Updated: Oct 6
As Carl Sagan famously said, “The cosmos is within us. We are made of star-stuff. We are a way for the universe to know itself.” The matter that makes up our bodies and the other life on this planet was formed from remnants of stars. As we seek to understand the cosmos and stretch back towards the stars, some of the smallest organisms can be helpful in surprising ways.
Slime molds are some of the most unique organisms we have discovered, and as a result they have been challenging to classify. Originally thought to be fungi, slime molds are protists that cycle between existing as microscopic, single-celled amoebas to fusing into large plasmodia. These plasmodia are essentially giant, multinucleated cells that can be seen with the naked eye. One species of slime mold, Physarum polycephalum (also known as “the blob”), naturally builds complex, near-optimal networks of filaments in its search for food.
In 2020, a group of researchers at University of California Santa Cruz used the cobweb structure formed by P. polyceophalum as a model for the filaments created by gravity that tie galaxies together. This “cosmic web” is primarily composed of dark matter, which we cannot see, combined with gas. These filaments connect galaxies across the universe and form the boundaries between them.
The group designed an algorithm based on the branching growth pattern of the slime mold and tested it against a simulation of the growth of these dark matter filaments to find efficient, continuous paths between galaxies. This allowed them to create a 3D map of the cosmic web in the local universe.
This might seem like a stretch, but the branching patterns of slime molds have also been used to solve mazes, find evacuation routes, and plan efficient traffic patterns. Other microorganisms serve as models for our understanding of nearly every aspect of biology. Through these endeavors, the UCSC group showed that, by thinking imaginatively, some of the smallest organisms on earth can impact our understanding of the broader universe.
Burchett, J. N., Elek, O., Tejos, N., Prochaska, J. X., Tripp, T. M., Bordoloi, R., & Forbes, A. G. (2020). Revealing the Dark Threads of the Cosmic Web. The Astrophysical Journal, 891(2), L35. https://doi.org/10.3847/2041-8213/ab700c