Plus, a camera setup that slows down time. ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏ ͏
February 26, 2026—Why roadkill is a scientific gold mine, a breathtaking look at the chemistry in the Milky Way and an ingenious camera setup that helped physicists slow time. —Emma Gometz, Newsletter Editor | | ALMA(ESO/NAOJ/NRAO)/S. Longmore et al. Stars in inset: ESO/D. Minniti et al. Milky Way: ESO/S. Guisard | | Explore the universe with a subscription to Scientific American. Check out our great February deal! | | A rectangle that, through clever camera tricks, appears to be moving at 80 percent of the speed of light. From "A Snapshot of Relativistic Motion: Visualizing the Terrell-Penrose Effect," by Dominik Hornof et al., in Communications Physics, Vol. 161; May 1, 2025 (CC BY 4.0) | | A strange effect of special relativity called the Terrell-Penrose effect suggests that because light bounces off different parts of an object's 3D shape at slightly different times, the object will appear rotated to an observer at rest. Over 60 years after this theory was published, scientists used a setup that artificially slows down time to observe this effect for the first time. The experiment: Light will take a little longer to arrive at a camera lens from the back of an object than the front. But this difference is too small for human eyes to see. Researchers used a camera (that they bought on Ebay, fun fact) with an exposure time of less than one billionth of a second to try to capture that difference. They placed a objects on a moveable cart and captured photos as lasers illuminated different parts of the objects, all while moving the cart forward in increments. This process created the illusion that a sphere was moving at 99.9 percent of the speed of light because the light was arriving for each photo only 400 picoseconds apart, but the object itself was moving 6 centimeters between each one. The resulting videos showed that the shapes indeed appeared rotated, just as Terrell-Penrose predicts. | | | | |
Why this matters: The experiment proved that physicists can study certain relativistic effects in a lab by artificially reducing the speed of light. The door might now be open to observing time dilation, the relativistic displacement of starlight, or Einstein's thought experiment about lightning strikes seen from a moving train. | | Geologist Tebogo Makhubela works in the Cradle of Humankind—a network of limestone caves that has the world's highest concentration of ancient human fossils. In one cave, he and his team discovered that the bedrock was more than two meters below what they believed to be the cave floor. The excavation revealed "some of the best fossils we've found so far," he says. "By visiting the cave frequently and not taking anything for granted, we uncovered fresh knowledge." Nature | 3 min read
Content courtesy of Nature Briefing. | | It was delightful for me to read the Terrell-Penrose relativity feature, which was about 2,000 words, and come up with a way to distill it into 200 while maintaining accuracy. Theoretical physics can sometimes feel impenetrable, even to devout science lovers like myself. I still get that feeling that maybe physics isn't for me. But pushing past that doubt to immerse myself in special relativity was so rewarding and fun! Have you ever stepped out of your learning comfort zone? How did it feel? | | Send your comments, questions or feedback to newsletters@sciam.com, or just reply to this email. See you tomorrow. —Emma Gometz, Newsletter Editor
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