Axis of evil (cosmology)

Lore & Background

The 'axis of evil' was dubbed in 2005 by Land and Magueijo to describe an unexpected alignment between the plane of the Solar System (the ecliptic) and features of the cosmic microwave background. Observations showed that the 'top half' of the CMB is slightly cooler than the 'bottom half,' and the quadrupole and octupole axes are only a few degrees apart, aligned with this divide. This alignment suggested a special position for Earth, contradicting the Copernican principle that Earth is not central or privileged.

Reader's Guide

The significance of the 'axis of evil' lies in its potential to challenge fundamental cosmological assumptions. If the alignment is real, it would imply that the Solar System's orientation is correlated with large-scale structure of the universe, a violation of the Copernican principle. However, the evidence is disputed: a 2016 study comparing isotropic and anisotropic models against WMAP and Planck data found no evidence for anisotropy. Earlier studies suggested systematic errors or psychological effects, as noted by WMAP chief scientist Charles L. Bennett. The Planck data published in 2013 showed stronger evidence for the anisotropy, but masking techniques may introduce errors that render the anomaly not statistically significant. As of 2015, no consensus existed on the nature or statistical significance of the axis of evil.

Did You Know?

• The term 'axis of evil' was coined by Land and Magueijo in 2005.
• The alignment involves the quadrupole and octupole axes being only a few degrees apart.
• A 2016 study found no evidence for anisotropy when comparing isotropic and anisotropic models against WMAP and Planck data.
• Chief scientist Charles L. Bennett suggested coincidence and human psychology as possible explanations.