"What's New In Physics"
John Baez's Stuff
I'm a mathematical physicist. I'm about to make a big career shift: I've been
working on n-categories and fundamental physics, but now I'm going to the
Centre for Quantum Technologies in
Singapore for two years, and I plan to think about technology and the global
ecological crisis. I'll probably keep thinking about the old stuff a bit, too.
When you make fuel from corn, do you use more energy than you gain? Join the
of This Week's Finds features the third part of my interview with Nathan Urban.
Learn how Lake Agassiz flooded out into the Northern Atlantic and made
temperatures in Europe plunge by shutting down the Atlantic Meridional
Overturning Circulation, or AMOC. Could global warming cause a similar event?
Learn about Urban's work on this question. It's a great introduction to the
mathematics of climate modelling!
My students and I got a grant from the Foundational Questions Institute to
categorifying fundamental physics. We've been hard at work:
- Alex Hoffnung,
Christopher Walker and I wrote a
paper that unifies linear algebra and the study of groupoids:
Higher-Dimensional Algebra VII: Groupoidification. This will appear in
Theory and Application of Categories. We are now working on the next two
papers in this series, which will treat Hecke algebras and Hall algebras in
more detail. The first will be called Higher-Dimensional Algebra VIII: the
Hecke Bicategory. This will be based on a paper by Alex Hoffnung called
The Hecke Bicategory.
- Alex Hoffnung,
Chris Rogers and I wrote a paper on
Lie 2-algebras in classical field theory:
Categorified Symplectic Geometry and the Classical String, which will
appear in Communcations in Mathematical Physics. Chris and I then wrote
Categorified Symplectic Geometry and the String Lie 2-Algebra, which will
appear in Homology, Homotopy and Applications.
- Alex Hoffnung and I wrote a paper
on the foundations of differential geometry:
Convenient Categories of Smooth Spaces, which will appear in in
Transactions of the American Mathematical Society.
- John Huerta and I wrote a paper
on the beautiful patterns of particle physics:
The Algebra of Grand Unified Theories, which was published in the
Bulletin of the American Mathematical Society. Then we wrote one
Division Algebras and Supersymmetry I, which will appear in Proceedings
of the NSF/CBMS Conference on Topology, C*-Algebras, and String Theory.
Then we wrote a sequel:
Division Algebras and Supersymmetry II. We wrote an expository article on
the octonions which will appear Scientific American. And we wrote a
Invitation to Higher Gauge Theory, which will appear in General
Relativity and Gravitation.
- Mike Stay and I wrote a
review of category theory and its applications:
Physics, Topology, Logic and Computation: A Rosetta Stone, to appear in
Bob Coecke's volume New Structures for Physics. We also wrote a paper
on Algorithmic thermodynamics.
Here's a great photo of zodiacal light versus the Milky Way, taken in
Tenerife by Daniel Lopez:
What's on This Site
Also try my blog at:
For common questions about physics, you can't beat this:
I don't maintain this Physics FAQ -
Don Koks does, so please
send any comments about it to him, not me!
If reading my stuff makes you want to ask questions, take a look at
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