1. D

    distance based transparency

    Hi, Is there any optical sheet or film which is transparent to object only if the object is touching or extremely near to the sheet otherwise it acts as opaque sheet? for example, If we look through a transparent glass window of an apartment, from a distance in day light, we can’t see...
  2. timemachine2

    what is the secret to glass's transparency.

    In glass, the elements that make it up, like silicon, and sodium. Does the electron eV levels change as these elements become molecules ;D, and become solid glass. To put it another way, if silicon, sodium, and calcium atoms which have there fixed eV shell levels for electrons. If these...