"" are used in interrogation rooms etc. The wikipedia article states that:     A true one way mirror does not, and cannot, exist. Light always   passes exactly equally in both directions. However, when one side is   brightly lit and the other kept dark, the darker side becomes   difficult to see from the brightly lit side because it is masked by   the much brighter reflection of the lit side.   Which I think I understand.  What I find strange is that this surely can't be any deep principle of physics, as it's easily "violated"; you could just place a camera on one side and a TV on the other side, and it would be perfectly "see-through" from one side but not the other.  Couldn't you imagine a sort of microscopic version of the above "violation"?
I am not talking about mirrors, just a plain window made of glass like material. Would it be possible to allow light pass only in one direction but not the other?
QGIS installation error How to get video duration, dimension and size in PHP? I got 2 ghast tears after I thought I deflected a fireball back at the ghast (with my looting 3 sword).  But I was pretty close, so I might have just hit it. I'm not sure.  If I deflect a fireball with a looting sword and it kills the ghast, do I still get the looting bonus? Why I think tension should be twice the force in a tug of war How can I create a zip archive of a whole directory via terminal without hidden files? I have a project with lots of hidden folders / files in it. I want to create a zip-archive of it, but in the archive shouldn't be  any hidden folders / files. If files in a hidden folder are not hidden, they should also not be included.  I know that I can create a zip archive of a directory like this:  zip -r zipfile.zip directory   I also know that I can exclude files with the -x option, so I thought this might work:  zip -r zipfile.zip directory -x .*   It didn't work. 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I want to make some compositing with my compositing nodes but the problem is, blender won't show me the preview Image. I have a Screenshot for you guys.    The preview Image itself is enabled, but it just won't show.  Thanks for your help in advance!  -Marten bisectors of an angle in a triangle intersect at a single point - proof verification Let´s consider a general triangle ABC. Let´s draw two angle bisectors from vertices A and B.  It is obvious that these two angle bisectors intersect at a single point X. Since X lies on the angle bisector from A its distance from side b is the same as its distance from side c. As X also lies on the angle bisector from B, its distance from side c is the same as its distance from side a.  By transitivity the distance from the point X to the side b has to be the same as the distance from X to the side a. Therefore the angle bisector from C (which is the set of points equidistant from b and a) has to go through X.  It seems as a very simple argument. 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For example I have been looking into the following question  How can I plot a straight line in the JMonkey Engine library I'm trying to plot straight lines between vertices that I specify using the JMonkey Engine 3D graphics library. So for example if I was to try to plot between: (2,0,0) (-1,0,1) (0,1,1) (1,1,1) (1,4,0) Then I would get:   This is something I do (and forget how to do) relatively often and the answer is harder to find than you'd imagine ( provides everything needed to figure it out but its spread out over several posts and isn't a complete solution on its own). Therefore I want to provide a Q&amp;A for it but at present this question feels like it would fail the minimal understanding test  Questions must demonstrate a minimal understanding of the problem being solved. Tell us what you've tried to do, why it didn't work, and how it should work  Should I make up some imaginary problem? (Probably the final source code messed up a bit) Or mention in the question that I’m self answering to assuage some of the normal &quot;This is not a do your work for you site&quot; comments. Dual boot. How do I reinstall the Ubuntu partition? Very large log files, what should I do? If $a > b$, is $a^2 > b^2$? Given $a &gt; b$, where $a,b ∈ ℝ$, is it always true that $a^2 &gt; b^2$?