Talks by Robert Brandenberger

String Theory and Nonsingular Cosmology

Robert Brandenberger McGill University - Department of Physics

I will argue that in the context of string theory, the Big Bang singularity of standard and inflationary cosmology is automatically resolved. To see this at the level of an effective field theory, ideas from "Double Field Theory" are useful.

Photons and Quantum Gravity in Astrophysics

Asymptotically safe inflation and CMB polarization
The presence of complex critical exponents in the scaling behavior of the Newton constant and Cosmological  constant has dramatic consequences at the inflation scale. In particular an infinite number of unstable de-Sitter vacua emerges from an effective quantum gravitational action. In this framework, the possibility of detecting specific signaturesof a non-gaussian fixed point of the gravitational interactions in the CMB polarization spectrum will then be discussed.

Looking for Cosmic Strings in New Observational Windows

Robert Brandenberger McGill University - Department of Physics
Cosmic strings are predicted to arise in both inflationary and non-inflationary cosmological models. The signatures of such strings will stand out particularly well at higher redshifts. I will discuss how to look for these signatures in CMB redshift and polarization maps and in 21cm redshift surveys.

Meet a Scientist - Prof. Robert Brandenberger

Robert Brandenberger McGill University - Department of Physics
Cosmology as a natural meeting ground for fundamental theory (e.g. superstring theory or quantum gravity) and observations. Exploring how seeds laid down in the very early universe developed into the large scale structure we observe in the universe today.

Holography in String Gas Cosmology

Robert Brandenberger McGill University - Department of Physics
I will review the string gas scenario of structure formation, stressing the role which holography plays. I will also discuss another way of obtaining a scale-invariant spectrum of cosmological perturbations (with specific signatures in the bispectrum) which may be realizable in scenarios based on the AdS/CFT correspondence which can resolve the cosmological singularity.

Cosmology of the Lee-Wick Model

Robert Brandenberger McGill University - Department of Physics
The Lee-Wick model has recently been put forwards as an alternative to supersymmetry for solving the hierarchy problem of particle physics. I will show that, modulo important consistency questions, coupling the Lee-Wick model to cosmology leads to a bouncing universe cosmology with a scale-invariant spectrum of cosmological fluctuations emerging from quantum vacuum fluctuations in the contracting phase.