Neutrons May Adopt Cubic Symmetry

Under very specific conditions, spherical and incompressible neutrons may take on cubic symmetry. According to a new study, this can only happen inside the extreme-pressure environment of neutron stars, whose cores are extremely dense.

The latest calculations indicate that a tablespoon of matter from the core of such an object may weigh in excess of 100 trillion tons here on Earth. Neutron stars form when the cores of massive stars collapse in supernova explosions.

When massive stars reach the end of their burning cycles – and expel their atmospheres in violent supernova blasts – their cores can either collapse into a neutron star or a black hole, depending entirely on how much mass the progenitor star had.

The former can then grow in mass until it reaches a critical threshold. Once this happens, it can collapse yet again, this time into a black hole. However, once a black hole is formed, it can go on to grow without collapsing further.

Given that both classes of objects have tremendous mass and gravitational pulls, the matter at their cores exists in very odd states. In the new study, experts propose that even the neutrons inside atoms can become crushed by the tremendous pressure exerted by mass.

Once thought to be incompressible, these elementary particles may in fact be able to suffer deformations, but only under extreme pressure conditions. Rather than staying spherical, they can reshape themselves to become cubic, allowing for an even more packed arrangement.

Researchers behind the new study – led by expert Felipe J. Llanes-Estrad from the Technical University of Munchen, in Germany – estimate that the transition requires an energy expenditure of 150 megaelectronvolts (MeV).

What the new investigation does is provide an alternative explanation on the nature of the highly-compressed matter experts observe inside neutron stars. Other studies suggested that extreme gravitational compression in fact causes neutrons to collapse into strange quark matter.

In the new theory, neutrons are not crushed, but simply reshaped into a tighter arrangement. The experts say that the new arrangement might be as much as 75 percent tighter than the spherical one.

In part, the new theory was developed in response to the discovery of the neutron star PSR J1614–2230, back in 2010. The object, featuring a diameter of less than 20 kilometers, was determined to tip the scales at two solar masses, which is a tremendous weight for its size.

This theory also does away with the necessity of having stars made up of strange quark particles (strange stars) scattered throughout the Universe. However, it replaces these exotic objects with equally exotic cubic neutron stars, which is arguably just as odd, Universe Today.