Overview

For decades, we have studied the sky from every angle, examining its behavior and deducing its most fundamental principles. However, some details may be eluding us, as well as the potential of comprehending the laws that gave origin to the universe in which we live. According to a recent discovery, what we think of as a symmetrical and homogeneous universe may actually be an unbalanced system in which one section of the cosmos has more galaxies than another.

The science and other stuff to know

The notions of symmetry and parity are highly valued in physics: they are characteristics that physicists love to find in their systems because they greatly simplify them. To be symmetrical, something must have an axis via which one side of the object is reflected in the other. When something exhibits parity, on the other hand, it signifies that its behavior and structure are identical when mirrored in a mirror.

If one considers an engine, for example, and builds a mirror version (its specular reflection), the engine should work the same way. This is true for many of physics’ fundamental laws. Until recently, it was thought to be a large-scale condition of the universe. That is, the distribution of galaxies complied with parity: when considering any galaxy configuration and its mirror image, both arrangements should emerge in the cosmos with the same probability. However, two recent studies indicate that this may not be the case.

Oliver Philcox is an astrophysicist at Columbia University in New York. In September, he published an article in Physical Review Letters where he evidenced the imbalance between galaxy arrangements and their specular reflections. The arrangements he used are in the shape of a three-dimensional tetrahedron—a body built from 4 points. Philcox found the disparity between “left-handed” and “right-handed” tetrahedrons to be significant.

Simultaneously, a second study reaffirmed the disparity. In a preprint, the authors suggest that the imbalance is of the order of three times greater than that proposed by Philcox.

Both studies provide compelling evidence of a parity violation that should be investigated further.

So what?

A parity violation implies new physics since it exposes a flaw in our existing theories, implying that something in our models is incorrect or incomplete. The investigation and verification of this disparity could give information on the primordial mechanisms that created the universe in its early stages. It may also aid in our understanding of the origin and existence of other disparities, such as matter-antimatter asymmetry.

What’s next?

The study of cosmic inflation models could yield a plausible explanation for the observations of asymmetry in galaxy arrangements. Some of the experts who work in this field are inclined to approach the enigma with other theoretical tools, such as the so-called Chern-Simons gravity mode.

In any case, the verification of this discrepancy will mean a real break in the foundations of the current cosmological mode, sowing the seeds of new physics.