  The ultra-low density limit of Saha ionization formula suggests that, in this
limit, matter would prefer to remain ionized.This has a very important
implication for cosmic structures known as Voids.These are ultra-low density
(much less than average density of matter in the Universe) regions in the
galactic clusters and superclusters.The ionization formula implies that matter
trapped in the Voids should be ionized.Therefore, we expect a very faint
radiation glow from the Voids resulting from the motion of the charged
particles.
