Richard Friedberg, then an undergraduate pre-medical student, independently solved Post's problem (of whether there are intermediate Turing degrees) by the priority-injury method. This was a significant open problem at the time, so the result made news:

• 1956 news article "Senior solves logic problem, astounds mathematicians"

In Gödel's now famous letter to von Neumann that introduced the P vs NP problem, Gödel wrote

I do not know if you have heard that “Post’s problem”, whether there are degrees of unsolvability among problems of the form (∃y)φ(y, x), where φ is recursive, has been solved in the positive sense by a very young man by the name of Richard Friedberg. The solution is very elegant. Unfortunately, Friedberg does not intend to study mathematics, but rather medicine (apparently under the influence of his father).

Friedberg ended up becoming a physicist (Wikipedia biography).