Editing No such thing as a free lunch (section)

==== Exceptions ====
Some exceptions from the "no free lunch" tenet have been put forward, such as the [[Sun]] and [[carbon dioxide]].<ref name="Friend">{{cite book| last = Friend| first = Tim| title = The Third Domain: The Untold Story of Archaea and the Future of Biotechnology| publisher = National Academies Press| year = 2007| page = [https://archive.org/details/thirddomainun00frie/page/21 21]| isbn = 978-0309102377| url = https://archive.org/details/thirddomainun00frie/page/21}}</ref> It was argued in particular that [[metabolism]] evolved to take advantage of the free lunch provided by the Sun, which also triggers production of vital oxygen in plants.<ref name="Friend"/>  However, these too fall short in that the viewpoint is an [[open system (systems theory)|open system]], Earth, with "free" inputs from the Sun.  When viewed from the larger system context, the Sun/Earth or Solar System, there is no net energy exchange, and still "no free lunch".<ref>{{cite news | title = Is the earth a 'closed system' with the Sun providing the sole input?| url=https://www.quora.com/Is-the-earth-a-closed-system-with-the-Sun-providing-the-sole-input| date=11 December 2013 | access-date=26 November 2016| author = Wilson, Richard}}</ref>