Quadratic-Time Hardness of Furthest Pair in Superconstant Dimension
Furthest Pair and its relatives admit $f(d)\,n^{2-\Theta(1/d)}$ algorithms, making them the standard examples of barely subquadratic computation, and whether that is optimal in superconstant dimension was open. Under SETH it is: Furthest Pair requires quadratic time once the dimension is superconstant.