Explanation:
What has created this huge empty volume in the universe?
No one is yet sure, and even the extent of the estimated billion-light year
void is being researched.
The void
is not a hole in space like a
black hole,
but rather a vast region of the universe that appears to be mostly devoid of
normal matter
and even dark matter.
The void is still thought to contain
dark energy,
though, and is clearly traversable by light.
The void's existence is
being postulated
following scientific curiosity about how unusually cold spots came to appear on
WMAP's map of
cosmic
microwave background (CMB) radiation.
One possibility was that this CMB region was not actually
very cold but light from the spot somehow became less
cosmologically redshifted than normal along the way.
Other voids
in the universe are known to exist,
but this void appears to have an unusually large gravitational effect,
and so might possibly be the largest in our entire visible universe.
Investigating this, a recent study found an unusually low number of
cosmic radio sources
between Earth and the CMB cold spot, which led to the inference of this giant void.
An artist's depiction
of the huge cosmic void is
shown above.
