"Hi, I'm a Google search engineer. Anon User and did some excellent analysis. As a web search query, [-4^(1/4)] is interpreted like [-4 "1 4"], as in "Find me pages which contain a 1 next to a 4, but which do not contain a 4." This should return zero results, because it is impossible to satisfy both requirements. However, we have uncovered a bug that causes some web pages to "match" these contradictory queries. Since these are the only results that "match" the query, they are the results that get shown. We are working on a bug fix. Thanks to the Quora community for bringing this to our attention."
This is what the software engineer replied to the matter. It seems that a bug is causing porn results to show up when something 'impossible' is searched for. The bug is currently being fixed, and Jeremy Hoffman thanked the users of the website for exposing the bug.