Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosunís ALD solutions enable novel high-speed memories June 27th, 2017

Academic/Education

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

The 2017 Winners for Generation Nano June 8th, 2017

MIT Energy Initiative awards 10 seed fund grants for early-stage energy research May 4th, 2017

Bar-Ilan University to set up quantum research center May 1st, 2017

Molecular Machines

First 3-D observation of nanomachines working inside cells: Researchers headed by IRB Barcelona combine genetic engineering, super-resolution microscopy and biocomputation to allow them to see in 3-D the protein machinery inside living cells January 27th, 2017

Micro-bubbles make big impact: Research team develops new ultrasound-powered actuator to develop micro robot November 25th, 2016

Scientists come up with light-driven motors to power nanorobots of the future: Researchers from Russia and Ukraine propose a nanosized motor controlled by a laser with potential applications across the natural sciences and medicine November 11th, 2016

HKU chemists develop world's first light-seeking synthetic Nanorobot November 9th, 2016

Announcements

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Nanometrics to Participate in the 9th Annual CEO Investor Summit 2017: Accredited investor and publishing research analyst event held concurrently with SEMICON West and Intersolar 2017 in San Francisco June 27th, 2017

NMRC, University of Nottingham chooses the Quorum Q150 coater for its reliable and reproducible film thickness when coating samples with iridium June 27th, 2017

Picosunís ALD solutions enable novel high-speed memories June 27th, 2017

Research partnerships

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Research accelerates quest for quicker, longer-lasting electronics: UC Riverside-led research makes topological insulators magnetic well above room temperatures June 25th, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Alloying materials of different structures offers new tool for controlling properties June 19th, 2017

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