In Season 1 Episode 11, Leonard tells an ill Sheldon to “drink plenty of fluids”. Sheldon replies by saying, “What else would I drink? Gases? Solids? Ionized plasma?”. Any high school chemistry student would be able to tell you that gases are, in fact, fluids. Any Sc.D would be able to tell you that plasmas are also fluids. ‘Fluid’ is often assumed to be synonymous with ‘liquid’, however, this is not the case. The definition of a fluid is a substance that has no fixed shape and yields easily to external pressure e.g. liquids, gases and plasmas. Sheldon’s implication is that a fluid is a state of matter separate from other states. Meanwhile, all four states of matter can, in fact, be fluids.
For a regular Joe, this is an honest mistake; the term “drink plenty of fluids” is rather colloquial. Technically, you are inhaling fluids as we speak. However, Sheldon’s response furthers the technical ignorance of their conversation.
Thanks to David Grounds for the submission.