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87-474: (Redirected from Heat Death ) [REDACTED] Look up heat death in Wiktionary, the free dictionary. Heat death may refer to: Heat death of the universe , a proposed cosmological event Heat death paradox , a philosophical examination of the cosmological event Hyperthermia , injury up to and including death, from excessive heat Thermal shock ,

174-412: A cyclic process ." The second law of thermodynamics establishes the concept of entropy as a physical property of a thermodynamic system . It predicts whether processes are forbidden despite obeying the requirement of conservation of energy as expressed in the first law of thermodynamics and provides necessary criteria for spontaneous processes . For example, the first law allows the process of

261-512: A reversible or quasi-static , idealized process of transfer of energy as heat to a closed thermodynamic system of interest, (which allows the entry or exit of energy – but not transfer of matter), from an auxiliary thermodynamic system, an infinitesimal increment ( d S {\displaystyle \mathrm {d} S} ) in the entropy of the system of interest is defined to result from an infinitesimal transfer of heat ( δ Q {\displaystyle \delta Q} ) to

348-489: A very long timescale. However, if the cosmological constant is positive , the temperature will asymptote to a non-zero positive value, and the universe will approach a state of maximum entropy in which no further work is possible. The theory suggests that from the " Big Bang " through the present day, matter and dark matter in the universe are thought to have been concentrated in stars , galaxies , and galaxy clusters , and are presumed to continue to do so well into

435-563: A Universal Tendency in Nature to the Dissipation of Mechanical Energy , in which he outlined the rudiments of the second law of thermodynamics summarized by the view that mechanical motion and the energy used to create that motion will naturally tend to dissipate or run down. The ideas in this paper, in relation to their application to the age of the Sun and the dynamics of the universal operation, attracted

522-418: A crystallized structure of reduced disorder (sticking together in a certain order due to molecular attraction). The entropy of the system decreases, but the system approaches uniformity with its surroundings (category III). On the other hand, consider the refrigeration of water in a warm environment. Due to refrigeration, as heat is extracted from the water, the temperature and entropy of the water decreases, as

609-441: A cup falling off a table and breaking on the floor, as well as allowing the reverse process of the cup fragments coming back together and 'jumping' back onto the table, while the second law allows the former and denies the latter. The second law may be formulated by the observation that the entropy of isolated systems left to spontaneous evolution cannot decrease, as they always tend toward a state of thermodynamic equilibrium where

696-412: A factory. The robotic machinery requires electrical work input and instructions, but when completed, the manufactured products have less uniformity with their surroundings, or more complexity (higher order) relative to the raw materials they were made from. Thus, system entropy or disorder decreases while the tendency towards uniformity between the system and its environment is counteracted. In this example,

783-464: A full statement of the second law: Differing from Planck's just foregoing principle, this one is explicitly in terms of entropy change. Removal of matter from a system can also decrease its entropy. The second law has been shown to be equivalent to the internal energy U defined as a convex function of the other extensive properties of the system. That is, when a system is described by stating its internal energy U , an extensive variable, as

870-520: A function of its entropy S , volume V , and mol number N , i.e. U = U ( S , V , N ), then the temperature is equal to the partial derivative of the internal energy with respect to the entropy (essentially equivalent to the first TdS equation for V and N held constant): The Clausius inequality, as well as some other statements of the second law, must be re-stated to have general applicability for all forms of heat transfer, i.e. scenarios involving radiative fluxes. For example,

957-440: A general gravitational field is still not known", and "gravitational entropy is difficult to quantify". The analysis considers several possible assumptions that would be needed for estimates and suggests that the observable universe has more entropy than previously thought. This is because the analysis concludes that supermassive black holes are the largest contributor. Lee Smolin goes further: "It has long been known that gravity

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1044-476: A heat engine has an upper limit. The first rigorous definition of the second law based on the concept of entropy came from German scientist Rudolf Clausius in the 1850s and included his statement that heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time. The second law of thermodynamics allows the definition of the concept of thermodynamic temperature , but this has been formally delegated to

1131-429: A heat engine operating between any two given thermal or heat reservoirs at different temperatures. Carnot's principle was recognized by Carnot at a time when the caloric theory represented the dominant understanding of the nature of heat, before the recognition of the first law of thermodynamics , and before the mathematical expression of the concept of entropy. Interpreted in the light of the first law, Carnot's analysis

1218-436: A long time period. The hypothesis of heat death stems from the ideas of Lord Kelvin who, in the 1850s, took the theory of heat as mechanical energy loss in nature (as embodied in the first two laws of thermodynamics ) and extrapolated it to larger processes on a universal scale. This also allowed Kelvin to formulate the heat death paradox , which disproves an infinitely old universe. The idea of heat death stems from

1305-588: A nutshell, the Clausius inequality is saying that when a cycle is completed, the change in the state property S will be zero, so the entropy that was produced during the cycle must have transferred out of the system by heat transfer. The δ \delta (or đ) indicates a path dependent integration. Due to the inherent emission of radiation from all matter, most entropy flux calculations involve incident, reflected and emitted radiative fluxes. The energy and entropy of unpolarized blackbody thermal radiation,

1392-460: A perpetual motion machine had tried to circumvent the restrictions of first law of thermodynamics by extracting the massive internal energy of the environment as the power of the machine. Such a machine is called a "perpetual motion machine of the second kind". The second law declared the impossibility of such machines. Carnot's theorem (1824) is a principle that limits the maximum efficiency for any possible engine. The efficiency solely depends on

1479-639: A purely mathematical axiomatic foundation. His statement of the second law is known as the Principle of Carathéodory, which may be formulated as follows: In every neighborhood of any state S of an adiabatically enclosed system there are states inaccessible from S. With this formulation, he described the concept of adiabatic accessibility for the first time and provided the foundation for a new subfield of classical thermodynamics, often called geometrical thermodynamics . It follows from Carathéodory's principle that quantity of energy quasi-statically transferred as heat

1566-466: Is a function of state , while heat, like work, is not. For an actually possible infinitesimal process without exchange of mass with the surroundings, the second law requires that the increment in system entropy fulfills the inequality This is because a general process for this case (no mass exchange between the system and its surroundings) may include work being done on the system by its surroundings, which can have frictional or viscous effects inside

1653-561: Is a holonomic process function , in other words, δ Q = T d S {\displaystyle \delta Q=TdS} . Though it is almost customary in textbooks to say that Carathéodory's principle expresses the second law and to treat it as equivalent to the Clausius or to the Kelvin-Planck statements, such is not the case. To get all the content of the second law, Carathéodory's principle needs to be supplemented by Planck's principle, that isochoric work always increases

1740-429: Is a monotonic function of the internal energy. Nevertheless, this principle of Planck is not actually Planck's preferred statement of the second law, which is quoted above, in a previous sub-section of the present section of this present article, and relies on the concept of entropy. A statement that in a sense is complementary to Planck's principle is made by Claus Borgnakke and Richard E. Sonntag. They do not offer it as

1827-502: Is almost customary in textbooks to speak of the "Kelvin–Planck statement" of the law, as for example in the text by ter Haar and Wergeland . This version, also known as the heat engine statement , of the second law states that Max Planck stated the second law as follows. Rather like Planck's statement is that of George Uhlenbeck and G. W. Ford for irreversible phenomena . Constantin Carathéodory formulated thermodynamics on

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1914-1320: Is calculated using the spectral energy and entropy radiance expressions derived by Max Planck using equilibrium statistical mechanics, K ν = 2 h c 2 ν 3 exp ⁡ ( h ν k T ) − 1 , {\displaystyle K_{\nu }={\frac {2h}{c^{2}}}{\frac {\nu ^{3}}{\exp \left({\frac {h\nu }{kT}}\right)-1}},} L ν = 2 k ν 2 c 2 ( ( 1 + c 2 K ν 2 h ν 3 ) ln ⁡ ( 1 + c 2 K ν 2 h ν 3 ) − ( c 2 K ν 2 h ν 3 ) ln ⁡ ( c 2 K ν 2 h ν 3 ) ) {\displaystyle L_{\nu }={\frac {2k\nu ^{2}}{c^{2}}}((1+{\frac {c^{2}K_{\nu }}{2h\nu ^{3}}})\ln(1+{\frac {c^{2}K_{\nu }}{2h\nu ^{3}}})-({\frac {c^{2}K_{\nu }}{2h\nu ^{3}}})\ln({\frac {c^{2}K_{\nu }}{2h\nu ^{3}}}))} where c

2001-424: Is different from Wikidata All article disambiguation pages All disambiguation pages Heat death of the universe If the curvature of the universe is hyperbolic or flat , or if dark energy is a positive cosmological constant , the universe will continue expanding forever, and a heat death is expected to occur, with the universe cooling to approach equilibrium at a very low temperature after

2088-506: Is fully converted to work) in a cyclic fashion without any other result. Now pair it with a reversed Carnot engine as shown by the right figure. The efficiency of a normal heat engine is η and so the efficiency of the reversed heat engine is 1/ η . The net and sole effect of the combined pair of engines is to transfer heat Δ Q = Q ( 1 η − 1 ) {\textstyle \Delta Q=Q\left({\frac {1}{\eta }}-1\right)} from

2175-410: Is important for keeping the universe out of thermal equilibrium. Gravitationally bound systems have negative specific heat—that is, the velocities of their components increase when energy is removed. ... Such a system does not evolve toward a homogeneous equilibrium state. Instead it becomes increasingly structured and heterogeneous as it fragments into subsystems." This point of view is also supported by

2262-545: Is known as the Clausius statement : Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time. The statement by Clausius uses the concept of 'passage of heat'. As is usual in thermodynamic discussions, this means 'net transfer of energy as heat', and does not refer to contributory transfers one way and the other. Heat cannot spontaneously flow from cold regions to hot regions without external work being performed on

2349-411: Is neither created nor destroyed, but is simply converted from one form to another. The second law is concerned with the direction of natural processes. It asserts that a natural process runs only in one sense, and is not reversible. That is, the state of a natural system itself can be reversed, but not without increasing the entropy of the system's surroundings, that is, both the state of the system plus

2436-515: Is not in equilibrium, we cannot associate an entropy with it." Hans Adolf Buchdahl writes of "the entirely unjustifiable assumption that the universe can be treated as a closed thermodynamic system". According to Giovanni Gallavotti , "there is no universally accepted notion of entropy for systems out of equilibrium, even when in a stationary state". Discussing the question of entropy for non-equilibrium states in general, Elliott H. Lieb and Jakob Yngvason express their opinion as follows: "Despite

2523-474: Is physically equivalent to the second law of thermodynamics, and remains valid today. Some samples from his book are: In modern terms, Carnot's principle may be stated more precisely: The German scientist Rudolf Clausius laid the foundation for the second law of thermodynamics in 1850 by examining the relation between heat transfer and work. His formulation of the second law, which was published in German in 1854,

2610-802: Is possible that the universe may enter a second inflationary epoch, or assuming that the current vacuum state is a false vacuum , the vacuum may decay into a lower- energy state . It is also possible that entropy production will cease and the universe will reach heat death. It is suggested that, over vast periods of time, a spontaneous entropy decrease would eventually occur via the Poincaré recurrence theorem , thermal fluctuations , and fluctuation theorem . Through this, another universe could possibly be created by random quantum fluctuations or quantum tunnelling in roughly 10 10 10 56 {\displaystyle 10^{10^{10^{56}}}} years. Max Planck wrote that

2697-589: Is still too hot for life to arise there for thousands of years, while the Moon is already too cold. The final state, in this view, is described as one of "equilibrium" in which all motion ceases. The idea of heat death as a consequence of the laws of thermodynamics, however, was first proposed in loose terms beginning in 1851 by Lord Kelvin (William Thomson), who theorized further on the mechanical energy loss views of Sadi Carnot (1824), James Joule (1843) and Rudolf Clausius (1850). Thomson's views were then elaborated over

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2784-626: Is taken separately from that due to heat transfer by conduction and convection ( δ Q C C \delta Q_{CC} ), where the temperature is evaluated at the system boundary where the heat transfer occurs. The modified Clausius inequality, for all heat transfer scenarios, can then be expressed as, ∫ cycle ( δ Q C C T b + δ S NetRad ) ≤ 0 {\displaystyle \int _{\text{cycle}}({\frac {\delta Q_{CC}}{T_{b}}}+\delta S_{\text{NetRad}})\leq 0} In

2871-508: Is the speed of light, k is the Boltzmann constant, h is the Planck constant, ν is frequency, and the quantities K v and L v are the energy and entropy fluxes per unit frequency, area, and solid angle. In deriving this blackbody spectral entropy radiance, with the goal of deriving the blackbody energy formula, Planck postulated that the energy of a photon was quantized (partly to simplify

2958-506: The second law of thermodynamics , of which one version states that entropy tends to increase in an isolated system . From this, the hypothesis implies that if the universe lasts for a sufficient time, it will asymptotically approach a state where all energy is evenly distributed. In other words, according to this hypothesis, there is a tendency in nature towards the dissipation (energy transformation) of mechanical energy (motion) into thermal energy ; hence, by extrapolation, there exists

3045-507: The second law of thermodynamics . In Isaac Asimov's 1956 short story The Last Question , humans repeatedly wonder how the heat death of the universe can be avoided. In the 1981 Doctor Who story " Logopolis ", the Doctor realizes that the Logopolitans have created vents in the universe to expel heat build-up into other universes—"Charged Vacuum Emboitments" or "CVE"—to delay the demise of

3132-410: The zeroth law of thermodynamics . The first law of thermodynamics provides the definition of the internal energy of a thermodynamic system , and expresses its change for a closed system in terms of work and heat . It can be linked to the law of conservation of energy . Conceptually, the first law describes the fundamental principle that systems do not consume or 'use up' energy, that energy

3219-451: The Clausius statement implies the Kelvin statement. We can prove in a similar manner that the Kelvin statement implies the Clausius statement, and hence the two are equivalent. Planck offered the following proposition as derived directly from experience. This is sometimes regarded as his statement of the second law, but he regarded it as a starting point for the derivation of the second law. It

3306-535: The Entropics as a stand in for the effects of a heat death. Second law of thermodynamics The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions . A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient). Another statement is: "Not all heat can be converted into work in

3393-635: The Universe (disambiguation) All pages with titles beginning with Heat death All pages with titles containing Heat death Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Heat death . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Heat_death&oldid=1247824368 " Category : Disambiguation pages Hidden categories: Short description

3480-438: The absolute entropy of pure substances from measured heat capacity curves and entropy changes at phase transitions, i.e. by calorimetry. Introducing a set of internal variables ξ {\displaystyle \xi } to describe the deviation of a thermodynamic system from a chemical equilibrium state in physical equilibrium (with the required well-defined uniform pressure P and temperature T ), one can record

3567-466: The antagonist Kyubey reveals he is a member of an alien race who has been creating magical girls for millennia in order to harvest their energy to combat entropy and stave off the heat death of the universe. In the last act of Final Fantasy XIV: Endwalker , the player encounters an alien race known as the Ea who have lost all hope in the future and any desire to live further, all because they have learned of

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3654-530: The clock's direction, resulting in a "rejuvenating universe" – would require "a creative act or an act possessing similar power". Starting from this publication, Kelvin also introduced the heat death paradox (Kelvin's paradox), which challenged the classical concept of an infinitely old universe, since the universe has not achieved its thermodynamic equilibrium, thus further work and entropy production are still possible. The existence of stars and temperature differences can be considered an empirical proof that

3741-435: The collapse of superclusters of galaxies. Even these would evaporate over a timescale of up to 10 years. After that time, the universe enters the so-called Dark Era and is expected to consist chiefly of a dilute gas of photons and leptons . With only very diffuse matter remaining, activity in the universe will have tailed off dramatically, with extremely low energy levels and extremely long timescales. Speculatively, it

3828-637: The cooler reservoir to the hotter one, which violates the Clausius statement. This is a consequence of the first law of thermodynamics , as for the total system's energy to remain the same; Input + Output = 0 ⟹ ( Q + Q c ) − Q η = 0 {\textstyle {\text{Input}}+{\text{Output}}=0\implies (Q+Q_{c})-{\frac {Q}{\eta }}=0} , so therefore Q c = Q ( 1 η − 1 ) {\textstyle Q_{c}=Q\left({\frac {1}{\eta }}-1\right)} , where (1)

3915-451: The destruction of equipment by overheating A Supernova , heat death of a star, along with the death of the star itself In arts [ edit ] The Heat Death of the Universe , 2003 album by punk band Off Minor "The Heat Death of the Universe", a short story by Pamela Zoline See also [ edit ] [REDACTED] Search for "heat death" on Misplaced Pages. Dead Heat (disambiguation) Heat Death of

4002-444: The entropy flux of NBR emission is farther removed from the conduction and convection q / T result, than that for BR emission. This observation is consistent with Max Planck's blackbody radiation energy and entropy formulas and is consistent with the fact that blackbody radiation emission represents the maximum emission of entropy for all materials with the same temperature, as well as the maximum entropy emission for all radiation with

4089-411: The entropy is highest at the given internal energy. An increase in the combined entropy of system and surroundings accounts for the irreversibility of natural processes, often referred to in the concept of the arrow of time . Historically, the second law was an empirical finding that was accepted as an axiom of thermodynamic theory . Statistical mechanics provides a microscopic explanation of

4176-459: The entropy of the system's surroundings. If an isolated system containing distinct subsystems is held initially in internal thermodynamic equilibrium by internal partitioning by impermeable walls between the subsystems, and then some operation makes the walls more permeable, then the system spontaneously evolves to reach a final new internal thermodynamic equilibrium , and its total entropy, S {\displaystyle S} , increases. In

4263-411: The entropy spontaneously decreases by means of energy and entropy transfer. When thermodynamic constraints are not present, spontaneously energy or mass, as well as accompanying entropy, may be transferred out of a system in a progress to reach external equilibrium or uniformity in intensive properties of the system with its surroundings. This occurs spontaneously because the energy or mass transferred from

4350-433: The equality The second term represents work of internal variables that can be perturbed by external influences, but the system cannot perform any positive work via internal variables. This statement introduces the impossibility of the reversion of evolution of the thermodynamic system in time and can be considered as a formulation of the second principle of thermodynamics – the formulation, which is, of course, equivalent to

4437-528: The eventual heat death of the universe and see everything else as pointless due to its probable inevitability. The overarching plot of the Xeelee Sequence concerns the Photino Birds' efforts to accelerate the heat death of the universe by accelerating the rate at which stars become white dwarves. The 2019 hit indie video game Outer Wilds has several themes grappling with the idea of the heat death of

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4524-413: The fact of a recent experimental discovery of a stable non-equilibrium steady state in a relatively simple closed system. It should be expected that an isolated system fragmented into subsystems does not necessarily come to thermodynamic equilibrium and remain in non-equilibrium steady state. Entropy will be transmitted from one subsystem to another, but its production will be zero, which does not contradict

4611-472: The fact that most physicists believe in such a nonequilibrium entropy, it has so far proved impossible to define it in a clearly satisfactory way." In Peter Landsberg's opinion: "The third misconception is that thermodynamics, and in particular, the concept of entropy, can without further enquiry be applied to the whole universe. ... These questions have a certain fascination, but the answers are speculations." A 2010 analysis of entropy states, "The entropy of

4698-433: The factory from the local electric grid. In addition, humans may directly play, in whole or in part, the role that the robotic machinery plays in manufacturing. In this case, instructions may be involved, but intelligence is either directly responsible, or indirectly responsible, for the direction or application of work in such a way as to counteract the tendency towards disorder and uniformity. There are also situations where

4785-440: The final state of the universe depend on the assumptions made about its ultimate fate, and these assumptions have varied considerably over the late 20th century and early 21st century. In a hypothesized "open" or "flat" universe that continues expanding indefinitely, either a heat death or a Big Rip is expected to eventually occur. If the cosmological constant is zero, the universe will approach absolute zero temperature over

4872-404: The flow of heat in steam engines (1824). The centerpiece of that analysis, now known as a Carnot engine , is an ideal heat engine fictively operated in the limiting mode of extreme slowness known as quasi-static, so that the heat and work transfers are between subsystems that are always in their own internal states of thermodynamic equilibrium . It represents the theoretical maximum efficiency of

4959-451: The formulation of the principle in terms of entropy. The zeroth law of thermodynamics in its usual short statement allows recognition that two bodies in a relation of thermal equilibrium have the same temperature, especially that a test body has the same temperature as a reference thermometric body. For a body in thermal equilibrium with another, there are indefinitely many empirical temperature scales, in general respectively depending on

5046-410: The four combinations of either entropy (S) up or down, and uniformity (Y) – between system and its environment – up or down. This 'special' category of processes, category IV, is characterized by movement in the direction of low disorder and low uniformity, counteracting the second law tendency towards uniformity and disorder. The second law can be conceptually stated as follows: Matter and energy have

5133-446: The future. Therefore, the universe is not in thermodynamic equilibrium , and objects can do physical work. The decay time for a supermassive black hole of roughly 1 galaxy mass (10   solar masses ) because of Hawking radiation is in the order of 10  years, so entropy can be produced until at least that time. Some large black holes in the universe are predicted to continue to grow up to perhaps 10 M ☉ during

5220-406: The instructions, as well as the source of work may be internal or external to the system, and they may or may not cross the system boundary. To illustrate, the instructions may be pre-coded and the electrical work may be stored in an energy storage system on-site. Alternatively, the control of the machinery may be by remote operation over a communications network, while the electric work is supplied to

5307-536: The integrand (đQ/T) of the Clausius expression applies to heat conduction and convection, and the case of ideal infinitesimal blackbody radiation (BR) transfer, but does not apply to most radiative transfer scenarios and in some cases has no physical meaning whatsoever. Consequently, the Clausius inequality was re-stated so that it is applicable to cycles with processes involving any form of heat transfer. The entropy transfer with radiative fluxes ( δ S NetRad \delta S_{\text{NetRad}} )

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5394-402: The internal energy of a closed system that was initially in its own internal thermodynamic equilibrium. In 1926, Max Planck wrote an important paper on the basics of thermodynamics. He indicated the principle This formulation does not mention heat and does not mention temperature, nor even entropy, and does not necessarily implicitly rely on those concepts, but it implies the content of

5481-456: The law in terms of probability distributions of the states of large assemblies of atoms or molecules . The second law has been expressed in many ways. Its first formulation, which preceded the proper definition of entropy and was based on caloric theory , is Carnot's theorem , formulated by the French scientist Sadi Carnot , who in 1824 showed that the efficiency of conversion of heat to work in

5568-533: The likes of William Rankine and Hermann von Helmholtz. The three of them were said to have exchanged ideas on this subject. In 1862, Thomson published "On the age of the Sun's heat", an article in which he reiterated his fundamental beliefs in the indestructibility of energy (the first law ) and the universal dissipation of energy (the second law), leading to diffusion of heat, cessation of useful motion ( work ), and exhaustion of potential energy , "lost irrecoverably" through

5655-430: The material universe, while clarifying his view of the consequences for the universe as a whole. Thomson wrote: The result would inevitably be a state of universal rest and death, if the universe were finite and left to obey existing laws. But it is impossible to conceive a limit to the extent of matter in the universe; and therefore science points rather to an endless progress, through an endless space, of action involving

5742-460: The mathematics), thereby starting quantum theory. A non-equilibrium statistical mechanics approach has also been used to obtain the same result as Planck, indicating it has wider significance and represents a non-equilibrium entropy. A plot of K v versus frequency (v) for various values of temperature ( T) gives a family of blackbody radiation energy spectra, and likewise for the entropy spectra. For non-blackbody radiation (NBR) emission fluxes,

5829-555: The next decade by Hermann von Helmholtz and William Rankine . The idea of the heat death of the universe derives from discussion of the application of the first two laws of thermodynamics to universal processes. Specifically, in 1851, Lord Kelvin outlined the view, as based on recent experiments on the dynamical theory of heat : "heat is not a substance, but a dynamical form of mechanical effect, we perceive that there must be an equivalence between mechanical work and heat, as between cause and effect." In 1852, Thomson published On

5916-452: The phrase "entropy of the universe" has no meaning because it admits of no accurate definition. In 2008, Walter Grandy wrote: "It is rather presumptuous to speak of the entropy of a universe about which we still understand so little, and we wonder how one might define thermodynamic entropy for a universe and its major constituents that have never been in equilibrium in their entire existence." According to László Tisza , "If an isolated system

6003-418: The properties of a particular reference thermometric body. The second law allows a distinguished temperature scale, which defines an absolute, thermodynamic temperature , independent of the properties of any particular reference thermometric body. The second law of thermodynamics may be expressed in many specific ways, the most prominent classical statements being the statement by Rudolf Clausius (1854),

6090-477: The same energy radiance. Second law analysis is valuable in scientific and engineering analysis in that it provides a number of benefits over energy analysis alone, including the basis for determining energy quality (exergy content ), understanding fundamental physical phenomena, and improving performance evaluation and optimization. As a result, a conceptual statement of the principle is very useful in engineering analysis. Thermodynamic systems can be categorized by

6177-404: The second law. A closely related statement is that "Frictional pressure never does positive work." Planck wrote: "The production of heat by friction is irreversible." Not mentioning entropy, this principle of Planck is stated in physical terms. It is very closely related to the Kelvin statement given just above. It is relevant that for a system at constant volume and mole numbers , the entropy

6264-399: The sign convention of heat is used in which heat entering into (leaving from) an engine is positive (negative) and (2) Q η {\displaystyle {\frac {Q}{\eta }}} is obtained by the definition of efficiency of the engine when the engine operation is not reversed. Thus a violation of the Kelvin statement implies a violation of the Clausius statement, i.e.

6351-404: The spectral entropy radiance L v is found by substituting K v spectral energy radiance data into the L v expression (noting that emitted and reflected entropy fluxes are, in general, not independent). For the emission of NBR, including graybody radiation (GR), the resultant emitted entropy flux, or radiance L , has a higher ratio of entropy-to-energy ( L/K ), than that of BR. That is,

6438-458: The state of its surroundings cannot be together, fully reversed, without implying the destruction of entropy. For example, when a path for conduction or radiation is made available, heat always flows spontaneously from a hotter to a colder body. Such phenomena are accounted for in terms of entropy change . A heat pump can reverse this heat flow, but the reversal process and the original process, both cause entropy production, thereby increasing

6525-461: The statement by Lord Kelvin (1851), and the statement in axiomatic thermodynamics by Constantin Carathéodory (1909). These statements cast the law in general physical terms citing the impossibility of certain processes. The Clausius and the Kelvin statements have been shown to be equivalent. The historical origin of the second law of thermodynamics was in Sadi Carnot 's theoretical analysis of

6612-455: The system may become more ordered or complex, by the combination of two things, a work or exergy source and some form of instruction or intelligence. Where 'exergy' is the thermal, mechanical, electric or chemical work potential of an energy source or flow, and 'instruction or intelligence', although subjective, is in the context of the set of category IV processes. Consider a category IV example of robotic manufacturing and assembly of vehicles in

6699-427: The system moves further away from uniformity with its warm surroundings or environment (category IV). The main point, take-away, is that refrigeration not only requires a source of work, it requires designed equipment, as well as pre-coded or direct operational intelligence or instructions to achieve the desired refrigeration effect. Before the establishment of the second law, many people who were interested in inventing

6786-464: The system of interest, divided by the common thermodynamic temperature ( T ) {\displaystyle (T)} of the system of interest and the auxiliary thermodynamic system: Different notations are used for an infinitesimal amount of heat ( δ ) {\displaystyle (\delta )} and infinitesimal change of entropy ( d ) {\displaystyle (\mathrm {d} )} because entropy

6873-504: The system to its surroundings results in a higher entropy in the surroundings, that is, it results in higher overall entropy of the system plus its surroundings. Note that this transfer of entropy requires dis-equilibrium in properties, such as a temperature difference. One example of this is the cooling crystallization of water that can occur when the system's surroundings are below freezing temperatures. Unconstrained heat transfer can spontaneously occur, leading to water molecules freezing into

6960-411: The system, because a chemical reaction may be in progress, or because heat transfer actually occurs only irreversibly, driven by a finite difference between the system temperature ( T ) and the temperature of the surroundings ( T surr ). The equality still applies for pure heat flow (only heat flow, no change in chemical composition and mass), which is the basis of the accurate determination of

7047-417: The system, which is evident from ordinary experience of refrigeration , for example. In a refrigerator, heat is transferred from cold to hot, but only when forced by an external agent, the refrigeration system. Lord Kelvin expressed the second law in several wordings. Suppose there is an engine violating the Kelvin statement: i.e., one that drains heat and converts it completely into work (the drained heat

7134-404: The tendency to reach a state of uniformity or internal and external equilibrium, a state of maximum disorder (entropy). Real non-equilibrium processes always produce entropy, causing increased disorder in the universe, while idealized reversible processes produce no entropy and no process is known to exist that destroys entropy. The tendency of a system to approach uniformity may be counteracted, and

7221-426: The transformation of potential energy into palpable motion and hence into heat , than to a single finite mechanism, running down like a clock, and stopping for ever. The clock's example shows how Kelvin was unsure whether the universe would eventually achieve thermodynamic equilibrium . Thompson later speculated that restoring the dissipated energy in " vis viva " and then usable work – and therefore revert

7308-411: The universe is not infinitely old. In the years to follow both Thomson's 1852 and the 1862 papers, Helmholtz and Rankine both credited Thomson with the idea, along with his paradox, but read further into his papers by publishing views stating that Thomson argued that the universe will end in a "heat death" (Helmholtz), which will be the "end of all physical phenomena" (Rankine). Proposals about

7395-425: The universe, and the theory that the universe is a cycle of big bangs once the previous one has experienced a heat death. In Singularity Immemorial — the 7th main story event of a mobile game Girls' Frontline: Neural Cloud — the plot is about a virtual sector made to simulate space exploration and the threat of the heat death of the universe. The simulation uses an imitation of Neural Cloud's virus entities known as

7482-483: The universe. The Doctor unwittingly travelled through such a vent in " Full Circle ". In the 1995 computer game I Have No Mouth, and I Must Scream , based on the Harlan Ellison short story of the same name , it is stated that AM, the malevolent supercomputer, will survive the heat death of the universe and continue torturing its immortal victims to eternity. In the 2011 anime series Puella Magi Madoka Magica ,

7569-602: The view that, in time, the mechanical movement of the universe will run down as work is converted to heat because of the second law. The conjecture that all bodies in the universe cool off, eventually becoming too cold to support life, seems to have been first put forward by the French astronomer Jean Sylvain Bailly in 1777 in his writings on the history of astronomy and in the ensuing correspondence with Voltaire . In Bailly's view, all planets have an internal heat and are now at some particular stage of cooling. Jupiter , for instance,

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