Talk:Isolated system
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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)
[edit] Misleading
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)
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- 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)
[edit] Is the universe an isolated system?
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)
