- #1

marcus

Science Advisor

Gold Member

Dearly Missed

- 24,738

- 785

## Main Question or Discussion Point

**Two best QG papers so far this quarter--other ideas?**

Part of doing regular QG NEWS AND OVERVIEW has been having a poll every three months to get people's views on the papers appearing that quarter which they think will be most important for future research----a Most Valuable Paper (MVP) forecast poll.

We are now roughly halfway through the quarter (April-June) and I'm starting to collect nominations---for a short list of candidates for most field-changing paper.

I've seen TWO that in my view are obvious choices so far.

One of them links Triangulation QG with no-extra-dimension String.

The other makes a major advance in discovering braid-matter in QG networks---particles as complications in the state of geometry represented by the evolving LQG network.

**Background on the Triangulations QG paper**

Technical terms are "Causal Dynamical Triangulations" (CDT) and "non-critical String theory".

Non-critical String can include cases where the spacetime dimension is 2, 3 or 4. The CDT people typically get their results by starting off with the easy 2d case and working up to 3d and 4d. They can simulate the appearance and evolution of quantum universes in the computer---approximated using large numbers of 4d triangles called simplexes. Using these simplex building blocks is why it's called "triangulations".

The paper is by 5 people: based in Denmark, Holland, Iceland, Japan and the UK. Their names are Ambjorn, Loll, Westra, Watabiki, and Zohren.

http://arxiv.org/abs/0804.0252

Bear in mind that for them String is a little different from what you might be used to. The string IS the universe. In the 2d case they begin by studying, the universe is spatially a circle, one space dimension. The worldsheet is two-dimensional and it represents spacetime.

**Background on the braid-matter paper**

The braid matter paper is by Song He (Beijing University) and Yidun Wan (Perimeter Institute). http://arxiv.org/abs/0805.0453

I intend to give a light non-technical overview of what is going on with these papers, and also to give, either in this thread or in a separate one, a largescale MAP of QG activities at present. I'd welcome comments of course. If you wish, have a look at the two papers which I'm nominating for this quarter's best-of-lot and contribute some views and explication