Heat death of the universe
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The heat death of the universe (also known as the Big Chill or Big Freeze)[1][2] is a hypothesis on the ultimate fate of the universe, which suggests the universe will evolve to a state of no thermodynamic free energy, and will therefore be unable to sustain processes that increase entropy. Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium.
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,[3] with the universe cooling to approach equilibrium at a very low temperature after a long time period.
The hypothesis of heat death stems from the ideas of
Origins of the idea
The idea of heat death stems from the
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, 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.[5]
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
History
The idea of the heat death of the universe derives from discussion of the application of the first two
In 1852, Thomson published On 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.[8] The ideas in this paper, in relation to their application to the age of the Sun and the dynamics of the universal operation, attracted the likes of William Rankine and Hermann von Helmholtz. The three of them were said to have exchanged ideas on this subject.[6] 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 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 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.[4]
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 the clock's direction, resulting in a "rejuvenating universe" – would require "a creative act or an act possessing similar power".[9][10] Starting from this publication, Kelvin also introduced the heat death paradox (Kelvin's paradox), which disproves 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 the universe is not infinitely old.[11][4]
In the years to follow both Thomson's 1852 and the 1862 papers,
Current status
Proposals about 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.[3][13] If the cosmological constant is zero, the universe will approach absolute zero temperature over 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.[14]
Time frame for heat death
The theory suggests that from the "
It is suggested that, over vast periods of time, a spontaneous entropy decrease would eventually occur via the Poincaré recurrence theorem,[18] thermal fluctuations,[19][20][21] and fluctuation theorem.[22][23] Through this, another universe could possibly be created by random quantum fluctuations or quantum tunnelling in roughly years.[24]
Opposing views
Max Planck wrote that the phrase "entropy of the universe" has no meaning because it admits of no accurate definition.[25][26] 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."[27] According to László Tisza, "If an isolated system is not in equilibrium, we cannot associate an entropy with it."[28] Hans Adolf Buchdahl writes of "the entirely unjustifiable assumption that the universe can be treated as a closed thermodynamic system".[29] According to Giovanni Gallavotti, "there is no universally accepted notion of entropy for systems out of equilibrium, even when in a stationary state".[30] Discussing the question of entropy for non-equilibrium states in general, Elliott H. Lieb and Jakob Yngvason express their opinion as follows: "Despite 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."[31] 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."[32]
A 2010 analysis of entropy states, "The entropy of 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.[33] Lee Smolin goes further: "It has long been known that gravity 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."[34] This point of view is also supported by the fact of a recent[when?] 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 the second law of thermodynamics.[35][36]
In popular culture
This section includes a improve this section by introducing more precise citations. (November 2023) ) |
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 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
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 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 the universe, and the theory that the universe is a cycle of big bangs once the previous one has experienced a heat death.
See also
- Arrow of time – Concept in physics of one-way time
- Big Bang – Physical theory describing the expansion of the universe
- Big Bounce – Model for the origin of the universe
- Big Crunch – Theoretical scenario for the ultimate fate of the universe
- Big Rip – Cosmological model
- Chronology of the universe – History and future of the universe
- Cyclic model – Cosmological models involving indefinite, self-sustaining cycles
- Entropy (arrow of time) – Use of the second law of thermodynamics to distinguish past from future
- Fluctuation theorem
- Graphical timeline from Big Bang to Heat Death – Visual representation of the universe's past, present, and future
- Heat death paradox – Paradox relating to fate of universe
- The Last Question – Science-fiction short story by Isaac Asimov
- Timeline of the far future – Scientific projections regarding the far future
- Orders of magnitude (time) – Decimal quantities of a base unit of time
- Thermodynamic temperature – Measure of absolute temperature
References
- ^ WMAP – Fate of the Universe, WMAP's Universe, NASA. Accessed online July 17, 2008.
- ISBN 978-1-4169-3860-6.
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- ^ a b c Thomson, Sir William (5 March 1862). "On the Age of the Sun's Heat". Macmillan's Magazine. Vol. 5. pp. 388–93.
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- Transactions of the Royal Society of Edinburgh, March 1851, and Philosophical Magazine IV, 1852. This version from Mathematical and Physical Papers, vol. i, art. XLVIII, pp. 174.
- Proceedings of the Royal Society of Edinburgh for 19 April 1852, also Philosophical Magazine, Oct. 1852. This version from Mathematical and Physical Papers, vol. i, art. 59, pp. 511.
- ^ Harold I. Sharlin (13 December 2019). "William Thomson, Baron Kelvin". Encyclopædia Britannica. Retrieved 24 January 2020.
- ^ Otis, Laura (2002). "Literature and Science in the Nineteenth Century: An Anthology". OUP Oxford. Vol. 1. pp. 60–67.
- ^ Laws of Thermodynamics Thompson and Clausius, Oxford University Press, 2015.
- ^ "Physics Chronology". Archived from the original on 22 May 2011.
- ^ Consolmagno, Guy (2008-05-08). "Heaven or Heat Death?". Thinking Faith. Archived from the original on 2023-11-16. Retrieved 2008-10-06.
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Since we have assumed a maximum scale of gravitational binding—for instance, superclusters of galaxies—black hole formation eventually comes to an end in our model, with masses of up to 1014M☉ ... the timescale for black holes to radiate away all their energy ranges ... to 10106 years for black holes of up to 1014M☉
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The importance of Planck's Vorlesungen über Thermodynamik (Planck 1897) can hardly be [over]estimated. The book has gone through 11 editions, from 1897 until 1964, and still remains the most authoritative exposition of classical thermodynamics.
- ^ Planck, Max (1903). Treatise on Thermodynamics. Translated by Ogg, Alexander. London: Longmans, Green. p. 101.
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