"SOUND BULLETS" COULD BLAST SUBS, CANCER

• An ordinary office toy has inspired a whole new acoustic weapon: "sound bullets."
• Sound bullets could destroy submarines and annihilate tumors.
• The damage such concentrated waves of pressure could create would be devastating.

An old toy has inspired a powerful new weapon that could destroy submarines or annihilate tumors.

Using a modified version of Newton's cradle, a series of stainless steel balls suspended by fishing wire, scientists from the California Institute of Technology have created a powerful weapon for soldiers and doctors known as a "sound bullet."

 

 

"The beauty of this system is that it's just a bunch of ball bearings that we control with weights," said Chiara Daraio, a professor at Cal Tech and co-author of a new Proceedings of the National Academy of Sciencesarticle. Yet by varying the pressure on the ball bearings, the scientists can dramatically amplify and focus sound waves to make them "extremely destructive," according to Daraio.

 

Newton's cradle is an old toy, but the Cal Tech scientists, including Alessandro Spadonia, have adapted it for a hot new field of science known as metamaterials, which includes the Harry Potter-style invisibility cloak. Metamaterials are usually difficult and time-consuming to create.

For their study, the researchers lined up 21 rows of stainless steel ball bearings in an area the size and shape of a laptop computer, with weights attached at the ends to vary the pressure on each row. Then the scientists dropped a small ball about eight inches onto the ball bearings. Using a high-speed camera and a pressure sensitive material, the scientists watched the pressure waves focus on a single spot several inches away from the metamaterial.

The simple set up belies the power of the new metamaterial. Not only did the scientists focus all of the sound waves onto one specific area; they also amplified those waves more than 100 times than what any other metamaterial had previously produced. Those numbers could easily go higher, said Daraio.

The sound waves Daraio and Spadonia manipulated were too high pitched for human ears to detect. Properly adapted to audible sound, the new metamaterial could turn a normal sentence into a split second ear drum rupturing explosion.

If these sound bullets were actual bullets, the metamaterial would be like transforming hot lead projectiles into rocket propelled grenades, all converging on one place at one time. The damage such concentrated waves of pressure could create would be devastating.
 

"Like normal bullets, sound bullets can travel through air. Unlike normal bullets, sound bullets can also easily travel through liquids and solids. Sound bullets could be used by the military to create submarine melting waves of pressure or shock waves powerful enough to destroy caves otherwise untouchable by conventional weapons."

Sound bullets won't just destroy large objects. Daraio says that powerful, focused sound waves could obliterate hard kidney stones or destroy cancerous tumors without any damage to surrounding tissue.

Other, less destructive applications are also possible, said Daraio. Focused sound waves could let engineers see weak bridge supports or future potholes in roads.

Military or medical use of the new metamaterial is still years away, said Daraio. Yet the simplicity and effectiveness of the sound bullet makes it a "significant development," according to L.B. Freund, a professor at Brown University who was not involved in the research.

"People have focused sound waves for a long time," said Freund. "But if you want to do anything with a sound wave, what you can do is determined by the intensity of the sound wave."

Now that Daraio and Spadonia have found a new way to create these powerful sound waves, the potential range of applications for sound bullets is huge.

"The research has opened a new way to developed applied devices, and was done by young researchers in a very creative way," said Freund.

 

Audit finds PG&E smart meters accurate

A smart meter from PG&E

(Credit: PG&E)

An independent review of smart meters installed in Northern California by utility Pacific Gas & Electric found no technical flaws, but a poor roll-out with customers.

The California Public Utilities Commission on Thursday released the evaluation of PG&E's controversial smart-meter program, which was conducted by consulting company The Structure Group.

After PG&E installed two-way meters in Bakersfield, Calif., customers complained that their utility prices shot up, which they blamed on the new meters. Since then, there have been questions over PG&E's handling of the program by regulators and push-back from various communities in its territory.

Earlier this summer, the CPUC contracted with Structure, which tested 750 smart meters and 147 old electromechanical meters. The test found that smart meters reported accurately and that customer billing matched the expected results.

However, Structure identified problems in PG&E's customer service. In reviewing 1,378 customer complaints, Structure said PG&E didn't meet industry standards, leading to people receiving multiple bills or not having questions about smart meters answered.

"The report is encouraging in terms of the performance of actual meter hardware. However, I am very concerned about PG&E's performance in terms of industry best practices and how in some of the best practices areas, PG&E's performance has actually declined,"  

  CPUC Commissioner Dian Grueneich said in a statement.

PG&E's rocky experiences in rolling out smart meters in California has taken on national significance with other utilities trying to learn from PG&E's missteps in introducing the new technology. PG&E's meters allow people to view their energy usage on a daily basis, which helps people better understand their consumption and save energy.

In another case, smart meter installations by utility Oncor in Texas have created complaints from consumers over prices. A review found that that those meters are accurate.

Earlier this year, PG&E released an internal report identifying problems with its smart meter program, which led to a revamp of its customer service operations aimed at better educating customers. About 6.6 million gas and electric meters have been installed so far and the company plans to install 10 million by 2012.

Apart from the accuracy of meters, consumer groups are raising health concerns about the electromagnetic field from smart meters, which transmit information once an hour using a radio frequency.

On its Web site, PG&E says that radio frequency emissions from smart meters are lower than other common electronic devices, such as Wi-Fi routers and cell phones. At a press conference on Thursday, PG&E's Chief Customer Officer Helen Burt echoed those statements and pointed to experts on this question.

A number of cities and towns in PG&E's territory have considered moratoriums on smart meter installations. Senior Vice President of Corporate Affairs Greg Pruett said that PG&E is holding open houses with customers and other groups. "We genuinely believe as we work and talk with customers and show that we are genuinely interested in listening to them...ultimately those cities and counties considering moratoriums will reconsider that desire," he said.