Divisibility of spheres with measurable pieces

Abstract

For an $r$-tuple $({\gamma }_1,\dots ,{\gamma }_r)$ of special orthogonal $d\times d$ matrices, we say that the Euclidean $(d-1)$-dimensional sphere ${\mathbb{S}}^{d-1}$ is $({\gamma }_1,\dots ,{\gamma }_r)$-divisible if there is a subset $A\subseteq {\mathbb{S}}^{d-1}$ such that its translations by the rotations ${\gamma }_1,\dots ,{\gamma }_r$ partition the sphere. Motivated by some old open questions of Mycielski and Wagon, we investigate the version of this notion where the set $A$ has to be measurable with respect to the spherical measure. Our main result shows that measurable divisibility is impossible for a "generic" (in various meanings) $r$-tuple of rotations. This is in stark contrast to the recent result of Conley, Marks and Unger which implies that, for every "generic" $r$-tuple, divisibility is possible with parts that have the property of Baire.