February 01, 2006

Emergent Spacetime

Nathan Seiberg's review Emergent Spacetime (hep-th 0601234) is most interesting, at least to non-stringy people (with some exceptions, of course). Being at the moment out of town (AdS) near the boundary of the Baltic Sea, and having limited knowledge in these questions I just give some quotes from the conclusions. Seiberg gives no equations, apart from short definitions within the text, so the review is in principle layman readable ;-).

"One challenge is to have emergent spacetime, while preserving some locality - at least macroscopic locality, causality, analyticity, etc. Particularly challenging are the obstacles to formulating physics without time. It is clear that in order to resolve them many of our standard ideas about physics will have to be revolutionized."

"Understanding how time emerges will also have other implications. It will address deep issues like the cosmological singularity and the origin of the Universe."

"With so many different definitions we are tempted to conclude that we should not ask the question: "What is string theory?" Instead, we should ask: "Which string theories have macroscopic dimensions?" Although we do not have an answer to this question, it seems that large N will play an important role in the answer." (Sent as text by wireless webmail.)