Although scientists have been familiar with the principle of Occam's razor for centuries, it became more widely known to the general public after the movie Contact came out in 1997. The movie, based on a novel written by Carl Sagan and starring Jodie Foster as SETI scientist Dr. Ellie Arroway, involves the first confirmed communication received on Earth by extraterrestrial intelligence.
The communication is eventually discovered to be a diagram to build a transporter, which Ellie uses to travel through a series of wormholes to visit with one of the aliens who made the transport possible, in a first step toward interstellar space travel.
When Ellie returns, she estimates she was gone about 18 hours, only to find that in Earth time, it appeared she had never left. Her story is doubted, especially when it's revealed that her recording device recorded nothing but static.
When Ellie tries to persuade the others that she actually did travel through time, she is reminded of the principle of Occam's razor: that the easiest explanation tends to be the right one. Meaning, she probably never left.
Not until the end of the movie is it revealed that she recorded approximately 18 hours of static.
The principle of Occam's razor is generally attributed to William of Ockham (also spelled Occam) (c. 1285 - 1348), an English theologian, logician, and Franciscan friar. In William of Occam's terms, he wrote in Latin: "Numquam ponenda est pluralitas sine necessitate," or "Plurality must never be posited without necessity."
The basic principle, however, was enunciated as far back as Aristotle ("the more limited, if adequate, is always preferable") and Ptolemy (\"we consider it a good principle to explain the phenomena by the simplest hypothesis possible\"). It also has been related in the works of Isaac Newton (\"we are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances\").
Although the true origin of Occam's razor is debatable, William of Ockham historically gets the credit, in large part due to the writings in 1852 of Sir William Hamilton, 9th Baronet, a Scottish metaphysical philosopher who first coined the term "Occam's razor."
Occam's razor is used as a heuristic, or "rule of thumb" to guide scientists in developing theoretical models. The term "razor" refers to the "shaving away" of unnecessary assumptions when distinguishing between two theories. Among many other scientific uses, Occam's razor is used in biology to determine evolutionary change, and in medicine for use in diagnosis.
While Occam's razor is a useful tool, it has been known to obstruct scientific progress at times. It was used to accept simplistic (and initially incorrect) explanations for meteorites, ball lightning, continental drift, atomic theory, and DNA as the carrier of genetic information. Once more research was done and more evidence brought to light, however, new theories emerged based on the new information.
Occam's razor doesn't necessarily go with the simplest theory, whether it's right or wrong; it is not an example of simplicity for simplicity's sake. It merely tries to cut through the clutter to find the best theory based on the best scientific principles and knowledge at the time.
It is doubtful that when positing this principle, William of Occam knew he would be spawning a popular tag line. Besides the movie Contact, the principle has been mentioned in the television shows The X-Files, Fringe, House (in an episode called "Occam's Razor\"), and Castle as a means of finding the most logical solution to an illogical problem. Occam's razor has become part of the popular media, to be used as a scientific means of thwarting more fanciful and dubious explanations for strange phenomena that the heroes of such shows encounter, but for which there is no easy explanation.