Access

Letters to Nature

Nature 352, 699-701 (22 August 1991) | doi:10.1038/352699a0; Accepted 30 May 1991

Paradoxical behaviour of mechanical and electrical networks

Joel E. Cohen*† & Paul Horowitz‡

  1. †Rockefeller University, 1230 York Avenue, Box 20, New York, New York 10021-6399, USA
  2. ‡Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
  3. *To whom correspondence should be addressed.
Top

WE describe here a network of strings and springs in which cutting a string that supports a weight results in a rise of the weight at equilibrium. In an analogous electronic circuit of passive two-terminal devices (resistors and Zener diodes), adding a current-carrying path increases the voltage drop across the circuit. These systems are mechanical and electrical analogues of a paradox of congested traffic flow1,2. Along with similar hydraulic and thermal analogues, they show how non-intuitive equilibrium behaviour can arise in physical networks made up of classical components.