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Discrete Spacetime and Fluctuating Lambda

28 January 2015

Time: 4:30pm
Venue: See Talk Details
The London Relativity and Cosmology Seminar
Fay Dowker (Imperial)
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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