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PERIMETER INSTITUTE RECORDED SEMINAR ARCHIVE

Displaying all lectures given by: Jean-Luc Lehners


PIRSA:17110121  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum incompleteness of inflation - part I
Speaker(s): Jean-Luc Lehners
Abstract:
Date: 14/11/2017 - 11:00 am

PIRSA:17060100  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Quantum cosmological instabilities - with and without boundaries
Speaker(s): Jean-Luc Lehners
Abstract: The big bang singularity might be avoided by replacing it with a theory of initial conditions, or by considering a bounce from an earlier contracting phase. I will describe how both proposals can run into difficulties with instabilities when the spacetime must be treated semi-classically (i.e. when ... read more
Date: 27/06/2017 - 10:45 am

PIRSA:16060009  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The Classicality Puzzle
Speaker(s): Jean-Luc Lehners
Abstract: Why was the early universe classical? Along with the big bang singularity problem and the flatness, horizon and inhomogeneity puzzles, this is one of the big unexplained features of the hot big bang scenario. In this talk I will discuss how inflation and ekpyrosis, which have mainly been considered ... read more
Date: 14/06/2016 - 3:20 pm

PIRSA:12100042  ( MP4 Medium Res , MP4 Low Res , MP3 , PDF ) Which Format?
Scalars with Higher Derivatives in Supergravity and Cosmology
Speaker(s): Jean-Luc Lehners
Abstract: There are many situations in cosmology that motivate the study of scalar fields with higher-derivative actions. The best-known such situations are probably k-inflation (with DBI-inflation being a special case) and models based on galileon theories, but even eternal inflation and cyclic universes... read more
Date: 09/10/2012 - 11:00 am

PIRSA:11070028  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Does the Cyclic Universe Avoid the Measure Problem?
Speaker(s): Jean-Luc Lehners
Abstract: In its best understood version, the Steinhardt-Turok cyclic universe contains two crucial ingredients: an unstable field trajectory during the ekpyrotic phase, and the subsequent brane collision corresponding to the crunch/bang transition. These two features act as strong selection principles and de... read more
Date: 13/07/2011 - 12:10 pm

PIRSA:09110140  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Observing the Multifield Cyclic Universe
Speaker(s): Jean-Luc Lehners
Abstract: I will discuss the qualitative differences between the single-field and multifield cyclic universes, in particular the resulting global "phoenix" structure and its relation to dark energy. The multifield cyclic universe arises naturally from embedding the cyclic universe in supergr... read more
Date: 27/11/2009 - 12:00 pm

PIRSA:09100186  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Meet a Scientist - Dr. Jean-Luc Lehners
Speaker(s): Jean-Luc Lehners
Abstract: What, exactly, happened around the time of the Big Bang? Exploring new models inspired by superstring theory and supergravity, e.g. ones in which we live on “branes” that collide with a “big bang”. Satellite experiments to test such models.
Date: 05/10/2009 - 2:40 am
Collection: Meet a Scientist

PIRSA:09070001  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic/Cyclic Cosmology - Lecture 5
Speaker(s): Jean-Luc Lehners
Abstract:
Date: 01/07/2009 - 9:00 am

PIRSA:09060081  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic/Cyclic Cosmology - Lecture 4
Speaker(s): Jean-Luc Lehners
Abstract: TBA
Date: 29/06/2009 - 11:30 am

PIRSA:09060080  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic/Cyclic Cosmology - Lecture 3
Speaker(s): Jean-Luc Lehners
Abstract:
Date: 29/06/2009 - 10:00 am

PIRSA:09060079  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic/Cyclic Cosmology - Lecture 2
Speaker(s): Jean-Luc Lehners
Abstract: TBA
Date: 29/06/2009 - 9:00 am

PIRSA:09060077  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic/Cyclic Cosmology - Lecture 1
Speaker(s): Jean-Luc Lehners
Abstract:
Date: 27/06/2009 - 11:30 am

PIRSA:08030040  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Ekpyrotic Non-Gaussianity
Speaker(s): Jean-Luc Lehners
Abstract:
Date: 06/03/2008 - 4:30 pm
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