Sound amplification by stimulated emission of radiation phenomenon, known as the Larsen effect, is the result of a positive feedback. In general, every oscillator consists of three main parts. These are the power source or pump, the amplifier and the positive feedback leading to the output. The corresponding parts in a SASER device are the excitation or pumping mechanism, the active (amplifying) medium, and the feedback leading to acoustic radiation. Pumping can be performed, for instance, with an alternating electric field or with some mechanical vibrations of resonators. The active medium should be a material in which sound amplification can be induced. An example of a feedback
A Sound of Thunder changes in the future is a representation of the butterfly effect, and used as an example of how to consider chaos theory and the physics of time travel. A Sound of Thunder "A Sound of Thunder" is a science fiction short story by Ray Bradbury, first published in "Collier's" magazine in the June 28, 1952, issue and Bradbury's collection "The Golden Apples of the Sun" in 1953. In the year 2055, time travel has become a practical reality, and the company Time Safari Inc. offers wealthy adventurers the chance to travel back in time to hunt extinct species such as