Though there is some research and experimentation on the subject, there is not, as of 2014, a viable way to become completely invisible. Objects and people are visible because light reflects off them and hits the viewer'... More » Science Physics Optics & Waves

Invisible fat refers to fat that cannot be easily seen and is impossible to separate from food, such as butter that has been baked into a cake or the natural oils found in nut butters. A visible fat such as olive oil may... More »

Invisible ink is a solution or compound that becomes visible upon addition of another substance and can either be made through a chemical or physical process. For example, certain "invisible" solutions only require UV li... More »

Although numerous means of becoming invisible exist in the realm of fiction, the only known way to turn invisible in the real world is by using lenses to bend light around oneself. An example of this technique is the Roc... More » Art & Literature Folklore Mythology

A convex mirror placed upside down or upright does not invert the image of its subject. A convex mirror bows outward, and therefore its focal point is behind its surface. If the focal point is at or behind the surface of... More »

The main disadvantage of microwave transmission is that microwave towers can exchange data only if they have a clear line of sight between them with no obstacles such as buildings, hills or trees in the way. Other disadv... More »

Loudness is the way in which the human ear perceives sound wave amplitude, and the larger an amplitude is, the louder the perceived sound. Amplitude refers to the magnitude of the sound wave, the pressure of its successi... More »