There are series of events that led to the query - First what I was wondering is what happens when light falls in the "corner" of a perfect ( reflecting ) substance like the corner of a cube.
Then I was watching a video on Heisenberg's, where it said about spreading out of photons due to uncertainty as the slit is narrowed down. I wondered if it was not the opening but the whole passage is narrowed down so that the photons are not allowed to spread out, but uncertainty principle would still prevail, but how?
Thirdly, I related it with my light in corner question, there too the passage for light becomes narrower and narrower, so Heisenberg comes to play, but not allowed to spread out to "express" uncertainty in momentum. How is it going ?
Additional query - In a infinite potential well, an electron cannot tunnel. So now, I decrease the width of the tunnel ( keeping the barrier potential infinite ) to shorten the space for electron. So, again Heisenberg comes to play after a certain shortening. But again the electron is not allowed to escape the region to demonstrate uncertainty in momentum even if the width is reduced to JUST contain the electron, thus defining its position. How is these all going ? I feel I am missing something - please help me out ! So can in such circumstance the electron tunnel the infinite barrier ?