If we know the answer, then the question can be found

In Douglas Adams’ sci-fi series The Hitchhiker’s Guide to the Galaxy, a machine spends millions of years computing the answer to the ultimate question before anti-climactically announcing the answer: “42”. I would like to propose a hypothetical method of discovering what the ultimate question is (given that we now know the ultimate answer) if this machine existed in our world.

First of all, we have to recognize that out of the many questions in the world, there are only so many that have “42” as an answer. Most questions, in fact, have other answers. We can automatically exclude questions with yes/no answers, questions with the form “what do you call an X that has qualities Y,” questions that begin with “Why does…”, etc. We can exclude all questions that don’t have “42” as an answer. And since all questions (for the purposes of this hypothetical) that have the answer “42” are questions asking for a number, we can infer from this that the ultimate question must be one with a number as its target.

This leaves questions with the form: “How many Xs have Y qualities?”, “What is the product of this particular mathematical combination,” “How old was person X when Y,” and probably some others. The point is, while the amount of possible questions that can be asked with the answer “42” are infinite, the amount of forms within which the questions can be asked are limited. So, in order to figure out what the ultimate question would be, we then next need to figure out the ultimate form.

Presumably, not all forms of questions are created equal. If something is the “ultimate,” then one does not need any others. It is less like a specialty knife with just one intended purpose and more like a Swiss-army knife, that can be used for a variety of tasks. If there were an ultimate question, it would either itself be generalizable, or it would get at an answer with the most total explanatory power. The question would lead to a theory of everything, or could be abstracted in such a way, that through its form, anything could be found out. In short, the ultimate question could merely be a blue-print for asking more questions.

This blog post isn’t really trying to find Douglas Adams’ ultimate question per se. He reveals it in the second book (“what do you get when you multiply 6 x 9”), and the joke works like a kind of Buddhist koen, suggesting that our human reason cannot square the question with the answer because the universe is ultimately beyond comprehension. But in science, we search for natural laws, starting with the specifically observable, and attempting to find the general to explain it, starting with the answer and trying to find the question. Perhaps one of the most difficult problems facing scientists today is simply: “X?”