### Speaker

Bianca Dittrich

### Description

I will discuss two versions of the simplicial Lorentizian path integral, namely the (Lorentzian) quantum Regge and the spin foam version. I will do so in the simple context of de Sitter cosmology. This simple example will reveal the important role of light cone irregular configurations in the simplicial path integral — I will show that these can either lead to an exponentially enhanced or an exponentially suppressed amplitude.

I will then highlight an important difference between the spin foams and quantum Regge path integral, which affects the probability for the creation of the (de Sitter) universe.

### External references

- 23100068
- 4771d130-f25d-42c6-903d-0a9e6a9cfcc0
- 60020959-4198-4a00-acb2-ed070784f3f1