Tag Archives: physics

Theoretical Physics Q and A Site

UPDATE: The site has reached 100% commitment, and is about to launch a beta Q&A period.

There is an active proposal at StackExchange to build a research-level Q and A site for theoretical physics. There is a Physics StackExchange site already, for questions at the high school or undergraduate level.  The new site would be expert-level only, like MathOverflow for math, or CSTheory for theoretical computer science.

The new site is currently in the “commitment” phase, meaning more people need to add their names to a list of individuals who want to participate in the site when it does live. If enough people commit (at 79% of requirement as I write this) the site will enter a “private beta” phase, where only those who committed will be able to ask and answer questions for a while.

More information, and the commitment page, is here.


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.)