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Quantum physics

Observations turn up the heat

Nature volume 452, pages 705–706 (2008)Cite this article

The idea that observers can influence what they observe has a history that stretches back beyond quantum physics. That we can affect how a system heats up and cools down simply by probing it is a new twist.

As the great quantum physicist Werner Heisenberg — he of the uncertainty principle — made plain, in quantum mechanics, separation of the observer from the phenomenon to be observed is not possible. But in fact, the strange idea that consciousness, intelligence and the act of observation are intertwined with physical phenomena predates Heisenberg. Specifically, James Clerk Maxwell famously introduced into his studies of thermodynamics “a being whose faculties are so sharpened that he can follow every molecule in its course”1, such that it could identify and siphon off the hotter (faster) molecules in a gas2. 'Maxwell's demon' would thus be able to extract useful work from the system, while heat is in effect transferred from a cooler to a hotter region — in clear breach of the normal direction of heat flow from hotter to cooler encapsulated in the second law of thermodynamics.

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Figure 1: Laser quantum heat engines.

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Authors and Affiliations

  1. Kimberly R. Chapin and Marlan O. Scully are at the Institute for Quantum Studies, Texas A&M University, College Station, Texas 77843, USA. k-chapin@tamu.edu,

    Kimberly R. Chapin

  2. Marlan O. Scully is also in the Applied Physics and Materials Science Group, Princeton University, Princeton, New Jersey 08544, USA. scully@tamu.edu,

    Marlan O. Scully

Authors
  1. Kimberly R. Chapin
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  2. Marlan O. Scully
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Chapin, K., Scully, M. Observations turn up the heat. Nature 452, 705–706 (2008). https://doi.org/10.1038/452705a

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