Sierpinski has proved the following two interesting theorems.

**Theorem 1.** The Euclidean plane $\mathbb{R}^2$ is not a union of nondegenerate disjoint circles.

**Theorem 2.** The Euclidean space $\mathbb{R}^3$ *is* a union of nondegenerate disjoint circles.

In the second of the two main parts of his proof, Sierpinski blows a circle until it fits his needs. Thinking about this, it seems that if one uses *rotations* instead, one obtains the following theorem.

**Theorem 3.** The Euclidean space $\mathbb{R}^3$ is a union of disjoint *unit* circles.

The reason is that fixing a point on the unit circle, the intersection of every three rotations about this point contains just this point.

I think this version is much more cute. E.g., note that the analogous version of Theorem 1 becomes much more obvious when restricting to unit circles (one can have at most countably many disjoint unit circles in the plane!). Also, unit circles are not special. One only needs the following property of the desired curve.

**Free Rotations Property.** There exists a point on the curve such that, considering rotations of the curve about this point, every uncountable intersection of such rotations contains only the rotation point.

Thus, the theorem applies, e.g., to any regular polygon of perimeter 1, or even to a
fixed "8" shape (a nice name for Theorem 3 may thus be *Room for 8* :) ). In the plane,
it is known that even if we allow deforming the 8 figures, we cannot have more than countably many of disjoint 8's.

In fact, I do not know a curve *not* having the Free Rotations Property.
Maybe even for each "nice enough" curve there is a finite number $k$ and a rotation point
on it such that every $k$ rotations intersect in one point only.

**My questions (**
Assuming that my analysis is correct **):**
Is the above known? If yes, could you provide a reference?
What is the largest known class of curves with the mentioned Free Rotations Property?