Abstract
The field of cosmology deals with the properties and evolution of the universe as a whole, and tries to answer questions such as 'What did the universe look like in the past?', 'How did it evolve into its current state?' and 'What will it look like in the future?'.
In this thesis we investigated several formal aspects of cosmological models that are intended to describe the accelerated expansion of the very early universe (also called inflation) and that of the current universe.
Firstly we have examined under which conditions one can avoid particular unwanted instabilities that often appear in models with socalled higher derivatives. Our findings led us to introduce a classification of models that are free of such instabilities.
We have also investigated particular mathematical properties of socalled nonlinear realisations of spacetime symmetries. Such nonlinear realisations occur naturally whenever spacetime symmetries of a model get spontaneously broken. Lastly, based on particular broken spacetime symmetries, we have introduced new inflationary models that can be tested in the near future with the newest generation of satellite experiments.
In this thesis we investigated several formal aspects of cosmological models that are intended to describe the accelerated expansion of the very early universe (also called inflation) and that of the current universe.
Firstly we have examined under which conditions one can avoid particular unwanted instabilities that often appear in models with socalled higher derivatives. Our findings led us to introduce a classification of models that are free of such instabilities.
We have also investigated particular mathematical properties of socalled nonlinear realisations of spacetime symmetries. Such nonlinear realisations occur naturally whenever spacetime symmetries of a model get spontaneously broken. Lastly, based on particular broken spacetime symmetries, we have introduced new inflationary models that can be tested in the near future with the newest generation of satellite experiments.
Original language  English 

Qualification  Doctor of Philosophy 
Awarding Institution 

Supervisors/Advisors 

Award date  13Dec2018 
Place of Publication  [Groningen] 
Publisher  
Print ISBNs  9789403412429 
Electronic ISBNs  9789403412412 
Publication status  Published  2018 