Another related thought experiment Consider the focusing of sunlight by a simple parabolic reflector. Why doesn't that constitute a violation of the 2nd law of thermodynamics which (according to one of the many equivalents formulations) says heat cannot flow from a cold to hot region without an input of work. It is because the reflector does work by changing the path of light photons. A reflector attached to the ground does not appear to do any work because the bulk of the Earth pushes back too.
However imagine a number of parabolic reflectors assembled in a spherical arrangement suspended inside a translucent bubble so the light is uniform in all directions. Each reflector focuses light but collectively the 2nd law is violated because they do not appear to do any work since they all push against each other and so do not move. Harry On Thu, Oct 9, 2014 at 5:10 PM, David L. Babcock <[email protected]> wrote: > Thank you. Also, Noted that the 2nd law is not violated. > > Ol' Bab > > > On 10/7/2014 1:34 PM, Ian Walker wrote: > > Hi David > > I did a search for "good-bye-second-law-of-thermodynamics" > > It came up in google with this > > http://www.laserfocusworld.com/articles/2014/09/good-bye-second-law-of-thermodynamics.html > > I clicked on the link in google and it took me to the page that I quote > the first few lines of: > > " > Home <http://www.laserfocusworld.com/content/lfw/en/index.html> > Good-bye second law of thermodynamics? > Good-bye second law of thermodynamics? > 09/02/2014 > By John Wallace > <http://www.laserfocusworld.com/content/lfw/en/authors/john-wallace.html> > Senior Editor > > I was quite happy last week to post a news item about a colorless > transparent luminescent solar concentrator developed at Michigan State > University > <http://www.laserfocusworld.com/articles/2014/08/solar-collector-is-transparent-colorless-doesn-t-block-the-view.html> > (East > Lansing, MI), as I have had a long-term fascination with luminescent solar > concentrators. So why am I so fascinated by such devices? > > One reason is that at first glance they seem to violate the second law of > thermodynamics > <http://www.laserfocusworld.com/articles/print/volume-49/issue-06/features/chillers-and-coolers--breakthrough-of-optical-refrigeration--las.html>, > which says that the entropy of any isolated system never decreases. In the > field of optics, the second law sorta translates in a hand-waving way to > the fact that the étendue (solid angle multiplied by beam cross-section) of > a light beam can never decrease: for example, one can't focus a low-quality > laser beam to a spot as small as that that can be produced by a > high-quality laser beam (given the same lens used for both, with lens pupil > optimally filled)..." > > Kind Regards walker > > On 7 October 2014 18:52, David L. Babcock <[email protected]> wrote: > >> Exact link not found. On inspection, no such article found in their many >> lists. >> Pulled? >> >> Ol' Bab >> >> >> >> On 10/5/2014 9:33 PM, Jones Beene wrote: >> >>> Every week it seems, there is a new assault around the edges of the 2nd >>> Generalization of Thermodynamics... >>> >>> >>> http://www.laserfocusworld.com/articles/2014/09/good-bye-second-law-of-therm >>> odynamics.html >>> >>> >> >> --- >> This email is free from viruses and malware because avast! Antivirus >> protection is active. >> http://www.avast.com >> >> > > > > ------------------------------ > <http://www.avast.com/> > > This email is free from viruses and malware because avast! Antivirus > <http://www.avast.com/> protection is active. > >
