Is "may the force be equal to mass times acceleration" proper English?

Solution 1:

"May the force be equal to mass times acceleration" is perfectly grammatical. Your argument hinges on the fact that the force already is equal to mass×acceleration, but that is irrelevant here.

All the grammaticality requires is that a sentence can be parsed, not that it also makes sense or is true. We can even simplify the sentence to "may the force be the force", and simplify it further still to "may X be X"— which quite obviously is always true by definition —, and it still remains perfectly parseable and thus grammatical.

Besides, how do you mean that "in this sentence, no wish is being offered"? Of course there is. There is most clearly a wish. The whole point of the "may X be Y" construction is expressing a wish, and that holds for any and all values of X and Y.

Now, of course if you absolutely need to "fix" the sentence according to your criterion, it is perfectly doable, as you can always say "May the force stay equal to mass times acceleration", or "May the force continue to be equal to mass times acceleration", or what have you. But note how the only thing you are doing there is swapping a verb for a verb. That position requires a verb, and a verb is what you put there, and it makes no difference whatsoever which verb it is. I seem to be linking to "colorless green ideas sleep furiously" quite often these days, but it's most relevant here.

Oh and yes, take anything other than be and you'll be ruining the joke of course. Use the be, Luke.