‘Slime Mold’ Helps Astronomers Map the Universe’s Dark Matter

Nancy J. Delong

A brainless, solitary-celled organism with a knack for locating food items is assisting astronomers research the greatest, most mysterious composition in the universe — the cosmic website. But, first, things could get a bit slimy. 

The cosmic website is a large network of interconnected filaments built of darkish issue and fuel that sorts the scaffolding the full universe is designed upon. These filaments can stretch hundreds of hundreds of thousands of gentle-several years, and they link galaxies, galaxy clusters and even galaxy superclusters. Nevertheless, due to the fact the cosmic website is very faint — and the darkish issue inside of it doesn’t interact with gentle — it’s particularly tough to map.  

To tackle this problem, researchers at the College of California, Santa Cruz, sifted by means of archived details for a lot more than 37,000 galaxies in advance of charting their positions in the sky. They then utilised a sophisticated algorithm to map out the invisible filaments of fuel and darkish issue among all those galaxies to ascertain how they are interacting with just about every other, as properly as how the cosmic website influences star formation in these galaxies. 

But this was not your common algorithm. Instead, the researchers utilised a model motivated by slime mold — exclusively, the species Physarum polycephalum.

This algorithm mimics the mold’s food items-looking for habits, which sends out tendrils of reconnaissance mold to hunt for close by food items. If a precise mold thread stumbles on food items, it thrives, producing a potent link among the food items and the relaxation of the colony.

So by substituting person galaxies for the mold-dependent algorithm’s “food,” researchers had been capable to create a 3D map that indicates how the galaxy-connecting filaments of the cosmic website are intertwined.

By the way, the fuel among galaxies also functions as a variety of “cosmic food” that fuels star formation. And at the time you know how cosmic website filaments are related to a galaxy, you can hazard a guess at the level at which the galaxy is — or is not — forming stars. These types of a prediction is dependent on whether or not or not a galaxy is related to the cosmic website, as properly as how tightly sure it is to other galaxies. If it’s related far too strongly, it runs the threat of drying up possibilities for star formation far too loosely, and it can’t get to more than enough gasoline. 


Scientists seeded an algorithm motivated by the food items-looking for habits of slime mold with the positions of about 37,000 galaxies, where the galaxies served as the “food.” This aided them model and make a 3D map of the cosmic website connecting these galaxies. Previously mentioned, the galaxies (or food items) are proven in yellow, though the cosmic website is proven in purple. (Credit rating: NASA/ESA/J. Burchett and O. Elek/UC Santa Cruz)

From Slime to Space

The notion to use a slime-dependent algorithm to map the cosmic website came from co-author Oskar Elek, a UC Santa Cruz computational media article-doc. He had previously seen the get the job done of slime mold algorithms, so he urged Joe Burchett — an astronomer at UC Santa Cruz and lead author of the new paper — to use it to his get the job done on the cosmic website, whose composition remains elusive.

“He truly despatched me screen shots of the details equipped with this closing algorithm,” Burchett says. “What I noticed was a trace of the reconstruction of the cosmic website that appealed a lot, a lot, a lot a lot more to my intuitive perception of what the cosmic website should really look like [when compared with earlier types].”

This is not the first time researchers have utilised slime molds to map a variety of constructions. Slime molds are expert filament builders, constructing elaborate underground networks that aid them search for food items and methods. These solitary-celled organisms get the job done as 1 huge colony that can be up to 1 foot in diameter. And, oddly, their filamentary constructions demonstrate a propensity for what could be described as challenge-solving.

Slime molds are adept at “shortest path” difficulties, these types of as locating the best way to weave by means of a maze to track down food items hidden inside of. It is been termed “slime mold computing” in advance of, and even likened to a rudimentary intelligence — although this naturally comes with its own subset of thorny queries. 

“For a slime mold, the globe is a combination of two fields: gradients of attractants [stuff it desires] and gradients of repellents [stuff it avoids],” Andrew Adamatzky, a professor in unconventional computing at the College of West England, wrote in an electronic mail. “The slime mold simply follows the gradients. This is how it calculates, for instance, the shortest route.”

By monitoring how the slime mold algorithm related separate galaxies, researchers knew where to look for cosmic website filaments in archived observations. “Wherever we noticed a filament in our model,” Burchett claimed in a statement, “the Hubble spectra showed a fuel sign, and the sign got more robust towards the center of filaments where the fuel should really be denser.” This usually means the researchers not only utilised the algorithm to properly pinpoint where threads of the cosmic website should really be, but also truly discover them.

“For the first time now, we can quantify the density of the intergalactic medium from the distant outskirts of cosmic website filaments to the very hot, dense interiors of galaxy clusters,” Burchett claimed. “These benefits not only verify the composition of the cosmic website predicted by cosmological types, they also give us a way to improve our comprehension of galaxy evolution by connecting it with the fuel reservoirs out of which galaxies form.”

The new study was posted March 10 in The Astrophysical Journal Letters.

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