L is for Light Amplification by Stimulated Emission of Radiation
…Otherwise known as a laser.
Lasers are a staple of science fiction, and with good reason. Lasers are beams of directed energy; they have a finesse that a projectile weapon lacks.
Some science fiction authors seem not to understand what lasers can do, and why they can do it. The principles are fairly simple, though: Photons are emitted in a coherent stream. Those photons can be focused over vast distances, called spacial coherence. Lasers have been used for many years for industrial cutting, etching, surgery, grocery store scanners, cat toys, and measuring long distances. The Apollo moon missions left scientific equipment on the moon, including reflectors. Since then, university physics students have been using lasers to measure the distance to the moon by bouncing lasers off those reflectors. (So much for ‘lasers cannot do anything because they have no range’!)
The early lasers were solid-state ruby lasers, first developed in 1960. Interestingly, the maser (Microware Stimulated Emission of Radiation) came first. Masers link satellites and transmit intercontinental calls. Other types of lasers were developed from tube technology, similar to a florescent light tube. Many modern lasers are solid state Light Emitting Diodes, LEDs. Your TV controller is probably an infrared LED laser.
In the 1980s, the US military developed bomb-pumped grasers for Project Star Wars. This was a project to develop a missile defense system, which proceeded until banned by treaty. These lasers were powerful enough to reach hundreds of thousands of kilometers and still be focused enough to blast an enemy missile out of space. They were powered by an exploding nuclear bomb. The energy was channeled in a single direction and formed a coherent beam of gamma radiation. Hence GRASER, aka: Gamma Ray Amplification by Stimulated Emission of Radiation.
Sounds a bit like science fiction, doesn’t it?
Another thing that ought to be mentioned, just because I’ve seen the term laser used extremely incorrectly a few times in works of fiction: There is no such thing as a “sound laser.” [tirade narrowly averted] By definition, a laser must be from somewhere along the electromagnetic spectrum. A laser can travel through vacuum; sound cannot. If you want to have sonic weapons in a science fiction story, that’s all well and good — they’re rather useful for some applications. But call them sonic weapons, or make up something that implies the same, and don’t call them lasers when they’re not.