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

Victoria D. Doty

A brainless, one-celled organism with a knack for finding foods is assisting astronomers study the largest, most mysterious framework in the universe — the cosmic website. But, 1st, factors could get a little bit slimy. 

The cosmic website is a extensive community of interconnected filaments designed of dark matter and fuel that forms the scaffolding the full universe is created upon. These filaments can extend hundreds of tens of millions of gentle-a long time, and they hook up galaxies, galaxy clusters and even galaxy superclusters. Having said that, mainly because the cosmic website is unbelievably faint — and the dark matter within just it does not interact with gentle — it’s really complicated to map.  

To deal with this problem, researchers at the College of California, Santa Cruz, sifted by means of archived info for extra than 37,000 galaxies ahead of charting their positions in the sky. They then used a subtle algorithm to map out the invisible filaments of fuel and dark matter between those galaxies to ascertain how they are interacting with just about every other, as properly as how the cosmic website influences star development in these galaxies. 

But this wasn’t your normal algorithm. As an alternative, the researchers used a product encouraged by slime mildew — specifically, the species Physarum polycephalum.

This algorithm mimics the mold’s foods-trying to get habits, which sends out tendrils of reconnaissance mildew to hunt for nearby foods. If a unique mildew thread stumbles on foods, it thrives, producing a sturdy relationship between the foods and the relaxation of the colony.

So by substituting individual galaxies for the mildew-based algorithm’s “food,” researchers have been ready to produce a 3D map that implies how the galaxy-connecting filaments of the cosmic website are intertwined.

By the way, the fuel between galaxies also acts as a sort of “cosmic food” that fuels star development. And after you know how cosmic website filaments are linked to a galaxy, you can hazard a guess at the charge at which the galaxy is — or is not — forming stars. These a prediction is based on no matter whether or not a galaxy is linked to the cosmic website, as properly as how tightly sure it is to other galaxies. If it’s linked far too strongly, it runs the risk of drying up opportunities for star development far too loosely, and it cannot get to sufficient fuel. 


Scientists seeded an algorithm encouraged by the foods-trying to get habits of slime mildew with the positions of about 37,000 galaxies, exactly where the galaxies served as the “food.” This assisted them product and create a 3D map of the cosmic website connecting these galaxies. Earlier mentioned, the galaxies (or foods) are shown in yellow, whilst the cosmic website is shown in purple. (Credit history: NASA/ESA/J. Burchett and O. Elek/UC Santa Cruz)

From Slime to Space

The concept to use a slime-based algorithm to map the cosmic website arrived from co-creator Oskar Elek, a UC Santa Cruz computational media write-up-doc. He had earlier witnessed the operate of slime mildew algorithms, so he urged Joe Burchett — an astronomer at UC Santa Cruz and direct creator of the new paper — to use it to his operate on the cosmic website, whose framework stays elusive.

“He really despatched me display photographs of the info equipped with this ultimate algorithm,” Burchett claims. “What I observed was a trace of the reconstruction of the cosmic website that appealed much, much, much extra to my intuitive sense of what the cosmic website should really search like [compared with previous styles].”

This is not the 1st time scientists have used slime molds to map many buildings. Slime molds are skilled filament builders, developing complicated underground networks that assist them lookup for foods and means. These one-celled organisms operate as a person huge colony that can be up to one foot in diameter. And, oddly, their filamentary buildings clearly show a propensity for what could be described as trouble-fixing.

Slime molds are adept at “shortest path” issues, this sort of as finding the very best way to weave by means of a maze to find foods concealed within just. It is been termed “slime mildew computing” ahead of, and even likened to a rudimentary intelligence — though this naturally comes with its possess subset of thorny concerns. 

“For a slime mildew, the earth is a blend of two fields: gradients of attractants [things it wants] and gradients of repellents [things it avoids],” Andrew Adamatzky, a professor in unconventional computing at the College of West England, wrote in an email. “The slime mildew basically follows the gradients. This is how it calculates, for illustration, the shortest route.”

By tracking how the slime mildew algorithm linked separate galaxies, researchers realized exactly where to search for cosmic website filaments in archived observations. “Wherever we observed a filament in our product,” Burchett said in a statement, “the Hubble spectra confirmed a fuel signal, and the signal bought much better towards the middle of filaments exactly where the fuel should really be denser.” This implies the researchers not only used the algorithm to efficiently pinpoint exactly where threads of the cosmic website should really be, but also really find them.

“For the 1st 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 said. “These final results not only ensure the framework of the cosmic website predicted by cosmological styles, they also give us a way to increase our being familiar with of galaxy evolution by connecting it with the fuel reservoirs out of which galaxies variety.”

The new investigation was revealed March 10 in The Astrophysical Journal Letters.

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