This series covers all areas of research at Perimeter Institute, as well as those outside of PI's scope.
The solutions to
the cosmological constant problems may involve modifying the very long-range
dynamics of gravity by adding new degrees of freedom. As an example of a conservative and minimal
such modification, we consider the possibility that the graviton has a very
small mass. Massive gravity has received
renewed interest due to recent advances which have resolved its traditional
problems. This kind of modification has
some peculiar and unexpected features, and it points us towards a universe
which looks quite unfamiliar.
A quantum communication channel can be put to many uses: it can transmit
classical information, private classical information, or quantum information.
It can be used alone, with shared entanglement, or together with other
channels. For each of these settings there is a capacity that quantifies a
channel's fundamental potential for communication. In this introductory
talk, I will discuss what we known about the various capacities of a quantum
channel, including a discussion of synergies between different channels and
Some recent searches for quantum gravity signatures using
observations of distant astrophysical sources will be discussed, focusing on
the search for Lorentz invariance violation (LIV) in the form of a dependence
of the photon propagation speed on its energy. Fermi gamma-ray space telescope
observations of ~8 keV to ~30 GeV photons from a short (
burst (GRB 090510) at a cosmological distance (z = 0.903), enabled for the
first time to put a direct time of flight limit on a possible linear variation of
Astronomical hydrodynamics is usually almost ideal in the sense that the Reynolds number (Re) is enormous and any effective viscosity must be due to shocks or turbulence. Astronomical magnetohydrodynamics (MHD) is often also nearly ideal, so that magnetic fields and plasma are well coupled. In particular, dissipation of orbital energy in accretion disks around black holes is readily explained by MHD turbulence. On the other hand, the planet-bearing disks around protostars are magnetically far from ideal because of very low fractional ionization. MHD turbulence is at best marginal
We review recent breakthroughs in understanding
some general features of the Renormalization Group and of Quantum Field Theory.
We discuss some applications of these new results and their deep connection to
the entanglement of the Quantum Field Theory vacuum.
The crucial role that the Higgs boson plays in the
standard model for strong weak and electromagnetic interactions is reviewed.
Recently a resonance with properties consistent with
those expected for the Higgs boson has been discovered at the large hadron collider (LHC).
Conformal field theories have many applications ranging
from continuous phase transitions in Statistical Mechanics to models of beyond
the Standard Model physics in Particle Physics.
In this talk, I will explain another remarkable
application: some conformal field theories can be used to define and study
Quantum Gravity.
I will also try to give a brief summary of some of the
main ideas being discussed at the conference "Back to the Bootstrap II".
There is strong theoretical evidence that black holes have a finite thermodynamic entropy equal to one quarter the area A of the horizon. Providing a microscopic derivation of the entropy of the horizon is a major task for a candidate theory of quantum gravity. Loop quantum gravity has been shown to provide a geometric explanation of the finiteness of the entropy and of the proportionality to the area of the horizon. The microstates are quantum geometries of the horizon.