Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Mysterious quantum forces unraveled

New computational techniques developed at MIT confirmed that the complex quantum effects known as Casimir forces would cause tiny objects with the shapes shown here to repel each other rather than attract. Image courtesy of Alejandro Rodriguez.
New computational techniques developed at MIT confirmed that the complex quantum effects known as Casimir forces would cause tiny objects with the shapes shown here to repel each other rather than attract. Image courtesy of Alejandro Rodriguez.

Abstract:
MIT researchers find a way to calculate the effects of Casimir forces, offering a way to keep micromachines' parts from sticking together.

By Larry Hardesty, MIT News Office

Mysterious quantum forces unraveled

Cambridge, MA | Posted on May 12th, 2010

Discovered in 1948, Casimir forces are complicated quantum forces that affect only objects that are very, very close together. They're so subtle that for most of the 60-odd years since their discovery, engineers have safely ignored them. But in the age of tiny electromechanical devices like the accelerometers in the iPhone or the micromirrors in digital projectors, Casimir forces have emerged as troublemakers, since they can cause micromachines' tiny moving parts to stick together.

MIT researchers have developed a powerful new tool for calculating the effects of Casimir forces, with ramifications for both basic physics and the design of microelectromechanical systems (MEMS). One of the researchers' most recent discoveries using the new tool was a way to arrange tiny objects so that the ordinarily attractive Casimir forces become repulsive. If engineers can design MEMS so that the Casimir forces actually prevent their moving parts from sticking together — rather than causing them to stick — it could cut down substantially on the failure rate of existing MEMS. It could also help enable new, affordable MEMS devices, like tiny medical or scientific sensors, or microfluidics devices that enable hundreds of chemical or biological experiments to be performed in parallel.

Ghostly presence

Quantum mechanics has bequeathed a very weird picture of the universe to modern physicists. One of its features is a cadre of new subatomic particles that are constantly flashing in and out of existence in an almost undetectably short span of time. (The Higgs boson, a theoretically predicted particle that the Large Hadron Collider in Switzerland is trying to detect for the first time, is expected to appear for only a few sextillionths of a second.) There are so many of these transient particles in space — even in a vacuum — moving in so many different directions that the forces they exert generally balance each other out. For most purposes, the particles can be ignored. But when objects get very close together, there's little room for particles to flash into existence between them. Consequently, there are fewer transient particles in between the objects to offset the forces exerted by the transient particles around them, and the difference in pressure ends up pushing the objects toward each other.

In the 1960s, physicists developed a mathematical formula that, in principle, describes the effects of Casimir forces on any number of tiny objects, with any shape. But in the vast majority of cases, that formula remained impossibly hard to solve. "People think that if you have a formula, then you can evaluate it. That's not true at all," says Steven Johnson, an associate professor of applied mathematics, who helped develop the new tools. "There was a formula that was written down by Einstein that describes gravity. They still don't know what all the consequences of this formula are." For decades, the formula for Casimir forces was in the same boat. Physicists could solve it for only a small number of cases, such as that of two parallel plates. Then, in 2006, came a breakthrough: MIT Professor of Physics Mehran Kardar demonstrated a way to solve the formula for a plate and a cylinder.

Calculating the incalculable

In a paper appearing this week in Proceedings of the National Academy of Sciences, Johnson, physics PhD students Alexander McCauley and Alejandro Rodriguez (the paper's lead author), and John Joannopoulos, the Francis Wright Davis Professor of Physics, describe a way to solve Casimir-force equations for any number of objects, with any conceivable shape.

The researchers' insight is that the effects of Casimir forces on objects 100 nanometers apart can be precisely modeled using objects 100,000 times as big, 100,000 times as far apart, immersed in a fluid that conducts electricity. Instead of calculating the forces exerted by tiny particles flashing into existence around the tiny objects, the researchers calculate the strength of an electromagnetic field at various points around the much larger ones. In their paper, they prove that these computations are mathematically equivalent.

For objects with odd shapes, calculating electromagnetic-field strength in a conducting fluid is still fairly complicated. But it's eminently feasible using off-the-shelf engineering software.

"Analytically," says Diego Dalvit, a specialist in Casimir forces at the Los Alamos National Laboratory, "it's almost impossible to do exact calculations of the Casimir force, unless you have some very special geometries." With the MIT researchers' technique, however, "in principle, you can tackle any geometry. And this is useful. Very useful."

Since Casimir forces can cause the moving parts of MEMS to stick together, Dalvit says, "One of the holy grails in Casimir physics is to find geometries where you can get repulsion" rather than attraction. And that's exactly what the new techniques allowed the MIT researchers to do. In a separate paper published in March, physicist Michael Levin of Harvard University's Society of Fellows, together with the MIT researchers, described the first arrangement of materials that enable Casimir forces to cause repulsion in a vacuum.

Dalvit points out, however, that physicists using the new technique must still rely on intuition when devising systems of tiny objects with useful properties. "Once you have an intuition of what geometries will cause repulsion, then the [technique] can tell you whether there is repulsion or not," Dalvit says. But by themselves, the tools cannot identify geometries that cause repulsion.

####

For more information, please click here

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Microfluidics/Nanofluidics

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

News and information

New synthesis method may shape future of nanostructures, clean energy: Findings advance efficient solar spliting of water into hydrogen fuel September 2nd, 2014

Accounting for Biological Aggregation in Heating and Imaging of Magnetic Nanoparticles September 2nd, 2014

Engineers develop new sensor to detect tiny individual nanoparticles September 2nd, 2014

Future solar panels September 2nd, 2014

Possible Futures

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Academic/Education

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

SEMATECH and Newly Merged SUNY CNSE/SUNYIT Launch New Patterning Center to Further Advance Materials Development: Center to Provide Access to Critical Tools that Support Semiconductor Technology Node Development August 7th, 2014

Oxford Instruments Asylum Research and the Center for Nanoscale Systems at Harvard University Present a Workshop on AFM Nanomechanical and Nanoelectrical Characterization, Aug. 21-22 August 6th, 2014

MEMS

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Leti to Present Technological Platforms Targeting Industry’s Needs for the Future at Semicon West Workshop: Presentation at STS Session to Focus on Leti Advanced Lithography Programs for 1x Nodes and on Silicon Photonics at TechXPot June 25th, 2014

Mirrorcle Technologies Opens New Company Headquarters May 27th, 2014

Ziptronix and EV Group Demonstrate Submicron Accuracies for Wafer-to-Wafer Hybrid Bonding: Enables Fine-Pitch Connections for 3D Applications, Including Image Sensors, Memory and 3D SoCs May 27th, 2014

Nanomedicine

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

Accounting for Biological Aggregation in Heating and Imaging of Magnetic Nanoparticles September 2nd, 2014

Nano-forests to reveal secrets of cells September 2nd, 2014

Nanoscale assembly line August 29th, 2014

Sensors

New synthesis method may shape future of nanostructures, clean energy: Findings advance efficient solar spliting of water into hydrogen fuel September 2nd, 2014

Engineers develop new sensor to detect tiny individual nanoparticles September 2nd, 2014

Copper shines as flexible conductor August 29th, 2014

Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices August 28th, 2014

Discoveries

Secure Computing for the ‘Everyman': Quantum computing goes to market in tech transfer agreement with Allied Minds September 2nd, 2014

Cool Calculations for Cold Atoms: New theory of universal three-body encounters September 2nd, 2014

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

Future solar panels September 2nd, 2014

Announcements

New synthesis method may shape future of nanostructures, clean energy: Findings advance efficient solar spliting of water into hydrogen fuel September 2nd, 2014

Accounting for Biological Aggregation in Heating and Imaging of Magnetic Nanoparticles September 2nd, 2014

Engineers develop new sensor to detect tiny individual nanoparticles September 2nd, 2014

Future solar panels September 2nd, 2014

Nanobiotechnology

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

Nano-forests to reveal secrets of cells September 2nd, 2014

Nanoscale assembly line August 29th, 2014

The channel that relaxes DNA: Relaxing DNA strands by using nano-channels: Instructions for use August 20th, 2014

Quantum nanoscience

Cool Calculations for Cold Atoms: New theory of universal three-body encounters September 2nd, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

X-ray Laser Probes Tiny Quantum Tornadoes in Superfluid Droplets: SLAC Experiment Reveals Mysterious Order in Liquid Helium August 25th, 2014

Rice physicist emerges as leader in quantum materials research: Nevidomskyy wins both NSF CAREER Award and Cottrell Scholar Award August 20th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE