Talk:Isolated system

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IncipitEdit

I deleted the paragraph dealing with background microwave radiation. I think the statement that it permeates every object is mistaken. While the radiation may be ubiquitous, it's still just microwave radiation, and not at all difficult to shield against with any conductive barrier. It might be difficult to build an isolated system without an initial contribution of energy from this background radiation, but that is also not a requirement for an isolated system. As long as it's isolated now, it doesn't matter if some of the energy originally came from an outside source.

I also realize a metal barrier would eventually heat up to 2.7K from the background radiation and emit its own blackbody radiation. In that sense, one could argue that the background radiation has "permeated through the barrier" once equilibrium is achieved, but that time can be made arbitrarily long by using thicker or successive insulating layers. So I agree it's impossible to build a permanently isolated system, but that point has already been addressed in the previous paragraph. It seems pretty clear that like many concepts in science, the isolated system is just a model of an ideal limiting case, and the bulk of the article need not be spent on reasons why the limit can never trully be attained in real life.


The final paragraph is just one opinion in a hotly debated philosophical area, and is probably not the right way to look at it. See the book "Time's Arrow and Archimedies' Point" by Huw Price. 139.184.30.18 15:50, 31 July 2007 (UTC)

MisleadingEdit

No sources are cited and the page should differentiate between the use of the term in mathematics/physics from the uses in other areas. This is important to prevent misleading analogies and metaphors, and hence the misinterpretation of science. --Kenneth M Burke 01:28, 25 August 2007 (UTC)

Added "In the natural sciences" in the introduction which should no be misleading any more. The lack of sources, cition and or differentiation doesn't make this article misleading - Mdd 16:16, 25 August 2007 (UTC)
See Talk:Open system (system theory) --Kenneth M Burke 16:27, 25 August 2007 (UTC)
I repeat. This article is not misleading any more. - Mdd 18:45, 25 August 2007 (UTC)

Incorrect statement re effect of gravityEdit

The statement claiming an isolated system is not affected by gravity is simply incorrect. There is significant gravity everywhere in the Solar System and of course it applies a force to the mass of molecules in any isolated system. The force of gravity must be taken into account, for example, when determining the state of maximum entropy that the Second Law of Thermodynamics tells us will evolve in an isolated system. That law in fact only applies to an isolated system. This is where Clausius was in error because he ignored the effect on entropy of gravity acting on molecules at different heights. As a consequence, the Clausius statement (when applied to heat transfer that is other than by radiation) is not correct in a vertical plane in a gravitational field. So the statement made in the article is false and prone to lead to incorrect conclusions if applied in any vertically oriented isolated system.


Is the universe an isolated system?Edit

Is it clear that the universe is an isolated system? Of course, one could define it as such, but that misses the point. The observable universe certainly is not isolated since the boundary of the observable universe is expanding at the speed of light. Our four dimensional universe may not be closed to collisions with other four dimensional branes in a higher dimensional universe. We have recently learned that space can be created by dark energy. Is it unthinkable that energy, fields and particles might be as well. This was a part of Hoyle's Steady State theory that was largely defeated by evidence of the Big Bang. However, it is not clear that Big Bang and aspects of Steady State might not both be true. I cannot accept the notion of an isolated universe as an axiomatic definition without clarification of what we mean by the universe. And that, it seems to me, is part of the yet unfinished job of physics.Lou (talk) 21:07, 15 January 2008 (UTC)

 
"(...) The observable universe certainly is not isolated since the boundary of the observable universe is expanding at the speed of light. (...)"(User Lou 15th January 2008 - Isolated system talk page)
Very nice point Lou. I guess Unsolved_problems_in_physics#Other_problems deserves your observation about the fact that that the universe is NOT CLEARLY an isolated system.
And, by the way, anyone has a clue of how come that the "closed system" article has a section for:
  1. thermodynamics (Thermodynamic system), one for
  2. classical mechanics, one for
  3. computing (closed source software) and one for
  4. engineering
while this article has NO sections at all?
Duh? Maurice Carbonaro (talk) 08:35, 7 August 2012 (UTC)

Added a line that says that the universe is often considered to be an isolated system, which seems to agree with literature. Left intentionally vague, as there is clearly some disagreement about this statement. --Tim Alphabeaver (talk) 00:09, 30 January 2020 (UTC)

 
Hawking radiation could account for not considering the "universe as a whole" like a closed system...
What about black holes evaporation?
Also, the universe can NOT be considered a closed system because of Hawking radiation... this means that there is constantly "something" "somewhere" in the universe close to one of the myriad of black holes dwelling in the universe that edmits and or absorbs energy/mass... Or not? Please take a peek at the Event horizon article before posting or sending me a private e-mail. Thanks. Maurice Carbonaro (talk) 18:33, 6 November 2012 (UTC)

External linksEdit

The connection between all the (functioning) external links and this topic seem weak, so I have removed them. They are:

They do mention the term "isolated system" but not in much detail. Based on my reading of Wikipedia:External links these links are too indirect to be included. Others may have different interpretations however, hence posting here. David Hollman (Talk) 21:28, 2 September 2010 (UTC)

This page has an average of 300 viewers per dayEdit

 
Isolated systems are mostly studied in theoretical physics.

Hi all,

I noticed that this particular article has an average of 300 viewers per day and ... growing!
Editors are more than welcome to participate in this article page talk, especially in the "Isolated system: "Is the universe an -isolated system-"?" talk/article/chapter.
Thank you.

Maurice Carbonaro (talk) 19:31, 7 November 2012 (UTC)

All the more reason for you not to make edits about things you clearly do not understand. — Arthur Rubin (talk) 13:45, 8 November 2012 (UTC)

Merge into Closed Systems?Edit

Shouldn't this just be merged into, or deleted in favor of, "Closed System"? They're essentially synonyms. The main differences are that this article is a very miscellaneous stub, and that it contains this sort of weakly-supported distinction between "closed" and "isolated" (which is used in a few physical chemistry texts, I guess, but hardly a generally-accepted distinction, is it?). In contrast, Closed Systems says, more plausibly, "The specification of what types of transfers are excluded, is different in different contexts." Orbst (talk) 19:13, 30 April 2014 (UTC)

I would think it better to retain this article. I think it goes too far to say that 'isolated system' and 'closed system' are essentially synonyms. I think most thermodynamic texts nowadays distinguish between isolated and closed systems as is done in this article. There are a few exceptions, notably Callen, and Kittel & Kroemer.Chjoaygame (talk) 22:08, 30 April 2014 (UTC)

Walls or boundaries?Edit

In the article "walls" is used 11 times... maybe "boundaries" would be more appropriate?   M aurice   Carbonaro  10:00, 29 October 2015 (UTC)

Thank you for raising this question. Some time ago I reported on a related talk page a survey of reliable sources on thermodynamics to answer this question. The result was by far the more customary usage, in thermodynamics texts, of the term 'walls', not 'boundaries'. Walls have important physical properties, such as selective permeability and adiabaticity. Boundaries have a more purely mathematical flavor. One finds 'boundaries' occasionally in reliable thermodynamic texts.Chjoaygame (talk) 14:33, 29 October 2015 (UTC)