Almost a century ago, astronomer Fritz Zwicky noticed something odd: galaxies in clusters were moving faster than the visible mass could account for. That’s how the mystery of dark matter was born — an invisible substance that holds everything together. One hypothesis suggests it’s not made of little particles but is a Quantum Field (a pervasive field with quantum properties) with spin 1. Such a field carries three polarizations (directions of oscillation), and physicists sometimes call these particles “dark photons.” Unlike other models, such as those involving axions (hypothetical spinless particles), here you have three “threads” that oscillate independently. Gravity forces these threads to twist into incredibly dense knots — Proca stars (quantum clumps resembling a Bose-Einstein condensate, named after physicist Alexandru Proca).
To understand how threads form these knots, scientists ran numerical simulations (supercomputer calculations). They solved equations first written down by Erwin Schrödinger, tracing the threads’ evolution from the universe’s earliest moments. Such fields are thought to arise during inflation — a brief period of super-fast expansion right after the Big Bang, an idea proposed by Alan Guth. The simulation covered an enormous time span: from an epoch when the redshift (a measure of cosmic expansion) was about 340 000, down to around 800. The simulation’s main result is a simple power-law: the mass of the central Proca star is proportional to the mass of the surrounding cloud raised to the power of 0,64. In other words, the heavier the cloud, the heavier the knot — but not linearly. This exponent is noticeably steeper than in cases where there’s only one thread (scalar fields). The difference reveals the field’s triple nature. The modeling also showed how these threads gradually build up the universe’s large-scale structure — a web of clusters and voids.
Knowing this rule helps predict how often such knots will collide. And collisions produce gravitational waves — ripples in space-time that future detectors could pick up. And so the triple thread, threading the cosmos from its very first moments, weaves itself into invisible stars. Solving their nature is just beginning.
A typical knot formed from these threads is about the size of Neptune’s orbit but weighs as much as an asteroid. A teaspoon of its core material would weigh tens of millions of tons.