Map of the cosmic
microwave background plotted from WMAP data
New Scientist, October 2011
Edited by Andy Ross
The universe might be spinning. Michael Longo at the University of Michigan
in Ann Arbor thinks so. At the heart of the story is conservation of parity:
the universe does not tell left from right.
In 2007, Longo was mining
the databases of the Sloan Digital Sky Survey (SDSS) to collect images of
about a million galaxies across the northern sky. He was looking for spiral
galaxies whose swirling arms were clearly visible, showing what direction
the galaxies are spinning in.
By 2010, Longo and his team had a
sample of 15,158 clearly rotating spiral galaxies, the farthest 1.2 billion
light years away. In most sectors of the northern sky, equal numbers of
galaxies were rotating to the right, or clockwise, and to the left,
anticlockwise. But along one direction, at about 10 degrees to our own
galaxy's spin axis, there were more left-handed spirals than right-handed
Longo looked at the southern sky, which is not covered by the
SDSS. Stretching off as far as the telescope could see, along the same axis
in the southern sky, he saw an excess of right-handed spirals. It was the
opposite view of the same effect.
Longo says that if the asymmetry is
real, the universe has a net angular momentum and was born in a spin.
Experiments in the sixties showed that CP symmetry, parity (P) and
charge (C) conservation together, is broken in nature. In 1967, Soviet
physicist Andrei Sakharov showed that CP violation in the early universe
could explain the predominance of matter over antimatter in the universe.
In 2004, Alexander, then at the Stanford Linear Accelerator Center
in Menlo Park, California, and colleagues showed that if gravity violated
parity in the first instants after the big bang, that would have produced
asymmetric gravitational waves, causing inflation to produce more matter
The cosmic microwave background has a uniform
temperature of some 2.7 K, but look closely and you see warmer and colder
spots. On the very largest scales, some of the spots seem to line up in a
direction dubbed the "axis of evil". The axis along which galaxies seem to
be rotating with the same handedness is roughly the axis of evil.
Longo suggests that an initially spinning universe brought on a
parity-violating asymmetry in gravity that allowed matter to prevail over
antimatter. And that process left the axis of evil in the cosmic background
radiation and the inconspicuous alignment of galaxies that he spotted.
AR Kurt Gödel found
time-loop solutions of Einstein's cosmological equations that required the
universe to be spinning. Einstein refused to take them seriously. He admired
Gödel's mathematical abilities but thought he had no feeling for physics. If
the universe really is spinning, time loops could exist, this mortal coil
could coil back on itself, Nietzsche's eternal recurrence could become more
than a poetic metaphor, and we would all be scrambling to revise our