Energy

context: In physics, energy is a property of objects which can be transferred to other objects or converted into different forms. The "ability of a system to perform work" is a common description, but it is difficult to give one single comprehensive definition of energy because of its many forms. For instance, in SI units, energy is measured in joules, and one joule is defined "mechanically", being the energy transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton.[note 1] However, there are many other definitions of energy, depending on the context, such as thermal energy, radiant energy, electromagnetic, nuclear, etc., where definitions are derived that are the most convenient.
qas: answers: text: energy
question: What is a property of objects which can be transferred to other objects or converted into different forms?

answers: text: joules
question: In SI units, energy is measured in what measurement?

answers: text: the energy transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton
question: Mechanically, one joule is defined as what?

context: Common energy forms include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature. All of the many forms of energy are convertible to other kinds of energy. In Newtonian physics, there is a universal law of conservation of energy which says that energy can be neither created nor be destroyed; however, it can change from one form to another.
qas: answers: text: kinetic energy of a moving object
question: Common energy forms include what?

answers: text: destroyed
question: In Newtonian physics, there is a universal law that says energy can be neither created nor what?

answers: text: Newtonian physics
question: What law states, in part, that energy can change from one form to another?

context: For "closed systems" with no external source or sink of energy, the first law of thermodynamics states that a system's energy is constant unless energy is transferred in or out by mechanical work or heat, and that no energy is lost in transfer. This means that it is impossible to create or destroy energy. While heat can always be fully converted into work in a reversible isothermal expansion of an ideal gas, for cyclic processes of practical interest in heat engines the second law of thermodynamics states that the system doing work always loses some energy as waste heat. This creates a limit to the amount of heat energy that can do work in a cyclic process, a limit called the available energy. Mechanical and other forms of energy can be transformed in the other direction into thermal energy without such limitations. The total energy of a system can be calculated by adding up all forms of energy in the system.
qas: answers: text: by adding up all forms of energy in the system
question: How can the total energy of a system be calculated?

answers: text: available energy
question: The limit to the amount of heat energy that can do work in a cyclic process is known as what?

answers: text: heat
question: What can be fully converted into work in a reversible isothermal expansion of an ideal gas?

answers: text: second law of thermodynamics
question: What states that the system doing work always loses some energy as waste heat?

context: Examples of energy transformation include generating electric energy from heat energy via a steam turbine, or lifting an object against gravity using electrical energy driving a crane motor. Lifting against gravity performs mechanical work on the object and stores gravitational potential energy in the object. If the object falls to the ground, gravity does mechanical work on the object which transforms the potential energy in the gravitational field to the kinetic energy released as heat on impact with the ground. Our Sun transforms nuclear potential energy to other forms of energy; its total mass does not decrease due to that in itself (since it still contains the same total energy even if in different forms), but its mass does decrease when the energy escapes out to its surroundings, largely as radiant energy.
qas: answers: text: generating electric energy from heat energy via a steam turbine
question: Give one example of energy transformation.

answers: text: Sun
question: What transforms nuclear potential energy to other forms of energy?

answers: text: lifting an object against gravity using electrical energy driving a crane motor
question: What is another example of energy transformation?

context: The total energy of a system can be subdivided and classified in various ways. For example, classical mechanics distinguishes between kinetic energy, which is determined by an object's movement through space, and potential energy, which is a function of the position of an object within a field. It may also be convenient to distinguish gravitational energy, thermal energy, several types of nuclear energy (which utilize potentials from the nuclear force and the weak force), electric energy (from the electric field), and magnetic energy (from the magnetic field), among others. Many of these classifications overlap; for instance, thermal energy usually consists partly of kinetic and partly of potential energy.
qas: answers: text: kinetic energy
question: What is determined by an object's movement through space?

answers: text: thermal energy
question: What usually consists partly of kinetic and partly of potential energy?

answers: text: potential energy
question: What is a function of the position of an object within a field?

context: Some types of energy are a varying mix of both potential and kinetic energy. An example is mechanical energy which is the sum of (usually macroscopic) kinetic and potential energy in a system. Elastic energy in materials is also dependent upon electrical potential energy (among atoms and molecules), as is chemical energy, which is stored and released from a reservoir of electrical potential energy between electrons, and the molecules or atomic nuclei that attract them.[need quotation to verify].The list is also not necessarily complete. Whenever physical scientists discover that a certain phenomenon appears to violate the law of energy conservation, new forms are typically added that account for the discrepancy.
qas: answers: text: Elastic energy in materials
question: What is dependent upon electrical potential energy?

answers: text: from a reservoir of electrical potential energy between electrons
question: Where is chemical energy stored and released?

answers: text: kinetic
question: Some types of energy are a varying mix of potential and what other kind of energy?

context: In the late 17th century, Gottfried Leibniz proposed the idea of the Latin: vis viva, or living force, which defined as the product of the mass of an object and its velocity squared; he believed that total vis viva was conserved. To account for slowing due to friction, Leibniz theorized that thermal energy consisted of the random motion of the constituent parts of matter, a view shared by Isaac Newton, although it would be more than a century until this was generally accepted. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two.
qas: answers: text: vis viva
question: What is a term for living force?

answers: text: vis viva
question: What is defined as the product of mass of an object and its velocity squared?

answers: text: Gottfried Leibniz
question: Who proposed the idea of the Latin: vis viva?

answers: text: late 17th century
question: In what century did Leibniz propose the idea of Latin: vis viva?

answers: text: Isaac Newton
question: Who shared Leibniz's view that thermal energy consisted of random motion of the constituent parts of matter?

context: In 1807, Thomas Young was possibly the first to use the term "energy" instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described "kinetic energy" in 1829 in its modern sense, and in 1853, William Rankine coined the term "potential energy". The law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for some years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity, such as momentum. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat.
qas: answers: text: Thomas Young
question: Who was possibly the first to use the term "energy" instead of vis viva?

answers: text: 1807
question: When did Thomas Young use the term "energy" instead of vis viva?

answers: text: William Rankine
question: Who coined the term "potential energy?"

answers: text: James Prescott Joule
question: Who discovered the link between mechanical work and the generation of heat?

answers: text: 19th century
question: When was the law of conservation of energy first postulated?

context: These developments led to the theory of conservation of energy, formalized largely by William Thomson (Lord Kelvin) as the field of thermodynamics. Thermodynamics aided the rapid development of explanations of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, and Walther Nernst. It also led to a mathematical formulation of the concept of entropy by Clausius and to the introduction of laws of radiant energy by Jožef Stefan. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time. Thus, since 1918, theorists have understood that the law of conservation of energy is the direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time.
qas: answers: text: William Thomson
question: Who largely formalized the developments that led to the theory of conservation of energy?

answers: text: Thermodynamics
question: What aided the rapid development of explanations of chemical processes by Clausius, Gibbs and Nernst?

answers: text: Jožef Stefan
question: Who developed the concept of the introduction of laws of radiant energy?

answers: text: Noether's theorem
question: What states that the conservation of energy is a consequence of the fact that the laws of physics do not change over time?

context: Another energy-related concept is called the Lagrangian, after Joseph-Louis Lagrange. This formalism is as fundamental as the Hamiltonian, and both can be used to derive the equations of motion or be derived from them. It was invented in the context of classical mechanics, but is generally useful in modern physics. The Lagrangian is defined as the kinetic energy minus the potential energy. Usually, the Lagrange formalism is mathematically more convenient than the Hamiltonian for non-conservative systems (such as systems with friction).
qas: answers: text: Lagrangian
question: What is another energy-related concept?

answers: text: Joseph-Louis Lagrange
question: Who is the Lagrangian named after?

answers: text: Lagrangian
question: What is defined as the kinetic energy minus the potential energy?

answers: text: Lagrange formalism
question: Is the Lagrange formalism or the Hamiltonian more convenient for non-conservative systems?

context: Noether's theorem (1918) states that any differentiable symmetry of the action of a physical system has a corresponding conservation law. Noether's theorem has become a fundamental tool of modern theoretical physics and the calculus of variations. A generalisation of the seminal formulations on constants of motion in Lagrangian and Hamiltonian mechanics (1788 and 1833, respectively), it does not apply to systems that cannot be modeled with a Lagrangian; for example, dissipative systems with continuous symmetries need not have a corresponding conservation law.
qas: answers: text: 1918
question: When was Noether's theorem created?

answers: text: Noether's theorem
question: What states that any differentiable symmetry of the action of a physical system has a corresponding conservation law?

answers: text: Noether's theorem
question: What has become a fundamental tool of modern theoretical physics and the calculus of variations?

context: In the context of chemistry, energy is an attribute of a substance as a consequence of its atomic, molecular or aggregate structure. Since a chemical transformation is accompanied by a change in one or more of these kinds of structure, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e−E/kT – that is the probability of molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation.The activation energy necessary for a chemical reaction can be in the form of thermal energy.
qas: answers: text: energy
question: In the context of chemistry, what is an attribute of a substance as a consequence of it's atomic, molecular or aggregate structure?

answers: text: Chemical reactions
question: What is not possible unless the reactants surmount an energy barrier known as the activation energy?

answers: text: e−E/kT
question: What is the probability of molecule to have energy greater than or equal to E at the given temperature T?

answers: text: Boltzmann's
question: Who created the population factor e-E/kT?

answers: text: Arrhenius equation
question: What is the exponential dependence of a reaction rate on temperature?

context: In biology, energy is an attribute of all biological systems from the biosphere to the smallest living organism. Within an organism it is responsible for growth and development of a biological cell or an organelle of a biological organism. Energy is thus often said to be stored by cells in the structures of molecules of substances such as carbohydrates (including sugars), lipids, and proteins, which release energy when reacted with oxygen in respiration. In human terms, the human equivalent (H-e) (Human energy conversion) indicates, for a given amount of energy expenditure, the relative quantity of energy needed for human metabolism, assuming an average human energy expenditure of 12,500 kJ per day and a basal metabolic rate of 80 watts. For example, if our bodies run (on average) at 80 watts, then a light bulb running at 100 watts is running at 1.25 human equivalents (100 ÷ 80) i.e. 1.25 H-e. For a difficult task of only a few seconds' duration, a person can put out thousands of watts, many times the 746 watts in one official horsepower. For tasks lasting a few minutes, a fit human can generate perhaps 1,000 watts. For an activity that must be sustained for an hour, output drops to around 300; for an activity kept up all day, 150 watts is about the maximum. The human equivalent assists understanding of energy flows in physical and biological systems by expressing energy units in human terms: it provides a "feel" for the use of a given amount of energy.
qas: answers: text: energy
question: In biology, what is an attribute of all biological systems from the biosphere to the smallest living organism?

answers: text: Energy
question: What is often said to be stored by cells in the structures of molecules of substances such as carbohydrates, lipids and proteins?

answers: text: Human energy conversion
question: What does H-e stand for?

answers: text: 746 watts
question: How many watts is in one official horsepower?

context: Sunlight is also captured by plants as chemical potential energy in photosynthesis, when carbon dioxide and water (two low-energy compounds) are converted into the high-energy compounds carbohydrates, lipids, and proteins. Plants also release oxygen during photosynthesis, which is utilized by living organisms as an electron acceptor, to release the energy of carbohydrates, lipids, and proteins. Release of the energy stored during photosynthesis as heat or light may be triggered suddenly by a spark, in a forest fire, or it may be made available more slowly for animal or human metabolism, when these molecules are ingested, and catabolism is triggered by enzyme action.
qas: answers: text: Sunlight
question: What is also captured by plants as chemical potential energy in photosynthesis?

answers: text: oxygen
question: What do plants release during photosynthesis?

answers: text: Release of the energy stored during photosynthesis
question: What may be triggered suddenly by a spark?

answers: text: carbon dioxide and water
question: What are two low-energy compounds?

context: Any living organism relies on an external source of energy—radiation from the Sun in the case of green plants, chemical energy in some form in the case of animals—to be able to grow and reproduce. The daily 1500–2000 Calories (6–8 MJ) recommended for a human adult are taken as a combination of oxygen and food molecules, the latter mostly carbohydrates and fats, of which glucose (C6H12O6) and stearin (C57H110O6) are convenient examples. The food molecules are oxidised to carbon dioxide and water in the mitochondria
qas: answers: text: an external source of energy
question: What does any living organism rely on to be able to grow and reproduce?

answers: text: 1500–2000
question: How many daily calories are recommended for a human adult?

answers: text: mitochondria
question: Where are food molecules oxidised to carbon dioxide and water?

context: It would appear that living organisms are remarkably inefficient (in the physical sense) in their use of the energy they receive (chemical energy or radiation), and it is true that most real machines manage higher efficiencies. In growing organisms the energy that is converted to heat serves a vital purpose, as it allows the organism tissue to be highly ordered with regard to the molecules it is built from. The second law of thermodynamics states that energy (and matter) tends to become more evenly spread out across the universe: to concentrate energy (or matter) in one specific place, it is necessary to spread out a greater amount of energy (as heat) across the remainder of the universe ("the surroundings").[note 3] Simpler organisms can achieve higher energy efficiencies than more complex ones, but the complex organisms can occupy ecological niches that are not available to their simpler brethren. The conversion of a portion of the chemical energy to heat at each step in a metabolic pathway is the physical reason behind the pyramid of biomass observed in ecology: to take just the first step in the food chain, of the estimated 124.7 Pg/a of carbon that is fixed by photosynthesis, 64.3 Pg/a (52%) are used for the metabolism of green plants, i.e. reconverted into carbon dioxide and heat.
qas: answers: text: The second law of thermodynamics
question: What states that energy tends to become more evenly spread out across the universe?

answers: text: living organisms
question: What are remarkably inefficient in their use of the energy they receive?

answers: text: ecological niches
question: Complex organisms can occupy this, that are not available to their simpler brethern?

context: Sunlight may be stored as gravitational potential energy after it strikes the Earth, as (for example) water evaporates from oceans and is deposited upon mountains (where, after being released at a hydroelectric dam, it can be used to drive turbines or generators to produce electricity). Sunlight also drives many weather phenomena, save those generated by volcanic events. An example of a solar-mediated weather event is a hurricane, which occurs when large unstable areas of warm ocean, heated over months, give up some of their thermal energy suddenly to power a few days of violent air movement.
qas: answers: text: Sunlight
question: This drives many weather phenomena, save those generated by volcanic events.

answers: text: after it strikes the Earth
question: When may sunlight be stored as gravitational potential energy?

answers: text: hurricane
question: What is an example of a solar-mediated weather event?

answers: text: hurricane
question: What occurs when large unstable areas of warm ocean, heated over months, give up some of their thermal energy suddenly to power a few days of violent air movement?

context: In a slower process, radioactive decay of atoms in the core of the Earth releases heat. This thermal energy drives plate tectonics and may lift mountains, via orogenesis. This slow lifting represents a kind of gravitational potential energy storage of the thermal energy, which may be later released to active kinetic energy in landslides, after a triggering event. Earthquakes also release stored elastic potential energy in rocks, a store that has been produced ultimately from the same radioactive heat sources. Thus, according to present understanding, familiar events such as landslides and earthquakes release energy that has been stored as potential energy in the Earth's gravitational field or elastic strain (mechanical potential energy) in rocks. Prior to this, they represent release of energy that has been stored in heavy atoms since the collapse of long-destroyed supernova stars created these atoms.
qas: answers: text: Earthquakes
question: What releases stored elastic potential energy in rocks?

answers: text: heat
question: What does radioactive decay of atoms in the core of the Earth release?

answers: text: thermal energy
question: What drives plate tectonics and may lift mountains via orogenesis?

answers: text: elastic strain
question: What is mechanical potential energy?

context: In cosmology and astronomy the phenomena of stars, nova, supernova, quasars and gamma-ray bursts are the universe's highest-output energy transformations of matter. All stellar phenomena (including solar activity) are driven by various kinds of energy transformations. Energy in such transformations is either from gravitational collapse of matter (usually molecular hydrogen) into various classes of astronomical objects (stars, black holes, etc.), or from nuclear fusion (of lighter elements, primarily hydrogen). The nuclear fusion of hydrogen in the Sun also releases another store of potential energy which was created at the time of the Big Bang. At that time, according to theory, space expanded and the universe cooled too rapidly for hydrogen to completely fuse into heavier elements. This meant that hydrogen represents a store of potential energy that can be released by fusion. Such a fusion process is triggered by heat and pressure generated from gravitational collapse of hydrogen clouds when they produce stars, and some of the fusion energy is then transformed into sunlight.
qas: answers: text: stellar phenomena
question: What is driven by various kinds of energy transformations?

answers: text: nuclear fusion of hydrogen in the Sun
question: What releases another store of potential energy which was created at the time of the Big Bang?

answers: text: Big Bang
question: What theory states that space expanded and the universe cooled too rapidly for hydrogen to completely fuse into heavier elements?

answers: text: fusion
question: Hydrogen represents a store of potential energy that can be released by what?

context: In quantum mechanics, energy is defined in terms of the energy operator as a time derivative of the wave function. The Schrödinger equation equates the energy operator to the full energy of a particle or a system. Its results can be considered as a definition of measurement of energy in quantum mechanics. The Schrödinger equation describes the space- and time-dependence of a slowly changing (non-relativistic) wave function of quantum systems. The solution of this equation for a bound system is discrete (a set of permitted states, each characterized by an energy level) which results in the concept of quanta. In the solution of the Schrödinger equation for any oscillator (vibrator) and for electromagnetic waves in a vacuum, the resulting energy states are related to the frequency by Planck's relation:  (where  is Planck's constant and  the frequency). In the case of an electromagnetic wave these energy states are called quanta of light or photons.
qas: answers: text: energy
question: In quantum mechanics, what is defined in terms of the energy operator as a time derivative of the wave function?

answers: text: The Schrödinger equation
question: What equates the energy operator to the full energy of a particle or a system?

answers: text: The Schrödinger equation
question: What describes the space-and-time dependence of a slowly changing wave function of quantum systems?

context: For example, consider electron–positron annihilation, in which the rest mass of individual particles is destroyed, but the inertia equivalent of the system of the two particles (its invariant mass) remains (since all energy is associated with mass), and this inertia and invariant mass is carried off by photons which individually are massless, but as a system retain their mass. This is a reversible process – the inverse process is called pair creation – in which the rest mass of particles is created from energy of two (or more) annihilating photons. In this system the matter (electrons and positrons) is destroyed and changed to non-matter energy (the photons). However, the total system mass and energy do not change during this interaction.
qas: answers: text: electron–positron annihilation
question: What is it called when the rest mass of individual particles is destroyed but the inertia equivalent of the system of the two particles remains?

answers: text: pair creation
question: What is the inverse process called?

answers: text: pair creation
question: What is the process in which the rest mass of particles is created from energy of two or more annihilating photons?

context: There are strict limits to how efficiently heat can be converted into work in a cyclic process, e.g. in a heat engine, as described by Carnot's theorem and the second law of thermodynamics. However, some energy transformations can be quite efficient. The direction of transformations in energy (what kind of energy is transformed to what other kind) is often determined by entropy (equal energy spread among all available degrees of freedom) considerations. In practice all energy transformations are permitted on a small scale, but certain larger transformations are not permitted because it is statistically unlikely that energy or matter will randomly move into more concentrated forms or smaller spaces.
qas: answers: text: Carnot's theorem
question: What states that there are strict limits to how efficiently heat can be converted into a work in a cyclic process?

answers: text: what kind of energy is transformed to what other kind
question: What is the direction of transformations in energy?

answers: text: direction of transformations in energy
question: What is often determined by entropy considerations?

answers: text: because it is statistically unlikely that energy or matter will randomly move into more concentrated forms or smaller spaces
question: Why are certain larger transformations not permitted?

context: Energy transformations in the universe over time are characterized by various kinds of potential energy that has been available since the Big Bang later being "released" (transformed to more active types of energy such as kinetic or radiant energy) when a triggering mechanism is available. Familiar examples of such processes include nuclear decay, in which energy is released that was originally "stored" in heavy isotopes (such as uranium and thorium), by nucleosynthesis, a process ultimately using the gravitational potential energy released from the gravitational collapse of supernovae, to store energy in the creation of these heavy elements before they were incorporated into the solar system and the Earth. This energy is triggered and released in nuclear fission bombs or in civil nuclear power generation. Similarly, in the case of a chemical explosion, chemical potential energy is transformed to kinetic energy and thermal energy in a very short time. Yet another example is that of a pendulum. At its highest points the kinetic energy is zero and the gravitational potential energy is at maximum. At its lowest point the kinetic energy is at maximum and is equal to the decrease of potential energy. If one (unrealistically) assumes that there is no friction or other losses, the conversion of energy between these processes would be perfect, and the pendulum would continue swinging forever.
qas: answers: text: uranium
question: Name an example of a heavy isotope?

answers: text: thorium
question: Name another example of a heavy isotope.

answers: text: nucleosynthesis
question: What is a process ultimately using the gravitational potential energy in the creation of these heavy elements before they were incorporated into the solar system and the Earth?

answers: text: chemical potential energy
question: In the case of a chemical explosion, what is transformed to kinetic energy and thermal energy in a short time?

context: Energy gives rise to weight when it is trapped in a system with zero momentum, where it can be weighed. It is also equivalent to mass, and this mass is always associated with it. Mass is also equivalent to a certain amount of energy, and likewise always appears associated with it, as described in mass-energy equivalence. The formula E = mc², derived by Albert Einstein (1905) quantifies the relationship between rest-mass and rest-energy within the concept of special relativity. In different theoretical frameworks, similar formulas were derived by J. J. Thomson (1881), Henri Poincaré (1900), Friedrich Hasenöhrl (1904) and others (see Mass-energy equivalence#History for further information).
qas: answers: text: when it is trapped in a system with zero momentum
question: When does energy give rise to weight?

answers: text: certain amount of energy
question: Mass is also equivalent to what?

answers: text: Albert Einstein
question: Who created the formula E = mc2?

answers: text: 1905
question: In what year did Einstein create E = mc2?

answers: text: E = mc²
question: What quantifies the relationship between rest-mass and rest-energy within the concept of special relativity?

context: Matter may be converted to energy (and vice versa), but mass cannot ever be destroyed; rather, mass/energy equivalence remains a constant for both the matter and the energy, during any process when they are converted into each other. However, since  is extremely large relative to ordinary human scales, the conversion of ordinary amount of matter (for example, 1 kg) to other forms of energy (such as heat, light, and other radiation) can liberate tremendous amounts of energy (~ joules = 21 megatons of TNT), as can be seen in nuclear reactors and nuclear weapons. Conversely, the mass equivalent of a unit of energy is minuscule, which is why a loss of energy (loss of mass) from most systems is difficult to measure by weight, unless the energy loss is very large. Examples of energy transformation into matter (i.e., kinetic energy into particles with rest mass) are found in high-energy nuclear physics.
qas: answers: text: energy
question: Matter may be converted to what?

answers: text: Matter
question: Energy may be converted to what?

answers: text: mass equivalent of a unit of energy is minuscule
question: Why is a loss of energy difficult to measure by weight?

answers: text: high-energy nuclear physics
question: Where are examples of energy transformation into matter found?

context: Thermodynamics divides energy transformation into two kinds: reversible processes and irreversible processes. An irreversible process is one in which energy is dissipated (spread) into empty energy states available in a volume, from which it cannot be recovered into more concentrated forms (fewer quantum states), without degradation of even more energy. A reversible process is one in which this sort of dissipation does not happen. For example, conversion of energy from one type of potential field to another, is reversible, as in the pendulum system described above. In processes where heat is generated, quantum states of lower energy, present as possible excitations in fields between atoms, act as a reservoir for part of the energy, from which it cannot be recovered, in order to be converted with 100% efficiency into other forms of energy. In this case, the energy must partly stay as heat, and cannot be completely recovered as usable energy, except at the price of an increase in some other kind of heat-like increase in disorder in quantum states, in the universe (such as an expansion of matter, or a randomisation in a crystal).
qas: answers: text: reversible processes and irreversible processes
question: Thermodynamics divides energy information into what two kinds?

answers: text: Thermodynamics
question: What divides energy transformation into two kinds reversible processes and irreversible processes?

answers: text: dissipation
question: A reversible process is one in which this does not happen.

context: As the universe evolves in time, more and more of its energy becomes trapped in irreversible states (i.e., as heat or other kinds of increases in disorder). This has been referred to as the inevitable thermodynamic heat death of the universe. In this heat death the energy of the universe does not change, but the fraction of energy which is available to do work through a heat engine, or be transformed to other usable forms of energy (through the use of generators attached to heat engines), grows less and less.
qas: answers: text: irreversible states
question: As the universe evolves in time, more and more of its energy becomes trapped in what?

answers: text: inevitable thermodynamic heat death of the universe
question: What is it referred to when more and more of energy becomes trapped in irreversible states?

answers: text: energy of the universe
question: In this heat death of energy, what does not change?

context: According to conservation of energy, energy can neither be created (produced) nor destroyed by itself. It can only be transformed. The total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. Energy is subject to a strict global conservation law; that is, whenever one measures (or calculates) the total energy of a system of particles whose interactions do not depend explicitly on time, it is found that the total energy of the system always remains constant.
qas: answers: text: conservation of energy
question: According to what, energy can neither be created nor destroyed by itself?

answers: text: total outflow of energy from the system, plus the change in the energy contained within the system
question: The total inflow of energy into a system must equal what?

answers: text: energy
question: What can neither be created nor destroyed by itself; it can only be transformed?

context: This law is a fundamental principle of physics. As shown rigorously by Noether's theorem, the conservation of energy is a mathematical consequence of translational symmetry of time, a property of most phenomena below the cosmic scale that makes them independent of their locations on the time coordinate. Put differently, yesterday, today, and tomorrow are physically indistinguishable. This is because energy is the quantity which is canonical conjugate to time. This mathematical entanglement of energy and time also results in the uncertainty principle - it is impossible to define the exact amount of energy during any definite time interval. The uncertainty principle should not be confused with energy conservation - rather it provides mathematical limits to which energy can in principle be defined and measured.
qas: answers: text: Noether's theorem
question: What shows that the conservation of energy is a mathematical consequence of translational symmetry of time?

answers: text: energy
question: What is the quantity which is canonical conjugate to time?

answers: text: the uncertainty principle
question: This mathematical entanglement of energy and time results in what?

answers: text: uncertainty principle
question: What states it is impossible to define the exact amount of energy during any definite time interval?

context: In particle physics, this inequality permits a qualitative understanding of virtual particles which carry momentum, exchange by which and with real particles, is responsible for the creation of all known fundamental forces (more accurately known as fundamental interactions). Virtual photons (which are simply lowest quantum mechanical energy state of photons) are also responsible for electrostatic interaction between electric charges (which results in Coulomb law), for spontaneous radiative decay of exited atomic and nuclear states, for the Casimir force, for van der Waals bond forces and some other observable phenomena.
qas: answers: text: Virtual photons
question: What are simply lowest quantum mechanical energy state of photons?

answers: text: Virtual photons
question: What is responsible for electrostatic interaction between electric charges?

answers: text: electrostatic interaction between electric charges
question: What results in Coulomb law?

context: Energy transfer can be considered for the special case of systems which are closed to transfers of matter. The portion of the energy which is transferred by conservative forces over a distance is measured as the work the source system does on the receiving system. The portion of the energy which does not do work during the transfer is called heat.[note 4] Energy can be transferred between systems in a variety of ways. Examples include the transmission of electromagnetic energy via photons, physical collisions which transfer kinetic energy,[note 5] and the conductive transfer of thermal energy.
qas: answers: text: Energy transfer
question: What can be considered for the special case of systems which are closed to transfers of matter?

answers: text: heat
question: The portion of energy which does not do work during the transfer is called what?

answers: text: transmission of electromagnetic energy via photons
question: Give one example of how energy can be transferred between systems?

context: The first law of thermodynamics asserts that energy (but not necessarily thermodynamic free energy) is always conserved and that heat flow is a form of energy transfer. For homogeneous systems, with a well-defined temperature and pressure, a commonly used corollary of the first law is that, for a system subject only to pressure forces and heat transfer (e.g., a cylinder-full of gas) without chemical changes, the differential change in the internal energy of the system (with a gain in energy signified by a positive quantity) is given as
qas: answers: text: first law of thermodynamics
question: What asserts that energy is always conserved and that heat flow is a form of energy transfer.

answers: text: energy
question: The first law of thermodynamics asserts that what is always conserved and that heat flow is a form of energy transfer?

answers: text: for a system subject only to pressure forces and heat transfer (e.g., a cylinder-full of gas) without chemical changes
question: What is a commonly used corollary of the first law?

context: This principle is vitally important to understanding the behaviour of a quantity closely related to energy, called entropy. Entropy is a measure of evenness of a distribution of energy between parts of a system. When an isolated system is given more degrees of freedom (i.e., given new available energy states that are the same as existing states), then total energy spreads over all available degrees equally without distinction between "new" and "old" degrees. This mathematical result is called the second law of thermodynamics.
qas: answers: text: entropy
question: What is the principle that is vitally important to understanding the behaviour of a quantity closely related to energy?

answers: text: measure of evenness of a distribution of energy between parts of a system
question: What is entropy?

answers: text: second law of thermodynamics
question: What is the mathematical result when an isolated system is given more degrees of freedom?