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Topic: Irreversibility

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	Irreversibility and Equilibrium in Biological Systems
		Irreversibility refers to a process -or a conceptualization of a process- of which we cannot trace all the intervals or trajectories.
		Irreversibility is understood as the inexistence of laws for the microscopic processes that at a specified point could originate a reversal in the trajectory of time; this is to say, that some processes cannot be traced backward without generating flanking irreversible processes.
		Irreversibility exists in natural processes externally to our knowledge, whether we imagine it or not, or if we are able to project it in mathematical models or not.
	www.biocab.org /Irreversibility.html (5004 words)

	Irreversibility
		The usual way to describe the effects of irreversible or dissipative processes at the kinetic level is to add a collision term (of one form or another) to the Liouville equation (2.3) to obtain a Boltzmann equation.
		A characteristic feature of irreversible systems is the existence of stable stationary states, which can be either the equilibrium state or a nonequilibrium steady state if the system is driven by an external agency.
		The irreversible open-system model permits a wide variety of phenomena to be described at least qualitatively without invoking a collision term.
	www.utdallas.edu /dept/ee/frensley/technical/opensyst/node8.html (1033 words)

	Irreversibility (Site not responding. Last check: 2007-10-11)
		Irreversibility is generally accepted as a principle in evolutionary biology.
		But this kind of irreversibility is a very general principle, applying to all phenomena, not only the biological.
		The proposed model furnishes a mechanistic and biological explanation for irreversibility in skeletal evolution.
	home.inreach.com /cliff_lundberg/irrevers.html (385 words)

	Environmental Economics - Irreversibility, Sustainability, and Safe Minimum Standard
		Irreversibility, sustainability, and safe minimum standard (SMS) are three terms associated with how restoration planning efforts need to approach and understand the relative complexity of ecosystems.
		Irreversibility is one significant risk to restoration practices for obvious reasons: if an altered ecosystem is in an irreversible state, then it is unlikely be restored.
		For example, an ecological state may be, in effect, irreversible at low levels of restoration effort but completely reversible at higher levels (e.g., small reductions in fisheries harvest versus moratoriums).
	www.csc.noaa.gov /coastal/economics/irreversibility.htm (3660 words)

	Anomalies and Irreversibility in Quantum Field - D. Anselmi
		A consequence is the irreversibility of the renormalization-group flow.
		The emerging irreversibility principle states that there is, in nature, a privileged spatial direction, pointing from the infinitely small to the arbitrarily large scales of magnitude.
		Time irreversibility is very much intuitive, while quantum irreversibility does not appear to be intuitive, given the non-trivial technical work that we have done to identify the quantity a and establish its main properties.
	digilander.libero.it /dionysios/pagineweb_g000000.html (6189 words)

	C:\WEBSITE\PUBLIC~1\NPT\walker.htm
		We have to build further irreversibility, partly to ensure that we don't slide back into the mud, and partly to ensure that there is solid ground from which move further towards nuclear disarmament when circumstances are more favourable.
		However, irreversibility is much less deeply embedded in the nuclear weapon states and in the three other states with weapon programmes.
		In addition to establishing this norm, the FMCT should be proclaimed as the driver of regulatory innovations in states with nuclear weapon programmes (the five and the three), and of innovations in their relations with the main organs of the non-proliferation regime.
	www.isis-online.org /publications/npt/walker.htm (3296 words)

	Irreversibility of the RG flow and the trace anomalies
		Irreversibility of the RG flow and the trace anomalies
		Secondly, I elaborate a more general axiomatic set-up where irreversibility is defined as the statement that there exist no pairs of non-trivial flows connecting interchanged UV and IR fixed points.
		In support of this, I check the axioms of irreversibility in a class of d = 3 theories where the RG flow is integrable at each order of the large N expansion.
	stacks.iop.org /0264-9381/21/29 (350 words)

	The Frontier - Entropy and the Irreversibility of Time
		Things are irreversible only in a sense that going one way is likely, and going the other way, although it is possible and is according to the laws of physics, would not happen in a million years.
		And so the apparent irreversibility of nature does not come from the irreversibility of the fundamental physical laws; it comes from the characteristic that if you start with an ordered system, and have the irregularities of nature, the bouncing of molecules, then the thing goes one way.
		The principle of irreversibility is that if things are at different temperatures and are left to themselves, as time goes on they become more and more at the same temperature, and the availability of energy is perpetually decreasing.
	members.tripod.com /~geobeck/frontier/entropy.html (1848 words)

	Irreversibility - Wikipedia, the free encyclopedia
		The phenomenon of irreversibility results from the fact that if a thermodynamic system of interacting molecules is brought from one thermodynamic state to another, the configuration or arrangement of the atoms and molecules in the system will change as a result.
		The German physicist Rudolf Clausius, in the 1850s, was the first to mathematically quantify the phenomenon of irreversibility in nature through his introduction of the concept of entropy.
		However, even if physicists claim that all processes are irreversible in a sense, the difference between reversible and irreversible events has explanatory value, if more complex systems (like living organisms, species or ecosystems) are considered.
	en.wikipedia.org /wiki/Irreversibility (408 words)

	Irreversibility and Retarded Potentials
		In contrast to mechanical phenomena, (Oeuvres 333) electromagnetic phenomena are, in general, irreversible because of radiation.
		We insert, as in Helmholtz's irreversible cycles, a speed which is hypothetically impossible to change the sense, the speed with which waves constantly move away from the bodies that generated them.
		It is from this, that electromagnetic irreversibility is derived.
	www.datasync.com /~rsf1/crit/1908e.htm (1764 words)

	Irreversibility
		Nicolis and Prigogine (1989) speak of a “universal role of irreversibility in nature” and point out that irreversibility of complex systems is not the result of “the complexity of the collective behavior of intrinsically simply objects” but rather is “due to the very structure of the dynamical systems” (pp.
		Irreversible processes that produce entropy are the creators of self-organization (Kondepudi and Prigogine, 1998).
		All of these stages are irreversible, because the human body itself is irreversible as it grows and matures from youth to old age.
	www.schuelers.com /ChaosPsyche/part_1_12.htm (726 words)

	Irreversibility
		According to Prigogine (1980) ""Irreversibility is the manifestation on a macroscopic scale of "randomness" on a microscopic scale" (p.
		Irreversible thermodynamics deals with systems that change over time, but it addresses only systems that are near to equilibrium conditions (Angrist, 1967).
		Irreversibility is the state of becoming - but it is not a universal phenomenon.
	www.schuelers.com /chaos/chaos4.htm (4670 words)

	The irreversible Universe - Equilibrium and irreversibility - part 1 of 2
		You have already seen that heat flow from a hot steak to a cold plate is an irreversible process.
		Understanding the conditions needed for equilibrium, and the irreversible processes that drive systems towards equilibrium, has deep consequences throughout the sciences.
		If the total entropy increases during a process, as it usually does, the process is irreversible - it is impossible to return to the starting point, leaving no other traces, since that would require a decrease in the total entropy, which is impossible.
	physicalworld.org /restless_universe/html/ru_3_21.html (376 words)

	Irreversibility
		In this way he gradually increases the average speed of molecules in the hot gas and decreases that in the cold, thereby in effect causing heat to flow from cold to hot.
		The ordinary phenomenon, heat passing from a hot body to a cold one, was now seen to be equivalent (though not always identical) to the transition from a partly ordered state (most fast molecules in one place, most slow molecules in another place) to a less ordered state.
		In a typical irreversible process the system passes from a nonequilibrium state (for example high temperature in one place, low in another) to an equilibrium state (uniform temperature); that is, from less probable (lower entropy) to more probable (higher entropy).
	www.math.umd.edu /~lvrmr/History/Irreversibility.html (1064 words)

	Irreversibility breeds complexity - Column 2 - ebizQ
		This is brilliant: an article by Martin Fowler in IEEE Software magazine from a few years back (via Julian On Software) really nails the issue of agility and complexity by referencing, oddly enough, a speech given by economist Enrico Zaninotto at the XP 2002 conference.
		One aspect I found particularly interesting was his [Zaninotto's] comment that irreversibility was one of the prime drivers of complexity.
		Of course, since a technical design follows the requirements stage and in turn is solidified before development begins, the irreversibilty is built into this stage as well: any changes have to go back through (potentially) several layers of approval and redesign, which impacts project schedules and contracts.
	www.ebizq.net /blogs/column2/archives/2006/05/irreversibility.php (554 words)

	A New Kind of Science: The NKS Forum - Irreversibility precedes reversibility
		One of the traditional big questions for science is how to get the time irreversibility we see in many aspects of the natural world when what are thought to be the most basic scientific theories appear to be time reversible.
		One can bend over backwards to find apparent irreversibility in underlying rules that are reversible, provided their behavior is complicated enough.
		It is "many to one"-ness of the paths (to an average) that produces irreversibility.
	forum.wolframscience.com /showthread.php?threadid=78 (2768 words)

	PhilSci Archive - Popper on irreversibility and the arrow of time
		Popper challenges the mainstream account of irreversibility, which refers to thermodynamics, by putting forward three theses: (1) There are irreversible processes of wave-production.
		However, I shall argue that Popper’s account runs into the same problem as the mainstream account: Both these accounts presuppose initial conditions of the universe that seem to be at least as improbable as anything that is explained by referring in the last resort to these initial conditions.
		Popper’s main motivation in favouring radiation over entropy increase as the source of irreversibility is that he regards a statistical theory of the arrow of time as being unacceptable.
	philsci-archive.pitt.edu /archive/00002521 (327 words)

	Irreversibility
		It should be clear immediately, then, that this microscopic invariance has little to do with the irreversibility we see on the macroscopic scale, for we cannot deal with those equations of motion directly in any event.
		A great many of the microscopic states and initial conditions will serve to define the corresponding macroscopic quantities, however, and we certainly possess initial conditions on the latter if we are studying experimentally reproducible phenomena, say.
		There is simply no way to tell if this `irreversibility' is merely mathematical or not, a point that continues to be missed [13].
	physics.uwyo.edu /~tgrandy/entropy/node6.html (574 words)

	The Temporal Resolution of Uncertainty and the Irreversibility Effect
		We define the irreversibility effect and demonstrate its importance in problems involving investment decisions under uncertainty.
		We establish several analytical and numerical results that suggest both that the effect holds more widely than generally recognized, and that an existing result (Epstein’s Theorem) giving a sufficient condition for determining whether the effect holds can be applied more widely than previously indicated, in particular to problems involving intertemporally nonseparable benefit functions.
		Urvashi Narain, W. Michael Hanemann, and Anthony Fisher, "The Temporal Resolution of Uncertainty and the Irreversibility Effect" (October 1, 2004).
	repositories.cdlib.org /are_ucb/935 (178 words)

	He's Dead, Jim: The Irreversibility of Death as a Circular Argument
		The Irreversibility of Death as a Circular Argument
		When, because of this treatment, they decline still more until they become dry bones, these dry bones are then exhibited as evidence for the irreversibility of death and the folly of believing that dead people might ever be restored to life.
		Flawed contemporary criteria are first used to attach the label "dead", and then this label is upheld as evidence of absolute irreversibility, which is a different meaning of the word entirely.
	www.alcor.org /Library/html/hesdeadjim.htm (394 words)

	Understanding of irreversibility (Site not responding. Last check: 2007-10-11)
		The thermodynamic explanation of irreversibility - does it include the microscopic view of a process, i.e.
		Irreversibility, of course, is the opposite of reversibility.
		A reversible process is one that can change direction with an infinitessimal change in conditions.
	www.physicsforums.com /showthread.php?threadid=151097 (316 words)

	Quantum Theory and Irreversibility
		The standard quantum theory is mathematically incompatible with irreversible macroscopic theories.
		An alternative irreversible quantum theory is proposed, which also provides an explanation of measurement as a physical process.
		It is based on the postulate that the physical world is governed by unitary evolution (wave propogation) punctuated by random discontinuity (particle interaction).
	www.santafe.edu /research/publications/wpabstract/199703021 (197 words)

	Temperature and Heat -- Irreversibility (Site not responding. Last check: 2007-10-11)
		Indeed, irreversibility is so common that it seems to be part of time itself.
		The energy has been shared, and while the law of the conservation of energy would allow the energy to become reconcentrated into upwards motion, this represents only one of a myriad myriad ways for the water to behave.
		The origin of irreversibility is that order turns into disorder.
	www.pa.uky.edu /~sciworks/heat/preview/irrev0a.htm (284 words)

	The myth of irreversibility - Daoud Kuttab - English Articles
		Using Gaza to debunk the myth of irreversibility is not fair.
		The key to the issue of irreversibility, of course, will be what happens in the rest of the West Bank and Jerusalem.
		But with continued determination on the part of the Palestinians, clever political management by the Palestinian leadership and the determination of the international community, what seemed impossible and irreversible a while back can become the fulfilment of the peaceful aspirations of Palestinians and of many in Israel.
	www.daoudkuttab.com /?item=the-myth-of-irreversibility (763 words)

	SSRN-Prices vs. Quantities: The Irrelevance of Irreversibility by Fridrik Baldursson, Nils-Henrik von der Fehr (Site not responding. Last check: 2007-10-11)
		We explore the efficacy of price and quantity controls in a dynamic setup in which the decisions of some agents are irreversible.
		The assumption of irreversibility is shown to improve the performance of a tax relative to that of a system of tradable quotas and significantly alter the equilibrium behavior of agents.
		We nevertheless conclude that taking into account the fact that agents' decisions may be irreversible does not lead to policy implications significantly different from those reached in a simpler model in which irreversibility is ignored.
	papers.ssrn.com /sol3/papers.cfm?abstract_id=633438 (259 words)

	Mechanics and Irreversibility
		The point of this "demon" is that, if such a demon can exist, then the second law does not hold.] Thus the irreversibility of the second law poses a great difficulty to the kinetic theory.
		The crucial point is that since there are vastly many more uniform than non-uniform distributions, the number of states which lead to uniform distributions is much greater than the number that lead to non-uniform ones.
		Thus, according to Boltzmann, the H-Theorem does not contradict the reversibility of mechanical laws, and at the same time, it can explain the irreversibility of the second law of thermo-dynamics in terms of probability.
	www.bun.kyoto-u.ac.jp /~suchii/reduction5.html (465 words)

	Irreversibility and heat generation in the computing process
		It is argued that computing machines inevitably involve devices which perform logical functions that do not have a single-valued inverse.
		This logical irreversibility is associated with physical irreversibility and requires a minimal heat generation, per machine cycle, typically of the order of kT for each irreversible function.
		Two simple, but representative, models of bistable devices are subjected to a more detailed analysis of switching kinetics to yield the relationship between speed and energy dissipation, and to estimate the effects of errors induced by thermal fluctuations.
	domino.research.ibm.com /tchjr/journalindex.nsf/c469af92ea9eceac85256bd50048567c/8a9d4b4e96887b8385256bfa0067fba2?OpenDocument (137 words)

	The irreversible Universe - Equilibrium and irreversibility - part 2 of 2
		The irreversible Universe - Equilibrium and irreversibility - part 2 of 2
		If you take two different gases and allow them to mix together in a flask that is so well insulated that no heat can be transferred to or from the flask, the entropy of the mixture turns out to be greater than the entropy of the two separate gases.
		That is why the mixing is an irreversible process.
	physicalworld.org /restless_universe/html/ru_3_22.html (356 words)

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