Discrete Spacetime and Fluctuating Lambda

The London Relativity and Cosmology Seminar
Fay Dowker (Imperial)
January 28th, 2015 at 16:30
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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

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