Criticism of Feynman's analysis of the ratchet as an engine

American Journal of Physics

Volumn 64, Issue 9, 1996, Pages 1125-1130

  Parrondo, Juan M R ^a   Español, Pep ^b  

^a UNIVERSIDAD COMPLUTENSE DE MADRID   (Spain)

^b UNIVERSIDAD NACIONAL DE EDUCACIÓN A DISTANCIA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0002231777     PISSN: 00029505     EISSN: None     Source Type: Journal    
DOI: 10.1119/1.18393     Document Type: Article

References (13)

1. R. P. Feynman, R. B. Leighton, and M. Sands, The Feynman Lectures on Physics (Addison Wesley, Reading, MA, 1963), Vol. 1, pp. 46.1-46.9.
2. In fact, engines of this type have actually been built since the 18th century - and they work! - either by using fluctuations of the room temperature, the atmospheric pressure, or the orientation of our wrist in ordinary automatic watches. These engines are not in contradiction with the second principle, for they make use of macroscopic fluctuations - not thermal fluctuations - such as those in the room temperature due to variations of sunlight, for instance.
3. H. S. Leff and A. R. Rex, Maxwell's Demon. Entropy, Information, Computing (Princeton U.P., Princeton, 1990), p. 11.
4. M. O. Magnasco, "Forced thermal ratchets," Phys. Rev. Lett. 71(10), 1477-1481 (1993). See also L. P. Faucheux, L. S. Bourdieu, P. D. Kaplan, and A. J. Libchaber, "Optical thermal ratchet," ibid. 74(9), 1504-1507 (1995) for a relation of more recent references. For a related system coupled to two thermal baths, see M. M. Millonas, ibid. 74, 10-13 (1995) (errata: ibid. 15, 3027 (1995).
5. M. O. Magnasco, "Forced thermal ratchets," Phys. Rev. Lett. 71(10), 1477-1481 (1993). See also L. P. Faucheux, L. S. Bourdieu, P. D. Kaplan, and A. J. Libchaber, "Optical thermal ratchet," ibid. 74(9), 1504-1507 (1995) for a relation of more recent references. For a related system coupled to two thermal baths, see M. M. Millonas, ibid. 74, 10-13 (1995) (errata: ibid. 15, 3027 (1995).
6. M. O. Magnasco, "Forced thermal ratchets," Phys. Rev. Lett. 71(10), 1477-1481 (1993). See also L. P. Faucheux, L. S. Bourdieu, P. D. Kaplan, and A. J. Libchaber, "Optical thermal ratchet," ibid. 74(9), 1504-1507 (1995) for a relation of more recent references. For a related system coupled to two thermal baths, see M. M. Millonas, ibid. 74, 10-13 (1995) (errata: ibid. 15, 3027 (1995).
7. We follow Feynman's notation where L is not actually the weight but the torque acting on the wheel and θ the angle between two teeth of the ratchet. In any case, the only relevant quantity is the potential energy L θ.
8. B. Andresen, P. Salamon, and R. S. Berry, "Thermodynamics in finite time," Phys. Today 37(9), 62-70 (1984).
9. F. L. Curzon and B. Ahlborn, "Efficiency of a Carnot engine at maximum power output," Am. J. Phys. 43, 22-24 (1975).
10. H. A. Kramers, "Brownian motion in a field of force and the diffusion model of chemical reactions," Physica (Utrecht) 7(4), 284-304 (1940).
11. P. Hänggi, P. Talkner, and M. Borkovec, "Reaction-rate theory: fifty years after Kramers," Rev. Mod. Phys. 62, 251-341 (1990).
12. K. G. Van Kampen, Stochastic Processes in Physics and Chemistry (North-Holland, Amsterdam, 1981), pp. 237-246.
13. 2. We will use Eq. (A6) in order to compute steady state properties only and therefore we can safely neglect this initial condition term.