Slimy galaxies

How a microbe helped astronomers to solve a big problem – April 17, 2020

You might have come across it in Micropia: the slime mould, or Physarum polycephalum as it is known to our lab technicians. A single-celled organism that is known for, among other things, its ability to find food in a very ‘smart’ way. In the museum it can be viewed daily in the slime mould labyrinth, in which the slime mould is able to find the right path to some oat snacks. However, recently a group of astronomers went a step further. They used this intriguing microbe for a very high-flying goal indeed: charting the interrelationship between galaxies. They have published their findings in The Astrophysical Journal Letters.

Difficult matter

Astronomers have long been fascinated by the way galaxies are distributed through our universe and how they interrelate. The network through which galaxies are distributed is sometimes also called the ‘cosmic web’. However, one of the problems encountered by researchers is that this web is difficult to see because a large part of it consists of dark matter. This is a substance which we know exists on the basis of calculations, but which we can’t directly perceive. So in order to find out more about the nature of this mysterious web that connects galaxies, the astronomers called in the help of the lowly slime mould.

Slime mould simulation gives insight

The slime mould creates and uses threads to search for food in a particular way. On the basis of these search patterns, the group of researchers wrote a collection of calculation instructions, or algorithm. This algorithm was then used to perform simulations for the cosmic web. These simulations included information from no less than 37,000 galaxies. Comparisons between the results of the simulations and calculations about dark matter revealed that the slime mould is a good predictor of the cosmic web. Thanks to these new simulations it is finally possible to make the cosmic web ‘visible’ on a larger scale. Not bad for a single-celled microbe, right?