Aug 12, 2026 04:28 PM
Physicists made 10,000 particles defy Newton’s 3rd law for an hour. Here’s how
https://gizmodo.com/physicists-made-1000...2000797161
EXCERPTS: Some laws of physics are so fundamental that they’ve served as the baseline for science for centuries. But with technological advancements, physicists can—albeit temporarily—create small worlds that evade these laws. And when they do, strange things occur.
In a recent study published in Physical Review Letters, Japanese physicists created a system of more than 10,000 particles that defied Newton’s third law of motion for an hour. According to this law, passive particles exert equal forces on each other, so none can just suddenly push itself along on its own. But in devising this system, the team subjected particles to an alternating electric field that caused passive particles to spontaneously form pairs and “chase” each other in a liquid environment.
“This research demonstrates that the breaking of action-reaction symmetry is a fundamental principle that generates new collective motions and self-organization of matter,” Yutaka Sumino, the study’s co-author and a physicist at the Tokyo University of Science in Japan, said in a statement.
[...] The team suspects that similar interactions take place in biological systems, such as cell colonies and animal groups. If true, the mechanism studied here could even inspire programmable materials and microrobotic systems, it noted. (MORE - missing details)
Why are rivers so mathematical?
https://www.quantamagazine.org/why-are-r...-20260810/
EXCERPT: There’s something appealing about this ubiquitous pattern, so appealing to me personally that I have it tattooed on my forearm: the silhouette of a tree, with leafless branches reaching upward and roots burrowing downward, almost in mirror image. “The shapes of rivers and leaf vasculature and so on — branching networks — you can just about grasp the pattern, but it’s still chaotic, so there’s something fascinating with that,” said Chris Paola, a river scientist at the University of Minnesota.
Systems that branch in this way are “transport networks”: They transport some fluid substance (water, blood, traffic) from every place to a single place (the sea, a heart, a city center). Of the various examples, rivers are especially revealing, I think, since they arise from neither biological evolution nor urban planning, but rather chaotic Earth processes. Yet they obey simple, universal laws.
A discovery about river networks in 2026 reignited my curiosity about their universal form and mathematical nature. These were hot topics in the 1980s and ’90s, when rivers were studied as natural examples of “fractals”: mathematical objects whose features repeat in roughly similar forms at many different scales. Geomorphologists, who specialize in the shape (and continual reshaping) of Earth’s surface, have studied the geometry of river networks far longer, since the late 1800s.
Though many details of river behavior are still being actively studied, the existing mountain of research has yielded explanations that add up to a somewhat satisfying basic understanding. The math is elegant, the geophysics is intuitive, and still my sense of wonder is undiminished.
Every square inch of land on Earth’s surface receives precipitation, and much of it drains out, eventually, to an ocean or lake. Rivers are the drainage system.
In 1957, a U.S. Geological Survey scientist named John Hack discovered the most important law of river networks. In rivers and streams in Virginia and Maryland, Hack measured the length of each stream and the area of the land that slopes toward that stream and therefore drains into it, called its basin or drainage area. What he discovered is now known as Hack’s law: Any stream, from the littlest brook to the mightiest river, has a length that’s proportional to its drainage area raised to the power of 0.6. (In symbolic form: L ~ A0.6.) There’s a bit of variance around that 0.6 value — Earth is, after all, a complicated place — but “the general regularity of the relation is nevertheless remarkable,” Hack wrote. “Stream lengths tend to increase proportionally to the 0.6 power of the drainage area, regardless of the geological or structural characteristics of the area.”
As more and better data has accrued, especially from satellite imagery, Hack’s law has held worldwide. Why this is the case is the essential mystery geomorphologists have grappled with ever since... (MORE - missing details)
https://gizmodo.com/physicists-made-1000...2000797161
EXCERPTS: Some laws of physics are so fundamental that they’ve served as the baseline for science for centuries. But with technological advancements, physicists can—albeit temporarily—create small worlds that evade these laws. And when they do, strange things occur.
In a recent study published in Physical Review Letters, Japanese physicists created a system of more than 10,000 particles that defied Newton’s third law of motion for an hour. According to this law, passive particles exert equal forces on each other, so none can just suddenly push itself along on its own. But in devising this system, the team subjected particles to an alternating electric field that caused passive particles to spontaneously form pairs and “chase” each other in a liquid environment.
“This research demonstrates that the breaking of action-reaction symmetry is a fundamental principle that generates new collective motions and self-organization of matter,” Yutaka Sumino, the study’s co-author and a physicist at the Tokyo University of Science in Japan, said in a statement.
[...] The team suspects that similar interactions take place in biological systems, such as cell colonies and animal groups. If true, the mechanism studied here could even inspire programmable materials and microrobotic systems, it noted. (MORE - missing details)
Why are rivers so mathematical?
https://www.quantamagazine.org/why-are-r...-20260810/
EXCERPT: There’s something appealing about this ubiquitous pattern, so appealing to me personally that I have it tattooed on my forearm: the silhouette of a tree, with leafless branches reaching upward and roots burrowing downward, almost in mirror image. “The shapes of rivers and leaf vasculature and so on — branching networks — you can just about grasp the pattern, but it’s still chaotic, so there’s something fascinating with that,” said Chris Paola, a river scientist at the University of Minnesota.
Systems that branch in this way are “transport networks”: They transport some fluid substance (water, blood, traffic) from every place to a single place (the sea, a heart, a city center). Of the various examples, rivers are especially revealing, I think, since they arise from neither biological evolution nor urban planning, but rather chaotic Earth processes. Yet they obey simple, universal laws.
A discovery about river networks in 2026 reignited my curiosity about their universal form and mathematical nature. These were hot topics in the 1980s and ’90s, when rivers were studied as natural examples of “fractals”: mathematical objects whose features repeat in roughly similar forms at many different scales. Geomorphologists, who specialize in the shape (and continual reshaping) of Earth’s surface, have studied the geometry of river networks far longer, since the late 1800s.
Though many details of river behavior are still being actively studied, the existing mountain of research has yielded explanations that add up to a somewhat satisfying basic understanding. The math is elegant, the geophysics is intuitive, and still my sense of wonder is undiminished.
Every square inch of land on Earth’s surface receives precipitation, and much of it drains out, eventually, to an ocean or lake. Rivers are the drainage system.
In 1957, a U.S. Geological Survey scientist named John Hack discovered the most important law of river networks. In rivers and streams in Virginia and Maryland, Hack measured the length of each stream and the area of the land that slopes toward that stream and therefore drains into it, called its basin or drainage area. What he discovered is now known as Hack’s law: Any stream, from the littlest brook to the mightiest river, has a length that’s proportional to its drainage area raised to the power of 0.6. (In symbolic form: L ~ A0.6.) There’s a bit of variance around that 0.6 value — Earth is, after all, a complicated place — but “the general regularity of the relation is nevertheless remarkable,” Hack wrote. “Stream lengths tend to increase proportionally to the 0.6 power of the drainage area, regardless of the geological or structural characteristics of the area.”
As more and better data has accrued, especially from satellite imagery, Hack’s law has held worldwide. Why this is the case is the essential mystery geomorphologists have grappled with ever since... (MORE - missing details)
