Tuesday, March 03, 2015

The Unnatural Properties of a Designer "Sponge"

A rubber sheet with weird properties, held by Bastiaan Florijn of Leiden University. Credit: Mike Lucibella
Nearly 10,000 physicists have descended on San Antonio this week for the annual American Physical Society March Meeting, the largest meeting of professional physicists in the world. The sheer scale of simultaneous talks is overwhelming and the convention center is so vast that many people are actually running from talk to talk.

Bastiaan Florijn at APS March Meeting.
Credit: Mike Lucibella
In this maze of new developments, I caught up with Bastiaan Florijn, a physicist at Leiden University in the final year of his PhD. He and his group led by Martin van Hecke have made something that looks like an extra-holey pink sponge but is in fact the first programmable "metamaterial".

A metamaterial is something that is carefully engineered to have unique properties that are not often found in nature. This could be a naturally-brittle material that is built, folded, or cut in such a way to become elastic. Or a sound-absorbing material that is tuned to only absorb kinds of sounds. The key idea is that it is the structure, not the type of material (e.g. rubber, metal, or wood) that controls the mechanical properties of the material.

In Florijn's case, he wanted to make a material that could buckle under pressure in a controlled way, and bounce back to its original shape afterwards. This could be useful in creating car bumpers that squish and absorb energy in a collision, but can return to their pristine state afterwards.

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Friday, February 27, 2015

Building An Earthquake Resistant Home

Earthquakes are unexpected, terrifying and can hit at any time, causing major destruction and even death.

More than 1.3 million earthquakes of varying magnitudes rattle our world each year destroying homes and changing the landscape of cities around the world.

"I saw my city destroyed because of this earthquake," said Eduardo Miranda, a structural engineer at Stanford University in California.

Miranda was in Mexico City when a magnitude 8.1 earthquake hit.

"I've seen firsthand the impact big earthquakes could have," he said. "There were more than 10,000 people killed and hundreds of buildings collapsed."




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Thursday, February 26, 2015

The First Colorblind, Ultrathin Lens Is Developed

A new kind of flat, ultrathin lens has been created by Harvard physicists that can focus multiple colors of light in the same spot.

Traditional lenses and other optical devices focus different colors in different places, requiring multiple lenses to create a sharp, multicolor image. By developing one flat "colorblind" lens that can focus many colors in the same way, the researchers hope their device can be used in fields where miniature, low-cost lenses are key, such as photography, optical communication, astronomy, and microscopy.

An argon laser beam of multiple colors (blues and greens) is reflected off of a diffraction grating mirror. Each color follows a different path after reflection, something that Capasso's group is working to avoid.
Credit: adapted from Lazord00d via Wikimedia commons

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Wednesday, February 25, 2015

Podcast: The Physics Behind the Silver Screen



Have you ever sat in a movie theater and wondered how the projector gets an image onto the screen? It turns out there's a lot of physics that goes into it, whether you're using a traditional film projector, digital, or the latest laser technology. On today's podcast, we take a look at the physics of the movie projector and how changing technologies are affecting the movie-going experience.

A DLP chip — a component of digital projectors.
Image Credit: Andrew Hitchcock via Wikimedia Commons


First we check in with Steve Seid, who, until his retirement this past December, had been the Video Curator at Berkeley's Pacific Film Archive for 26 years. We also chat with Ryan Hufford, a Senior Systems Engineer at Vulcan, Inc., who recently installed a brand new laser projector at Seattle's Cinerama Theatre. After many decades of relatively stable projector technology, we're suddenly in a "tumult of innovation" as Seid calls it, and prospects for the future of movie-watching are bright and varied.
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Tuesday, February 24, 2015

Hunting Language Sounds Through History

All languages evolve over time, but finding how and when certain changes happen is a daunting task for linguists faced with an overwhelming amount of data. Now researchers from the U.S. and the U.K. have used a statistical technique popular in physics to let the computer do the hard work. Their research traces the pronunciation of words over thousands of years, with more precision than ever before.

Language tree of European and Uralic language evolution. Not associated with the work by Mark Pagel and Tanmoy Bhattacharya. Credit: Illustration by Minna Sundberg. Available via creative commons from flickr.

Led by Mark Pagel from the University of Reading and Tanmoy Bhattacharya from the Santa Fe Institute, this work was published last month in the journal Current Biology.

Language shifts often occur because the way a vowel or consonant is pronounced changes in many different words at once. For example, early Germanic languages used a p sound in words like "pater" or "pedis", but this later changed to an f sound creating the more familiar words "father" and "foot".

A sound change in many different words at the same time is known as "concerted evolution", and allows linguists to track the history and relationship of languages. From this type of study, a language tree can be constructed, similar to a family tree in genealogy.

But for researchers, finding these language shifts in words can be a very tedious task, made more complex if individual sounds within words are studied.

"Computers so far have mainly used the presence or absence of words with a common origin in various languages to stitch together trees that describe the descent of the various languages from a common ancestor," said Bhattacharya in a Santa Fe Institute press release. "This has left out the vastly richer data residing in sounds".

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Monday, February 23, 2015

A More Finely Tuned Universe

Could life as we know it have developed if fundamental physics constants were different?

Originally published: Feb 20 2015 - 12:15pm, Inside Science News Service
By: Gabriel Popkin, Contributor

(Inside Science) -- For all the progress physicists have made in figuring out the universe, they still don't know some pretty basic things. Why, for example, do fundamental particles possess the specific values of mass that they have? Presently, physicists have no explanation for this and similar questions.

They do know something pretty significant, however. If the masses of particles or the values of fundamental constants were much different from what physicists have measured, carbon-based intelligent beings might not be here to measure them, because fundamental particles might not assemble into stable atoms, atoms might not form rocky planets and dying stars might not produce the chemical elements we find in our bodies.

These observations have led some physicists to describe the universe as "fine-tuned" for carbon-based life. Imagine the universe is like a machine with dials used to set the properties of each important piece -- from the masses of the constituents of protons and neutrons to the rate of expansion of the universe. If many combinations of dial settings yield conditions in which complex life can evolve, physicists would say the universe is not fine-tuned. But if some of the dials have to be set very precisely to values that are not readily explained by theory, physicists would consider these parameters to be fine-tuned.

The Eagle Nebula’s Pillars of Creation as seen from NASA/ESA Hubble Space Telescope
Image credit: NASA, ESA/Hubble and the Hubble Heritage Team
Rights information: http://bit.ly/17AlyuK

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Friday, February 20, 2015

Zealots Help Sway Popular Opinions

Enthusiasts can greatly influence the adoption of new ideas.

Image credit: Gabriel Saldana via Flickr | http://bit.ly/1E9IjCQ
Rights information:http://bit.ly/1dWcOPS
Opinions rarely form in a vacuum. People are heavily influenced by the opinions of others in their social networks, whether they be real or virtual. Some people are not open to new ideas. These are the zealots, who proselytize an opinion -- the superiority of Apple products, for example, or skepticism about climate change -- in the hopes of convincing others, while stubbornly resisting being influenced themselves.

Researchers studying the evolution of sentiments in a society, a field called opinion dynamics, have long been interested in the effects of zealots on the dissemination and adoption of ideas. One way to study this is to use a mathematical model such as the so-called naming game.

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Thursday, February 19, 2015

Controlling Water Drops on the Space Station with Legos and Electricity

What do you do when you've got free time on the International Space Station and a bunch of legos? Build a Van de Graaff generator out of lego bricks, a rubber band, and a drill of course! In 2012 astronaut Don Pettit did exactly this when he was on board the ISS; he then searched around for objects to electrify, little knowing his fun experiments would lead to a full research paper on charged water droplets (published this month in the Physical Review Letters journal) and some very real-world applications.

International Space Station in 2010. Credit: NASA / public domain
"We work about 14 hours a day and when you're not working, you can do whatever you want to," said Pettit about his astronaut duties on the ISS. "I would do science experiments of my own design on things that just tickled my imagination, basically for no more reason than I was there and I could."

Pettit threw away the instruction book of an educational lego kit and put together a simple drill-powered Van de Graaff generator, which collects charge built up from a spinning rubber band. "It was real fun and it was a real piece of scientific equipment," said Pettit. "This thing would throw 80 millimeter sparks." Pettit documented his generator in a video for Physics Central's Science Off The Sphere back in 2012.


"Once I had the Van de Graaff generator, it became a question of what can I do with a Van de Graaff generator in a weightless environment?" said Pettit. "I'd put our deionized water on the collector of the generator and you could see all these delightful charge effects on the water."

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Wednesday, February 18, 2015

Podcast: The Impending Intergalactic Cloud Collision



Not too far away, there's a giant gas cloud drifting towards the Milky Way galaxy. Known as the Smith Cloud and made up mostly of hydrogen, it should merge with our home system in about 30 million years. On this week's podcast, I spoke with Jay Lockman, the lead scientist at the NRAO's Green Bank Telescope in West Virginia who told me about this mysterious object.

A false-color image of the Smith Cloud, showing it's comet-like appearance.
Image: NRAO/AUI/NSF


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Monday, February 16, 2015

Science Dispatches from San Jose

San Jose, California was the place to be for science this week. The American Association for the Advancement of Science held its annual meeting there, featuring talks and lectures and exhibits from across all fields of science. There was even ice cream.



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