The use of idiom in popular science writing:
"It was only in the fall of 1943 that the young German physicist C. Weizsäcker cut through the Gordian knot of the planetary theory. Using the new information collected by recent astrophysical research, he was able to show that all the old objections against the Kant-Laplace hypothesis can be easily removed, and that, proceeding along these lines, one can build a detailed theory of the origin of planets, explaining many important features of the planetary system that had not even been touched by any of the old theories."
George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.
Most metaphors are designed to offer a comparison which a reader/listener will immediately be able to 'decode', to work out how the comparison is being used. (Whether metaphors are always successful in this sense is a moot point!)
Idioms are phrase that have become established in the language but may not be clear to uninitiated. To say that Weizsäcker "cut through the Gordian knot" of the planetary theory is to use a metaphor that relates to a specific cultural reference (Alexander the Great thinking outside the box by cutting through a knot rather than taking time to untie it) that will not be obvious to a reader who does not know the specific reference.
Read about communicating science through idioms
