10 December 2025
Facultad de Ciencias Físicas, UCM
Europe/Madrid timezone

The trans-Planckian problem in cosmology

10 Dec 2025, 12:18
13m
Aula Magna M1 (Facultad de Ciencias Físicas, UCM)

Aula Magna M1

Facultad de Ciencias Físicas, UCM

Plaza de Ciencias 1, 28040 Madrid
Oral presentation Short contributions

Speaker

Christian Durán Romero (Univ. Complutense de Madrid)

Description

This talk presents an overview of the research I am carrying out in my PhD thesis.
Cosmological inflation is the leading framework for describing the physics of the early universe, originally introduced to solve the flatness, horizon, and monopole problems of the standard Big Bang model. It also provides a natural mechanism for generating primordial curvature perturbations: quantum fluctuations of the inflaton field are stretched beyond the Hubble radius during inflation and later re-enter as classical seeds for cosmic structure. The resulting nearly scale-invariant spectrum has been confirmed with high precision by Cosmic Microwave Background observations.

Despite these successes, inflation faces a conceptual challenge when extrapolating observable modes back to the onset of the inflationary era. If inflation lasts significantly longer than the minimal number of e-folds, the comoving modes corresponding to current CMB scales would originate at sub-Planckian wavelengths, where the standard description of spacetime and quantum fields becomes unreliable. This “trans-Planckian problem’’ raises the possibility that unknown ultraviolet physics could imprint corrections on inflationary predictions, potentially modifying the primordial power spectrum.

Author

Christian Durán Romero (Univ. Complutense de Madrid)

Presentation materials