School of Physical and Chemical Sciences, Te Kura Matū Seminar Series

Testing cosmological foundations


Professor David Wiltshire


School of Physical and Chemical Sciences, University of Canterbury

Time & Place

Fri, 27 Jul 2018 11:00:00 NZST in West 701

All are welcome


The nature of dark energy is the biggest problem in cosmology. But the answer may not be very different to what most cosmologists assume.

General relativity is not a complete theory. It leaves many important questions unanswered, including the nature of gravitational energy. This is directly relevant to an important observational fact: the Universe is a very inhomogeneous cosmic web on the small scales on which general relativity is actually tested. How one fits one geometry inside another to arrive at an average smooth geometry for the Universe is an open foundational problem. The timescape cosmology is a phenomenological model - without dark energy - which returns to first principles to address such fundamental questions, and to derive observables. It is successful in as far as it can be tested, and it offers falsifiable predictions, which will be tested by future missions such as Euclid. In this talk I will outline the current status of the timescape model, including the most recent observational tests, and how future observations will enable us to nail down key questions in the mystery of what the Universe is made of.


David L Wiltshire is a Professor of Theoretical Physics at the University of Canterbury. He did undergraduate studies at UC followed by a PhD in the Relativity and Gravitation Group at the University of Cambridge, UK, in the mid 1980s. After a variety of research and teaching positions in Italy, UK, and Australia he returned to Christchurch in 2001. He is known for his work in higher-dimensional gravity, brane worlds, black holes and quantum cosmology. Since the mid 2000s his research has turned to the problem of dark energy, the averaging of the inhomogeneous universe in general relativity, and its implications for the foundations of theoretical and observational cosmology. He is on the editorial board of "Classical and Quantum Gravity", an IUPAP representative on the committee of the International Society on General Relativity and Gravitation (ISGRG), President of the New Zealand Institute of Physics, and a member of the Foundational Questions Institute (FQXi). He is also a past President of the Australasian Society for General Relativity and Gravitation.