395. Is all light other than lasers incoherent?
Yes, in the sense that the only way to create coherent light is through the use of laser amplification. While it is possible to create coherent radio waves by synchronizing the motion of many charged particles, it is extremely difficult to synchronize the charged particles that emit visible light. (The one exception to this statement is a free electron laser, an exotic device that uses the beam of electrons from a particle accelerator to produce coherent light.) In general, you must use stimulated emission if you want to create coherent light.