This is my version of a famous lithograph by M. C. Escher called Three Worlds. His print depicts a still pool in which you can see a fish below the water, leaves scattered on top of the water, and the reflection of trees in the distance: the three worlds of above, below, and on the surface. My photo, which I took just last week, is deliberately overexposed to show the same effect. You can see the reflection of a boat and some trees above the water; the duck, scattered grass, and ripples on the surface; and the weeds growing under the water. Three domains in one image.
The water surface is the equivalent of a half-silvered mirror, which reflects part of the light that hits it and lets some of the light pass through. This is how one-way mirrors work that you see all the time in the interrogation rooms in crime shows. In the brightly-lit room where the suspect is, some of the light is reflected so that it looks like a mirror, and some of the light is passed through to the other side so the observers can see what’s going on. Some of the light from the observers’ side also passes through to the interrogation room, but it’s really dark in there so there’s very little light to begin with and what gets through isn’t noticed. (On TV the observers’ room is usually much too bright because the cameras need a lot of light. If it were that bright in real life, the suspects would see the observers through the mirror.) Normal windows have the same property to a lesser extent, which is why in the daytime you see the world outside but at night you just see your room reflected back at you.
Posted in response to the WordPress photo challenge: Mirror