- #1

marcus

Science Advisor

Gold Member

Dearly Missed

- 24,738

- 785

the last two years have seen a lot of change

there are some new approaches that have either just been discovered (like Smolin's group finding matter degrees of freedom in spin networks)

or have recently become prominent (like asymptotic safety approach of Reuter and Percacci groups)

there are attempts to get different approaches to CONVERGE---like A & G working for the past two years on unifying spin network LQG with Alain Connes Noncommutative Geometry.

and many people including Rovelli and Freidel working on making spinfoam so it has the right low-energy behavior and also matches LQG----if you read the "new spinfoam vertex" papers you see a major focus on unifying spinfoam with canonical LQG.

so there is a trend or a

**groping**towards convergence and unification of approaches.

And Martin Reuter gave a very clear prescription for the next 5 years when they were asked at the end of Loops '07. He wants to see the dimension of the critical hypersurface around the renormalization group fixed point be the same as the number of ambiguities in LQG----some number like three: of parameters that you can nail down and then the theory is predictive. Seriously or not, he gave a vision of equivalence between the two approaches: his and Loop.

In the Q&A at the end of his Asymptotic Safety chapter for Oriti's book, Percacci also described various way the approaches could converge.

Those are some things I see happening or vaguely on the horizon.

**What do you see?**Can you describe in better detail what is going on?

What are some other trends?