In our everyday lives, we rarely get to see anything that could be described in nano-scale terms, but soap bubbles and drops of oil that have spread over a puddle of water are among the few examples. Depending on light conditions and angle, both of these often appear rainbow-colored, at which times they are membranes of several hundred nanometers in thickness. And in nano-scale terms, a human hair is incredibly thick, with a diameter of about 50 µm, or 50,000 nm.