Seminar series
Date
Mon, 07 Feb 2011
Time
12:00 -
13:00
Location
L3
Speaker
Fay Dowker
Organisation
Imperial College
Abstract: In the continuum the answer to the title question is "no". But if spacetime is
atomic then the answer is yes. And it so happens that there is rather compelling
circumstantial evidence that spacetime is actually discrete at the Planck scale. So now
the question becomes, why if spacetime is discrete should it take the form of a discrete causal
structure or *order*? The answer is that if you don't put causal order in fundamentally
you don't get it out -- at least that's what known models of "emergent
spacetime" indicate. If we want to make life easy for ourselves in quantum gravity, then, we should
plump for discrete causal order (a "causal set") as the inner basis for spacetime. That, however
raises the spectre of wild nonlocality. I will describe recent progress that shows that this
wildness can be tamed. In particular we now have an approximately local action for
causal sets and I'll explain what that means.