When you have lived as long as I have, evolution is visible... at least of the spoken word. I have noticed of late, at any retail counter (of the non-formal type - my guess is this probably does not apply if one is buying a $600 dress or similar) whether it be fast food, discount store, or grocery store that I am told to "have a good one" (or more often than not it is "have a gudt one" with an umlaut over the u) as I leave. This leads one (or at least my warped mind) to wonder... one what? I will admit that if you have to have "one', it being a good "one" as opposed to a bad "one" is probably preferred. As I said when I started, I have seen (or heard) the evolution of language in my lifetime. We would have just said "goodbye" or "see you later". Maybe in a retail setting "thanks". In the feel good 60s and early 70s it became - "Have a nice day." Here is how Merriam-Webster defines "nice...
The universe, by definition, is infinite. It is arrogant for us to think mankind can formulate all the questions much less grasp all the answers.