Today in Science: Hypervelocity stars from other galaxies

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May 27, 2025—A quantum bubble could destroy the universe. Plus, hypervelocity stars screaming through the galaxy; and how to handle it if your kid is the one who's the bully. —Andrea Gawrylewski, Chief Newsletter Editor TODAY'S NEWS An artist's concept of a hypervelocity star streaking through the Milky Way, surrounded by slower-moving stars. NASA/JPL-Caltech/R. Hurt (Caltech-IPAC) Some stars streaking through the Milky Way at millions of kilometers per hour probably trace back to a supermassive black hole in a neighboring galaxy. | 5 min read Sleep is essential to regulating metabolism, appetite and hormones, research shows. | 6 min read Physician and self-taught epidemiologist Mildred Weeks Wells and her husband, sanitary engineer William Firth Wells, proved that infectious pathogens could spread through the air over long distances. But the scientific establishment ignored their findings for decades. | 34 min listen What to do if your kid is actually the playground bully. | 6 min read Most-clicked yesterday: Surprising Ways That Sunlight Might Heal Autoimmune Disease | 16 min read More News TOP STORIES Unlikely Bubble of Destruction The vacuum of empty space is not exactly empty. Quantum fields, including one called the Higgs field, pervade the vacuum. The Higgs field is special because it controls the mass of all other particles—a lower Higgs value in its quantum field makes it easier for other particles to exist because the energetic barrier is also lowered. The default setting of the Higgs field is like rolling a boulder up a hill: If you nudge the boulder up the hill and then release the boulder, it will roll back down to its resting state.    Jason Drakeford But there might be more to the story. The Higgs field's current value may be a false valley. There may be a second, even deeper valley, so to speak, which may be the true stable resting place for the Higgs field. To access that lower Higgs energy state, the metaphorical boulder could quantum tunnel from a higher-energy setting to a lower-energy one, even if it lacks the energy to climb the hill in between. It's as if it tunneled through the hill rather than traveling over it.    Jason Drakeford What this means: If quantum tunneling revealed the true vacuum, a bubble might form in the Higgs field. This is called vacuum decay. The bubble, if large enough, could expand at roughly the speed of light, erasing the rules of standard physics as it goes and annihilating everything in its path.  What the experts say: Most physicists say the chance of vacuum decay is exceedingly remote, close zero. But it's not zero. One 2024 estimate of the probability of vacuum decay was 10868 (that's a 1 with 868 zeros behind it). "We do have one key piece of evidence that tells us quite a bit: we're alive," writes physicist and science writer Matthew von Hippel. "The simple fact that vacuum decay hasn't occurred already—that the universe has been allowed to carry on for 13.7 billion years without an annihilating bubble sweeping through it" tells us that this process can't be all that likely. Want to dive deeper into the science that interests you? Consider a subscription to Scientific American. Today in Science readers get special discounts! EXPERT PERSPECTIVES Vegetarian and vegan diets promote better health, help mitigate climate change and reduce inhumane factory farming. "Those with greater influence, such as physicians, educators and policy makers, should consider the importance of acting as role models for healthy behaviors themselves as well as advocating for policies that ensure better nutritional access and education for others," writes Sarah C. Hull, an assistant professor of medicine at the Yale School of Medicine. | 4 min read More Opinion

I'm thrilled that we've survived this long without being destroyed by a cosmic bubble! Not only is there always more to learn, so the more days on this planet the better, but our mere existence is helping physicists learn more about the nature of the universe. And this makes us vital on a quantum level.  Send any thoughts or feedback to: newsletters@sciam.com. See you tomorrow!   —Andrea Gawrylewski, Chief Newsletter Editor

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