Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Classical thought experiment brought to life in granular gas

Figure 1. Smoluchowski's thought experiment 
Smoluchowski's thought experiment with the vanes on the right, the cog on the left and in the middle a pulley with a weight. Inset: our granular demonstration experiment.
Figure 1. Smoluchowski's thought experiment Smoluchowski's thought experiment with the vanes on the right, the cog on the left and in the middle a pulley with a weight. Inset: our granular demonstration experiment.

Abstract:
Researchers from the University of Twente, the University of Patras in Greece and the Foundation for Fundamental Research on Matter (FOM) have for the first time experimentally realised, almost a century later, an idea dating from 1912. In that year the physicist Smoluchowski devised a prototype for an engine at the molecular scale in which he thought he could ingeniously convert Brownian motion into work. The team of scientists have now successfully constructed this device at the much larger scale of a granular gas. Moreover, they have shown that an intriguing exchange takes place between the vanes of the engine and the granular gas: once the vanes have started rotating, they in turn induce a rotating motion in the gas, a so-called convection roll. This reinforces the movement of the device and allows for a virtually continuous rotation. FOM PhD student Peter Eshuis and his colleagues published their results on 16 June 2010 online in the renowned journal Physical Review Letters.

Classical thought experiment brought to life in granular gas

The Netherlands | Posted on June 18th, 2010

Molecular motors, such as those responsible for tensing and relaxing your muscles, move in a strange manner: they propel themselves forwards despite - or thanks to - a continuous bombardment of the randomly moving molecules in their surroundings. This random movement is called Brownian motion and a well-constructed motor at the nanoscale actually makes use of this to generate a directed movement (and therefore work).

The device introduced by the physicist Marian Smoluchowski in 1912, as a thought experiment, is a classical example of such a motor (see Figure 1). It consists of a series of vanes mounted on an axis, which are set in motion under the influence of the molecular bombardment. As this motion would take place in both rotational directions, Smoluchowski devised a second element, an asymmetrical cog. This would ensure that the axis could only rotate in a single direction and could therefore perform work, for example by pulling a small weight up. However, in 1963 Richard Feynman demonstrated that the second law of thermodynamics would prevent the device from working in a system that was in a state of thermal equilibrium and with this, the thought experiment appeared to have been consigned to the waste bin.

Yet the objection formulated by Feynman does not apply to a system far removed from a thermal equilibrium, such as a granular gas. Researchers from the University of Twente, the University of Patras and FOM have now successfully demonstrated that Smoluchowski's thought experiment works superbly in this environment.

Brownian motion

Imagine that you are driving your car through a storm with hailstones as big as footballs. Every time that such a hailstone hits you, the impact propels you forwards, backwards or sideways, with the result that you stagger forwards across the road like a drunkard. A far-fetched example? Not on the molecular scale: there (due to the continual collisions with the surrounding molecules) all particles move in this manner, a phenomenon termed Brownian motion.

Granular gas

If a container filled with beads is vigorously vibrated on top of a shaking device, the beads move so fast that a gaseous state of rapidly moving beads arises. In many ways this state is similar to the molecular gaseous state. However, there exists one major difference with a molecular gas: when you stop shaking, the beads will lose their energy in a very short space of time and come to lie motionless on the bottom of the container. This happens because a bit of energy is lost in each collision between two beads. A constant supply of energy is therefore needed to maintain the granular gaseous state and this explains why this system remains far from thermal equilibrium.

Reference

Peter Eshuis, Ko van der Weele, Detlef Lohse and Devaraj van der Meer, Experimental Realization of a Rotational Ratchet in a Granular Gas, Phys. Rev. Lett. 104, 248001 (2010).

Movies of the experiment: stilton.tnw.utwente.nl/dryquicksand/ratchet/ratchet.html

####

For more information, please click here

Contacts:
Devaraj van der Meer or Detlef Lohse, tel. (053) 489 80 76

Copyright © University of Twente

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

News and information

MRI, on a molecular scale: Researchers develop system that could one day peer into the atomic structure of individual molecules April 20th, 2014

Iranian Researchers Present New Model to Strengthen Superconductivity at Higher Temperatures April 19th, 2014

Iranian Researchers Produce New Anti-Cancer Drug from Turmeric April 19th, 2014

Innovative strategy to facilitate organ repair April 18th, 2014

Academic/Education

Director Wally Pfister joins UC Berkeley neuroengineers to discuss the science behind ‘Transcendence’ April 7th, 2014

First annual science week highlights STEM pipeline and partnerships: UB, SUNY Buffalo State and ECC team up with the City of Buffalo and its schools for April 7-11 events April 3rd, 2014

Global 450 consortium announces new general manager of internal operations: TSMC’s Cheng-Chung Chien Receives Unanimous Support, Brings History of Innovation and Efficiency to Global Consortium of Companies Driving Industry Transition to 450mm Wafer Technology March 26th, 2014

NanoTecNexus to Host "Chemistry of Wine" Fundraiser in Support of STEM Education - Collaborations Key to Success - March 20th, 2014

Molecular Machines

Structural Insights into the Inner Workings of a Viral Nanomachine April 3rd, 2014

Big data tackles tiny molecular machines:Rice University technique able to analyze conformations of complex molecular machines March 14th, 2014

Advantages emerge in using nanostructured material in the forging process of mechanical components February 28th, 2014

Nanomotors are controlled, for the first time, inside living cells February 10th, 2014

Announcements

MRI, on a molecular scale: Researchers develop system that could one day peer into the atomic structure of individual molecules April 20th, 2014

Iranian Researchers Present New Model to Strengthen Superconductivity at Higher Temperatures April 19th, 2014

Iranian Researchers Produce New Anti-Cancer Drug from Turmeric April 19th, 2014

Innovative strategy to facilitate organ repair April 18th, 2014

Research partnerships

Novel stapled peptide nanoparticle combination prevents RSV infection, study finds April 17th, 2014

Scientists Capture Ultrafast Snapshots of Light-Driven Superconductivity: X-rays reveal how rapidly vanishing 'charge stripes' may be behind laser-induced high-temperature superconductivity April 16th, 2014

Scalable CVD process for making 2-D molybdenum diselenide: Rice, NTU scientists unveil CVD production for coveted 2-D semiconductor April 8th, 2014

Carbon nanotubes grow in combustion flames April 1st, 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