germany's remaining coal deposits, handed over by the U. S. to French economic administration as a protectorate in 1947 and did not politically return to Germany until January 1957, with economic reintegration occurring a few years later. (see also the Monnet Plan). Upper Silesia, Germany's second largest center of mining and industry, had been handed over to Poland at the Potsdam Conference.

The Allies confiscated intellectual property of great value, all German patents, both in Germany and abroad, and used them to strengthen their own industrial competitiveness by licensing them to Allied companies. Beginning immediately after the German surrender and continuing for the next two years the U.S. pursued a vigorous program to harvest all technological and scientific know-how as well as all patents in Germany. John Gimbel comes to the conclusion, in his book Science Technology and Reparations: Exploitation and Plunder in Postwar Germany, that the "intellectual reparations" taken by the U.S. and the UK amounted to close to $10 billion. During the more than two years that this policy was in place, no industrial research in Germany could take place, as any results would have been automatically available to overseas competitors who were encouraged by the occupation authorities to access all records and facilities. Meanwhile, thousands of the best German researchers were being put to work in the Soviet Union and in the U.S. (see also Operation Paperclip)

For several years following the surrender German nutritional levels were very low, resulting in very high mortality rates. Throughout all of 1945 the U.S. forces of occupation ensured that no international aid reached ethnic Germans. It was directed that all relief went to non-German displaced persons, liberated Allied POWs, and concentration camp inmates. During 1945 it was estimated that the average German civilian in the US and UK occupation zones received 1200 calories a day. Meanwhile, non-German displaced persons were receiving 2300 calories through emergency food imports and Red Cross help. In early October 1945 the UK government privately acknowledged in a cabinet meeting that German civilian adult death rates had risen to 4 times the pre-war levels and death rates amongst the German children had risen by 10 times the pre-war levels. The German Red Cross was dissolved, and the International Red Cross and the few other allowed international relief agencies were kept from helping Germans through strict controls on supplies and travel. The few agencies permitted to help Germans, such as the indigenous Caritasverband, were not allowed to use imported supplies. When the Vatican attempted to transmit food supplies from Chile to German infants the US State Department forbade it. The German food situation reached its worst during the very cold winter of 1946–1947 when German calorie intake ranged from 1,000–1,500 calories per day, a situation made worse by severe lack of fuel for heating. Meanwhile, the Allies were well fed, average adult calorie intake was; U.S. 3200–3300; UK 2900; U.S. Army 4000. German infant mortality rate was twice that of other nations in Western Europe until the close of 1948.

As agreed by the Allies at the Yalta conference Germans were used as forced labor as part of the reparations to be extracted to the countries ruined by Nazi aggression. By 1947 it is estimated that 4,000,000 Germans (both civilians and POWs) were being used as forced labor by the U.S., France, the UK and the Soviet Union. German prisoners were for example forced to clear minefields in France and the low countries. By December 1945 it was estimated by French authorities that 2,000 German prisoners were being killed or maimed each month in accidents. In Norway the last available casualty record, from 29 August 1945, shows that by that time a total of 275 German soldiers died while clearing mines, while 392 had been maimed. Death rates for the German civilians doing forced labor in the Soviet Union ranged between 19% and 39%, depending on category. (see also Forced labor of Germans in the Soviet Union).

Norman Naimark writes in The Russians in Germany: A History of the Soviet Zone of Occupation, 1945–1949, that although the exact number of women and girls who were raped by members of the Red Army in the months preceding and years following the capitulation will never be known, their numbers are likely in the hundreds of thousands, quite possibly as high as the 2,000,000 victims estimate made by Barbara Johr, in Befreier und Befreite. Many of these victims were raped repeatedly. Naimark states that not only had each victim to carry the trauma with her for the rest of her days, it inflicted a massive collective trauma on the East German nation (the German Democratic Republic). Naimark concludes "The social psychology of women and men in the soviet zone of occupation was marked by the crime of rape from the first days of occupation, through the founding of the GDR in the fall of 1949, until – one could argue – the present."

The post-war hostility shown to the German people is exemplified in the fate of the War children, sired by German soldiers with women from the local population in nations such as Norway where the children and their mothers after the war had to endure many years of abuse. In the case of Denmark the hostility felt towards all things German also showed itself in the treatment of German refugees during the years 1945 to 1949. During 1945 alone 7000 German children under the age of 5 died as a result of being denied sufficient food and denied medical attention by Danish doctors who were afraid that rendering aid to the children of the former enemy would be seen as an unpatriotic act. Many children died of easily treatable ailments. As a consequence "more German refugees died in Danish camps, "than Danes did during the entire war.""

During the Cold War, it was difficult for West Germans to visit East German relatives and friends and impossible vice versa. For East Germans, especially after the building of the Berlin Wall on 13 August 1961 and until Hungary opened up its border to the West in the late 1980s, thus allowing hundreds of thousands of vacationing East Germans to flee into Western Europe, it was only possible to get to West Germany by illegally fleeing across heavily fortified and guarded border areas.

44 years after the end of World War II, the Berlin Wall fell on 9 November 1989. The East and West parts of Germany were reunited on 3 October 1990.

Economic and social divisions between East and West Germany continue to play a major role in politics and society in Germany at present. It is likely the contrast between the generally well-off and economically diverse West and the weaker, heavy-industry reliant East will continue at least into the foreseeable future.