How slime mold helped scientists map out the cosmic web
Creeping tendrils of slime seem to mirror the structure of the universe’s enormous filaments. That superficial similarity, in an organism called a slime mold, helped scientists map out the cosmic web, the vast threads of matter that connect galaxies. Made up of gas and the unidentified substance called dark matter, the cosmic web began forming early in the universe’s history, as matter clumped together due to gravity. Computer simulations of that formation suggest that a tangled tatting should link galaxies, but the web is so ethereal that scientists struggle to image it directly (SN: 10/3/19). Enter the slime mold Physarum polycephalum, a single-celled organism that appears as a slimy yellowish lace, often seen bedazzling rotting tree trunks. Normally, a slime mold forms connections between sources of food. Its patterns have striking similarity to human-made networks, such as railroads (SN: 1/21/10). Scientists produced this map of the universe’s cosmic web based on locations...