Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Natural selection acts on the quantum world

  1. Dec 28, 2004 #1


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

  2. jcsd
  3. Dec 28, 2004 #2


    User Avatar
    Science Advisor

    Thanks. Reilly
  4. Dec 29, 2004 #3
    My understanding of QM is mostly intuitive but I don't understand what was proved. It seems intuitively obvious that decoherence will lead to a agreement between observers.
  5. Dec 29, 2004 #4
  6. Dec 29, 2004 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    The issue has been, at least for philosophers who like to dabble in these kinds of things, that QM seems to indicate that the world is not "objective". Via the fact that our observation of a system causes it to be affected, and that there can be a number of different outcomes of an observation, there is a propensity to say that our physical world is subjective and dependent upon who and when it is observed.

    This paper negates that via indicating that there are such things as "pointer states", in which outcomes of an ensemble of states DO give consistent, objective results. It is why experiments can be reproducible! It explains why classical measurements are inherently non-subjective.

    I thought it was an important paper to point out because we often have people asking questions on this issue. I don't expect people to remember this let's say a month from now when one of these things pop up again. But who knows, someone might just be able to counter any more claims about QM or our world be purely "subjective" or "indeterministic" or something along that line.

  7. Jan 5, 2005 #6
    I often think of the world as indeterministic, but not subjective (although sometimes very wierd).

    Our current models of decoherence don't seem to allow us to predict the exact outcomes of individual measurements, and there is the $billion question - what determines the exact outcomes? I don't think anything had been proved at all, back when I was a physics student but I have just been catching up and I am impressed that we actually seem to have made a little progress towards answering the measurement problem....with a long way to go! And I still believe in blind chance.
  8. Jan 9, 2005 #7
    Thanks for the reference. I also viewed another article listed in the margins which had a related theme. "More Ways To Skin Schrodinger's Cat", spoke about the inability of the superimposed states of the photon to collapse in a way that directly affects the cat without involving the surroundings. That is, the photon can not impart it's result directly to the cat in a way that we can be sure the surroundings did not contribute to the final result of the cat 'dead' or 'alive'.

    The articles seemed related because I assumed that the selection process in "Natural Selection Acts on the Quantum World' is only referring to the preference for the stationary state (of say, fundamental particles in nature as well as macrosopic objects). We seem to not yet know the 'code' in nature that forces the stationary state repeatably. For the hydrogen model as an example, a photon is always forced to re-adsorb after the emission, (although it is a different photon). Nature appears to care little about our observation problem after emission and before adsorption, and therefore repeats the process accurately whether we observe it or not. Unlike the Schrodinger's Cat problem neither our knowledge nor observation is changing the result.

    I found it confusing that they would refer to the 'stability' of the preferred states as 'Darwinian'. It seems that they are re-naming something we are very familiar with in physics and the term did not help me understand it further.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Natural selection acts on the quantum world
  1. Quantum world and time (Replies: 1)