Almost everywhere in the observable universe the minimum intergalactic temperatures are observed to be 2.725K. This is accomplished assertively by the removal of all other heat sources, stellar and galactic. This assertively is accomplished by precision measurements and the resultant minimum temperature variation is very small. Even so, some large scale features of the CMBR as we have determined it appear to be statistically aligned with the direction and angle of our solar system, and the Earth itself moving though our galaxy. How can this be? Some have claimed that this alignment and its statistical significance is not great enough to provide proof that the CMBR is not from a singular Big Bang event, unrelated to our perspective of it. Others claim it to be another big theoretical problem.

Also if 2.725 K is the CMBR temperature, then why is the temperature within some voids 10% lower than the mean temperature elsewhere, about 2.45K? The lack of galaxies within them would be an obvious explanation, but this answer would be inconsistent with the proposed heat source of the CMBR.

These problems collectively are called the “Axis of Evil.”