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June 17, 2010 AT 8:34 pm

Experiment finally proves 100-year-old thought experiment is possible


Experiment finally proves 100-year-old thought experiment is possible

A similar machine was first proposed in 1912 by the Polish physicist Marian Smoluchowski. In his thought experiment, he suggested that tiny moving particles could generate enough force to spin a windmill-type paddle. A locking mechanism such as a pawl could prevent backward motion, forcing the wheel to move in the forward direction only.

However, several years later, physicist Richard Feynman argued that, in reality, the bouncing beads would not be capable of doing meaningful work. Feynman showed that, since the entire system operates at the same temperature, a pawl would occasionally slip off the wheel. As a result, the system would generate zero net movement.

Now, physicist Devaraj van der Meer from the University of Twente and his colleagues have demonstrated that such a machine can in fact spin the paddles forward only, generating a positive net movement. The details of their study will be published in an upcoming issue of Physical Review Letters.

Looking somewhat like a high-speed lotto machine, the new system consists of a vigorously shaken platform that causes 2,000 small glass beads to bounce around. When the beads make contact with the vanes of a windmill-like device inside the machine, the vanes move, turning a rod, which rotates a sensor.

Well, that’s finally settled once and for all…


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4 Comments

  1. hmm maybe a nanomachine could use this principal to create energy or do work based on brownian motion

  2. @zool: I believe this was in fact the original proposal, which Feynman suggested would fail if the ratchet was in thermal equilibrium with the particles meant to be driving it. This is not the case for the machine shown in the video – which is probably why it is able to work.

  3. Half way through it starts moving backwards.. Is the pawl failing or is there something else more devious at work.

  4. Any machine that is using heat transfer, is actually using kinetic energy of the particles.

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