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Information - Energy equivalence

  1. Dec 28, 2012 #1
    I was having a discussion with an individual who was claiming that information is a form of energy. I disagreed with that claim. Over the course of the conversation, he provided me with the following article

    http://physicsworld.com/cws/article/news/2010/nov/19/information-converted-to-energy

    The article says that the molecule was placed in an aqueous solution and then electric field was applied to the solution causing the molecule to spin in a given direction, causing it to fall down the potential energy staircase but every once in a while, buffered by the solution (I read buffered as colliding with the molecules in the solution) it rotated in the other direction causing it to go up the staircase. Then the article says that the researched reversed the phase of the field there by preventing it from falling down the potential energy staircase.

    The article then says,
    That statement seems dubious to me. Energy may not have been added from the outside but what about the collisions that test molecule had with the solution it was sitting in? Couldn't it have simply gained that potential from the molecules in the solution? Is it more correct to say that after collisions with the molecules in the solution, the test molecule had more energy than it did before the collision while the molecules in the solution had less energy but the total energy is still the same, just distributed differently. Why say that information was converted to energy?

    Then the article goes on to say,
    That just sounded like bunk to me. Yes the test molecule gained potential but what about the solution it was sitting in? Why isn't that being discussed as part of the system?

    Can someone please shed some light on this for me? The source seems reputable but I'm very skeptical about what they are saying.

    Thanks.
     
  2. jcsd
  3. Dec 28, 2012 #2

    mfb

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    Staff: Mentor

    The energy comes from the liquid, I agree. The interesting result of the experiment is the entropy reduction in the (not closed) system "fluid+particle"*. You could extract the energy stored in the particle, and perform work. This does not reduce the overall entropy, as image processing and the control of the electric field increases entropy more than it gets reduced by the rotation.

    *this leads to the second quote in your post
     
  4. Dec 28, 2012 #3
    I went back and looked at Szilard's engine, the article made a reference to that.
    http://en.wikipedia.org/wiki/Entropy_in_thermodynamics_and_information_theory#Szilard.27s_engine

    if I understand it correctly, his thought experiment was:
    You have 1 atom of gas in a chamber. When that atom is in the bottom half, we put a shutter in and split the chamber in half. Then the piston can drop unopposed in the empty half. When the shutter is opened, work can be performed by the atom.

    I may be way off in my thinking but here's what i got from it.
    When the shutter was closed, the volume available to the atom decreased thus increasing the pressure. This pressure increase is what allows for work to be done.

    What I don't understand is why it says that information was converted to energy.
     
  5. Dec 28, 2012 #4

    mfb

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    Staff: Mentor

    If you know where the particle is, you can use this to operate the engine - you can use this knowledge to convert thermal energy to mechanical energy.
    Information and high-entropy energy (heat) is converted to low-entropy energy.
     
  6. Dec 29, 2012 #5
    I don't fully understand that article. Did they simply create a tiny heat engine? And what do they mean by "converting information to energy"? They can't mean they destroyed information in order to create energy out of nothing. That would violate two fundamental laws of physics. Maybe they mean they moved information from the particle into the surroundings and moved energy from the surroundings into the particle?
     
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