Conveners
Causal set theory: Friday block 1
- Yasaman Yazdi (Dublin Institute for Advanced Studies)
Causal set theory: Friday block 2
- Yasaman Yazdi (Dublin Institute for Advanced Studies)
Description
If, as many believe will be the case, we are to have a theory of quantum gravity, then one primary question is: what is the structure of a "quantum spacetime"? i.e. what does spacetime look like at microscopic scales near the Planck scale and what would a gravitational path integral yield, in such a theory of quantum gravity? Causal set theory is an approach to quantum gravity that embraces these questions in a nonperturbative and causal manner. In causal set theory the underlying structure of a macroscopic continuum spacetime is proposed to be a fundamentally discrete spacetime with nothing in between the elements and with causal relations between some of the elements. This session will present a status report of causal set theory as well as discuss recent advances in the areas of cosmology, quantum field theory, dynamics and the emergence of spacetime.
I will give an overview of recent work in causal set theory and the status of the field.
We introduce a new approach to measuring proper distances between space-like separated events in Minkowski spacetimes of any dimension. Interestingly, this approach allows us to measure distances up to the Planck scale with arbitrary precision. It also enables us to define reference frames and evaluate some kinematic quantities along time-like paths.
Causal sets are locally finite, partially ordered sets (posets), which are considered as discrete models of spacetime. On the one hand, causal sets corresponding to a spacetime manifold are commonly generated with a random process called sprinkling. This process keeps only a discrete set of points of the manifold and their causal relations (loosing the spacetime symmetries in each...
Causal set theory offers a simple and elegant picture of discrete physics. Unfortunately, though, the vast majority of causal sets do not look anything like continuum spacetimes, and must be excluded if the theory is to describe our actual universe. I will summarize recent results that show that almost all non-manifoldlike causal sets are, in fact, extremely strongly suppressed in the...
One of the best known interactions between quantum field theory and general relativity is the way that horizons gain an associated entropy, given by an area law. Entanglement entropy is a particularly promising candidate as the source of this entropy, and providing an explanation for black hole entropy as entanglement entropy was one of the initial motivations behind the formulation of causal...
Quantum gravity has yet remained elusive from an observational standpoint. In this talk, I will discuss Swerves, a proposal within quantum gravity phenomenology that predicts testable effects in cosmological data. Motivated by considerations in Causal Set Theory, a discrete approach to quantum gravity, we have formulated the covariant Brownian motion of free particles around their geodesics....
We study the statistical fluctuations (such as the variance) of causal set quantities, with particular focus on the causal set action. To facilitate calculating such fluctuations, we develop tools to account for correlations between causal intervals with different cardinalities. We present a convenient decomposition of the fluctuations of the causal set action into contributions that depend on...
