Physics Buzz

In 2008, the European satellite PAMELA detected a surprisingly large concentration of high energy positrons above our atmosphere. The presence of so many positrons, the anti-matter counterpart of electrons, goes against theoretical predictions but has been verified by other detectors. In new research published earlier this month by the AAAS journal Science, a team of researchers from Germany, Mexico, Poland, and the United States now cast doubt on one of the leading explanations for the mysterious excess—leaving its origin still unknown.

What really determines clouds and rain? Why does burning rubber smoke so heavily? What gives sparkling wines their distinct and lively aroma? The answer to all of these questions leads back to bubbles, according to Alfonso Gañán-Calvo from the University of Seville in Spain. When small bubbles on the surface of a liquid burst, they often send tiny droplets of the liquid flying into the air. These tiny droplets spread out through the air and, if they contain solutes or particles, the relics after liquid evaporation become seeds for clouds, far-reaching scents, or heavy smoke.

“Light is intriguing and still full of surprises, even though we use it every day to perceive the world around us,” says Lorenzo De Angelis, a PhD student at the Kavli institute of Nanoscience in Delft, the Netherlands. He speaks from experience. An unexpected aspect of light’s behavior was just uncovered by a team including De Angelis, Prof. Kobus Kuipers, and collaborators from Delft and the University of St. Andrews in the United Kingdom. Their work originated at AMOLF in Amsterdam and was published this week in the American Physical Society’s journal Physical Review Letters.

The leverlike guitar accessory known as a whammy bar is best used to bend and distort a single note—think Jimi Hendrix's famous rendition of the Star Spangled Banner from Woodstock 1969. But it doesn't sound very nice if used when playing multiple strings simultaneously, such as when strumming a chord. To solve this problem, a researcher from the U.K. has engineered new guitar strings that respond tunefully and as a group when you use a whammy bar.

Lightning can be a destructive force of nature, but it’s not immune to human influence. In fact, new research suggests that the exhaust from ships transporting oil, coffee, and probably this holiday season’s most popular gifts is intensifying thunderstorms and increasing the number of lightning strikes along some of the busiest shipping lanes in the world. Conducted by Joel Thornton, Robert Holzworth, and Todd Mitchell from the University of Washington and Katrina Virts from NASA Marshall Space Flight Center, the research was published earlier this fall in the American Geophysical Union’s journal Geophysical Research Letters.

Studying physics and learning about the laws that define our universe is usually its own reward—but sometimes it's nice to have other rewards, too. That's why we're excited to share the news about Physics in Advent: an opportunity to learn physics via hands-on experiments all throughout the month of December, and also to win books, electronics, science kits—and, for one lucky American student, a trip to Europe!

There’s a lot of room between the tiny world of the nanoscale and the grand scale over which we usually talk about Einstein’s general theory of relativity. Although the arenas seem vastly different, we may soon be able to observe the phenomena of general relativity in nano-sized metals.

Last week, a reader named Nabilah wrote in to ask:
Electrons carry charge, but I've been told that electrons in a DC circuit actually move slower than a snail, and in an AC circuit, they don't move at all, just shifting to and fro. Then how does that make a lightbulb light up?