The Indistinguishable Flame
The Indistinguishable Flame by Jonathan Troutman
In this photo a wine glass acts as a biconcave converging lens. The flame is actually several inches behind the glass but the image produced seems to be magnified inside of the glass. This is caused by refraction due to the curved surface of the wine glass. When light enters a material that has a higher index of refraction it slows down. Water has a higher index of refraction than air does and the result is that light waves are bent out toward the edges of the cup magnifying the image.