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  • [♪ INTRO]

  • One of the best ways to solve problems in science can be, well,

  • borrowing from other kinds of sciencebecause there are often surprising connections

  • between disciplines that seem totally unrelated.

  • Sometimes, though, these connections can go from unrelated to like, far-fetched.

  • Like, that can't be a thing!

  • Like, say, slime molds predicting the shape of matter in the universe.

  • And yet, in a paper published last week in the Astrophysical Journal Letters,

  • a team of researchers claim their model based on slime mold

  • is so far our best predictor of the distribution of matter in the universe.

  • The team was trying to predict the shape of the cosmic web,

  • the thread-like network of matter that spreads through the whole universe.

  • It hasn't always looked the way it does todayand understanding how the cosmic web

  • has evolved over time is key to understanding the forces driving its structure.

  • Go back to just after the Big Bang, and stuff was spread

  • pretty much uniformly throughout space.

  • Then, gravity started to take over.

  • Areas with a little extra density began to pull other material in

  • so denser areas got even denser and less-dense areas emptied out

  • until a net-like structure formed.

  • At dense spots where strands intersected, clumps of matter eventually collapsed

  • into the first galaxies, loosely connected by tendrils of gas and dust

  • called the intergalactic medium.

  • Because their stars give off light, astronomers today can map

  • the locations of the galaxies pretty easily.

  • But uncovering the web has proven to be harderat least, until we got a little help

  • from Physarum polycephalum, a slime mold.

  • P. polycephalum is basically just one big cell, but for a single cell,

  • it is surprisingly complex.

  • It has a bunch of nuclei but no brain, yet it can form memories, learn,

  • and even pass on that knowledge to other slime molds.

  • Most important for the team of astronomers, though, is how it moves.

  • When searching for food, the slime mold sends out bits of itself in all directions.

  • If one part finds a source of food, it flourishes and the whole organism

  • kind of grows in that direction.

  • And that's not all that different from how clusters of matter grow,

  • if you imagine that anything with gravity is like a source of food for the cosmic web.

  • In fact, a postdoc at UC Santa Cruz realized that, mathematically,

  • the evolution of the cosmic web was pretty similar to the growth of slime mold.

  • So, to apply this technique to the cosmic web, the team took

  • a computer model for slime mold growth and modified it

  • for the three-dimensional nature of space.

  • Then, they marked the present-day locations of galaxies as food sources

  • and let the mold grow.

  • The result was basically a map of possible connections between galaxies near and far.

  • The stronger the link, the thicker the web.

  • To check their results, the team compared these predictions

  • with hundreds of observations made by the Hubble Space Telescope.

  • And it worked!

  • Where the slime mold model said there should be gas, there was gas.

  • Where it said there should be a lot of gas, they found that, too.

  • So does this mean that slime molds and galaxies are actually connected

  • and that we're all just the same thing?

  • No.

  • Not exactly.

  • But it does mean that living things often use pretty efficient techniques

  • to solve problems, whether they know it or not.

  • And it shows us that a brainless organism can help us tackle one

  • of the most complex problems in cosmology.

  • Closer to home, scientists from Europe's Rosetta mission

  • might have solved another mystery recently:

  • why many comets seem to be missing a bunch of nitrogen.

  • Nitrogen is one of the most abundant elements in the universe,

  • yet when scientists study comets, they find around ten times less than they expect.

  • In a paper published in the journal Nature Astronomy back in January,

  • Rosetta scientists explain why that might be.

  • Between 2014 and 2016, the Rosetta spacecraft studied

  • Comet 67P/Churyumov-Gerasimenko up close.

  • Along with lots of other stuff, it measured the comet's absorption spectrum,

  • the wavelengths of the Sun's light that are absorbed instead of bouncing off the surface.

  • Every substance absorbs light in a unique pattern,

  • so gaps in the reflected spectrum help scientists identify the materials on the surface.

  • There was one gap in the infrared, though, that they couldn't identify.

  • And it wasn't just in one spot, but seemed to be all over the comet.

  • The problem was, identifying unknown spectral features is tricky business,

  • because things like temperature, pressure, and even crystal shape

  • can affect the exact position of a gap.

  • So it's not always straightforward to match a given gap to a specific molecule.

  • And, of course, there's a nearly-infinite supply of potential molecules,

  • so pinpointing the mystery molecule basically came down to guess-and-check in the lab.

  • To do a guess-and-check on Rosetta's observations,

  • researchers had to simulate the frigid surface of a comet deep

  • in the vacuum of space.

  • Once conditions were right, the team used an instrument similar

  • to the one onboard the spacecraft to make a spectrum

  • and look for that mysterious gap.

  • After some experimentation, the researchers found a possible match:

  • salts made from the molecule ammonium.

  • Rosetta had previously detected these nitrogen-based molecules

  • in dust particles ejected from the comet's surface, but now it seems like

  • they might be nearly everywhere.

  • That could mean a lot of nitrogen that wasn't being counted

  • before is actually locked up in ammonium salts, which could go a long way

  • toward settling the mystery of comets' missing nitrogen.

  • And if comets really are rich with nitrogen, that opens up an exciting possibility:

  • maybe comets like 67P helped deliver the ingredients

  • of the air that we are breathing right now.

  • Slime molds might still be this week's MVP in space news,

  • but if comets did deliver the nitrogen in our air,

  • we owe them a lot of credit as well.

  • Thanks for watching this episode of SciShow Space News!

  • While you are here, I want to tell you about our SciShow pin of the month.

  • Every month, we here at SciShow design a new, space-themed pin,

  • and our March pin is of Pioneer 4!

  • It was the first spacecraft from the U.S. to escape the Earth's gravity

  • and enter orbit around the Sun, and the pin was designed

  • by one of our amazing animators here at SciShow.

  • You can only get it this month, so if you're interested,

  • check it out at dftba.com or in the description below.

  • And also, that helps support the show.

  • [♪ OUTRO]

[♪ INTRO]

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