COSMOLOGISTS called it the axis of evil. Spotted in 2005 in the cosmic microwave background, the all-pervading afterglow of the big bang, the axis was a peculiar alignment of features where we would have expected nothing but randomness.
The name was justifiably melodramatic, given that it threatened our established view of the universe. At the heart of that picture is the cosmological principle, which says that the universe appears the same on the largest scales no matter where you happen to be looking. This is what you’d expect in the aftermath of an explosion like our big bang, with all the constituents winding up mixed together in a randomised, homogeneous soup. The reality, it seemed, wasn’t like that – and despite steadily improving measurements, the axis has stubbornly refused to vanish.
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“This would be not just an axis of evil, but an axis of everything“
Cosmologist Jonah Miller at the University of Guelph in Ontario, Canada, is intrigued but sceptical of its significance. “Studying the axis of evil is certainly worthwhile. However, I don’t believe it represents a major gap in our understanding of early-universe cosmology.” He thinks the axis is just an example of what happens when you look at random data: familiar patterns will emerge by sheer chance, signifying nothing.
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But it’s not just the microwave ripples that seem odd. Wen Zhao, a physicist at the University of Science and Technology of China in Hefei, has been collecting a host of other . They include the movement of galaxies across the universe as well as the direction in which spiral galaxies’ arms curl. Not only that, but measurements of such unrelated phenomena as the temperature of the microwave background radiation, the value of the fine structure constant responsible for atomic structure, and even the acceleration of the universe’s expansion also all seem to vary as we move along that axis. Most oddly of all, these alignments point in the very direction that the solar system is moving through space.
If genuine, it’s not just an axis of evil, but an axis of everything. “If they were real features of the universe, it means that the cosmological principle will be violated, which is the basis of modern cosmology,” says Zhao.
Although alternative cosmologies have been proposed, most fall foul of the latest results from the European Space Agency’s Planck satellite, which suggest the universe is indeed more or less homogeneous. But there’s another wacky theory that chimes with the axis idea: that the universe could be rotating. Championed by Michael Longo at the University of Michigan, Ann Arbor, this rotation would impart angular momentum to galaxies as they form, helping them to spin in a preferred direction.
But the more bizarre the coincidences get, the more it suggests that something rather banal could be behind them. Zhao believes the sheer abundance of alignments shows that we must be getting something consistently wrong in our measurements. “Otherwise it is very difficult to understand why the cosmological preferred axes should coincide with the motion of the solar system,” he says.
This article appeared in print under the headline “Everything points in one direction”
