Re: cracks and pots

["John Baez" <baez@math.ucr.edu>]

Hi -

> I just came across the following pages
>
> http://motls.blogspot.com/2004/11/category-theory-and-physics.html
> http://motls.blogspot.com/2004/11/this-week-208-analysis.html
>
> written by Lubos Motl, a physicist (string theorist). Some of you may find
> these articles interesting and probably revealing.
>
> Are we category theorists as a whole going to quietly accept getting
> discredited by a minority of us presumably applying category theory to
> string theory?

I can't tell if you're kidding.  I'll assume you're not.

There's nothing wrong with applying category theory to string theory.
The papers by Michael Douglas and Paul Aspinwall cited above by Motl
are some nice examples of using derived categories to study D-branes.

Further examples: the Moore-Seiberg relations turn out to be little
more than the definition of a balanced monoidal category, and the
Segal-Moore axioms for open-closed topological strings are nicely
captured using category theory here:

http://arxiv.org/abs/math.AT/0510664

There were a lot of nice talks on the borderline between category
theory and string theory at the Streetfest.

Perhaps more to the point, Lubos Motl is famous for his heated
rhetoric.  He doesn't like me, or anyone else who criticizes
string theory.  The articles you mention above are mainly reactions
to my This Week's Finds.

He's actually being very gentle - for him.  He even says "the
role of category theory can therefore be described as a `progressive
direction' within string theory".

I'm sure you'll all be pleased to know that.  :-)

> It is surely not too late to react and point out that this is
> not what (all of) category theory is about.

I would urge everyone not to react - at least, not until they are
well aware of what a discussion with him is like.  See his blog
and his comments on Peter Woit's blog if you don't understand what
I mean.   For example:

http://pitofbabel.org/blog/?p=51

> Please give a thought about what
> we, as a community, can urgently do to repair this damaging impression.

Since Motl's personality is well known, any damage will be minimal.
I think we should relax and take it easy.

Best,
jb