## Friday, 31 May 2019

### Uniqueness of the $2d$ critical Ising model

This post is motivated by a request from JHEP to review a recent article by Anton de la Fuente. I am grateful to the author for stimulating correspondence.

#### The conformal bootstrap: analytic vs numerical

The critical Ising model is described by a unitary conformal field theory. In two dimensions, that theory is part of a family called minimal models, which can be exactly solved in the analytic bootstrap framework of Belavin, Polyakov and Zamolodchikov. Minimal models are parametrized by two coprime integers 2 ≤ p < q, they are unitary when q = p + 1, and the Ising model is the case (p, q)=(3, 4).

These 2d bootstrap results date back to the 1980s. More recently, the bootstrap method has been successfully used in higher dimensional CFTs, such as the 3d Ising model. While the basic ideas are the same, there are important technical differences between 2d and higher d.

## Monday, 27 May 2019

### Academics and Wikipedia: the WikiJournal experiment

Since November 2017, I have been an editor of the WikiJournal of Science, a Wikipedia-integrated, broad scope, libre open access journal. For me this is one way of encouraging academics to write in Wikipedia, by making it possible to publish Wikipedia articles in a recognized academic journal. The WikiJournals as they now exist may not yet be ideal for that, but they are already providing valuable insights into the difference between Wikipedia standards and academic standards, academics' attitudes towards Wikipedia, etc.

I am discussing these insights in a Wikipedia essay, for which this blog post is an announcement. This leads me to suggest that WikiJournals be radically reformed - or that any organization with similar aims should follow a different approach. The essay can be discussed at its Talk page.

## Thursday, 9 May 2019

### One software to rule them all? Open source alternatives to Mathematica

This post is based on a joint talk with Riccardo Guida given at IPhT Saclay on May 7th.

Wolfram’s Mathematica has been the dominant computer algebra system for decades (at least in theoretical physics), and in an advertisement it even compared itself to Sauron’s One Ring.

Mathematica’s dominance however does not come from black magic, but rather from its quality and power compared to other available computer algebra systems. But dominant positions are often abused, and Wolfram’s commercial practices can verge on the abusive, though much less systematically than say Elsevier’s. In this blog post we will denounce the problems with Mathematica, and discuss four open source alternatives: SymPy, SageMath, Maxima, and FriCAS. In the case of SymPy, we will also provide a demonstration notebook.