Monday, 30 January 2012

Quantum Darwinism

Darwinism is getting everywhere these days. I had a look at quantum Darwinism recently. My analysis:

In quantum physics, wavefunctions are constantly being copied with variation. Quantum Darwinism essentially proposes that wavefunction collapse represents a form of selection - and that the resulting evolution of the observed universe thus has a Darwinian character.

Quantum Darwinism has been developed mainly by Wojciech Zurek (pictured on the right). It is described in more detail here and here.

Quantum Darwinism appears to be fairly heavily dependent on wavefunction collapse. Wavefunction collapse is a controversial process. So far, no real evidence has been found favouring the idea. It looks like a bunch of made-up nonsense - as was pointed out by Hugh Everett and his Many-worlds interpretation.

Zurek apparently largely rejects many worlds = writing:

There are two key ideas in Everett's writings. The first one is to let quantum theory dictate its own interpretation. We took this "let quantum be quantum" point very seriously. The second message (that often dominates in popular accounts) is the Many Worlds mythology. In contrast "let quantum be quantum" it is less clear what it means, so - in the opinion of this author - there is less reason to take it at face value.
Can quantum Darwinism work without wavefunction collapse? The problem is that there's then no equivalent to death or resource limitation. However, there is still differential reproductive success.

Can one have Darwinism without death? There is still heredity, variation and differential reproductive success. That does tick most of the boxes of Darwinism.

I think it has to be conceded that quantum Darwinism is reasonably accurately named. Whether a Darwinian perspective tells us anything that we didn't already know in this case seems more debatable, though. It may not make a difference to predictions - but it might have an impact on visualisations of the process.

Of course, if the "many-worlds interpretation" ever collapses - so to speak - quantum Darwinism might become a lot more interesting.



  1. Dennett famously said that Natural Selection is the best idea anyone ever had because it integrates us with the rest of the universe as known by science. I believe Quantum Darwinism does the same for quantum theory.

    Zurek describes 'decoherence' rather than wave function collapse.

    There is an 'equivalent to death or resource limitation'. It is that most of the quantum information cannot survive the transfer to its environment during decoherence.

    You might find my paper 'Quantum Darwinism as a Darwinian process' of interest.

    Also my site features the research of Dennett, Dawkins, Blackmore and Zurek (among others):


  2. As you can probably tell from my post, I tend to adopt the MWI perspective - in which case, decoherence doesn't lose anything. Rather it represents worlds splitting. Physical law exhibits microscopic reversibility - so information had better not be getting lost!

    FWIW, I read your abstract while researching this post - and I have visited your "Universal Darwinism" site on many an occasion - hi!