Physicists and astronomers have long believed that the universe has mirror symmetry, like a basketball. But a study from the University of Michigan (USA) suggests that the shape of the Big Bang may have been more complex than previously believed, and thatthe newborn universe spun on an axis.
In theory, the mirror image of a galaxy rotating counterclockwise should have a clockwise rotation. The existence of more galaxies of one type than the other would be evidence of a symmetry breaking or, as physicists say, a “violation of parity” on cosmic scales. Studyingmore than 15,000 spiral galaxies with the Sloane telescope, in New Mexico, physicist Michael Longo and his colleagues have foundevidence that galaxies tend to rotate in a preferred direction, specifically to the left, in the region of the sky toward the north pole of the Milky Way. The effect extends beyond 600 million light years. “The difference is small, 7 percent more, but the probability that this could be caused by a cosmic accident is around one in a million”, clarifies Longo, who has released his conclusions in the magazinePhysics Letters B. “The results are extremely important because they seem to contradict the almost universally accepted notion that on a large enough scale the universe is isotropic, that is, it has no special direction.”
The finding gives clues abouthow the big bang came about. A symmetric and isotropic universe would have started with a spherically symmetric explosion, shaped like a ball. But if the universe had been bornlike a spherical ball spinning, Longo clarifies, it would have a preferred axis and the galaxies would have retained the initial movement, as it seems to be the case.
