Physicists at MIT and elsewhere discovered some shifty behavior while studying the strong nuclear force — the interactions between neutrons and protons — at very short distances, which naturally occur deep within the maddeningly-hot cores of neutron stars, according to a new study published in the journal Nature.
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The strong nuclear force inside neutron stars
The majority of matter in the universe holds together with a subatomic glue called the strong nuclear force — one of four forces fundamental to the composition of nature in empirical science. The others — gravity, electromagnetism, and the weak force also pervade our daily lives. However, the strong nuclear force pulls and pushes in the space between neutrons and protons in an atom's nucleus. This is what keeps an atom from collapsing inward.
Normally, protons and neutrons are far enough away from one another that physicists can predict their interactions with great accuracy. But these predictions fall apart when subatomic particles are so close that they're practically juxtaposed.
Ultrashort distances like this are extremely rare on Earth, but they happen all the time in neutron stars, where matter is squeezed into extremely dense pockets by immense gravity. Scientists have wanted to explain how the strong nuclear force works in ultrashort distances since the dawn of nuclear physics.
The indifference of performance under pressure
The team did an advanced analysis on particle accelerator data from earlier experiments and discovered that the distance between protons and neutrons shrinks, which baffled the physicists.
At large distances, the strong nuclear force attracts a neutron to a proton, but with little distance, the force becomes indifferent: it can attract, but sometimes it also repels.
"This is the first very detailed look at what happens to the strong nuclear force at very short distances," said Or Hen, an assistant professor of physics at MIT. "This has huge implications, primarily for neutron stars and also for the understanding of nuclear systems as a whole."
The fabric of reality is mesmerizing, but in a part of our galaxy far, far away, the type of atoms of Hen and his colleagues' study are performing a shifty indifference under unimaginable pressure, using a force we can assume will be with neutron stars, always.