A classic problem in general relativity, long studied by both physicists and philosophers of physics, concerns whether the geodesic principle may be derived from other principles of the theory, or must be posited independently. In a recent paper [Geroch & Weatherall, “The Motion of Small Bodies in Space-Time”, Comm. Math. Phys. (forthcoming)], Bob Geroch and I have introduced...

In this article, we study the implications of string swampland criteria for dark energy in view of ongoing and future cosmological observations. If string theory should be the ultimate quantum gravity theory, there is evidence that exact de Sitter solutions with a positive cosmological constant cannot describe the fate of the late-time universe. Even though cosmological models with dark energy given by a scalar field π evolving...

In this recent Letter [1], we studied the implications of string Swampland conjectures for quintessence models of dark energy. A couple of days ago, a paper appeared [2] which refers to our work but misrepresents what we have done. Here, we set the record straight.

Guth (Phys. Rev. D 23:347–56, 1981) provided a persuasive rationale for inflationary cosmology based on its ability to solve fine-tuning problems of big bang cosmology. Yet one of the most important consequences of inflation was only widely recognized a few years later: inflation provides a mechanism for generating small departures from uniformity, needed to seed formation of subsequent structures, by “freezing out” vacuum fluctuations...

The inflationary scenario is not the only paradigm of early universe cosmology which is consistent with current observations. General criteria will be presented which any successful early universe model must satisfy. Various ways, including inflation, will be presented which satisfy these conditions. It will then be argued that if nature is described at a fundamental level by superstring theory...

Making use of the T-duality symmetry of superstring theory and of the double geometry from double field theory, we argue that cosmological singularities of a homogeneous and isotropic universe disappear. In fact, an apparent big bang singularity in Einstein gravity corresponds to a universe expanding to infinite size in the dual dimensions.

**Publications List **

- Nonsingular ekpyrotic cosmology with a nearly scale-invariant spectrum of cosmological perturbations and gravitational waves – Robert Brandenberger
- Betting on future physics -Mike D. Schneider
- What’s the problem with the cosmological constant? -Mike D. Schneider
- Philosophical Aspects of Cosmology -Chris Smeenk
- Gaining Access to the Early Universe -Chris Smeenk
- T-dual cosmological solutions in double field theory -Robert Brandenberger et al.
- T-dual cosmological solutions in double field theory II -Robert Brandenberger et al.
- A Note on Saari’s Treatment of Rotation Curve Analysis -Kevin Kadowaki
- Geometry and Motion in General Relativity -James Owen Weatherall
- Dark Energy in the Swampland -Robert Brandenberger et al.
- Dark Energy in the Swampland II -Robert Brandenberger et al.
- Inflation and the Origins of Structure -Chris Smeenk
- Beyond Standard Inflationary Cosmology -Robert Brandenberger
- Dual Space-Time and Nonsingular String Cosmology -Robert Brandenberger et al.

**Forthcoming**

Smeenk, C. “Inflation, Dark Matter, and Dark Energy,” (with Malcolm Longair), forthcoming in *Oxford Handbook of the History of Modern Cosmology.*

“Some Philosophical Prehistory of the Earman-Norton Hole Argument,” invited for inclusion in a special issue of *Studies in History and Philosophy of Modern Physics* on the philosophy of Howard Stein, E. Curiel, T. Pashby, and J. Weatherall, eds. Preprint.

Weatherall, J. “On Representational Redundancy, Surplus Structure, and the Hole Argument”, with Clara Bradley. Preprint.

Weatherall, J. “Why Not Categorical Equivalence?” Forthcoming in Hajnal Andreka and Istvan Nemeti on Unity of Science, J. Madarasz and G. Szekeley, eds. Preprint.

Koberinski, A. “Problems with the cosmological constant problem, forthcoming in Philosophy Beyond Spacetime, Oxford University Press. Preprint.”