Large Hadron Collider data may falsify supersymmetry

In a recent comment on this blog, Jim Blair said, “I think there is one school of thought in Theoretical Physics where they attempt to use mathematical symmetries to predict the existence of unknown particles.”  I wanted to address this for a moment, because 2011 might be a year in which decades of work in theoretical physics is rendered irrelevant by empirical observation.

Supersymmetry (often abbreviated SUSY) is a heavily-studied physical theory that postulates the existence of “superpartners” of known elementary particles — complementary particles that are heavier and differ by a half-spin.  However, as posted in Nature News, recent data from the Large Hadron Collidor are casting increasing doubt on the correctness of SUSY.  From that article:

“Privately, a lot of people think that the situation is not good for SUSY,” says Alessandro Strumia, a theorist at the University of Pisa in Italy, who recently produced a paper about the impact of the LHC’s latest results on the fine-tuning problem4. “This is a big political issue in our field,” he adds. “For some great physicists, it is the difference between getting a Nobel prize and admitting they spent their lives on the wrong track.” [John] Ellis [of CERN] agrees: “I’ve been working on it for almost 30 years now, and I can imagine that some people might get a little bit nervous.”

Honestly, I think there’s an important lesson here for theoretical computer science and computational complexity theory: don’t base your life’s work on unproven assumptions, divorced from empirical fact.  Otherwise, you risk someone coming along and showing that, hey, we live in Pessiland (or wherever), and all your hard work is confined to a footnote of history.  (Pessiland is a possible cryptographic world that we may live in; Russell Impagliazzo proposed five such possible worlds in 1995.  For more details, including a comment by Boaz Barak about which world experts seem to think we live in, see here.)

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4 responses to “Large Hadron Collider data may falsify supersymmetry

  1. Your point about being empirically grounded is well taken.

  2. On the other hand:

    1. By definition, assumptions are unproven.
    2. Don’t we have to “imagine” something is possible or impossible (a conjecture) in order to organize the search for empirical evidence proving or disproving the conjecture?
    3. Don’t researchers have to make two assumptions about a given conjecture?:
    a. It is resolvable.
    b. Resolving the conjecture is “somehow” useful, relevant or interesting.

    There seems to be a logic for making assumptions, but I am not precisely sure how that logic works.

  3. Check out the new issue of ” Scientific American”.

    Cover story is titled: ” Quantum Gaps in Big Bang Theory; Why our best explanation of how the universe evolved must be fixed – or replaced”.

    If you substitute the term “inflation field” for supersymmetry, the problems are almost identical.

  4. My impression from reading Leonard Susskind’s The Cosmic Landscape is that SUSY is real, just not a feature of our universe because our space is under tension, like a bubble felt from the inside. He equates SUSY with death at the bottom of a phase-transition chain, in fact.

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