Branches of the Landscape

If you’ve been following the story of the “Landscape” over the past year or so you’d remember that its proponents felt that if it could predict anything it should be able to predict whether or not there will be supersymmetry at low energies. They had great hopes for making this prediction before 2008 when the LHC presumably will tell us whether there is supersymmetry at LHC energies.

Well, tonight one of the biggest proponents of this point of view, Michael Dine, has a new paper out with two co-authors, entitled Branches of the Landscape. In it they conclude:

“From all this, it appears that it is difficult, in principle, to decide whether or not the landscape predicts supersymmetry.”

So, many string theorists now seem to believe that:

1. String theory predicts a landscape of possible vacua.

2. Given the existence of such a landscape, one can’t predict whether or not there will be low-energy supersymmetry (or anything else either).

One wonders it these string theorists ever studied elementary logic and can draw the obvious conclusion from 1. and 2.

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8 Responses to Branches of the Landscape

  1. Peter says:

    Thanks for the information about Lane’s letter to the editor!

  2. DMS says:

    Thought you might be interested in an update to
    “The Thin Line of Theory”.

  3. JC says:

    These landscape papers seem to look more and more silly as time goes on. Has this anthropic trend affected the number of graduate students and/or postdocs entering into string theory over the last two years or so? If I was still a grad student or postdoc, I surely would be very skeptical of any science which attempts to use the anthropic principle.

  4. Anonymous says:

    I wonder if it’s totally out of the question to think of string theory as a branch of mathematics that is very relevant to physics, but is not, in and by itself, physics.

    An example that comes to mind is complex analysis: It is very relevant to physics, and one can give all theorems in the subject a physical interpretation: simple poles are electric charges, branch points are magnetic monopoles, etc. But it is a very simple, two dimensional physics, and although it coincides with certain simplified physical phenomena, it is far from being a complete, and closed description of physical reality.

    The theory of complex function will always be a fundamental and correct ingredient of any mathematical description of the physical world, but it is not the whole story, and one cannot use it to say anything about, let’s say the big bang or the mass of the electron. For that, one needs many more ingredients, and input from experiments.

    My idea is that string theory is a much larger example of the above. It is wonderful, beautiful, very rich, and very coherent, but it is far from being the full story. My point of view is that this is the reason why it cannot make predictions about the physical world, such as the choice of vacuum, for example.

  5. Thomas Larsson says:

    String theorists get together and sign a pact to commit suicide if supersymmetry is not found at the LHC.

    Why wait? Isn’t the anthropic principle intellectual harakiri?

    It is of course true that we live in a universe which is not too hostile to human life. If anything, this must be evidence for Intelligent Design.

  6. Anonymous says:


    The only viable explanation of why university physics departments do string theory is the anthropic principle. We live in that branch of the landscape where string theory is correct and the anthropic principle is valid.

    That string theorists exist at universities is a well-confirmed 6-sigma fact, and string theory predicts string theorists must exist.

    Therefore string theory must be true.

    Elementary logic!

  7. Anonymous says:

    I’ve got an idea for a new version of the anthropic principle:

    String theorists get together and sign a pact to commit suicide if supersymmetry is not found at the LHC.

    Then, in the event it is found, they can claim to have anthropically explained it (if the universe were not supersymmetric, they would all be dead afterall!) and award each other prizes.

  8. D R Lunsford says:

    This is obviously string complementarity.


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