Letters

Galaxy clusters slide
Could the general motion of galaxy clusters (“Galaxy clusters slide to the south,” SN: 10/25/08, p. 12) be evidence of rotational motion of the matter components of the universe on a scale much larger than the observable universe? Would such motion not also result in accelerating expansion of the observable universe, as gravitational attraction opposing rotational expansion weakened as a result of expansion?
Arden Slotter, Castle Pines North, Colo.