Physics Buzz

When Fan Xu needs a break from his mechanics of soft materials research at Fudan University, he likes to visit the campus’s lotus pool for a calming breath of fresh air. When you’re a physicist, though, sometimes a short break can backfire—in Xu’s case, leading to an 18-month study of thin biological tissue. It all started when he observed something curious in the growth of the lotus plants. “I noticed that the leaves had different shapes depending on whether they had a water foundation,” he says. “The lotus leaves floating on the water had a flat shape with wrinkles around the margin, while for leaves growing up above the water they have a global deformation, like a cone shape.” While there are a host of factors influencing the growth of a lotus leaf, including genes, Xu wondered what effect the water substrate had on leaf growth and whether he could explain the various shapes from a physics perspective. Figure 1 . The Xi Garden at Fudan University boasts a number of water lil

On garbage day, blue trash cans line the streets of my neighborhood. Trucks collect the contents¬–bags of spoiled food, discarded packaging, and once-treasured objects. The trash eventually settles in landfills or is incinerated, but to most of us, it’s gone as soon as the truck rounds the corner. But there are no garbage routes in space. At least not yet. Russia launched the first human-made satellite into space in the fall of 1957. Since then, we’ve amassed hundreds of millions of pieces of space junk. They range from flecks of paint to large, defunct satellites and can travel at speeds up to 17,500 mph. Computer-generated image representing space debris from the perspective of high Earth orbit. Dots represent the location of an object and are not to scale. The two main debris fields are the ring of objects in geosynchronous Earth orbit (GEO) and the cloud of objects in low Earth orbit (LEO). Credit: NASA. Even a chip of paint traveling at 17,500 mph can se

Put on your headphones, crank up your speakers, and hit play: Pete Townshend’s gritty guitar style may have helped define The Who’s sound, but it’s also the inspiration behind a recent Physical Review Letter . The wailing—even screeching—so characteristic of his style is a prime example of guitar feedback, which occurs when the amplifier’s noise makes it back to the guitar and causes the strings to vibrate. These vibrations are picked up by the microphone and amplified in turn until the note reaches ear-splitting levels—perfect for a chaotic rock concert: Not all feedback is deafening, though. Those signs that flash your speed disapprovingly use feedback to encourage you to ease off the gas, and your heating system regulates itself the same way. Without feedback, cells could not maintain homeostasis — but the principle also has f rightening implications for climate change Regardless of the specifics, all feedback loops follow the same general pattern. It all starts when a

Ah, spaghetti. There’s just something about the loveable dish that’s captured popular attention for decades, from the BBC’s spaghetti tree hoax to that famous kiss scene in Lady and the Tramp. But it’s also kept researchers busy with projects like feeding pasta through an MRI machine to see how it cooks, explaining why you just can’t keep sauce from covering your shirt, and building the ultimate spaghetti-snapping machine. Third-year graduate student Nathaniel Goldberg is one of the latest researchers to try his hand at the floppy dish. He works in Dr. Oliver O’Reilly’s lab at the University of California Berkeley, which models all kinds of things—from plant stems to shoelaces —as slender rods, a one-dimensional mathematical construction. Maybe it’s a case of having a hammer and only seeing nails, but Goldberg can’t help but think about rods anywhere he looks. “The other day, I was looking out the window at all the palm trees and started thinking, Wow, that would be fun to model,