Milky Way–Andromeda Collision Is in Doubt, North Atlantic Ocean Heat Surged, and Worms Build Towers todayheadline

New Doubts about Milky Way–Andromeda Collision, Explanation of 2023 Marine Heat Wave and Worms That Build Towers

By Rachel Feltman, Naeem Amarsy & Fonda Mwangi

Rachel Feltman: Happy Monday, listeners! For Scientific American’s Science Quickly, I’m Rachel Feltman. Let’s kick off the week with a quick roundup of some science news you may have missed.

You’ve probably heard that our galaxy, the Milky Way, is doomed to collide with the neighboring Andromeda galaxy sometime around 5 billion years from now. But according to new research, maybe we shouldn’t count on this multigalactic merger deal going through.

In a study published last Monday in Nature Astronomy, researchers who analyzed data from the European Space Agency’s Gaia space telescope and NASA’s Hubble say the event is more of a coin flip than a given: the team’s 100,000 computer simulations suggest there’s just about a 50/50 chance of the two galaxies colliding within the next 10 billion years or so. When you look at the next 4 to 5 billion years, that chance drops down to around 2%.

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In other space news, scientists are buzzing about a tiny star that punches way above its weight. TOI-6894 is a red dwarf that’s roughly 20% as massive as our sun. But in a study published last Wednesday in Nature Astronomy, researchers say they’ve spotted the signature of a giant planet orbiting the little guy. The planet, called TOI-6894b, is described as a low-density gas giant—it is a little bigger than Saturn, but only has around half as much mass. Astronomers say the presence of a gas giant around such a small star is so surprising that it challenges the most widely accepted theory of planet formation. That theory, called core accretion, suggests that giant planets are born when their solid cores get massive enough to start pulling in lots of gas. Smaller stars generally lack enough gas and dust in their protoplanetary discs to allow for such a process, but this red dwarf ended up with a gas giant anyhow. Because red dwarf stars are super common in our galaxy, this could mean gas giants are more plentiful than we thought. The researchers will use the James Webb Space Telescope to study the planet’s atmosphere, which should provide more clues about its formation.

Now let’s move on to some environmental news. Back in the summer of 2023 an extreme marine heat wave hit the North Atlantic Ocean, affecting water temperatures from Greenland to the Sahara and all the way over to the Americas. A study published last Wednesday in Nature aimed to explain why. The researchers say the summer temperature surge was equivalent to around 20 years of typical warming in the North Atlantic. While climate change, of course, played a role, the new study pinpoints some other factors that made water temperatures particularly hot that summer. For starters, in June and July of that year, the winds over the North Atlantic were weaker than at any other period on record, which meant less churning to mix sun-warmed surface waters. As a result heat was more concentrated and rose more quickly.

The researchers also note that it’s possible a reduction in sulphur emissions led to fewer clouds in some areas, so more sunlight hit the water. But the scientists were quick to add that weak wind was the primary driver—and that climate change is likely to make things worse. Reducing pollution from the atmosphere, generally speaking, remains a great thing to do. In a news release, the study’s lead author noted that if we don’t cut down our fossil fuel emissions, extreme marine heat waves like the one we saw in 2023 will only get more common and more intense. And that’s bad news for everyone: warm water releases heat into the atmosphere, contributing to heat waves and severe rainstorms. Warmer oceans also mean more hurricanes. And higher water temperatures are tied to increases in coral bleaching as well.

But another study, published last Thursday in Frontiers in Marine Science, offers some hope for ailing coral—not from bleaching but from a disease that can be just as devastating to a reef.

Stony coral tissue loss disease, or SCTLD, was first identified off the coast of Florida just over a decade ago and has now been spotted on reefs throughout the Caribbean. More than 20 species of coral can catch it. SCTLD quickly destroys a coral’s soft tissue, with some species dying within weeks of symptoms appearing. It’s not clear exactly what causes SCTLD, but it seems likely that bacteria at least play a part because treating affected corals with an antibiotic paste has been shown to help them survive.

The issue with this treatment is that it’s a temporary fix, and it opens the door for the potential evolution of a resistant strain of whatever bacterium is involved. This new study reports on the promising results of treating coral with probiotics instead.

Corals have microbiomes just like we do, and a boost of good bacteria seems to help keep them healthy. The researchers behind the new study started by testing more than 200 strains of bacteria from disease-resistant corals and ultimately focusing on a particularly promising strain from great star corals in the lab. In 2020 the scientists took their experiment into the ocean, applying a solution of seawater and probiotics to a Florida reef impacted by SCTLD and using weighted plastic bags to create a sort of in-ocean aquarium that kept the treatment from floating away. After two and a half years, the probiotics seemed to be preventing the spread of SCTLD without causing any other disruptions to the reefs’ microbiome. More research is needed to see how this treatment might impact coral in other regions, but probiotics could prove to be an important tool for fighting this devastating disease.

We’ll wrap up today’s episode with something fun, if maybe also a little bit creepy: an act of “collective hitchhiking” featuring a living tower of worms.

Nematodes are tiny worms that you probably don’t spend much time thinking about, but they’re actually the most abundant animals on Earth, making up an estimated four-fifths of all animal life on our planet. According to a study published last Thursday in Current Biology, these creatures might sometimes use their vast numbers to make up for their miniscule size.

Individual nematodes will sometimes stand on their tails and wave around to try to hitch a ride on a passing animal. Scientists have long suspected that they can also link together to form multi-worm “towers” to increase their height, but this had only ever been observed in a lab setting. In the new study scientists describe seeing some of these waving worm towers inside decaying apples and pears found in the dirt of orchards.

Further observations proved that, far from a chaotic pile of worms, these structures reflect the kind of superorganism behavior we see in slime molds and fire ants. While many species of nematode could be found in each piece of rotting fruit, the towers only consisted of members of the same species. Once in place, the nematodes would wave in unison as if they were one giant worm. Experiments in the lab showed that nematodes could self-assemble in just two hours and remain stable for more than 12. They could even create little arms with which to explore the space and build bridges to cross gaps to new locations. So the next time you’re struggling with a group project at school or work, just remind yourself that even nematodes can figure out how to work together.

That’s all for this week’s science news roundup. We’ll be back on Wednesday.

Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi, Kelso Harper, Naeem Amarsy and Jeff DelViscio. Shayna Posses and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news.

For Scientific American, this is Rachel Feltman. Have a great week!