by The researchers used simulations to study the cosmic web, the filamentary pattern of galaxies that exists on a large scale throughout the universe. By treating the distribution of galaxies as a set of points and applying mathematical techniques developed for materials science, they quantified the relative disorder of the universe and gained a better understanding of its fundamental structure. Credit: NASA/University of Chicago and Adler Planetarium and Astronomy Museum
The universe is dotted with galaxies that, on large scales, exhibit a filamentary pattern, called the cosmic web. This heterogeneous distribution of cosmic matter is in some ways like blueberries in a muffin where matter clumps together in some areas but may be lacking in others.
Based on a series of simulations, researchers began to probe the heterogeneous structure of the universe by treating the distribution of galaxies as a collection of points – like the individual particles of matter that make up a material – rather than as a continuous delivery. This technique allowed the application of mathematics developed for materials science to quantify the relative disorder of the universe, allowing a better understanding of its fundamental structure.
Visualization of the largest structures in the universe from the Sloan Digital Sky Survey. Credit: NASA/University of Chicago and Adler Planetarium and Astronomy Museum
“What we discovered is that the distribution of galaxies in the universe is quite different from the physical properties of conventional materials, having its own unique signature,” explained study co-author Oliver Philcox.
This book, now published in Physical examination Xwas conducted by Salvatore Torquato, member and frequent visitor of the Institute for Advanced Study and Lewis Bernard Professor of Natural Sciences based in[{” attribute=””>Princeton University’s departments of chemistry and physics; and Oliver Philcox a visiting Ph.D. student at the Institute from September 2020 to August 2022, now a Junior Fellow in the Simons Society of Fellows, hosted at
This visualization presents a 3D view of the largest structures in the universe. It starts with data from the Sloan Digital Sky Survey and zooms out to reveal data from WMAP. Credit:[{” attribute=””>NASA/
A section of the universe (black and white), with dark matter halos indicated by points and their associated large-scale topological structures indicated by colors. Credit: Philcox & Torquato; The Quijote Simulations
“The perceived shift between order and disorder depends largely on scale,” stated Torquato. “The pointillist technique of Georges Seurat in the painting A Sunday on La Grande Jatte (see image below) produces a similar visual effect; the work appears disordered when viewed up-close and highly ordered from afar. In terms of the universe, the degree of order and disorder is more subtle, as with a Rorschach inkblot test that can be interpreted in an infinite number of ways.”
“A Sunday on La Grande Jatte” by Georges Seurat.
Statistical tools, specifically nearest-neighbor distributions, clustering diagnostics, Poisson distributions, percolation thresholds, and the pair-connectedness function, allowed the researchers to develop a consistent and objective framework for measuring order. Therefore, their findings, while made in a cosmological context, translate to a number of other dynamical, physical systems.
This interdisciplinary work, combining the techniques of cosmology and condensed matter physics, has future implications for both fields. Beyond the distribution of galaxies, many other features of the universe can be explored with these tools, including cosmic voids and the ionized hydrogen bubbles that formed during the reionization phase of the universe. Conversely, the novel phenomena discovered about the universe may also provide insight into various material systems on Earth. The team recognizes that more work will be needed before these techniques can be applied to real data, but this work provides a strong proof-of-concept with significant potential.
Reference: “Disordered Heterogeneous Universe: Galaxy Distribution and Clustering across Length Scales” by Oliver H. E. Philcox and Salvatore Torquato, 14 March 2023, Physical Review X.
DOI: 10.1103/PhysRevX.13.011038
