"If aliens
visit us, the outcome would be much as when Columbus landed in
America, which didn't turn out well for the Native Americans." Stephen Hawking
By applying the boundary conditions for electromagnetic waves
striking the boundary between two media it can be shown that the
intensity of the reflected and refracted waves depend on the
polarisation of the incident wave.
In particular, for unpolarised light incident on the boundary
at a specific angle, θp , the reflected light
contains only one polarisation. When this occurs the
reflected and refracted light rays are at 900 to each
other,
For light incident on water (from air) we find that θp=
530. Thus, at this angle the light
reflected from the surface is (linearly)
polarised. If this reflected wave is viewed with
polarised sunglasses (which block this particular
polarisation), no reflective glare is observed -
allowing the observer to see clearly underwater.
"Outside
of a dog, a book is a man's best friend. Inside of a dog
it's too dark to read." Groucho Marx
