# Discrete Spacetime and Fluctuating Lambda

## 28 January 2015

Time: 4:30pmVenue: See Talk Details

Series:

The London Relativity and Cosmology Seminar

Speaker:

Fay Dowker (Imperial)

Abstract:

In the late 1980’s Rafael Sorkin predicted that the Cosmological Term

Lambda(today) should be observed to be, not zero, but of the order of magnitude of (H_0)^2,

which prediction turned out to be in agreement with current observational data. Sorkin used

a heuristic argument from Causal Set Theory — a discrete approach to quantum gravity — to make this

prediction. A more concrete model predicts that Lambda is not constant but fluctuates — even to

negative values — throughout cosmic history so that continuing evidence for constant Lambda

back to larger redshifts would be evidence against this model. I will explain the basics of causal set

quantum gravity and Sorkin’s argument. I will suggest that the current growing tension between high and low

redshift observations may be indicating that Lambda does indeed fluctuate. - Room 516