The positive Whitehead double sliceness conjecture

Let $K$ be a knot in $S^3$. Its positive Whitehead double is the satellite knot obtained using the positive Whitehead pattern. Whitehead double sliceness conjecture. The knot $K$ is smoothly slice if and only if its positive Whitehead double is smoothly slice. This is a major open problem in smooth knot concordance; topologically, positive Whitehead doubles are always slice when the companion has trivial Alexander polynomial, while knot Floer theoretic results provide supporting evidence.